fuse: readdirplus: fix instantiate

Fuse does instantiation slightly differently from NFS/CIFS which use
d_materialise_unique().

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org

fs/fuse/dir.c

@@ -1272,10 +1272,19 @@ static int fuse_direntplus_link(struct file *file,
 	if (!inode)
 		goto out;
 
-	alias = d_materialise_unique(dentry, inode);
-	err = PTR_ERR(alias);
-	if (IS_ERR(alias))
-		goto out;
+	if (S_ISDIR(inode->i_mode)) {
+		mutex_lock(&fc->inst_mutex);
+		alias = fuse_d_add_directory(dentry, inode);
+		mutex_unlock(&fc->inst_mutex);
+		err = PTR_ERR(alias);
+		if (IS_ERR(alias)) {
+			iput(inode);
+			goto out;
+		}
+	} else {
+		alias = d_splice_alias(inode, dentry);
+	}
+
 	if (alias) {
 		dput(dentry);
 		dentry = alias;