diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index 618ba7670e66d..18305f5c74c93 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1824,10 +1824,24 @@ void btrfs_reclaim_bgs_work(struct work_struct *work)
 
 next:
 		btrfs_put_block_group(bg);
+
+		mutex_unlock(&fs_info->reclaim_bgs_lock);
+		/*
+		 * Reclaiming all the block groups in the list can take really
+		 * long.  Prioritize cleaning up unused block groups.
+		 */
+		btrfs_delete_unused_bgs(fs_info);
+		/*
+		 * If we are interrupted by a balance, we can just bail out. The
+		 * cleaner thread restart again if necessary.
+		 */
+		if (!mutex_trylock(&fs_info->reclaim_bgs_lock))
+			goto end;
 		spin_lock(&fs_info->unused_bgs_lock);
 	}
 	spin_unlock(&fs_info->unused_bgs_lock);
 	mutex_unlock(&fs_info->reclaim_bgs_lock);
+end:
 	btrfs_exclop_finish(fs_info);
 	sb_end_write(fs_info->sb);
 }