dir.c

linux 内核源代码

	struct configfs_dirent *sd;

	/*
	 * Since we can trust everything is pinned, we just need i_mutex
	 * on the item.
	 */
	mutex_lock(&target->ci_dentry->d_inode->i_mutex);

	sd = target->ci_dentry->d_fsdata;
	BUG_ON(sd->s_dependent_count < 1);

	sd->s_dependent_count -= 1;

	/*
	 * After this unlock, we cannot trust the item to stay alive!
	 * DO NOT REFERENCE item after this unlock.
	 */
	mutex_unlock(&target->ci_dentry->d_inode->i_mutex);
}
EXPORT_SYMBOL(configfs_undepend_item);

static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int ret, module_got = 0;
	struct config_group *group;
	struct config_item *item;
	struct config_item *parent_item;
	struct configfs_subsystem *subsys;
	struct configfs_dirent *sd;
	struct config_item_type *type;
	struct module *owner = NULL;
	char *name;

	if (dentry->d_parent == configfs_sb->s_root) {
		ret = -EPERM;
		goto out;
	}

	sd = dentry->d_parent->d_fsdata;
	if (!(sd->s_type & CONFIGFS_USET_DIR)) {
		ret = -EPERM;
		goto out;
	}

	/* Get a working ref for the duration of this function */
	parent_item = configfs_get_config_item(dentry->d_parent);
	type = parent_item->ci_type;
	subsys = to_config_group(parent_item)->cg_subsys;
	BUG_ON(!subsys);

	if (!type || !type->ct_group_ops ||
	    (!type->ct_group_ops->make_group &&
	     !type->ct_group_ops->make_item)) {
		ret = -EPERM;  /* Lack-of-mkdir returns -EPERM */
		goto out_put;
	}

	name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
	if (!name) {
		ret = -ENOMEM;
		goto out_put;
	}

	snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);

	mutex_lock(&subsys->su_mutex);
	group = NULL;
	item = NULL;
	if (type->ct_group_ops->make_group) {
		group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
		if (group) {
			link_group(to_config_group(parent_item), group);
			item = &group->cg_item;
		}
	} else {
		item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
		if (item)
			link_obj(parent_item, item);
	}
	mutex_unlock(&subsys->su_mutex);

	kfree(name);
	if (!item) {
		/*
		 * If item == NULL, then link_obj() was never called.
		 * There are no extra references to clean up.
		 */
		ret = -ENOMEM;
		goto out_put;
	}

	/*
	 * link_obj() has been called (via link_group() for groups).
	 * From here on out, errors must clean that up.
	 */

	type = item->ci_type;
	if (!type) {
		ret = -EINVAL;
		goto out_unlink;
	}

	owner = type->ct_owner;
	if (!try_module_get(owner)) {
		ret = -EINVAL;
		goto out_unlink;
	}

	/*
	 * I hate doing it this way, but if there is
	 * an error,  module_put() probably should
	 * happen after any cleanup.
	 */
	module_got = 1;

	if (group)
		ret = configfs_attach_group(parent_item, item, dentry);
	else
		ret = configfs_attach_item(parent_item, item, dentry);

out_unlink:
	if (ret) {
		/* Tear down everything we built up */
		mutex_lock(&subsys->su_mutex);

		client_disconnect_notify(parent_item, item);
		if (group)
			unlink_group(group);
		else
			unlink_obj(item);
		client_drop_item(parent_item, item);

		mutex_unlock(&subsys->su_mutex);

		if (module_got)
			module_put(owner);
	}

out_put:
	/*
	 * link_obj()/link_group() took a reference from child->parent,
	 * so the parent is safely pinned.  We can drop our working
	 * reference.
	 */
	config_item_put(parent_item);

out:
	return ret;
}

static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
{
	struct config_item *parent_item;
	struct config_item *item;
	struct configfs_subsystem *subsys;
	struct configfs_dirent *sd;
	struct module *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;

	/*
	 * Here's where we check for dependents.  We're protected by
	 * i_mutex.
	 */
	if (sd->s_dependent_count)
		return -EBUSY;

	/* Get a working ref until we have the child */
	parent_item = configfs_get_config_item(dentry->d_parent);
	subsys = to_config_group(parent_item)->cg_subsys;
	BUG_ON(!subsys);

	if (!parent_item->ci_type) {
		config_item_put(parent_item);
		return -EINVAL;
	}

	ret = configfs_detach_prep(dentry);
	if (ret) {
		configfs_detach_rollback(dentry);
		config_item_put(parent_item);
		return ret;
	}

	/* Get a working ref for the duration of this function */
	item = configfs_get_config_item(dentry);

	/* Drop reference from above, item already holds one. */
	config_item_put(parent_item);

	if (item->ci_type)
		owner = item->ci_type->ct_owner;

	if (sd->s_type & CONFIGFS_USET_DIR) {
		configfs_detach_group(item);

		mutex_lock(&subsys->su_mutex);
		client_disconnect_notify(parent_item, item);
		unlink_group(to_config_group(item));
	} else {
		configfs_detach_item(item);

		mutex_lock(&subsys->su_mutex);
		client_disconnect_notify(parent_item, item);
		unlink_obj(item);
	}

	client_drop_item(parent_item, item);
	mutex_unlock(&subsys->su_mutex);

	/* Drop our reference from above */
	config_item_put(item);

	module_put(owner);

	return 0;
}

const struct inode_operations configfs_dir_inode_operations = {
	.mkdir		= configfs_mkdir,
	.rmdir		= configfs_rmdir,
	.symlink	= configfs_symlink,
	.unlink		= configfs_unlink,
	.lookup		= configfs_lookup,
	.setattr	= configfs_setattr,
};

#if 0
int configfs_rename_dir(struct config_item * item, const char *new_name)
{
	int error = 0;
	struct dentry * new_dentry, * parent;

	if (!strcmp(config_item_name(item), new_name))
		return -EINVAL;

	if (!item->parent)
		return -EINVAL;

	down_write(&configfs_rename_sem);
	parent = item->parent->dentry;

	mutex_lock(&parent->d_inode->i_mutex);

	new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
	if (!IS_ERR(new_dentry)) {
		if (!new_dentry->d_inode) {
			error = config_item_set_name(item, "%s", new_name);
			if (!error) {
				d_add(new_dentry, NULL);
				d_move(item->dentry, new_dentry);
			}
			else
				d_delete(new_dentry);
		} else
			error = -EEXIST;
		dput(new_dentry);
	}
	mutex_unlock(&parent->d_inode->i_mutex);
	up_write(&configfs_rename_sem);

	return error;
}
#endif

static int configfs_dir_open(struct inode *inode, struct file *file)
{
	struct dentry * dentry = file->f_path.dentry;
	struct configfs_dirent * parent_sd = dentry->d_fsdata;

	mutex_lock(&dentry->d_inode->i_mutex);
	file->private_data = configfs_new_dirent(parent_sd, NULL);
	mutex_unlock(&dentry->d_inode->i_mutex);

	return file->private_data ? 0 : -ENOMEM;

}

static int configfs_dir_close(struct inode *inode, struct file *file)
{
	struct dentry * dentry = file->f_path.dentry;
	struct configfs_dirent * cursor = file->private_data;

	mutex_lock(&dentry->d_inode->i_mutex);
	list_del_init(&cursor->s_sibling);
	mutex_unlock(&dentry->d_inode->i_mutex);

	release_configfs_dirent(cursor);

	return 0;
}

/* Relationship between s_mode and the DT_xxx types */
static inline unsigned char dt_type(struct configfs_dirent *sd)
{
	return (sd->s_mode >> 12) & 15;
}

static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
	struct dentry *dentry = filp->f_path.dentry;
	struct configfs_dirent * parent_sd = dentry->d_fsdata;
	struct configfs_dirent *cursor = filp->private_data;
	struct list_head *p, *q = &cursor->s_sibling;
	ino_t ino;
	int i = filp->f_pos;

	switch (i) {
		case 0:
			ino = dentry->d_inode->i_ino;
			if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		case 1:
			ino = parent_ino(dentry);
			if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
				break;
			filp->f_pos++;
			i++;
			/* fallthrough */
		default:
			if (filp->f_pos == 2) {
				list_move(q, &parent_sd->s_children);
			}
			for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
				struct configfs_dirent *next;
				const char * name;
				int len;

				next = list_entry(p, struct configfs_dirent,
						   s_sibling);
				if (!next->s_element)
					continue;

				name = configfs_get_name(next);
				len = strlen(name);
				if (next->s_dentry)
					ino = next->s_dentry->d_inode->i_ino;
				else
					ino = iunique(configfs_sb, 2);

				if (filldir(dirent, name, len, filp->f_pos, ino,
						 dt_type(next)) < 0)
					return 0;

				list_move(q, p);
				p = q;
				filp->f_pos++;
			}
	}
	return 0;
}

static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
{
	struct dentry * dentry = file->f_path.dentry;

	mutex_lock(&dentry->d_inode->i_mutex);
	switch (origin) {
		case 1:
			offset += file->f_pos;
		case 0:
			if (offset >= 0)
				break;
		default:
			mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
			return -EINVAL;
	}
	if (offset != file->f_pos) {
		file->f_pos = offset;
		if (file->f_pos >= 2) {
			struct configfs_dirent *sd = dentry->d_fsdata;
			struct configfs_dirent *cursor = file->private_data;
			struct list_head *p;
			loff_t n = file->f_pos - 2;

			list_del(&cursor->s_sibling);
			p = sd->s_children.next;
			while (n && p != &sd->s_children) {
				struct configfs_dirent *next;
				next = list_entry(p, struct configfs_dirent,
						   s_sibling);
				if (next->s_element)
					n--;
				p = p->next;
			}
			list_add_tail(&cursor->s_sibling, p);
		}
	}
	mutex_unlock(&dentry->d_inode->i_mutex);
	return offset;
}

const struct file_operations configfs_dir_operations = {
	.open		= configfs_dir_open,
	.release	= configfs_dir_close,
	.llseek		= configfs_dir_lseek,
	.read		= generic_read_dir,
	.readdir	= configfs_readdir,
};

int configfs_register_subsystem(struct configfs_subsystem *subsys)
{
	int err;
	struct config_group *group = &subsys->su_group;
	struct qstr name;
	struct dentry *dentry;
	struct configfs_dirent *sd;

	err = configfs_pin_fs();
	if (err)
		return err;

	if (!group->cg_item.ci_name)
		group->cg_item.ci_name = group->cg_item.ci_namebuf;

	sd = configfs_sb->s_root->d_fsdata;
	link_group(to_config_group(sd->s_element), group);

	mutex_lock(&configfs_sb->s_root->d_inode->i_mutex);

	name.name = group->cg_item.ci_name;
	name.len = strlen(name.name);
	name.hash = full_name_hash(name.name, name.len);

	err = -ENOMEM;
	dentry = d_alloc(configfs_sb->s_root, &name);
	if (dentry) {
		d_add(dentry, NULL);

		err = configfs_attach_group(sd->s_element, &group->cg_item,
					    dentry);
		if (err) {
			d_delete(dentry);
			dput(dentry);
		}
	}

	mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);

	if (err) {
		unlink_group(group);
		configfs_release_fs();
	}

	return err;
}

void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
{
	struct config_group *group = &subsys->su_group;
	struct dentry *dentry = group->cg_item.ci_dentry;

	if (dentry->d_parent != configfs_sb->s_root) {
		printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
		return;
	}

	mutex_lock_nested(&configfs_sb->s_root->d_inode->i_mutex,
			  I_MUTEX_PARENT);
	mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
	if (configfs_detach_prep(dentry)) {
		printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
	}
	configfs_detach_group(&group->cg_item);
	dentry->d_inode->i_flags |= S_DEAD;
	mutex_unlock(&dentry->d_inode->i_mutex);

	d_delete(dentry);

	mutex_unlock(&configfs_sb->s_root->d_inode->i_mutex);

	dput(dentry);

	unlink_group(group);
	configfs_release_fs();
}

EXPORT_SYMBOL(configfs_register_subsystem);
EXPORT_SYMBOL(configfs_unregister_subsystem);