[PATCH AUTOSEL 5.15 2/3] btrfs: output extra debug info if we failed to find an inline backref

Sasha Levin
2023-09-07T16:00:35Z

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 7f72f50547b7af4ddf985b07fc56600a4deba281 ]

[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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/extent-tree.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 597cc2607481c..48f2de789b755 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -860,6 +860,11 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
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;
}
--
2.40.1