Btrfs: new backref walking code

The old backref iteration code could only safely be used on commit roots.
Besides this limitation, it had bugs in finding the roots for these
references. This commit replaces large parts of it by btrfs_find_all_roots()
which a) really finds all roots and the correct roots, b) works correctly
under heavy file system load, c) considers delayed refs.

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

1 files changed, 4 insertions, 3 deletions

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index c27bcb67f330..b5edff25a53f 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -309,7 +309,7 @@ static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
         u8 ref_level;
         unsigned long ptr = 0;
         const int bufsize = 4096;
-        u64 extent_offset;
+        u64 extent_item_pos;
 
         path = btrfs_alloc_path();
 
@@ -329,12 +329,13 @@ static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
         if (ret < 0)
                 goto out;
 
-        extent_offset = swarn.logical - found_key.objectid;
+        extent_item_pos = swarn.logical - found_key.objectid;
         swarn.extent_item_size = found_key.offset;
 
         eb = path->nodes[0];
         ei = btrfs_item_ptr(eb, path->slots[0], struct btrfs_extent_item);
         item_size = btrfs_item_size_nr(eb, path->slots[0]);
+        btrfs_release_path(path);
 
         if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
                 do {
@@ -351,7 +352,7 @@ static void scrub_print_warning(const char *errstr, struct scrub_bio *sbio,
         } else {
                 swarn.path = path;
                 iterate_extent_inodes(fs_info, path, found_key.objectid,
-                                        extent_offset,
+                                        extent_item_pos,
                                         scrub_print_warning_inode, &swarn);
         }