btrfs: output extra debug info if we failed to find an inline backref

[BUG]
Syzbot reported several warning triggered inside
lookup_inline_extent_backref().

[CAUSE]
As usual, the reproducer doesn't reliably trigger locally here, but at
least we know the WARN_ON() is triggered when an inline backref can not
be found, and it can only be triggered when @insert is true. (I.e.
inserting a new inline backref, which means the backref should already
exist)

[ENHANCEMENT]
After the WARN_ON(), dump all the parameters and the extent tree
leaf to help debug.

Link: https://syzkaller.appspot.com/bug?extid=d6f9ff86c1d804ba2bc6
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index e0508114f0bd339a2cc558319fe1cbddea7ad781..105f528382e750592a6374fd846baa30bef7fd37 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -848,6 +848,11 @@ again:
                err = -ENOENT;
                goto out;
        } else if (WARN_ON(ret)) {
+               btrfs_print_leaf(path->nodes[0]);
+               btrfs_err(fs_info,
+"extent item not found for insert, bytenr %llu num_bytes %llu parent %llu root_objectid %llu owner %llu offset %llu",
+                         bytenr, num_bytes, parent, root_objectid, owner,
+                         offset);
                err = -EIO;
                goto out;
        }