btrfs: Replace fs_info->submit_workers with btrfs_workqueue.

Much like the fs_info->workers, replace the fs_info->submit_workers
use the same btrfs_workqueue.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Tested-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fb.com>
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index be00199..9ed559e 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -1326,7 +1326,7 @@
 	btrfs_set_max_workers(&fs_info->generic_worker, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
 	btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
-	btrfs_set_max_workers(&fs_info->submit_workers, new_pool_size);
+	btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
 	btrfs_set_max_workers(&fs_info->caching_workers, new_pool_size);
 	btrfs_set_max_workers(&fs_info->fixup_workers, new_pool_size);
 	btrfs_set_max_workers(&fs_info->endio_workers, new_pool_size);