From: Josef Bacik josef@toxicpanda.com

[ Upstream commit 6a4730b325aaa48f7a5d5ba97aff0a955e2d9cec ]

This BUG_ON is meant to catch backref cache problems, but these can arise from either bugs in the backref cache or corruption in the extent tree. Fix it to be a proper error.

Reviewed-by: Boris Burkov boris@bur.io Signed-off-by: Josef Bacik josef@toxicpanda.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/relocation.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 98e3b3749ec12..5b921e6ed94e2 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -3976,8 +3976,18 @@ int btrfs_reloc_cow_block(struct btrfs_trans_handle *trans, WARN_ON(!first_cow && level == 0);

node = rc->backref_cache.path[level]; - BUG_ON(node->bytenr != buf->start && - node->new_bytenr != buf->start); + + /* + * If node->bytenr != buf->start and node->new_bytenr != + * buf->start then we've got the wrong backref node for what we + * expected to see here and the cache is incorrect. + */ + if (unlikely(node->bytenr != buf->start && node->new_bytenr != buf->start)) { + btrfs_err(fs_info, +"bytenr %llu was found but our backref cache was expecting %llu or %llu", + buf->start, node->bytenr, node->new_bytenr); + return -EUCLEAN; + }

btrfs_backref_drop_node_buffer(node); atomic_inc(&cow->refs);