linux-kernel - [PATCH 5.10 041/299] cifs: detect dead connections only when echoes are enabled.

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Date:   Mon, 10 May 2021 12:17:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Shyam Prasad N <sprasad@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>
Subject: [PATCH 5.10 041/299] cifs: detect dead connections only when echoes are enabled.

From: Shyam Prasad N <sprasad@...rosoft.com>

commit f4916649f98e2c7bdba38c6597a98c456c17317d 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: Shyam Prasad N <sprasad@...rosoft.com>
CC: <stable@...r.kernel.org> # v5.8+
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/cifs/connect.c |    1 +
 1 file changed, 1 insertion(+)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -663,6 +663,7 @@ server_unresponsive(struct TCP_Server_In
 	 */
 	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);