smb: client: fix hang in wait_for_response() for negproto

[ Upstream commit 7ccc1465465d78e6411b7bd730d06e7435802b5c ]

Call cifs_reconnect() to wake up processes waiting on negotiate
protocol to handle the case where server abruptly shut down and had no
chance to properly close the socket.

Simple reproducer:

  ssh 192.168.2.100 pkill -STOP smbd
  mount.cifs //192.168.2.100/test /mnt -o ... [never returns]

Cc: Rickard Andersson <rickaran@axis.com>
Signed-off-by: Paulo Alcantara (Red Hat) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index d2307162a2de15ec01462d49b8ce3191a0be9f66..e325e06357ffb709836bccdb03e856ae16019fae 100644 (file)
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -656,6 +656,19 @@ allocate_buffers(struct TCP_Server_Info *server)
 static bool
 server_unresponsive(struct TCP_Server_Info *server)
 {
+       /*
+        * If we're in the process of mounting a share or reconnecting a session
+        * and the server abruptly shut down (e.g. socket wasn't closed, packet
+        * had been ACK'ed but no SMB response), don't wait longer than 20s to
+        * negotiate protocol.
+        */
+       spin_lock(&server->srv_lock);
+       if (server->tcpStatus == CifsInNegotiate &&
+           time_after(jiffies, server->lstrp + 20 * HZ)) {
+               spin_unlock(&server->srv_lock);
+               cifs_reconnect(server, false);
+               return true;
+       }
        /*
         * We need to wait 3 echo intervals to make sure we handle such
         * situations right:
@@ -667,7 +680,6 @@ server_unresponsive(struct TCP_Server_Info *server)
         * 65s kernel_recvmsg times out, and we see that we haven't gotten
         *     a response in >60s.
         */
-       spin_lock(&server->srv_lock);
        if ((server->tcpStatus == CifsGood ||
            server->tcpStatus == CifsNeedNegotiate) &&
            (!server->ops->can_echo || server->ops->can_echo(server)) &&