Merge tag '6.7-rc8-smb3-mchan-fixes' of git://git.samba.org/sfrench/cifs-2.6

Pull smb client fixes from Steve French:
 "Three important multichannel smb3 client fixes found in recent
  testing:

   - fix oops due to incorrect refcounting of interfaces after
     disabling multichannel

   - fix possible unrecoverable session state after disabling
     multichannel with active sessions

   - fix two places that were missing use of chan_lock"

* tag '6.7-rc8-smb3-mchan-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: do not depend on release_iface for maintaining iface_list
  cifs: cifs_chan_is_iface_active should be called with chan_lock held
  cifs: after disabling multichannel, mark tcon for reconnect

3 files changed, 40 insertions, 22 deletions

diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 55b3ce944022..5e32c79f03a7 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -994,7 +994,6 @@ release_iface(struct kref *ref)
 	struct cifs_server_iface *iface = container_of(ref,
 						       struct cifs_server_iface,
 						       refcount);
-	list_del_init(&iface->iface_head);
 	kfree(iface);
 }
 
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index dd2a1fb65e71..dc9b95ca71e6 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -216,22 +216,29 @@ cifs_mark_tcp_ses_conns_for_reconnect(struct TCP_Server_Info *server,
 	/* If server is a channel, select the primary channel */
 	pserver = SERVER_IS_CHAN(server) ? server->primary_server : server;
 
+	/*
+	 * if the server has been marked for termination, there is a
+	 * chance that the remaining channels all need reconnect. To be
+	 * on the safer side, mark the session and trees for reconnect
+	 * for this scenario. This might cause a few redundant session
+	 * setup and tree connect requests, but it is better than not doing
+	 * a tree connect when needed, and all following requests failing
+	 */
+	if (server->terminate) {
+		mark_smb_session = true;
+		server = pserver;
+	}
 
 	spin_lock(&cifs_tcp_ses_lock);
 	list_for_each_entry_safe(ses, nses, &pserver->smb_ses_list, smb_ses_list) {
-		/*
-		 * if channel has been marked for termination, nothing to do
-		 * for the channel. in fact, we cannot find the channel for the
-		 * server. So safe to exit here
-		 */
-		if (server->terminate)
-			break;
-
 		/* check if iface is still active */
-		if (!cifs_chan_is_iface_active(ses, server))
+		spin_lock(&ses->chan_lock);
+		if (!cifs_chan_is_iface_active(ses, server)) {
+			spin_unlock(&ses->chan_lock);
 			cifs_chan_update_iface(ses, server);
+			spin_lock(&ses->chan_lock);
+		}
 
-		spin_lock(&ses->chan_lock);
 		if (!mark_smb_session && cifs_chan_needs_reconnect(ses, server)) {
 			spin_unlock(&ses->chan_lock);
 			continue;
diff --git a/fs/smb/client/smb2ops.c b/fs/smb/client/smb2ops.c
index 66b310208545..14bc745de199 100644
--- a/fs/smb/client/smb2ops.c
+++ b/fs/smb/client/smb2ops.c
@@ -595,16 +595,12 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 	}
 
 	/*
-	 * Go through iface_list and do kref_put to remove
-	 * any unused ifaces. ifaces in use will be removed
-	 * when the last user calls a kref_put on it
+	 * Go through iface_list and mark them as inactive
 	 */
 	list_for_each_entry_safe(iface, niface, &ses->iface_list,
-				 iface_head) {
+				 iface_head)
 		iface->is_active = 0;
-		kref_put(&iface->refcount, release_iface);
-		ses->iface_count--;
-	}
+
 	spin_unlock(&ses->iface_lock);
 
 	/*
@@ -678,10 +674,7 @@ parse_server_interfaces(struct network_interface_info_ioctl_rsp *buf,
 					 iface_head) {
 			ret = iface_cmp(iface, &tmp_iface);
 			if (!ret) {
-				/* just get a ref so that it doesn't get picked/freed */
 				iface->is_active = 1;
-				kref_get(&iface->refcount);
-				ses->iface_count++;
 				spin_unlock(&ses->iface_lock);
 				goto next_iface;
 			} else if (ret < 0) {
@@ -748,6 +741,20 @@ next_iface:
 	}
 
 out:
+	/*
+	 * Go through the list again and put the inactive entries
+	 */
+	spin_lock(&ses->iface_lock);
+	list_for_each_entry_safe(iface, niface, &ses->iface_list,
+				 iface_head) {
+		if (!iface->is_active) {
+			list_del(&iface->iface_head);
+			kref_put(&iface->refcount, release_iface);
+			ses->iface_count--;
+		}
+	}
+	spin_unlock(&ses->iface_lock);
+
 	return rc;
 }
 
@@ -784,9 +791,14 @@ SMB3_request_interfaces(const unsigned int xid, struct cifs_tcon *tcon, bool in_
 		goto out;
 
 	/* check if iface is still active */
+	spin_lock(&ses->chan_lock);
 	pserver = ses->chans[0].server;
-	if (pserver && !cifs_chan_is_iface_active(ses, pserver))
+	if (pserver && !cifs_chan_is_iface_active(ses, pserver)) {
+		spin_unlock(&ses->chan_lock);
 		cifs_chan_update_iface(ses, pserver);
+		spin_lock(&ses->chan_lock);
+	}
+	spin_unlock(&ses->chan_lock);
 
 out:
 	kfree(out_buf);