From: Naohiro Aota naohiro.aota@wdc.com
commit f9f28e5bd0baee9708c9011897196f06ae3a2733 upstream.
Consider we have a using block group on zoned btrfs.
|<- ZU ->|<- used ->|<---free--->| `- Alloc offset ZU: Zone unusable
Marking the block group read-only will migrate the zone unusable bytes to the read-only bytes. So, we will have this.
|<- RO ->|<- used ->|<--- RO --->|
RO: Read only
When marking it back to read-write, btrfs_dec_block_group_ro() subtracts the above "RO" bytes from the space_info->bytes_readonly. And, it moves the zone unusable bytes back and again subtracts those bytes from the space_info->bytes_readonly, leading to negative bytes_readonly.
This can be observed in the output as eg.:
Data, single: total=512.00MiB, used=165.21MiB, zone_unusable=16.00EiB Data, single: total=536870912, used=173256704, zone_unusable=18446744073603186688
This commit fixes the issue by reordering the operations.
Link: https://github.com/naota/linux/issues/37 Reported-by: David Sterba dsterba@suse.com Fixes: 169e0da91a21 ("btrfs: zoned: track unusable bytes for zones") CC: stable@vger.kernel.org # 5.12+ Reviewed-by: Johannes Thumshirn johannes.thumshirn@wdc.com Signed-off-by: Naohiro Aota naohiro.aota@wdc.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/block-group.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/fs/btrfs/block-group.c +++ b/fs/btrfs/block-group.c @@ -2347,16 +2347,16 @@ void btrfs_dec_block_group_ro(struct btr spin_lock(&sinfo->lock); spin_lock(&cache->lock); if (!--cache->ro) { - num_bytes = cache->length - cache->reserved - - cache->pinned - cache->bytes_super - - cache->zone_unusable - cache->used; - sinfo->bytes_readonly -= num_bytes; if (btrfs_is_zoned(cache->fs_info)) { /* Migrate zone_unusable bytes back */ cache->zone_unusable = cache->alloc_offset - cache->used; sinfo->bytes_zone_unusable += cache->zone_unusable; sinfo->bytes_readonly -= cache->zone_unusable; } + num_bytes = cache->length - cache->reserved - + cache->pinned - cache->bytes_super - + cache->zone_unusable - cache->used; + sinfo->bytes_readonly -= num_bytes; list_del_init(&cache->ro_list); } spin_unlock(&cache->lock);