6.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Naohiro Aota naohiro.aota@wdc.com
commit bf9821ba4792a0d9a2e72803ae7b4341faf3d532 upstream.
When btrfs reserves an extent and does not use it (e.g, by an error), it calls btrfs_free_reserved_extent() to free the reserved extent. In the process, it calls btrfs_add_free_space() and then it accounts the region bytes as block_group->zone_unusable.
However, it leaves the space_info->bytes_zone_unusable side not updated. As a result, ENOSPC can happen while a space_info reservation succeeded. The reservation is fine because the freed region is not added in space_info->bytes_zone_unusable, leaving that space as "free". OTOH, corresponding block group counts it as zone_unusable and its allocation pointer is not rewound, we cannot allocate an extent from that block group. That will also negate space_info's async/sync reclaim process, and cause an ENOSPC error from the extent allocation process.
Fix that by returning the space to space_info->bytes_zone_unusable. Ideally, since a bio is not submitted for this reserved region, we should return the space to free space and rewind the allocation pointer. But, it needs rework on extent allocation handling, so let it work in this way for now.
Fixes: 169e0da91a21 ("btrfs: zoned: track unusable bytes for zones") CC: stable@vger.kernel.org # 5.15+ Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/block-group.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -3819,6 +3819,8 @@ void btrfs_free_reserved_bytes(struct bt spin_lock(&cache->lock); if (cache->ro) space_info->bytes_readonly += num_bytes; + else if (btrfs_is_zoned(cache->fs_info)) + space_info->bytes_zone_unusable += num_bytes; cache->reserved -= num_bytes; space_info->bytes_reserved -= num_bytes; space_info->max_extent_size = 0;