Commit db8fe64f authored by Josef Bacik's avatar Josef Bacik Committed by David Sterba
Browse files

btrfs: handle error in btrfs_cache_block_group 



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: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent f72ff01d

fs/btrfs/extent-tree.c

+18 −2
Original line number Diff line number Diff line
@@ -3799,6 +3799,7 @@ 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 *block_group = NULL;

	struct find_free_extent_ctl ffe_ctl = {0};
@@ -3958,7 +3959,20 @@ have_block_group: 
		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;

		}
@@ -4045,7 +4059,7 @@ loop: 
	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.
@@ -4056,6 +4070,8 @@ loop: 
		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;

}

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