configfs: don't bother with checks for mkdir/rmdir/unlink/symlink in root

just give root directory separate inode_operations without all those
methods...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/configfs/configfs_internal.h

@@ -89,6 +89,7 @@ extern const struct file_operations configfs_dir_operations;
 extern const struct file_operations configfs_file_operations;
 extern const struct file_operations bin_fops;
 extern const struct inode_operations configfs_dir_inode_operations;
+extern const struct inode_operations configfs_root_inode_operations;
 extern const struct inode_operations configfs_symlink_inode_operations;
 extern const struct dentry_operations configfs_dentry_ops;
 

fs/configfs/dir.c

@@ -1183,11 +1183,6 @@ static int configfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
 	struct module *subsys_owner = NULL, *new_item_owner = NULL;
 	char *name;
 
-	if (dentry->d_parent == configfs_sb->s_root) {
-		ret = -EPERM;
-		goto out;
-	}
-
 	sd = dentry->d_parent->d_fsdata;
 
 	/*
@@ -1359,9 +1354,6 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 	struct module *subsys_owner = NULL, *dead_item_owner = NULL;
 	int ret;
 
-	if (dentry->d_parent == configfs_sb->s_root)
-		return -EPERM;
-
 	sd = dentry->d_fsdata;
 	if (sd->s_type & CONFIGFS_USET_DEFAULT)
 		return -EPERM;
@@ -1459,6 +1451,11 @@ const struct inode_operations configfs_dir_inode_operations = {
 	.setattr	= configfs_setattr,
 };
 
+const struct inode_operations configfs_root_inode_operations = {
+	.lookup		= configfs_lookup,
+	.setattr	= configfs_setattr,
+};
+
 #if 0
 int configfs_rename_dir(struct config_item * item, const char *new_name)
 {

fs/configfs/mount.c

@@ -82,7 +82,7 @@ static int configfs_fill_super(struct super_block *sb, void *data, int silent)
 	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
 				   &configfs_root);
 	if (inode) {
-		inode->i_op = &configfs_dir_inode_operations;
+		inode->i_op = &configfs_root_inode_operations;
 		inode->i_fop = &configfs_dir_operations;
 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
 		inc_nlink(inode);

fs/configfs/symlink.c

@@ -141,10 +141,6 @@ int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symna
 	struct config_item *target_item = NULL;
 	struct config_item_type *type;
 
-	ret = -EPERM;  /* What lack-of-symlink returns */
-	if (dentry->d_parent == configfs_sb->s_root)
-		goto out;
-
 	sd = dentry->d_parent->d_fsdata;
 	/*
 	 * Fake invisibility if dir belongs to a group/default groups hierarchy
@@ -198,8 +194,6 @@ int configfs_unlink(struct inode *dir, struct dentry *dentry)
 	if (!(sd->s_type & CONFIGFS_ITEM_LINK))
 		goto out;
 
-	BUG_ON(dentry->d_parent == configfs_sb->s_root);
-
 	sl = sd->s_element;
 
 	parent_item = configfs_get_config_item(dentry->d_parent);