bcachefs: Fix missing memalloc_nofs_restore()

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/btree_cache.c

@@ -329,9 +329,9 @@ static unsigned long bch2_btree_cache_scan(struct shrinker *shrink,
 			clear_btree_node_accessed(b);
 	}
 
-	memalloc_nofs_restore(flags);
 	mutex_unlock(&bc->lock);
 out:
+	memalloc_nofs_restore(flags);
 	return (unsigned long) freed * btree_pages(c);
 }