Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fbc8d4c0 authored by Nick Piggin's avatar Nick Piggin
Browse files

config fs: avoid switching ->d_op on live dentry 



Switching d_op on a live dentry is racy in general, so avoid it. In this case
it is a negative dentry, which is safer, but there are still concurrent ops
which may be called on d_op in that case (eg. d_revalidate). So in general
a filesystem may not do this. Fix configfs so as not to do this.

Signed-off-by: default avatarNick Piggin <npiggin@kernel.dk>
parent 5adcee1d

fs/configfs/dir.c

+9 −8
Original line number Diff line number Diff line
@@ -232,10 +232,8 @@ int configfs_make_dirent(struct configfs_dirent * parent_sd, 


	sd->s_mode = mode;

	sd->s_dentry = dentry;

	if (dentry) {

	if (dentry)

		dentry->d_fsdata = configfs_get(sd);

		dentry->d_op = &configfs_dentry_ops;

	}



	return 0;

}
@@ -278,7 +276,6 @@ static int create_dir(struct config_item * k, struct dentry * p, 
		error = configfs_create(d, mode, init_dir);

		if (!error) {

			inc_nlink(p->d_inode);

			(d)->d_op = &configfs_dentry_ops;

		} else {

			struct configfs_dirent *sd = d->d_fsdata;

			if (sd) {
@@ -371,9 +368,7 @@ int configfs_create_link(struct configfs_symlink *sl, 
				   CONFIGFS_ITEM_LINK);

	if (!err) {

		err = configfs_create(dentry, mode, init_symlink);

		if (!err)

			dentry->d_op = &configfs_dentry_ops;

		else {

		if (err) {

			struct configfs_dirent *sd = dentry->d_fsdata;

			if (sd) {

				spin_lock(&configfs_dirent_lock);
@@ -493,7 +488,11 @@ static struct dentry * configfs_lookup(struct inode *dir, 
		 * If it doesn't exist and it isn't a NOT_PINNED item,

		 * it must be negative.

		 */

		return simple_lookup(dir, dentry, nd);

		if (dentry->d_name.len > NAME_MAX)

			return ERR_PTR(-ENAMETOOLONG);

		dentry->d_op = &configfs_dentry_ops;

		d_add(dentry, NULL);

		return NULL;

	}



out:
@@ -685,6 +684,7 @@ static int create_default_group(struct config_group *parent_group, 
	ret = -ENOMEM;

	child = d_alloc(parent, &name);

	if (child) {

		child->d_op = &configfs_dentry_ops;

		d_add(child, NULL);



		ret = configfs_attach_group(&parent_group->cg_item,
@@ -1682,6 +1682,7 @@ int configfs_register_subsystem(struct configfs_subsystem *subsys) 
	err = -ENOMEM;

	dentry = d_alloc(configfs_sb->s_root, &name);

	if (dentry) {

		dentry->d_op = &configfs_dentry_ops;

		d_add(dentry, NULL);



		err = configfs_attach_group(sd->s_element, &group->cg_item,