Commit 49c21e1c authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: check whiteout while reading directory 



Don't make a separate pass for checking whiteouts, since we can do it while
reading the upper directory.

This will make it easier to handle multiple layers.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent b2776bf7

fs/overlayfs/readdir.c

+28 −49
Original line number Diff line number Diff line
@@ -40,6 +40,7 @@ struct ovl_readdir_data { 
	struct rb_root root;

	struct list_head *list;

	struct list_head middle;

	struct dentry *dir;

	int count;

	int err;

};
@@ -126,6 +127,32 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, 
	if (p == NULL)

		return -ENOMEM;



	if (d_type == DT_CHR) {

		struct dentry *dentry;

		const struct cred *old_cred;

		struct cred *override_cred;



		override_cred = prepare_creds();

		if (!override_cred) {

			kfree(p);

			return -ENOMEM;

		}



		/*

		 * CAP_DAC_OVERRIDE for lookup

		 */

		cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);

		old_cred = override_creds(override_cred);



		dentry = lookup_one_len(name, rdd->dir, len);

		if (!IS_ERR(dentry)) {

			p->is_whiteout = ovl_is_whiteout(dentry);

			dput(dentry);

		}

		revert_creds(old_cred);

		put_cred(override_cred);

	}



	list_add_tail(&p->l_node, rdd->list);

	rb_link_node(&p->node, parent, newp);

	rb_insert_color(&p->node, &rdd->root);
@@ -231,49 +258,6 @@ static void ovl_dir_reset(struct file *file) 
		od->is_real = false;

}



static int ovl_dir_mark_whiteouts(struct dentry *dir,

				  struct ovl_readdir_data *rdd)

{

	struct ovl_cache_entry *p;

	struct dentry *dentry;

	const struct cred *old_cred;

	struct cred *override_cred;



	override_cred = prepare_creds();

	if (!override_cred) {

		ovl_cache_free(rdd->list);

		return -ENOMEM;

	}



	/*

	 * CAP_DAC_OVERRIDE for lookup

	 */

	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);

	old_cred = override_creds(override_cred);



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

	list_for_each_entry(p, rdd->list, l_node) {

		if (p->is_cursor)

			continue;



		if (p->type != DT_CHR)

			continue;



		dentry = lookup_one_len(p->name, dir, p->len);

		if (IS_ERR(dentry))

			continue;



		p->is_whiteout = ovl_is_whiteout(dentry);

		dput(dentry);

	}

	mutex_unlock(&dir->d_inode->i_mutex);



	revert_creds(old_cred);

	put_cred(override_cred);



	return 0;

}



static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list)

{

	int err;
@@ -290,15 +274,10 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) 
	ovl_path_upper(dentry, &upperpath);



	if (upperpath.dentry) {

		rdd.dir = upperpath.dentry;

		err = ovl_dir_read(&upperpath, &rdd);

		if (err)

			goto out;



		if (lowerpath.dentry) {

			err = ovl_dir_mark_whiteouts(upperpath.dentry, &rdd);

			if (err)

				goto out;

		}

	}

	if (lowerpath.dentry) {

		/*