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Commit 320cd413 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs 

Pull overlayfs updates from Miklos Szeredi:
 "This relaxes the requirements on the lower layer filesystem: now ones
  that implement .d_revalidate, such as NFS, can be used.

  Upper layer filesystems still has the "no .d_revalidate" requirement.

  Also a bad interaction with jffs2 locking has been fixed"

* 'overlayfs-next' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: lookup whiteouts outside iterate_dir()
  ovl: allow distributed fs as lower layer
  ovl: don't traverse automount points
parents a7ba4bf5 cdb67279

fs/overlayfs/readdir.c

+49 −28
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct ovl_cache_entry { 
	u64 ino;

	struct list_head l_node;

	struct rb_node node;

	struct ovl_cache_entry *next_maybe_whiteout;

	bool is_whiteout;

	char name[];

};
@@ -39,7 +40,7 @@ struct ovl_readdir_data { 
	struct rb_root root;

	struct list_head *list;

	struct list_head middle;

	struct dentry *dir;

	struct ovl_cache_entry *first_maybe_whiteout;

	int count;

	int err;

};
@@ -79,7 +80,7 @@ static struct ovl_cache_entry *ovl_cache_entry_find(struct rb_root *root, 
	return NULL;

}



static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir,

static struct ovl_cache_entry *ovl_cache_entry_new(struct ovl_readdir_data *rdd,

						   const char *name, int len,

						   u64 ino, unsigned int d_type)

{
@@ -98,29 +99,8 @@ static struct ovl_cache_entry *ovl_cache_entry_new(struct dentry *dir, 
	p->is_whiteout = 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);

		p->next_maybe_whiteout = rdd->first_maybe_whiteout;

		rdd->first_maybe_whiteout = p;

	}

	return p;

}
@@ -148,7 +128,7 @@ static int ovl_cache_entry_add_rb(struct ovl_readdir_data *rdd, 
			return 0;

	}



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

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

	if (p == NULL)

		return -ENOMEM;
@@ -169,7 +149,7 @@ static int ovl_fill_lower(struct ovl_readdir_data *rdd, 
	if (p) {

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

	} else {

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

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

		if (p == NULL)

			rdd->err = -ENOMEM;

		else
@@ -219,6 +199,43 @@ static int ovl_fill_merge(struct dir_context *ctx, const char *name, 
		return ovl_fill_lower(rdd, name, namelen, offset, ino, d_type);

}



static int ovl_check_whiteouts(struct dentry *dir, struct ovl_readdir_data *rdd)

{

	int err;

	struct ovl_cache_entry *p;

	struct dentry *dentry;

	const struct cred *old_cred;

	struct cred *override_cred;



	override_cred = prepare_creds();

	if (!override_cred)

		return -ENOMEM;



	/*

	 * CAP_DAC_OVERRIDE for lookup

	 */

	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);

	old_cred = override_creds(override_cred);



	err = mutex_lock_killable(&dir->d_inode->i_mutex);

	if (!err) {

		while (rdd->first_maybe_whiteout) {

			p = rdd->first_maybe_whiteout;

			rdd->first_maybe_whiteout = p->next_maybe_whiteout;

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

			if (!IS_ERR(dentry)) {

				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 err;

}



static inline int ovl_dir_read(struct path *realpath,

			       struct ovl_readdir_data *rdd)

{
@@ -229,7 +246,7 @@ static inline int ovl_dir_read(struct path *realpath, 
	if (IS_ERR(realfile))

		return PTR_ERR(realfile);



	rdd->dir = realpath->dentry;

	rdd->first_maybe_whiteout = NULL;

	rdd->ctx.pos = 0;

	do {

		rdd->count = 0;
@@ -238,6 +255,10 @@ static inline int ovl_dir_read(struct path *realpath, 
		if (err >= 0)

			err = rdd->err;

	} while (!err && rdd->count);



	if (!err && rdd->first_maybe_whiteout)

		err = ovl_check_whiteouts(realpath->dentry, rdd);



	fput(realfile);



	return err;

fs/overlayfs/super.c

+90 −23
Original line number Diff line number Diff line
@@ -273,10 +273,57 @@ static void ovl_dentry_release(struct dentry *dentry) 
	}

}



static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags)

{

	struct ovl_entry *oe = dentry->d_fsdata;

	unsigned int i;

	int ret = 1;



	for (i = 0; i < oe->numlower; i++) {

		struct dentry *d = oe->lowerstack[i].dentry;



		if (d->d_flags & DCACHE_OP_REVALIDATE) {

			ret = d->d_op->d_revalidate(d, flags);

			if (ret < 0)

				return ret;

			if (!ret) {

				if (!(flags & LOOKUP_RCU))

					d_invalidate(d);

				return -ESTALE;

			}

		}

	}

	return 1;

}



static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags)

{

	struct ovl_entry *oe = dentry->d_fsdata;

	unsigned int i;

	int ret = 1;



	for (i = 0; i < oe->numlower; i++) {

		struct dentry *d = oe->lowerstack[i].dentry;



		if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) {

			ret = d->d_op->d_weak_revalidate(d, flags);

			if (ret <= 0)

				break;

		}

	}

	return ret;

}



static const struct dentry_operations ovl_dentry_operations = {

	.d_release = ovl_dentry_release,

};



static const struct dentry_operations ovl_reval_dentry_operations = {

	.d_release = ovl_dentry_release,

	.d_revalidate = ovl_dentry_revalidate,

	.d_weak_revalidate = ovl_dentry_weak_revalidate,

};



static struct ovl_entry *ovl_alloc_entry(unsigned int numlower)

{

	size_t size = offsetof(struct ovl_entry, lowerstack[numlower]);
@@ -288,6 +335,20 @@ static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) 
	return oe;

}



static bool ovl_dentry_remote(struct dentry *dentry)

{

	return dentry->d_flags &

		(DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE);

}



static bool ovl_dentry_weird(struct dentry *dentry)

{

	return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT |

				  DCACHE_MANAGE_TRANSIT |

				  DCACHE_OP_HASH |

				  DCACHE_OP_COMPARE);

}



static inline struct dentry *ovl_lookup_real(struct dentry *dir,

					     struct qstr *name)

{
@@ -303,6 +364,10 @@ static inline struct dentry *ovl_lookup_real(struct dentry *dir, 
	} else if (!dentry->d_inode) {

		dput(dentry);

		dentry = NULL;

	} else if (ovl_dentry_weird(dentry)) {

		dput(dentry);

		/* Don't support traversing automounts and other weirdness */

		dentry = ERR_PTR(-EREMOTE);

	}

	return dentry;

}
@@ -350,6 +415,11 @@ struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, 
			goto out;



		if (this) {

			if (unlikely(ovl_dentry_remote(this))) {

				dput(this);

				err = -EREMOTE;

				goto out;

			}

			if (ovl_is_whiteout(this)) {

				dput(this);

				this = NULL;
@@ -694,25 +764,6 @@ static void ovl_unescape(char *s) 
	}

}



static bool ovl_is_allowed_fs_type(struct dentry *root)

{

	const struct dentry_operations *dop = root->d_op;



	/*

	 * We don't support:

	 *  - automount filesystems

	 *  - filesystems with revalidate (FIXME for lower layer)

	 *  - filesystems with case insensitive names

	 */

	if (dop &&

	    (dop->d_manage || dop->d_automount ||

	     dop->d_revalidate || dop->d_weak_revalidate ||

	     dop->d_compare || dop->d_hash)) {

		return false;

	}

	return true;

}



static int ovl_mount_dir_noesc(const char *name, struct path *path)

{

	int err = -EINVAL;
@@ -727,7 +778,7 @@ static int ovl_mount_dir_noesc(const char *name, struct path *path) 
		goto out;

	}

	err = -EINVAL;

	if (!ovl_is_allowed_fs_type(path->dentry)) {

	if (ovl_dentry_weird(path->dentry)) {

		pr_err("overlayfs: filesystem on '%s' not supported\n", name);

		goto out_put;

	}
@@ -751,13 +802,21 @@ static int ovl_mount_dir(const char *name, struct path *path) 
	if (tmp) {

		ovl_unescape(tmp);

		err = ovl_mount_dir_noesc(tmp, path);



		if (!err)

			if (ovl_dentry_remote(path->dentry)) {

				pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n",

				       tmp);

				path_put(path);

				err = -EINVAL;

			}

		kfree(tmp);

	}

	return err;

}



static int ovl_lower_dir(const char *name, struct path *path, long *namelen,

			 int *stack_depth)

			 int *stack_depth, bool *remote)

{

	int err;

	struct kstatfs statfs;
@@ -774,6 +833,9 @@ static int ovl_lower_dir(const char *name, struct path *path, long *namelen, 
	*namelen = max(*namelen, statfs.f_namelen);

	*stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth);



	if (ovl_dentry_remote(path->dentry))

		*remote = true;



	return 0;



out_put:
@@ -827,6 +889,7 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	unsigned int numlower;

	unsigned int stacklen = 0;

	unsigned int i;

	bool remote = false;

	int err;



	err = -ENOMEM;
@@ -900,7 +963,8 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	lower = lowertmp;

	for (numlower = 0; numlower < stacklen; numlower++) {

		err = ovl_lower_dir(lower, &stack[numlower],

				    &ufs->lower_namelen, &sb->s_stack_depth);

				    &ufs->lower_namelen, &sb->s_stack_depth,

				    &remote);

		if (err)

			goto out_put_lowerpath;
@@ -958,6 +1022,9 @@ static int ovl_fill_super(struct super_block *sb, void *data, int silent) 
	if (!ufs->upper_mnt)

		sb->s_flags |= MS_RDONLY;



	if (remote)

		sb->s_d_op = &ovl_reval_dentry_operations;

	else

		sb->s_d_op = &ovl_dentry_operations;



	err = -ENOMEM;