smb3: extend fscache mount volume coherency check

It is better to check volume id and creation time, not just
the root inode number to verify if the volume has changed
when remounting.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cache.c

@@ -53,13 +53,6 @@ const struct fscache_cookie_def cifs_fscache_server_index_def = {
 	.type = FSCACHE_COOKIE_TYPE_INDEX,
 };
 
-/*
- * Auxiliary data attached to CIFS superblock within the cache
- */
-struct cifs_fscache_super_auxdata {
-	u64	resource_id;		/* unique server resource id */
-};
-
 char *extract_sharename(const char *treename)
 {
 	const char *src;
@@ -98,6 +91,8 @@ fscache_checkaux cifs_fscache_super_check_aux(void *cookie_netfs_data,
 
 	memset(&auxdata, 0, sizeof(auxdata));
 	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
 
 	if (memcmp(data, &auxdata, datalen) != 0)
 		return FSCACHE_CHECKAUX_OBSOLETE;