v4.19.13 snapshot.
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,
+};