cifs: do not search for channel if server is terminating

[ Upstream commit 88675b22d34e6e815ad4bde09c590ccb2d50c59d ]

In order to scale down the channels, the following sequence
of operations happen:
1. server struct is marked for terminate
2. the channel is deallocated in the ses->chans array
3. at a later point the cifsd thread actually terminates the server

Between 2 and 3, there can be calls to find the channel for
a server struct. When that happens, there can be an ugly warning
that's logged. But this is expected.

So this change does two things:
1. in cifs_ses_get_chan_index, if server->terminate is set, return
2. always make sure server->terminate is set with chan_lock held

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/smb/client/sess.c b/fs/smb/client/sess.c
index a20a5d0836dc910312edba30759b66c099022b54..52f7a411e2bbfd49a837420d2cfc55b5b9d9c974 100644 (file)
--- a/fs/smb/client/sess.c
+++ b/fs/smb/client/sess.c
@@ -75,6 +75,10 @@ cifs_ses_get_chan_index(struct cifs_ses *ses,
 {
        unsigned int i;
 
+       /* if the channel is waiting for termination */
+       if (server->terminate)
+               return CIFS_INVAL_CHAN_INDEX;
+
        for (i = 0; i < ses->chan_count; i++) {
                if (ses->chans[i].server == server)
                        return i;

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index ce2d28537bc8af8c9b8c8dde434d1eb1b438d838..97fc2f85b429dfcf8d21f594005e7a9ca5115d14 100644 (file)
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -178,6 +178,7 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses,
                }
 
                ses->chans[chan_index].server = NULL;
+               server->terminate = true;
                spin_unlock(&ses->chan_lock);
 
                /*
@@ -188,7 +189,6 @@ cifs_chan_skip_or_disable(struct cifs_ses *ses,
                 */
                cifs_put_tcp_session(server, from_reconnect);
 
-               server->terminate = true;
                cifs_signal_cifsd_for_reconnect(server, false);
 
                /* mark primary server as needing reconnect */