fsnotify: replace igrab() with ihold() on attach connector

We must have a reference on inode, so ihold is cheaper.

Link: https://lore.kernel.org/r/20210810151220.285179-2-amir73il@gmail.comReviewed-by: Matthew Bobrowski <repnop@google.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/mark.c

@@ -493,8 +493,11 @@ static int fsnotify_attach_connector_to_object(fsnotify_connp_t *connp,
 		conn->fsid.val[0] = conn->fsid.val[1] = 0;
 		conn->flags = 0;
 	}
-	if (conn->type == FSNOTIFY_OBJ_TYPE_INODE)
-		inode = igrab(fsnotify_conn_inode(conn));
+	if (conn->type == FSNOTIFY_OBJ_TYPE_INODE) {
+		inode = fsnotify_conn_inode(conn);
+		ihold(inode);
+	}
+
 	/*
 	 * cmpxchg() provides the barrier so that readers of *connp can see
 	 * only initialized structure