v4.19.13 snapshot.
diff --git a/fs/overlayfs/Kconfig b/fs/overlayfs/Kconfig
new file mode 100644
index 0000000..2ef91be
--- /dev/null
+++ b/fs/overlayfs/Kconfig
@@ -0,0 +1,124 @@
+config OVERLAY_FS
+ tristate "Overlay filesystem support"
+ select EXPORTFS
+ help
+ An overlay filesystem combines two filesystems - an 'upper' filesystem
+ and a 'lower' filesystem. When a name exists in both filesystems, the
+ object in the 'upper' filesystem is visible while the object in the
+ 'lower' filesystem is either hidden or, in the case of directories,
+ merged with the 'upper' object.
+
+ For more information see Documentation/filesystems/overlayfs.txt
+
+config OVERLAY_FS_REDIRECT_DIR
+ bool "Overlayfs: turn on redirect directory feature by default"
+ depends on OVERLAY_FS
+ help
+ If this config option is enabled then overlay filesystems will use
+ redirects when renaming directories by default. In this case it is
+ still possible to turn off redirects globally with the
+ "redirect_dir=off" module option or on a filesystem instance basis
+ with the "redirect_dir=off" mount option.
+
+ Note, that redirects are not backward compatible. That is, mounting
+ an overlay which has redirects on a kernel that doesn't support this
+ feature will have unexpected results.
+
+ If unsure, say N.
+
+config OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW
+ bool "Overlayfs: follow redirects even if redirects are turned off"
+ default y
+ depends on OVERLAY_FS
+ help
+ Disable this to get a possibly more secure configuration, but that
+ might not be backward compatible with previous kernels.
+
+ If backward compatibility is not an issue, then it is safe and
+ recommended to say N here.
+
+ For more information, see Documentation/filesystems/overlayfs.txt
+
+ If unsure, say Y.
+
+config OVERLAY_FS_INDEX
+ bool "Overlayfs: turn on inodes index feature by default"
+ depends on OVERLAY_FS
+ help
+ If this config option is enabled then overlay filesystems will use
+ the index directory to map lower inodes to upper inodes by default.
+ In this case it is still possible to turn off index globally with the
+ "index=off" module option or on a filesystem instance basis with the
+ "index=off" mount option.
+
+ The inodes index feature prevents breaking of lower hardlinks on copy
+ up.
+
+ Note, that the inodes index feature is not backward compatible.
+ That is, mounting an overlay which has an inodes index on a kernel
+ that doesn't support this feature will have unexpected results.
+
+ If unsure, say N.
+
+config OVERLAY_FS_NFS_EXPORT
+ bool "Overlayfs: turn on NFS export feature by default"
+ depends on OVERLAY_FS
+ depends on OVERLAY_FS_INDEX
+ depends on !OVERLAY_FS_METACOPY
+ help
+ If this config option is enabled then overlay filesystems will use
+ the index directory to decode overlay NFS file handles by default.
+ In this case, it is still possible to turn off NFS export support
+ globally with the "nfs_export=off" module option or on a filesystem
+ instance basis with the "nfs_export=off" mount option.
+
+ The NFS export feature creates an index on copy up of every file and
+ directory. This full index is used to detect overlay filesystems
+ inconsistencies on lookup, like redirect from multiple upper dirs to
+ the same lower dir. The full index may incur some overhead on mount
+ time, especially when verifying that directory file handles are not
+ stale.
+
+ Note, that the NFS export feature is not backward compatible.
+ That is, mounting an overlay which has a full index on a kernel
+ that doesn't support this feature will have unexpected results.
+
+ Most users should say N here and enable this feature on a case-by-
+ case basis with the "nfs_export=on" mount option.
+
+ Say N unless you fully understand the consequences.
+
+config OVERLAY_FS_XINO_AUTO
+ bool "Overlayfs: auto enable inode number mapping"
+ default n
+ depends on OVERLAY_FS
+ help
+ If this config option is enabled then overlay filesystems will use
+ unused high bits in undelying filesystem inode numbers to map all
+ inodes to a unified address space. The mapped 64bit inode numbers
+ might not be compatible with applications that expect 32bit inodes.
+
+ If compatibility with applications that expect 32bit inodes is not an
+ issue, then it is safe and recommended to say Y here.
+
+ For more information, see Documentation/filesystems/overlayfs.txt
+
+ If unsure, say N.
+
+config OVERLAY_FS_METACOPY
+ bool "Overlayfs: turn on metadata only copy up feature by default"
+ depends on OVERLAY_FS
+ select OVERLAY_FS_REDIRECT_DIR
+ help
+ If this config option is enabled then overlay filesystems will
+ copy up only metadata where appropriate and data copy up will
+ happen when a file is opened for WRITE operation. It is still
+ possible to turn off this feature globally with the "metacopy=off"
+ module option or on a filesystem instance basis with the
+ "metacopy=off" mount option.
+
+ Note, that this feature is not backward compatible. That is,
+ mounting an overlay which has metacopy only inodes on a kernel
+ that doesn't support this feature will have unexpected results.
+
+ If unsure, say N.
diff --git a/fs/overlayfs/Makefile b/fs/overlayfs/Makefile
new file mode 100644
index 0000000..46e1ff8
--- /dev/null
+++ b/fs/overlayfs/Makefile
@@ -0,0 +1,8 @@
+#
+# Makefile for the overlay filesystem.
+#
+
+obj-$(CONFIG_OVERLAY_FS) += overlay.o
+
+overlay-objs := super.o namei.o util.o inode.o file.o dir.o readdir.o \
+ copy_up.o export.o
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
new file mode 100644
index 0000000..1cc797a
--- /dev/null
+++ b/fs/overlayfs/copy_up.c
@@ -0,0 +1,875 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/splice.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/uaccess.h>
+#include <linux/sched/signal.h>
+#include <linux/cred.h>
+#include <linux/namei.h>
+#include <linux/fdtable.h>
+#include <linux/ratelimit.h>
+#include <linux/exportfs.h>
+#include "overlayfs.h"
+
+#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
+
+static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
+{
+ pr_warn("overlayfs: \"check_copy_up\" module option is obsolete\n");
+ return 0;
+}
+
+static int ovl_ccup_get(char *buf, const struct kernel_param *param)
+{
+ return sprintf(buf, "N\n");
+}
+
+module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
+MODULE_PARM_DESC(ovl_check_copy_up, "Obsolete; does nothing");
+
+int ovl_copy_xattr(struct dentry *old, struct dentry *new)
+{
+ ssize_t list_size, size, value_size = 0;
+ char *buf, *name, *value = NULL;
+ int uninitialized_var(error);
+ size_t slen;
+
+ if (!(old->d_inode->i_opflags & IOP_XATTR) ||
+ !(new->d_inode->i_opflags & IOP_XATTR))
+ return 0;
+
+ list_size = vfs_listxattr(old, NULL, 0);
+ if (list_size <= 0) {
+ if (list_size == -EOPNOTSUPP)
+ return 0;
+ return list_size;
+ }
+
+ buf = kzalloc(list_size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ list_size = vfs_listxattr(old, buf, list_size);
+ if (list_size <= 0) {
+ error = list_size;
+ goto out;
+ }
+
+ for (name = buf; list_size; name += slen) {
+ slen = strnlen(name, list_size) + 1;
+
+ /* underlying fs providing us with an broken xattr list? */
+ if (WARN_ON(slen > list_size)) {
+ error = -EIO;
+ break;
+ }
+ list_size -= slen;
+
+ if (ovl_is_private_xattr(name))
+ continue;
+retry:
+ size = vfs_getxattr(old, name, value, value_size);
+ if (size == -ERANGE)
+ size = vfs_getxattr(old, name, NULL, 0);
+
+ if (size < 0) {
+ error = size;
+ break;
+ }
+
+ if (size > value_size) {
+ void *new;
+
+ new = krealloc(value, size, GFP_KERNEL);
+ if (!new) {
+ error = -ENOMEM;
+ break;
+ }
+ value = new;
+ value_size = size;
+ goto retry;
+ }
+
+ error = security_inode_copy_up_xattr(name);
+ if (error < 0 && error != -EOPNOTSUPP)
+ break;
+ if (error == 1) {
+ error = 0;
+ continue; /* Discard */
+ }
+ error = vfs_setxattr(new, name, value, size, 0);
+ if (error)
+ break;
+ }
+ kfree(value);
+out:
+ kfree(buf);
+ return error;
+}
+
+static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
+{
+ struct file *old_file;
+ struct file *new_file;
+ loff_t old_pos = 0;
+ loff_t new_pos = 0;
+ int error = 0;
+
+ if (len == 0)
+ return 0;
+
+ old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
+ if (IS_ERR(old_file))
+ return PTR_ERR(old_file);
+
+ new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
+ if (IS_ERR(new_file)) {
+ error = PTR_ERR(new_file);
+ goto out_fput;
+ }
+
+ /* Try to use clone_file_range to clone up within the same fs */
+ error = do_clone_file_range(old_file, 0, new_file, 0, len);
+ if (!error)
+ goto out;
+ /* Couldn't clone, so now we try to copy the data */
+ error = 0;
+
+ /* FIXME: copy up sparse files efficiently */
+ while (len) {
+ size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
+ long bytes;
+
+ if (len < this_len)
+ this_len = len;
+
+ if (signal_pending_state(TASK_KILLABLE, current)) {
+ error = -EINTR;
+ break;
+ }
+
+ bytes = do_splice_direct(old_file, &old_pos,
+ new_file, &new_pos,
+ this_len, SPLICE_F_MOVE);
+ if (bytes <= 0) {
+ error = bytes;
+ break;
+ }
+ WARN_ON(old_pos != new_pos);
+
+ len -= bytes;
+ }
+out:
+ if (!error)
+ error = vfs_fsync(new_file, 0);
+ fput(new_file);
+out_fput:
+ fput(old_file);
+ return error;
+}
+
+static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
+{
+ struct iattr attr = {
+ .ia_valid = ATTR_SIZE,
+ .ia_size = stat->size,
+ };
+
+ return notify_change(upperdentry, &attr, NULL);
+}
+
+static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
+{
+ struct iattr attr = {
+ .ia_valid =
+ ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
+ .ia_atime = stat->atime,
+ .ia_mtime = stat->mtime,
+ };
+
+ return notify_change(upperdentry, &attr, NULL);
+}
+
+int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
+{
+ int err = 0;
+
+ if (!S_ISLNK(stat->mode)) {
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = stat->mode,
+ };
+ err = notify_change(upperdentry, &attr, NULL);
+ }
+ if (!err) {
+ struct iattr attr = {
+ .ia_valid = ATTR_UID | ATTR_GID,
+ .ia_uid = stat->uid,
+ .ia_gid = stat->gid,
+ };
+ err = notify_change(upperdentry, &attr, NULL);
+ }
+ if (!err)
+ ovl_set_timestamps(upperdentry, stat);
+
+ return err;
+}
+
+struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
+{
+ struct ovl_fh *fh;
+ int fh_type, fh_len, dwords;
+ void *buf;
+ int buflen = MAX_HANDLE_SZ;
+ uuid_t *uuid = &real->d_sb->s_uuid;
+
+ buf = kmalloc(buflen, GFP_KERNEL);
+ if (!buf)
+ return ERR_PTR(-ENOMEM);
+
+ /*
+ * We encode a non-connectable file handle for non-dir, because we
+ * only need to find the lower inode number and we don't want to pay
+ * the price or reconnecting the dentry.
+ */
+ dwords = buflen >> 2;
+ fh_type = exportfs_encode_fh(real, buf, &dwords, 0);
+ buflen = (dwords << 2);
+
+ fh = ERR_PTR(-EIO);
+ if (WARN_ON(fh_type < 0) ||
+ WARN_ON(buflen > MAX_HANDLE_SZ) ||
+ WARN_ON(fh_type == FILEID_INVALID))
+ goto out;
+
+ BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
+ fh_len = offsetof(struct ovl_fh, fid) + buflen;
+ fh = kmalloc(fh_len, GFP_KERNEL);
+ if (!fh) {
+ fh = ERR_PTR(-ENOMEM);
+ goto out;
+ }
+
+ fh->version = OVL_FH_VERSION;
+ fh->magic = OVL_FH_MAGIC;
+ fh->type = fh_type;
+ fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
+ /*
+ * When we will want to decode an overlay dentry from this handle
+ * and all layers are on the same fs, if we get a disconncted real
+ * dentry when we decode fid, the only way to tell if we should assign
+ * it to upperdentry or to lowerstack is by checking this flag.
+ */
+ if (is_upper)
+ fh->flags |= OVL_FH_FLAG_PATH_UPPER;
+ fh->len = fh_len;
+ fh->uuid = *uuid;
+ memcpy(fh->fid, buf, buflen);
+
+out:
+ kfree(buf);
+ return fh;
+}
+
+int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
+ struct dentry *upper)
+{
+ const struct ovl_fh *fh = NULL;
+ int err;
+
+ /*
+ * When lower layer doesn't support export operations store a 'null' fh,
+ * so we can use the overlay.origin xattr to distignuish between a copy
+ * up and a pure upper inode.
+ */
+ if (ovl_can_decode_fh(lower->d_sb)) {
+ fh = ovl_encode_real_fh(lower, false);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+ }
+
+ /*
+ * Do not fail when upper doesn't support xattrs.
+ */
+ err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
+ fh ? fh->len : 0, 0);
+ kfree(fh);
+
+ return err;
+}
+
+/* Store file handle of @upper dir in @index dir entry */
+static int ovl_set_upper_fh(struct dentry *upper, struct dentry *index)
+{
+ const struct ovl_fh *fh;
+ int err;
+
+ fh = ovl_encode_real_fh(upper, true);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
+ err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh, fh->len, 0);
+
+ kfree(fh);
+ return err;
+}
+
+/*
+ * Create and install index entry.
+ *
+ * Caller must hold i_mutex on indexdir.
+ */
+static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
+ struct dentry *upper)
+{
+ struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
+ struct inode *dir = d_inode(indexdir);
+ struct dentry *index = NULL;
+ struct dentry *temp = NULL;
+ struct qstr name = { };
+ int err;
+
+ /*
+ * For now this is only used for creating index entry for directories,
+ * because non-dir are copied up directly to index and then hardlinked
+ * to upper dir.
+ *
+ * TODO: implement create index for non-dir, so we can call it when
+ * encoding file handle for non-dir in case index does not exist.
+ */
+ if (WARN_ON(!d_is_dir(dentry)))
+ return -EIO;
+
+ /* Directory not expected to be indexed before copy up */
+ if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
+ return -EIO;
+
+ err = ovl_get_index_name(origin, &name);
+ if (err)
+ return err;
+
+ temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0));
+ err = PTR_ERR(temp);
+ if (IS_ERR(temp))
+ goto free_name;
+
+ err = ovl_set_upper_fh(upper, temp);
+ if (err)
+ goto out;
+
+ index = lookup_one_len(name.name, indexdir, name.len);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ } else {
+ err = ovl_do_rename(dir, temp, dir, index, 0);
+ dput(index);
+ }
+out:
+ if (err)
+ ovl_cleanup(dir, temp);
+ dput(temp);
+free_name:
+ kfree(name.name);
+ return err;
+}
+
+struct ovl_copy_up_ctx {
+ struct dentry *parent;
+ struct dentry *dentry;
+ struct path lowerpath;
+ struct kstat stat;
+ struct kstat pstat;
+ const char *link;
+ struct dentry *destdir;
+ struct qstr destname;
+ struct dentry *workdir;
+ bool tmpfile;
+ bool origin;
+ bool indexed;
+ bool metacopy;
+};
+
+static int ovl_link_up(struct ovl_copy_up_ctx *c)
+{
+ int err;
+ struct dentry *upper;
+ struct dentry *upperdir = ovl_dentry_upper(c->parent);
+ struct inode *udir = d_inode(upperdir);
+
+ /* Mark parent "impure" because it may now contain non-pure upper */
+ err = ovl_set_impure(c->parent, upperdir);
+ if (err)
+ return err;
+
+ err = ovl_set_nlink_lower(c->dentry);
+ if (err)
+ return err;
+
+ inode_lock_nested(udir, I_MUTEX_PARENT);
+ upper = lookup_one_len(c->dentry->d_name.name, upperdir,
+ c->dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (!IS_ERR(upper)) {
+ err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper);
+ dput(upper);
+
+ if (!err) {
+ /* Restore timestamps on parent (best effort) */
+ ovl_set_timestamps(upperdir, &c->pstat);
+ ovl_dentry_set_upper_alias(c->dentry);
+ }
+ }
+ inode_unlock(udir);
+ if (err)
+ return err;
+
+ err = ovl_set_nlink_upper(c->dentry);
+
+ return err;
+}
+
+static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
+ struct dentry **newdentry)
+{
+ int err;
+ struct dentry *upper;
+ struct inode *udir = d_inode(c->destdir);
+
+ upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
+ if (IS_ERR(upper))
+ return PTR_ERR(upper);
+
+ if (c->tmpfile)
+ err = ovl_do_link(temp, udir, upper);
+ else
+ err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
+
+ if (!err)
+ *newdentry = dget(c->tmpfile ? upper : temp);
+ dput(upper);
+
+ return err;
+}
+
+static struct dentry *ovl_get_tmpfile(struct ovl_copy_up_ctx *c)
+{
+ int err;
+ struct dentry *temp;
+ const struct cred *old_creds = NULL;
+ struct cred *new_creds = NULL;
+ struct ovl_cattr cattr = {
+ /* Can't properly set mode on creation because of the umask */
+ .mode = c->stat.mode & S_IFMT,
+ .rdev = c->stat.rdev,
+ .link = c->link
+ };
+
+ err = security_inode_copy_up(c->dentry, &new_creds);
+ temp = ERR_PTR(err);
+ if (err < 0)
+ goto out;
+
+ if (new_creds)
+ old_creds = override_creds(new_creds);
+
+ if (c->tmpfile)
+ temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
+ else
+ temp = ovl_create_temp(c->workdir, &cattr);
+out:
+ if (new_creds) {
+ revert_creds(old_creds);
+ put_cred(new_creds);
+ }
+
+ return temp;
+}
+
+static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
+{
+ int err;
+
+ err = ovl_copy_xattr(c->lowerpath.dentry, temp);
+ if (err)
+ return err;
+
+ /*
+ * Store identifier of lower inode in upper inode xattr to
+ * allow lookup of the copy up origin inode.
+ *
+ * Don't set origin when we are breaking the association with a lower
+ * hard link.
+ */
+ if (c->origin) {
+ err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
+ if (err)
+ return err;
+ }
+
+ if (S_ISREG(c->stat.mode) && !c->metacopy) {
+ struct path upperpath, datapath;
+
+ ovl_path_upper(c->dentry, &upperpath);
+ BUG_ON(upperpath.dentry != NULL);
+ upperpath.dentry = temp;
+
+ ovl_path_lowerdata(c->dentry, &datapath);
+ err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
+ if (err)
+ return err;
+ }
+
+ if (c->metacopy) {
+ err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
+ NULL, 0, -EOPNOTSUPP);
+ if (err)
+ return err;
+ }
+
+ inode_lock(temp->d_inode);
+ if (c->metacopy)
+ err = ovl_set_size(temp, &c->stat);
+ if (!err)
+ err = ovl_set_attr(temp, &c->stat);
+ inode_unlock(temp->d_inode);
+
+ return err;
+}
+
+static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
+{
+ struct inode *udir = c->destdir->d_inode;
+ struct inode *inode;
+ struct dentry *newdentry = NULL;
+ struct dentry *temp;
+ int err;
+
+ temp = ovl_get_tmpfile(c);
+ if (IS_ERR(temp))
+ return PTR_ERR(temp);
+
+ err = ovl_copy_up_inode(c, temp);
+ if (err)
+ goto out;
+
+ if (S_ISDIR(c->stat.mode) && c->indexed) {
+ err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
+ if (err)
+ goto out;
+ }
+
+ if (c->tmpfile) {
+ inode_lock_nested(udir, I_MUTEX_PARENT);
+ err = ovl_install_temp(c, temp, &newdentry);
+ inode_unlock(udir);
+ } else {
+ err = ovl_install_temp(c, temp, &newdentry);
+ }
+ if (err)
+ goto out;
+
+ if (!c->metacopy)
+ ovl_set_upperdata(d_inode(c->dentry));
+ inode = d_inode(c->dentry);
+ ovl_inode_update(inode, newdentry);
+ if (S_ISDIR(inode->i_mode))
+ ovl_set_flag(OVL_WHITEOUTS, inode);
+
+out:
+ if (err && !c->tmpfile)
+ ovl_cleanup(d_inode(c->workdir), temp);
+ dput(temp);
+ return err;
+
+}
+
+/*
+ * Copy up a single dentry
+ *
+ * All renames start with copy up of source if necessary. The actual
+ * rename will only proceed once the copy up was successful. Copy up uses
+ * upper parent i_mutex for exclusion. Since rename can change d_parent it
+ * is possible that the copy up will lock the old parent. At that point
+ * the file will have already been copied up anyway.
+ */
+static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
+{
+ int err;
+ struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
+ bool to_index = false;
+
+ /*
+ * Indexed non-dir is copied up directly to the index entry and then
+ * hardlinked to upper dir. Indexed dir is copied up to indexdir,
+ * then index entry is created and then copied up dir installed.
+ * Copying dir up to indexdir instead of workdir simplifies locking.
+ */
+ if (ovl_need_index(c->dentry)) {
+ c->indexed = true;
+ if (S_ISDIR(c->stat.mode))
+ c->workdir = ovl_indexdir(c->dentry->d_sb);
+ else
+ to_index = true;
+ }
+
+ if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index)
+ c->origin = true;
+
+ if (to_index) {
+ c->destdir = ovl_indexdir(c->dentry->d_sb);
+ err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);
+ if (err)
+ return err;
+ } else if (WARN_ON(!c->parent)) {
+ /* Disconnected dentry must be copied up to index dir */
+ return -EIO;
+ } else {
+ /*
+ * Mark parent "impure" because it may now contain non-pure
+ * upper
+ */
+ err = ovl_set_impure(c->parent, c->destdir);
+ if (err)
+ return err;
+ }
+
+ /* Should we copyup with O_TMPFILE or with workdir? */
+ if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
+ c->tmpfile = true;
+ err = ovl_copy_up_locked(c);
+ } else {
+ err = ovl_lock_rename_workdir(c->workdir, c->destdir);
+ if (!err) {
+ err = ovl_copy_up_locked(c);
+ unlock_rename(c->workdir, c->destdir);
+ }
+ }
+
+
+ if (err)
+ goto out;
+
+ if (c->indexed)
+ ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
+
+ if (to_index) {
+ /* Initialize nlink for copy up of disconnected dentry */
+ err = ovl_set_nlink_upper(c->dentry);
+ } else {
+ struct inode *udir = d_inode(c->destdir);
+
+ /* Restore timestamps on parent (best effort) */
+ inode_lock(udir);
+ ovl_set_timestamps(c->destdir, &c->pstat);
+ inode_unlock(udir);
+
+ ovl_dentry_set_upper_alias(c->dentry);
+ }
+
+out:
+ if (to_index)
+ kfree(c->destname.name);
+ return err;
+}
+
+static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
+ int flags)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+ if (!ofs->config.metacopy)
+ return false;
+
+ if (!S_ISREG(mode))
+ return false;
+
+ if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
+ return false;
+
+ return true;
+}
+
+/* Copy up data of an inode which was copied up metadata only in the past. */
+static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
+{
+ struct path upperpath, datapath;
+ int err;
+
+ ovl_path_upper(c->dentry, &upperpath);
+ if (WARN_ON(upperpath.dentry == NULL))
+ return -EIO;
+
+ ovl_path_lowerdata(c->dentry, &datapath);
+ if (WARN_ON(datapath.dentry == NULL))
+ return -EIO;
+
+ err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
+ if (err)
+ return err;
+
+ err = vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY);
+ if (err)
+ return err;
+
+ ovl_set_upperdata(d_inode(c->dentry));
+ return err;
+}
+
+static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
+ int flags)
+{
+ int err;
+ DEFINE_DELAYED_CALL(done);
+ struct path parentpath;
+ struct ovl_copy_up_ctx ctx = {
+ .parent = parent,
+ .dentry = dentry,
+ .workdir = ovl_workdir(dentry),
+ };
+
+ if (WARN_ON(!ctx.workdir))
+ return -EROFS;
+
+ ovl_path_lower(dentry, &ctx.lowerpath);
+ err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
+ STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
+ if (err)
+ return err;
+
+ ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
+
+ if (parent) {
+ ovl_path_upper(parent, &parentpath);
+ ctx.destdir = parentpath.dentry;
+ ctx.destname = dentry->d_name;
+
+ err = vfs_getattr(&parentpath, &ctx.pstat,
+ STATX_ATIME | STATX_MTIME,
+ AT_STATX_SYNC_AS_STAT);
+ if (err)
+ return err;
+ }
+
+ /* maybe truncate regular file. this has no effect on dirs */
+ if (flags & O_TRUNC)
+ ctx.stat.size = 0;
+
+ if (S_ISLNK(ctx.stat.mode)) {
+ ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
+ if (IS_ERR(ctx.link))
+ return PTR_ERR(ctx.link);
+ }
+
+ err = ovl_copy_up_start(dentry, flags);
+ /* err < 0: interrupted, err > 0: raced with another copy-up */
+ if (unlikely(err)) {
+ if (err > 0)
+ err = 0;
+ } else {
+ if (!ovl_dentry_upper(dentry))
+ err = ovl_do_copy_up(&ctx);
+ if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
+ err = ovl_link_up(&ctx);
+ if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
+ err = ovl_copy_up_meta_inode_data(&ctx);
+ ovl_copy_up_end(dentry);
+ }
+ do_delayed_call(&done);
+
+ return err;
+}
+
+int ovl_copy_up_flags(struct dentry *dentry, int flags)
+{
+ int err = 0;
+ const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
+ bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
+
+ /*
+ * With NFS export, copy up can get called for a disconnected non-dir.
+ * In this case, we will copy up lower inode to index dir without
+ * linking it to upper dir.
+ */
+ if (WARN_ON(disconnected && d_is_dir(dentry)))
+ return -EIO;
+
+ while (!err) {
+ struct dentry *next;
+ struct dentry *parent = NULL;
+
+ if (ovl_already_copied_up(dentry, flags))
+ break;
+
+ next = dget(dentry);
+ /* find the topmost dentry not yet copied up */
+ for (; !disconnected;) {
+ parent = dget_parent(next);
+
+ if (ovl_dentry_upper(parent))
+ break;
+
+ dput(next);
+ next = parent;
+ }
+
+ err = ovl_copy_up_one(parent, next, flags);
+
+ dput(parent);
+ dput(next);
+ }
+ revert_creds(old_cred);
+
+ return err;
+}
+
+static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
+{
+ /* Copy up of disconnected dentry does not set upper alias */
+ if (ovl_already_copied_up(dentry, flags))
+ return false;
+
+ if (special_file(d_inode(dentry)->i_mode))
+ return false;
+
+ if (!ovl_open_flags_need_copy_up(flags))
+ return false;
+
+ return true;
+}
+
+int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags)
+{
+ int err = 0;
+
+ if (ovl_open_need_copy_up(dentry, file_flags)) {
+ err = ovl_want_write(dentry);
+ if (!err) {
+ err = ovl_copy_up_flags(dentry, file_flags);
+ ovl_drop_write(dentry);
+ }
+ }
+
+ return err;
+}
+
+int ovl_copy_up_with_data(struct dentry *dentry)
+{
+ return ovl_copy_up_flags(dentry, O_WRONLY);
+}
+
+int ovl_copy_up(struct dentry *dentry)
+{
+ return ovl_copy_up_flags(dentry, 0);
+}
diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
new file mode 100644
index 0000000..b2aadd3
--- /dev/null
+++ b/fs/overlayfs/dir.c
@@ -0,0 +1,1254 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include <linux/module.h>
+#include <linux/posix_acl.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/atomic.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+static unsigned short ovl_redirect_max = 256;
+module_param_named(redirect_max, ovl_redirect_max, ushort, 0644);
+MODULE_PARM_DESC(ovl_redirect_max,
+ "Maximum length of absolute redirect xattr value");
+
+static int ovl_set_redirect(struct dentry *dentry, bool samedir);
+
+int ovl_cleanup(struct inode *wdir, struct dentry *wdentry)
+{
+ int err;
+
+ dget(wdentry);
+ if (d_is_dir(wdentry))
+ err = ovl_do_rmdir(wdir, wdentry);
+ else
+ err = ovl_do_unlink(wdir, wdentry);
+ dput(wdentry);
+
+ if (err) {
+ pr_err("overlayfs: cleanup of '%pd2' failed (%i)\n",
+ wdentry, err);
+ }
+
+ return err;
+}
+
+static struct dentry *ovl_lookup_temp(struct dentry *workdir)
+{
+ struct dentry *temp;
+ char name[20];
+ static atomic_t temp_id = ATOMIC_INIT(0);
+
+ /* counter is allowed to wrap, since temp dentries are ephemeral */
+ snprintf(name, sizeof(name), "#%x", atomic_inc_return(&temp_id));
+
+ temp = lookup_one_len(name, workdir, strlen(name));
+ if (!IS_ERR(temp) && temp->d_inode) {
+ pr_err("overlayfs: workdir/%s already exists\n", name);
+ dput(temp);
+ temp = ERR_PTR(-EIO);
+ }
+
+ return temp;
+}
+
+/* caller holds i_mutex on workdir */
+static struct dentry *ovl_whiteout(struct dentry *workdir)
+{
+ int err;
+ struct dentry *whiteout;
+ struct inode *wdir = workdir->d_inode;
+
+ whiteout = ovl_lookup_temp(workdir);
+ if (IS_ERR(whiteout))
+ return whiteout;
+
+ err = ovl_do_whiteout(wdir, whiteout);
+ if (err) {
+ dput(whiteout);
+ whiteout = ERR_PTR(err);
+ }
+
+ return whiteout;
+}
+
+/* Caller must hold i_mutex on both workdir and dir */
+int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
+ struct dentry *dentry)
+{
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *whiteout;
+ int err;
+ int flags = 0;
+
+ whiteout = ovl_whiteout(workdir);
+ err = PTR_ERR(whiteout);
+ if (IS_ERR(whiteout))
+ return err;
+
+ if (d_is_dir(dentry))
+ flags = RENAME_EXCHANGE;
+
+ err = ovl_do_rename(wdir, whiteout, dir, dentry, flags);
+ if (err)
+ goto kill_whiteout;
+ if (flags)
+ ovl_cleanup(wdir, dentry);
+
+out:
+ dput(whiteout);
+ return err;
+
+kill_whiteout:
+ ovl_cleanup(wdir, whiteout);
+ goto out;
+}
+
+static int ovl_mkdir_real(struct inode *dir, struct dentry **newdentry,
+ umode_t mode)
+{
+ int err;
+ struct dentry *d, *dentry = *newdentry;
+
+ err = ovl_do_mkdir(dir, dentry, mode);
+ if (err)
+ return err;
+
+ if (likely(!d_unhashed(dentry)))
+ return 0;
+
+ /*
+ * vfs_mkdir() may succeed and leave the dentry passed
+ * to it unhashed and negative. If that happens, try to
+ * lookup a new hashed and positive dentry.
+ */
+ d = lookup_one_len(dentry->d_name.name, dentry->d_parent,
+ dentry->d_name.len);
+ if (IS_ERR(d)) {
+ pr_warn("overlayfs: failed lookup after mkdir (%pd2, err=%i).\n",
+ dentry, err);
+ return PTR_ERR(d);
+ }
+ dput(dentry);
+ *newdentry = d;
+
+ return 0;
+}
+
+struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
+ struct ovl_cattr *attr)
+{
+ int err;
+
+ if (IS_ERR(newdentry))
+ return newdentry;
+
+ err = -ESTALE;
+ if (newdentry->d_inode)
+ goto out;
+
+ if (attr->hardlink) {
+ err = ovl_do_link(attr->hardlink, dir, newdentry);
+ } else {
+ switch (attr->mode & S_IFMT) {
+ case S_IFREG:
+ err = ovl_do_create(dir, newdentry, attr->mode);
+ break;
+
+ case S_IFDIR:
+ /* mkdir is special... */
+ err = ovl_mkdir_real(dir, &newdentry, attr->mode);
+ break;
+
+ case S_IFCHR:
+ case S_IFBLK:
+ case S_IFIFO:
+ case S_IFSOCK:
+ err = ovl_do_mknod(dir, newdentry, attr->mode,
+ attr->rdev);
+ break;
+
+ case S_IFLNK:
+ err = ovl_do_symlink(dir, newdentry, attr->link);
+ break;
+
+ default:
+ err = -EPERM;
+ }
+ }
+ if (!err && WARN_ON(!newdentry->d_inode)) {
+ /*
+ * Not quite sure if non-instantiated dentry is legal or not.
+ * VFS doesn't seem to care so check and warn here.
+ */
+ err = -EIO;
+ }
+out:
+ if (err) {
+ dput(newdentry);
+ return ERR_PTR(err);
+ }
+ return newdentry;
+}
+
+struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr)
+{
+ return ovl_create_real(d_inode(workdir), ovl_lookup_temp(workdir),
+ attr);
+}
+
+static int ovl_set_opaque_xerr(struct dentry *dentry, struct dentry *upper,
+ int xerr)
+{
+ int err;
+
+ err = ovl_check_setxattr(dentry, upper, OVL_XATTR_OPAQUE, "y", 1, xerr);
+ if (!err)
+ ovl_dentry_set_opaque(dentry);
+
+ return err;
+}
+
+static int ovl_set_opaque(struct dentry *dentry, struct dentry *upperdentry)
+{
+ /*
+ * Fail with -EIO when trying to create opaque dir and upper doesn't
+ * support xattrs. ovl_rename() calls ovl_set_opaque_xerr(-EXDEV) to
+ * return a specific error for noxattr case.
+ */
+ return ovl_set_opaque_xerr(dentry, upperdentry, -EIO);
+}
+
+/*
+ * Common operations required to be done after creation of file on upper.
+ * If @hardlink is false, then @inode is a pre-allocated inode, we may or
+ * may not use to instantiate the new dentry.
+ */
+static int ovl_instantiate(struct dentry *dentry, struct inode *inode,
+ struct dentry *newdentry, bool hardlink)
+{
+ struct ovl_inode_params oip = {
+ .upperdentry = newdentry,
+ .newinode = inode,
+ };
+
+ ovl_dir_modified(dentry->d_parent, false);
+ ovl_dentry_set_upper_alias(dentry);
+ if (!hardlink) {
+ /*
+ * ovl_obtain_alias() can be called after ovl_create_real()
+ * and before we get here, so we may get an inode from cache
+ * with the same real upperdentry that is not the inode we
+ * pre-allocated. In this case we will use the cached inode
+ * to instantiate the new dentry.
+ *
+ * XXX: if we ever use ovl_obtain_alias() to decode directory
+ * file handles, need to use ovl_get_inode_locked() and
+ * d_instantiate_new() here to prevent from creating two
+ * hashed directory inode aliases.
+ */
+ inode = ovl_get_inode(dentry->d_sb, &oip);
+ if (WARN_ON(IS_ERR(inode)))
+ return PTR_ERR(inode);
+ } else {
+ WARN_ON(ovl_inode_real(inode) != d_inode(newdentry));
+ dput(newdentry);
+ inc_nlink(inode);
+ }
+
+ d_instantiate(dentry, inode);
+ if (inode != oip.newinode) {
+ pr_warn_ratelimited("overlayfs: newly created inode found in cache (%pd2)\n",
+ dentry);
+ }
+
+ /* Force lookup of new upper hardlink to find its lower */
+ if (hardlink)
+ d_drop(dentry);
+
+ return 0;
+}
+
+static bool ovl_type_merge(struct dentry *dentry)
+{
+ return OVL_TYPE_MERGE(ovl_path_type(dentry));
+}
+
+static bool ovl_type_origin(struct dentry *dentry)
+{
+ return OVL_TYPE_ORIGIN(ovl_path_type(dentry));
+}
+
+static int ovl_create_upper(struct dentry *dentry, struct inode *inode,
+ struct ovl_cattr *attr)
+{
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *newdentry;
+ int err;
+
+ if (!attr->hardlink && !IS_POSIXACL(udir))
+ attr->mode &= ~current_umask();
+
+ inode_lock_nested(udir, I_MUTEX_PARENT);
+ newdentry = ovl_create_real(udir,
+ lookup_one_len(dentry->d_name.name,
+ upperdir,
+ dentry->d_name.len),
+ attr);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_unlock;
+
+ if (ovl_type_merge(dentry->d_parent) && d_is_dir(newdentry)) {
+ /* Setting opaque here is just an optimization, allow to fail */
+ ovl_set_opaque(dentry, newdentry);
+ }
+
+ err = ovl_instantiate(dentry, inode, newdentry, !!attr->hardlink);
+ if (err)
+ goto out_cleanup;
+out_unlock:
+ inode_unlock(udir);
+ return err;
+
+out_cleanup:
+ ovl_cleanup(udir, newdentry);
+ dput(newdentry);
+ goto out_unlock;
+}
+
+static struct dentry *ovl_clear_empty(struct dentry *dentry,
+ struct list_head *list)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct path upperpath;
+ struct dentry *upper;
+ struct dentry *opaquedir;
+ struct kstat stat;
+ int err;
+
+ if (WARN_ON(!workdir))
+ return ERR_PTR(-EROFS);
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out;
+
+ ovl_path_upper(dentry, &upperpath);
+ err = vfs_getattr(&upperpath, &stat,
+ STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
+ if (err)
+ goto out_unlock;
+
+ err = -ESTALE;
+ if (!S_ISDIR(stat.mode))
+ goto out_unlock;
+ upper = upperpath.dentry;
+ if (upper->d_parent->d_inode != udir)
+ goto out_unlock;
+
+ opaquedir = ovl_create_temp(workdir, OVL_CATTR(stat.mode));
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir))
+ goto out_unlock;
+
+ err = ovl_copy_xattr(upper, opaquedir);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_set_opaque(dentry, opaquedir);
+ if (err)
+ goto out_cleanup;
+
+ inode_lock(opaquedir->d_inode);
+ err = ovl_set_attr(opaquedir, &stat);
+ inode_unlock(opaquedir->d_inode);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_do_rename(wdir, opaquedir, udir, upper, RENAME_EXCHANGE);
+ if (err)
+ goto out_cleanup;
+
+ ovl_cleanup_whiteouts(upper, list);
+ ovl_cleanup(wdir, upper);
+ unlock_rename(workdir, upperdir);
+
+ /* dentry's upper doesn't match now, get rid of it */
+ d_drop(dentry);
+
+ return opaquedir;
+
+out_cleanup:
+ ovl_cleanup(wdir, opaquedir);
+ dput(opaquedir);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out:
+ return ERR_PTR(err);
+}
+
+static int ovl_set_upper_acl(struct dentry *upperdentry, const char *name,
+ const struct posix_acl *acl)
+{
+ void *buffer;
+ size_t size;
+ int err;
+
+ if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !acl)
+ return 0;
+
+ size = posix_acl_to_xattr(NULL, acl, NULL, 0);
+ buffer = kmalloc(size, GFP_KERNEL);
+ if (!buffer)
+ return -ENOMEM;
+
+ size = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
+ err = size;
+ if (err < 0)
+ goto out_free;
+
+ err = vfs_setxattr(upperdentry, name, buffer, size, XATTR_CREATE);
+out_free:
+ kfree(buffer);
+ return err;
+}
+
+static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode,
+ struct ovl_cattr *cattr)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *wdir = workdir->d_inode;
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *udir = upperdir->d_inode;
+ struct dentry *upper;
+ struct dentry *newdentry;
+ int err;
+ struct posix_acl *acl, *default_acl;
+ bool hardlink = !!cattr->hardlink;
+
+ if (WARN_ON(!workdir))
+ return -EROFS;
+
+ if (!hardlink) {
+ err = posix_acl_create(dentry->d_parent->d_inode,
+ &cattr->mode, &default_acl, &acl);
+ if (err)
+ return err;
+ }
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out;
+
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto out_unlock;
+
+ err = -ESTALE;
+ if (d_is_negative(upper) || !IS_WHITEOUT(d_inode(upper)))
+ goto out_dput;
+
+ newdentry = ovl_create_temp(workdir, cattr);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_dput;
+
+ /*
+ * mode could have been mutilated due to umask (e.g. sgid directory)
+ */
+ if (!hardlink &&
+ !S_ISLNK(cattr->mode) &&
+ newdentry->d_inode->i_mode != cattr->mode) {
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = cattr->mode,
+ };
+ inode_lock(newdentry->d_inode);
+ err = notify_change(newdentry, &attr, NULL);
+ inode_unlock(newdentry->d_inode);
+ if (err)
+ goto out_cleanup;
+ }
+ if (!hardlink) {
+ err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_ACCESS,
+ acl);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_set_upper_acl(newdentry, XATTR_NAME_POSIX_ACL_DEFAULT,
+ default_acl);
+ if (err)
+ goto out_cleanup;
+ }
+
+ if (!hardlink && S_ISDIR(cattr->mode)) {
+ err = ovl_set_opaque(dentry, newdentry);
+ if (err)
+ goto out_cleanup;
+
+ err = ovl_do_rename(wdir, newdentry, udir, upper,
+ RENAME_EXCHANGE);
+ if (err)
+ goto out_cleanup;
+
+ ovl_cleanup(wdir, upper);
+ } else {
+ err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
+ if (err)
+ goto out_cleanup;
+ }
+ err = ovl_instantiate(dentry, inode, newdentry, hardlink);
+ if (err)
+ goto out_cleanup;
+out_dput:
+ dput(upper);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out:
+ if (!hardlink) {
+ posix_acl_release(acl);
+ posix_acl_release(default_acl);
+ }
+ return err;
+
+out_cleanup:
+ ovl_cleanup(wdir, newdentry);
+ dput(newdentry);
+ goto out_dput;
+}
+
+static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
+ struct ovl_cattr *attr, bool origin)
+{
+ int err;
+ const struct cred *old_cred;
+ struct cred *override_cred;
+ struct dentry *parent = dentry->d_parent;
+
+ err = ovl_copy_up(parent);
+ if (err)
+ return err;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+
+ /*
+ * When linking a file with copy up origin into a new parent, mark the
+ * new parent dir "impure".
+ */
+ if (origin) {
+ err = ovl_set_impure(parent, ovl_dentry_upper(parent));
+ if (err)
+ goto out_revert_creds;
+ }
+
+ err = -ENOMEM;
+ override_cred = prepare_creds();
+ if (override_cred) {
+ override_cred->fsuid = inode->i_uid;
+ override_cred->fsgid = inode->i_gid;
+ if (!attr->hardlink) {
+ err = security_dentry_create_files_as(dentry,
+ attr->mode, &dentry->d_name, old_cred,
+ override_cred);
+ if (err) {
+ put_cred(override_cred);
+ goto out_revert_creds;
+ }
+ }
+ put_cred(override_creds(override_cred));
+ put_cred(override_cred);
+
+ if (!ovl_dentry_is_whiteout(dentry))
+ err = ovl_create_upper(dentry, inode, attr);
+ else
+ err = ovl_create_over_whiteout(dentry, inode, attr);
+ }
+out_revert_creds:
+ revert_creds(old_cred);
+ return err;
+}
+
+static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
+ const char *link)
+{
+ int err;
+ struct inode *inode;
+ struct ovl_cattr attr = {
+ .rdev = rdev,
+ .link = link,
+ };
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ /* Preallocate inode to be used by ovl_get_inode() */
+ err = -ENOMEM;
+ inode = ovl_new_inode(dentry->d_sb, mode, rdev);
+ if (!inode)
+ goto out_drop_write;
+
+ spin_lock(&inode->i_lock);
+ inode->i_state |= I_CREATING;
+ spin_unlock(&inode->i_lock);
+
+ inode_init_owner(inode, dentry->d_parent->d_inode, mode);
+ attr.mode = inode->i_mode;
+
+ err = ovl_create_or_link(dentry, inode, &attr, false);
+ /* Did we end up using the preallocated inode? */
+ if (inode != d_inode(dentry))
+ iput(inode);
+
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static int ovl_create(struct inode *dir, struct dentry *dentry, umode_t mode,
+ bool excl)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFREG, 0, NULL);
+}
+
+static int ovl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+{
+ return ovl_create_object(dentry, (mode & 07777) | S_IFDIR, 0, NULL);
+}
+
+static int ovl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+ dev_t rdev)
+{
+ /* Don't allow creation of "whiteout" on overlay */
+ if (S_ISCHR(mode) && rdev == WHITEOUT_DEV)
+ return -EPERM;
+
+ return ovl_create_object(dentry, mode, rdev, NULL);
+}
+
+static int ovl_symlink(struct inode *dir, struct dentry *dentry,
+ const char *link)
+{
+ return ovl_create_object(dentry, S_IFLNK, 0, link);
+}
+
+static int ovl_set_link_redirect(struct dentry *dentry)
+{
+ const struct cred *old_cred;
+ int err;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_set_redirect(dentry, false);
+ revert_creds(old_cred);
+
+ return err;
+}
+
+static int ovl_link(struct dentry *old, struct inode *newdir,
+ struct dentry *new)
+{
+ int err;
+ bool locked = false;
+ struct inode *inode;
+
+ err = ovl_want_write(old);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(old);
+ if (err)
+ goto out_drop_write;
+
+ err = ovl_copy_up(new->d_parent);
+ if (err)
+ goto out_drop_write;
+
+ if (ovl_is_metacopy_dentry(old)) {
+ err = ovl_set_link_redirect(old);
+ if (err)
+ goto out_drop_write;
+ }
+
+ err = ovl_nlink_start(old, &locked);
+ if (err)
+ goto out_drop_write;
+
+ inode = d_inode(old);
+ ihold(inode);
+
+ err = ovl_create_or_link(new, inode,
+ &(struct ovl_cattr) {.hardlink = ovl_dentry_upper(old)},
+ ovl_type_origin(old));
+ if (err)
+ iput(inode);
+
+ ovl_nlink_end(old, locked);
+out_drop_write:
+ ovl_drop_write(old);
+out:
+ return err;
+}
+
+static bool ovl_matches_upper(struct dentry *dentry, struct dentry *upper)
+{
+ return d_inode(ovl_dentry_upper(dentry)) == d_inode(upper);
+}
+
+static int ovl_remove_and_whiteout(struct dentry *dentry,
+ struct list_head *list)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct dentry *upper;
+ struct dentry *opaquedir = NULL;
+ int err;
+
+ if (WARN_ON(!workdir))
+ return -EROFS;
+
+ if (!list_empty(list)) {
+ opaquedir = ovl_clear_empty(dentry, list);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir))
+ goto out;
+ }
+
+ err = ovl_lock_rename_workdir(workdir, upperdir);
+ if (err)
+ goto out_dput;
+
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto out_unlock;
+
+ err = -ESTALE;
+ if ((opaquedir && upper != opaquedir) ||
+ (!opaquedir && ovl_dentry_upper(dentry) &&
+ !ovl_matches_upper(dentry, upper))) {
+ goto out_dput_upper;
+ }
+
+ err = ovl_cleanup_and_whiteout(workdir, d_inode(upperdir), upper);
+ if (err)
+ goto out_d_drop;
+
+ ovl_dir_modified(dentry->d_parent, true);
+out_d_drop:
+ d_drop(dentry);
+out_dput_upper:
+ dput(upper);
+out_unlock:
+ unlock_rename(workdir, upperdir);
+out_dput:
+ dput(opaquedir);
+out:
+ return err;
+}
+
+static int ovl_remove_upper(struct dentry *dentry, bool is_dir,
+ struct list_head *list)
+{
+ struct dentry *upperdir = ovl_dentry_upper(dentry->d_parent);
+ struct inode *dir = upperdir->d_inode;
+ struct dentry *upper;
+ struct dentry *opaquedir = NULL;
+ int err;
+
+ if (!list_empty(list)) {
+ opaquedir = ovl_clear_empty(dentry, list);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir))
+ goto out;
+ }
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ upper = lookup_one_len(dentry->d_name.name, upperdir,
+ dentry->d_name.len);
+ err = PTR_ERR(upper);
+ if (IS_ERR(upper))
+ goto out_unlock;
+
+ err = -ESTALE;
+ if ((opaquedir && upper != opaquedir) ||
+ (!opaquedir && !ovl_matches_upper(dentry, upper)))
+ goto out_dput_upper;
+
+ if (is_dir)
+ err = vfs_rmdir(dir, upper);
+ else
+ err = vfs_unlink(dir, upper, NULL);
+ ovl_dir_modified(dentry->d_parent, ovl_type_origin(dentry));
+
+ /*
+ * Keeping this dentry hashed would mean having to release
+ * upperpath/lowerpath, which could only be done if we are the
+ * sole user of this dentry. Too tricky... Just unhash for
+ * now.
+ */
+ if (!err)
+ d_drop(dentry);
+out_dput_upper:
+ dput(upper);
+out_unlock:
+ inode_unlock(dir);
+ dput(opaquedir);
+out:
+ return err;
+}
+
+static bool ovl_pure_upper(struct dentry *dentry)
+{
+ return !ovl_dentry_lower(dentry) &&
+ !ovl_test_flag(OVL_WHITEOUTS, d_inode(dentry));
+}
+
+static int ovl_do_remove(struct dentry *dentry, bool is_dir)
+{
+ int err;
+ bool locked = false;
+ const struct cred *old_cred;
+ struct dentry *upperdentry;
+ bool lower_positive = ovl_lower_positive(dentry);
+ LIST_HEAD(list);
+
+ /* No need to clean pure upper removed by vfs_rmdir() */
+ if (is_dir && (lower_positive || !ovl_pure_upper(dentry))) {
+ err = ovl_check_empty_dir(dentry, &list);
+ if (err)
+ goto out;
+ }
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(dentry->d_parent);
+ if (err)
+ goto out_drop_write;
+
+ err = ovl_nlink_start(dentry, &locked);
+ if (err)
+ goto out_drop_write;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ if (!lower_positive)
+ err = ovl_remove_upper(dentry, is_dir, &list);
+ else
+ err = ovl_remove_and_whiteout(dentry, &list);
+ revert_creds(old_cred);
+ if (!err) {
+ if (is_dir)
+ clear_nlink(dentry->d_inode);
+ else
+ drop_nlink(dentry->d_inode);
+ }
+ ovl_nlink_end(dentry, locked);
+
+ /*
+ * Copy ctime
+ *
+ * Note: we fail to update ctime if there was no copy-up, only a
+ * whiteout
+ */
+ upperdentry = ovl_dentry_upper(dentry);
+ if (upperdentry)
+ ovl_copyattr(d_inode(upperdentry), d_inode(dentry));
+
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ ovl_cache_free(&list);
+ return err;
+}
+
+static int ovl_unlink(struct inode *dir, struct dentry *dentry)
+{
+ return ovl_do_remove(dentry, false);
+}
+
+static int ovl_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ return ovl_do_remove(dentry, true);
+}
+
+static bool ovl_type_merge_or_lower(struct dentry *dentry)
+{
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ return OVL_TYPE_MERGE(type) || !OVL_TYPE_UPPER(type);
+}
+
+static bool ovl_can_move(struct dentry *dentry)
+{
+ return ovl_redirect_dir(dentry->d_sb) ||
+ !d_is_dir(dentry) || !ovl_type_merge_or_lower(dentry);
+}
+
+static char *ovl_get_redirect(struct dentry *dentry, bool abs_redirect)
+{
+ char *buf, *ret;
+ struct dentry *d, *tmp;
+ int buflen = ovl_redirect_max + 1;
+
+ if (!abs_redirect) {
+ ret = kstrndup(dentry->d_name.name, dentry->d_name.len,
+ GFP_KERNEL);
+ goto out;
+ }
+
+ buf = ret = kmalloc(buflen, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ buflen--;
+ buf[buflen] = '\0';
+ for (d = dget(dentry); !IS_ROOT(d);) {
+ const char *name;
+ int thislen;
+
+ spin_lock(&d->d_lock);
+ name = ovl_dentry_get_redirect(d);
+ if (name) {
+ thislen = strlen(name);
+ } else {
+ name = d->d_name.name;
+ thislen = d->d_name.len;
+ }
+
+ /* If path is too long, fall back to userspace move */
+ if (thislen + (name[0] != '/') > buflen) {
+ ret = ERR_PTR(-EXDEV);
+ spin_unlock(&d->d_lock);
+ goto out_put;
+ }
+
+ buflen -= thislen;
+ memcpy(&buf[buflen], name, thislen);
+ tmp = dget_dlock(d->d_parent);
+ spin_unlock(&d->d_lock);
+
+ dput(d);
+ d = tmp;
+
+ /* Absolute redirect: finished */
+ if (buf[buflen] == '/')
+ break;
+ buflen--;
+ buf[buflen] = '/';
+ }
+ ret = kstrdup(&buf[buflen], GFP_KERNEL);
+out_put:
+ dput(d);
+ kfree(buf);
+out:
+ return ret ? ret : ERR_PTR(-ENOMEM);
+}
+
+static bool ovl_need_absolute_redirect(struct dentry *dentry, bool samedir)
+{
+ struct dentry *lowerdentry;
+
+ if (!samedir)
+ return true;
+
+ if (d_is_dir(dentry))
+ return false;
+
+ /*
+ * For non-dir hardlinked files, we need absolute redirects
+ * in general as two upper hardlinks could be in different
+ * dirs. We could put a relative redirect now and convert
+ * it to absolute redirect later. But when nlink > 1 and
+ * indexing is on, that means relative redirect needs to be
+ * converted to absolute during copy up of another lower
+ * hardllink as well.
+ *
+ * So without optimizing too much, just check if lower is
+ * a hard link or not. If lower is hard link, put absolute
+ * redirect.
+ */
+ lowerdentry = ovl_dentry_lower(dentry);
+ return (d_inode(lowerdentry)->i_nlink > 1);
+}
+
+static int ovl_set_redirect(struct dentry *dentry, bool samedir)
+{
+ int err;
+ const char *redirect = ovl_dentry_get_redirect(dentry);
+ bool absolute_redirect = ovl_need_absolute_redirect(dentry, samedir);
+
+ if (redirect && (!absolute_redirect || redirect[0] == '/'))
+ return 0;
+
+ redirect = ovl_get_redirect(dentry, absolute_redirect);
+ if (IS_ERR(redirect))
+ return PTR_ERR(redirect);
+
+ err = ovl_check_setxattr(dentry, ovl_dentry_upper(dentry),
+ OVL_XATTR_REDIRECT,
+ redirect, strlen(redirect), -EXDEV);
+ if (!err) {
+ spin_lock(&dentry->d_lock);
+ ovl_dentry_set_redirect(dentry, redirect);
+ spin_unlock(&dentry->d_lock);
+ } else {
+ kfree(redirect);
+ pr_warn_ratelimited("overlayfs: failed to set redirect (%i)\n",
+ err);
+ /* Fall back to userspace copy-up */
+ err = -EXDEV;
+ }
+ return err;
+}
+
+static int ovl_rename(struct inode *olddir, struct dentry *old,
+ struct inode *newdir, struct dentry *new,
+ unsigned int flags)
+{
+ int err;
+ bool locked = false;
+ struct dentry *old_upperdir;
+ struct dentry *new_upperdir;
+ struct dentry *olddentry;
+ struct dentry *newdentry;
+ struct dentry *trap;
+ bool old_opaque;
+ bool new_opaque;
+ bool cleanup_whiteout = false;
+ bool overwrite = !(flags & RENAME_EXCHANGE);
+ bool is_dir = d_is_dir(old);
+ bool new_is_dir = d_is_dir(new);
+ bool samedir = olddir == newdir;
+ struct dentry *opaquedir = NULL;
+ const struct cred *old_cred = NULL;
+ LIST_HEAD(list);
+
+ err = -EINVAL;
+ if (flags & ~(RENAME_EXCHANGE | RENAME_NOREPLACE))
+ goto out;
+
+ flags &= ~RENAME_NOREPLACE;
+
+ /* Don't copy up directory trees */
+ err = -EXDEV;
+ if (!ovl_can_move(old))
+ goto out;
+ if (!overwrite && !ovl_can_move(new))
+ goto out;
+
+ if (overwrite && new_is_dir && !ovl_pure_upper(new)) {
+ err = ovl_check_empty_dir(new, &list);
+ if (err)
+ goto out;
+ }
+
+ if (overwrite) {
+ if (ovl_lower_positive(old)) {
+ if (!ovl_dentry_is_whiteout(new)) {
+ /* Whiteout source */
+ flags |= RENAME_WHITEOUT;
+ } else {
+ /* Switch whiteouts */
+ flags |= RENAME_EXCHANGE;
+ }
+ } else if (is_dir && ovl_dentry_is_whiteout(new)) {
+ flags |= RENAME_EXCHANGE;
+ cleanup_whiteout = true;
+ }
+ }
+
+ err = ovl_want_write(old);
+ if (err)
+ goto out;
+
+ err = ovl_copy_up(old);
+ if (err)
+ goto out_drop_write;
+
+ err = ovl_copy_up(new->d_parent);
+ if (err)
+ goto out_drop_write;
+ if (!overwrite) {
+ err = ovl_copy_up(new);
+ if (err)
+ goto out_drop_write;
+ } else {
+ err = ovl_nlink_start(new, &locked);
+ if (err)
+ goto out_drop_write;
+ }
+
+ old_cred = ovl_override_creds(old->d_sb);
+
+ if (!list_empty(&list)) {
+ opaquedir = ovl_clear_empty(new, &list);
+ err = PTR_ERR(opaquedir);
+ if (IS_ERR(opaquedir)) {
+ opaquedir = NULL;
+ goto out_revert_creds;
+ }
+ }
+
+ old_upperdir = ovl_dentry_upper(old->d_parent);
+ new_upperdir = ovl_dentry_upper(new->d_parent);
+
+ if (!samedir) {
+ /*
+ * When moving a merge dir or non-dir with copy up origin into
+ * a new parent, we are marking the new parent dir "impure".
+ * When ovl_iterate() iterates an "impure" upper dir, it will
+ * lookup the origin inodes of the entries to fill d_ino.
+ */
+ if (ovl_type_origin(old)) {
+ err = ovl_set_impure(new->d_parent, new_upperdir);
+ if (err)
+ goto out_revert_creds;
+ }
+ if (!overwrite && ovl_type_origin(new)) {
+ err = ovl_set_impure(old->d_parent, old_upperdir);
+ if (err)
+ goto out_revert_creds;
+ }
+ }
+
+ trap = lock_rename(new_upperdir, old_upperdir);
+
+ olddentry = lookup_one_len(old->d_name.name, old_upperdir,
+ old->d_name.len);
+ err = PTR_ERR(olddentry);
+ if (IS_ERR(olddentry))
+ goto out_unlock;
+
+ err = -ESTALE;
+ if (!ovl_matches_upper(old, olddentry))
+ goto out_dput_old;
+
+ newdentry = lookup_one_len(new->d_name.name, new_upperdir,
+ new->d_name.len);
+ err = PTR_ERR(newdentry);
+ if (IS_ERR(newdentry))
+ goto out_dput_old;
+
+ old_opaque = ovl_dentry_is_opaque(old);
+ new_opaque = ovl_dentry_is_opaque(new);
+
+ err = -ESTALE;
+ if (d_inode(new) && ovl_dentry_upper(new)) {
+ if (opaquedir) {
+ if (newdentry != opaquedir)
+ goto out_dput;
+ } else {
+ if (!ovl_matches_upper(new, newdentry))
+ goto out_dput;
+ }
+ } else {
+ if (!d_is_negative(newdentry) &&
+ (!new_opaque || !ovl_is_whiteout(newdentry)))
+ goto out_dput;
+ }
+
+ if (olddentry == trap)
+ goto out_dput;
+ if (newdentry == trap)
+ goto out_dput;
+
+ if (WARN_ON(olddentry->d_inode == newdentry->d_inode))
+ goto out_dput;
+
+ err = 0;
+ if (ovl_type_merge_or_lower(old))
+ err = ovl_set_redirect(old, samedir);
+ else if (is_dir && !old_opaque && ovl_type_merge(new->d_parent))
+ err = ovl_set_opaque_xerr(old, olddentry, -EXDEV);
+ if (err)
+ goto out_dput;
+
+ if (!overwrite && ovl_type_merge_or_lower(new))
+ err = ovl_set_redirect(new, samedir);
+ else if (!overwrite && new_is_dir && !new_opaque &&
+ ovl_type_merge(old->d_parent))
+ err = ovl_set_opaque_xerr(new, newdentry, -EXDEV);
+ if (err)
+ goto out_dput;
+
+ err = ovl_do_rename(old_upperdir->d_inode, olddentry,
+ new_upperdir->d_inode, newdentry, flags);
+ if (err)
+ goto out_dput;
+
+ if (cleanup_whiteout)
+ ovl_cleanup(old_upperdir->d_inode, newdentry);
+
+ if (overwrite && d_inode(new)) {
+ if (new_is_dir)
+ clear_nlink(d_inode(new));
+ else
+ drop_nlink(d_inode(new));
+ }
+
+ ovl_dir_modified(old->d_parent, ovl_type_origin(old) ||
+ (!overwrite && ovl_type_origin(new)));
+ ovl_dir_modified(new->d_parent, ovl_type_origin(old) ||
+ (d_inode(new) && ovl_type_origin(new)));
+
+ /* copy ctime: */
+ ovl_copyattr(d_inode(olddentry), d_inode(old));
+ if (d_inode(new) && ovl_dentry_upper(new))
+ ovl_copyattr(d_inode(newdentry), d_inode(new));
+
+out_dput:
+ dput(newdentry);
+out_dput_old:
+ dput(olddentry);
+out_unlock:
+ unlock_rename(new_upperdir, old_upperdir);
+out_revert_creds:
+ revert_creds(old_cred);
+ ovl_nlink_end(new, locked);
+out_drop_write:
+ ovl_drop_write(old);
+out:
+ dput(opaquedir);
+ ovl_cache_free(&list);
+ return err;
+}
+
+const struct inode_operations ovl_dir_inode_operations = {
+ .lookup = ovl_lookup,
+ .mkdir = ovl_mkdir,
+ .symlink = ovl_symlink,
+ .unlink = ovl_unlink,
+ .rmdir = ovl_rmdir,
+ .rename = ovl_rename,
+ .link = ovl_link,
+ .setattr = ovl_setattr,
+ .create = ovl_create,
+ .mknod = ovl_mknod,
+ .permission = ovl_permission,
+ .getattr = ovl_getattr,
+ .listxattr = ovl_listxattr,
+ .get_acl = ovl_get_acl,
+ .update_time = ovl_update_time,
+};
diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
new file mode 100644
index 0000000..54e5d17
--- /dev/null
+++ b/fs/overlayfs/export.c
@@ -0,0 +1,851 @@
+/*
+ * Overlayfs NFS export support.
+ *
+ * Amir Goldstein <amir73il@gmail.com>
+ *
+ * Copyright (C) 2017-2018 CTERA Networks. All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/cred.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/exportfs.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+static int ovl_encode_maybe_copy_up(struct dentry *dentry)
+{
+ int err;
+
+ if (ovl_dentry_upper(dentry))
+ return 0;
+
+ err = ovl_want_write(dentry);
+ if (!err) {
+ err = ovl_copy_up(dentry);
+ ovl_drop_write(dentry);
+ }
+
+ if (err) {
+ pr_warn_ratelimited("overlayfs: failed to copy up on encode (%pd2, err=%i)\n",
+ dentry, err);
+ }
+
+ return err;
+}
+
+/*
+ * Before encoding a non-upper directory file handle from real layer N, we need
+ * to check if it will be possible to reconnect an overlay dentry from the real
+ * lower decoded dentry. This is done by following the overlay ancestry up to a
+ * "layer N connected" ancestor and verifying that all parents along the way are
+ * "layer N connectable". If an ancestor that is NOT "layer N connectable" is
+ * found, we need to copy up an ancestor, which is "layer N connectable", thus
+ * making that ancestor "layer N connected". For example:
+ *
+ * layer 1: /a
+ * layer 2: /a/b/c
+ *
+ * The overlay dentry /a is NOT "layer 2 connectable", because if dir /a is
+ * copied up and renamed, upper dir /a will be indexed by lower dir /a from
+ * layer 1. The dir /a from layer 2 will never be indexed, so the algorithm (*)
+ * in ovl_lookup_real_ancestor() will not be able to lookup a connected overlay
+ * dentry from the connected lower dentry /a/b/c.
+ *
+ * To avoid this problem on decode time, we need to copy up an ancestor of
+ * /a/b/c, which is "layer 2 connectable", on encode time. That ancestor is
+ * /a/b. After copy up (and index) of /a/b, it will become "layer 2 connected"
+ * and when the time comes to decode the file handle from lower dentry /a/b/c,
+ * ovl_lookup_real_ancestor() will find the indexed ancestor /a/b and decoding
+ * a connected overlay dentry will be accomplished.
+ *
+ * (*) the algorithm in ovl_lookup_real_ancestor() can be improved to lookup an
+ * entry /a in the lower layers above layer N and find the indexed dir /a from
+ * layer 1. If that improvement is made, then the check for "layer N connected"
+ * will need to verify there are no redirects in lower layers above N. In the
+ * example above, /a will be "layer 2 connectable". However, if layer 2 dir /a
+ * is a target of a layer 1 redirect, then /a will NOT be "layer 2 connectable":
+ *
+ * layer 1: /A (redirect = /a)
+ * layer 2: /a/b/c
+ */
+
+/* Return the lowest layer for encoding a connectable file handle */
+static int ovl_connectable_layer(struct dentry *dentry)
+{
+ struct ovl_entry *oe = OVL_E(dentry);
+
+ /* We can get overlay root from root of any layer */
+ if (dentry == dentry->d_sb->s_root)
+ return oe->numlower;
+
+ /*
+ * If it's an unindexed merge dir, then it's not connectable with any
+ * lower layer
+ */
+ if (ovl_dentry_upper(dentry) &&
+ !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+ return 0;
+
+ /* We can get upper/overlay path from indexed/lower dentry */
+ return oe->lowerstack[0].layer->idx;
+}
+
+/*
+ * @dentry is "connected" if all ancestors up to root or a "connected" ancestor
+ * have the same uppermost lower layer as the origin's layer. We may need to
+ * copy up a "connectable" ancestor to make it "connected". A "connected" dentry
+ * cannot become non "connected", so cache positive result in dentry flags.
+ *
+ * Return the connected origin layer or < 0 on error.
+ */
+static int ovl_connect_layer(struct dentry *dentry)
+{
+ struct dentry *next, *parent = NULL;
+ int origin_layer;
+ int err = 0;
+
+ if (WARN_ON(dentry == dentry->d_sb->s_root) ||
+ WARN_ON(!ovl_dentry_lower(dentry)))
+ return -EIO;
+
+ origin_layer = OVL_E(dentry)->lowerstack[0].layer->idx;
+ if (ovl_dentry_test_flag(OVL_E_CONNECTED, dentry))
+ return origin_layer;
+
+ /* Find the topmost origin layer connectable ancestor of @dentry */
+ next = dget(dentry);
+ for (;;) {
+ parent = dget_parent(next);
+ if (WARN_ON(parent == next)) {
+ err = -EIO;
+ break;
+ }
+
+ /*
+ * If @parent is not origin layer connectable, then copy up
+ * @next which is origin layer connectable and we are done.
+ */
+ if (ovl_connectable_layer(parent) < origin_layer) {
+ err = ovl_encode_maybe_copy_up(next);
+ break;
+ }
+
+ /* If @parent is connected or indexed we are done */
+ if (ovl_dentry_test_flag(OVL_E_CONNECTED, parent) ||
+ ovl_test_flag(OVL_INDEX, d_inode(parent)))
+ break;
+
+ dput(next);
+ next = parent;
+ }
+
+ dput(parent);
+ dput(next);
+
+ if (!err)
+ ovl_dentry_set_flag(OVL_E_CONNECTED, dentry);
+
+ return err ?: origin_layer;
+}
+
+/*
+ * We only need to encode origin if there is a chance that the same object was
+ * encoded pre copy up and then we need to stay consistent with the same
+ * encoding also after copy up. If non-pure upper is not indexed, then it was
+ * copied up before NFS export was enabled. In that case we don't need to worry
+ * about staying consistent with pre copy up encoding and we encode an upper
+ * file handle. Overlay root dentry is a private case of non-indexed upper.
+ *
+ * The following table summarizes the different file handle encodings used for
+ * different overlay object types:
+ *
+ * Object type | Encoding
+ * --------------------------------
+ * Pure upper | U
+ * Non-indexed upper | U
+ * Indexed upper | L (*)
+ * Non-upper | L (*)
+ *
+ * U = upper file handle
+ * L = lower file handle
+ *
+ * (*) Connecting an overlay dir from real lower dentry is not always
+ * possible when there are redirects in lower layers and non-indexed merge dirs.
+ * To mitigate those case, we may copy up the lower dir ancestor before encode
+ * a lower dir file handle.
+ *
+ * Return 0 for upper file handle, > 0 for lower file handle or < 0 on error.
+ */
+static int ovl_check_encode_origin(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+ /* Upper file handle for pure upper */
+ if (!ovl_dentry_lower(dentry))
+ return 0;
+
+ /*
+ * Upper file handle for non-indexed upper.
+ *
+ * Root is never indexed, so if there's an upper layer, encode upper for
+ * root.
+ */
+ if (ovl_dentry_upper(dentry) &&
+ !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+ return 0;
+
+ /*
+ * Decoding a merge dir, whose origin's ancestor is under a redirected
+ * lower dir or under a non-indexed upper is not always possible.
+ * ovl_connect_layer() will try to make origin's layer "connected" by
+ * copying up a "connectable" ancestor.
+ */
+ if (d_is_dir(dentry) && ofs->upper_mnt)
+ return ovl_connect_layer(dentry);
+
+ /* Lower file handle for indexed and non-upper dir/non-dir */
+ return 1;
+}
+
+static int ovl_d_to_fh(struct dentry *dentry, char *buf, int buflen)
+{
+ struct ovl_fh *fh = NULL;
+ int err, enc_lower;
+
+ /*
+ * Check if we should encode a lower or upper file handle and maybe
+ * copy up an ancestor to make lower file handle connectable.
+ */
+ err = enc_lower = ovl_check_encode_origin(dentry);
+ if (enc_lower < 0)
+ goto fail;
+
+ /* Encode an upper or lower file handle */
+ fh = ovl_encode_real_fh(enc_lower ? ovl_dentry_lower(dentry) :
+ ovl_dentry_upper(dentry), !enc_lower);
+ err = PTR_ERR(fh);
+ if (IS_ERR(fh))
+ goto fail;
+
+ err = -EOVERFLOW;
+ if (fh->len > buflen)
+ goto fail;
+
+ memcpy(buf, (char *)fh, fh->len);
+ err = fh->len;
+
+out:
+ kfree(fh);
+ return err;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to encode file handle (%pd2, err=%i, buflen=%d, len=%d, type=%d)\n",
+ dentry, err, buflen, fh ? (int)fh->len : 0,
+ fh ? fh->type : 0);
+ goto out;
+}
+
+static int ovl_dentry_to_fh(struct dentry *dentry, u32 *fid, int *max_len)
+{
+ int res, len = *max_len << 2;
+
+ res = ovl_d_to_fh(dentry, (char *)fid, len);
+ if (res <= 0)
+ return FILEID_INVALID;
+
+ len = res;
+
+ /* Round up to dwords */
+ *max_len = (len + 3) >> 2;
+ return OVL_FILEID;
+}
+
+static int ovl_encode_fh(struct inode *inode, u32 *fid, int *max_len,
+ struct inode *parent)
+{
+ struct dentry *dentry;
+ int type;
+
+ /* TODO: encode connectable file handles */
+ if (parent)
+ return FILEID_INVALID;
+
+ dentry = d_find_any_alias(inode);
+ if (WARN_ON(!dentry))
+ return FILEID_INVALID;
+
+ type = ovl_dentry_to_fh(dentry, fid, max_len);
+
+ dput(dentry);
+ return type;
+}
+
+/*
+ * Find or instantiate an overlay dentry from real dentries and index.
+ */
+static struct dentry *ovl_obtain_alias(struct super_block *sb,
+ struct dentry *upper_alias,
+ struct ovl_path *lowerpath,
+ struct dentry *index)
+{
+ struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
+ struct dentry *upper = upper_alias ?: index;
+ struct dentry *dentry;
+ struct inode *inode;
+ struct ovl_entry *oe;
+ struct ovl_inode_params oip = {
+ .lowerpath = lowerpath,
+ .index = index,
+ .numlower = !!lower
+ };
+
+ /* We get overlay directory dentries with ovl_lookup_real() */
+ if (d_is_dir(upper ?: lower))
+ return ERR_PTR(-EIO);
+
+ oip.upperdentry = dget(upper);
+ inode = ovl_get_inode(sb, &oip);
+ if (IS_ERR(inode)) {
+ dput(upper);
+ return ERR_CAST(inode);
+ }
+
+ if (upper)
+ ovl_set_flag(OVL_UPPERDATA, inode);
+
+ dentry = d_find_any_alias(inode);
+ if (!dentry) {
+ dentry = d_alloc_anon(inode->i_sb);
+ if (!dentry)
+ goto nomem;
+ oe = ovl_alloc_entry(lower ? 1 : 0);
+ if (!oe)
+ goto nomem;
+
+ if (lower) {
+ oe->lowerstack->dentry = dget(lower);
+ oe->lowerstack->layer = lowerpath->layer;
+ }
+ dentry->d_fsdata = oe;
+ if (upper_alias)
+ ovl_dentry_set_upper_alias(dentry);
+ }
+
+ return d_instantiate_anon(dentry, inode);
+
+nomem:
+ iput(inode);
+ dput(dentry);
+ return ERR_PTR(-ENOMEM);
+}
+
+/* Get the upper or lower dentry in stach whose on layer @idx */
+static struct dentry *ovl_dentry_real_at(struct dentry *dentry, int idx)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ int i;
+
+ if (!idx)
+ return ovl_dentry_upper(dentry);
+
+ for (i = 0; i < oe->numlower; i++) {
+ if (oe->lowerstack[i].layer->idx == idx)
+ return oe->lowerstack[i].dentry;
+ }
+
+ return NULL;
+}
+
+/*
+ * Lookup a child overlay dentry to get a connected overlay dentry whose real
+ * dentry is @real. If @real is on upper layer, we lookup a child overlay
+ * dentry with the same name as the real dentry. Otherwise, we need to consult
+ * index for lookup.
+ */
+static struct dentry *ovl_lookup_real_one(struct dentry *connected,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct inode *dir = d_inode(connected);
+ struct dentry *this, *parent = NULL;
+ struct name_snapshot name;
+ int err;
+
+ /*
+ * Lookup child overlay dentry by real name. The dir mutex protects us
+ * from racing with overlay rename. If the overlay dentry that is above
+ * real has already been moved to a parent that is not under the
+ * connected overlay dir, we return -ECHILD and restart the lookup of
+ * connected real path from the top.
+ */
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ err = -ECHILD;
+ parent = dget_parent(real);
+ if (ovl_dentry_real_at(connected, layer->idx) != parent)
+ goto fail;
+
+ /*
+ * We also need to take a snapshot of real dentry name to protect us
+ * from racing with underlying layer rename. In this case, we don't
+ * care about returning ESTALE, only from dereferencing a free name
+ * pointer because we hold no lock on the real dentry.
+ */
+ take_dentry_name_snapshot(&name, real);
+ this = lookup_one_len(name.name, connected, strlen(name.name));
+ err = PTR_ERR(this);
+ if (IS_ERR(this)) {
+ goto fail;
+ } else if (!this || !this->d_inode) {
+ dput(this);
+ err = -ENOENT;
+ goto fail;
+ } else if (ovl_dentry_real_at(this, layer->idx) != real) {
+ dput(this);
+ err = -ESTALE;
+ goto fail;
+ }
+
+out:
+ release_dentry_name_snapshot(&name);
+ dput(parent);
+ inode_unlock(dir);
+ return this;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to lookup one by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
+ real, layer->idx, connected, err);
+ this = ERR_PTR(err);
+ goto out;
+}
+
+static struct dentry *ovl_lookup_real(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer);
+
+/*
+ * Lookup an indexed or hashed overlay dentry by real inode.
+ */
+static struct dentry *ovl_lookup_real_inode(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
+ struct dentry *index = NULL;
+ struct dentry *this = NULL;
+ struct inode *inode;
+
+ /*
+ * Decoding upper dir from index is expensive, so first try to lookup
+ * overlay dentry in inode/dcache.
+ */
+ inode = ovl_lookup_inode(sb, real, !layer->idx);
+ if (IS_ERR(inode))
+ return ERR_CAST(inode);
+ if (inode) {
+ this = d_find_any_alias(inode);
+ iput(inode);
+ }
+
+ /*
+ * For decoded lower dir file handle, lookup index by origin to check
+ * if lower dir was copied up and and/or removed.
+ */
+ if (!this && layer->idx && ofs->indexdir && !WARN_ON(!d_is_dir(real))) {
+ index = ovl_lookup_index(ofs, NULL, real, false);
+ if (IS_ERR(index))
+ return index;
+ }
+
+ /* Get connected upper overlay dir from index */
+ if (index) {
+ struct dentry *upper = ovl_index_upper(ofs, index);
+
+ dput(index);
+ if (IS_ERR_OR_NULL(upper))
+ return upper;
+
+ /*
+ * ovl_lookup_real() in lower layer may call recursively once to
+ * ovl_lookup_real() in upper layer. The first level call walks
+ * back lower parents to the topmost indexed parent. The second
+ * recursive call walks back from indexed upper to the topmost
+ * connected/hashed upper parent (or up to root).
+ */
+ this = ovl_lookup_real(sb, upper, &upper_layer);
+ dput(upper);
+ }
+
+ if (IS_ERR_OR_NULL(this))
+ return this;
+
+ if (WARN_ON(ovl_dentry_real_at(this, layer->idx) != real)) {
+ dput(this);
+ this = ERR_PTR(-EIO);
+ }
+
+ return this;
+}
+
+/*
+ * Lookup an indexed or hashed overlay dentry, whose real dentry is an
+ * ancestor of @real.
+ */
+static struct dentry *ovl_lookup_real_ancestor(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct dentry *next, *parent = NULL;
+ struct dentry *ancestor = ERR_PTR(-EIO);
+
+ if (real == layer->mnt->mnt_root)
+ return dget(sb->s_root);
+
+ /* Find the topmost indexed or hashed ancestor */
+ next = dget(real);
+ for (;;) {
+ parent = dget_parent(next);
+
+ /*
+ * Lookup a matching overlay dentry in inode/dentry
+ * cache or in index by real inode.
+ */
+ ancestor = ovl_lookup_real_inode(sb, next, layer);
+ if (ancestor)
+ break;
+
+ if (parent == layer->mnt->mnt_root) {
+ ancestor = dget(sb->s_root);
+ break;
+ }
+
+ /*
+ * If @real has been moved out of the layer root directory,
+ * we will eventully hit the real fs root. This cannot happen
+ * by legit overlay rename, so we return error in that case.
+ */
+ if (parent == next) {
+ ancestor = ERR_PTR(-EXDEV);
+ break;
+ }
+
+ dput(next);
+ next = parent;
+ }
+
+ dput(parent);
+ dput(next);
+
+ return ancestor;
+}
+
+/*
+ * Lookup a connected overlay dentry whose real dentry is @real.
+ * If @real is on upper layer, we lookup a child overlay dentry with the same
+ * path the real dentry. Otherwise, we need to consult index for lookup.
+ */
+static struct dentry *ovl_lookup_real(struct super_block *sb,
+ struct dentry *real,
+ struct ovl_layer *layer)
+{
+ struct dentry *connected;
+ int err = 0;
+
+ connected = ovl_lookup_real_ancestor(sb, real, layer);
+ if (IS_ERR(connected))
+ return connected;
+
+ while (!err) {
+ struct dentry *next, *this;
+ struct dentry *parent = NULL;
+ struct dentry *real_connected = ovl_dentry_real_at(connected,
+ layer->idx);
+
+ if (real_connected == real)
+ break;
+
+ /* Find the topmost dentry not yet connected */
+ next = dget(real);
+ for (;;) {
+ parent = dget_parent(next);
+
+ if (parent == real_connected)
+ break;
+
+ /*
+ * If real has been moved out of 'real_connected',
+ * we will not find 'real_connected' and hit the layer
+ * root. In that case, we need to restart connecting.
+ * This game can go on forever in the worst case. We
+ * may want to consider taking s_vfs_rename_mutex if
+ * this happens more than once.
+ */
+ if (parent == layer->mnt->mnt_root) {
+ dput(connected);
+ connected = dget(sb->s_root);
+ break;
+ }
+
+ /*
+ * If real file has been moved out of the layer root
+ * directory, we will eventully hit the real fs root.
+ * This cannot happen by legit overlay rename, so we
+ * return error in that case.
+ */
+ if (parent == next) {
+ err = -EXDEV;
+ break;
+ }
+
+ dput(next);
+ next = parent;
+ }
+
+ if (!err) {
+ this = ovl_lookup_real_one(connected, next, layer);
+ if (IS_ERR(this))
+ err = PTR_ERR(this);
+
+ /*
+ * Lookup of child in overlay can fail when racing with
+ * overlay rename of child away from 'connected' parent.
+ * In this case, we need to restart the lookup from the
+ * top, because we cannot trust that 'real_connected' is
+ * still an ancestor of 'real'. There is a good chance
+ * that the renamed overlay ancestor is now in cache, so
+ * ovl_lookup_real_ancestor() will find it and we can
+ * continue to connect exactly from where lookup failed.
+ */
+ if (err == -ECHILD) {
+ this = ovl_lookup_real_ancestor(sb, real,
+ layer);
+ err = PTR_ERR_OR_ZERO(this);
+ }
+ if (!err) {
+ dput(connected);
+ connected = this;
+ }
+ }
+
+ dput(parent);
+ dput(next);
+ }
+
+ if (err)
+ goto fail;
+
+ return connected;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to lookup by real (%pd2, layer=%d, connected=%pd2, err=%i)\n",
+ real, layer->idx, connected, err);
+ dput(connected);
+ return ERR_PTR(err);
+}
+
+/*
+ * Get an overlay dentry from upper/lower real dentries and index.
+ */
+static struct dentry *ovl_get_dentry(struct super_block *sb,
+ struct dentry *upper,
+ struct ovl_path *lowerpath,
+ struct dentry *index)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
+ struct ovl_layer *layer = upper ? &upper_layer : lowerpath->layer;
+ struct dentry *real = upper ?: (index ?: lowerpath->dentry);
+
+ /*
+ * Obtain a disconnected overlay dentry from a non-dir real dentry
+ * and index.
+ */
+ if (!d_is_dir(real))
+ return ovl_obtain_alias(sb, upper, lowerpath, index);
+
+ /* Removed empty directory? */
+ if ((real->d_flags & DCACHE_DISCONNECTED) || d_unhashed(real))
+ return ERR_PTR(-ENOENT);
+
+ /*
+ * If real dentry is connected and hashed, get a connected overlay
+ * dentry whose real dentry is @real.
+ */
+ return ovl_lookup_real(sb, real, layer);
+}
+
+static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
+ struct ovl_fh *fh)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct dentry *dentry;
+ struct dentry *upper;
+
+ if (!ofs->upper_mnt)
+ return ERR_PTR(-EACCES);
+
+ upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
+ if (IS_ERR_OR_NULL(upper))
+ return upper;
+
+ dentry = ovl_get_dentry(sb, upper, NULL, NULL);
+ dput(upper);
+
+ return dentry;
+}
+
+static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
+ struct ovl_fh *fh)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct ovl_path origin = { };
+ struct ovl_path *stack = &origin;
+ struct dentry *dentry = NULL;
+ struct dentry *index = NULL;
+ struct inode *inode;
+ int err;
+
+ /* First lookup overlay inode in inode cache by origin fh */
+ err = ovl_check_origin_fh(ofs, fh, false, NULL, &stack);
+ if (err)
+ return ERR_PTR(err);
+
+ if (!d_is_dir(origin.dentry) ||
+ !(origin.dentry->d_flags & DCACHE_DISCONNECTED)) {
+ inode = ovl_lookup_inode(sb, origin.dentry, false);
+ err = PTR_ERR(inode);
+ if (IS_ERR(inode))
+ goto out_err;
+ if (inode) {
+ dentry = d_find_any_alias(inode);
+ iput(inode);
+ if (dentry)
+ goto out;
+ }
+ }
+
+ /* Then lookup indexed upper/whiteout by origin fh */
+ if (ofs->indexdir) {
+ index = ovl_get_index_fh(ofs, fh);
+ err = PTR_ERR(index);
+ if (IS_ERR(index)) {
+ index = NULL;
+ goto out_err;
+ }
+ }
+
+ /* Then try to get a connected upper dir by index */
+ if (index && d_is_dir(index)) {
+ struct dentry *upper = ovl_index_upper(ofs, index);
+
+ err = PTR_ERR(upper);
+ if (IS_ERR_OR_NULL(upper))
+ goto out_err;
+
+ dentry = ovl_get_dentry(sb, upper, NULL, NULL);
+ dput(upper);
+ goto out;
+ }
+
+ /* Find origin.dentry again with ovl_acceptable() layer check */
+ if (d_is_dir(origin.dentry)) {
+ dput(origin.dentry);
+ origin.dentry = NULL;
+ err = ovl_check_origin_fh(ofs, fh, true, NULL, &stack);
+ if (err)
+ goto out_err;
+ }
+ if (index) {
+ err = ovl_verify_origin(index, origin.dentry, false);
+ if (err)
+ goto out_err;
+ }
+
+ /* Get a connected non-upper dir or disconnected non-dir */
+ dentry = ovl_get_dentry(sb, NULL, &origin, index);
+
+out:
+ dput(origin.dentry);
+ dput(index);
+ return dentry;
+
+out_err:
+ dentry = ERR_PTR(err);
+ goto out;
+}
+
+static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ struct dentry *dentry = NULL;
+ struct ovl_fh *fh = (struct ovl_fh *) fid;
+ int len = fh_len << 2;
+ unsigned int flags = 0;
+ int err;
+
+ err = -EINVAL;
+ if (fh_type != OVL_FILEID)
+ goto out_err;
+
+ err = ovl_check_fh_len(fh, len);
+ if (err)
+ goto out_err;
+
+ flags = fh->flags;
+ dentry = (flags & OVL_FH_FLAG_PATH_UPPER) ?
+ ovl_upper_fh_to_d(sb, fh) :
+ ovl_lower_fh_to_d(sb, fh);
+ err = PTR_ERR(dentry);
+ if (IS_ERR(dentry) && err != -ESTALE)
+ goto out_err;
+
+ return dentry;
+
+out_err:
+ pr_warn_ratelimited("overlayfs: failed to decode file handle (len=%d, type=%d, flags=%x, err=%i)\n",
+ len, fh_type, flags, err);
+ return ERR_PTR(err);
+}
+
+static struct dentry *ovl_fh_to_parent(struct super_block *sb, struct fid *fid,
+ int fh_len, int fh_type)
+{
+ pr_warn_ratelimited("overlayfs: connectable file handles not supported; use 'no_subtree_check' exportfs option.\n");
+ return ERR_PTR(-EACCES);
+}
+
+static int ovl_get_name(struct dentry *parent, char *name,
+ struct dentry *child)
+{
+ /*
+ * ovl_fh_to_dentry() returns connected dir overlay dentries and
+ * ovl_fh_to_parent() is not implemented, so we should not get here.
+ */
+ WARN_ON_ONCE(1);
+ return -EIO;
+}
+
+static struct dentry *ovl_get_parent(struct dentry *dentry)
+{
+ /*
+ * ovl_fh_to_dentry() returns connected dir overlay dentries, so we
+ * should not get here.
+ */
+ WARN_ON_ONCE(1);
+ return ERR_PTR(-EIO);
+}
+
+const struct export_operations ovl_export_operations = {
+ .encode_fh = ovl_encode_fh,
+ .fh_to_dentry = ovl_fh_to_dentry,
+ .fh_to_parent = ovl_fh_to_parent,
+ .get_name = ovl_get_name,
+ .get_parent = ovl_get_parent,
+};
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
new file mode 100644
index 0000000..986313d
--- /dev/null
+++ b/fs/overlayfs/file.c
@@ -0,0 +1,530 @@
+/*
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/cred.h>
+#include <linux/file.h>
+#include <linux/mount.h>
+#include <linux/xattr.h>
+#include <linux/uio.h>
+#include "overlayfs.h"
+
+static char ovl_whatisit(struct inode *inode, struct inode *realinode)
+{
+ if (realinode != ovl_inode_upper(inode))
+ return 'l';
+ if (ovl_has_upperdata(inode))
+ return 'u';
+ else
+ return 'm';
+}
+
+static struct file *ovl_open_realfile(const struct file *file,
+ struct inode *realinode)
+{
+ struct inode *inode = file_inode(file);
+ struct file *realfile;
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(inode->i_sb);
+ realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
+ realinode, current_cred());
+ revert_creds(old_cred);
+
+ pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
+ file, file, ovl_whatisit(inode, realinode), file->f_flags,
+ realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
+
+ return realfile;
+}
+
+#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
+
+static int ovl_change_flags(struct file *file, unsigned int flags)
+{
+ struct inode *inode = file_inode(file);
+ int err;
+
+ /* No atime modificaton on underlying */
+ flags |= O_NOATIME;
+
+ /* If some flag changed that cannot be changed then something's amiss */
+ if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
+ return -EIO;
+
+ flags &= OVL_SETFL_MASK;
+
+ if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
+ return -EPERM;
+
+ if (flags & O_DIRECT) {
+ if (!file->f_mapping->a_ops ||
+ !file->f_mapping->a_ops->direct_IO)
+ return -EINVAL;
+ }
+
+ if (file->f_op->check_flags) {
+ err = file->f_op->check_flags(flags);
+ if (err)
+ return err;
+ }
+
+ spin_lock(&file->f_lock);
+ file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
+ spin_unlock(&file->f_lock);
+
+ return 0;
+}
+
+static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
+ bool allow_meta)
+{
+ struct inode *inode = file_inode(file);
+ struct inode *realinode;
+
+ real->flags = 0;
+ real->file = file->private_data;
+
+ if (allow_meta)
+ realinode = ovl_inode_real(inode);
+ else
+ realinode = ovl_inode_realdata(inode);
+
+ /* Has it been copied up since we'd opened it? */
+ if (unlikely(file_inode(real->file) != realinode)) {
+ real->flags = FDPUT_FPUT;
+ real->file = ovl_open_realfile(file, realinode);
+
+ return PTR_ERR_OR_ZERO(real->file);
+ }
+
+ /* Did the flags change since open? */
+ if (unlikely((file->f_flags ^ real->file->f_flags) & ~O_NOATIME))
+ return ovl_change_flags(real->file, file->f_flags);
+
+ return 0;
+}
+
+static int ovl_real_fdget(const struct file *file, struct fd *real)
+{
+ return ovl_real_fdget_meta(file, real, false);
+}
+
+static int ovl_open(struct inode *inode, struct file *file)
+{
+ struct dentry *dentry = file_dentry(file);
+ struct file *realfile;
+ int err;
+
+ err = ovl_open_maybe_copy_up(dentry, file->f_flags);
+ if (err)
+ return err;
+
+ /* No longer need these flags, so don't pass them on to underlying fs */
+ file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+
+ realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ file->private_data = realfile;
+
+ return 0;
+}
+
+static int ovl_release(struct inode *inode, struct file *file)
+{
+ fput(file->private_data);
+
+ return 0;
+}
+
+static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *realinode = ovl_inode_real(file_inode(file));
+
+ return generic_file_llseek_size(file, offset, whence,
+ realinode->i_sb->s_maxbytes,
+ i_size_read(realinode));
+}
+
+static void ovl_file_accessed(struct file *file)
+{
+ struct inode *inode, *upperinode;
+
+ if (file->f_flags & O_NOATIME)
+ return;
+
+ inode = file_inode(file);
+ upperinode = ovl_inode_upper(inode);
+
+ if (!upperinode)
+ return;
+
+ if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
+ !timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
+ inode->i_mtime = upperinode->i_mtime;
+ inode->i_ctime = upperinode->i_ctime;
+ }
+
+ touch_atime(&file->f_path);
+}
+
+static rwf_t ovl_iocb_to_rwf(struct kiocb *iocb)
+{
+ int ifl = iocb->ki_flags;
+ rwf_t flags = 0;
+
+ if (ifl & IOCB_NOWAIT)
+ flags |= RWF_NOWAIT;
+ if (ifl & IOCB_HIPRI)
+ flags |= RWF_HIPRI;
+ if (ifl & IOCB_DSYNC)
+ flags |= RWF_DSYNC;
+ if (ifl & IOCB_SYNC)
+ flags |= RWF_SYNC;
+
+ return flags;
+}
+
+static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct fd real;
+ const struct cred *old_cred;
+ ssize_t ret;
+
+ if (!iov_iter_count(iter))
+ return 0;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
+ ovl_iocb_to_rwf(iocb));
+ revert_creds(old_cred);
+
+ ovl_file_accessed(file);
+
+ fdput(real);
+
+ return ret;
+}
+
+static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
+{
+ struct file *file = iocb->ki_filp;
+ struct inode *inode = file_inode(file);
+ struct fd real;
+ const struct cred *old_cred;
+ ssize_t ret;
+
+ if (!iov_iter_count(iter))
+ return 0;
+
+ inode_lock(inode);
+ /* Update mode */
+ ovl_copyattr(ovl_inode_real(inode), inode);
+ ret = file_remove_privs(file);
+ if (ret)
+ goto out_unlock;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ goto out_unlock;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ file_start_write(real.file);
+ ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
+ ovl_iocb_to_rwf(iocb));
+ file_end_write(real.file);
+ revert_creds(old_cred);
+
+ /* Update size */
+ ovl_copyattr(ovl_inode_real(inode), inode);
+
+ fdput(real);
+
+out_unlock:
+ inode_unlock(inode);
+
+ return ret;
+}
+
+static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
+{
+ struct fd real;
+ const struct cred *old_cred;
+ int ret;
+
+ ret = ovl_real_fdget_meta(file, &real, !datasync);
+ if (ret)
+ return ret;
+
+ /* Don't sync lower file for fear of receiving EROFS error */
+ if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_fsync_range(real.file, start, end, datasync);
+ revert_creds(old_cred);
+ }
+
+ fdput(real);
+
+ return ret;
+}
+
+static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ struct file *realfile = file->private_data;
+ const struct cred *old_cred;
+ int ret;
+
+ if (!realfile->f_op->mmap)
+ return -ENODEV;
+
+ if (WARN_ON(file != vma->vm_file))
+ return -EIO;
+
+ vma->vm_file = get_file(realfile);
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = call_mmap(vma->vm_file, vma);
+ revert_creds(old_cred);
+
+ if (ret) {
+ /* Drop reference count from new vm_file value */
+ fput(realfile);
+ } else {
+ /* Drop reference count from previous vm_file value */
+ fput(file);
+ }
+
+ ovl_file_accessed(file);
+
+ return ret;
+}
+
+static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
+{
+ struct inode *inode = file_inode(file);
+ struct fd real;
+ const struct cred *old_cred;
+ int ret;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_fallocate(real.file, mode, offset, len);
+ revert_creds(old_cred);
+
+ /* Update size */
+ ovl_copyattr(ovl_inode_real(inode), inode);
+
+ fdput(real);
+
+ return ret;
+}
+
+static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
+{
+ struct fd real;
+ const struct cred *old_cred;
+ int ret;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_fadvise(real.file, offset, len, advice);
+ revert_creds(old_cred);
+
+ fdput(real);
+
+ return ret;
+}
+
+static long ovl_real_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct fd real;
+ const struct cred *old_cred;
+ long ret;
+
+ ret = ovl_real_fdget(file, &real);
+ if (ret)
+ return ret;
+
+ old_cred = ovl_override_creds(file_inode(file)->i_sb);
+ ret = vfs_ioctl(real.file, cmd, arg);
+ revert_creds(old_cred);
+
+ fdput(real);
+
+ return ret;
+}
+
+static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+ long ret;
+ struct inode *inode = file_inode(file);
+
+ switch (cmd) {
+ case FS_IOC_GETFLAGS:
+ ret = ovl_real_ioctl(file, cmd, arg);
+ break;
+
+ case FS_IOC_SETFLAGS:
+ if (!inode_owner_or_capable(inode))
+ return -EACCES;
+
+ ret = mnt_want_write_file(file);
+ if (ret)
+ return ret;
+
+ ret = ovl_copy_up_with_data(file_dentry(file));
+ if (!ret) {
+ ret = ovl_real_ioctl(file, cmd, arg);
+
+ inode_lock(inode);
+ ovl_copyflags(ovl_inode_real(inode), inode);
+ inode_unlock(inode);
+ }
+
+ mnt_drop_write_file(file);
+ break;
+
+ default:
+ ret = -ENOTTY;
+ }
+
+ return ret;
+}
+
+static long ovl_compat_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ switch (cmd) {
+ case FS_IOC32_GETFLAGS:
+ cmd = FS_IOC_GETFLAGS;
+ break;
+
+ case FS_IOC32_SETFLAGS:
+ cmd = FS_IOC_SETFLAGS;
+ break;
+
+ default:
+ return -ENOIOCTLCMD;
+ }
+
+ return ovl_ioctl(file, cmd, arg);
+}
+
+enum ovl_copyop {
+ OVL_COPY,
+ OVL_CLONE,
+ OVL_DEDUPE,
+};
+
+static ssize_t ovl_copyfile(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ u64 len, unsigned int flags, enum ovl_copyop op)
+{
+ struct inode *inode_out = file_inode(file_out);
+ struct fd real_in, real_out;
+ const struct cred *old_cred;
+ ssize_t ret;
+
+ ret = ovl_real_fdget(file_out, &real_out);
+ if (ret)
+ return ret;
+
+ ret = ovl_real_fdget(file_in, &real_in);
+ if (ret) {
+ fdput(real_out);
+ return ret;
+ }
+
+ old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
+ switch (op) {
+ case OVL_COPY:
+ ret = vfs_copy_file_range(real_in.file, pos_in,
+ real_out.file, pos_out, len, flags);
+ break;
+
+ case OVL_CLONE:
+ ret = vfs_clone_file_range(real_in.file, pos_in,
+ real_out.file, pos_out, len);
+ break;
+
+ case OVL_DEDUPE:
+ ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
+ real_out.file, pos_out, len);
+ break;
+ }
+ revert_creds(old_cred);
+
+ /* Update size */
+ ovl_copyattr(ovl_inode_real(inode_out), inode_out);
+
+ fdput(real_in);
+ fdput(real_out);
+
+ return ret;
+}
+
+static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out,
+ size_t len, unsigned int flags)
+{
+ return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
+ OVL_COPY);
+}
+
+static int ovl_clone_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out, u64 len)
+{
+ return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
+ OVL_CLONE);
+}
+
+static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in,
+ struct file *file_out, loff_t pos_out, u64 len)
+{
+ /*
+ * Don't copy up because of a dedupe request, this wouldn't make sense
+ * most of the time (data would be duplicated instead of deduplicated).
+ */
+ if (!ovl_inode_upper(file_inode(file_in)) ||
+ !ovl_inode_upper(file_inode(file_out)))
+ return -EPERM;
+
+ return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
+ OVL_DEDUPE);
+}
+
+const struct file_operations ovl_file_operations = {
+ .open = ovl_open,
+ .release = ovl_release,
+ .llseek = ovl_llseek,
+ .read_iter = ovl_read_iter,
+ .write_iter = ovl_write_iter,
+ .fsync = ovl_fsync,
+ .mmap = ovl_mmap,
+ .fallocate = ovl_fallocate,
+ .fadvise = ovl_fadvise,
+ .unlocked_ioctl = ovl_ioctl,
+ .compat_ioctl = ovl_compat_ioctl,
+
+ .copy_file_range = ovl_copy_file_range,
+ .clone_file_range = ovl_clone_file_range,
+ .dedupe_file_range = ovl_dedupe_file_range,
+};
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
new file mode 100644
index 0000000..3b7ed5d
--- /dev/null
+++ b/fs/overlayfs/inode.c
@@ -0,0 +1,922 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/xattr.h>
+#include <linux/posix_acl.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+
+int ovl_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ int err;
+ bool full_copy_up = false;
+ struct dentry *upperdentry;
+ const struct cred *old_cred;
+
+ err = setattr_prepare(dentry, attr);
+ if (err)
+ return err;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ if (attr->ia_valid & ATTR_SIZE) {
+ struct inode *realinode = d_inode(ovl_dentry_real(dentry));
+
+ err = -ETXTBSY;
+ if (atomic_read(&realinode->i_writecount) < 0)
+ goto out_drop_write;
+
+ /* Truncate should trigger data copy up as well */
+ full_copy_up = true;
+ }
+
+ if (!full_copy_up)
+ err = ovl_copy_up(dentry);
+ else
+ err = ovl_copy_up_with_data(dentry);
+ if (!err) {
+ struct inode *winode = NULL;
+
+ upperdentry = ovl_dentry_upper(dentry);
+
+ if (attr->ia_valid & ATTR_SIZE) {
+ winode = d_inode(upperdentry);
+ err = get_write_access(winode);
+ if (err)
+ goto out_drop_write;
+ }
+
+ if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
+ attr->ia_valid &= ~ATTR_MODE;
+
+ inode_lock(upperdentry->d_inode);
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = notify_change(upperdentry, attr, NULL);
+ revert_creds(old_cred);
+ if (!err)
+ ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
+ inode_unlock(upperdentry->d_inode);
+
+ if (winode)
+ put_write_access(winode);
+ }
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+static int ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat,
+ struct ovl_layer *lower_layer)
+{
+ bool samefs = ovl_same_sb(dentry->d_sb);
+ unsigned int xinobits = ovl_xino_bits(dentry->d_sb);
+
+ if (samefs) {
+ /*
+ * When all layers are on the same fs, all real inode
+ * number are unique, so we use the overlay st_dev,
+ * which is friendly to du -x.
+ */
+ stat->dev = dentry->d_sb->s_dev;
+ return 0;
+ } else if (xinobits) {
+ unsigned int shift = 64 - xinobits;
+ /*
+ * All inode numbers of underlying fs should not be using the
+ * high xinobits, so we use high xinobits to partition the
+ * overlay st_ino address space. The high bits holds the fsid
+ * (upper fsid is 0). This way overlay inode numbers are unique
+ * and all inodes use overlay st_dev. Inode numbers are also
+ * persistent for a given layer configuration.
+ */
+ if (stat->ino >> shift) {
+ pr_warn_ratelimited("overlayfs: inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
+ dentry, stat->ino, xinobits);
+ } else {
+ if (lower_layer)
+ stat->ino |= ((u64)lower_layer->fsid) << shift;
+
+ stat->dev = dentry->d_sb->s_dev;
+ return 0;
+ }
+ }
+
+ /* The inode could not be mapped to a unified st_ino address space */
+ if (S_ISDIR(dentry->d_inode->i_mode)) {
+ /*
+ * Always use the overlay st_dev for directories, so 'find
+ * -xdev' will scan the entire overlay mount and won't cross the
+ * overlay mount boundaries.
+ *
+ * If not all layers are on the same fs the pair {real st_ino;
+ * overlay st_dev} is not unique, so use the non persistent
+ * overlay st_ino for directories.
+ */
+ stat->dev = dentry->d_sb->s_dev;
+ stat->ino = dentry->d_inode->i_ino;
+ } else if (lower_layer && lower_layer->fsid) {
+ /*
+ * For non-samefs setup, if we cannot map all layers st_ino
+ * to a unified address space, we need to make sure that st_dev
+ * is unique per lower fs. Upper layer uses real st_dev and
+ * lower layers use the unique anonymous bdev assigned to the
+ * lower fs.
+ */
+ stat->dev = lower_layer->fs->pseudo_dev;
+ }
+
+ return 0;
+}
+
+int ovl_getattr(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int flags)
+{
+ struct dentry *dentry = path->dentry;
+ enum ovl_path_type type;
+ struct path realpath;
+ const struct cred *old_cred;
+ bool is_dir = S_ISDIR(dentry->d_inode->i_mode);
+ bool samefs = ovl_same_sb(dentry->d_sb);
+ struct ovl_layer *lower_layer = NULL;
+ int err;
+ bool metacopy_blocks = false;
+
+ metacopy_blocks = ovl_is_metacopy_dentry(dentry);
+
+ type = ovl_path_real(dentry, &realpath);
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = vfs_getattr(&realpath, stat, request_mask, flags);
+ if (err)
+ goto out;
+
+ /*
+ * For non-dir or same fs, we use st_ino of the copy up origin.
+ * This guaranties constant st_dev/st_ino across copy up.
+ * With xino feature and non-samefs, we use st_ino of the copy up
+ * origin masked with high bits that represent the layer id.
+ *
+ * If lower filesystem supports NFS file handles, this also guaranties
+ * persistent st_ino across mount cycle.
+ */
+ if (!is_dir || samefs || ovl_xino_bits(dentry->d_sb)) {
+ if (!OVL_TYPE_UPPER(type)) {
+ lower_layer = ovl_layer_lower(dentry);
+ } else if (OVL_TYPE_ORIGIN(type)) {
+ struct kstat lowerstat;
+ u32 lowermask = STATX_INO | STATX_BLOCKS |
+ (!is_dir ? STATX_NLINK : 0);
+
+ ovl_path_lower(dentry, &realpath);
+ err = vfs_getattr(&realpath, &lowerstat,
+ lowermask, flags);
+ if (err)
+ goto out;
+
+ /*
+ * Lower hardlinks may be broken on copy up to different
+ * upper files, so we cannot use the lower origin st_ino
+ * for those different files, even for the same fs case.
+ *
+ * Similarly, several redirected dirs can point to the
+ * same dir on a lower layer. With the "verify_lower"
+ * feature, we do not use the lower origin st_ino, if
+ * we haven't verified that this redirect is unique.
+ *
+ * With inodes index enabled, it is safe to use st_ino
+ * of an indexed origin. The index validates that the
+ * upper hardlink is not broken and that a redirected
+ * dir is the only redirect to that origin.
+ */
+ if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
+ (!ovl_verify_lower(dentry->d_sb) &&
+ (is_dir || lowerstat.nlink == 1))) {
+ stat->ino = lowerstat.ino;
+ lower_layer = ovl_layer_lower(dentry);
+ }
+
+ /*
+ * If we are querying a metacopy dentry and lower
+ * dentry is data dentry, then use the blocks we
+ * queried just now. We don't have to do additional
+ * vfs_getattr(). If lower itself is metacopy, then
+ * additional vfs_getattr() is unavoidable.
+ */
+ if (metacopy_blocks &&
+ realpath.dentry == ovl_dentry_lowerdata(dentry)) {
+ stat->blocks = lowerstat.blocks;
+ metacopy_blocks = false;
+ }
+ }
+
+ if (metacopy_blocks) {
+ /*
+ * If lower is not same as lowerdata or if there was
+ * no origin on upper, we can end up here.
+ */
+ struct kstat lowerdatastat;
+ u32 lowermask = STATX_BLOCKS;
+
+ ovl_path_lowerdata(dentry, &realpath);
+ err = vfs_getattr(&realpath, &lowerdatastat,
+ lowermask, flags);
+ if (err)
+ goto out;
+ stat->blocks = lowerdatastat.blocks;
+ }
+ }
+
+ err = ovl_map_dev_ino(dentry, stat, lower_layer);
+ if (err)
+ goto out;
+
+ /*
+ * It's probably not worth it to count subdirs to get the
+ * correct link count. nlink=1 seems to pacify 'find' and
+ * other utilities.
+ */
+ if (is_dir && OVL_TYPE_MERGE(type))
+ stat->nlink = 1;
+
+ /*
+ * Return the overlay inode nlinks for indexed upper inodes.
+ * Overlay inode nlink counts the union of the upper hardlinks
+ * and non-covered lower hardlinks. It does not include the upper
+ * index hardlink.
+ */
+ if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+ stat->nlink = dentry->d_inode->i_nlink;
+
+out:
+ revert_creds(old_cred);
+
+ return err;
+}
+
+int ovl_permission(struct inode *inode, int mask)
+{
+ struct inode *upperinode = ovl_inode_upper(inode);
+ struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
+ const struct cred *old_cred;
+ int err;
+
+ /* Careful in RCU walk mode */
+ if (!realinode) {
+ WARN_ON(!(mask & MAY_NOT_BLOCK));
+ return -ECHILD;
+ }
+
+ /*
+ * Check overlay inode with the creds of task and underlying inode
+ * with creds of mounter
+ */
+ err = generic_permission(inode, mask);
+ if (err)
+ return err;
+
+ old_cred = ovl_override_creds(inode->i_sb);
+ if (!upperinode &&
+ !special_file(realinode->i_mode) && mask & MAY_WRITE) {
+ mask &= ~(MAY_WRITE | MAY_APPEND);
+ /* Make sure mounter can read file for copy up later */
+ mask |= MAY_READ;
+ }
+ err = inode_permission(realinode, mask);
+ revert_creds(old_cred);
+
+ return err;
+}
+
+static const char *ovl_get_link(struct dentry *dentry,
+ struct inode *inode,
+ struct delayed_call *done)
+{
+ const struct cred *old_cred;
+ const char *p;
+
+ if (!dentry)
+ return ERR_PTR(-ECHILD);
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ p = vfs_get_link(ovl_dentry_real(dentry), done);
+ revert_creds(old_cred);
+ return p;
+}
+
+bool ovl_is_private_xattr(const char *name)
+{
+ return strncmp(name, OVL_XATTR_PREFIX,
+ sizeof(OVL_XATTR_PREFIX) - 1) == 0;
+}
+
+int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err;
+ struct dentry *upperdentry = ovl_i_dentry_upper(inode);
+ struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
+ const struct cred *old_cred;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ goto out;
+
+ if (!value && !upperdentry) {
+ err = vfs_getxattr(realdentry, name, NULL, 0);
+ if (err < 0)
+ goto out_drop_write;
+ }
+
+ if (!upperdentry) {
+ err = ovl_copy_up(dentry);
+ if (err)
+ goto out_drop_write;
+
+ realdentry = ovl_dentry_upper(dentry);
+ }
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ if (value)
+ err = vfs_setxattr(realdentry, name, value, size, flags);
+ else {
+ WARN_ON(flags != XATTR_REPLACE);
+ err = vfs_removexattr(realdentry, name);
+ }
+ revert_creds(old_cred);
+
+ /* copy c/mtime */
+ ovl_copyattr(d_inode(realdentry), inode);
+
+out_drop_write:
+ ovl_drop_write(dentry);
+out:
+ return err;
+}
+
+int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
+ void *value, size_t size)
+{
+ ssize_t res;
+ const struct cred *old_cred;
+ struct dentry *realdentry =
+ ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry);
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ res = vfs_getxattr(realdentry, name, value, size);
+ revert_creds(old_cred);
+ return res;
+}
+
+static bool ovl_can_list(const char *s)
+{
+ /* List all non-trusted xatts */
+ if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0)
+ return true;
+
+ /* Never list trusted.overlay, list other trusted for superuser only */
+ return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN);
+}
+
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ struct dentry *realdentry = ovl_dentry_real(dentry);
+ ssize_t res;
+ size_t len;
+ char *s;
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ res = vfs_listxattr(realdentry, list, size);
+ revert_creds(old_cred);
+ if (res <= 0 || size == 0)
+ return res;
+
+ /* filter out private xattrs */
+ for (s = list, len = res; len;) {
+ size_t slen = strnlen(s, len) + 1;
+
+ /* underlying fs providing us with an broken xattr list? */
+ if (WARN_ON(slen > len))
+ return -EIO;
+
+ len -= slen;
+ if (!ovl_can_list(s)) {
+ res -= slen;
+ memmove(s, s + slen, len);
+ } else {
+ s += slen;
+ }
+ }
+
+ return res;
+}
+
+struct posix_acl *ovl_get_acl(struct inode *inode, int type)
+{
+ struct inode *realinode = ovl_inode_real(inode);
+ const struct cred *old_cred;
+ struct posix_acl *acl;
+
+ if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode))
+ return NULL;
+
+ old_cred = ovl_override_creds(inode->i_sb);
+ acl = get_acl(realinode, type);
+ revert_creds(old_cred);
+
+ return acl;
+}
+
+int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags)
+{
+ if (flags & S_ATIME) {
+ struct ovl_fs *ofs = inode->i_sb->s_fs_info;
+ struct path upperpath = {
+ .mnt = ofs->upper_mnt,
+ .dentry = ovl_upperdentry_dereference(OVL_I(inode)),
+ };
+
+ if (upperpath.dentry) {
+ touch_atime(&upperpath);
+ inode->i_atime = d_inode(upperpath.dentry)->i_atime;
+ }
+ }
+ return 0;
+}
+
+static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+ u64 start, u64 len)
+{
+ int err;
+ struct inode *realinode = ovl_inode_real(inode);
+ const struct cred *old_cred;
+
+ if (!realinode->i_op->fiemap)
+ return -EOPNOTSUPP;
+
+ old_cred = ovl_override_creds(inode->i_sb);
+
+ if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
+ filemap_write_and_wait(realinode->i_mapping);
+
+ err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
+ revert_creds(old_cred);
+
+ return err;
+}
+
+static const struct inode_operations ovl_file_inode_operations = {
+ .setattr = ovl_setattr,
+ .permission = ovl_permission,
+ .getattr = ovl_getattr,
+ .listxattr = ovl_listxattr,
+ .get_acl = ovl_get_acl,
+ .update_time = ovl_update_time,
+ .fiemap = ovl_fiemap,
+};
+
+static const struct inode_operations ovl_symlink_inode_operations = {
+ .setattr = ovl_setattr,
+ .get_link = ovl_get_link,
+ .getattr = ovl_getattr,
+ .listxattr = ovl_listxattr,
+ .update_time = ovl_update_time,
+};
+
+static const struct inode_operations ovl_special_inode_operations = {
+ .setattr = ovl_setattr,
+ .permission = ovl_permission,
+ .getattr = ovl_getattr,
+ .listxattr = ovl_listxattr,
+ .get_acl = ovl_get_acl,
+ .update_time = ovl_update_time,
+};
+
+static const struct address_space_operations ovl_aops = {
+ /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
+ .direct_IO = noop_direct_IO,
+};
+
+/*
+ * It is possible to stack overlayfs instance on top of another
+ * overlayfs instance as lower layer. We need to annonate the
+ * stackable i_mutex locks according to stack level of the super
+ * block instance. An overlayfs instance can never be in stack
+ * depth 0 (there is always a real fs below it). An overlayfs
+ * inode lock will use the lockdep annotaion ovl_i_mutex_key[depth].
+ *
+ * For example, here is a snip from /proc/lockdep_chains after
+ * dir_iterate of nested overlayfs:
+ *
+ * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
+ * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
+ * [...] &type->i_mutex_dir_key (stack_depth=0)
+ */
+#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
+
+static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
+{
+#ifdef CONFIG_LOCKDEP
+ static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING];
+ static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING];
+ static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING];
+
+ int depth = inode->i_sb->s_stack_depth - 1;
+
+ if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING))
+ depth = 0;
+
+ if (S_ISDIR(inode->i_mode))
+ lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]);
+ else
+ lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]);
+
+ lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]);
+#endif
+}
+
+static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
+ unsigned long ino, int fsid)
+{
+ int xinobits = ovl_xino_bits(inode->i_sb);
+
+ /*
+ * When NFS export is enabled and d_ino is consistent with st_ino
+ * (samefs or i_ino has enough bits to encode layer), set the same
+ * value used for d_ino to i_ino, because nfsd readdirplus compares
+ * d_ino values to i_ino values of child entries. When called from
+ * ovl_new_inode(), ino arg is 0, so i_ino will be updated to real
+ * upper inode i_ino on ovl_inode_init() or ovl_inode_update().
+ */
+ if (inode->i_sb->s_export_op &&
+ (ovl_same_sb(inode->i_sb) || xinobits)) {
+ inode->i_ino = ino;
+ if (xinobits && fsid && !(ino >> (64 - xinobits)))
+ inode->i_ino |= (unsigned long)fsid << (64 - xinobits);
+ } else {
+ inode->i_ino = get_next_ino();
+ }
+ inode->i_mode = mode;
+ inode->i_flags |= S_NOCMTIME;
+#ifdef CONFIG_FS_POSIX_ACL
+ inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
+#endif
+
+ ovl_lockdep_annotate_inode_mutex_key(inode);
+
+ switch (mode & S_IFMT) {
+ case S_IFREG:
+ inode->i_op = &ovl_file_inode_operations;
+ inode->i_fop = &ovl_file_operations;
+ inode->i_mapping->a_ops = &ovl_aops;
+ break;
+
+ case S_IFDIR:
+ inode->i_op = &ovl_dir_inode_operations;
+ inode->i_fop = &ovl_dir_operations;
+ break;
+
+ case S_IFLNK:
+ inode->i_op = &ovl_symlink_inode_operations;
+ break;
+
+ default:
+ inode->i_op = &ovl_special_inode_operations;
+ init_special_inode(inode, mode, rdev);
+ break;
+ }
+}
+
+/*
+ * With inodes index enabled, an overlay inode nlink counts the union of upper
+ * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
+ * upper inode, the following nlink modifying operations can happen:
+ *
+ * 1. Lower hardlink copy up
+ * 2. Upper hardlink created, unlinked or renamed over
+ * 3. Lower hardlink whiteout or renamed over
+ *
+ * For the first, copy up case, the union nlink does not change, whether the
+ * operation succeeds or fails, but the upper inode nlink may change.
+ * Therefore, before copy up, we store the union nlink value relative to the
+ * lower inode nlink in the index inode xattr trusted.overlay.nlink.
+ *
+ * For the second, upper hardlink case, the union nlink should be incremented
+ * or decremented IFF the operation succeeds, aligned with nlink change of the
+ * upper inode. Therefore, before link/unlink/rename, we store the union nlink
+ * value relative to the upper inode nlink in the index inode.
+ *
+ * For the last, lower cover up case, we simplify things by preceding the
+ * whiteout or cover up with copy up. This makes sure that there is an index
+ * upper inode where the nlink xattr can be stored before the copied up upper
+ * entry is unlink.
+ */
+#define OVL_NLINK_ADD_UPPER (1 << 0)
+
+/*
+ * On-disk format for indexed nlink:
+ *
+ * nlink relative to the upper inode - "U[+-]NUM"
+ * nlink relative to the lower inode - "L[+-]NUM"
+ */
+
+static int ovl_set_nlink_common(struct dentry *dentry,
+ struct dentry *realdentry, const char *format)
+{
+ struct inode *inode = d_inode(dentry);
+ struct inode *realinode = d_inode(realdentry);
+ char buf[13];
+ int len;
+
+ len = snprintf(buf, sizeof(buf), format,
+ (int) (inode->i_nlink - realinode->i_nlink));
+
+ if (WARN_ON(len >= sizeof(buf)))
+ return -EIO;
+
+ return ovl_do_setxattr(ovl_dentry_upper(dentry),
+ OVL_XATTR_NLINK, buf, len, 0);
+}
+
+int ovl_set_nlink_upper(struct dentry *dentry)
+{
+ return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
+}
+
+int ovl_set_nlink_lower(struct dentry *dentry)
+{
+ return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
+}
+
+unsigned int ovl_get_nlink(struct dentry *lowerdentry,
+ struct dentry *upperdentry,
+ unsigned int fallback)
+{
+ int nlink_diff;
+ int nlink;
+ char buf[13];
+ int err;
+
+ if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
+ return fallback;
+
+ err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1);
+ if (err < 0)
+ goto fail;
+
+ buf[err] = '\0';
+ if ((buf[0] != 'L' && buf[0] != 'U') ||
+ (buf[1] != '+' && buf[1] != '-'))
+ goto fail;
+
+ err = kstrtoint(buf + 1, 10, &nlink_diff);
+ if (err < 0)
+ goto fail;
+
+ nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
+ nlink += nlink_diff;
+
+ if (nlink <= 0)
+ goto fail;
+
+ return nlink;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n",
+ upperdentry, err);
+ return fallback;
+}
+
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
+{
+ struct inode *inode;
+
+ inode = new_inode(sb);
+ if (inode)
+ ovl_fill_inode(inode, mode, rdev, 0, 0);
+
+ return inode;
+}
+
+static int ovl_inode_test(struct inode *inode, void *data)
+{
+ return inode->i_private == data;
+}
+
+static int ovl_inode_set(struct inode *inode, void *data)
+{
+ inode->i_private = data;
+ return 0;
+}
+
+static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
+ struct dentry *upperdentry, bool strict)
+{
+ /*
+ * For directories, @strict verify from lookup path performs consistency
+ * checks, so NULL lower/upper in dentry must match NULL lower/upper in
+ * inode. Non @strict verify from NFS handle decode path passes NULL for
+ * 'unknown' lower/upper.
+ */
+ if (S_ISDIR(inode->i_mode) && strict) {
+ /* Real lower dir moved to upper layer under us? */
+ if (!lowerdentry && ovl_inode_lower(inode))
+ return false;
+
+ /* Lookup of an uncovered redirect origin? */
+ if (!upperdentry && ovl_inode_upper(inode))
+ return false;
+ }
+
+ /*
+ * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
+ * This happens when finding a copied up overlay inode for a renamed
+ * or hardlinked overlay dentry and lower dentry cannot be followed
+ * by origin because lower fs does not support file handles.
+ */
+ if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
+ return false;
+
+ /*
+ * Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
+ * This happens when finding a lower alias for a copied up hard link.
+ */
+ if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
+ return false;
+
+ return true;
+}
+
+struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
+ bool is_upper)
+{
+ struct inode *inode, *key = d_inode(real);
+
+ inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
+ if (!inode)
+ return NULL;
+
+ if (!ovl_verify_inode(inode, is_upper ? NULL : real,
+ is_upper ? real : NULL, false)) {
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+
+ return inode;
+}
+
+/*
+ * Does overlay inode need to be hashed by lower inode?
+ */
+static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
+ struct dentry *lower, struct dentry *index)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ /* No, if pure upper */
+ if (!lower)
+ return false;
+
+ /* Yes, if already indexed */
+ if (index)
+ return true;
+
+ /* Yes, if won't be copied up */
+ if (!ofs->upper_mnt)
+ return true;
+
+ /* No, if lower hardlink is or will be broken on copy up */
+ if ((upper || !ovl_indexdir(sb)) &&
+ !d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
+ return false;
+
+ /* No, if non-indexed upper with NFS export */
+ if (sb->s_export_op && upper)
+ return false;
+
+ /* Otherwise, hash by lower inode for fsnotify */
+ return true;
+}
+
+static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode,
+ struct inode *key)
+{
+ return newinode ? inode_insert5(newinode, (unsigned long) key,
+ ovl_inode_test, ovl_inode_set, key) :
+ iget5_locked(sb, (unsigned long) key,
+ ovl_inode_test, ovl_inode_set, key);
+}
+
+struct inode *ovl_get_inode(struct super_block *sb,
+ struct ovl_inode_params *oip)
+{
+ struct dentry *upperdentry = oip->upperdentry;
+ struct ovl_path *lowerpath = oip->lowerpath;
+ struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
+ struct inode *inode;
+ struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
+ bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
+ oip->index);
+ int fsid = bylower ? oip->lowerpath->layer->fsid : 0;
+ bool is_dir, metacopy = false;
+ unsigned long ino = 0;
+ int err = -ENOMEM;
+
+ if (!realinode)
+ realinode = d_inode(lowerdentry);
+
+ /*
+ * Copy up origin (lower) may exist for non-indexed upper, but we must
+ * not use lower as hash key if this is a broken hardlink.
+ */
+ is_dir = S_ISDIR(realinode->i_mode);
+ if (upperdentry || bylower) {
+ struct inode *key = d_inode(bylower ? lowerdentry :
+ upperdentry);
+ unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
+
+ inode = ovl_iget5(sb, oip->newinode, key);
+ if (!inode)
+ goto out_err;
+ if (!(inode->i_state & I_NEW)) {
+ /*
+ * Verify that the underlying files stored in the inode
+ * match those in the dentry.
+ */
+ if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
+ true)) {
+ iput(inode);
+ err = -ESTALE;
+ goto out_err;
+ }
+
+ dput(upperdentry);
+ kfree(oip->redirect);
+ goto out;
+ }
+
+ /* Recalculate nlink for non-dir due to indexing */
+ if (!is_dir)
+ nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);
+ set_nlink(inode, nlink);
+ ino = key->i_ino;
+ } else {
+ /* Lower hardlink that will be broken on copy up */
+ inode = new_inode(sb);
+ if (!inode) {
+ err = -ENOMEM;
+ goto out_err;
+ }
+ }
+ ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino, fsid);
+ ovl_inode_init(inode, upperdentry, lowerdentry, oip->lowerdata);
+
+ if (upperdentry && ovl_is_impuredir(upperdentry))
+ ovl_set_flag(OVL_IMPURE, inode);
+
+ if (oip->index)
+ ovl_set_flag(OVL_INDEX, inode);
+
+ if (upperdentry) {
+ err = ovl_check_metacopy_xattr(upperdentry);
+ if (err < 0)
+ goto out_err;
+ metacopy = err;
+ if (!metacopy)
+ ovl_set_flag(OVL_UPPERDATA, inode);
+ }
+
+ OVL_I(inode)->redirect = oip->redirect;
+
+ if (bylower)
+ ovl_set_flag(OVL_CONST_INO, inode);
+
+ /* Check for non-merge dir that may have whiteouts */
+ if (is_dir) {
+ if (((upperdentry && lowerdentry) || oip->numlower > 1) ||
+ ovl_check_origin_xattr(upperdentry ?: lowerdentry)) {
+ ovl_set_flag(OVL_WHITEOUTS, inode);
+ }
+ }
+
+ if (inode->i_state & I_NEW)
+ unlock_new_inode(inode);
+out:
+ return inode;
+
+out_err:
+ inode = ERR_PTR(err);
+ goto out;
+}
diff --git a/fs/overlayfs/namei.c b/fs/overlayfs/namei.c
new file mode 100644
index 0000000..efd3723
--- /dev/null
+++ b/fs/overlayfs/namei.c
@@ -0,0 +1,1156 @@
+/*
+ * Copyright (C) 2011 Novell Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/cred.h>
+#include <linux/ctype.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/ratelimit.h>
+#include <linux/mount.h>
+#include <linux/exportfs.h>
+#include "overlayfs.h"
+
+struct ovl_lookup_data {
+ struct qstr name;
+ bool is_dir;
+ bool opaque;
+ bool stop;
+ bool last;
+ char *redirect;
+ bool metacopy;
+};
+
+static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d,
+ size_t prelen, const char *post)
+{
+ int res;
+ char *buf;
+
+ buf = ovl_get_redirect_xattr(dentry, prelen + strlen(post));
+ if (IS_ERR_OR_NULL(buf))
+ return PTR_ERR(buf);
+
+ if (buf[0] == '/') {
+ /*
+ * One of the ancestor path elements in an absolute path
+ * lookup in ovl_lookup_layer() could have been opaque and
+ * that will stop further lookup in lower layers (d->stop=true)
+ * But we have found an absolute redirect in decendant path
+ * element and that should force continue lookup in lower
+ * layers (reset d->stop).
+ */
+ d->stop = false;
+ } else {
+ res = strlen(buf) + 1;
+ memmove(buf + prelen, buf, res);
+ memcpy(buf, d->name.name, prelen);
+ }
+
+ strcat(buf, post);
+ kfree(d->redirect);
+ d->redirect = buf;
+ d->name.name = d->redirect;
+ d->name.len = strlen(d->redirect);
+
+ return 0;
+}
+
+static int ovl_acceptable(void *ctx, struct dentry *dentry)
+{
+ /*
+ * A non-dir origin may be disconnected, which is fine, because
+ * we only need it for its unique inode number.
+ */
+ if (!d_is_dir(dentry))
+ return 1;
+
+ /* Don't decode a deleted empty directory */
+ if (d_unhashed(dentry))
+ return 0;
+
+ /* Check if directory belongs to the layer we are decoding from */
+ return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root);
+}
+
+/*
+ * Check validity of an overlay file handle buffer.
+ *
+ * Return 0 for a valid file handle.
+ * Return -ENODATA for "origin unknown".
+ * Return <0 for an invalid file handle.
+ */
+int ovl_check_fh_len(struct ovl_fh *fh, int fh_len)
+{
+ if (fh_len < sizeof(struct ovl_fh) || fh_len < fh->len)
+ return -EINVAL;
+
+ if (fh->magic != OVL_FH_MAGIC)
+ return -EINVAL;
+
+ /* Treat larger version and unknown flags as "origin unknown" */
+ if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL)
+ return -ENODATA;
+
+ /* Treat endianness mismatch as "origin unknown" */
+ if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) &&
+ (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN)
+ return -ENODATA;
+
+ return 0;
+}
+
+static struct ovl_fh *ovl_get_fh(struct dentry *dentry, const char *name)
+{
+ int res, err;
+ struct ovl_fh *fh = NULL;
+
+ res = vfs_getxattr(dentry, name, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return NULL;
+ goto fail;
+ }
+ /* Zero size value means "copied up but origin unknown" */
+ if (res == 0)
+ return NULL;
+
+ fh = kzalloc(res, GFP_KERNEL);
+ if (!fh)
+ return ERR_PTR(-ENOMEM);
+
+ res = vfs_getxattr(dentry, name, fh, res);
+ if (res < 0)
+ goto fail;
+
+ err = ovl_check_fh_len(fh, res);
+ if (err < 0) {
+ if (err == -ENODATA)
+ goto out;
+ goto invalid;
+ }
+
+ return fh;
+
+out:
+ kfree(fh);
+ return NULL;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res);
+ goto out;
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh);
+ goto out;
+}
+
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+ bool connected)
+{
+ struct dentry *real;
+ int bytes;
+
+ /*
+ * Make sure that the stored uuid matches the uuid of the lower
+ * layer where file handle will be decoded.
+ */
+ if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid))
+ return NULL;
+
+ bytes = (fh->len - offsetof(struct ovl_fh, fid));
+ real = exportfs_decode_fh(mnt, (struct fid *)fh->fid,
+ bytes >> 2, (int)fh->type,
+ connected ? ovl_acceptable : NULL, mnt);
+ if (IS_ERR(real)) {
+ /*
+ * Treat stale file handle to lower file as "origin unknown".
+ * upper file handle could become stale when upper file is
+ * unlinked and this information is needed to handle stale
+ * index entries correctly.
+ */
+ if (real == ERR_PTR(-ESTALE) &&
+ !(fh->flags & OVL_FH_FLAG_PATH_UPPER))
+ real = NULL;
+ return real;
+ }
+
+ if (ovl_dentry_weird(real)) {
+ dput(real);
+ return NULL;
+ }
+
+ return real;
+}
+
+static bool ovl_is_opaquedir(struct dentry *dentry)
+{
+ return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE);
+}
+
+static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d,
+ const char *name, unsigned int namelen,
+ size_t prelen, const char *post,
+ struct dentry **ret)
+{
+ struct dentry *this;
+ int err;
+ bool last_element = !post[0];
+
+ this = lookup_one_len_unlocked(name, base, namelen);
+ if (IS_ERR(this)) {
+ err = PTR_ERR(this);
+ this = NULL;
+ if (err == -ENOENT || err == -ENAMETOOLONG)
+ goto out;
+ goto out_err;
+ }
+ if (!this->d_inode)
+ goto put_and_out;
+
+ if (ovl_dentry_weird(this)) {
+ /* Don't support traversing automounts and other weirdness */
+ err = -EREMOTE;
+ goto out_err;
+ }
+ if (ovl_is_whiteout(this)) {
+ d->stop = d->opaque = true;
+ goto put_and_out;
+ }
+ /*
+ * This dentry should be a regular file if previous layer lookup
+ * found a metacopy dentry.
+ */
+ if (last_element && d->metacopy && !d_is_reg(this)) {
+ d->stop = true;
+ goto put_and_out;
+ }
+ if (!d_can_lookup(this)) {
+ if (d->is_dir || !last_element) {
+ d->stop = true;
+ goto put_and_out;
+ }
+ err = ovl_check_metacopy_xattr(this);
+ if (err < 0)
+ goto out_err;
+
+ d->metacopy = err;
+ d->stop = !d->metacopy;
+ if (!d->metacopy || d->last)
+ goto out;
+ } else {
+ if (last_element)
+ d->is_dir = true;
+ if (d->last)
+ goto out;
+
+ if (ovl_is_opaquedir(this)) {
+ d->stop = true;
+ if (last_element)
+ d->opaque = true;
+ goto out;
+ }
+ }
+ err = ovl_check_redirect(this, d, prelen, post);
+ if (err)
+ goto out_err;
+out:
+ *ret = this;
+ return 0;
+
+put_and_out:
+ dput(this);
+ this = NULL;
+ goto out;
+
+out_err:
+ dput(this);
+ return err;
+}
+
+static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d,
+ struct dentry **ret)
+{
+ /* Counting down from the end, since the prefix can change */
+ size_t rem = d->name.len - 1;
+ struct dentry *dentry = NULL;
+ int err;
+
+ if (d->name.name[0] != '/')
+ return ovl_lookup_single(base, d, d->name.name, d->name.len,
+ 0, "", ret);
+
+ while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) {
+ const char *s = d->name.name + d->name.len - rem;
+ const char *next = strchrnul(s, '/');
+ size_t thislen = next - s;
+ bool end = !next[0];
+
+ /* Verify we did not go off the rails */
+ if (WARN_ON(s[-1] != '/'))
+ return -EIO;
+
+ err = ovl_lookup_single(base, d, s, thislen,
+ d->name.len - rem, next, &base);
+ dput(dentry);
+ if (err)
+ return err;
+ dentry = base;
+ if (end)
+ break;
+
+ rem -= thislen + 1;
+
+ if (WARN_ON(rem >= d->name.len))
+ return -EIO;
+ }
+ *ret = dentry;
+ return 0;
+}
+
+
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
+ struct dentry *upperdentry, struct ovl_path **stackp)
+{
+ struct dentry *origin = NULL;
+ int i;
+
+ for (i = 0; i < ofs->numlower; i++) {
+ origin = ovl_decode_real_fh(fh, ofs->lower_layers[i].mnt,
+ connected);
+ if (origin)
+ break;
+ }
+
+ if (!origin)
+ return -ESTALE;
+ else if (IS_ERR(origin))
+ return PTR_ERR(origin);
+
+ if (upperdentry && !ovl_is_whiteout(upperdentry) &&
+ ((d_inode(origin)->i_mode ^ d_inode(upperdentry)->i_mode) & S_IFMT))
+ goto invalid;
+
+ if (!*stackp)
+ *stackp = kmalloc(sizeof(struct ovl_path), GFP_KERNEL);
+ if (!*stackp) {
+ dput(origin);
+ return -ENOMEM;
+ }
+ **stackp = (struct ovl_path){
+ .dentry = origin,
+ .layer = &ofs->lower_layers[i]
+ };
+
+ return 0;
+
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid origin (%pd2, ftype=%x, origin ftype=%x).\n",
+ upperdentry, d_inode(upperdentry)->i_mode & S_IFMT,
+ d_inode(origin)->i_mode & S_IFMT);
+ dput(origin);
+ return -EIO;
+}
+
+static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry,
+ struct ovl_path **stackp, unsigned int *ctrp)
+{
+ struct ovl_fh *fh = ovl_get_fh(upperdentry, OVL_XATTR_ORIGIN);
+ int err;
+
+ if (IS_ERR_OR_NULL(fh))
+ return PTR_ERR(fh);
+
+ err = ovl_check_origin_fh(ofs, fh, false, upperdentry, stackp);
+ kfree(fh);
+
+ if (err) {
+ if (err == -ESTALE)
+ return 0;
+ return err;
+ }
+
+ if (WARN_ON(*ctrp))
+ return -EIO;
+
+ *ctrp = 1;
+ return 0;
+}
+
+/*
+ * Verify that @fh matches the file handle stored in xattr @name.
+ * Return 0 on match, -ESTALE on mismatch, < 0 on error.
+ */
+static int ovl_verify_fh(struct dentry *dentry, const char *name,
+ const struct ovl_fh *fh)
+{
+ struct ovl_fh *ofh = ovl_get_fh(dentry, name);
+ int err = 0;
+
+ if (!ofh)
+ return -ENODATA;
+
+ if (IS_ERR(ofh))
+ return PTR_ERR(ofh);
+
+ if (fh->len != ofh->len || memcmp(fh, ofh, fh->len))
+ err = -ESTALE;
+
+ kfree(ofh);
+ return err;
+}
+
+/*
+ * Verify that @real dentry matches the file handle stored in xattr @name.
+ *
+ * If @set is true and there is no stored file handle, encode @real and store
+ * file handle in xattr @name.
+ *
+ * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error.
+ */
+int ovl_verify_set_fh(struct dentry *dentry, const char *name,
+ struct dentry *real, bool is_upper, bool set)
+{
+ struct inode *inode;
+ struct ovl_fh *fh;
+ int err;
+
+ fh = ovl_encode_real_fh(real, is_upper);
+ err = PTR_ERR(fh);
+ if (IS_ERR(fh)) {
+ fh = NULL;
+ goto fail;
+ }
+
+ err = ovl_verify_fh(dentry, name, fh);
+ if (set && err == -ENODATA)
+ err = ovl_do_setxattr(dentry, name, fh, fh->len, 0);
+ if (err)
+ goto fail;
+
+out:
+ kfree(fh);
+ return err;
+
+fail:
+ inode = d_inode(real);
+ pr_warn_ratelimited("overlayfs: failed to verify %s (%pd2, ino=%lu, err=%i)\n",
+ is_upper ? "upper" : "origin", real,
+ inode ? inode->i_ino : 0, err);
+ goto out;
+}
+
+/* Get upper dentry from index */
+struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index)
+{
+ struct ovl_fh *fh;
+ struct dentry *upper;
+
+ if (!d_is_dir(index))
+ return dget(index);
+
+ fh = ovl_get_fh(index, OVL_XATTR_UPPER);
+ if (IS_ERR_OR_NULL(fh))
+ return ERR_CAST(fh);
+
+ upper = ovl_decode_real_fh(fh, ofs->upper_mnt, true);
+ kfree(fh);
+
+ if (IS_ERR_OR_NULL(upper))
+ return upper ?: ERR_PTR(-ESTALE);
+
+ if (!d_is_dir(upper)) {
+ pr_warn_ratelimited("overlayfs: invalid index upper (%pd2, upper=%pd2).\n",
+ index, upper);
+ dput(upper);
+ return ERR_PTR(-EIO);
+ }
+
+ return upper;
+}
+
+/* Is this a leftover from create/whiteout of directory index entry? */
+static bool ovl_is_temp_index(struct dentry *index)
+{
+ return index->d_name.name[0] == '#';
+}
+
+/*
+ * Verify that an index entry name matches the origin file handle stored in
+ * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path.
+ * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error.
+ */
+int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index)
+{
+ struct ovl_fh *fh = NULL;
+ size_t len;
+ struct ovl_path origin = { };
+ struct ovl_path *stack = &origin;
+ struct dentry *upper = NULL;
+ int err;
+
+ if (!d_inode(index))
+ return 0;
+
+ /* Cleanup leftover from index create/cleanup attempt */
+ err = -ESTALE;
+ if (ovl_is_temp_index(index))
+ goto fail;
+
+ err = -EINVAL;
+ if (index->d_name.len < sizeof(struct ovl_fh)*2)
+ goto fail;
+
+ err = -ENOMEM;
+ len = index->d_name.len / 2;
+ fh = kzalloc(len, GFP_KERNEL);
+ if (!fh)
+ goto fail;
+
+ err = -EINVAL;
+ if (hex2bin((u8 *)fh, index->d_name.name, len))
+ goto fail;
+
+ err = ovl_check_fh_len(fh, len);
+ if (err)
+ goto fail;
+
+ /*
+ * Whiteout index entries are used as an indication that an exported
+ * overlay file handle should be treated as stale (i.e. after unlink
+ * of the overlay inode). These entries contain no origin xattr.
+ */
+ if (ovl_is_whiteout(index))
+ goto out;
+
+ /*
+ * Verifying directory index entries are not stale is expensive, so
+ * only verify stale dir index if NFS export is enabled.
+ */
+ if (d_is_dir(index) && !ofs->config.nfs_export)
+ goto out;
+
+ /*
+ * Directory index entries should have 'upper' xattr pointing to the
+ * real upper dir. Non-dir index entries are hardlinks to the upper
+ * real inode. For non-dir index, we can read the copy up origin xattr
+ * directly from the index dentry, but for dir index we first need to
+ * decode the upper directory.
+ */
+ upper = ovl_index_upper(ofs, index);
+ if (IS_ERR_OR_NULL(upper)) {
+ err = PTR_ERR(upper);
+ /*
+ * Directory index entries with no 'upper' xattr need to be
+ * removed. When dir index entry has a stale 'upper' xattr,
+ * we assume that upper dir was removed and we treat the dir
+ * index as orphan entry that needs to be whited out.
+ */
+ if (err == -ESTALE)
+ goto orphan;
+ else if (!err)
+ err = -ESTALE;
+ goto fail;
+ }
+
+ err = ovl_verify_fh(upper, OVL_XATTR_ORIGIN, fh);
+ dput(upper);
+ if (err)
+ goto fail;
+
+ /* Check if non-dir index is orphan and don't warn before cleaning it */
+ if (!d_is_dir(index) && d_inode(index)->i_nlink == 1) {
+ err = ovl_check_origin_fh(ofs, fh, false, index, &stack);
+ if (err)
+ goto fail;
+
+ if (ovl_get_nlink(origin.dentry, index, 0) == 0)
+ goto orphan;
+ }
+
+out:
+ dput(origin.dentry);
+ kfree(fh);
+ return err;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to verify index (%pd2, ftype=%x, err=%i)\n",
+ index, d_inode(index)->i_mode & S_IFMT, err);
+ goto out;
+
+orphan:
+ pr_warn_ratelimited("overlayfs: orphan index entry (%pd2, ftype=%x, nlink=%u)\n",
+ index, d_inode(index)->i_mode & S_IFMT,
+ d_inode(index)->i_nlink);
+ err = -ENOENT;
+ goto out;
+}
+
+static int ovl_get_index_name_fh(struct ovl_fh *fh, struct qstr *name)
+{
+ char *n, *s;
+
+ n = kcalloc(fh->len, 2, GFP_KERNEL);
+ if (!n)
+ return -ENOMEM;
+
+ s = bin2hex(n, fh, fh->len);
+ *name = (struct qstr) QSTR_INIT(n, s - n);
+
+ return 0;
+
+}
+
+/*
+ * Lookup in indexdir for the index entry of a lower real inode or a copy up
+ * origin inode. The index entry name is the hex representation of the lower
+ * inode file handle.
+ *
+ * If the index dentry in negative, then either no lower aliases have been
+ * copied up yet, or aliases have been copied up in older kernels and are
+ * not indexed.
+ *
+ * If the index dentry for a copy up origin inode is positive, but points
+ * to an inode different than the upper inode, then either the upper inode
+ * has been copied up and not indexed or it was indexed, but since then
+ * index dir was cleared. Either way, that index cannot be used to indentify
+ * the overlay inode.
+ */
+int ovl_get_index_name(struct dentry *origin, struct qstr *name)
+{
+ struct ovl_fh *fh;
+ int err;
+
+ fh = ovl_encode_real_fh(origin, false);
+ if (IS_ERR(fh))
+ return PTR_ERR(fh);
+
+ err = ovl_get_index_name_fh(fh, name);
+
+ kfree(fh);
+ return err;
+}
+
+/* Lookup index by file handle for NFS export */
+struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh)
+{
+ struct dentry *index;
+ struct qstr name;
+ int err;
+
+ err = ovl_get_index_name_fh(fh, &name);
+ if (err)
+ return ERR_PTR(err);
+
+ index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ kfree(name.name);
+ if (IS_ERR(index)) {
+ if (PTR_ERR(index) == -ENOENT)
+ index = NULL;
+ return index;
+ }
+
+ if (d_is_negative(index))
+ err = 0;
+ else if (ovl_is_whiteout(index))
+ err = -ESTALE;
+ else if (ovl_dentry_weird(index))
+ err = -EIO;
+ else
+ return index;
+
+ dput(index);
+ return ERR_PTR(err);
+}
+
+struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
+ struct dentry *origin, bool verify)
+{
+ struct dentry *index;
+ struct inode *inode;
+ struct qstr name;
+ bool is_dir = d_is_dir(origin);
+ int err;
+
+ err = ovl_get_index_name(origin, &name);
+ if (err)
+ return ERR_PTR(err);
+
+ index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ if (err == -ENOENT) {
+ index = NULL;
+ goto out;
+ }
+ pr_warn_ratelimited("overlayfs: failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n"
+ "overlayfs: mount with '-o index=off' to disable inodes index.\n",
+ d_inode(origin)->i_ino, name.len, name.name,
+ err);
+ goto out;
+ }
+
+ inode = d_inode(index);
+ if (d_is_negative(index)) {
+ goto out_dput;
+ } else if (ovl_is_whiteout(index) && !verify) {
+ /*
+ * When index lookup is called with !verify for decoding an
+ * overlay file handle, a whiteout index implies that decode
+ * should treat file handle as stale and no need to print a
+ * warning about it.
+ */
+ dput(index);
+ index = ERR_PTR(-ESTALE);
+ goto out;
+ } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) ||
+ ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) {
+ /*
+ * Index should always be of the same file type as origin
+ * except for the case of a whiteout index. A whiteout
+ * index should only exist if all lower aliases have been
+ * unlinked, which means that finding a lower origin on lookup
+ * whose index is a whiteout should be treated as an error.
+ */
+ pr_warn_ratelimited("overlayfs: bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n",
+ index, d_inode(index)->i_mode & S_IFMT,
+ d_inode(origin)->i_mode & S_IFMT);
+ goto fail;
+ } else if (is_dir && verify) {
+ if (!upper) {
+ pr_warn_ratelimited("overlayfs: suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n",
+ origin, index);
+ goto fail;
+ }
+
+ /* Verify that dir index 'upper' xattr points to upper dir */
+ err = ovl_verify_upper(index, upper, false);
+ if (err) {
+ if (err == -ESTALE) {
+ pr_warn_ratelimited("overlayfs: suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n",
+ upper, origin, index);
+ }
+ goto fail;
+ }
+ } else if (upper && d_inode(upper) != inode) {
+ goto out_dput;
+ }
+out:
+ kfree(name.name);
+ return index;
+
+out_dput:
+ dput(index);
+ index = NULL;
+ goto out;
+
+fail:
+ dput(index);
+ index = ERR_PTR(-EIO);
+ goto out;
+}
+
+/*
+ * Returns next layer in stack starting from top.
+ * Returns -1 if this is the last layer.
+ */
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ BUG_ON(idx < 0);
+ if (idx == 0) {
+ ovl_path_upper(dentry, path);
+ if (path->dentry)
+ return oe->numlower ? 1 : -1;
+ idx++;
+ }
+ BUG_ON(idx > oe->numlower);
+ path->dentry = oe->lowerstack[idx - 1].dentry;
+ path->mnt = oe->lowerstack[idx - 1].layer->mnt;
+
+ return (idx < oe->numlower) ? idx + 1 : -1;
+}
+
+/* Fix missing 'origin' xattr */
+static int ovl_fix_origin(struct dentry *dentry, struct dentry *lower,
+ struct dentry *upper)
+{
+ int err;
+
+ if (ovl_check_origin_xattr(upper))
+ return 0;
+
+ err = ovl_want_write(dentry);
+ if (err)
+ return err;
+
+ err = ovl_set_origin(dentry, lower, upper);
+ if (!err)
+ err = ovl_set_impure(dentry->d_parent, upper->d_parent);
+
+ ovl_drop_write(dentry);
+ return err;
+}
+
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags)
+{
+ struct ovl_entry *oe;
+ const struct cred *old_cred;
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+ struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata;
+ struct ovl_path *stack = NULL, *origin_path = NULL;
+ struct dentry *upperdir, *upperdentry = NULL;
+ struct dentry *origin = NULL;
+ struct dentry *index = NULL;
+ unsigned int ctr = 0;
+ struct inode *inode = NULL;
+ bool upperopaque = false;
+ char *upperredirect = NULL;
+ struct dentry *this;
+ unsigned int i;
+ int err;
+ bool metacopy = false;
+ struct ovl_lookup_data d = {
+ .name = dentry->d_name,
+ .is_dir = false,
+ .opaque = false,
+ .stop = false,
+ .last = ofs->config.redirect_follow ? false : !poe->numlower,
+ .redirect = NULL,
+ .metacopy = false,
+ };
+
+ if (dentry->d_name.len > ofs->namelen)
+ return ERR_PTR(-ENAMETOOLONG);
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ upperdir = ovl_dentry_upper(dentry->d_parent);
+ if (upperdir) {
+ err = ovl_lookup_layer(upperdir, &d, &upperdentry);
+ if (err)
+ goto out;
+
+ if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) {
+ dput(upperdentry);
+ err = -EREMOTE;
+ goto out;
+ }
+ if (upperdentry && !d.is_dir) {
+ unsigned int origin_ctr = 0;
+
+ /*
+ * Lookup copy up origin by decoding origin file handle.
+ * We may get a disconnected dentry, which is fine,
+ * because we only need to hold the origin inode in
+ * cache and use its inode number. We may even get a
+ * connected dentry, that is not under any of the lower
+ * layers root. That is also fine for using it's inode
+ * number - it's the same as if we held a reference
+ * to a dentry in lower layer that was moved under us.
+ */
+ err = ovl_check_origin(ofs, upperdentry, &origin_path,
+ &origin_ctr);
+ if (err)
+ goto out_put_upper;
+
+ if (d.metacopy)
+ metacopy = true;
+ }
+
+ if (d.redirect) {
+ err = -ENOMEM;
+ upperredirect = kstrdup(d.redirect, GFP_KERNEL);
+ if (!upperredirect)
+ goto out_put_upper;
+ if (d.redirect[0] == '/')
+ poe = roe;
+ }
+ upperopaque = d.opaque;
+ }
+
+ if (!d.stop && poe->numlower) {
+ err = -ENOMEM;
+ stack = kcalloc(ofs->numlower, sizeof(struct ovl_path),
+ GFP_KERNEL);
+ if (!stack)
+ goto out_put_upper;
+ }
+
+ for (i = 0; !d.stop && i < poe->numlower; i++) {
+ struct ovl_path lower = poe->lowerstack[i];
+
+ if (!ofs->config.redirect_follow)
+ d.last = i == poe->numlower - 1;
+ else
+ d.last = lower.layer->idx == roe->numlower;
+
+ err = ovl_lookup_layer(lower.dentry, &d, &this);
+ if (err)
+ goto out_put;
+
+ if (!this)
+ continue;
+
+ /*
+ * If no origin fh is stored in upper of a merge dir, store fh
+ * of lower dir and set upper parent "impure".
+ */
+ if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) {
+ err = ovl_fix_origin(dentry, this, upperdentry);
+ if (err) {
+ dput(this);
+ goto out_put;
+ }
+ }
+
+ /*
+ * When "verify_lower" feature is enabled, do not merge with a
+ * lower dir that does not match a stored origin xattr. In any
+ * case, only verified origin is used for index lookup.
+ *
+ * For non-dir dentry, if index=on, then ensure origin
+ * matches the dentry found using path based lookup,
+ * otherwise error out.
+ */
+ if (upperdentry && !ctr &&
+ ((d.is_dir && ovl_verify_lower(dentry->d_sb)) ||
+ (!d.is_dir && ofs->config.index && origin_path))) {
+ err = ovl_verify_origin(upperdentry, this, false);
+ if (err) {
+ dput(this);
+ if (d.is_dir)
+ break;
+ goto out_put;
+ }
+ origin = this;
+ }
+
+ if (d.metacopy)
+ metacopy = true;
+ /*
+ * Do not store intermediate metacopy dentries in chain,
+ * except top most lower metacopy dentry
+ */
+ if (d.metacopy && ctr) {
+ dput(this);
+ continue;
+ }
+
+ stack[ctr].dentry = this;
+ stack[ctr].layer = lower.layer;
+ ctr++;
+
+ /*
+ * Following redirects can have security consequences: it's like
+ * a symlink into the lower layer without the permission checks.
+ * This is only a problem if the upper layer is untrusted (e.g
+ * comes from an USB drive). This can allow a non-readable file
+ * or directory to become readable.
+ *
+ * Only following redirects when redirects are enabled disables
+ * this attack vector when not necessary.
+ */
+ err = -EPERM;
+ if (d.redirect && !ofs->config.redirect_follow) {
+ pr_warn_ratelimited("overlayfs: refusing to follow redirect for (%pd2)\n",
+ dentry);
+ goto out_put;
+ }
+
+ if (d.stop)
+ break;
+
+ if (d.redirect && d.redirect[0] == '/' && poe != roe) {
+ poe = roe;
+ /* Find the current layer on the root dentry */
+ i = lower.layer->idx - 1;
+ }
+ }
+
+ if (metacopy) {
+ /*
+ * Found a metacopy dentry but did not find corresponding
+ * data dentry
+ */
+ if (d.metacopy) {
+ err = -EIO;
+ goto out_put;
+ }
+
+ err = -EPERM;
+ if (!ofs->config.metacopy) {
+ pr_warn_ratelimited("overlay: refusing to follow metacopy origin for (%pd2)\n",
+ dentry);
+ goto out_put;
+ }
+ } else if (!d.is_dir && upperdentry && !ctr && origin_path) {
+ if (WARN_ON(stack != NULL)) {
+ err = -EIO;
+ goto out_put;
+ }
+ stack = origin_path;
+ ctr = 1;
+ origin_path = NULL;
+ }
+
+ /*
+ * Lookup index by lower inode and verify it matches upper inode.
+ * We only trust dir index if we verified that lower dir matches
+ * origin, otherwise dir index entries may be inconsistent and we
+ * ignore them.
+ *
+ * For non-dir upper metacopy dentry, we already set "origin" if we
+ * verified that lower matched upper origin. If upper origin was
+ * not present (because lower layer did not support fh encode/decode),
+ * or indexing is not enabled, do not set "origin" and skip looking up
+ * index. This case should be handled in same way as a non-dir upper
+ * without ORIGIN is handled.
+ *
+ * Always lookup index of non-dir non-metacopy and non-upper.
+ */
+ if (ctr && (!upperdentry || (!d.is_dir && !metacopy)))
+ origin = stack[0].dentry;
+
+ if (origin && ovl_indexdir(dentry->d_sb) &&
+ (!d.is_dir || ovl_index_all(dentry->d_sb))) {
+ index = ovl_lookup_index(ofs, upperdentry, origin, true);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ index = NULL;
+ goto out_put;
+ }
+ }
+
+ oe = ovl_alloc_entry(ctr);
+ err = -ENOMEM;
+ if (!oe)
+ goto out_put;
+
+ memcpy(oe->lowerstack, stack, sizeof(struct ovl_path) * ctr);
+ dentry->d_fsdata = oe;
+
+ if (upperopaque)
+ ovl_dentry_set_opaque(dentry);
+
+ if (upperdentry)
+ ovl_dentry_set_upper_alias(dentry);
+ else if (index) {
+ upperdentry = dget(index);
+ upperredirect = ovl_get_redirect_xattr(upperdentry, 0);
+ if (IS_ERR(upperredirect)) {
+ err = PTR_ERR(upperredirect);
+ upperredirect = NULL;
+ goto out_free_oe;
+ }
+ }
+
+ if (upperdentry || ctr) {
+ struct ovl_inode_params oip = {
+ .upperdentry = upperdentry,
+ .lowerpath = stack,
+ .index = index,
+ .numlower = ctr,
+ .redirect = upperredirect,
+ .lowerdata = (ctr > 1 && !d.is_dir) ?
+ stack[ctr - 1].dentry : NULL,
+ };
+
+ inode = ovl_get_inode(dentry->d_sb, &oip);
+ err = PTR_ERR(inode);
+ if (IS_ERR(inode))
+ goto out_free_oe;
+ }
+
+ revert_creds(old_cred);
+ if (origin_path) {
+ dput(origin_path->dentry);
+ kfree(origin_path);
+ }
+ dput(index);
+ kfree(stack);
+ kfree(d.redirect);
+ return d_splice_alias(inode, dentry);
+
+out_free_oe:
+ dentry->d_fsdata = NULL;
+ kfree(oe);
+out_put:
+ dput(index);
+ for (i = 0; i < ctr; i++)
+ dput(stack[i].dentry);
+ kfree(stack);
+out_put_upper:
+ if (origin_path) {
+ dput(origin_path->dentry);
+ kfree(origin_path);
+ }
+ dput(upperdentry);
+ kfree(upperredirect);
+out:
+ kfree(d.redirect);
+ revert_creds(old_cred);
+ return ERR_PTR(err);
+}
+
+bool ovl_lower_positive(struct dentry *dentry)
+{
+ struct ovl_entry *poe = dentry->d_parent->d_fsdata;
+ const struct qstr *name = &dentry->d_name;
+ const struct cred *old_cred;
+ unsigned int i;
+ bool positive = false;
+ bool done = false;
+
+ /*
+ * If dentry is negative, then lower is positive iff this is a
+ * whiteout.
+ */
+ if (!dentry->d_inode)
+ return ovl_dentry_is_opaque(dentry);
+
+ /* Negative upper -> positive lower */
+ if (!ovl_dentry_upper(dentry))
+ return true;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ /* Positive upper -> have to look up lower to see whether it exists */
+ for (i = 0; !done && !positive && i < poe->numlower; i++) {
+ struct dentry *this;
+ struct dentry *lowerdir = poe->lowerstack[i].dentry;
+
+ this = lookup_one_len_unlocked(name->name, lowerdir,
+ name->len);
+ if (IS_ERR(this)) {
+ switch (PTR_ERR(this)) {
+ case -ENOENT:
+ case -ENAMETOOLONG:
+ break;
+
+ default:
+ /*
+ * Assume something is there, we just couldn't
+ * access it.
+ */
+ positive = true;
+ break;
+ }
+ } else {
+ if (this->d_inode) {
+ positive = !ovl_is_whiteout(this);
+ done = true;
+ }
+ dput(this);
+ }
+ }
+ revert_creds(old_cred);
+
+ return positive;
+}
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
new file mode 100644
index 0000000..a3c0d95
--- /dev/null
+++ b/fs/overlayfs/overlayfs.h
@@ -0,0 +1,420 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/uuid.h>
+#include <linux/fs.h>
+#include "ovl_entry.h"
+
+enum ovl_path_type {
+ __OVL_PATH_UPPER = (1 << 0),
+ __OVL_PATH_MERGE = (1 << 1),
+ __OVL_PATH_ORIGIN = (1 << 2),
+};
+
+#define OVL_TYPE_UPPER(type) ((type) & __OVL_PATH_UPPER)
+#define OVL_TYPE_MERGE(type) ((type) & __OVL_PATH_MERGE)
+#define OVL_TYPE_ORIGIN(type) ((type) & __OVL_PATH_ORIGIN)
+
+#define OVL_XATTR_PREFIX XATTR_TRUSTED_PREFIX "overlay."
+#define OVL_XATTR_OPAQUE OVL_XATTR_PREFIX "opaque"
+#define OVL_XATTR_REDIRECT OVL_XATTR_PREFIX "redirect"
+#define OVL_XATTR_ORIGIN OVL_XATTR_PREFIX "origin"
+#define OVL_XATTR_IMPURE OVL_XATTR_PREFIX "impure"
+#define OVL_XATTR_NLINK OVL_XATTR_PREFIX "nlink"
+#define OVL_XATTR_UPPER OVL_XATTR_PREFIX "upper"
+#define OVL_XATTR_METACOPY OVL_XATTR_PREFIX "metacopy"
+
+enum ovl_inode_flag {
+ /* Pure upper dir that may contain non pure upper entries */
+ OVL_IMPURE,
+ /* Non-merge dir that may contain whiteout entries */
+ OVL_WHITEOUTS,
+ OVL_INDEX,
+ OVL_UPPERDATA,
+ /* Inode number will remain constant over copy up. */
+ OVL_CONST_INO,
+};
+
+enum ovl_entry_flag {
+ OVL_E_UPPER_ALIAS,
+ OVL_E_OPAQUE,
+ OVL_E_CONNECTED,
+};
+
+/*
+ * The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
+ * where:
+ * origin.fh - exported file handle of the lower file
+ * origin.uuid - uuid of the lower filesystem
+ */
+#define OVL_FH_VERSION 0
+#define OVL_FH_MAGIC 0xfb
+
+/* CPU byte order required for fid decoding: */
+#define OVL_FH_FLAG_BIG_ENDIAN (1 << 0)
+#define OVL_FH_FLAG_ANY_ENDIAN (1 << 1)
+/* Is the real inode encoded in fid an upper inode? */
+#define OVL_FH_FLAG_PATH_UPPER (1 << 2)
+
+#define OVL_FH_FLAG_ALL (OVL_FH_FLAG_BIG_ENDIAN | OVL_FH_FLAG_ANY_ENDIAN | \
+ OVL_FH_FLAG_PATH_UPPER)
+
+#if defined(__LITTLE_ENDIAN)
+#define OVL_FH_FLAG_CPU_ENDIAN 0
+#elif defined(__BIG_ENDIAN)
+#define OVL_FH_FLAG_CPU_ENDIAN OVL_FH_FLAG_BIG_ENDIAN
+#else
+#error Endianness not defined
+#endif
+
+/* The type returned by overlay exportfs ops when encoding an ovl_fh handle */
+#define OVL_FILEID 0xfb
+
+/* On-disk and in-memeory format for redirect by file handle */
+struct ovl_fh {
+ u8 version; /* 0 */
+ u8 magic; /* 0xfb */
+ u8 len; /* size of this header + size of fid */
+ u8 flags; /* OVL_FH_FLAG_* */
+ u8 type; /* fid_type of fid */
+ uuid_t uuid; /* uuid of filesystem */
+ u8 fid[0]; /* file identifier */
+} __packed;
+
+static inline int ovl_do_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_rmdir(dir, dentry);
+
+ pr_debug("rmdir(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+static inline int ovl_do_unlink(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_unlink(dir, dentry, NULL);
+
+ pr_debug("unlink(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+static inline int ovl_do_link(struct dentry *old_dentry, struct inode *dir,
+ struct dentry *new_dentry)
+{
+ int err = vfs_link(old_dentry, dir, new_dentry, NULL);
+
+ pr_debug("link(%pd2, %pd2) = %i\n", old_dentry, new_dentry, err);
+ return err;
+}
+
+static inline int ovl_do_create(struct inode *dir, struct dentry *dentry,
+ umode_t mode)
+{
+ int err = vfs_create(dir, dentry, mode, true);
+
+ pr_debug("create(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return err;
+}
+
+static inline int ovl_do_mkdir(struct inode *dir, struct dentry *dentry,
+ umode_t mode)
+{
+ int err = vfs_mkdir(dir, dentry, mode);
+ pr_debug("mkdir(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return err;
+}
+
+static inline int ovl_do_mknod(struct inode *dir, struct dentry *dentry,
+ umode_t mode, dev_t dev)
+{
+ int err = vfs_mknod(dir, dentry, mode, dev);
+
+ pr_debug("mknod(%pd2, 0%o, 0%o) = %i\n", dentry, mode, dev, err);
+ return err;
+}
+
+static inline int ovl_do_symlink(struct inode *dir, struct dentry *dentry,
+ const char *oldname)
+{
+ int err = vfs_symlink(dir, dentry, oldname);
+
+ pr_debug("symlink(\"%s\", %pd2) = %i\n", oldname, dentry, err);
+ return err;
+}
+
+static inline int ovl_do_setxattr(struct dentry *dentry, const char *name,
+ const void *value, size_t size, int flags)
+{
+ int err = vfs_setxattr(dentry, name, value, size, flags);
+ pr_debug("setxattr(%pd2, \"%s\", \"%*pE\", %zu, 0x%x) = %i\n",
+ dentry, name, min((int)size, 48), value, size, flags, err);
+ return err;
+}
+
+static inline int ovl_do_removexattr(struct dentry *dentry, const char *name)
+{
+ int err = vfs_removexattr(dentry, name);
+ pr_debug("removexattr(%pd2, \"%s\") = %i\n", dentry, name, err);
+ return err;
+}
+
+static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
+ struct inode *newdir, struct dentry *newdentry,
+ unsigned int flags)
+{
+ int err;
+
+ pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
+ err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
+ if (err) {
+ pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
+ olddentry, newdentry, err);
+ }
+ return err;
+}
+
+static inline int ovl_do_whiteout(struct inode *dir, struct dentry *dentry)
+{
+ int err = vfs_whiteout(dir, dentry);
+ pr_debug("whiteout(%pd2) = %i\n", dentry, err);
+ return err;
+}
+
+static inline struct dentry *ovl_do_tmpfile(struct dentry *dentry, umode_t mode)
+{
+ struct dentry *ret = vfs_tmpfile(dentry, mode, 0);
+ int err = PTR_ERR_OR_ZERO(ret);
+
+ pr_debug("tmpfile(%pd2, 0%o) = %i\n", dentry, mode, err);
+ return ret;
+}
+
+static inline bool ovl_open_flags_need_copy_up(int flags)
+{
+ if (!flags)
+ return false;
+
+ return ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC));
+}
+
+/* util.c */
+int ovl_want_write(struct dentry *dentry);
+void ovl_drop_write(struct dentry *dentry);
+struct dentry *ovl_workdir(struct dentry *dentry);
+const struct cred *ovl_override_creds(struct super_block *sb);
+struct super_block *ovl_same_sb(struct super_block *sb);
+int ovl_can_decode_fh(struct super_block *sb);
+struct dentry *ovl_indexdir(struct super_block *sb);
+bool ovl_index_all(struct super_block *sb);
+bool ovl_verify_lower(struct super_block *sb);
+struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
+bool ovl_dentry_remote(struct dentry *dentry);
+bool ovl_dentry_weird(struct dentry *dentry);
+enum ovl_path_type ovl_path_type(struct dentry *dentry);
+void ovl_path_upper(struct dentry *dentry, struct path *path);
+void ovl_path_lower(struct dentry *dentry, struct path *path);
+void ovl_path_lowerdata(struct dentry *dentry, struct path *path);
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path);
+struct dentry *ovl_dentry_upper(struct dentry *dentry);
+struct dentry *ovl_dentry_lower(struct dentry *dentry);
+struct dentry *ovl_dentry_lowerdata(struct dentry *dentry);
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry);
+struct dentry *ovl_dentry_real(struct dentry *dentry);
+struct dentry *ovl_i_dentry_upper(struct inode *inode);
+struct inode *ovl_inode_upper(struct inode *inode);
+struct inode *ovl_inode_lower(struct inode *inode);
+struct inode *ovl_inode_lowerdata(struct inode *inode);
+struct inode *ovl_inode_real(struct inode *inode);
+struct inode *ovl_inode_realdata(struct inode *inode);
+struct ovl_dir_cache *ovl_dir_cache(struct inode *inode);
+void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache);
+void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry);
+void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry);
+bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry);
+bool ovl_dentry_is_opaque(struct dentry *dentry);
+bool ovl_dentry_is_whiteout(struct dentry *dentry);
+void ovl_dentry_set_opaque(struct dentry *dentry);
+bool ovl_dentry_has_upper_alias(struct dentry *dentry);
+void ovl_dentry_set_upper_alias(struct dentry *dentry);
+bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags);
+bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags);
+bool ovl_has_upperdata(struct inode *inode);
+void ovl_set_upperdata(struct inode *inode);
+bool ovl_redirect_dir(struct super_block *sb);
+const char *ovl_dentry_get_redirect(struct dentry *dentry);
+void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect);
+void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
+ struct dentry *lowerdentry, struct dentry *lowerdata);
+void ovl_inode_update(struct inode *inode, struct dentry *upperdentry);
+void ovl_dir_modified(struct dentry *dentry, bool impurity);
+u64 ovl_dentry_version_get(struct dentry *dentry);
+bool ovl_is_whiteout(struct dentry *dentry);
+struct file *ovl_path_open(struct path *path, int flags);
+int ovl_copy_up_start(struct dentry *dentry, int flags);
+void ovl_copy_up_end(struct dentry *dentry);
+bool ovl_already_copied_up(struct dentry *dentry, int flags);
+bool ovl_check_origin_xattr(struct dentry *dentry);
+bool ovl_check_dir_xattr(struct dentry *dentry, const char *name);
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+ const char *name, const void *value, size_t size,
+ int xerr);
+int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry);
+void ovl_set_flag(unsigned long flag, struct inode *inode);
+void ovl_clear_flag(unsigned long flag, struct inode *inode);
+bool ovl_test_flag(unsigned long flag, struct inode *inode);
+bool ovl_inuse_trylock(struct dentry *dentry);
+void ovl_inuse_unlock(struct dentry *dentry);
+bool ovl_need_index(struct dentry *dentry);
+int ovl_nlink_start(struct dentry *dentry, bool *locked);
+void ovl_nlink_end(struct dentry *dentry, bool locked);
+int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
+int ovl_check_metacopy_xattr(struct dentry *dentry);
+bool ovl_is_metacopy_dentry(struct dentry *dentry);
+char *ovl_get_redirect_xattr(struct dentry *dentry, int padding);
+
+static inline bool ovl_is_impuredir(struct dentry *dentry)
+{
+ return ovl_check_dir_xattr(dentry, OVL_XATTR_IMPURE);
+}
+
+static inline unsigned int ovl_xino_bits(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->xino_bits;
+}
+
+
+/* namei.c */
+int ovl_check_fh_len(struct ovl_fh *fh, int fh_len);
+struct dentry *ovl_decode_real_fh(struct ovl_fh *fh, struct vfsmount *mnt,
+ bool connected);
+int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected,
+ struct dentry *upperdentry, struct ovl_path **stackp);
+int ovl_verify_set_fh(struct dentry *dentry, const char *name,
+ struct dentry *real, bool is_upper, bool set);
+struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index);
+int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index);
+int ovl_get_index_name(struct dentry *origin, struct qstr *name);
+struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh);
+struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper,
+ struct dentry *origin, bool verify);
+int ovl_path_next(int idx, struct dentry *dentry, struct path *path);
+struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry,
+ unsigned int flags);
+bool ovl_lower_positive(struct dentry *dentry);
+
+static inline int ovl_verify_origin(struct dentry *upper,
+ struct dentry *origin, bool set)
+{
+ return ovl_verify_set_fh(upper, OVL_XATTR_ORIGIN, origin, false, set);
+}
+
+static inline int ovl_verify_upper(struct dentry *index,
+ struct dentry *upper, bool set)
+{
+ return ovl_verify_set_fh(index, OVL_XATTR_UPPER, upper, true, set);
+}
+
+/* readdir.c */
+extern const struct file_operations ovl_dir_operations;
+int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list);
+void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list);
+void ovl_cache_free(struct list_head *list);
+void ovl_dir_cache_free(struct inode *inode);
+int ovl_check_d_type_supported(struct path *realpath);
+void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
+ struct dentry *dentry, int level);
+int ovl_indexdir_cleanup(struct ovl_fs *ofs);
+
+/* inode.c */
+int ovl_set_nlink_upper(struct dentry *dentry);
+int ovl_set_nlink_lower(struct dentry *dentry);
+unsigned int ovl_get_nlink(struct dentry *lowerdentry,
+ struct dentry *upperdentry,
+ unsigned int fallback);
+int ovl_setattr(struct dentry *dentry, struct iattr *attr);
+int ovl_getattr(const struct path *path, struct kstat *stat,
+ u32 request_mask, unsigned int flags);
+int ovl_permission(struct inode *inode, int mask);
+int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name,
+ const void *value, size_t size, int flags);
+int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name,
+ void *value, size_t size);
+ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size);
+struct posix_acl *ovl_get_acl(struct inode *inode, int type);
+int ovl_update_time(struct inode *inode, struct timespec64 *ts, int flags);
+bool ovl_is_private_xattr(const char *name);
+
+struct ovl_inode_params {
+ struct inode *newinode;
+ struct dentry *upperdentry;
+ struct ovl_path *lowerpath;
+ struct dentry *index;
+ unsigned int numlower;
+ char *redirect;
+ struct dentry *lowerdata;
+};
+struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev);
+struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
+ bool is_upper);
+struct inode *ovl_get_inode(struct super_block *sb,
+ struct ovl_inode_params *oip);
+static inline void ovl_copyattr(struct inode *from, struct inode *to)
+{
+ to->i_uid = from->i_uid;
+ to->i_gid = from->i_gid;
+ to->i_mode = from->i_mode;
+ to->i_atime = from->i_atime;
+ to->i_mtime = from->i_mtime;
+ to->i_ctime = from->i_ctime;
+ i_size_write(to, i_size_read(from));
+}
+
+static inline void ovl_copyflags(struct inode *from, struct inode *to)
+{
+ unsigned int mask = S_SYNC | S_IMMUTABLE | S_APPEND | S_NOATIME;
+
+ inode_set_flags(to, from->i_flags & mask, mask);
+}
+
+/* dir.c */
+extern const struct inode_operations ovl_dir_inode_operations;
+int ovl_cleanup_and_whiteout(struct dentry *workdir, struct inode *dir,
+ struct dentry *dentry);
+struct ovl_cattr {
+ dev_t rdev;
+ umode_t mode;
+ const char *link;
+ struct dentry *hardlink;
+};
+
+#define OVL_CATTR(m) (&(struct ovl_cattr) { .mode = (m) })
+
+struct dentry *ovl_create_real(struct inode *dir, struct dentry *newdentry,
+ struct ovl_cattr *attr);
+int ovl_cleanup(struct inode *dir, struct dentry *dentry);
+struct dentry *ovl_create_temp(struct dentry *workdir, struct ovl_cattr *attr);
+
+/* file.c */
+extern const struct file_operations ovl_file_operations;
+
+/* copy_up.c */
+int ovl_copy_up(struct dentry *dentry);
+int ovl_copy_up_with_data(struct dentry *dentry);
+int ovl_copy_up_flags(struct dentry *dentry, int flags);
+int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags);
+int ovl_copy_xattr(struct dentry *old, struct dentry *new);
+int ovl_set_attr(struct dentry *upper, struct kstat *stat);
+struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper);
+int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
+ struct dentry *upper);
+
+/* export.c */
+extern const struct export_operations ovl_export_operations;
diff --git a/fs/overlayfs/ovl_entry.h b/fs/overlayfs/ovl_entry.h
new file mode 100644
index 0000000..ec23703
--- /dev/null
+++ b/fs/overlayfs/ovl_entry.h
@@ -0,0 +1,115 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+struct ovl_config {
+ char *lowerdir;
+ char *upperdir;
+ char *workdir;
+ bool default_permissions;
+ bool redirect_dir;
+ bool redirect_follow;
+ const char *redirect_mode;
+ bool index;
+ bool nfs_export;
+ int xino;
+ bool metacopy;
+};
+
+struct ovl_sb {
+ struct super_block *sb;
+ dev_t pseudo_dev;
+};
+
+struct ovl_layer {
+ struct vfsmount *mnt;
+ struct ovl_sb *fs;
+ /* Index of this layer in fs root (upper idx == 0) */
+ int idx;
+ /* One fsid per unique underlying sb (upper fsid == 0) */
+ int fsid;
+};
+
+struct ovl_path {
+ struct ovl_layer *layer;
+ struct dentry *dentry;
+};
+
+/* private information held for overlayfs's superblock */
+struct ovl_fs {
+ struct vfsmount *upper_mnt;
+ unsigned int numlower;
+ /* Number of unique lower sb that differ from upper sb */
+ unsigned int numlowerfs;
+ struct ovl_layer *lower_layers;
+ struct ovl_sb *lower_fs;
+ /* workbasedir is the path at workdir= mount option */
+ struct dentry *workbasedir;
+ /* workdir is the 'work' directory under workbasedir */
+ struct dentry *workdir;
+ /* index directory listing overlay inodes by origin file handle */
+ struct dentry *indexdir;
+ long namelen;
+ /* pathnames of lower and upper dirs, for show_options */
+ struct ovl_config config;
+ /* creds of process who forced instantiation of super block */
+ const struct cred *creator_cred;
+ bool tmpfile;
+ bool noxattr;
+ /* Did we take the inuse lock? */
+ bool upperdir_locked;
+ bool workdir_locked;
+ /* Inode numbers in all layers do not use the high xino_bits */
+ unsigned int xino_bits;
+};
+
+/* private information held for every overlayfs dentry */
+struct ovl_entry {
+ union {
+ struct {
+ unsigned long flags;
+ };
+ struct rcu_head rcu;
+ };
+ unsigned numlower;
+ struct ovl_path lowerstack[];
+};
+
+struct ovl_entry *ovl_alloc_entry(unsigned int numlower);
+
+static inline struct ovl_entry *OVL_E(struct dentry *dentry)
+{
+ return (struct ovl_entry *) dentry->d_fsdata;
+}
+
+struct ovl_inode {
+ union {
+ struct ovl_dir_cache *cache; /* directory */
+ struct inode *lowerdata; /* regular file */
+ };
+ const char *redirect;
+ u64 version;
+ unsigned long flags;
+ struct inode vfs_inode;
+ struct dentry *__upperdentry;
+ struct inode *lower;
+
+ /* synchronize copy up and more */
+ struct mutex lock;
+};
+
+static inline struct ovl_inode *OVL_I(struct inode *inode)
+{
+ return container_of(inode, struct ovl_inode, vfs_inode);
+}
+
+static inline struct dentry *ovl_upperdentry_dereference(struct ovl_inode *oi)
+{
+ return READ_ONCE(oi->__upperdentry);
+}
diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c
new file mode 100644
index 0000000..cc8303a
--- /dev/null
+++ b/fs/overlayfs/readdir.c
@@ -0,0 +1,1155 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/file.h>
+#include <linux/xattr.h>
+#include <linux/rbtree.h>
+#include <linux/security.h>
+#include <linux/cred.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+struct ovl_cache_entry {
+ unsigned int len;
+ unsigned int type;
+ u64 real_ino;
+ u64 ino;
+ struct list_head l_node;
+ struct rb_node node;
+ struct ovl_cache_entry *next_maybe_whiteout;
+ bool is_upper;
+ bool is_whiteout;
+ char name[];
+};
+
+struct ovl_dir_cache {
+ long refcount;
+ u64 version;
+ struct list_head entries;
+ struct rb_root root;
+};
+
+struct ovl_readdir_data {
+ struct dir_context ctx;
+ struct dentry *dentry;
+ bool is_lowest;
+ struct rb_root *root;
+ struct list_head *list;
+ struct list_head middle;
+ struct ovl_cache_entry *first_maybe_whiteout;
+ int count;
+ int err;
+ bool is_upper;
+ bool d_type_supported;
+};
+
+struct ovl_dir_file {
+ bool is_real;
+ bool is_upper;
+ struct ovl_dir_cache *cache;
+ struct list_head *cursor;
+ struct file *realfile;
+ struct file *upperfile;
+};
+
+static struct ovl_cache_entry *ovl_cache_entry_from_node(struct rb_node *n)
+{
+ return rb_entry(n, struct ovl_cache_entry, node);
+}
+
+static bool ovl_cache_entry_find_link(const char *name, int len,
+ struct rb_node ***link,
+ struct rb_node **parent)
+{
+ bool found = false;
+ struct rb_node **newp = *link;
+
+ while (!found && *newp) {
+ int cmp;
+ struct ovl_cache_entry *tmp;
+
+ *parent = *newp;
+ tmp = ovl_cache_entry_from_node(*newp);
+ cmp = strncmp(name, tmp->name, len);
+ if (cmp > 0)
+ newp = &tmp->node.rb_right;
+ else if (cmp < 0 || len < tmp->len)
+ newp = &tmp->node.rb_left;
+ else
+ found = true;
+ }
+ *link = newp;
+
+ return found;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root,
+ const char *name, int len)
+{
+ struct rb_node *node = root->rb_node;
+ int cmp;
+
+ while (node) {
+ struct ovl_cache_entry *p = ovl_cache_entry_from_node(node);
+
+ cmp = strncmp(name, p->name, len);
+ if (cmp > 0)
+ node = p->node.rb_right;
+ else if (cmp < 0 || len < p->len)
+ node = p->node.rb_left;
+ else
+ return p;
+ }
+
+ return NULL;
+}
+
+static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd,
+ struct ovl_cache_entry *p)
+{
+ /* Don't care if not doing ovl_iter() */
+ if (!rdd->dentry)
+ return false;
+
+ /* Always recalc d_ino when remapping lower inode numbers */
+ if (ovl_xino_bits(rdd->dentry->d_sb))
+ return true;
+
+ /* Always recalc d_ino for parent */
+ if (strcmp(p->name, "..") == 0)
+ return true;
+
+ /* If this is lower, then native d_ino will do */
+ if (!rdd->is_upper)
+ return false;
+
+ /*
+ * Recalc d_ino for '.' and for all entries if dir is impure (contains
+ * copied up entries)
+ */
+ if ((p->name[0] == '.' && p->len == 1) ||
+ ovl_test_flag(OVL_IMPURE, d_inode(rdd->dentry)))
+ return true;
+
+ return false;
+}
+
+static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,
+ const char *name, int len,
+ u64 ino, unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+ size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);
+
+ p = kmalloc(size, GFP_KERNEL);
+ if (!p)
+ return NULL;
+
+ memcpy(p->name, name, len);
+ p->name[len] = '\0';
+ p->len = len;
+ p->type = d_type;
+ p->real_ino = ino;
+ p->ino = ino;
+ /* Defer setting d_ino for upper entry to ovl_iterate() */
+ if (ovl_calc_d_ino(rdd, p))
+ p->ino = 0;
+ p->is_upper = rdd->is_upper;
+ p->is_whiteout = false;
+
+ if (d_type == DT_CHR) {
+ p->next_maybe_whiteout = rdd->first_maybe_whiteout;
+ rdd->first_maybe_whiteout = p;
+ }
+ return p;
+}
+
+static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd,
+ const char *name, int len, u64 ino,
+ unsigned int d_type)
+{
+ struct rb_node **newp = &rdd->root->rb_node;
+ struct rb_node *parent = NULL;
+ struct ovl_cache_entry *p;
+
+ if (ovl_cache_entry_find_link(name, len, &newp, &parent))
+ return 0;
+
+ p = ovl_cache_entry_new(rdd, name, len, ino, d_type);
+ if (p == NULL) {
+ rdd->err = -ENOMEM;
+ return -ENOMEM;
+ }
+
+ list_add_tail(&p->l_node, rdd->list);
+ rb_link_node(&p->node, parent, newp);
+ rb_insert_color(&p->node, rdd->root);
+
+ return 0;
+}
+
+static int ovl_fill_lowest(struct ovl_readdir_data *rdd,
+ const char *name, int namelen,
+ loff_t offset, u64 ino, unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+
+ p = ovl_cache_entry_find(rdd->root, name, namelen);
+ if (p) {
+ list_move_tail(&p->l_node, &rdd->middle);
+ } else {
+ p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
+ if (p == NULL)
+ rdd->err = -ENOMEM;
+ else
+ list_add_tail(&p->l_node, &rdd->middle);
+ }
+
+ return rdd->err;
+}
+
+void ovl_cache_free(struct list_head *list)
+{
+ struct ovl_cache_entry *p;
+ struct ovl_cache_entry *n;
+
+ list_for_each_entry_safe(p, n, list, l_node)
+ kfree(p);
+
+ INIT_LIST_HEAD(list);
+}
+
+void ovl_dir_cache_free(struct inode *inode)
+{
+ struct ovl_dir_cache *cache = ovl_dir_cache(inode);
+
+ if (cache) {
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ }
+}
+
+static void ovl_cache_put(struct ovl_dir_file *od, struct dentry *dentry)
+{
+ struct ovl_dir_cache *cache = od->cache;
+
+ WARN_ON(cache->refcount <= 0);
+ cache->refcount--;
+ if (!cache->refcount) {
+ if (ovl_dir_cache(d_inode(dentry)) == cache)
+ ovl_set_dir_cache(d_inode(dentry), NULL);
+
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ }
+}
+
+static int ovl_fill_merge(struct dir_context *ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct ovl_readdir_data *rdd =
+ container_of(ctx, struct ovl_readdir_data, ctx);
+
+ rdd->count++;
+ if (!rdd->is_lowest)
+ return ovl_cache_entry_add_rb(rdd, name, namelen, ino, d_type);
+ else
+ return ovl_fill_lowest(rdd, name, namelen, offset, ino, d_type);
+}
+
+static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)
+{
+ int err;
+ struct ovl_cache_entry *p;
+ struct dentry *dentry;
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(rdd->dentry->d_sb);
+
+ err = down_write_killable(&dir->d_inode->i_rwsem);
+ if (!err) {
+ while (rdd->first_maybe_whiteout) {
+ p = rdd->first_maybe_whiteout;
+ rdd->first_maybe_whiteout = p->next_maybe_whiteout;
+ dentry = lookup_one_len(p->name, dir, p->len);
+ if (!IS_ERR(dentry)) {
+ p->is_whiteout = ovl_is_whiteout(dentry);
+ dput(dentry);
+ }
+ }
+ inode_unlock(dir->d_inode);
+ }
+ revert_creds(old_cred);
+
+ return err;
+}
+
+static inline int ovl_dir_read(struct path *realpath,
+ struct ovl_readdir_data *rdd)
+{
+ struct file *realfile;
+ int err;
+
+ realfile = ovl_path_open(realpath, O_RDONLY | O_DIRECTORY);
+ if (IS_ERR(realfile))
+ return PTR_ERR(realfile);
+
+ rdd->first_maybe_whiteout = NULL;
+ rdd->ctx.pos = 0;
+ do {
+ rdd->count = 0;
+ rdd->err = 0;
+ err = iterate_dir(realfile, &rdd->ctx);
+ if (err >= 0)
+ err = rdd->err;
+ } while (!err && rdd->count);
+
+ if (!err && rdd->first_maybe_whiteout && rdd->dentry)
+ err = ovl_check_whiteouts(realpath->dentry, rdd);
+
+ fput(realfile);
+
+ return err;
+}
+
+/*
+ * Can we iterate real dir directly?
+ *
+ * Non-merge dir may contain whiteouts from a time it was a merge upper, before
+ * lower dir was removed under it and possibly before it was rotated from upper
+ * to lower layer.
+ */
+static bool ovl_dir_is_real(struct dentry *dir)
+{
+ return !ovl_test_flag(OVL_WHITEOUTS, d_inode(dir));
+}
+
+static void ovl_dir_reset(struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct ovl_dir_cache *cache = od->cache;
+ struct dentry *dentry = file->f_path.dentry;
+ bool is_real;
+
+ if (cache && ovl_dentry_version_get(dentry) != cache->version) {
+ ovl_cache_put(od, dentry);
+ od->cache = NULL;
+ od->cursor = NULL;
+ }
+ is_real = ovl_dir_is_real(dentry);
+ if (od->is_real != is_real) {
+ /* is_real can only become false when dir is copied up */
+ if (WARN_ON(is_real))
+ return;
+ od->is_real = false;
+ }
+}
+
+static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list,
+ struct rb_root *root)
+{
+ int err;
+ struct path realpath;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_fill_merge,
+ .dentry = dentry,
+ .list = list,
+ .root = root,
+ .is_lowest = false,
+ };
+ int idx, next;
+
+ for (idx = 0; idx != -1; idx = next) {
+ next = ovl_path_next(idx, dentry, &realpath);
+ rdd.is_upper = ovl_dentry_upper(dentry) == realpath.dentry;
+
+ if (next != -1) {
+ err = ovl_dir_read(&realpath, &rdd);
+ if (err)
+ break;
+ } else {
+ /*
+ * Insert lowest layer entries before upper ones, this
+ * allows offsets to be reasonably constant
+ */
+ list_add(&rdd.middle, rdd.list);
+ rdd.is_lowest = true;
+ err = ovl_dir_read(&realpath, &rdd);
+ list_del(&rdd.middle);
+ }
+ }
+ return err;
+}
+
+static void ovl_seek_cursor(struct ovl_dir_file *od, loff_t pos)
+{
+ struct list_head *p;
+ loff_t off = 0;
+
+ list_for_each(p, &od->cache->entries) {
+ if (off >= pos)
+ break;
+ off++;
+ }
+ /* Cursor is safe since the cache is stable */
+ od->cursor = p;
+}
+
+static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry)
+{
+ int res;
+ struct ovl_dir_cache *cache;
+
+ cache = ovl_dir_cache(d_inode(dentry));
+ if (cache && ovl_dentry_version_get(dentry) == cache->version) {
+ WARN_ON(!cache->refcount);
+ cache->refcount++;
+ return cache;
+ }
+ ovl_set_dir_cache(d_inode(dentry), NULL);
+
+ cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
+ if (!cache)
+ return ERR_PTR(-ENOMEM);
+
+ cache->refcount = 1;
+ INIT_LIST_HEAD(&cache->entries);
+ cache->root = RB_ROOT;
+
+ res = ovl_dir_read_merged(dentry, &cache->entries, &cache->root);
+ if (res) {
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ return ERR_PTR(res);
+ }
+
+ cache->version = ovl_dentry_version_get(dentry);
+ ovl_set_dir_cache(d_inode(dentry), cache);
+
+ return cache;
+}
+
+/* Map inode number to lower fs unique range */
+static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,
+ const char *name, int namelen)
+{
+ if (ino >> (64 - xinobits)) {
+ pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",
+ namelen, name, ino, xinobits);
+ return ino;
+ }
+
+ return ino | ((u64)fsid) << (64 - xinobits);
+}
+
+/*
+ * Set d_ino for upper entries. Non-upper entries should always report
+ * the uppermost real inode ino and should not call this function.
+ *
+ * When not all layer are on same fs, report real ino also for upper.
+ *
+ * When all layers are on the same fs, and upper has a reference to
+ * copy up origin, call vfs_getattr() on the overlay entry to make
+ * sure that d_ino will be consistent with st_ino from stat(2).
+ */
+static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p)
+
+{
+ struct dentry *dir = path->dentry;
+ struct dentry *this = NULL;
+ enum ovl_path_type type;
+ u64 ino = p->real_ino;
+ int xinobits = ovl_xino_bits(dir->d_sb);
+ int err = 0;
+
+ if (!ovl_same_sb(dir->d_sb) && !xinobits)
+ goto out;
+
+ if (p->name[0] == '.') {
+ if (p->len == 1) {
+ this = dget(dir);
+ goto get;
+ }
+ if (p->len == 2 && p->name[1] == '.') {
+ /* we shall not be moved */
+ this = dget(dir->d_parent);
+ goto get;
+ }
+ }
+ this = lookup_one_len(p->name, dir, p->len);
+ if (IS_ERR_OR_NULL(this) || !this->d_inode) {
+ if (IS_ERR(this)) {
+ err = PTR_ERR(this);
+ this = NULL;
+ goto fail;
+ }
+ goto out;
+ }
+
+get:
+ type = ovl_path_type(this);
+ if (OVL_TYPE_ORIGIN(type)) {
+ struct kstat stat;
+ struct path statpath = *path;
+
+ statpath.dentry = this;
+ err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
+ if (err)
+ goto fail;
+
+ WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
+ ino = stat.ino;
+ } else if (xinobits && !OVL_TYPE_UPPER(type)) {
+ ino = ovl_remap_lower_ino(ino, xinobits,
+ ovl_layer_lower(this)->fsid,
+ p->name, p->len);
+ }
+
+out:
+ p->ino = ino;
+ dput(this);
+ return err;
+
+fail:
+ pr_warn_ratelimited("overlayfs: failed to look up (%s) for ino (%i)\n",
+ p->name, err);
+ goto out;
+}
+
+static int ovl_fill_plain(struct dir_context *ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct ovl_cache_entry *p;
+ struct ovl_readdir_data *rdd =
+ container_of(ctx, struct ovl_readdir_data, ctx);
+
+ rdd->count++;
+ p = ovl_cache_entry_new(rdd, name, namelen, ino, d_type);
+ if (p == NULL) {
+ rdd->err = -ENOMEM;
+ return -ENOMEM;
+ }
+ list_add_tail(&p->l_node, rdd->list);
+
+ return 0;
+}
+
+static int ovl_dir_read_impure(struct path *path, struct list_head *list,
+ struct rb_root *root)
+{
+ int err;
+ struct path realpath;
+ struct ovl_cache_entry *p, *n;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_fill_plain,
+ .list = list,
+ .root = root,
+ };
+
+ INIT_LIST_HEAD(list);
+ *root = RB_ROOT;
+ ovl_path_upper(path->dentry, &realpath);
+
+ err = ovl_dir_read(&realpath, &rdd);
+ if (err)
+ return err;
+
+ list_for_each_entry_safe(p, n, list, l_node) {
+ if (strcmp(p->name, ".") != 0 &&
+ strcmp(p->name, "..") != 0) {
+ err = ovl_cache_update_ino(path, p);
+ if (err)
+ return err;
+ }
+ if (p->ino == p->real_ino) {
+ list_del(&p->l_node);
+ kfree(p);
+ } else {
+ struct rb_node **newp = &root->rb_node;
+ struct rb_node *parent = NULL;
+
+ if (WARN_ON(ovl_cache_entry_find_link(p->name, p->len,
+ &newp, &parent)))
+ return -EIO;
+
+ rb_link_node(&p->node, parent, newp);
+ rb_insert_color(&p->node, root);
+ }
+ }
+ return 0;
+}
+
+static struct ovl_dir_cache *ovl_cache_get_impure(struct path *path)
+{
+ int res;
+ struct dentry *dentry = path->dentry;
+ struct ovl_dir_cache *cache;
+
+ cache = ovl_dir_cache(d_inode(dentry));
+ if (cache && ovl_dentry_version_get(dentry) == cache->version)
+ return cache;
+
+ /* Impure cache is not refcounted, free it here */
+ ovl_dir_cache_free(d_inode(dentry));
+ ovl_set_dir_cache(d_inode(dentry), NULL);
+
+ cache = kzalloc(sizeof(struct ovl_dir_cache), GFP_KERNEL);
+ if (!cache)
+ return ERR_PTR(-ENOMEM);
+
+ res = ovl_dir_read_impure(path, &cache->entries, &cache->root);
+ if (res) {
+ ovl_cache_free(&cache->entries);
+ kfree(cache);
+ return ERR_PTR(res);
+ }
+ if (list_empty(&cache->entries)) {
+ /*
+ * A good opportunity to get rid of an unneeded "impure" flag.
+ * Removing the "impure" xattr is best effort.
+ */
+ if (!ovl_want_write(dentry)) {
+ ovl_do_removexattr(ovl_dentry_upper(dentry),
+ OVL_XATTR_IMPURE);
+ ovl_drop_write(dentry);
+ }
+ ovl_clear_flag(OVL_IMPURE, d_inode(dentry));
+ kfree(cache);
+ return NULL;
+ }
+
+ cache->version = ovl_dentry_version_get(dentry);
+ ovl_set_dir_cache(d_inode(dentry), cache);
+
+ return cache;
+}
+
+struct ovl_readdir_translate {
+ struct dir_context *orig_ctx;
+ struct ovl_dir_cache *cache;
+ struct dir_context ctx;
+ u64 parent_ino;
+ int fsid;
+ int xinobits;
+};
+
+static int ovl_fill_real(struct dir_context *ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct ovl_readdir_translate *rdt =
+ container_of(ctx, struct ovl_readdir_translate, ctx);
+ struct dir_context *orig_ctx = rdt->orig_ctx;
+
+ if (rdt->parent_ino && strcmp(name, "..") == 0) {
+ ino = rdt->parent_ino;
+ } else if (rdt->cache) {
+ struct ovl_cache_entry *p;
+
+ p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);
+ if (p)
+ ino = p->ino;
+ } else if (rdt->xinobits) {
+ ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,
+ name, namelen);
+ }
+
+ return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
+}
+
+static bool ovl_is_impure_dir(struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct inode *dir = d_inode(file->f_path.dentry);
+
+ /*
+ * Only upper dir can be impure, but if we are in the middle of
+ * iterating a lower real dir, dir could be copied up and marked
+ * impure. We only want the impure cache if we started iterating
+ * a real upper dir to begin with.
+ */
+ return od->is_upper && ovl_test_flag(OVL_IMPURE, dir);
+
+}
+
+static int ovl_iterate_real(struct file *file, struct dir_context *ctx)
+{
+ int err;
+ struct ovl_dir_file *od = file->private_data;
+ struct dentry *dir = file->f_path.dentry;
+ struct ovl_layer *lower_layer = ovl_layer_lower(dir);
+ struct ovl_readdir_translate rdt = {
+ .ctx.actor = ovl_fill_real,
+ .orig_ctx = ctx,
+ .xinobits = ovl_xino_bits(dir->d_sb),
+ };
+
+ if (rdt.xinobits && lower_layer)
+ rdt.fsid = lower_layer->fsid;
+
+ if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {
+ struct kstat stat;
+ struct path statpath = file->f_path;
+
+ statpath.dentry = dir->d_parent;
+ err = vfs_getattr(&statpath, &stat, STATX_INO, 0);
+ if (err)
+ return err;
+
+ WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);
+ rdt.parent_ino = stat.ino;
+ }
+
+ if (ovl_is_impure_dir(file)) {
+ rdt.cache = ovl_cache_get_impure(&file->f_path);
+ if (IS_ERR(rdt.cache))
+ return PTR_ERR(rdt.cache);
+ }
+
+ err = iterate_dir(od->realfile, &rdt.ctx);
+ ctx->pos = rdt.ctx.pos;
+
+ return err;
+}
+
+
+static int ovl_iterate(struct file *file, struct dir_context *ctx)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct dentry *dentry = file->f_path.dentry;
+ struct ovl_cache_entry *p;
+ int err;
+
+ if (!ctx->pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real) {
+ /*
+ * If parent is merge, then need to adjust d_ino for '..', if
+ * dir is impure then need to adjust d_ino for copied up
+ * entries.
+ */
+ if (ovl_xino_bits(dentry->d_sb) ||
+ (ovl_same_sb(dentry->d_sb) &&
+ (ovl_is_impure_dir(file) ||
+ OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {
+ return ovl_iterate_real(file, ctx);
+ }
+ return iterate_dir(od->realfile, ctx);
+ }
+
+ if (!od->cache) {
+ struct ovl_dir_cache *cache;
+
+ cache = ovl_cache_get(dentry);
+ if (IS_ERR(cache))
+ return PTR_ERR(cache);
+
+ od->cache = cache;
+ ovl_seek_cursor(od, ctx->pos);
+ }
+
+ while (od->cursor != &od->cache->entries) {
+ p = list_entry(od->cursor, struct ovl_cache_entry, l_node);
+ if (!p->is_whiteout) {
+ if (!p->ino) {
+ err = ovl_cache_update_ino(&file->f_path, p);
+ if (err)
+ return err;
+ }
+ if (!dir_emit(ctx, p->name, p->len, p->ino, p->type))
+ break;
+ }
+ od->cursor = p->l_node.next;
+ ctx->pos++;
+ }
+ return 0;
+}
+
+static loff_t ovl_dir_llseek(struct file *file, loff_t offset, int origin)
+{
+ loff_t res;
+ struct ovl_dir_file *od = file->private_data;
+
+ inode_lock(file_inode(file));
+ if (!file->f_pos)
+ ovl_dir_reset(file);
+
+ if (od->is_real) {
+ res = vfs_llseek(od->realfile, offset, origin);
+ file->f_pos = od->realfile->f_pos;
+ } else {
+ res = -EINVAL;
+
+ switch (origin) {
+ case SEEK_CUR:
+ offset += file->f_pos;
+ break;
+ case SEEK_SET:
+ break;
+ default:
+ goto out_unlock;
+ }
+ if (offset < 0)
+ goto out_unlock;
+
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (od->cache)
+ ovl_seek_cursor(od, offset);
+ }
+ res = offset;
+ }
+out_unlock:
+ inode_unlock(file_inode(file));
+
+ return res;
+}
+
+static int ovl_dir_fsync(struct file *file, loff_t start, loff_t end,
+ int datasync)
+{
+ struct ovl_dir_file *od = file->private_data;
+ struct dentry *dentry = file->f_path.dentry;
+ struct file *realfile = od->realfile;
+
+ /* Nothing to sync for lower */
+ if (!OVL_TYPE_UPPER(ovl_path_type(dentry)))
+ return 0;
+
+ /*
+ * Need to check if we started out being a lower dir, but got copied up
+ */
+ if (!od->is_upper) {
+ struct inode *inode = file_inode(file);
+
+ realfile = READ_ONCE(od->upperfile);
+ if (!realfile) {
+ struct path upperpath;
+
+ ovl_path_upper(dentry, &upperpath);
+ realfile = ovl_path_open(&upperpath, O_RDONLY);
+
+ inode_lock(inode);
+ if (!od->upperfile) {
+ if (IS_ERR(realfile)) {
+ inode_unlock(inode);
+ return PTR_ERR(realfile);
+ }
+ smp_store_release(&od->upperfile, realfile);
+ } else {
+ /* somebody has beaten us to it */
+ if (!IS_ERR(realfile))
+ fput(realfile);
+ realfile = od->upperfile;
+ }
+ inode_unlock(inode);
+ }
+ }
+
+ return vfs_fsync_range(realfile, start, end, datasync);
+}
+
+static int ovl_dir_release(struct inode *inode, struct file *file)
+{
+ struct ovl_dir_file *od = file->private_data;
+
+ if (od->cache) {
+ inode_lock(inode);
+ ovl_cache_put(od, file->f_path.dentry);
+ inode_unlock(inode);
+ }
+ fput(od->realfile);
+ if (od->upperfile)
+ fput(od->upperfile);
+ kfree(od);
+
+ return 0;
+}
+
+static int ovl_dir_open(struct inode *inode, struct file *file)
+{
+ struct path realpath;
+ struct file *realfile;
+ struct ovl_dir_file *od;
+ enum ovl_path_type type;
+
+ od = kzalloc(sizeof(struct ovl_dir_file), GFP_KERNEL);
+ if (!od)
+ return -ENOMEM;
+
+ type = ovl_path_real(file->f_path.dentry, &realpath);
+ realfile = ovl_path_open(&realpath, file->f_flags);
+ if (IS_ERR(realfile)) {
+ kfree(od);
+ return PTR_ERR(realfile);
+ }
+ od->realfile = realfile;
+ od->is_real = ovl_dir_is_real(file->f_path.dentry);
+ od->is_upper = OVL_TYPE_UPPER(type);
+ file->private_data = od;
+
+ return 0;
+}
+
+const struct file_operations ovl_dir_operations = {
+ .read = generic_read_dir,
+ .open = ovl_dir_open,
+ .iterate = ovl_iterate,
+ .llseek = ovl_dir_llseek,
+ .fsync = ovl_dir_fsync,
+ .release = ovl_dir_release,
+};
+
+int ovl_check_empty_dir(struct dentry *dentry, struct list_head *list)
+{
+ int err;
+ struct ovl_cache_entry *p, *n;
+ struct rb_root root = RB_ROOT;
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ err = ovl_dir_read_merged(dentry, list, &root);
+ revert_creds(old_cred);
+ if (err)
+ return err;
+
+ err = 0;
+
+ list_for_each_entry_safe(p, n, list, l_node) {
+ /*
+ * Select whiteouts in upperdir, they should
+ * be cleared when deleting this directory.
+ */
+ if (p->is_whiteout) {
+ if (p->is_upper)
+ continue;
+ goto del_entry;
+ }
+
+ if (p->name[0] == '.') {
+ if (p->len == 1)
+ goto del_entry;
+ if (p->len == 2 && p->name[1] == '.')
+ goto del_entry;
+ }
+ err = -ENOTEMPTY;
+ break;
+
+del_entry:
+ list_del(&p->l_node);
+ kfree(p);
+ }
+
+ return err;
+}
+
+void ovl_cleanup_whiteouts(struct dentry *upper, struct list_head *list)
+{
+ struct ovl_cache_entry *p;
+
+ inode_lock_nested(upper->d_inode, I_MUTEX_CHILD);
+ list_for_each_entry(p, list, l_node) {
+ struct dentry *dentry;
+
+ if (WARN_ON(!p->is_whiteout || !p->is_upper))
+ continue;
+
+ dentry = lookup_one_len(p->name, upper, p->len);
+ if (IS_ERR(dentry)) {
+ pr_err("overlayfs: lookup '%s/%.*s' failed (%i)\n",
+ upper->d_name.name, p->len, p->name,
+ (int) PTR_ERR(dentry));
+ continue;
+ }
+ if (dentry->d_inode)
+ ovl_cleanup(upper->d_inode, dentry);
+ dput(dentry);
+ }
+ inode_unlock(upper->d_inode);
+}
+
+static int ovl_check_d_type(struct dir_context *ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct ovl_readdir_data *rdd =
+ container_of(ctx, struct ovl_readdir_data, ctx);
+
+ /* Even if d_type is not supported, DT_DIR is returned for . and .. */
+ if (!strncmp(name, ".", namelen) || !strncmp(name, "..", namelen))
+ return 0;
+
+ if (d_type != DT_UNKNOWN)
+ rdd->d_type_supported = true;
+
+ return 0;
+}
+
+/*
+ * Returns 1 if d_type is supported, 0 not supported/unknown. Negative values
+ * if error is encountered.
+ */
+int ovl_check_d_type_supported(struct path *realpath)
+{
+ int err;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_check_d_type,
+ .d_type_supported = false,
+ };
+
+ err = ovl_dir_read(realpath, &rdd);
+ if (err)
+ return err;
+
+ return rdd.d_type_supported;
+}
+
+static void ovl_workdir_cleanup_recurse(struct path *path, int level)
+{
+ int err;
+ struct inode *dir = path->dentry->d_inode;
+ LIST_HEAD(list);
+ struct rb_root root = RB_ROOT;
+ struct ovl_cache_entry *p;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_fill_merge,
+ .dentry = NULL,
+ .list = &list,
+ .root = &root,
+ .is_lowest = false,
+ };
+
+ err = ovl_dir_read(path, &rdd);
+ if (err)
+ goto out;
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ list_for_each_entry(p, &list, l_node) {
+ struct dentry *dentry;
+
+ if (p->name[0] == '.') {
+ if (p->len == 1)
+ continue;
+ if (p->len == 2 && p->name[1] == '.')
+ continue;
+ }
+ dentry = lookup_one_len(p->name, path->dentry, p->len);
+ if (IS_ERR(dentry))
+ continue;
+ if (dentry->d_inode)
+ ovl_workdir_cleanup(dir, path->mnt, dentry, level);
+ dput(dentry);
+ }
+ inode_unlock(dir);
+out:
+ ovl_cache_free(&list);
+}
+
+void ovl_workdir_cleanup(struct inode *dir, struct vfsmount *mnt,
+ struct dentry *dentry, int level)
+{
+ int err;
+
+ if (!d_is_dir(dentry) || level > 1) {
+ ovl_cleanup(dir, dentry);
+ return;
+ }
+
+ err = ovl_do_rmdir(dir, dentry);
+ if (err) {
+ struct path path = { .mnt = mnt, .dentry = dentry };
+
+ inode_unlock(dir);
+ ovl_workdir_cleanup_recurse(&path, level + 1);
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ ovl_cleanup(dir, dentry);
+ }
+}
+
+int ovl_indexdir_cleanup(struct ovl_fs *ofs)
+{
+ int err;
+ struct dentry *indexdir = ofs->indexdir;
+ struct dentry *index = NULL;
+ struct inode *dir = indexdir->d_inode;
+ struct path path = { .mnt = ofs->upper_mnt, .dentry = indexdir };
+ LIST_HEAD(list);
+ struct rb_root root = RB_ROOT;
+ struct ovl_cache_entry *p;
+ struct ovl_readdir_data rdd = {
+ .ctx.actor = ovl_fill_merge,
+ .dentry = NULL,
+ .list = &list,
+ .root = &root,
+ .is_lowest = false,
+ };
+
+ err = ovl_dir_read(&path, &rdd);
+ if (err)
+ goto out;
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ list_for_each_entry(p, &list, l_node) {
+ if (p->name[0] == '.') {
+ if (p->len == 1)
+ continue;
+ if (p->len == 2 && p->name[1] == '.')
+ continue;
+ }
+ index = lookup_one_len(p->name, indexdir, p->len);
+ if (IS_ERR(index)) {
+ err = PTR_ERR(index);
+ index = NULL;
+ break;
+ }
+ err = ovl_verify_index(ofs, index);
+ if (!err) {
+ goto next;
+ } else if (err == -ESTALE) {
+ /* Cleanup stale index entries */
+ err = ovl_cleanup(dir, index);
+ } else if (err != -ENOENT) {
+ /*
+ * Abort mount to avoid corrupting the index if
+ * an incompatible index entry was found or on out
+ * of memory.
+ */
+ break;
+ } else if (ofs->config.nfs_export) {
+ /*
+ * Whiteout orphan index to block future open by
+ * handle after overlay nlink dropped to zero.
+ */
+ err = ovl_cleanup_and_whiteout(indexdir, dir, index);
+ } else {
+ /* Cleanup orphan index entries */
+ err = ovl_cleanup(dir, index);
+ }
+
+ if (err)
+ break;
+
+next:
+ dput(index);
+ index = NULL;
+ }
+ dput(index);
+ inode_unlock(dir);
+out:
+ ovl_cache_free(&list);
+ if (err)
+ pr_err("overlayfs: failed index dir cleanup (%i)\n", err);
+ return err;
+}
diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c
new file mode 100644
index 0000000..0fb0a59
--- /dev/null
+++ b/fs/overlayfs/super.c
@@ -0,0 +1,1591 @@
+/*
+ *
+ * Copyright (C) 2011 Novell Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <uapi/linux/magic.h>
+#include <linux/fs.h>
+#include <linux/namei.h>
+#include <linux/xattr.h>
+#include <linux/mount.h>
+#include <linux/parser.h>
+#include <linux/module.h>
+#include <linux/statfs.h>
+#include <linux/seq_file.h>
+#include <linux/posix_acl_xattr.h>
+#include <linux/exportfs.h>
+#include "overlayfs.h"
+
+MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
+MODULE_DESCRIPTION("Overlay filesystem");
+MODULE_LICENSE("GPL");
+
+
+struct ovl_dir_cache;
+
+#define OVL_MAX_STACK 500
+
+static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
+module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
+MODULE_PARM_DESC(ovl_redirect_dir_def,
+ "Default to on or off for the redirect_dir feature");
+
+static bool ovl_redirect_always_follow =
+ IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
+module_param_named(redirect_always_follow, ovl_redirect_always_follow,
+ bool, 0644);
+MODULE_PARM_DESC(ovl_redirect_always_follow,
+ "Follow redirects even if redirect_dir feature is turned off");
+
+static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
+module_param_named(index, ovl_index_def, bool, 0644);
+MODULE_PARM_DESC(ovl_index_def,
+ "Default to on or off for the inodes index feature");
+
+static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
+module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
+MODULE_PARM_DESC(ovl_nfs_export_def,
+ "Default to on or off for the NFS export feature");
+
+static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
+module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
+MODULE_PARM_DESC(ovl_xino_auto_def,
+ "Auto enable xino feature");
+
+static void ovl_entry_stack_free(struct ovl_entry *oe)
+{
+ unsigned int i;
+
+ for (i = 0; i < oe->numlower; i++)
+ dput(oe->lowerstack[i].dentry);
+}
+
+static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
+module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
+MODULE_PARM_DESC(ovl_metacopy_def,
+ "Default to on or off for the metadata only copy up feature");
+
+static void ovl_dentry_release(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe) {
+ ovl_entry_stack_free(oe);
+ kfree_rcu(oe, rcu);
+ }
+}
+
+static struct dentry *ovl_d_real(struct dentry *dentry,
+ const struct inode *inode)
+{
+ struct dentry *real;
+
+ /* It's an overlay file */
+ if (inode && d_inode(dentry) == inode)
+ return dentry;
+
+ if (!d_is_reg(dentry)) {
+ if (!inode || inode == d_inode(dentry))
+ return dentry;
+ goto bug;
+ }
+
+ real = ovl_dentry_upper(dentry);
+ if (real && (inode == d_inode(real)))
+ return real;
+
+ if (real && !inode && ovl_has_upperdata(d_inode(dentry)))
+ return real;
+
+ real = ovl_dentry_lowerdata(dentry);
+ if (!real)
+ goto bug;
+
+ /* Handle recursion */
+ real = d_real(real, inode);
+
+ if (!inode || inode == d_inode(real))
+ return real;
+bug:
+ WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry,
+ inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0);
+ return dentry;
+}
+
+static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_REVALIDATE) {
+ ret = d->d_op->d_revalidate(d, flags);
+ if (ret < 0)
+ return ret;
+ if (!ret) {
+ if (!(flags & LOOKUP_RCU))
+ d_invalidate(d);
+ return -ESTALE;
+ }
+ }
+ }
+ return 1;
+}
+
+static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ unsigned int i;
+ int ret = 1;
+
+ for (i = 0; i < oe->numlower; i++) {
+ struct dentry *d = oe->lowerstack[i].dentry;
+
+ if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {
+ ret = d->d_op->d_weak_revalidate(d, flags);
+ if (ret <= 0)
+ break;
+ }
+ }
+ return ret;
+}
+
+static const struct dentry_operations ovl_dentry_operations = {
+ .d_release = ovl_dentry_release,
+ .d_real = ovl_d_real,
+};
+
+static const struct dentry_operations ovl_reval_dentry_operations = {
+ .d_release = ovl_dentry_release,
+ .d_real = ovl_d_real,
+ .d_revalidate = ovl_dentry_revalidate,
+ .d_weak_revalidate = ovl_dentry_weak_revalidate,
+};
+
+static struct kmem_cache *ovl_inode_cachep;
+
+static struct inode *ovl_alloc_inode(struct super_block *sb)
+{
+ struct ovl_inode *oi = kmem_cache_alloc(ovl_inode_cachep, GFP_KERNEL);
+
+ if (!oi)
+ return NULL;
+
+ oi->cache = NULL;
+ oi->redirect = NULL;
+ oi->version = 0;
+ oi->flags = 0;
+ oi->__upperdentry = NULL;
+ oi->lower = NULL;
+ oi->lowerdata = NULL;
+ mutex_init(&oi->lock);
+
+ return &oi->vfs_inode;
+}
+
+static void ovl_i_callback(struct rcu_head *head)
+{
+ struct inode *inode = container_of(head, struct inode, i_rcu);
+
+ kmem_cache_free(ovl_inode_cachep, OVL_I(inode));
+}
+
+static void ovl_destroy_inode(struct inode *inode)
+{
+ struct ovl_inode *oi = OVL_I(inode);
+
+ dput(oi->__upperdentry);
+ iput(oi->lower);
+ if (S_ISDIR(inode->i_mode))
+ ovl_dir_cache_free(inode);
+ else
+ iput(oi->lowerdata);
+ kfree(oi->redirect);
+ mutex_destroy(&oi->lock);
+
+ call_rcu(&inode->i_rcu, ovl_i_callback);
+}
+
+static void ovl_free_fs(struct ovl_fs *ofs)
+{
+ unsigned i;
+
+ dput(ofs->indexdir);
+ dput(ofs->workdir);
+ if (ofs->workdir_locked)
+ ovl_inuse_unlock(ofs->workbasedir);
+ dput(ofs->workbasedir);
+ if (ofs->upperdir_locked)
+ ovl_inuse_unlock(ofs->upper_mnt->mnt_root);
+ mntput(ofs->upper_mnt);
+ for (i = 0; i < ofs->numlower; i++)
+ mntput(ofs->lower_layers[i].mnt);
+ for (i = 0; i < ofs->numlowerfs; i++)
+ free_anon_bdev(ofs->lower_fs[i].pseudo_dev);
+ kfree(ofs->lower_layers);
+ kfree(ofs->lower_fs);
+
+ kfree(ofs->config.lowerdir);
+ kfree(ofs->config.upperdir);
+ kfree(ofs->config.workdir);
+ kfree(ofs->config.redirect_mode);
+ if (ofs->creator_cred)
+ put_cred(ofs->creator_cred);
+ kfree(ofs);
+}
+
+static void ovl_put_super(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ ovl_free_fs(ofs);
+}
+
+/* Sync real dirty inodes in upper filesystem (if it exists) */
+static int ovl_sync_fs(struct super_block *sb, int wait)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+ struct super_block *upper_sb;
+ int ret;
+
+ if (!ofs->upper_mnt)
+ return 0;
+
+ /*
+ * If this is a sync(2) call or an emergency sync, all the super blocks
+ * will be iterated, including upper_sb, so no need to do anything.
+ *
+ * If this is a syncfs(2) call, then we do need to call
+ * sync_filesystem() on upper_sb, but enough if we do it when being
+ * called with wait == 1.
+ */
+ if (!wait)
+ return 0;
+
+ upper_sb = ofs->upper_mnt->mnt_sb;
+
+ down_read(&upper_sb->s_umount);
+ ret = sync_filesystem(upper_sb);
+ up_read(&upper_sb->s_umount);
+
+ return ret;
+}
+
+/**
+ * ovl_statfs
+ * @sb: The overlayfs super block
+ * @buf: The struct kstatfs to fill in with stats
+ *
+ * Get the filesystem statistics. As writes always target the upper layer
+ * filesystem pass the statfs to the upper filesystem (if it exists)
+ */
+static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ struct dentry *root_dentry = dentry->d_sb->s_root;
+ struct path path;
+ int err;
+
+ ovl_path_real(root_dentry, &path);
+
+ err = vfs_statfs(&path, buf);
+ if (!err) {
+ buf->f_namelen = ofs->namelen;
+ buf->f_type = OVERLAYFS_SUPER_MAGIC;
+ }
+
+ return err;
+}
+
+/* Will this overlay be forced to mount/remount ro? */
+static bool ovl_force_readonly(struct ovl_fs *ofs)
+{
+ return (!ofs->upper_mnt || !ofs->workdir);
+}
+
+static const char *ovl_redirect_mode_def(void)
+{
+ return ovl_redirect_dir_def ? "on" : "off";
+}
+
+enum {
+ OVL_XINO_OFF,
+ OVL_XINO_AUTO,
+ OVL_XINO_ON,
+};
+
+static const char * const ovl_xino_str[] = {
+ "off",
+ "auto",
+ "on",
+};
+
+static inline int ovl_xino_def(void)
+{
+ return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
+}
+
+/**
+ * ovl_show_options
+ *
+ * Prints the mount options for a given superblock.
+ * Returns zero; does not fail.
+ */
+static int ovl_show_options(struct seq_file *m, struct dentry *dentry)
+{
+ struct super_block *sb = dentry->d_sb;
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ seq_show_option(m, "lowerdir", ofs->config.lowerdir);
+ if (ofs->config.upperdir) {
+ seq_show_option(m, "upperdir", ofs->config.upperdir);
+ seq_show_option(m, "workdir", ofs->config.workdir);
+ }
+ if (ofs->config.default_permissions)
+ seq_puts(m, ",default_permissions");
+ if (strcmp(ofs->config.redirect_mode, ovl_redirect_mode_def()) != 0)
+ seq_printf(m, ",redirect_dir=%s", ofs->config.redirect_mode);
+ if (ofs->config.index != ovl_index_def)
+ seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
+ if (ofs->config.nfs_export != ovl_nfs_export_def)
+ seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
+ "on" : "off");
+ if (ofs->config.xino != ovl_xino_def())
+ seq_printf(m, ",xino=%s", ovl_xino_str[ofs->config.xino]);
+ if (ofs->config.metacopy != ovl_metacopy_def)
+ seq_printf(m, ",metacopy=%s",
+ ofs->config.metacopy ? "on" : "off");
+ return 0;
+}
+
+static int ovl_remount(struct super_block *sb, int *flags, char *data)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ if (!(*flags & SB_RDONLY) && ovl_force_readonly(ofs))
+ return -EROFS;
+
+ return 0;
+}
+
+static const struct super_operations ovl_super_operations = {
+ .alloc_inode = ovl_alloc_inode,
+ .destroy_inode = ovl_destroy_inode,
+ .drop_inode = generic_delete_inode,
+ .put_super = ovl_put_super,
+ .sync_fs = ovl_sync_fs,
+ .statfs = ovl_statfs,
+ .show_options = ovl_show_options,
+ .remount_fs = ovl_remount,
+};
+
+enum {
+ OPT_LOWERDIR,
+ OPT_UPPERDIR,
+ OPT_WORKDIR,
+ OPT_DEFAULT_PERMISSIONS,
+ OPT_REDIRECT_DIR,
+ OPT_INDEX_ON,
+ OPT_INDEX_OFF,
+ OPT_NFS_EXPORT_ON,
+ OPT_NFS_EXPORT_OFF,
+ OPT_XINO_ON,
+ OPT_XINO_OFF,
+ OPT_XINO_AUTO,
+ OPT_METACOPY_ON,
+ OPT_METACOPY_OFF,
+ OPT_ERR,
+};
+
+static const match_table_t ovl_tokens = {
+ {OPT_LOWERDIR, "lowerdir=%s"},
+ {OPT_UPPERDIR, "upperdir=%s"},
+ {OPT_WORKDIR, "workdir=%s"},
+ {OPT_DEFAULT_PERMISSIONS, "default_permissions"},
+ {OPT_REDIRECT_DIR, "redirect_dir=%s"},
+ {OPT_INDEX_ON, "index=on"},
+ {OPT_INDEX_OFF, "index=off"},
+ {OPT_NFS_EXPORT_ON, "nfs_export=on"},
+ {OPT_NFS_EXPORT_OFF, "nfs_export=off"},
+ {OPT_XINO_ON, "xino=on"},
+ {OPT_XINO_OFF, "xino=off"},
+ {OPT_XINO_AUTO, "xino=auto"},
+ {OPT_METACOPY_ON, "metacopy=on"},
+ {OPT_METACOPY_OFF, "metacopy=off"},
+ {OPT_ERR, NULL}
+};
+
+static char *ovl_next_opt(char **s)
+{
+ char *sbegin = *s;
+ char *p;
+
+ if (sbegin == NULL)
+ return NULL;
+
+ for (p = sbegin; *p; p++) {
+ if (*p == '\\') {
+ p++;
+ if (!*p)
+ break;
+ } else if (*p == ',') {
+ *p = '\0';
+ *s = p + 1;
+ return sbegin;
+ }
+ }
+ *s = NULL;
+ return sbegin;
+}
+
+static int ovl_parse_redirect_mode(struct ovl_config *config, const char *mode)
+{
+ if (strcmp(mode, "on") == 0) {
+ config->redirect_dir = true;
+ /*
+ * Does not make sense to have redirect creation without
+ * redirect following.
+ */
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "follow") == 0) {
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "off") == 0) {
+ if (ovl_redirect_always_follow)
+ config->redirect_follow = true;
+ } else if (strcmp(mode, "nofollow") != 0) {
+ pr_err("overlayfs: bad mount option \"redirect_dir=%s\"\n",
+ mode);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int ovl_parse_opt(char *opt, struct ovl_config *config)
+{
+ char *p;
+ int err;
+ bool metacopy_opt = false, redirect_opt = false;
+
+ config->redirect_mode = kstrdup(ovl_redirect_mode_def(), GFP_KERNEL);
+ if (!config->redirect_mode)
+ return -ENOMEM;
+
+ while ((p = ovl_next_opt(&opt)) != NULL) {
+ int token;
+ substring_t args[MAX_OPT_ARGS];
+
+ if (!*p)
+ continue;
+
+ token = match_token(p, ovl_tokens, args);
+ switch (token) {
+ case OPT_UPPERDIR:
+ kfree(config->upperdir);
+ config->upperdir = match_strdup(&args[0]);
+ if (!config->upperdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_LOWERDIR:
+ kfree(config->lowerdir);
+ config->lowerdir = match_strdup(&args[0]);
+ if (!config->lowerdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_WORKDIR:
+ kfree(config->workdir);
+ config->workdir = match_strdup(&args[0]);
+ if (!config->workdir)
+ return -ENOMEM;
+ break;
+
+ case OPT_DEFAULT_PERMISSIONS:
+ config->default_permissions = true;
+ break;
+
+ case OPT_REDIRECT_DIR:
+ kfree(config->redirect_mode);
+ config->redirect_mode = match_strdup(&args[0]);
+ if (!config->redirect_mode)
+ return -ENOMEM;
+ redirect_opt = true;
+ break;
+
+ case OPT_INDEX_ON:
+ config->index = true;
+ break;
+
+ case OPT_INDEX_OFF:
+ config->index = false;
+ break;
+
+ case OPT_NFS_EXPORT_ON:
+ config->nfs_export = true;
+ break;
+
+ case OPT_NFS_EXPORT_OFF:
+ config->nfs_export = false;
+ break;
+
+ case OPT_XINO_ON:
+ config->xino = OVL_XINO_ON;
+ break;
+
+ case OPT_XINO_OFF:
+ config->xino = OVL_XINO_OFF;
+ break;
+
+ case OPT_XINO_AUTO:
+ config->xino = OVL_XINO_AUTO;
+ break;
+
+ case OPT_METACOPY_ON:
+ config->metacopy = true;
+ metacopy_opt = true;
+ break;
+
+ case OPT_METACOPY_OFF:
+ config->metacopy = false;
+ break;
+
+ default:
+ pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p);
+ return -EINVAL;
+ }
+ }
+
+ /* Workdir is useless in non-upper mount */
+ if (!config->upperdir && config->workdir) {
+ pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
+ config->workdir);
+ kfree(config->workdir);
+ config->workdir = NULL;
+ }
+
+ err = ovl_parse_redirect_mode(config, config->redirect_mode);
+ if (err)
+ return err;
+
+ /*
+ * This is to make the logic below simpler. It doesn't make any other
+ * difference, since config->redirect_dir is only used for upper.
+ */
+ if (!config->upperdir && config->redirect_follow)
+ config->redirect_dir = true;
+
+ /* Resolve metacopy -> redirect_dir dependency */
+ if (config->metacopy && !config->redirect_dir) {
+ if (metacopy_opt && redirect_opt) {
+ pr_err("overlayfs: conflicting options: metacopy=on,redirect_dir=%s\n",
+ config->redirect_mode);
+ return -EINVAL;
+ }
+ if (redirect_opt) {
+ /*
+ * There was an explicit redirect_dir=... that resulted
+ * in this conflict.
+ */
+ pr_info("overlayfs: disabling metacopy due to redirect_dir=%s\n",
+ config->redirect_mode);
+ config->metacopy = false;
+ } else {
+ /* Automatically enable redirect otherwise. */
+ config->redirect_follow = config->redirect_dir = true;
+ }
+ }
+
+ return 0;
+}
+
+#define OVL_WORKDIR_NAME "work"
+#define OVL_INDEXDIR_NAME "index"
+
+static struct dentry *ovl_workdir_create(struct ovl_fs *ofs,
+ const char *name, bool persist)
+{
+ struct inode *dir = ofs->workbasedir->d_inode;
+ struct vfsmount *mnt = ofs->upper_mnt;
+ struct dentry *work;
+ int err;
+ bool retried = false;
+ bool locked = false;
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ locked = true;
+
+retry:
+ work = lookup_one_len(name, ofs->workbasedir, strlen(name));
+
+ if (!IS_ERR(work)) {
+ struct iattr attr = {
+ .ia_valid = ATTR_MODE,
+ .ia_mode = S_IFDIR | 0,
+ };
+
+ if (work->d_inode) {
+ err = -EEXIST;
+ if (retried)
+ goto out_dput;
+
+ if (persist)
+ goto out_unlock;
+
+ retried = true;
+ ovl_workdir_cleanup(dir, mnt, work, 0);
+ dput(work);
+ goto retry;
+ }
+
+ work = ovl_create_real(dir, work, OVL_CATTR(attr.ia_mode));
+ err = PTR_ERR(work);
+ if (IS_ERR(work))
+ goto out_err;
+
+ /*
+ * Try to remove POSIX ACL xattrs from workdir. We are good if:
+ *
+ * a) success (there was a POSIX ACL xattr and was removed)
+ * b) -ENODATA (there was no POSIX ACL xattr)
+ * c) -EOPNOTSUPP (POSIX ACL xattrs are not supported)
+ *
+ * There are various other error values that could effectively
+ * mean that the xattr doesn't exist (e.g. -ERANGE is returned
+ * if the xattr name is too long), but the set of filesystems
+ * allowed as upper are limited to "normal" ones, where checking
+ * for the above two errors is sufficient.
+ */
+ err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT);
+ if (err && err != -ENODATA && err != -EOPNOTSUPP)
+ goto out_dput;
+
+ err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS);
+ if (err && err != -ENODATA && err != -EOPNOTSUPP)
+ goto out_dput;
+
+ /* Clear any inherited mode bits */
+ inode_lock(work->d_inode);
+ err = notify_change(work, &attr, NULL);
+ inode_unlock(work->d_inode);
+ if (err)
+ goto out_dput;
+ } else {
+ err = PTR_ERR(work);
+ goto out_err;
+ }
+out_unlock:
+ if (locked)
+ inode_unlock(dir);
+
+ return work;
+
+out_dput:
+ dput(work);
+out_err:
+ pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n",
+ ofs->config.workdir, name, -err);
+ work = NULL;
+ goto out_unlock;
+}
+
+static void ovl_unescape(char *s)
+{
+ char *d = s;
+
+ for (;; s++, d++) {
+ if (*s == '\\')
+ s++;
+ *d = *s;
+ if (!*s)
+ break;
+ }
+}
+
+static int ovl_mount_dir_noesc(const char *name, struct path *path)
+{
+ int err = -EINVAL;
+
+ if (!*name) {
+ pr_err("overlayfs: empty lowerdir\n");
+ goto out;
+ }
+ err = kern_path(name, LOOKUP_FOLLOW, path);
+ if (err) {
+ pr_err("overlayfs: failed to resolve '%s': %i\n", name, err);
+ goto out;
+ }
+ err = -EINVAL;
+ if (ovl_dentry_weird(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported\n", name);
+ goto out_put;
+ }
+ if (!d_is_dir(path->dentry)) {
+ pr_err("overlayfs: '%s' not a directory\n", name);
+ goto out_put;
+ }
+ return 0;
+
+out_put:
+ path_put_init(path);
+out:
+ return err;
+}
+
+static int ovl_mount_dir(const char *name, struct path *path)
+{
+ int err = -ENOMEM;
+ char *tmp = kstrdup(name, GFP_KERNEL);
+
+ if (tmp) {
+ ovl_unescape(tmp);
+ err = ovl_mount_dir_noesc(tmp, path);
+
+ if (!err)
+ if (ovl_dentry_remote(path->dentry)) {
+ pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",
+ tmp);
+ path_put_init(path);
+ err = -EINVAL;
+ }
+ kfree(tmp);
+ }
+ return err;
+}
+
+static int ovl_check_namelen(struct path *path, struct ovl_fs *ofs,
+ const char *name)
+{
+ struct kstatfs statfs;
+ int err = vfs_statfs(path, &statfs);
+
+ if (err)
+ pr_err("overlayfs: statfs failed on '%s'\n", name);
+ else
+ ofs->namelen = max(ofs->namelen, statfs.f_namelen);
+
+ return err;
+}
+
+static int ovl_lower_dir(const char *name, struct path *path,
+ struct ovl_fs *ofs, int *stack_depth, bool *remote)
+{
+ int fh_type;
+ int err;
+
+ err = ovl_mount_dir_noesc(name, path);
+ if (err)
+ goto out;
+
+ err = ovl_check_namelen(path, ofs, name);
+ if (err)
+ goto out_put;
+
+ *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);
+
+ if (ovl_dentry_remote(path->dentry))
+ *remote = true;
+
+ /*
+ * The inodes index feature and NFS export need to encode and decode
+ * file handles, so they require that all layers support them.
+ */
+ fh_type = ovl_can_decode_fh(path->dentry->d_sb);
+ if ((ofs->config.nfs_export ||
+ (ofs->config.index && ofs->config.upperdir)) && !fh_type) {
+ ofs->config.index = false;
+ ofs->config.nfs_export = false;
+ pr_warn("overlayfs: fs on '%s' does not support file handles, falling back to index=off,nfs_export=off.\n",
+ name);
+ }
+
+ /* Check if lower fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
+ return 0;
+
+out_put:
+ path_put_init(path);
+out:
+ return err;
+}
+
+/* Workdir should not be subdir of upperdir and vice versa */
+static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir)
+{
+ bool ok = false;
+
+ if (workdir != upperdir) {
+ ok = (lock_rename(workdir, upperdir) == NULL);
+ unlock_rename(workdir, upperdir);
+ }
+ return ok;
+}
+
+static unsigned int ovl_split_lowerdirs(char *str)
+{
+ unsigned int ctr = 1;
+ char *s, *d;
+
+ for (s = d = str;; s++, d++) {
+ if (*s == '\\') {
+ s++;
+ } else if (*s == ':') {
+ *d = '\0';
+ ctr++;
+ continue;
+ }
+ *d = *s;
+ if (!*s)
+ break;
+ }
+ return ctr;
+}
+
+static int __maybe_unused
+ovl_posix_acl_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return ovl_xattr_get(dentry, inode, handler->name, buffer, size);
+}
+
+static int __maybe_unused
+ovl_posix_acl_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ struct dentry *workdir = ovl_workdir(dentry);
+ struct inode *realinode = ovl_inode_real(inode);
+ struct posix_acl *acl = NULL;
+ int err;
+
+ /* Check that everything is OK before copy-up */
+ if (value) {
+ acl = posix_acl_from_xattr(&init_user_ns, value, size);
+ if (IS_ERR(acl))
+ return PTR_ERR(acl);
+ }
+ err = -EOPNOTSUPP;
+ if (!IS_POSIXACL(d_inode(workdir)))
+ goto out_acl_release;
+ if (!realinode->i_op->set_acl)
+ goto out_acl_release;
+ if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) {
+ err = acl ? -EACCES : 0;
+ goto out_acl_release;
+ }
+ err = -EPERM;
+ if (!inode_owner_or_capable(inode))
+ goto out_acl_release;
+
+ posix_acl_release(acl);
+
+ /*
+ * Check if sgid bit needs to be cleared (actual setacl operation will
+ * be done with mounter's capabilities and so that won't do it for us).
+ */
+ if (unlikely(inode->i_mode & S_ISGID) &&
+ handler->flags == ACL_TYPE_ACCESS &&
+ !in_group_p(inode->i_gid) &&
+ !capable_wrt_inode_uidgid(inode, CAP_FSETID)) {
+ struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
+
+ err = ovl_setattr(dentry, &iattr);
+ if (err)
+ return err;
+ }
+
+ err = ovl_xattr_set(dentry, inode, handler->name, value, size, flags);
+ if (!err)
+ ovl_copyattr(ovl_inode_real(inode), inode);
+
+ return err;
+
+out_acl_release:
+ posix_acl_release(acl);
+ return err;
+}
+
+static int ovl_own_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ovl_own_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ return -EOPNOTSUPP;
+}
+
+static int ovl_other_xattr_get(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ return ovl_xattr_get(dentry, inode, name, buffer, size);
+}
+
+static int ovl_other_xattr_set(const struct xattr_handler *handler,
+ struct dentry *dentry, struct inode *inode,
+ const char *name, const void *value,
+ size_t size, int flags)
+{
+ return ovl_xattr_set(dentry, inode, name, value, size, flags);
+}
+
+static const struct xattr_handler __maybe_unused
+ovl_posix_acl_access_xattr_handler = {
+ .name = XATTR_NAME_POSIX_ACL_ACCESS,
+ .flags = ACL_TYPE_ACCESS,
+ .get = ovl_posix_acl_xattr_get,
+ .set = ovl_posix_acl_xattr_set,
+};
+
+static const struct xattr_handler __maybe_unused
+ovl_posix_acl_default_xattr_handler = {
+ .name = XATTR_NAME_POSIX_ACL_DEFAULT,
+ .flags = ACL_TYPE_DEFAULT,
+ .get = ovl_posix_acl_xattr_get,
+ .set = ovl_posix_acl_xattr_set,
+};
+
+static const struct xattr_handler ovl_own_xattr_handler = {
+ .prefix = OVL_XATTR_PREFIX,
+ .get = ovl_own_xattr_get,
+ .set = ovl_own_xattr_set,
+};
+
+static const struct xattr_handler ovl_other_xattr_handler = {
+ .prefix = "", /* catch all */
+ .get = ovl_other_xattr_get,
+ .set = ovl_other_xattr_set,
+};
+
+static const struct xattr_handler *ovl_xattr_handlers[] = {
+#ifdef CONFIG_FS_POSIX_ACL
+ &ovl_posix_acl_access_xattr_handler,
+ &ovl_posix_acl_default_xattr_handler,
+#endif
+ &ovl_own_xattr_handler,
+ &ovl_other_xattr_handler,
+ NULL
+};
+
+static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
+{
+ struct vfsmount *upper_mnt;
+ int err;
+
+ err = ovl_mount_dir(ofs->config.upperdir, upperpath);
+ if (err)
+ goto out;
+
+ /* Upper fs should not be r/o */
+ if (sb_rdonly(upperpath->mnt->mnt_sb)) {
+ pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n");
+ err = -EINVAL;
+ goto out;
+ }
+
+ err = ovl_check_namelen(upperpath, ofs, ofs->config.upperdir);
+ if (err)
+ goto out;
+
+ upper_mnt = clone_private_mount(upperpath);
+ err = PTR_ERR(upper_mnt);
+ if (IS_ERR(upper_mnt)) {
+ pr_err("overlayfs: failed to clone upperpath\n");
+ goto out;
+ }
+
+ /* Don't inherit atime flags */
+ upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
+ ofs->upper_mnt = upper_mnt;
+
+ err = -EBUSY;
+ if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {
+ ofs->upperdir_locked = true;
+ } else if (ofs->config.index) {
+ pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
+ goto out;
+ } else {
+ pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static int ovl_make_workdir(struct ovl_fs *ofs, struct path *workpath)
+{
+ struct vfsmount *mnt = ofs->upper_mnt;
+ struct dentry *temp;
+ int fh_type;
+ int err;
+
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
+ ofs->workdir = ovl_workdir_create(ofs, OVL_WORKDIR_NAME, false);
+ if (!ofs->workdir)
+ goto out;
+
+ /*
+ * Upper should support d_type, else whiteouts are visible. Given
+ * workdir and upper are on same fs, we can do iterate_dir() on
+ * workdir. This check requires successful creation of workdir in
+ * previous step.
+ */
+ err = ovl_check_d_type_supported(workpath);
+ if (err < 0)
+ goto out;
+
+ /*
+ * We allowed this configuration and don't want to break users over
+ * kernel upgrade. So warn instead of erroring out.
+ */
+ if (!err)
+ pr_warn("overlayfs: upper fs needs to support d_type.\n");
+
+ /* Check if upper/work fs supports O_TMPFILE */
+ temp = ovl_do_tmpfile(ofs->workdir, S_IFREG | 0);
+ ofs->tmpfile = !IS_ERR(temp);
+ if (ofs->tmpfile)
+ dput(temp);
+ else
+ pr_warn("overlayfs: upper fs does not support tmpfile.\n");
+
+ /*
+ * Check if upper/work fs supports trusted.overlay.* xattr
+ */
+ err = ovl_do_setxattr(ofs->workdir, OVL_XATTR_OPAQUE, "0", 1, 0);
+ if (err) {
+ ofs->noxattr = true;
+ ofs->config.index = false;
+ ofs->config.metacopy = false;
+ pr_warn("overlayfs: upper fs does not support xattr, falling back to index=off and metacopy=off.\n");
+ err = 0;
+ } else {
+ vfs_removexattr(ofs->workdir, OVL_XATTR_OPAQUE);
+ }
+
+ /* Check if upper/work fs supports file handles */
+ fh_type = ovl_can_decode_fh(ofs->workdir->d_sb);
+ if (ofs->config.index && !fh_type) {
+ ofs->config.index = false;
+ pr_warn("overlayfs: upper fs does not support file handles, falling back to index=off.\n");
+ }
+
+ /* Check if upper fs has 32bit inode numbers */
+ if (fh_type != FILEID_INO32_GEN)
+ ofs->xino_bits = 0;
+
+ /* NFS export of r/w mount depends on index */
+ if (ofs->config.nfs_export && !ofs->config.index) {
+ pr_warn("overlayfs: NFS export requires \"index=on\", falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+out:
+ mnt_drop_write(mnt);
+ return err;
+}
+
+static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
+{
+ int err;
+ struct path workpath = { };
+
+ err = ovl_mount_dir(ofs->config.workdir, &workpath);
+ if (err)
+ goto out;
+
+ err = -EINVAL;
+ if (upperpath->mnt != workpath.mnt) {
+ pr_err("overlayfs: workdir and upperdir must reside under the same mount\n");
+ goto out;
+ }
+ if (!ovl_workdir_ok(workpath.dentry, upperpath->dentry)) {
+ pr_err("overlayfs: workdir and upperdir must be separate subtrees\n");
+ goto out;
+ }
+
+ ofs->workbasedir = dget(workpath.dentry);
+
+ err = -EBUSY;
+ if (ovl_inuse_trylock(ofs->workbasedir)) {
+ ofs->workdir_locked = true;
+ } else if (ofs->config.index) {
+ pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
+ goto out;
+ } else {
+ pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
+ }
+
+ err = ovl_make_workdir(ofs, &workpath);
+ if (err)
+ goto out;
+
+ err = 0;
+out:
+ path_put(&workpath);
+
+ return err;
+}
+
+static int ovl_get_indexdir(struct ovl_fs *ofs, struct ovl_entry *oe,
+ struct path *upperpath)
+{
+ struct vfsmount *mnt = ofs->upper_mnt;
+ int err;
+
+ err = mnt_want_write(mnt);
+ if (err)
+ return err;
+
+ /* Verify lower root is upper root origin */
+ err = ovl_verify_origin(upperpath->dentry, oe->lowerstack[0].dentry,
+ true);
+ if (err) {
+ pr_err("overlayfs: failed to verify upper root origin\n");
+ goto out;
+ }
+
+ ofs->indexdir = ovl_workdir_create(ofs, OVL_INDEXDIR_NAME, true);
+ if (ofs->indexdir) {
+ /*
+ * Verify upper root is exclusively associated with index dir.
+ * Older kernels stored upper fh in "trusted.overlay.origin"
+ * xattr. If that xattr exists, verify that it is a match to
+ * upper dir file handle. In any case, verify or set xattr
+ * "trusted.overlay.upper" to indicate that index may have
+ * directory entries.
+ */
+ if (ovl_check_origin_xattr(ofs->indexdir)) {
+ err = ovl_verify_set_fh(ofs->indexdir, OVL_XATTR_ORIGIN,
+ upperpath->dentry, true, false);
+ if (err)
+ pr_err("overlayfs: failed to verify index dir 'origin' xattr\n");
+ }
+ err = ovl_verify_upper(ofs->indexdir, upperpath->dentry, true);
+ if (err)
+ pr_err("overlayfs: failed to verify index dir 'upper' xattr\n");
+
+ /* Cleanup bad/stale/orphan index entries */
+ if (!err)
+ err = ovl_indexdir_cleanup(ofs);
+ }
+ if (err || !ofs->indexdir)
+ pr_warn("overlayfs: try deleting index dir or mounting with '-o index=off' to disable inodes index.\n");
+
+out:
+ mnt_drop_write(mnt);
+ return err;
+}
+
+/* Get a unique fsid for the layer */
+static int ovl_get_fsid(struct ovl_fs *ofs, struct super_block *sb)
+{
+ unsigned int i;
+ dev_t dev;
+ int err;
+
+ /* fsid 0 is reserved for upper fs even with non upper overlay */
+ if (ofs->upper_mnt && ofs->upper_mnt->mnt_sb == sb)
+ return 0;
+
+ for (i = 0; i < ofs->numlowerfs; i++) {
+ if (ofs->lower_fs[i].sb == sb)
+ return i + 1;
+ }
+
+ err = get_anon_bdev(&dev);
+ if (err) {
+ pr_err("overlayfs: failed to get anonymous bdev for lowerpath\n");
+ return err;
+ }
+
+ ofs->lower_fs[ofs->numlowerfs].sb = sb;
+ ofs->lower_fs[ofs->numlowerfs].pseudo_dev = dev;
+ ofs->numlowerfs++;
+
+ return ofs->numlowerfs;
+}
+
+static int ovl_get_lower_layers(struct ovl_fs *ofs, struct path *stack,
+ unsigned int numlower)
+{
+ int err;
+ unsigned int i;
+
+ err = -ENOMEM;
+ ofs->lower_layers = kcalloc(numlower, sizeof(struct ovl_layer),
+ GFP_KERNEL);
+ if (ofs->lower_layers == NULL)
+ goto out;
+
+ ofs->lower_fs = kcalloc(numlower, sizeof(struct ovl_sb),
+ GFP_KERNEL);
+ if (ofs->lower_fs == NULL)
+ goto out;
+
+ for (i = 0; i < numlower; i++) {
+ struct vfsmount *mnt;
+ int fsid;
+
+ err = fsid = ovl_get_fsid(ofs, stack[i].mnt->mnt_sb);
+ if (err < 0)
+ goto out;
+
+ mnt = clone_private_mount(&stack[i]);
+ err = PTR_ERR(mnt);
+ if (IS_ERR(mnt)) {
+ pr_err("overlayfs: failed to clone lowerpath\n");
+ goto out;
+ }
+
+ /*
+ * Make lower layers R/O. That way fchmod/fchown on lower file
+ * will fail instead of modifying lower fs.
+ */
+ mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME;
+
+ ofs->lower_layers[ofs->numlower].mnt = mnt;
+ ofs->lower_layers[ofs->numlower].idx = i + 1;
+ ofs->lower_layers[ofs->numlower].fsid = fsid;
+ if (fsid) {
+ ofs->lower_layers[ofs->numlower].fs =
+ &ofs->lower_fs[fsid - 1];
+ }
+ ofs->numlower++;
+ }
+
+ /*
+ * When all layers on same fs, overlay can use real inode numbers.
+ * With mount option "xino=on", mounter declares that there are enough
+ * free high bits in underlying fs to hold the unique fsid.
+ * If overlayfs does encounter underlying inodes using the high xino
+ * bits reserved for fsid, it emits a warning and uses the original
+ * inode number.
+ */
+ if (!ofs->numlowerfs || (ofs->numlowerfs == 1 && !ofs->upper_mnt)) {
+ ofs->xino_bits = 0;
+ ofs->config.xino = OVL_XINO_OFF;
+ } else if (ofs->config.xino == OVL_XINO_ON && !ofs->xino_bits) {
+ /*
+ * This is a roundup of number of bits needed for numlowerfs+1
+ * (i.e. ilog2(numlowerfs+1 - 1) + 1). fsid 0 is reserved for
+ * upper fs even with non upper overlay.
+ */
+ BUILD_BUG_ON(ilog2(OVL_MAX_STACK) > 31);
+ ofs->xino_bits = ilog2(ofs->numlowerfs) + 1;
+ }
+
+ if (ofs->xino_bits) {
+ pr_info("overlayfs: \"xino\" feature enabled using %d upper inode bits.\n",
+ ofs->xino_bits);
+ }
+
+ err = 0;
+out:
+ return err;
+}
+
+static struct ovl_entry *ovl_get_lowerstack(struct super_block *sb,
+ struct ovl_fs *ofs)
+{
+ int err;
+ char *lowertmp, *lower;
+ struct path *stack = NULL;
+ unsigned int stacklen, numlower = 0, i;
+ bool remote = false;
+ struct ovl_entry *oe;
+
+ err = -ENOMEM;
+ lowertmp = kstrdup(ofs->config.lowerdir, GFP_KERNEL);
+ if (!lowertmp)
+ goto out_err;
+
+ err = -EINVAL;
+ stacklen = ovl_split_lowerdirs(lowertmp);
+ if (stacklen > OVL_MAX_STACK) {
+ pr_err("overlayfs: too many lower directories, limit is %d\n",
+ OVL_MAX_STACK);
+ goto out_err;
+ } else if (!ofs->config.upperdir && stacklen == 1) {
+ pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n");
+ goto out_err;
+ } else if (!ofs->config.upperdir && ofs->config.nfs_export &&
+ ofs->config.redirect_follow) {
+ pr_warn("overlayfs: NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+
+ err = -ENOMEM;
+ stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL);
+ if (!stack)
+ goto out_err;
+
+ err = -EINVAL;
+ lower = lowertmp;
+ for (numlower = 0; numlower < stacklen; numlower++) {
+ err = ovl_lower_dir(lower, &stack[numlower], ofs,
+ &sb->s_stack_depth, &remote);
+ if (err)
+ goto out_err;
+
+ lower = strchr(lower, '\0') + 1;
+ }
+
+ err = -EINVAL;
+ sb->s_stack_depth++;
+ if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
+ pr_err("overlayfs: maximum fs stacking depth exceeded\n");
+ goto out_err;
+ }
+
+ err = ovl_get_lower_layers(ofs, stack, numlower);
+ if (err)
+ goto out_err;
+
+ err = -ENOMEM;
+ oe = ovl_alloc_entry(numlower);
+ if (!oe)
+ goto out_err;
+
+ for (i = 0; i < numlower; i++) {
+ oe->lowerstack[i].dentry = dget(stack[i].dentry);
+ oe->lowerstack[i].layer = &ofs->lower_layers[i];
+ }
+
+ if (remote)
+ sb->s_d_op = &ovl_reval_dentry_operations;
+ else
+ sb->s_d_op = &ovl_dentry_operations;
+
+out:
+ for (i = 0; i < numlower; i++)
+ path_put(&stack[i]);
+ kfree(stack);
+ kfree(lowertmp);
+
+ return oe;
+
+out_err:
+ oe = ERR_PTR(err);
+ goto out;
+}
+
+static int ovl_fill_super(struct super_block *sb, void *data, int silent)
+{
+ struct path upperpath = { };
+ struct dentry *root_dentry;
+ struct ovl_entry *oe;
+ struct ovl_fs *ofs;
+ struct cred *cred;
+ int err;
+
+ err = -ENOMEM;
+ ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
+ if (!ofs)
+ goto out;
+
+ ofs->creator_cred = cred = prepare_creds();
+ if (!cred)
+ goto out_err;
+
+ ofs->config.index = ovl_index_def;
+ ofs->config.nfs_export = ovl_nfs_export_def;
+ ofs->config.xino = ovl_xino_def();
+ ofs->config.metacopy = ovl_metacopy_def;
+ err = ovl_parse_opt((char *) data, &ofs->config);
+ if (err)
+ goto out_err;
+
+ err = -EINVAL;
+ if (!ofs->config.lowerdir) {
+ if (!silent)
+ pr_err("overlayfs: missing 'lowerdir'\n");
+ goto out_err;
+ }
+
+ sb->s_stack_depth = 0;
+ sb->s_maxbytes = MAX_LFS_FILESIZE;
+ /* Assume underlaying fs uses 32bit inodes unless proven otherwise */
+ if (ofs->config.xino != OVL_XINO_OFF)
+ ofs->xino_bits = BITS_PER_LONG - 32;
+
+ if (ofs->config.upperdir) {
+ if (!ofs->config.workdir) {
+ pr_err("overlayfs: missing 'workdir'\n");
+ goto out_err;
+ }
+
+ err = ovl_get_upper(ofs, &upperpath);
+ if (err)
+ goto out_err;
+
+ err = ovl_get_workdir(ofs, &upperpath);
+ if (err)
+ goto out_err;
+
+ if (!ofs->workdir)
+ sb->s_flags |= SB_RDONLY;
+
+ sb->s_stack_depth = ofs->upper_mnt->mnt_sb->s_stack_depth;
+ sb->s_time_gran = ofs->upper_mnt->mnt_sb->s_time_gran;
+
+ }
+ oe = ovl_get_lowerstack(sb, ofs);
+ err = PTR_ERR(oe);
+ if (IS_ERR(oe))
+ goto out_err;
+
+ /* If the upper fs is nonexistent, we mark overlayfs r/o too */
+ if (!ofs->upper_mnt)
+ sb->s_flags |= SB_RDONLY;
+
+ if (!(ovl_force_readonly(ofs)) && ofs->config.index) {
+ err = ovl_get_indexdir(ofs, oe, &upperpath);
+ if (err)
+ goto out_free_oe;
+
+ /* Force r/o mount with no index dir */
+ if (!ofs->indexdir) {
+ dput(ofs->workdir);
+ ofs->workdir = NULL;
+ sb->s_flags |= SB_RDONLY;
+ }
+
+ }
+
+ /* Show index=off in /proc/mounts for forced r/o mount */
+ if (!ofs->indexdir) {
+ ofs->config.index = false;
+ if (ofs->upper_mnt && ofs->config.nfs_export) {
+ pr_warn("overlayfs: NFS export requires an index dir, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+ }
+
+ if (ofs->config.metacopy && ofs->config.nfs_export) {
+ pr_warn("overlayfs: NFS export is not supported with metadata only copy up, falling back to nfs_export=off.\n");
+ ofs->config.nfs_export = false;
+ }
+
+ if (ofs->config.nfs_export)
+ sb->s_export_op = &ovl_export_operations;
+
+ /* Never override disk quota limits or use reserved space */
+ cap_lower(cred->cap_effective, CAP_SYS_RESOURCE);
+
+ sb->s_magic = OVERLAYFS_SUPER_MAGIC;
+ sb->s_op = &ovl_super_operations;
+ sb->s_xattr = ovl_xattr_handlers;
+ sb->s_fs_info = ofs;
+ sb->s_flags |= SB_POSIXACL;
+
+ err = -ENOMEM;
+ root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR, 0));
+ if (!root_dentry)
+ goto out_free_oe;
+
+ root_dentry->d_fsdata = oe;
+
+ mntput(upperpath.mnt);
+ if (upperpath.dentry) {
+ ovl_dentry_set_upper_alias(root_dentry);
+ if (ovl_is_impuredir(upperpath.dentry))
+ ovl_set_flag(OVL_IMPURE, d_inode(root_dentry));
+ }
+
+ /* Root is always merge -> can have whiteouts */
+ ovl_set_flag(OVL_WHITEOUTS, d_inode(root_dentry));
+ ovl_dentry_set_flag(OVL_E_CONNECTED, root_dentry);
+ ovl_set_upperdata(d_inode(root_dentry));
+ ovl_inode_init(d_inode(root_dentry), upperpath.dentry,
+ ovl_dentry_lower(root_dentry), NULL);
+
+ sb->s_root = root_dentry;
+
+ return 0;
+
+out_free_oe:
+ ovl_entry_stack_free(oe);
+ kfree(oe);
+out_err:
+ path_put(&upperpath);
+ ovl_free_fs(ofs);
+out:
+ return err;
+}
+
+static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags,
+ const char *dev_name, void *raw_data)
+{
+ return mount_nodev(fs_type, flags, raw_data, ovl_fill_super);
+}
+
+static struct file_system_type ovl_fs_type = {
+ .owner = THIS_MODULE,
+ .name = "overlay",
+ .mount = ovl_mount,
+ .kill_sb = kill_anon_super,
+};
+MODULE_ALIAS_FS("overlay");
+
+static void ovl_inode_init_once(void *foo)
+{
+ struct ovl_inode *oi = foo;
+
+ inode_init_once(&oi->vfs_inode);
+}
+
+static int __init ovl_init(void)
+{
+ int err;
+
+ ovl_inode_cachep = kmem_cache_create("ovl_inode",
+ sizeof(struct ovl_inode), 0,
+ (SLAB_RECLAIM_ACCOUNT|
+ SLAB_MEM_SPREAD|SLAB_ACCOUNT),
+ ovl_inode_init_once);
+ if (ovl_inode_cachep == NULL)
+ return -ENOMEM;
+
+ err = register_filesystem(&ovl_fs_type);
+ if (err)
+ kmem_cache_destroy(ovl_inode_cachep);
+
+ return err;
+}
+
+static void __exit ovl_exit(void)
+{
+ unregister_filesystem(&ovl_fs_type);
+
+ /*
+ * Make sure all delayed rcu free inodes are flushed before we
+ * destroy cache.
+ */
+ rcu_barrier();
+ kmem_cache_destroy(ovl_inode_cachep);
+
+}
+
+module_init(ovl_init);
+module_exit(ovl_exit);
diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
new file mode 100644
index 0000000..ace4fe4
--- /dev/null
+++ b/fs/overlayfs/util.c
@@ -0,0 +1,918 @@
+/*
+ * Copyright (C) 2011 Novell Inc.
+ * Copyright (C) 2016 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/slab.h>
+#include <linux/cred.h>
+#include <linux/xattr.h>
+#include <linux/exportfs.h>
+#include <linux/uuid.h>
+#include <linux/namei.h>
+#include <linux/ratelimit.h>
+#include "overlayfs.h"
+
+int ovl_want_write(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ return mnt_want_write(ofs->upper_mnt);
+}
+
+void ovl_drop_write(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ mnt_drop_write(ofs->upper_mnt);
+}
+
+struct dentry *ovl_workdir(struct dentry *dentry)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+ return ofs->workdir;
+}
+
+const struct cred *ovl_override_creds(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return override_creds(ofs->creator_cred);
+}
+
+struct super_block *ovl_same_sb(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ if (!ofs->numlowerfs)
+ return ofs->upper_mnt->mnt_sb;
+ else if (ofs->numlowerfs == 1 && !ofs->upper_mnt)
+ return ofs->lower_fs[0].sb;
+ else
+ return NULL;
+}
+
+/*
+ * Check if underlying fs supports file handles and try to determine encoding
+ * type, in order to deduce maximum inode number used by fs.
+ *
+ * Return 0 if file handles are not supported.
+ * Return 1 (FILEID_INO32_GEN) if fs uses the default 32bit inode encoding.
+ * Return -1 if fs uses a non default encoding with unknown inode size.
+ */
+int ovl_can_decode_fh(struct super_block *sb)
+{
+ if (!sb->s_export_op || !sb->s_export_op->fh_to_dentry ||
+ uuid_is_null(&sb->s_uuid))
+ return 0;
+
+ return sb->s_export_op->encode_fh ? -1 : FILEID_INO32_GEN;
+}
+
+struct dentry *ovl_indexdir(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->indexdir;
+}
+
+/* Index all files on copy up. For now only enabled for NFS export */
+bool ovl_index_all(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->config.nfs_export && ofs->config.index;
+}
+
+/* Verify lower origin on lookup. For now only enabled for NFS export */
+bool ovl_verify_lower(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->config.nfs_export && ofs->config.index;
+}
+
+struct ovl_entry *ovl_alloc_entry(unsigned int numlower)
+{
+ size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
+ struct ovl_entry *oe = kzalloc(size, GFP_KERNEL);
+
+ if (oe)
+ oe->numlower = numlower;
+
+ return oe;
+}
+
+bool ovl_dentry_remote(struct dentry *dentry)
+{
+ return dentry->d_flags &
+ (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE |
+ DCACHE_OP_REAL);
+}
+
+bool ovl_dentry_weird(struct dentry *dentry)
+{
+ return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |
+ DCACHE_MANAGE_TRANSIT |
+ DCACHE_OP_HASH |
+ DCACHE_OP_COMPARE);
+}
+
+enum ovl_path_type ovl_path_type(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+ enum ovl_path_type type = 0;
+
+ if (ovl_dentry_upper(dentry)) {
+ type = __OVL_PATH_UPPER;
+
+ /*
+ * Non-dir dentry can hold lower dentry of its copy up origin.
+ */
+ if (oe->numlower) {
+ if (ovl_test_flag(OVL_CONST_INO, d_inode(dentry)))
+ type |= __OVL_PATH_ORIGIN;
+ if (d_is_dir(dentry) ||
+ !ovl_has_upperdata(d_inode(dentry)))
+ type |= __OVL_PATH_MERGE;
+ }
+ } else {
+ if (oe->numlower > 1)
+ type |= __OVL_PATH_MERGE;
+ }
+ return type;
+}
+
+void ovl_path_upper(struct dentry *dentry, struct path *path)
+{
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+ path->mnt = ofs->upper_mnt;
+ path->dentry = ovl_dentry_upper(dentry);
+}
+
+void ovl_path_lower(struct dentry *dentry, struct path *path)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe->numlower) {
+ path->mnt = oe->lowerstack[0].layer->mnt;
+ path->dentry = oe->lowerstack[0].dentry;
+ } else {
+ *path = (struct path) { };
+ }
+}
+
+void ovl_path_lowerdata(struct dentry *dentry, struct path *path)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (oe->numlower) {
+ path->mnt = oe->lowerstack[oe->numlower - 1].layer->mnt;
+ path->dentry = oe->lowerstack[oe->numlower - 1].dentry;
+ } else {
+ *path = (struct path) { };
+ }
+}
+
+enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path)
+{
+ enum ovl_path_type type = ovl_path_type(dentry);
+
+ if (!OVL_TYPE_UPPER(type))
+ ovl_path_lower(dentry, path);
+ else
+ ovl_path_upper(dentry, path);
+
+ return type;
+}
+
+struct dentry *ovl_dentry_upper(struct dentry *dentry)
+{
+ return ovl_upperdentry_dereference(OVL_I(d_inode(dentry)));
+}
+
+struct dentry *ovl_dentry_lower(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->numlower ? oe->lowerstack[0].dentry : NULL;
+}
+
+struct ovl_layer *ovl_layer_lower(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->numlower ? oe->lowerstack[0].layer : NULL;
+}
+
+/*
+ * ovl_dentry_lower() could return either a data dentry or metacopy dentry
+ * dependig on what is stored in lowerstack[0]. At times we need to find
+ * lower dentry which has data (and not metacopy dentry). This helper
+ * returns the lower data dentry.
+ */
+struct dentry *ovl_dentry_lowerdata(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ return oe->numlower ? oe->lowerstack[oe->numlower - 1].dentry : NULL;
+}
+
+struct dentry *ovl_dentry_real(struct dentry *dentry)
+{
+ return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry);
+}
+
+struct dentry *ovl_i_dentry_upper(struct inode *inode)
+{
+ return ovl_upperdentry_dereference(OVL_I(inode));
+}
+
+struct inode *ovl_inode_upper(struct inode *inode)
+{
+ struct dentry *upperdentry = ovl_i_dentry_upper(inode);
+
+ return upperdentry ? d_inode(upperdentry) : NULL;
+}
+
+struct inode *ovl_inode_lower(struct inode *inode)
+{
+ return OVL_I(inode)->lower;
+}
+
+struct inode *ovl_inode_real(struct inode *inode)
+{
+ return ovl_inode_upper(inode) ?: ovl_inode_lower(inode);
+}
+
+/* Return inode which contains lower data. Do not return metacopy */
+struct inode *ovl_inode_lowerdata(struct inode *inode)
+{
+ if (WARN_ON(!S_ISREG(inode->i_mode)))
+ return NULL;
+
+ return OVL_I(inode)->lowerdata ?: ovl_inode_lower(inode);
+}
+
+/* Return real inode which contains data. Does not return metacopy inode */
+struct inode *ovl_inode_realdata(struct inode *inode)
+{
+ struct inode *upperinode;
+
+ upperinode = ovl_inode_upper(inode);
+ if (upperinode && ovl_has_upperdata(inode))
+ return upperinode;
+
+ return ovl_inode_lowerdata(inode);
+}
+
+struct ovl_dir_cache *ovl_dir_cache(struct inode *inode)
+{
+ return OVL_I(inode)->cache;
+}
+
+void ovl_set_dir_cache(struct inode *inode, struct ovl_dir_cache *cache)
+{
+ OVL_I(inode)->cache = cache;
+}
+
+void ovl_dentry_set_flag(unsigned long flag, struct dentry *dentry)
+{
+ set_bit(flag, &OVL_E(dentry)->flags);
+}
+
+void ovl_dentry_clear_flag(unsigned long flag, struct dentry *dentry)
+{
+ clear_bit(flag, &OVL_E(dentry)->flags);
+}
+
+bool ovl_dentry_test_flag(unsigned long flag, struct dentry *dentry)
+{
+ return test_bit(flag, &OVL_E(dentry)->flags);
+}
+
+bool ovl_dentry_is_opaque(struct dentry *dentry)
+{
+ return ovl_dentry_test_flag(OVL_E_OPAQUE, dentry);
+}
+
+bool ovl_dentry_is_whiteout(struct dentry *dentry)
+{
+ return !dentry->d_inode && ovl_dentry_is_opaque(dentry);
+}
+
+void ovl_dentry_set_opaque(struct dentry *dentry)
+{
+ ovl_dentry_set_flag(OVL_E_OPAQUE, dentry);
+}
+
+/*
+ * For hard links and decoded file handles, it's possible for ovl_dentry_upper()
+ * to return positive, while there's no actual upper alias for the inode.
+ * Copy up code needs to know about the existence of the upper alias, so it
+ * can't use ovl_dentry_upper().
+ */
+bool ovl_dentry_has_upper_alias(struct dentry *dentry)
+{
+ return ovl_dentry_test_flag(OVL_E_UPPER_ALIAS, dentry);
+}
+
+void ovl_dentry_set_upper_alias(struct dentry *dentry)
+{
+ ovl_dentry_set_flag(OVL_E_UPPER_ALIAS, dentry);
+}
+
+static bool ovl_should_check_upperdata(struct inode *inode)
+{
+ if (!S_ISREG(inode->i_mode))
+ return false;
+
+ if (!ovl_inode_lower(inode))
+ return false;
+
+ return true;
+}
+
+bool ovl_has_upperdata(struct inode *inode)
+{
+ if (!ovl_should_check_upperdata(inode))
+ return true;
+
+ if (!ovl_test_flag(OVL_UPPERDATA, inode))
+ return false;
+ /*
+ * Pairs with smp_wmb() in ovl_set_upperdata(). Main user of
+ * ovl_has_upperdata() is ovl_copy_up_meta_inode_data(). Make sure
+ * if setting of OVL_UPPERDATA is visible, then effects of writes
+ * before that are visible too.
+ */
+ smp_rmb();
+ return true;
+}
+
+void ovl_set_upperdata(struct inode *inode)
+{
+ /*
+ * Pairs with smp_rmb() in ovl_has_upperdata(). Make sure
+ * if OVL_UPPERDATA flag is visible, then effects of write operations
+ * before it are visible as well.
+ */
+ smp_wmb();
+ ovl_set_flag(OVL_UPPERDATA, inode);
+}
+
+/* Caller should hold ovl_inode->lock */
+bool ovl_dentry_needs_data_copy_up_locked(struct dentry *dentry, int flags)
+{
+ if (!ovl_open_flags_need_copy_up(flags))
+ return false;
+
+ return !ovl_test_flag(OVL_UPPERDATA, d_inode(dentry));
+}
+
+bool ovl_dentry_needs_data_copy_up(struct dentry *dentry, int flags)
+{
+ if (!ovl_open_flags_need_copy_up(flags))
+ return false;
+
+ return !ovl_has_upperdata(d_inode(dentry));
+}
+
+bool ovl_redirect_dir(struct super_block *sb)
+{
+ struct ovl_fs *ofs = sb->s_fs_info;
+
+ return ofs->config.redirect_dir && !ofs->noxattr;
+}
+
+const char *ovl_dentry_get_redirect(struct dentry *dentry)
+{
+ return OVL_I(d_inode(dentry))->redirect;
+}
+
+void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect)
+{
+ struct ovl_inode *oi = OVL_I(d_inode(dentry));
+
+ kfree(oi->redirect);
+ oi->redirect = redirect;
+}
+
+void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,
+ struct dentry *lowerdentry, struct dentry *lowerdata)
+{
+ struct inode *realinode = d_inode(upperdentry ?: lowerdentry);
+
+ if (upperdentry)
+ OVL_I(inode)->__upperdentry = upperdentry;
+ if (lowerdentry)
+ OVL_I(inode)->lower = igrab(d_inode(lowerdentry));
+ if (lowerdata)
+ OVL_I(inode)->lowerdata = igrab(d_inode(lowerdata));
+
+ ovl_copyattr(realinode, inode);
+ ovl_copyflags(realinode, inode);
+ if (!inode->i_ino)
+ inode->i_ino = realinode->i_ino;
+}
+
+void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
+{
+ struct inode *upperinode = d_inode(upperdentry);
+
+ WARN_ON(OVL_I(inode)->__upperdentry);
+
+ /*
+ * Make sure upperdentry is consistent before making it visible
+ */
+ smp_wmb();
+ OVL_I(inode)->__upperdentry = upperdentry;
+ if (inode_unhashed(inode)) {
+ if (!inode->i_ino)
+ inode->i_ino = upperinode->i_ino;
+ inode->i_private = upperinode;
+ __insert_inode_hash(inode, (unsigned long) upperinode);
+ }
+}
+
+static void ovl_dentry_version_inc(struct dentry *dentry, bool impurity)
+{
+ struct inode *inode = d_inode(dentry);
+
+ WARN_ON(!inode_is_locked(inode));
+ /*
+ * Version is used by readdir code to keep cache consistent. For merge
+ * dirs all changes need to be noted. For non-merge dirs, cache only
+ * contains impure (ones which have been copied up and have origins)
+ * entries, so only need to note changes to impure entries.
+ */
+ if (OVL_TYPE_MERGE(ovl_path_type(dentry)) || impurity)
+ OVL_I(inode)->version++;
+}
+
+void ovl_dir_modified(struct dentry *dentry, bool impurity)
+{
+ /* Copy mtime/ctime */
+ ovl_copyattr(d_inode(ovl_dentry_upper(dentry)), d_inode(dentry));
+
+ ovl_dentry_version_inc(dentry, impurity);
+}
+
+u64 ovl_dentry_version_get(struct dentry *dentry)
+{
+ struct inode *inode = d_inode(dentry);
+
+ WARN_ON(!inode_is_locked(inode));
+ return OVL_I(inode)->version;
+}
+
+bool ovl_is_whiteout(struct dentry *dentry)
+{
+ struct inode *inode = dentry->d_inode;
+
+ return inode && IS_WHITEOUT(inode);
+}
+
+struct file *ovl_path_open(struct path *path, int flags)
+{
+ return dentry_open(path, flags | O_NOATIME, current_cred());
+}
+
+/* Caller should hold ovl_inode->lock */
+static bool ovl_already_copied_up_locked(struct dentry *dentry, int flags)
+{
+ bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
+
+ if (ovl_dentry_upper(dentry) &&
+ (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
+ !ovl_dentry_needs_data_copy_up_locked(dentry, flags))
+ return true;
+
+ return false;
+}
+
+bool ovl_already_copied_up(struct dentry *dentry, int flags)
+{
+ bool disconnected = dentry->d_flags & DCACHE_DISCONNECTED;
+
+ /*
+ * Check if copy-up has happened as well as for upper alias (in
+ * case of hard links) is there.
+ *
+ * Both checks are lockless:
+ * - false negatives: will recheck under oi->lock
+ * - false positives:
+ * + ovl_dentry_upper() uses memory barriers to ensure the
+ * upper dentry is up-to-date
+ * + ovl_dentry_has_upper_alias() relies on locking of
+ * upper parent i_rwsem to prevent reordering copy-up
+ * with rename.
+ */
+ if (ovl_dentry_upper(dentry) &&
+ (ovl_dentry_has_upper_alias(dentry) || disconnected) &&
+ !ovl_dentry_needs_data_copy_up(dentry, flags))
+ return true;
+
+ return false;
+}
+
+int ovl_copy_up_start(struct dentry *dentry, int flags)
+{
+ struct ovl_inode *oi = OVL_I(d_inode(dentry));
+ int err;
+
+ err = mutex_lock_interruptible(&oi->lock);
+ if (!err && ovl_already_copied_up_locked(dentry, flags)) {
+ err = 1; /* Already copied up */
+ mutex_unlock(&oi->lock);
+ }
+
+ return err;
+}
+
+void ovl_copy_up_end(struct dentry *dentry)
+{
+ mutex_unlock(&OVL_I(d_inode(dentry))->lock);
+}
+
+bool ovl_check_origin_xattr(struct dentry *dentry)
+{
+ int res;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0);
+
+ /* Zero size value means "copied up but origin unknown" */
+ if (res >= 0)
+ return true;
+
+ return false;
+}
+
+bool ovl_check_dir_xattr(struct dentry *dentry, const char *name)
+{
+ int res;
+ char val;
+
+ if (!d_is_dir(dentry))
+ return false;
+
+ res = vfs_getxattr(dentry, name, &val, 1);
+ if (res == 1 && val == 'y')
+ return true;
+
+ return false;
+}
+
+int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry,
+ const char *name, const void *value, size_t size,
+ int xerr)
+{
+ int err;
+ struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
+
+ if (ofs->noxattr)
+ return xerr;
+
+ err = ovl_do_setxattr(upperdentry, name, value, size, 0);
+
+ if (err == -EOPNOTSUPP) {
+ pr_warn("overlayfs: cannot set %s xattr on upper\n", name);
+ ofs->noxattr = true;
+ return xerr;
+ }
+
+ return err;
+}
+
+int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry)
+{
+ int err;
+
+ if (ovl_test_flag(OVL_IMPURE, d_inode(dentry)))
+ return 0;
+
+ /*
+ * Do not fail when upper doesn't support xattrs.
+ * Upper inodes won't have origin nor redirect xattr anyway.
+ */
+ err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE,
+ "y", 1, 0);
+ if (!err)
+ ovl_set_flag(OVL_IMPURE, d_inode(dentry));
+
+ return err;
+}
+
+void ovl_set_flag(unsigned long flag, struct inode *inode)
+{
+ set_bit(flag, &OVL_I(inode)->flags);
+}
+
+void ovl_clear_flag(unsigned long flag, struct inode *inode)
+{
+ clear_bit(flag, &OVL_I(inode)->flags);
+}
+
+bool ovl_test_flag(unsigned long flag, struct inode *inode)
+{
+ return test_bit(flag, &OVL_I(inode)->flags);
+}
+
+/**
+ * Caller must hold a reference to inode to prevent it from being freed while
+ * it is marked inuse.
+ */
+bool ovl_inuse_trylock(struct dentry *dentry)
+{
+ struct inode *inode = d_inode(dentry);
+ bool locked = false;
+
+ spin_lock(&inode->i_lock);
+ if (!(inode->i_state & I_OVL_INUSE)) {
+ inode->i_state |= I_OVL_INUSE;
+ locked = true;
+ }
+ spin_unlock(&inode->i_lock);
+
+ return locked;
+}
+
+void ovl_inuse_unlock(struct dentry *dentry)
+{
+ if (dentry) {
+ struct inode *inode = d_inode(dentry);
+
+ spin_lock(&inode->i_lock);
+ WARN_ON(!(inode->i_state & I_OVL_INUSE));
+ inode->i_state &= ~I_OVL_INUSE;
+ spin_unlock(&inode->i_lock);
+ }
+}
+
+/*
+ * Does this overlay dentry need to be indexed on copy up?
+ */
+bool ovl_need_index(struct dentry *dentry)
+{
+ struct dentry *lower = ovl_dentry_lower(dentry);
+
+ if (!lower || !ovl_indexdir(dentry->d_sb))
+ return false;
+
+ /* Index all files for NFS export and consistency verification */
+ if (ovl_index_all(dentry->d_sb))
+ return true;
+
+ /* Index only lower hardlinks on copy up */
+ if (!d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
+ return true;
+
+ return false;
+}
+
+/* Caller must hold OVL_I(inode)->lock */
+static void ovl_cleanup_index(struct dentry *dentry)
+{
+ struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
+ struct inode *dir = indexdir->d_inode;
+ struct dentry *lowerdentry = ovl_dentry_lower(dentry);
+ struct dentry *upperdentry = ovl_dentry_upper(dentry);
+ struct dentry *index = NULL;
+ struct inode *inode;
+ struct qstr name = { };
+ int err;
+
+ err = ovl_get_index_name(lowerdentry, &name);
+ if (err)
+ goto fail;
+
+ inode = d_inode(upperdentry);
+ if (!S_ISDIR(inode->i_mode) && inode->i_nlink != 1) {
+ pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n",
+ upperdentry, inode->i_ino, inode->i_nlink);
+ /*
+ * We either have a bug with persistent union nlink or a lower
+ * hardlink was added while overlay is mounted. Adding a lower
+ * hardlink and then unlinking all overlay hardlinks would drop
+ * overlay nlink to zero before all upper inodes are unlinked.
+ * As a safety measure, when that situation is detected, set
+ * the overlay nlink to the index inode nlink minus one for the
+ * index entry itself.
+ */
+ set_nlink(d_inode(dentry), inode->i_nlink - 1);
+ ovl_set_nlink_upper(dentry);
+ goto out;
+ }
+
+ inode_lock_nested(dir, I_MUTEX_PARENT);
+ index = lookup_one_len(name.name, indexdir, name.len);
+ err = PTR_ERR(index);
+ if (IS_ERR(index)) {
+ index = NULL;
+ } else if (ovl_index_all(dentry->d_sb)) {
+ /* Whiteout orphan index to block future open by handle */
+ err = ovl_cleanup_and_whiteout(indexdir, dir, index);
+ } else {
+ /* Cleanup orphan index entries */
+ err = ovl_cleanup(dir, index);
+ }
+
+ inode_unlock(dir);
+ if (err)
+ goto fail;
+
+out:
+ kfree(name.name);
+ dput(index);
+ return;
+
+fail:
+ pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err);
+ goto out;
+}
+
+/*
+ * Operations that change overlay inode and upper inode nlink need to be
+ * synchronized with copy up for persistent nlink accounting.
+ */
+int ovl_nlink_start(struct dentry *dentry, bool *locked)
+{
+ struct ovl_inode *oi = OVL_I(d_inode(dentry));
+ const struct cred *old_cred;
+ int err;
+
+ if (!d_inode(dentry))
+ return 0;
+
+ /*
+ * With inodes index is enabled, we store the union overlay nlink
+ * in an xattr on the index inode. When whiting out an indexed lower,
+ * we need to decrement the overlay persistent nlink, but before the
+ * first copy up, we have no upper index inode to store the xattr.
+ *
+ * As a workaround, before whiteout/rename over an indexed lower,
+ * copy up to create the upper index. Creating the upper index will
+ * initialize the overlay nlink, so it could be dropped if unlink
+ * or rename succeeds.
+ *
+ * TODO: implement metadata only index copy up when called with
+ * ovl_copy_up_flags(dentry, O_PATH).
+ */
+ if (ovl_need_index(dentry) && !ovl_dentry_has_upper_alias(dentry)) {
+ err = ovl_copy_up(dentry);
+ if (err)
+ return err;
+ }
+
+ err = mutex_lock_interruptible(&oi->lock);
+ if (err)
+ return err;
+
+ if (d_is_dir(dentry) || !ovl_test_flag(OVL_INDEX, d_inode(dentry)))
+ goto out;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ /*
+ * The overlay inode nlink should be incremented/decremented IFF the
+ * upper operation succeeds, along with nlink change of upper inode.
+ * Therefore, before link/unlink/rename, we store the union nlink
+ * value relative to the upper inode nlink in an upper inode xattr.
+ */
+ err = ovl_set_nlink_upper(dentry);
+ revert_creds(old_cred);
+
+out:
+ if (err)
+ mutex_unlock(&oi->lock);
+ else
+ *locked = true;
+
+ return err;
+}
+
+void ovl_nlink_end(struct dentry *dentry, bool locked)
+{
+ if (locked) {
+ if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
+ d_inode(dentry)->i_nlink == 0) {
+ const struct cred *old_cred;
+
+ old_cred = ovl_override_creds(dentry->d_sb);
+ ovl_cleanup_index(dentry);
+ revert_creds(old_cred);
+ }
+
+ mutex_unlock(&OVL_I(d_inode(dentry))->lock);
+ }
+}
+
+int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
+{
+ /* Workdir should not be the same as upperdir */
+ if (workdir == upperdir)
+ goto err;
+
+ /* Workdir should not be subdir of upperdir and vice versa */
+ if (lock_rename(workdir, upperdir) != NULL)
+ goto err_unlock;
+
+ return 0;
+
+err_unlock:
+ unlock_rename(workdir, upperdir);
+err:
+ pr_err("overlayfs: failed to lock workdir+upperdir\n");
+ return -EIO;
+}
+
+/* err < 0, 0 if no metacopy xattr, 1 if metacopy xattr found */
+int ovl_check_metacopy_xattr(struct dentry *dentry)
+{
+ int res;
+
+ /* Only regular files can have metacopy xattr */
+ if (!S_ISREG(d_inode(dentry)->i_mode))
+ return 0;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_METACOPY, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return 0;
+ goto out;
+ }
+
+ return 1;
+out:
+ pr_warn_ratelimited("overlayfs: failed to get metacopy (%i)\n", res);
+ return res;
+}
+
+bool ovl_is_metacopy_dentry(struct dentry *dentry)
+{
+ struct ovl_entry *oe = dentry->d_fsdata;
+
+ if (!d_is_reg(dentry))
+ return false;
+
+ if (ovl_dentry_upper(dentry)) {
+ if (!ovl_has_upperdata(d_inode(dentry)))
+ return true;
+ return false;
+ }
+
+ return (oe->numlower > 1);
+}
+
+char *ovl_get_redirect_xattr(struct dentry *dentry, int padding)
+{
+ int res;
+ char *s, *next, *buf = NULL;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0);
+ if (res < 0) {
+ if (res == -ENODATA || res == -EOPNOTSUPP)
+ return NULL;
+ goto fail;
+ }
+
+ buf = kzalloc(res + padding + 1, GFP_KERNEL);
+ if (!buf)
+ return ERR_PTR(-ENOMEM);
+
+ if (res == 0)
+ goto invalid;
+
+ res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res);
+ if (res < 0)
+ goto fail;
+ if (res == 0)
+ goto invalid;
+
+ if (buf[0] == '/') {
+ for (s = buf; *s++ == '/'; s = next) {
+ next = strchrnul(s, '/');
+ if (s == next)
+ goto invalid;
+ }
+ } else {
+ if (strchr(buf, '/') != NULL)
+ goto invalid;
+ }
+
+ return buf;
+
+err_free:
+ kfree(buf);
+ return ERR_PTR(res);
+fail:
+ pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res);
+ goto err_free;
+invalid:
+ pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf);
+ res = -EINVAL;
+ goto err_free;
+}