fuse: fix root dentry initialization

Add missing dentry initialization to root dentry.

Fixes: f75fdf22b0a8 ("fuse: don't use ->d_time")
Reported-by: Andreas Reis <andreas.reis@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/fuse/dir.c

@@ -286,6 +286,11 @@ const struct dentry_operations fuse_dentry_operations = {
 	.d_release	= fuse_dentry_release,
 };
 
+const struct dentry_operations fuse_root_dentry_operations = {
+	.d_init		= fuse_dentry_init,
+	.d_release	= fuse_dentry_release,
+};
+
 int fuse_valid_type(int m)
 {
 	return S_ISREG(m) || S_ISDIR(m) || S_ISLNK(m) || S_ISCHR(m) ||

fs/fuse/fuse_i.h

@@ -692,6 +692,7 @@ static inline u64 get_node_id(struct inode *inode)
 extern const struct file_operations fuse_dev_operations;
 
 extern const struct dentry_operations fuse_dentry_operations;
+extern const struct dentry_operations fuse_root_dentry_operations;
 
 /**
  * Inode to nodeid comparison.

fs/fuse/inode.c

@@ -1131,10 +1131,11 @@ static int fuse_fill_super(struct super_block *sb, void *data, int silent)
 
 	err = -ENOMEM;
 	root = fuse_get_root_inode(sb, d.rootmode);
+	sb->s_d_op = &fuse_root_dentry_operations;
 	root_dentry = d_make_root(root);
 	if (!root_dentry)
 		goto err_dev_free;
-	/* only now - we want root dentry with NULL ->d_op */
+	/* Root dentry doesn't have .d_revalidate */
 	sb->s_d_op = &fuse_dentry_operations;
 
 	init_req = fuse_request_alloc(0);