CIFS: fix automount for DFS shares

Automounting directories are now invalidated by .d_revalidate()
so to be d_instantiate()d again with the right DCACHE_NEED_AUTOMOUNT
flag

Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: Steve French <smfrench@gmail.com>

fs/cifs/dir.c

@@ -648,8 +648,16 @@ cifs_d_revalidate(struct dentry *direntry, struct nameidata *nd)
 	if (direntry->d_inode) {
 		if (cifs_revalidate_dentry(direntry))
 			return 0;
-		else
+		else {
+			/*
+			 * Forcibly invalidate automounting directory inodes
+			 * (remote DFS directories) so to have them
+			 * instantiated again for automount
+			 */
+			if (IS_AUTOMOUNT(direntry->d_inode))
+				return 0;
 			return 1;
+		}
 	}
 
 	/*