v4.19.13 snapshot.
diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
new file mode 100644
index 0000000..1f3755b
--- /dev/null
+++ b/fs/btrfs/export.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/fs.h>
+#include <linux/types.h>
+#include "ctree.h"
+#include "disk-io.h"
+#include "btrfs_inode.h"
+#include "print-tree.h"
+#include "export.h"
+
+#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
+ parent_objectid) / 4)
+#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
+ parent_root_objectid) / 4)
+#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
+
+static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
+ struct inode *parent)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *)fh;
+ int len = *max_len;
+ int type;
+
+ if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
+ *max_len = BTRFS_FID_SIZE_CONNECTABLE;
+ return FILEID_INVALID;
+ } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
+ *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
+ return FILEID_INVALID;
+ }
+
+ len = BTRFS_FID_SIZE_NON_CONNECTABLE;
+ type = FILEID_BTRFS_WITHOUT_PARENT;
+
+ fid->objectid = btrfs_ino(BTRFS_I(inode));
+ fid->root_objectid = BTRFS_I(inode)->root->objectid;
+ fid->gen = inode->i_generation;
+
+ if (parent) {
+ u64 parent_root_id;
+
+ fid->parent_objectid = BTRFS_I(parent)->location.objectid;
+ fid->parent_gen = parent->i_generation;
+ parent_root_id = BTRFS_I(parent)->root->objectid;
+
+ if (parent_root_id != fid->root_objectid) {
+ fid->parent_root_objectid = parent_root_id;
+ len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
+ type = FILEID_BTRFS_WITH_PARENT_ROOT;
+ } else {
+ len = BTRFS_FID_SIZE_CONNECTABLE;
+ type = FILEID_BTRFS_WITH_PARENT;
+ }
+ }
+
+ *max_len = len;
+ return type;
+}
+
+static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
+ u64 root_objectid, u32 generation,
+ int check_generation)
+{
+ struct btrfs_fs_info *fs_info = btrfs_sb(sb);
+ struct btrfs_root *root;
+ struct inode *inode;
+ struct btrfs_key key;
+ int index;
+ int err = 0;
+
+ if (objectid < BTRFS_FIRST_FREE_OBJECTID)
+ return ERR_PTR(-ESTALE);
+
+ key.objectid = root_objectid;
+ key.type = BTRFS_ROOT_ITEM_KEY;
+ key.offset = (u64)-1;
+
+ index = srcu_read_lock(&fs_info->subvol_srcu);
+
+ root = btrfs_read_fs_root_no_name(fs_info, &key);
+ if (IS_ERR(root)) {
+ err = PTR_ERR(root);
+ goto fail;
+ }
+
+ key.objectid = objectid;
+ key.type = BTRFS_INODE_ITEM_KEY;
+ key.offset = 0;
+
+ inode = btrfs_iget(sb, &key, root, NULL);
+ if (IS_ERR(inode)) {
+ err = PTR_ERR(inode);
+ goto fail;
+ }
+
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
+
+ if (check_generation && generation != inode->i_generation) {
+ iput(inode);
+ return ERR_PTR(-ESTALE);
+ }
+
+ return d_obtain_alias(inode);
+fail:
+ srcu_read_unlock(&fs_info->subvol_srcu, index);
+ return ERR_PTR(err);
+}
+
+static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
+ int fh_len, int fh_type)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *) fh;
+ u64 objectid, root_objectid;
+ u32 generation;
+
+ if (fh_type == FILEID_BTRFS_WITH_PARENT) {
+ if (fh_len < BTRFS_FID_SIZE_CONNECTABLE)
+ return NULL;
+ root_objectid = fid->root_objectid;
+ } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
+ if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
+ return NULL;
+ root_objectid = fid->parent_root_objectid;
+ } else
+ return NULL;
+
+ objectid = fid->parent_objectid;
+ generation = fid->parent_gen;
+
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
+}
+
+static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
+ int fh_len, int fh_type)
+{
+ struct btrfs_fid *fid = (struct btrfs_fid *) fh;
+ u64 objectid, root_objectid;
+ u32 generation;
+
+ if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
+ fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
+ (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
+ fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
+ (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
+ fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
+ return NULL;
+
+ objectid = fid->objectid;
+ root_objectid = fid->root_objectid;
+ generation = fid->gen;
+
+ return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
+}
+
+static struct dentry *btrfs_get_parent(struct dentry *child)
+{
+ struct inode *dir = d_inode(child);
+ struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct btrfs_path *path;
+ struct extent_buffer *leaf;
+ struct btrfs_root_ref *ref;
+ struct btrfs_key key;
+ struct btrfs_key found_key;
+ int ret;
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return ERR_PTR(-ENOMEM);
+
+ if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
+ key.objectid = root->root_key.objectid;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = (u64)-1;
+ root = fs_info->tree_root;
+ } else {
+ key.objectid = btrfs_ino(BTRFS_I(dir));
+ key.type = BTRFS_INODE_REF_KEY;
+ key.offset = (u64)-1;
+ }
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0)
+ goto fail;
+
+ BUG_ON(ret == 0); /* Key with offset of -1 found */
+ if (path->slots[0] == 0) {
+ ret = -ENOENT;
+ goto fail;
+ }
+
+ path->slots[0]--;
+ leaf = path->nodes[0];
+
+ btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
+ if (found_key.objectid != key.objectid || found_key.type != key.type) {
+ ret = -ENOENT;
+ goto fail;
+ }
+
+ if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
+ ref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_root_ref);
+ key.objectid = btrfs_root_ref_dirid(leaf, ref);
+ } else {
+ key.objectid = found_key.offset;
+ }
+ btrfs_free_path(path);
+
+ if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
+ return btrfs_get_dentry(fs_info->sb, key.objectid,
+ found_key.offset, 0, 0);
+ }
+
+ key.type = BTRFS_INODE_ITEM_KEY;
+ key.offset = 0;
+ return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root, NULL));
+fail:
+ btrfs_free_path(path);
+ return ERR_PTR(ret);
+}
+
+static int btrfs_get_name(struct dentry *parent, char *name,
+ struct dentry *child)
+{
+ struct inode *inode = d_inode(child);
+ struct inode *dir = d_inode(parent);
+ struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
+ struct btrfs_path *path;
+ struct btrfs_root *root = BTRFS_I(dir)->root;
+ struct btrfs_inode_ref *iref;
+ struct btrfs_root_ref *rref;
+ struct extent_buffer *leaf;
+ unsigned long name_ptr;
+ struct btrfs_key key;
+ int name_len;
+ int ret;
+ u64 ino;
+
+ if (!S_ISDIR(dir->i_mode))
+ return -EINVAL;
+
+ ino = btrfs_ino(BTRFS_I(inode));
+
+ path = btrfs_alloc_path();
+ if (!path)
+ return -ENOMEM;
+ path->leave_spinning = 1;
+
+ if (ino == BTRFS_FIRST_FREE_OBJECTID) {
+ key.objectid = BTRFS_I(inode)->root->root_key.objectid;
+ key.type = BTRFS_ROOT_BACKREF_KEY;
+ key.offset = (u64)-1;
+ root = fs_info->tree_root;
+ } else {
+ key.objectid = ino;
+ key.offset = btrfs_ino(BTRFS_I(dir));
+ key.type = BTRFS_INODE_REF_KEY;
+ }
+
+ ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+ if (ret < 0) {
+ btrfs_free_path(path);
+ return ret;
+ } else if (ret > 0) {
+ if (ino == BTRFS_FIRST_FREE_OBJECTID) {
+ path->slots[0]--;
+ } else {
+ btrfs_free_path(path);
+ return -ENOENT;
+ }
+ }
+ leaf = path->nodes[0];
+
+ if (ino == BTRFS_FIRST_FREE_OBJECTID) {
+ rref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_root_ref);
+ name_ptr = (unsigned long)(rref + 1);
+ name_len = btrfs_root_ref_name_len(leaf, rref);
+ } else {
+ iref = btrfs_item_ptr(leaf, path->slots[0],
+ struct btrfs_inode_ref);
+ name_ptr = (unsigned long)(iref + 1);
+ name_len = btrfs_inode_ref_name_len(leaf, iref);
+ }
+
+ read_extent_buffer(leaf, name, name_ptr, name_len);
+ btrfs_free_path(path);
+
+ /*
+ * have to add the null termination to make sure that reconnect_path
+ * gets the right len for strlen
+ */
+ name[name_len] = '\0';
+
+ return 0;
+}
+
+const struct export_operations btrfs_export_ops = {
+ .encode_fh = btrfs_encode_fh,
+ .fh_to_dentry = btrfs_fh_to_dentry,
+ .fh_to_parent = btrfs_fh_to_parent,
+ .get_parent = btrfs_get_parent,
+ .get_name = btrfs_get_name,
+};