[linux-2.6-block.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/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 "overlayfs.h"

#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)

int ovl_copy_xattr(struct dentry *old, struct dentry *new)
{
	ssize_t list_size, size;
	char *buf, *name, *value;
	int error;

	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;

	error = -ENOMEM;
	value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
	if (!value)
		goto out;

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

	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
		size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
		if (size <= 0) {
			error = size;
			goto out_free_value;
		}
		error = vfs_setxattr(new, name, value, size, 0);
		if (error)
			goto out_free_value;
	}

out_free_value:
	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_RDONLY);
	if (IS_ERR(old_file))
		return PTR_ERR(old_file);

	new_file = ovl_path_open(new, 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 char *ovl_read_symlink(struct dentry *realdentry)
{
	int res;
	char *buf;
	struct inode *inode = realdentry->d_inode;
	mm_segment_t old_fs;

	res = -EINVAL;
	if (!inode->i_op->readlink)
		goto err;

	res = -ENOMEM;
	buf = (char *) __get_free_page(GFP_KERNEL);
	if (!buf)
		goto err;

	old_fs = get_fs();
	set_fs(get_ds());
	/* The cast to a user pointer is valid due to the set_fs() */
	res = inode->i_op->readlink(realdentry,
				    (char __user *)buf, PAGE_SIZE - 1);
	set_fs(old_fs);
	if (res < 0) {
		free_page((unsigned long) buf);
		goto err;
	}
	buf[res] = '\0';

	return buf;

err:
	return ERR_PTR(res);
}

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, struct iattr *attr,
			      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;

	mutex_lock(&newdentry->d_inode->i_mutex);
	err = ovl_set_attr(newdentry, stat);
	if (!err && attr)
		err = notify_change(newdentry, attr, NULL);
	mutex_unlock(&newdentry->d_inode->i_mutex);
	if (err)
		goto out_cleanup;

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

	ovl_dentry_update(dentry, 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 out;
}

/*
 * 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,
		    struct iattr *attr)
{
	struct dentry *workdir = ovl_workdir(dentry);
	int err;
	struct kstat pstat;
	struct path parentpath;
	struct dentry *upperdir;
	struct dentry *upperdentry;
	const struct cred *old_cred;
	struct cred *override_cred;
	char *link = NULL;

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

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

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

	if (S_ISLNK(stat->mode)) {
		link = ovl_read_symlink(lowerpath->dentry);
		if (IS_ERR(link))
			return PTR_ERR(link);
	}

	err = -ENOMEM;
	override_cred = prepare_creds();
	if (!override_cred)
		goto out_free_link;

	override_cred->fsuid = stat->uid;
	override_cred->fsgid = stat->gid;
	/*
	 * CAP_SYS_ADMIN for copying up extended attributes
	 * CAP_DAC_OVERRIDE for create
	 * CAP_FOWNER for chmod, timestamp update
	 * CAP_FSETID for chmod
	 * CAP_CHOWN for chown
	 * CAP_MKNOD for mknod
	 */
	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
	cap_raise(override_cred->cap_effective, CAP_FOWNER);
	cap_raise(override_cred->cap_effective, CAP_FSETID);
	cap_raise(override_cred->cap_effective, CAP_CHOWN);
	cap_raise(override_cred->cap_effective, CAP_MKNOD);
	old_cred = override_creds(override_cred);

	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) {
		unlock_rename(workdir, upperdir);
		err = 0;
		/* Raced with another copy-up?  Do the setattr here */
		if (attr) {
			mutex_lock(&upperdentry->d_inode->i_mutex);
			err = notify_change(upperdentry, attr, NULL);
			mutex_unlock(&upperdentry->d_inode->i_mutex);
		}
		goto out_put_cred;
	}

	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
				 stat, attr, link);
	if (!err) {
		/* Restore timestamps on parent (best effort) */
		ovl_set_timestamps(upperdir, &pstat);
	}
out_unlock:
	unlock_rename(workdir, upperdir);
out_put_cred:
	revert_creds(old_cred);
	put_cred(override_cred);

out_free_link:
	if (link)
		free_page((unsigned long) link);

	return err;
}

int ovl_copy_up(struct dentry *dentry)
{
	int err;

	err = 0;
	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, NULL);

		dput(parent);
		dput(next);
	}

	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
	10	#include <linux/fs.h>
	11	#include <linux/slab.h>
	12	#include <linux/file.h>
	13	#include <linux/splice.h>
	14	#include <linux/xattr.h>
	15	#include <linux/security.h>
	16	#include <linux/uaccess.h>
	17	#include <linux/sched.h>
	18	#include <linux/namei.h>
	19	#include "overlayfs.h"
	20
	21	#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
	22
	23	int ovl_copy_xattr(struct dentry old, struct dentry new)
	24	{
	25	ssize_t list_size, size;
	26	char buf, name, *value;
	27	int error;
	28
	29	if (!old->d_inode->i_op->getxattr \|\|
	30	!new->d_inode->i_op->getxattr)
	31	return 0;
	32
	33	list_size = vfs_listxattr(old, NULL, 0);
	34	if (list_size <= 0) {
	35	if (list_size == -EOPNOTSUPP)
	36	return 0;
	37	return list_size;
	38	}
	39
	40	buf = kzalloc(list_size, GFP_KERNEL);
	41	if (!buf)
	42	return -ENOMEM;
	43
	44	error = -ENOMEM;
	45	value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);
	46	if (!value)
	47	goto out;
	48
	49	list_size = vfs_listxattr(old, buf, list_size);
	50	if (list_size <= 0) {
	51	error = list_size;
	52	goto out_free_value;
	53	}
	54
	55	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
	56	size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);
	57	if (size <= 0) {
	58	error = size;
	59	goto out_free_value;
	60	}
	61	error = vfs_setxattr(new, name, value, size, 0);
	62	if (error)
	63	goto out_free_value;
	64	}
65
66	out_free_value:
67	kfree(value);
68	out:
69	kfree(buf);
70	return error;
71	}
72
73	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
74	{
75	struct file *old_file;
76	struct file *new_file;
77	loff_t old_pos = 0;
78	loff_t new_pos = 0;
79	int error = 0;
80
81	if (len == 0)
82	return 0;
83
84	old_file = ovl_path_open(old, O_RDONLY);
85	if (IS_ERR(old_file))
86	return PTR_ERR(old_file);
87
88	new_file = ovl_path_open(new, O_WRONLY);
89	if (IS_ERR(new_file)) {
90	error = PTR_ERR(new_file);
91	goto out_fput;
92	}
93
94	/* FIXME: copy up sparse files efficiently */
95	while (len) {
96	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
97	long bytes;
98
99	if (len < this_len)
100	this_len = len;
101
102	if (signal_pending_state(TASK_KILLABLE, current)) {
103	error = -EINTR;
104	break;
105	}
106
107	bytes = do_splice_direct(old_file, &old_pos,
108	new_file, &new_pos,
109	this_len, SPLICE_F_MOVE);
110	if (bytes <= 0) {
111	error = bytes;
112	break;
113	}
114	WARN_ON(old_pos != new_pos);
115
116	len -= bytes;
117	}
118
119	fput(new_file);
120	out_fput:
121	fput(old_file);
122	return error;
123	}
124
125	static char ovl_read_symlink(struct dentry realdentry)
126	{
127	int res;
128	char *buf;
129	struct inode *inode = realdentry->d_inode;
130	mm_segment_t old_fs;
131
132	res = -EINVAL;
133	if (!inode->i_op->readlink)
134	goto err;
135
136	res = -ENOMEM;
137	buf = (char *) __get_free_page(GFP_KERNEL);
138	if (!buf)
139	goto err;
140
141	old_fs = get_fs();
142	set_fs(get_ds());
143	/* The cast to a user pointer is valid due to the set_fs() */
144	res = inode->i_op->readlink(realdentry,
145	(char __user *)buf, PAGE_SIZE - 1);
146	set_fs(old_fs);
147	if (res < 0) {
148	free_page((unsigned long) buf);
149	goto err;
150	}
151	buf[res] = '\0';
152
153	return buf;
154
155	err:
156	return ERR_PTR(res);
157	}
158
159	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
160	{
161	struct iattr attr = {
162	.ia_valid =
163	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
164	.ia_atime = stat->atime,
165	.ia_mtime = stat->mtime,
166	};
167
168	return notify_change(upperdentry, &attr, NULL);
169	}
170
171	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
172	{
173	int err = 0;
174
175	if (!S_ISLNK(stat->mode)) {
176	struct iattr attr = {
177	.ia_valid = ATTR_MODE,
178	.ia_mode = stat->mode,
179	};
180	err = notify_change(upperdentry, &attr, NULL);
181	}
182	if (!err) {
183	struct iattr attr = {
184	.ia_valid = ATTR_UID \| ATTR_GID,
185	.ia_uid = stat->uid,
186	.ia_gid = stat->gid,
187	};
188	err = notify_change(upperdentry, &attr, NULL);
189	}
190	if (!err)
191	ovl_set_timestamps(upperdentry, stat);
192
193	return err;
e9be9d5e MS	194	}
	195
	196	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	197	struct dentry dentry, struct path lowerpath,
	198	struct kstat stat, struct iattr attr,
	199	const char *link)
	200	{
	201	struct inode *wdir = workdir->d_inode;
	202	struct inode *udir = upperdir->d_inode;
	203	struct dentry *newdentry = NULL;
	204	struct dentry *upper = NULL;
	205	umode_t mode = stat->mode;
	206	int err;
	207
	208	newdentry = ovl_lookup_temp(workdir, dentry);
	209	err = PTR_ERR(newdentry);
	210	if (IS_ERR(newdentry))
	211	goto out;
	212
	213	upper = lookup_one_len(dentry->d_name.name, upperdir,
	214	dentry->d_name.len);
	215	err = PTR_ERR(upper);
	216	if (IS_ERR(upper))
	217	goto out1;
	218
	219	/* Can't properly set mode on creation because of the umask */
	220	stat->mode &= S_IFMT;
	221	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	222	stat->mode = mode;
	223	if (err)
	224	goto out2;
	225
	226	if (S_ISREG(stat->mode)) {
	227	struct path upperpath;
	228	ovl_path_upper(dentry, &upperpath);
	229	BUG_ON(upperpath.dentry != NULL);
	230	upperpath.dentry = newdentry;
	231
	232	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	233	if (err)
	234	goto out_cleanup;
	235	}
	236
	237	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	238	if (err)
	239	goto out_cleanup;
	240
	241	mutex_lock(&newdentry->d_inode->i_mutex);
	242	err = ovl_set_attr(newdentry, stat);
	243	if (!err && attr)
	244	err = notify_change(newdentry, attr, NULL);
	245	mutex_unlock(&newdentry->d_inode->i_mutex);
	246	if (err)
	247	goto out_cleanup;
	248
	249	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	250	if (err)
	251	goto out_cleanup;
	252
	253	ovl_dentry_update(dentry, newdentry);
	254	newdentry = NULL;
	255
	256	/*
	257	* Non-directores become opaque when copied up.
258	*/
259	if (!S_ISDIR(stat->mode))
260	ovl_dentry_set_opaque(dentry, true);
261	out2:
262	dput(upper);
263	out1:
264	dput(newdentry);
265	out:
266	return err;
267
268	out_cleanup:
269	ovl_cleanup(wdir, newdentry);
270	goto out;
271	}
272
273	/*
274	* Copy up a single dentry
275	*
276	* Directory renames only allowed on "pure upper" (already created on
277	* upper filesystem, never copied up). Directories which are on lower or
278	* are merged may not be renamed. For these -EXDEV is returned and
279	* userspace has to deal with it. This means, when copying up a
280	* directory we can rely on it and ancestors being stable.
281	*
282	* Non-directory renames start with copy up of source if necessary. The
283	* actual rename will only proceed once the copy up was successful. Copy
284	* up uses upper parent i_mutex for exclusion. Since rename can change
285	* d_parent it is possible that the copy up will lock the old parent. At
286	* that point the file will have already been copied up anyway.
287	*/
288	int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
289	struct path lowerpath, struct kstat stat,
290	struct iattr *attr)
291	{
292	struct dentry *workdir = ovl_workdir(dentry);
293	int err;
294	struct kstat pstat;
295	struct path parentpath;
296	struct dentry *upperdir;
297	struct dentry *upperdentry;
298	const struct cred *old_cred;
299	struct cred *override_cred;
300	char *link = NULL;
301
cc6f67bc MS	302	if (WARN_ON(!workdir))
	303	return -EROFS;
	304
e9be9d5e MS	305	ovl_path_upper(parent, &parentpath);
	306	upperdir = parentpath.dentry;
	307
	308	err = vfs_getattr(&parentpath, &pstat);
	309	if (err)
	310	return err;
	311
	312	if (S_ISLNK(stat->mode)) {
	313	link = ovl_read_symlink(lowerpath->dentry);
	314	if (IS_ERR(link))
	315	return PTR_ERR(link);
	316	}
	317
	318	err = -ENOMEM;
	319	override_cred = prepare_creds();
	320	if (!override_cred)
	321	goto out_free_link;
	322
	323	override_cred->fsuid = stat->uid;
	324	override_cred->fsgid = stat->gid;
	325	/*
	326	* CAP_SYS_ADMIN for copying up extended attributes
	327	* CAP_DAC_OVERRIDE for create
	328	* CAP_FOWNER for chmod, timestamp update
	329	* CAP_FSETID for chmod
	330	* CAP_CHOWN for chown
	331	* CAP_MKNOD for mknod
	332	*/
	333	cap_raise(override_cred->cap_effective, CAP_SYS_ADMIN);
	334	cap_raise(override_cred->cap_effective, CAP_DAC_OVERRIDE);
	335	cap_raise(override_cred->cap_effective, CAP_FOWNER);
	336	cap_raise(override_cred->cap_effective, CAP_FSETID);
	337	cap_raise(override_cred->cap_effective, CAP_CHOWN);
	338	cap_raise(override_cred->cap_effective, CAP_MKNOD);
	339	old_cred = override_creds(override_cred);
	340
	341	err = -EIO;
	342	if (lock_rename(workdir, upperdir) != NULL) {
	343	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	344	goto out_unlock;
	345	}
	346	upperdentry = ovl_dentry_upper(dentry);
	347	if (upperdentry) {
	348	unlock_rename(workdir, upperdir);
	349	err = 0;
	350	/* Raced with another copy-up? Do the setattr here */
	351	if (attr) {
	352	mutex_lock(&upperdentry->d_inode->i_mutex);
	353	err = notify_change(upperdentry, attr, NULL);
	354	mutex_unlock(&upperdentry->d_inode->i_mutex);
	355	}
	356	goto out_put_cred;
	357	}
	358
	359	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
	360	stat, attr, link);
	361	if (!err) {
	362	/* Restore timestamps on parent (best effort) */
	363	ovl_set_timestamps(upperdir, &pstat);
	364	}
	365	out_unlock:
	366	unlock_rename(workdir, upperdir);
	367	out_put_cred:
	368	revert_creds(old_cred);
369	put_cred(override_cred);
370
371	out_free_link:
372	if (link)
373	free_page((unsigned long) link);
374
375	return err;
376	}
377
378	int ovl_copy_up(struct dentry *dentry)
379	{
380	int err;
381
382	err = 0;
383	while (!err) {
384	struct dentry *next;
385	struct dentry *parent;
386	struct path lowerpath;
387	struct kstat stat;
388	enum ovl_path_type type = ovl_path_type(dentry);
389
1afaba1e	390	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	391	break;
	392
	393	next = dget(dentry);
	394	/* find the topmost dentry not yet copied up */
	395	for (;;) {
	396	parent = dget_parent(next);
	397
	398	type = ovl_path_type(parent);
1afaba1e	399	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	400	break;
	401
	402	dput(next);
	403	next = parent;
	404	}
	405
	406	ovl_path_lower(next, &lowerpath);
	407	err = vfs_getattr(&lowerpath, &stat);
	408	if (!err)
	409	err = ovl_copy_up_one(parent, next, &lowerpath, &stat, NULL);
	410
	411	dput(parent);
	412	dput(next);
	413	}
	414
	415	return err;
	416	}