smb3: do not setup the fscache_super_cookie until fsinfo initialized

We were calling cifs_fscache_get_super_cookie after tcon but before
we queried the info (QFS_Info) we need to initialize the cookie
properly.  Also includes an additional check suggested by Paulo
to make sure we don't initialize super cookie twice.
Suggested-by: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/connect.c

@@ -2350,8 +2350,6 @@ cifs_get_tcon(struct cifs_ses *ses, struct smb3_fs_context *ctx)
 	list_add(&tcon->tcon_list, &ses->tcon_list);
 	spin_unlock(&cifs_tcp_ses_lock);
 
-	cifs_fscache_get_super_cookie(tcon);
-
 	return tcon;
 
 out_fail:
@@ -3003,6 +3001,12 @@ static int mount_get_conns(struct mount_ctx *mnt_ctx)
 				cifs_dbg(VFS, "read only mount of RW share\n");
 			/* no need to log a RW mount of a typical RW share */
 		}
+		/*
+		 * The cookie is initialized from volume info returned above.
+		 * Inside cifs_fscache_get_super_cookie it checks
+		 * that we do not get super cookie twice.
+		 */
+		cifs_fscache_get_super_cookie(tcon);
 	}
 
 	/*

fs/cifs/fscache.c

@@ -87,6 +87,14 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 	char *sharename;
 	struct cifs_fscache_super_auxdata auxdata;
 
+	/*
+	 * Check if cookie was already initialized so don't reinitialize it.
+	 * In the future, as we integrate with newer fscache features,
+	 * we may want to instead add a check if cookie has changed
+	 */
+	if (tcon->fscache == NULL)
+		return;
+
 	sharename = extract_sharename(tcon->treeName);
 	if (IS_ERR(sharename)) {
 		cifs_dbg(FYI, "%s: couldn't extract sharename\n", __func__);