From: Josef Bacik josef@toxicpanda.com
[ Upstream commit db8fe64f9ce61d1d89d3c3c34d111a43afb9f053 ]
We have a BUG_ON(ret < 0) in find_free_extent from btrfs_cache_block_group. If we fail to allocate our ctl we'll just panic, which is not good. Instead just go on to another block group. If we fail to find a block group we don't want to return ENOSPC, because really we got a ENOMEM and that's the root of the problem. Save our return from btrfs_cache_block_group(), and then if we still fail to make our allocation return that ret so we get the right error back.
Tested with inject-error.py from bcc.
Reviewed-by: Johannes Thumshirn jthumshirn@suse.de 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/extent-tree.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index 49cb26fa7c63..9ee6a6e55e4e 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -3780,6 +3780,7 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, u64 flags, int delalloc) { int ret = 0; + int cache_block_group_error = 0; struct btrfs_free_cluster *last_ptr = NULL; struct btrfs_block_group_cache *block_group = NULL; struct find_free_extent_ctl ffe_ctl = {0}; @@ -3939,7 +3940,20 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, if (unlikely(!ffe_ctl.cached)) { ffe_ctl.have_caching_bg = true; ret = btrfs_cache_block_group(block_group, 0); - BUG_ON(ret < 0); + + /* + * If we get ENOMEM here or something else we want to + * try other block groups, because it may not be fatal. + * However if we can't find anything else we need to + * save our return here so that we return the actual + * error that caused problems, not ENOSPC. + */ + if (ret < 0) { + if (!cache_block_group_error) + cache_block_group_error = ret; + ret = 0; + goto loop; + } ret = 0; }
@@ -4026,7 +4040,7 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, if (ret > 0) goto search;
- if (ret == -ENOSPC) { + if (ret == -ENOSPC && !cache_block_group_error) { /* * Use ffe_ctl->total_free_space as fallback if we can't find * any contiguous hole. @@ -4037,6 +4051,8 @@ static noinline int find_free_extent(struct btrfs_fs_info *fs_info, space_info->max_extent_size = ffe_ctl.max_extent_size; spin_unlock(&space_info->lock); ins->offset = ffe_ctl.max_extent_size; + } else if (ret == -ENOSPC) { + ret = cache_block_group_error; } return ret; }