btrfs: expand btrfs_find_item() to include find_root_ref functionality

This patch is the second step in bootstrapping the btrfs_find_item
interface. The btrfs_find_root_ref() is similar to the former
__inode_info(); it accepts four of its parameters, and duplicates the
first half of its functionality.

Replace the one former call to btrfs_find_root_ref() with a call to
btrfs_find_item(), along with the defined key type that was used
internally by btrfs_find_root ref, and a null found key. In
btrfs_find_item(), add a test for the null key at the place where
the functionality of btrfs_find_root_ref() ends; btrfs_find_item()
then returns if the test passes. Finally, remove btrfs_find_root_ref().

Signed-off-by: Kelley Nielsen <kelleynnn@gmail.com>
Suggested-by: Zach Brown <zab@redhat.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 141c15ca294e..64b87894460b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -2464,7 +2464,13 @@ static int key_search(struct extent_buffer *b, struct btrfs_key *key,
 /* Proposed generic search function, meant to take the place of the
 * various small search helper functions throughout the code and standardize
 * the search interface. Right now, it only replaces the former __inode_info
-* in backref.c.
+* in backref.c, and the former btrfs_find_root_ref in root-tree.c.
+*
+* If a null key is passed, it returns immediately after running
+* btrfs_search_slot, leaving the path filled as it is and passing its
+* return value upward. If a real key is passed, it will set the caller's
+* path to point to the first item in the tree after its specified
+* objectid, type, and offset for which objectid and type match the input.
 */
 int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
                 u64 iobjectid, u64 ioff, u8 key_type,
@@ -2479,7 +2485,7 @@ int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
         key.offset = ioff;
 
         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
-        if (ret < 0)
+        if ((ret < 0) || (found_key == NULL))
                 return ret;
 
         eb = path->nodes[0];