fs: encode_fh: return FILEID_INVALID if invalid fid_type

This patch is a follow up on below patch:

[PATCH] exportfs: add FILEID_INVALID to indicate invalid fid_type
commit: 216b6cbdcbd86b1db0754d58886b466ae31f5a63

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Sage Weil <sage@inktank.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/mm/cleancache.c b/mm/cleancache.c
index 32e6f41..d76ba74 100644
--- a/mm/cleancache.c
+++ b/mm/cleancache.c
@@ -89,7 +89,7 @@
 		fhfn = sb->s_export_op->encode_fh;
 		if  (fhfn) {
 			len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL);
-			if (len <= 0 || len == 255)
+			if (len <= FILEID_ROOT || len == FILEID_INVALID)
 				return -1;
 			if (maxlen > CLEANCACHE_KEY_MAX)
 				return -1;