[mirror_ubuntu-zesty-kernel.git] / fs / overlayfs / copy_up.c

/*
 *
 * Copyright (C) 2011 Novell Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/splice.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <linux/fdtable.h>
#include <linux/ratelimit.h>
#include "overlayfs.h"

#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)

static bool __read_mostly ovl_check_copy_up;
module_param_named(check_copy_up, ovl_check_copy_up, bool,
		   S_IWUSR | S_IRUGO);
MODULE_PARM_DESC(ovl_check_copy_up,
		 "Warn on copy-up when causing process also has a R/O fd open");

static int ovl_check_fd(const void *data, struct file *f, unsigned int fd)
{
	const struct dentry *dentry = data;

	if (f->f_inode == d_inode(dentry))
		pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
				    f, fd, current->pid, current->comm);
	return 0;
}

/*
 * Check the fds open by this process and warn if something like the following
 * scenario is about to occur:
 *
 *	fd1 = open("foo", O_RDONLY);
 *	fd2 = open("foo", O_RDWR);
 */
static void ovl_do_check_copy_up(struct dentry *dentry)
{
	if (ovl_check_copy_up)
		iterate_fd(current->files, 0, ovl_check_fd, dentry);
}

int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
	ssize_t list_size, size, value_size = 0;
	char *buf, *name, *value = NULL;
	int uninitialized_var(error);
	size_t slen;

	if (!old->d_inode->i_op->getxattr ||
	    !new->d_inode->i_op->getxattr)
		return 0;

	list_size = vfs_listxattr(old, NULL, 0);
	if (list_size <= 0) {
		if (list_size == -EOPNOTSUPP)
			return 0;
		return list_size;
	}

	buf = kzalloc(list_size, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	list_size = vfs_listxattr(old, buf, list_size);
	if (list_size <= 0) {
		error = list_size;
		goto out;
	}

	for (name = buf; list_size; name += slen) {
		slen = strnlen(name, list_size) + 1;

		/* underlying fs providing us with an broken xattr list? */
		if (WARN_ON(slen > list_size)) {
			error = -EIO;
			break;
		}
		list_size -= slen;

		if (ovl_is_private_xattr(name))
			continue;
retry:
		size = vfs_getxattr(old, name, value, value_size);
		if (size == -ERANGE)
			size = vfs_getxattr(old, name, NULL, 0);

		if (size < 0) {
			error = size;
			break;
		}

		if (size > value_size) {
			void *new;

			new = krealloc(value, size, GFP_KERNEL);
			if (!new) {
				error = -ENOMEM;
				break;
			}
			value = new;
			value_size = size;
			goto retry;
		}

		error = vfs_setxattr(new, name, value, size, 0);
		if (error)
			break;
	}
	kfree(value);
out:
	kfree(buf);
	return error;
}

static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
{
	struct file *old_file;
	struct file *new_file;
	loff_t old_pos = 0;
	loff_t new_pos = 0;
	int error = 0;

	if (len == 0)
		return 0;

	old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
	if (IS_ERR(old_file))
		return PTR_ERR(old_file);

	new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
	if (IS_ERR(new_file)) {
		error = PTR_ERR(new_file);
		goto out_fput;
	}

	/* FIXME: copy up sparse files efficiently */
	while (len) {
		size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
		long bytes;

		if (len < this_len)
			this_len = len;

		if (signal_pending_state(TASK_KILLABLE, current)) {
			error = -EINTR;
			break;
		}

		bytes = do_splice_direct(old_file, &old_pos,
					 new_file, &new_pos,
					 this_len, SPLICE_F_MOVE);
		if (bytes <= 0) {
			error = bytes;
			break;
		}
		WARN_ON(old_pos != new_pos);

		len -= bytes;
	}

	fput(new_file);
out_fput:
	fput(old_file);
	return error;
}

static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
{
	struct iattr attr = {
		.ia_valid =
		     ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
		.ia_atime = stat->atime,
		.ia_mtime = stat->mtime,
	};

	return notify_change(upperdentry, &attr, NULL);
}

int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
{
	int err = 0;

	if (!S_ISLNK(stat->mode)) {
		struct iattr attr = {
			.ia_valid = ATTR_MODE,
			.ia_mode = stat->mode,
		};
		err = notify_change(upperdentry, &attr, NULL);
	}
	if (!err) {
		struct iattr attr = {
			.ia_valid = ATTR_UID | ATTR_GID,
			.ia_uid = stat->uid,
			.ia_gid = stat->gid,
		};
		err = notify_change(upperdentry, &attr, NULL);
	}
	if (!err)
		ovl_set_timestamps(upperdentry, stat);

	return err;
}

static int ovl_copy_up_locked(struct dentry *workdir, struct dentry *upperdir,
			      struct dentry *dentry, struct path *lowerpath,
			      struct kstat *stat, const char *link)
{
	struct inode *wdir = workdir->d_inode;
	struct inode *udir = upperdir->d_inode;
	struct dentry *newdentry = NULL;
	struct dentry *upper = NULL;
	umode_t mode = stat->mode;
	int err;

	newdentry = ovl_lookup_temp(workdir, dentry);
	err = PTR_ERR(newdentry);
	if (IS_ERR(newdentry))
		goto out;

	upper = lookup_one_len(dentry->d_name.name, upperdir,
			       dentry->d_name.len);
	err = PTR_ERR(upper);
	if (IS_ERR(upper))
		goto out1;

	/* Can't properly set mode on creation because of the umask */
	stat->mode &= S_IFMT;
	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	stat->mode = mode;
	if (err)
		goto out2;

	if (S_ISREG(stat->mode)) {
		struct path upperpath;

		ovl_path_upper(dentry, &upperpath);
		BUG_ON(upperpath.dentry != NULL);
		upperpath.dentry = newdentry;

		err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
		if (err)
			goto out_cleanup;
	}

	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	if (err)
		goto out_cleanup;

	inode_lock(newdentry->d_inode);
	err = ovl_set_attr(newdentry, stat);
	inode_unlock(newdentry->d_inode);
	if (err)
		goto out_cleanup;

	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	if (err)
		goto out_cleanup;

	ovl_dentry_update(dentry, newdentry);
	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
	newdentry = NULL;

	/*
	 * Non-directores become opaque when copied up.
	 */
	if (!S_ISDIR(stat->mode))
		ovl_dentry_set_opaque(dentry, true);
out2:
	dput(upper);
out1:
	dput(newdentry);
out:
	return err;

out_cleanup:
	ovl_cleanup(wdir, newdentry);
	goto out2;
}

/*
 * Copy up a single dentry
 *
 * Directory renames only allowed on "pure upper" (already created on
 * upper filesystem, never copied up).  Directories which are on lower or
 * are merged may not be renamed.  For these -EXDEV is returned and
 * userspace has to deal with it.  This means, when copying up a
 * directory we can rely on it and ancestors being stable.
 *
 * Non-directory renames start with copy up of source if necessary.  The
 * actual rename will only proceed once the copy up was successful.  Copy
 * up uses upper parent i_mutex for exclusion.  Since rename can change
 * d_parent it is possible that the copy up will lock the old parent.  At
 * that point the file will have already been copied up anyway.
 */
int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
		    struct path *lowerpath, struct kstat *stat)
{
	DEFINE_DELAYED_CALL(done);
	struct dentry *workdir = ovl_workdir(dentry);
	int err;
	struct kstat pstat;
	struct path parentpath;
	struct dentry *lowerdentry = lowerpath->dentry;
	struct dentry *upperdir;
	struct dentry *upperdentry;
	const char *link = NULL;

	if (WARN_ON(!workdir))
		return -EROFS;

	ovl_do_check_copy_up(lowerdentry);

	ovl_path_upper(parent, &parentpath);
	upperdir = parentpath.dentry;

	err = vfs_getattr(&parentpath, &pstat);
	if (err)
		return err;

	if (S_ISLNK(stat->mode)) {
		link = vfs_get_link(lowerdentry, &done);
		if (IS_ERR(link))
			return PTR_ERR(link);
	}

	err = -EIO;
	if (lock_rename(workdir, upperdir) != NULL) {
		pr_err("overlayfs: failed to lock workdir+upperdir\n");
		goto out_unlock;
	}
	upperdentry = ovl_dentry_upper(dentry);
	if (upperdentry) {
		/* Raced with another copy-up?  Nothing to do, then... */
		err = 0;
		goto out_unlock;
	}

	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
				 stat, link);
	if (!err) {
		/* Restore timestamps on parent (best effort) */
		ovl_set_timestamps(upperdir, &pstat);
	}
out_unlock:
	unlock_rename(workdir, upperdir);
	do_delayed_call(&done);

	return err;
}

int ovl_copy_up(struct dentry *dentry)
{
	int err = 0;
	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);

	while (!err) {
		struct dentry *next;
		struct dentry *parent;
		struct path lowerpath;
		struct kstat stat;
		enum ovl_path_type type = ovl_path_type(dentry);

		if (OVL_TYPE_UPPER(type))
			break;

		next = dget(dentry);
		/* find the topmost dentry not yet copied up */
		for (;;) {
			parent = dget_parent(next);

			type = ovl_path_type(parent);
			if (OVL_TYPE_UPPER(type))
				break;

			dput(next);
			next = parent;
		}

		ovl_path_lower(next, &lowerpath);
		err = vfs_getattr(&lowerpath, &stat);
		if (!err)
			err = ovl_copy_up_one(parent, next, &lowerpath, &stat);

		dput(parent);
		dput(next);
	}
	revert_creds(old_cred);

	return err;
}
Commit	Line	Data
e9be9d5e MS	1	/*
	2	*
	3	* Copyright (C) 2011 Novell Inc.
	4	*
	5	* This program is free software; you can redistribute it and/or modify it
	6	* under the terms of the GNU General Public License version 2 as published by
	7	* the Free Software Foundation.
	8	*/
	9
fb5bb2c3	10	#include <linux/module.h>
e9be9d5e MS	11	#include <linux/fs.h>
	12	#include <linux/slab.h>
	13	#include <linux/file.h>
	14	#include <linux/splice.h>
	15	#include <linux/xattr.h>
	16	#include <linux/security.h>
	17	#include <linux/uaccess.h>
	18	#include <linux/sched.h>
	19	#include <linux/namei.h>
fb5bb2c3 DH	20	#include <linux/fdtable.h>
fb5bb2c3 DH	21	#include <linux/ratelimit.h>
e9be9d5e MS	22	#include "overlayfs.h"
	23
	24	#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
	25
fb5bb2c3 DH	26	static bool __read_mostly ovl_check_copy_up;
	27	module_param_named(check_copy_up, ovl_check_copy_up, bool,
	28	S_IWUSR \| S_IRUGO);
	29	MODULE_PARM_DESC(ovl_check_copy_up,
	30	"Warn on copy-up when causing process also has a R/O fd open");
	31
	32	static int ovl_check_fd(const void data, struct file f, unsigned int fd)
	33	{
	34	const struct dentry *dentry = data;
	35
	36	if (f->f_inode == d_inode(dentry))
	37	pr_warn_ratelimited("overlayfs: Warning: Copying up %pD, but open R/O on fd %u which will cease to be coherent [pid=%d %s]\n",
	38	f, fd, current->pid, current->comm);
	39	return 0;
	40	}
	41
	42	/*
	43	* Check the fds open by this process and warn if something like the following
	44	* scenario is about to occur:
	45	*
	46	* fd1 = open("foo", O_RDONLY);
	47	* fd2 = open("foo", O_RDWR);
	48	*/
	49	static void ovl_do_check_copy_up(struct dentry *dentry)
	50	{
	51	if (ovl_check_copy_up)
	52	iterate_fd(current->files, 0, ovl_check_fd, dentry);
	53	}
	54
e9be9d5e MS	55	int ovl_copy_xattr(struct dentry old, struct dentry new)
e9be9d5e MS	56	{
e4ad29fa VC	57	ssize_t list_size, size, value_size = 0;
	58	char buf, name, *value = NULL;
	59	int uninitialized_var(error);
8b326c61	60	size_t slen;
e9be9d5e MS	61
	62	if (!old->d_inode->i_op->getxattr \|\|
	63	!new->d_inode->i_op->getxattr)
	64	return 0;
	65
	66	list_size = vfs_listxattr(old, NULL, 0);
	67	if (list_size <= 0) {
	68	if (list_size == -EOPNOTSUPP)
	69	return 0;
	70	return list_size;
	71	}
	72
	73	buf = kzalloc(list_size, GFP_KERNEL);
	74	if (!buf)
	75	return -ENOMEM;
	76
e9be9d5e MS	77	list_size = vfs_listxattr(old, buf, list_size);
	78	if (list_size <= 0) {
	79	error = list_size;
e4ad29fa	80	goto out;
e9be9d5e MS	81	}
e9be9d5e MS	82
8b326c61 MS	83	for (name = buf; list_size; name += slen) {
	84	slen = strnlen(name, list_size) + 1;
	85
	86	/* underlying fs providing us with an broken xattr list? */
	87	if (WARN_ON(slen > list_size)) {
	88	error = -EIO;
	89	break;
	90	}
	91	list_size -= slen;
	92
0956254a MS	93	if (ovl_is_private_xattr(name))
0956254a MS	94	continue;
e4ad29fa VC	95	retry:
	96	size = vfs_getxattr(old, name, value, value_size);
	97	if (size == -ERANGE)
	98	size = vfs_getxattr(old, name, NULL, 0);
	99
97daf8b9	100	if (size < 0) {
e9be9d5e	101	error = size;
e4ad29fa	102	break;
e9be9d5e	103	}
e4ad29fa VC	104
	105	if (size > value_size) {
	106	void *new;
	107
	108	new = krealloc(value, size, GFP_KERNEL);
	109	if (!new) {
	110	error = -ENOMEM;
	111	break;
	112	}
	113	value = new;
	114	value_size = size;
	115	goto retry;
	116	}
	117
e9be9d5e MS	118	error = vfs_setxattr(new, name, value, size, 0);
e9be9d5e MS	119	if (error)
e4ad29fa	120	break;
e9be9d5e	121	}
e9be9d5e MS	122	kfree(value);
	123	out:
	124	kfree(buf);
	125	return error;
	126	}
	127
	128	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
	129	{
	130	struct file *old_file;
	131	struct file *new_file;
	132	loff_t old_pos = 0;
	133	loff_t new_pos = 0;
	134	int error = 0;
	135
	136	if (len == 0)
	137	return 0;
	138
0480334f	139	old_file = ovl_path_open(old, O_LARGEFILE \| O_RDONLY);
e9be9d5e MS	140	if (IS_ERR(old_file))
	141	return PTR_ERR(old_file);
	142
0480334f	143	new_file = ovl_path_open(new, O_LARGEFILE \| O_WRONLY);
e9be9d5e MS	144	if (IS_ERR(new_file)) {
	145	error = PTR_ERR(new_file);
	146	goto out_fput;
	147	}
	148
	149	/* FIXME: copy up sparse files efficiently */
	150	while (len) {
	151	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
	152	long bytes;
	153
	154	if (len < this_len)
	155	this_len = len;
	156
	157	if (signal_pending_state(TASK_KILLABLE, current)) {
	158	error = -EINTR;
	159	break;
	160	}
	161
	162	bytes = do_splice_direct(old_file, &old_pos,
	163	new_file, &new_pos,
	164	this_len, SPLICE_F_MOVE);
	165	if (bytes <= 0) {
	166	error = bytes;
	167	break;
	168	}
	169	WARN_ON(old_pos != new_pos);
	170
	171	len -= bytes;
	172	}
	173
	174	fput(new_file);
	175	out_fput:
	176	fput(old_file);
	177	return error;
	178	}
	179
e9be9d5e MS	180	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
	181	{
	182	struct iattr attr = {
	183	.ia_valid =
	184	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
	185	.ia_atime = stat->atime,
	186	.ia_mtime = stat->mtime,
	187	};
	188
	189	return notify_change(upperdentry, &attr, NULL);
	190	}
	191
	192	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
	193	{
	194	int err = 0;
	195
	196	if (!S_ISLNK(stat->mode)) {
	197	struct iattr attr = {
	198	.ia_valid = ATTR_MODE,
	199	.ia_mode = stat->mode,
	200	};
	201	err = notify_change(upperdentry, &attr, NULL);
	202	}
	203	if (!err) {
	204	struct iattr attr = {
	205	.ia_valid = ATTR_UID \| ATTR_GID,
	206	.ia_uid = stat->uid,
	207	.ia_gid = stat->gid,
	208	};
	209	err = notify_change(upperdentry, &attr, NULL);
	210	}
	211	if (!err)
	212	ovl_set_timestamps(upperdentry, stat);
	213
	214	return err;
e9be9d5e MS	215	}
	216
	217	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	218	struct dentry dentry, struct path lowerpath,
0f7ff2da	219	struct kstat stat, const char link)
e9be9d5e MS	220	{
	221	struct inode *wdir = workdir->d_inode;
	222	struct inode *udir = upperdir->d_inode;
	223	struct dentry *newdentry = NULL;
	224	struct dentry *upper = NULL;
	225	umode_t mode = stat->mode;
	226	int err;
	227
	228	newdentry = ovl_lookup_temp(workdir, dentry);
	229	err = PTR_ERR(newdentry);
	230	if (IS_ERR(newdentry))
	231	goto out;
	232
	233	upper = lookup_one_len(dentry->d_name.name, upperdir,
	234	dentry->d_name.len);
	235	err = PTR_ERR(upper);
	236	if (IS_ERR(upper))
	237	goto out1;
	238
	239	/* Can't properly set mode on creation because of the umask */
	240	stat->mode &= S_IFMT;
	241	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	242	stat->mode = mode;
	243	if (err)
	244	goto out2;
	245
	246	if (S_ISREG(stat->mode)) {
	247	struct path upperpath;
f134f244	248
e9be9d5e MS	249	ovl_path_upper(dentry, &upperpath);
	250	BUG_ON(upperpath.dentry != NULL);
	251	upperpath.dentry = newdentry;
	252
	253	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	254	if (err)
	255	goto out_cleanup;
	256	}
	257
	258	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	259	if (err)
	260	goto out_cleanup;
	261
5955102c	262	inode_lock(newdentry->d_inode);
e9be9d5e	263	err = ovl_set_attr(newdentry, stat);
5955102c	264	inode_unlock(newdentry->d_inode);
e9be9d5e MS	265	if (err)
	266	goto out_cleanup;
	267
	268	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	269	if (err)
	270	goto out_cleanup;
	271
	272	ovl_dentry_update(dentry, newdentry);
39b681f8	273	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
e9be9d5e MS	274	newdentry = NULL;
	275
	276	/*
	277	* Non-directores become opaque when copied up.
	278	*/
	279	if (!S_ISDIR(stat->mode))
	280	ovl_dentry_set_opaque(dentry, true);
	281	out2:
	282	dput(upper);
	283	out1:
	284	dput(newdentry);
	285	out:
	286	return err;
	287
	288	out_cleanup:
	289	ovl_cleanup(wdir, newdentry);
ab79efab	290	goto out2;
e9be9d5e MS	291	}
	292
	293	/*
	294	* Copy up a single dentry
	295	*
	296	* Directory renames only allowed on "pure upper" (already created on
	297	* upper filesystem, never copied up). Directories which are on lower or
	298	* are merged may not be renamed. For these -EXDEV is returned and
	299	* userspace has to deal with it. This means, when copying up a
	300	* directory we can rely on it and ancestors being stable.
	301	*
	302	* Non-directory renames start with copy up of source if necessary. The
	303	* actual rename will only proceed once the copy up was successful. Copy
	304	* up uses upper parent i_mutex for exclusion. Since rename can change
	305	* d_parent it is possible that the copy up will lock the old parent. At
	306	* that point the file will have already been copied up anyway.
	307	*/
	308	int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
0f7ff2da	309	struct path lowerpath, struct kstat stat)
e9be9d5e	310	{
7764235b	311	DEFINE_DELAYED_CALL(done);
e9be9d5e MS	312	struct dentry *workdir = ovl_workdir(dentry);
	313	int err;
	314	struct kstat pstat;
	315	struct path parentpath;
7764235b	316	struct dentry *lowerdentry = lowerpath->dentry;
e9be9d5e MS	317	struct dentry *upperdir;
e9be9d5e MS	318	struct dentry *upperdentry;
7764235b	319	const char *link = NULL;
e9be9d5e	320
cc6f67bc MS	321	if (WARN_ON(!workdir))
	322	return -EROFS;
	323
7764235b	324	ovl_do_check_copy_up(lowerdentry);
fb5bb2c3	325
e9be9d5e MS	326	ovl_path_upper(parent, &parentpath);
	327	upperdir = parentpath.dentry;
	328
	329	err = vfs_getattr(&parentpath, &pstat);
	330	if (err)
	331	return err;
	332
	333	if (S_ISLNK(stat->mode)) {
7764235b	334	link = vfs_get_link(lowerdentry, &done);
e9be9d5e MS	335	if (IS_ERR(link))
	336	return PTR_ERR(link);
	337	}
	338
e9be9d5e MS	339	err = -EIO;
	340	if (lock_rename(workdir, upperdir) != NULL) {
	341	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	342	goto out_unlock;
	343	}
	344	upperdentry = ovl_dentry_upper(dentry);
	345	if (upperdentry) {
0f7ff2da	346	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	347	err = 0;
0f7ff2da	348	goto out_unlock;
e9be9d5e MS	349	}
	350
	351	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
0f7ff2da	352	stat, link);
e9be9d5e MS	353	if (!err) {
	354	/* Restore timestamps on parent (best effort) */
	355	ovl_set_timestamps(upperdir, &pstat);
	356	}
	357	out_unlock:
	358	unlock_rename(workdir, upperdir);
7764235b	359	do_delayed_call(&done);
e9be9d5e MS	360
	361	return err;
	362	}
	363
	364	int ovl_copy_up(struct dentry *dentry)
	365	{
8eac98b8 VG	366	int err = 0;
8eac98b8 VG	367	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	368
e9be9d5e MS	369	while (!err) {
	370	struct dentry *next;
	371	struct dentry *parent;
	372	struct path lowerpath;
	373	struct kstat stat;
	374	enum ovl_path_type type = ovl_path_type(dentry);
	375
1afaba1e	376	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	377	break;
	378
	379	next = dget(dentry);
	380	/* find the topmost dentry not yet copied up */
	381	for (;;) {
	382	parent = dget_parent(next);
	383
	384	type = ovl_path_type(parent);
1afaba1e	385	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	386	break;
	387
	388	dput(next);
	389	next = parent;
	390	}
	391
	392	ovl_path_lower(next, &lowerpath);
	393	err = vfs_getattr(&lowerpath, &stat);
	394	if (!err)
0f7ff2da	395	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	396
	397	dput(parent);
	398	dput(next);
	399	}
8eac98b8	400	revert_creds(old_cred);
e9be9d5e MS	401
	402	return err;
	403	}