[mirror_ubuntu-artful-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 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, 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)
{
	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;
	char *link = NULL;

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

	ovl_do_check_copy_up(lowerpath->dentry);

	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);
	}

	old_cred = ovl_override_creds(dentry->d_sb);

	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);
	revert_creds(old_cred);

	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);

		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
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
	180	static char ovl_read_symlink(struct dentry realdentry)
	181	{
	182	int res;
	183	char *buf;
	184	struct inode *inode = realdentry->d_inode;
	185	mm_segment_t old_fs;
	186
	187	res = -EINVAL;
	188	if (!inode->i_op->readlink)
	189	goto err;
	190
	191	res = -ENOMEM;
	192	buf = (char *) __get_free_page(GFP_KERNEL);
	193	if (!buf)
	194	goto err;
	195
	196	old_fs = get_fs();
	197	set_fs(get_ds());
	198	/* The cast to a user pointer is valid due to the set_fs() */
	199	res = inode->i_op->readlink(realdentry,
	200	(char __user *)buf, PAGE_SIZE - 1);
	201	set_fs(old_fs);
	202	if (res < 0) {
	203	free_page((unsigned long) buf);
	204	goto err;
	205	}
	206	buf[res] = '\0';
	207
208	return buf;
209
210	err:
211	return ERR_PTR(res);
212	}
213
214	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
215	{
216	struct iattr attr = {
217	.ia_valid =
218	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
219	.ia_atime = stat->atime,
220	.ia_mtime = stat->mtime,
221	};
222
223	return notify_change(upperdentry, &attr, NULL);
224	}
225
226	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
227	{
228	int err = 0;
229
230	if (!S_ISLNK(stat->mode)) {
231	struct iattr attr = {
232	.ia_valid = ATTR_MODE,
233	.ia_mode = stat->mode,
234	};
235	err = notify_change(upperdentry, &attr, NULL);
236	}
237	if (!err) {
238	struct iattr attr = {
239	.ia_valid = ATTR_UID \| ATTR_GID,
240	.ia_uid = stat->uid,
241	.ia_gid = stat->gid,
242	};
243	err = notify_change(upperdentry, &attr, NULL);
244	}
245	if (!err)
246	ovl_set_timestamps(upperdentry, stat);
247
248	return err;
e9be9d5e MS	249	}
	250
	251	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	252	struct dentry dentry, struct path lowerpath,
0f7ff2da	253	struct kstat stat, const char link)
e9be9d5e MS	254	{
	255	struct inode *wdir = workdir->d_inode;
	256	struct inode *udir = upperdir->d_inode;
	257	struct dentry *newdentry = NULL;
	258	struct dentry *upper = NULL;
	259	umode_t mode = stat->mode;
	260	int err;
	261
	262	newdentry = ovl_lookup_temp(workdir, dentry);
	263	err = PTR_ERR(newdentry);
	264	if (IS_ERR(newdentry))
	265	goto out;
	266
	267	upper = lookup_one_len(dentry->d_name.name, upperdir,
	268	dentry->d_name.len);
	269	err = PTR_ERR(upper);
	270	if (IS_ERR(upper))
	271	goto out1;
	272
	273	/* Can't properly set mode on creation because of the umask */
	274	stat->mode &= S_IFMT;
	275	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	276	stat->mode = mode;
	277	if (err)
	278	goto out2;
	279
	280	if (S_ISREG(stat->mode)) {
	281	struct path upperpath;
f134f244	282
e9be9d5e MS	283	ovl_path_upper(dentry, &upperpath);
	284	BUG_ON(upperpath.dentry != NULL);
	285	upperpath.dentry = newdentry;
	286
	287	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	288	if (err)
	289	goto out_cleanup;
	290	}
	291
	292	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	293	if (err)
	294	goto out_cleanup;
	295
5955102c	296	inode_lock(newdentry->d_inode);
e9be9d5e	297	err = ovl_set_attr(newdentry, stat);
5955102c	298	inode_unlock(newdentry->d_inode);
e9be9d5e MS	299	if (err)
	300	goto out_cleanup;
	301
	302	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	303	if (err)
	304	goto out_cleanup;
	305
	306	ovl_dentry_update(dentry, newdentry);
39b681f8	307	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
e9be9d5e MS	308	newdentry = NULL;
	309
	310	/*
	311	* Non-directores become opaque when copied up.
	312	*/
	313	if (!S_ISDIR(stat->mode))
	314	ovl_dentry_set_opaque(dentry, true);
	315	out2:
	316	dput(upper);
	317	out1:
	318	dput(newdentry);
	319	out:
	320	return err;
	321
	322	out_cleanup:
	323	ovl_cleanup(wdir, newdentry);
ab79efab	324	goto out2;
e9be9d5e MS	325	}
	326
	327	/*
	328	* Copy up a single dentry
	329	*
	330	* Directory renames only allowed on "pure upper" (already created on
	331	* upper filesystem, never copied up). Directories which are on lower or
	332	* are merged may not be renamed. For these -EXDEV is returned and
	333	* userspace has to deal with it. This means, when copying up a
	334	* directory we can rely on it and ancestors being stable.
	335	*
	336	* Non-directory renames start with copy up of source if necessary. The
	337	* actual rename will only proceed once the copy up was successful. Copy
	338	* up uses upper parent i_mutex for exclusion. Since rename can change
	339	* d_parent it is possible that the copy up will lock the old parent. At
	340	* that point the file will have already been copied up anyway.
	341	*/
	342	int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
0f7ff2da	343	struct path lowerpath, struct kstat stat)
e9be9d5e MS	344	{
	345	struct dentry *workdir = ovl_workdir(dentry);
	346	int err;
	347	struct kstat pstat;
	348	struct path parentpath;
	349	struct dentry *upperdir;
	350	struct dentry *upperdentry;
	351	const struct cred *old_cred;
e9be9d5e MS	352	char *link = NULL;
e9be9d5e MS	353
cc6f67bc MS	354	if (WARN_ON(!workdir))
	355	return -EROFS;
	356
fb5bb2c3 DH	357	ovl_do_check_copy_up(lowerpath->dentry);
fb5bb2c3 DH	358
e9be9d5e MS	359	ovl_path_upper(parent, &parentpath);
	360	upperdir = parentpath.dentry;
	361
	362	err = vfs_getattr(&parentpath, &pstat);
	363	if (err)
	364	return err;
	365
	366	if (S_ISLNK(stat->mode)) {
	367	link = ovl_read_symlink(lowerpath->dentry);
	368	if (IS_ERR(link))
	369	return PTR_ERR(link);
	370	}
	371
3fe6e52f	372	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e MS	373
	374	err = -EIO;
	375	if (lock_rename(workdir, upperdir) != NULL) {
	376	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	377	goto out_unlock;
	378	}
	379	upperdentry = ovl_dentry_upper(dentry);
	380	if (upperdentry) {
0f7ff2da	381	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	382	err = 0;
0f7ff2da	383	goto out_unlock;
e9be9d5e MS	384	}
	385
	386	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
0f7ff2da	387	stat, link);
e9be9d5e MS	388	if (!err) {
	389	/* Restore timestamps on parent (best effort) */
	390	ovl_set_timestamps(upperdir, &pstat);
	391	}
	392	out_unlock:
	393	unlock_rename(workdir, upperdir);
e9be9d5e	394	revert_creds(old_cred);
e9be9d5e	395
e9be9d5e MS	396	if (link)
	397	free_page((unsigned long) link);
	398
	399	return err;
	400	}
	401
	402	int ovl_copy_up(struct dentry *dentry)
	403	{
	404	int err;
	405
	406	err = 0;
	407	while (!err) {
	408	struct dentry *next;
	409	struct dentry *parent;
	410	struct path lowerpath;
	411	struct kstat stat;
	412	enum ovl_path_type type = ovl_path_type(dentry);
	413
1afaba1e	414	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	415	break;
	416
	417	next = dget(dentry);
	418	/* find the topmost dentry not yet copied up */
	419	for (;;) {
	420	parent = dget_parent(next);
	421
	422	type = ovl_path_type(parent);
1afaba1e	423	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	424	break;
	425
	426	dput(next);
	427	next = parent;
	428	}
	429
	430	ovl_path_lower(next, &lowerpath);
	431	err = vfs_getattr(&lowerpath, &stat);
	432	if (!err)
0f7ff2da	433	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	434
	435	dput(parent);
	436	dput(next);
	437	}
	438
	439	return err;
	440	}