block/rnbd-srv: Protect dev session sysfs removal

Since the removal of the session sysfs can also be called from the
function destroy_sess, there is a need to protect the call from the
function rnbd_srv_sess_dev_force_close

Fixes: 78699805 ("block/rnbd-srv: close a mapped device from server side.")
Signed-off-by: NMd Haris Iqbal <haris.iqbal@cloud.ionos.com>
Reviewed-by: NGuoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: NJack Wang <jinpu.wang@cloud.ionos.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-srv.c

@@ -338,9 +338,10 @@ static int rnbd_srv_link_ev(struct rtrs_srv *rtrs,
 
 void rnbd_srv_sess_dev_force_close(struct rnbd_srv_sess_dev *sess_dev)
 {
+	mutex_lock(&sess_dev->sess->lock);
 	rnbd_srv_destroy_dev_session_sysfs(sess_dev);
+	mutex_unlock(&sess_dev->sess->lock);
 	sess_dev->keep_id = true;
-
 }
 
 static int process_msg_close(struct rtrs_srv *rtrs,