fs: btrfs: Implement btrfs_lookup_path()

This is the extent buffer based path lookup routine.

To implement this, btrfs_lookup_dir_item() is crossported from
btrfs-progs, and implements btrfs_lookup_path() from scratch.

Unlike the existing __btrfs_lookup_path(), since btrfs_read_fs_root()
will check whether a root is a orphan at read time, there is no need to
check root backref, this makes the code a little easier to read.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index d635b0814e..111a5a6a29 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1285,6 +1285,10 @@ struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
 					     struct btrfs_path *path, u64 dir,
 					     const char *name, int name_len,
 					     int mod);
+/* inode.c */
+int btrfs_lookup_path(struct btrfs_root *root, u64 ino, const char *filename,
+			struct btrfs_root **root_ret, u64 *ino_ret,
+			u8 *type_ret, int symlink_limit);
 
 /* ctree.c */
 int btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2);