Btrfs: fix regression in scrub path resolving

In commit 4692cf58 we introduced new backref walking code for btrfs. This
assumes we're searching live roots, which requires a transaction context.
While scrubbing, however, we must not join a transaction because this could
deadlock with the commit path. Additionally, what scrub really wants to do
is resolving a logical address in the commit root it's currently checking.

This patch adds support for logical to path resolving on commit roots and
makes scrub use that.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

1 files changed, 3 insertions, 2 deletions

diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
index d00dfa9ca934..57ea2e959e4d 100644
--- a/fs/btrfs/backref.h
+++ b/fs/btrfs/backref.h
@@ -22,6 +22,8 @@
 #include "ioctl.h"
 #include "ulist.h"
 
+#define BTRFS_BACKREF_SEARCH_COMMIT_ROOT ((struct btrfs_trans_handle *)0)
+
 struct inode_fs_paths {
         struct btrfs_path               *btrfs_path;
         struct btrfs_root               *fs_root;
@@ -44,9 +46,8 @@ int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
                                 u64 *out_root, u8 *out_level);
 
 int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
-                                struct btrfs_path *path,
                                 u64 extent_item_objectid,
-                                u64 extent_offset,
+                                u64 extent_offset, int search_commit_root,
                                 iterate_extent_inodes_t *iterate, void *ctx);
 
 int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,