cifs: detect dead connections only when echoes are enabled.

stable inclusion
from stable-5.10.36
commit 8a90058752e0b04b3159fa889a7f611b550bf816
bugzilla: 51867
CVE: NA

--------------------------------

commit f4916649 upstream.

We can detect server unresponsiveness only if echoes are enabled.
Echoes can be disabled under two scenarios:
1. The connection is low on credits, so we've disabled echoes/oplocks.
2. The connection has not seen any request till now (other than
negotiate/sess-setup), which is when we enable these two, based on
the credits available.

So this fix will check for dead connection, only when echo is enabled.
Signed-off-by: NShyam Prasad N <sprasad@microsoft.com>
CC: <stable@vger.kernel.org> # v5.8+
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

fs/cifs/connect.c

@@ -663,6 +663,7 @@ server_unresponsive(struct TCP_Server_Info *server)
 	 */
 	if ((server->tcpStatus == CifsGood ||
 	    server->tcpStatus == CifsNeedNegotiate) &&
+	    (!server->ops->can_echo || server->ops->can_echo(server)) &&
 	    time_after(jiffies, server->lstrp + 3 * server->echo_interval)) {
 		cifs_server_dbg(VFS, "has not responded in %lu seconds. Reconnecting...\n",
 			 (3 * server->echo_interval) / HZ);