cifs: connect individual channel servers to primary channel server

Today, we don't have any way to get the smb session for any
of the secondary channels. Introducing a pointer to the primary
server from server struct of any secondary channel. The value will
be NULL for the server of the primary channel. This will enable us
to get the smb session for any channel.

This will be needed for some of the changes that I'm planning
to make soon.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

1 files changed, 20 insertions, 4 deletions

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 09a532ed8fe4..f80b73f2d0a0 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -173,6 +173,7 @@ static void cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server
 	struct cifs_tcon *tcon;
 	struct mid_q_entry *mid, *nmid;
 	struct list_head retry_list;
+	struct TCP_Server_Info *pserver;
 
 	server->maxBuf = 0;
 	server->max_read = 0;
@@ -184,8 +185,12 @@ static void cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server
 	 * are not used until reconnected.
 	 */
 	cifs_dbg(FYI, "%s: marking sessions and tcons for reconnect\n", __func__);
+
+	/* If server is a channel, select the primary channel */
+	pserver = CIFS_SERVER_IS_CHAN(server) ? server->primary_server : server;
+
 	spin_lock(&cifs_tcp_ses_lock);
-	list_for_each_entry(ses, &server->smb_ses_list, smb_ses_list) {
+	list_for_each_entry(ses, &pserver->smb_ses_list, smb_ses_list) {
 		ses->need_reconnect = true;
 		list_for_each_entry(tcon, &ses->tcon_list, tcon_list)
 			tcon->need_reconnect = true;
@@ -1338,7 +1343,7 @@ cifs_find_tcp_session(struct smb3_fs_context *ctx)
 		 * Skip ses channels since they're only handled in lower layers
 		 * (e.g. cifs_send_recv).
 		 */
-		if (server->is_channel || !match_server(server, ctx))
+		if (CIFS_SERVER_IS_CHAN(server) || !match_server(server, ctx))
 			continue;
 
 		++server->srv_count;
@@ -1369,6 +1374,10 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 	list_del_init(&server->tcp_ses_list);
 	spin_unlock(&cifs_tcp_ses_lock);
 
+	/* For secondary channels, we pick up ref-count on the primary server */
+	if (CIFS_SERVER_IS_CHAN(server))
+		cifs_put_tcp_session(server->primary_server, from_reconnect);
+
 	cancel_delayed_work_sync(&server->echo);
 	cancel_delayed_work_sync(&server->resolve);
 
@@ -1401,7 +1410,8 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
 }
 
 struct TCP_Server_Info *
-cifs_get_tcp_session(struct smb3_fs_context *ctx)
+cifs_get_tcp_session(struct smb3_fs_context *ctx,
+		     struct TCP_Server_Info *primary_server)
 {
 	struct TCP_Server_Info *tcp_ses = NULL;
 	int rc;
@@ -1438,6 +1448,10 @@ cifs_get_tcp_session(struct smb3_fs_context *ctx)
 	tcp_ses->in_flight = 0;
 	tcp_ses->max_in_flight = 0;
 	tcp_ses->credits = 1;
+	if (primary_server) {
+		++primary_server->srv_count;
+		tcp_ses->primary_server = primary_server;
+	}
 	init_waitqueue_head(&tcp_ses->response_q);
 	init_waitqueue_head(&tcp_ses->request_q);
 	INIT_LIST_HEAD(&tcp_ses->pending_mid_q);
@@ -1559,6 +1573,8 @@ out_err_crypto_release:
 
 out_err:
 	if (tcp_ses) {
+		if (CIFS_SERVER_IS_CHAN(tcp_ses))
+			cifs_put_tcp_session(tcp_ses->primary_server, false);
 		kfree(tcp_ses->hostname);
 		if (tcp_ses->ssocket)
 			sock_release(tcp_ses->ssocket);
@@ -2960,7 +2976,7 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 	xid = get_xid();
 
 	/* get a reference to a tcp session */
-	server = cifs_get_tcp_session(ctx);
+	server = cifs_get_tcp_session(ctx, NULL);
 	if (IS_ERR(server)) {
 		rc = PTR_ERR(server);
 		server = NULL;