fat: make sure to set d_ops in fat_get_parent

fat_get_parent needs to setup the dentry operations, otherwise we might
lose them when the NFS server needs to reconnect out of cache inodes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

fs/fat/inode.c

@@ -749,6 +749,8 @@ static struct dentry *fat_get_parent(struct dentry *child)
 	brelse(bh);
 
 	parent = d_obtain_alias(inode);
+	if (!IS_ERR(parent))
+		parent->d_op = sb->s_root->d_op;
 out:
 	unlock_super(sb);