From ee1d21794e55ab76505745d24101331552182002 Mon Sep 17 00:00:00 2001 From: Shyam Prasad N Date: Fri, 13 Oct 2023 11:40:09 +0000 Subject: cifs: handle when server stops supporting multichannel When a server stops supporting multichannel, we will keep attempting reconnects to the secondary channels today. Avoid this by freeing extra channels when negotiate returns no multichannel support. Signed-off-by: Shyam Prasad N Signed-off-by: Steve French --- fs/smb/client/smb2pdu.c | 76 ++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 75 insertions(+), 1 deletion(-) (limited to 'fs/smb/client/smb2pdu.c') diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c index 0d4351e43069..2eb29fa278c3 100644 --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -164,6 +164,8 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, struct nls_table *nls_codepage = NULL; struct cifs_ses *ses; int xid; + struct TCP_Server_Info *pserver; + unsigned int chan_index; /* * SMB2s NegProt, SessSetup, Logoff do not have tcon yet so @@ -224,6 +226,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon, return -EAGAIN; } } + + /* if server is marked for termination, cifsd will cleanup */ + if (server->terminate) { + spin_unlock(&server->srv_lock); + return -EHOSTDOWN; + } spin_unlock(&server->srv_lock); again: @@ -242,12 +250,24 @@ again: tcon->need_reconnect); mutex_lock(&ses->session_mutex); + /* + * if this is called by delayed work, and the channel has been disabled + * in parallel, the delayed work can continue to execute in parallel + * there's a chance that this channel may not exist anymore + */ + spin_lock(&server->srv_lock); + if (server->tcpStatus == CifsExiting) { + spin_unlock(&server->srv_lock); + mutex_unlock(&ses->session_mutex); + rc = -EHOSTDOWN; + goto out; + } + /* * Recheck after acquire mutex. If another thread is negotiating * and the server never sends an answer the socket will be closed * and tcpStatus set to reconnect. */ - spin_lock(&server->srv_lock); if (server->tcpStatus == CifsNeedReconnect) { spin_unlock(&server->srv_lock); mutex_unlock(&ses->session_mutex); @@ -284,6 +304,53 @@ again: rc = cifs_negotiate_protocol(0, ses, server); if (!rc) { + /* + * if server stopped supporting multichannel + * and the first channel reconnected, disable all the others. + */ + if (ses->chan_count > 1 && + !(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) { + if (SERVER_IS_CHAN(server)) { + cifs_dbg(VFS, "server %s does not support " \ + "multichannel anymore. skipping secondary channel\n", + ses->server->hostname); + + spin_lock(&ses->chan_lock); + chan_index = cifs_ses_get_chan_index(ses, server); + if (chan_index == CIFS_INVAL_CHAN_INDEX) { + spin_unlock(&ses->chan_lock); + goto skip_terminate; + } + + ses->chans[chan_index].server = NULL; + spin_unlock(&ses->chan_lock); + + /* + * the above reference of server by channel + * needs to be dropped without holding chan_lock + * as cifs_put_tcp_session takes a higher lock + * i.e. cifs_tcp_ses_lock + */ + cifs_put_tcp_session(server, 1); + + server->terminate = true; + cifs_signal_cifsd_for_reconnect(server, false); + + /* mark primary server as needing reconnect */ + pserver = server->primary_server; + cifs_signal_cifsd_for_reconnect(pserver, false); + +skip_terminate: + mutex_unlock(&ses->session_mutex); + rc = -EHOSTDOWN; + goto out; + } else { + cifs_server_dbg(VFS, "does not support " \ + "multichannel anymore. disabling all other channels\n"); + cifs_disable_secondary_channels(ses); + } + } + rc = cifs_setup_session(0, ses, server, nls_codepage); if ((rc == -EACCES) && !tcon->retry) { mutex_unlock(&ses->session_mutex); @@ -3836,6 +3903,13 @@ void smb2_reconnect_server(struct work_struct *work) /* Prevent simultaneous reconnects that can corrupt tcon->rlist list */ mutex_lock(&pserver->reconnect_mutex); + /* if the server is marked for termination, drop the ref count here */ + if (server->terminate) { + cifs_put_tcp_session(server, true); + mutex_unlock(&pserver->reconnect_mutex); + return; + } + INIT_LIST_HEAD(&tmp_list); INIT_LIST_HEAD(&tmp_ses_list); cifs_dbg(FYI, "Reconnecting tcons and channels\n"); -- cgit v1.2.3