[PATCH 5.17 0177/1126] btrfs: extend locking to all space_info members accesses

Greg Kroah-Hartman
2022-04-05T08:01:26Z

From: Niels Dossche <dossche.niels@gmail.com>

commit 06bae876634ebf837ba70ea3de532b288326103d upstream.

bytes_pinned is always accessed under space_info->lock, except in
btrfs_preempt_reclaim_metadata_space, however the other members are
accessed under that lock. The reserved member of the rsv's are also
partially accessed under a lock and partially not. Move all these
accesses into the same lock to ensure consistency.

This could potentially race and lead to a flush instead of a commit but
it's not a big problem as it's only for preemptive flush.

CC: stable@vger.kernel.org # 5.15+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Niels Dossche <niels.dossche@ugent.be>
Signed-off-by: Niels Dossche <dossche.niels@gmail.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/space-info.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/btrfs/space-info.c
+++ b/fs/btrfs/space-info.c
@@ -1061,7 +1061,6 @@ static void btrfs_preempt_reclaim_metada
trans_rsv->reserved;
if (block_rsv_size < space_info->bytes_may_use)
delalloc_size = space_info->bytes_may_use - block_rsv_size;
- spin_unlock(&space_info->lock);

/*
* We don't want to include the global_rsv in our calculation,
@@ -1092,6 +1091,8 @@ static void btrfs_preempt_reclaim_metada
flush = FLUSH_DELAYED_REFS_NR;
}

+ spin_unlock(&space_info->lock);
+
/*
* We don't want to reclaim everything, just a portion, so scale
* down the to_reclaim by 1/4. If it takes us down to 0,