btrfs: reduce block group critical section in btrfs_free_reserved_bytes()

There's no need to update the space_info fields (bytes_reserved,
max_extent_size, bytes_readonly, bytes_zone_unusable) while holding the
block group's spinlock. So move those updates to happen after we unlock
the block group (and while holding the space_info locked of course), so
that all we do under the block group's critical section is to update the
block group itself.

Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 9 insertions, 6 deletions

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index ebd4c514c2c8..856bda9c99d9 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -3858,21 +3858,24 @@ void btrfs_free_reserved_bytes(struct btrfs_block_group *cache, u64 num_bytes,
 			       bool is_delalloc)
 {
 	struct btrfs_space_info *space_info = cache->space_info;
+	bool bg_ro;
 
 	spin_lock(&space_info->lock);
 	spin_lock(&cache->lock);
-	if (cache->ro)
+	bg_ro = cache->ro;
+	cache->reserved -= num_bytes;
+	if (is_delalloc)
+		cache->delalloc_bytes -= num_bytes;
+	spin_unlock(&cache->lock);
+
+	if (bg_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;
 
-	if (is_delalloc)
-		cache->delalloc_bytes -= num_bytes;
-	spin_unlock(&cache->lock);
-
 	btrfs_try_granting_tickets(space_info);
 	spin_unlock(&space_info->lock);
 }