[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/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);

	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; name < (buf + list_size); name += strlen(name) + 1) {
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;
	const struct cred *old_creds = NULL;
	struct cred *new_creds = NULL;

	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;

	err = security_inode_copy_up(dentry, &new_creds);
	if (err < 0)
		goto out2;

	if (new_creds)
		old_creds = override_creds(new_creds);

	/* 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 (new_creds) {
		revert_creds(old_creds);
		put_cred(new_creds);
	}

	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);
e9be9d5e MS	60
	61	if (!old->d_inode->i_op->getxattr \|\|
	62	!new->d_inode->i_op->getxattr)
	63	return 0;
	64
	65	list_size = vfs_listxattr(old, NULL, 0);
	66	if (list_size <= 0) {
	67	if (list_size == -EOPNOTSUPP)
	68	return 0;
	69	return list_size;
	70	}
	71
	72	buf = kzalloc(list_size, GFP_KERNEL);
	73	if (!buf)
	74	return -ENOMEM;
	75
e9be9d5e MS	76	list_size = vfs_listxattr(old, buf, list_size);
	77	if (list_size <= 0) {
	78	error = list_size;
e4ad29fa	79	goto out;
e9be9d5e MS	80	}
	81
	82	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
e4ad29fa VC	83	retry:
	84	size = vfs_getxattr(old, name, value, value_size);
	85	if (size == -ERANGE)
	86	size = vfs_getxattr(old, name, NULL, 0);
	87
97daf8b9	88	if (size < 0) {
e9be9d5e	89	error = size;
e4ad29fa	90	break;
e9be9d5e	91	}
e4ad29fa VC	92
	93	if (size > value_size) {
	94	void *new;
	95
	96	new = krealloc(value, size, GFP_KERNEL);
	97	if (!new) {
	98	error = -ENOMEM;
	99	break;
	100	}
	101	value = new;
	102	value_size = size;
	103	goto retry;
	104	}
	105
e9be9d5e MS	106	error = vfs_setxattr(new, name, value, size, 0);
e9be9d5e MS	107	if (error)
e4ad29fa	108	break;
e9be9d5e	109	}
e9be9d5e MS	110	kfree(value);
	111	out:
	112	kfree(buf);
	113	return error;
	114	}
	115
	116	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
	117	{
	118	struct file *old_file;
	119	struct file *new_file;
	120	loff_t old_pos = 0;
	121	loff_t new_pos = 0;
	122	int error = 0;
	123
	124	if (len == 0)
	125	return 0;
	126
0480334f	127	old_file = ovl_path_open(old, O_LARGEFILE \| O_RDONLY);
e9be9d5e MS	128	if (IS_ERR(old_file))
	129	return PTR_ERR(old_file);
	130
0480334f	131	new_file = ovl_path_open(new, O_LARGEFILE \| O_WRONLY);
e9be9d5e MS	132	if (IS_ERR(new_file)) {
	133	error = PTR_ERR(new_file);
	134	goto out_fput;
	135	}
	136
	137	/* FIXME: copy up sparse files efficiently */
	138	while (len) {
	139	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
	140	long bytes;
	141
	142	if (len < this_len)
	143	this_len = len;
	144
	145	if (signal_pending_state(TASK_KILLABLE, current)) {
	146	error = -EINTR;
	147	break;
	148	}
	149
	150	bytes = do_splice_direct(old_file, &old_pos,
	151	new_file, &new_pos,
	152	this_len, SPLICE_F_MOVE);
	153	if (bytes <= 0) {
	154	error = bytes;
	155	break;
	156	}
	157	WARN_ON(old_pos != new_pos);
	158
	159	len -= bytes;
	160	}
	161
	162	fput(new_file);
	163	out_fput:
	164	fput(old_file);
	165	return error;
	166	}
	167
	168	static char ovl_read_symlink(struct dentry realdentry)
	169	{
	170	int res;
	171	char *buf;
	172	struct inode *inode = realdentry->d_inode;
	173	mm_segment_t old_fs;
	174
	175	res = -EINVAL;
	176	if (!inode->i_op->readlink)
	177	goto err;
	178
	179	res = -ENOMEM;
	180	buf = (char *) __get_free_page(GFP_KERNEL);
	181	if (!buf)
	182	goto err;
	183
	184	old_fs = get_fs();
	185	set_fs(get_ds());
	186	/* The cast to a user pointer is valid due to the set_fs() */
	187	res = inode->i_op->readlink(realdentry,
	188	(char __user *)buf, PAGE_SIZE - 1);
	189	set_fs(old_fs);
	190	if (res < 0) {
	191	free_page((unsigned long) buf);
	192	goto err;
	193	}
	194	buf[res] = '\0';
	195
196	return buf;
197
198	err:
199	return ERR_PTR(res);
200	}
201
202	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
203	{
204	struct iattr attr = {
205	.ia_valid =
206	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
207	.ia_atime = stat->atime,
208	.ia_mtime = stat->mtime,
209	};
210
211	return notify_change(upperdentry, &attr, NULL);
212	}
213
214	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
215	{
216	int err = 0;
217
218	if (!S_ISLNK(stat->mode)) {
219	struct iattr attr = {
220	.ia_valid = ATTR_MODE,
221	.ia_mode = stat->mode,
222	};
223	err = notify_change(upperdentry, &attr, NULL);
224	}
225	if (!err) {
226	struct iattr attr = {
227	.ia_valid = ATTR_UID \| ATTR_GID,
228	.ia_uid = stat->uid,
229	.ia_gid = stat->gid,
230	};
231	err = notify_change(upperdentry, &attr, NULL);
232	}
233	if (!err)
234	ovl_set_timestamps(upperdentry, stat);
235
236	return err;
e9be9d5e MS	237	}
	238
	239	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	240	struct dentry dentry, struct path lowerpath,
0f7ff2da	241	struct kstat stat, const char link)
e9be9d5e MS	242	{
	243	struct inode *wdir = workdir->d_inode;
	244	struct inode *udir = upperdir->d_inode;
	245	struct dentry *newdentry = NULL;
	246	struct dentry *upper = NULL;
	247	umode_t mode = stat->mode;
	248	int err;
d8ad8b49 VG	249	const struct cred *old_creds = NULL;
d8ad8b49 VG	250	struct cred *new_creds = NULL;
e9be9d5e MS	251
	252	newdentry = ovl_lookup_temp(workdir, dentry);
	253	err = PTR_ERR(newdentry);
	254	if (IS_ERR(newdentry))
	255	goto out;
	256
	257	upper = lookup_one_len(dentry->d_name.name, upperdir,
	258	dentry->d_name.len);
	259	err = PTR_ERR(upper);
	260	if (IS_ERR(upper))
	261	goto out1;
	262
d8ad8b49 VG	263	err = security_inode_copy_up(dentry, &new_creds);
	264	if (err < 0)
	265	goto out2;
	266
	267	if (new_creds)
	268	old_creds = override_creds(new_creds);
	269
e9be9d5e MS	270	/* Can't properly set mode on creation because of the umask */
	271	stat->mode &= S_IFMT;
	272	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	273	stat->mode = mode;
d8ad8b49 VG	274
	275	if (new_creds) {
	276	revert_creds(old_creds);
	277	put_cred(new_creds);
	278	}
	279
e9be9d5e MS	280	if (err)
	281	goto out2;
	282
	283	if (S_ISREG(stat->mode)) {
	284	struct path upperpath;
f134f244	285
e9be9d5e MS	286	ovl_path_upper(dentry, &upperpath);
	287	BUG_ON(upperpath.dentry != NULL);
	288	upperpath.dentry = newdentry;
	289
	290	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	291	if (err)
	292	goto out_cleanup;
	293	}
	294
	295	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	296	if (err)
	297	goto out_cleanup;
	298
5955102c	299	inode_lock(newdentry->d_inode);
e9be9d5e	300	err = ovl_set_attr(newdentry, stat);
5955102c	301	inode_unlock(newdentry->d_inode);
e9be9d5e MS	302	if (err)
	303	goto out_cleanup;
	304
	305	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	306	if (err)
	307	goto out_cleanup;
	308
	309	ovl_dentry_update(dentry, newdentry);
39b681f8	310	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
e9be9d5e MS	311	newdentry = NULL;
	312
	313	/*
	314	* Non-directores become opaque when copied up.
	315	*/
	316	if (!S_ISDIR(stat->mode))
	317	ovl_dentry_set_opaque(dentry, true);
	318	out2:
	319	dput(upper);
	320	out1:
	321	dput(newdentry);
	322	out:
	323	return err;
	324
	325	out_cleanup:
	326	ovl_cleanup(wdir, newdentry);
ab79efab	327	goto out2;
e9be9d5e MS	328	}
	329
	330	/*
	331	* Copy up a single dentry
	332	*
	333	* Directory renames only allowed on "pure upper" (already created on
	334	* upper filesystem, never copied up). Directories which are on lower or
	335	* are merged may not be renamed. For these -EXDEV is returned and
	336	* userspace has to deal with it. This means, when copying up a
	337	* directory we can rely on it and ancestors being stable.
	338	*
	339	* Non-directory renames start with copy up of source if necessary. The
	340	* actual rename will only proceed once the copy up was successful. Copy
	341	* up uses upper parent i_mutex for exclusion. Since rename can change
	342	* d_parent it is possible that the copy up will lock the old parent. At
	343	* that point the file will have already been copied up anyway.
	344	*/
	345	int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
0f7ff2da	346	struct path lowerpath, struct kstat stat)
e9be9d5e MS	347	{
	348	struct dentry *workdir = ovl_workdir(dentry);
	349	int err;
	350	struct kstat pstat;
	351	struct path parentpath;
	352	struct dentry *upperdir;
	353	struct dentry *upperdentry;
	354	const struct cred *old_cred;
e9be9d5e MS	355	char *link = NULL;
e9be9d5e MS	356
cc6f67bc MS	357	if (WARN_ON(!workdir))
	358	return -EROFS;
	359
fb5bb2c3 DH	360	ovl_do_check_copy_up(lowerpath->dentry);
fb5bb2c3 DH	361
e9be9d5e MS	362	ovl_path_upper(parent, &parentpath);
	363	upperdir = parentpath.dentry;
	364
	365	err = vfs_getattr(&parentpath, &pstat);
	366	if (err)
	367	return err;
	368
	369	if (S_ISLNK(stat->mode)) {
	370	link = ovl_read_symlink(lowerpath->dentry);
	371	if (IS_ERR(link))
	372	return PTR_ERR(link);
	373	}
	374
3fe6e52f	375	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e MS	376
	377	err = -EIO;
	378	if (lock_rename(workdir, upperdir) != NULL) {
	379	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	380	goto out_unlock;
	381	}
	382	upperdentry = ovl_dentry_upper(dentry);
	383	if (upperdentry) {
0f7ff2da	384	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	385	err = 0;
0f7ff2da	386	goto out_unlock;
e9be9d5e MS	387	}
	388
	389	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
0f7ff2da	390	stat, link);
e9be9d5e MS	391	if (!err) {
	392	/* Restore timestamps on parent (best effort) */
	393	ovl_set_timestamps(upperdir, &pstat);
	394	}
	395	out_unlock:
	396	unlock_rename(workdir, upperdir);
e9be9d5e	397	revert_creds(old_cred);
e9be9d5e	398
e9be9d5e MS	399	if (link)
	400	free_page((unsigned long) link);
	401
	402	return err;
	403	}
	404
	405	int ovl_copy_up(struct dentry *dentry)
	406	{
	407	int err;
	408
	409	err = 0;
	410	while (!err) {
	411	struct dentry *next;
	412	struct dentry *parent;
	413	struct path lowerpath;
	414	struct kstat stat;
	415	enum ovl_path_type type = ovl_path_type(dentry);
	416
1afaba1e	417	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	418	break;
	419
	420	next = dget(dentry);
	421	/* find the topmost dentry not yet copied up */
	422	for (;;) {
	423	parent = dget_parent(next);
	424
	425	type = ovl_path_type(parent);
1afaba1e	426	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	427	break;
	428
	429	dput(next);
	430	next = parent;
	431	}
	432
	433	ovl_path_lower(next, &lowerpath);
	434	err = vfs_getattr(&lowerpath, &stat);
	435	if (!err)
0f7ff2da	436	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	437
	438	dput(parent);
	439	dput(next);
	440	}
	441
	442	return err;
	443	}