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 commit fixes the issue by reordering the operations.
Link: https://github.com/naota/linux/issues/37
Fixes: 169e0da91a21 ("btrfs: zoned: track unusable bytes for zones")
Cc: stable@xxxxxxxxxxxxxxx # 5.12+
Signed-off-by: Naohiro Aota <naohiro.aota@xxxxxxx>
---
fs/btrfs/block-group.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 38885b29e6e5..c42b6528552f 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -2442,16 +2442,16 @@ void btrfs_dec_block_group_ro(struct btrfs_block_group *cache)
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);
--
2.32.0
