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Commit 3e01cee3 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: check whiteout on lowest layer as well 



Not checking whiteouts on lowest layer was an optimization (there's nothing
to white out there), but it could result in inconsitent behavior when a
layer previously used as upper/middle is later used as lowest. 

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
parent 3d3c6b89

fs/overlayfs/readdir.c

+40 −39
Original line number Original line Diff line number Diff line
@@ -80,14 +80,17 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, 
	return NULL;

	return NULL;

}

}





static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len,

static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,

						   const char *name, int len,

						   u64 ino, unsigned int d_type)

						   u64 ino, unsigned int d_type)

{

{

	struct ovl_cache_entry *p;

	struct ovl_cache_entry *p;

	size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);

	size_t size = offsetof(struct ovl_cache_entry, name[len + 1]);





	p = kmalloc(size, GFP_KERNEL);

	p = kmalloc(size, GFP_KERNEL);

	if (p) {

	if (!p)

		return NULL;



	memcpy(p->name, name, len);

	memcpy(p->name, name, len);

	p->name[len] = '\0';

	p->name[len] = '\0';

	p->len = len;

	p->len = len;
@@ -95,8 +98,32 @@ static struct ovl_cache_entry *ovl_cache_entry_new(const char *name, int len, 
	p->ino = ino;

	p->ino = ino;

	p->is_whiteout = false;

	p->is_whiteout = false;

	p->is_cursor = false;

	p->is_cursor = false;



	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 NULL;

		}

		}





		/*

		 * 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, dir, len);

		if (!IS_ERR(dentry)) {

			p->is_whiteout = ovl_is_whiteout(dentry);

			dput(dentry);

		}

		revert_creds(old_cred);

		put_cred(override_cred);

	}

	return p;

	return p;

}

}
@@ -123,36 +150,10 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, 
			return 0;

			return 0;

	}

	}





	p = ovl_cache_entry_new(name, len, ino, d_type);

	p = ovl_cache_entry_new(rdd->dir, name, len, ino, d_type);

	if (p == NULL)

	if (p == NULL)

		return -ENOMEM;

		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);

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

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

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

	rb_insert_color(&p->node, &rdd->root);

	rb_insert_color(&p->node, &rdd->root);
@@ -170,7 +171,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd, 
	if (p) {

	if (p) {

		list_move_tail(&p->l_node, &rdd->middle);

		list_move_tail(&p->l_node, &rdd->middle);

	} else {

	} else {

		p = ovl_cache_entry_new(name, namelen, ino, d_type);

		p = ovl_cache_entry_new(rdd->dir, name, namelen, ino, d_type);

		if (p == NULL)

		if (p == NULL)

			rdd->err = -ENOMEM;

			rdd->err = -ENOMEM;

		else

		else
@@ -229,6 +230,7 @@ static inline int ovl_dir_read(struct path *realpath, 
	if (IS_ERR(realfile))

	if (IS_ERR(realfile))

		return PTR_ERR(realfile);

		return PTR_ERR(realfile);





	rdd->dir = realpath->dentry;

	rdd->ctx.pos = 0;

	rdd->ctx.pos = 0;

	do {

	do {

		rdd->count = 0;

		rdd->count = 0;
@@ -274,7 +276,6 @@ static int ovl_dir_read_merged(struct dentry *dentry, struct list_head *list) 
		next = ovl_path_next(idx, dentry, &realpath);

		next = ovl_path_next(idx, dentry, &realpath);





		if (next != -1) {

		if (next != -1) {

			rdd.dir = realpath.dentry;

			err = ovl_dir_read(&realpath, &rdd);

			err = ovl_dir_read(&realpath, &rdd);

			if (err)

			if (err)

				break;

				break;

fs/overlayfs/super.c

+10 −17
Original line number Original line Diff line number Diff line
@@ -350,16 +350,12 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
		if (IS_ERR(this))

		if (IS_ERR(this))

			goto out;

			goto out;





		/*

		if (this) {

		 * If this is not the lowermost layer, check whiteout and opaque

		 * directory.

		 */

		if (poe->numlower && this) {

			if (ovl_is_whiteout(this)) {

			if (ovl_is_whiteout(this)) {

				dput(this);

				dput(this);

				this = NULL;

				this = NULL;

				upperopaque = true;

				upperopaque = true;

			} else if (ovl_is_opaquedir(this)) {

			} else if (poe->numlower && ovl_is_opaquedir(this)) {

				upperopaque = true;

				upperopaque = true;

			}

			}

		}

		}
@@ -384,19 +380,16 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			goto out_put;

			goto out_put;

		if (!this)

		if (!this)

			continue;

			continue;



		/*

		 * If this is not the lowermost layer, check whiteout and opaque

		 * directory.

		 */

		if (i < poe->numlower - 1) {

		if (ovl_is_whiteout(this)) {

		if (ovl_is_whiteout(this)) {

			dput(this);

			dput(this);

			break;

			break;

			} else if (ovl_is_opaquedir(this)) {

				opaque = true;

			}

		}

		}

		/*

		 * Only makes sense to check opaque dir if this is not the

		 * lowermost layer.

		 */

		if (i < poe->numlower - 1 && ovl_is_opaquedir(this))

			opaque = true;

		/*

		/*

		 * If this is a non-directory then stop here.

		 * If this is a non-directory then stop here.

		 *

		 *