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btrfs: zoned: properly take lock to read/update block group's zoned variables

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__btrfs_add_free_space_zoned() references and modifies bg's alloc_offset,
ro, and zone_unusable, but without taking the lock. It is mostly safe
because they monotonically increase (at least for now) and this function is
mostly called by a transaction commit, which is serialized by itself.

Still, taking the lock is a safer and correct option and I'm going to add a
change to reset zone_unusable while a block group is still alive. So, add
locking around the operations.

Fixes: 169e0da91a ("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>
This commit is contained in:
Naohiro Aota 2024-08-01 16:47:52 +09:00 committed by David Sterba
parent 008e2512dc
commit e30729d4bd
1 changed files with 8 additions and 6 deletions
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14
fs/btrfs/free-space-cache.c
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@ -2697,15 +2697,16 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group,
u64 offset = bytenr - block_group->start;
u64 to_free, to_unusable;
int bg_reclaim_threshold = 0;
bool initial = ((size == block_group->length) && (block_group->alloc_offset == 0));
bool initial;
u64 reclaimable_unusable;
WARN_ON(!initial && offset + size > block_group->zone_capacity);
spin_lock(&block_group->lock);
initial = ((size == block_group->length) && (block_group->alloc_offset == 0));
WARN_ON(!initial && offset + size > block_group->zone_capacity);
if (!initial)
bg_reclaim_threshold = READ_ONCE(sinfo->bg_reclaim_threshold);
spin_lock(&ctl->tree_lock);
if (!used)
to_free = size;
else if (initial)
@ -2718,7 +2719,9 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group,
to_free = offset + size - block_group->alloc_offset;
to_unusable = size - to_free;
spin_lock(&ctl->tree_lock);
ctl->free_space += to_free;
spin_unlock(&ctl->tree_lock);
/*
* If the block group is read-only, we should account freed space into
* bytes_readonly.
@ -2727,11 +2730,8 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group,
block_group->zone_unusable += to_unusable;
WARN_ON(block_group->zone_unusable > block_group->length);
}
spin_unlock(&ctl->tree_lock);
if (!used) {
spin_lock(&block_group->lock);
block_group->alloc_offset -= size;
spin_unlock(&block_group->lock);
}
reclaimable_unusable = block_group->zone_unusable -
@ -2745,6 +2745,8 @@ static int __btrfs_add_free_space_zoned(struct btrfs_block_group *block_group,
btrfs_mark_bg_to_reclaim(block_group);
}
spin_unlock(&block_group->lock);
return 0;
}