cifs: fix leak of iface for primary channel

jira LE-4669
Rebuild_History Non-Buildable kernel-4.18.0-553.82.1.el8_10
commit-author Shyam Prasad N <sprasad@microsoft.com>
commit 29954d5

My last change in this area introduced a change which
accounted for primary channel in the interface ref count.
However, it did not reduce this ref count on deallocation
of the primary channel. i.e. during umount.

Fixing this leak here, by dropping this ref count for
primary channel while freeing up the session.

Fixes: fa1d050 ("cifs: account for primary channel in the interface list")
	Cc: stable@vger.kernel.org
	Reported-by: Paulo Alcantara <pc@manguebit.com>
	Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
	Signed-off-by: Steve French <stfrench@microsoft.com>
(cherry picked from commit 29954d5)
	Signed-off-by: Jonathan Maple <jmaple@ciq.com>

Author: PlaidCat

fs/cifs/connect.c

@@ -1851,6 +1851,12 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
 		}
 	}
 
+	/* we now account for primary channel in iface->refcount */
+	if (ses->chans[0].iface) {
+		kref_put(&ses->chans[0].iface->refcount, release_iface);
+		ses->chans[0].server = NULL;
+	}
+
 	sesInfoFree(ses);
 	cifs_put_tcp_session(server, 0);
 }