linux-kernel - [PATCH] smb: client: fix first command failure during re-negotiation

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Message-ID: <20250619011829.561614-1-zhangjian496@huawei.com>
Date: Thu, 19 Jun 2025 09:18:29 +0800
From: zhangjian <zhangjian496@...wei.com>
To: <stfrench@...rosoft.com>, <longli@...rosoft.com>,
	<wangzhaolong1@...wei.com>, <metze@...ba.org>, <dhowells@...hat.com>,
	<pc@...guebit.org>
CC: <linux-kernel@...r.kernel.org>, <linux-cifs@...r.kernel.org>
Subject: [PATCH] smb: client: fix first command failure during re-negotiation

after fabc4ed200f9, server_unresponsive add a condition to check whether client
need to reconnect depending on server->lstrp. When client failed to reconnect
for some time and abort connection, server->lstrp is updated for the last time.
In the following scene, server->lstrp is too old. This cause next command
failure in re-negotiation rather than waiting for re-negotiation done.

1. mount -t cifs -o username=Everyone,echo_internal=10 //$server_ip/export /mnt
2. ssh $server_ip "echo b > /proc/sysrq-trigger &"
3. ls /mnt
4. sleep 21s
5. ssh $server_ip "service firewalld stop"
6. ls # return EHOSTDOWN

If the interval between 5 and 6 is too small, 6 may trigger sending negotiation
request. Before backgrounding cifsd thread try to receive negotiation response
from server in cifs_readv_from_socket, server_unresponsive may trigger
cifs_reconnect which cause 6 to be failed:

ls thread
----------------
  smb2_negotiate
    server->tcpStatus = CifsInNegotiate
    compound_send_recv
      wait_for_compound_request

cifsd thread
----------------
  cifs_readv_from_socket
    server_unresponsive
      server->tcpStatus == CifsInNegotiate && jiffies > server->lstrp + 20s
        cifs_reconnect
          cifs_abort_connection: mid_state = MID_RETRY_NEEDED

ls thread
----------------
      cifs_sync_mid_result return EAGAIN
  smb2_negotiate return EHOSTDOWN

Though server->lstrp means last server response time, it is updated in
cifs_abort_connection and cifs_get_tcp_session. We can also update server->lstrp
before switching into CifsInNegotiate state to avoid failure in 6.

Fixes: fabc4ed200f9 ("smb: client: fix hang in wait_for_response() for negproto")
Signed-off-by: zhangjian <zhangjian496@...wei.com>
---
 fs/smb/client/connect.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index 28bc33496..f9aef60f1 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -4193,6 +4193,7 @@ cifs_negotiate_protocol(const unsigned int xid, struct cifs_ses *ses,
 		return 0;
 	}

+	server->lstrp = jiffies;
 	server->tcpStatus = CifsInNegotiate;
 	spin_unlock(&server->srv_lock);

-- 
2.33.0