[deliverable/linux.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 = security_inode_copy_up_xattr(name);
		if (error < 0 && error != -EOPNOTSUPP)
			break;
		if (error == 1) {
			error = 0;
			continue; /* Discard */
		}
		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
121ab822 VG	106	error = security_inode_copy_up_xattr(name);
	107	if (error < 0 && error != -EOPNOTSUPP)
	108	break;
	109	if (error == 1) {
	110	error = 0;
	111	continue; /* Discard */
	112	}
e9be9d5e MS	113	error = vfs_setxattr(new, name, value, size, 0);
e9be9d5e MS	114	if (error)
e4ad29fa	115	break;
e9be9d5e	116	}
e9be9d5e MS	117	kfree(value);
	118	out:
	119	kfree(buf);
	120	return error;
	121	}
	122
	123	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
	124	{
	125	struct file *old_file;
	126	struct file *new_file;
	127	loff_t old_pos = 0;
	128	loff_t new_pos = 0;
	129	int error = 0;
	130
	131	if (len == 0)
	132	return 0;
	133
0480334f	134	old_file = ovl_path_open(old, O_LARGEFILE \| O_RDONLY);
e9be9d5e MS	135	if (IS_ERR(old_file))
	136	return PTR_ERR(old_file);
	137
0480334f	138	new_file = ovl_path_open(new, O_LARGEFILE \| O_WRONLY);
e9be9d5e MS	139	if (IS_ERR(new_file)) {
	140	error = PTR_ERR(new_file);
	141	goto out_fput;
	142	}
	143
	144	/* FIXME: copy up sparse files efficiently */
	145	while (len) {
	146	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
	147	long bytes;
	148
	149	if (len < this_len)
	150	this_len = len;
	151
	152	if (signal_pending_state(TASK_KILLABLE, current)) {
	153	error = -EINTR;
	154	break;
	155	}
	156
	157	bytes = do_splice_direct(old_file, &old_pos,
	158	new_file, &new_pos,
	159	this_len, SPLICE_F_MOVE);
	160	if (bytes <= 0) {
	161	error = bytes;
	162	break;
	163	}
	164	WARN_ON(old_pos != new_pos);
	165
	166	len -= bytes;
	167	}
	168
	169	fput(new_file);
	170	out_fput:
	171	fput(old_file);
	172	return error;
	173	}
	174
	175	static char ovl_read_symlink(struct dentry realdentry)
	176	{
	177	int res;
	178	char *buf;
	179	struct inode *inode = realdentry->d_inode;
	180	mm_segment_t old_fs;
	181
	182	res = -EINVAL;
	183	if (!inode->i_op->readlink)
	184	goto err;
	185
	186	res = -ENOMEM;
	187	buf = (char *) __get_free_page(GFP_KERNEL);
	188	if (!buf)
	189	goto err;
	190
	191	old_fs = get_fs();
	192	set_fs(get_ds());
	193	/* The cast to a user pointer is valid due to the set_fs() */
	194	res = inode->i_op->readlink(realdentry,
	195	(char __user *)buf, PAGE_SIZE - 1);
	196	set_fs(old_fs);
	197	if (res < 0) {
	198	free_page((unsigned long) buf);
	199	goto err;
	200	}
	201	buf[res] = '\0';
	202
203	return buf;
204
205	err:
206	return ERR_PTR(res);
207	}
208
209	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
210	{
211	struct iattr attr = {
212	.ia_valid =
213	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
214	.ia_atime = stat->atime,
215	.ia_mtime = stat->mtime,
216	};
217
218	return notify_change(upperdentry, &attr, NULL);
219	}
220
221	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
222	{
223	int err = 0;
224
225	if (!S_ISLNK(stat->mode)) {
226	struct iattr attr = {
227	.ia_valid = ATTR_MODE,
228	.ia_mode = stat->mode,
229	};
230	err = notify_change(upperdentry, &attr, NULL);
231	}
232	if (!err) {
233	struct iattr attr = {
234	.ia_valid = ATTR_UID \| ATTR_GID,
235	.ia_uid = stat->uid,
236	.ia_gid = stat->gid,
237	};
238	err = notify_change(upperdentry, &attr, NULL);
239	}
240	if (!err)
241	ovl_set_timestamps(upperdentry, stat);
242
243	return err;
e9be9d5e MS	244	}
	245
	246	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	247	struct dentry dentry, struct path lowerpath,
0f7ff2da	248	struct kstat stat, const char link)
e9be9d5e MS	249	{
	250	struct inode *wdir = workdir->d_inode;
	251	struct inode *udir = upperdir->d_inode;
	252	struct dentry *newdentry = NULL;
	253	struct dentry *upper = NULL;
	254	umode_t mode = stat->mode;
	255	int err;
d8ad8b49 VG	256	const struct cred *old_creds = NULL;
d8ad8b49 VG	257	struct cred *new_creds = NULL;
e9be9d5e MS	258
	259	newdentry = ovl_lookup_temp(workdir, dentry);
	260	err = PTR_ERR(newdentry);
	261	if (IS_ERR(newdentry))
	262	goto out;
	263
	264	upper = lookup_one_len(dentry->d_name.name, upperdir,
	265	dentry->d_name.len);
	266	err = PTR_ERR(upper);
	267	if (IS_ERR(upper))
	268	goto out1;
	269
d8ad8b49 VG	270	err = security_inode_copy_up(dentry, &new_creds);
	271	if (err < 0)
	272	goto out2;
	273
	274	if (new_creds)
	275	old_creds = override_creds(new_creds);
	276
e9be9d5e MS	277	/* Can't properly set mode on creation because of the umask */
	278	stat->mode &= S_IFMT;
	279	err = ovl_create_real(wdir, newdentry, stat, link, NULL, true);
	280	stat->mode = mode;
d8ad8b49 VG	281
	282	if (new_creds) {
	283	revert_creds(old_creds);
	284	put_cred(new_creds);
	285	}
	286
e9be9d5e MS	287	if (err)
	288	goto out2;
	289
	290	if (S_ISREG(stat->mode)) {
	291	struct path upperpath;
f134f244	292
e9be9d5e MS	293	ovl_path_upper(dentry, &upperpath);
	294	BUG_ON(upperpath.dentry != NULL);
	295	upperpath.dentry = newdentry;
	296
	297	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	298	if (err)
	299	goto out_cleanup;
	300	}
	301
	302	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	303	if (err)
	304	goto out_cleanup;
	305
5955102c	306	inode_lock(newdentry->d_inode);
e9be9d5e	307	err = ovl_set_attr(newdentry, stat);
5955102c	308	inode_unlock(newdentry->d_inode);
e9be9d5e MS	309	if (err)
	310	goto out_cleanup;
	311
	312	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	313	if (err)
	314	goto out_cleanup;
	315
	316	ovl_dentry_update(dentry, newdentry);
39b681f8	317	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
e9be9d5e MS	318	newdentry = NULL;
	319
	320	/*
	321	* Non-directores become opaque when copied up.
	322	*/
	323	if (!S_ISDIR(stat->mode))
	324	ovl_dentry_set_opaque(dentry, true);
	325	out2:
	326	dput(upper);
	327	out1:
	328	dput(newdentry);
	329	out:
	330	return err;
	331
	332	out_cleanup:
	333	ovl_cleanup(wdir, newdentry);
ab79efab	334	goto out2;
e9be9d5e MS	335	}
	336
	337	/*
	338	* Copy up a single dentry
	339	*
	340	* Directory renames only allowed on "pure upper" (already created on
	341	* upper filesystem, never copied up). Directories which are on lower or
	342	* are merged may not be renamed. For these -EXDEV is returned and
	343	* userspace has to deal with it. This means, when copying up a
	344	* directory we can rely on it and ancestors being stable.
	345	*
	346	* Non-directory renames start with copy up of source if necessary. The
	347	* actual rename will only proceed once the copy up was successful. Copy
	348	* up uses upper parent i_mutex for exclusion. Since rename can change
	349	* d_parent it is possible that the copy up will lock the old parent. At
	350	* that point the file will have already been copied up anyway.
	351	*/
	352	int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
0f7ff2da	353	struct path lowerpath, struct kstat stat)
e9be9d5e MS	354	{
	355	struct dentry *workdir = ovl_workdir(dentry);
	356	int err;
	357	struct kstat pstat;
	358	struct path parentpath;
	359	struct dentry *upperdir;
	360	struct dentry *upperdentry;
	361	const struct cred *old_cred;
e9be9d5e MS	362	char *link = NULL;
e9be9d5e MS	363
cc6f67bc MS	364	if (WARN_ON(!workdir))
	365	return -EROFS;
	366
fb5bb2c3 DH	367	ovl_do_check_copy_up(lowerpath->dentry);
fb5bb2c3 DH	368
e9be9d5e MS	369	ovl_path_upper(parent, &parentpath);
	370	upperdir = parentpath.dentry;
	371
	372	err = vfs_getattr(&parentpath, &pstat);
	373	if (err)
	374	return err;
	375
	376	if (S_ISLNK(stat->mode)) {
	377	link = ovl_read_symlink(lowerpath->dentry);
	378	if (IS_ERR(link))
	379	return PTR_ERR(link);
	380	}
	381
3fe6e52f	382	old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e MS	383
	384	err = -EIO;
	385	if (lock_rename(workdir, upperdir) != NULL) {
	386	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	387	goto out_unlock;
	388	}
	389	upperdentry = ovl_dentry_upper(dentry);
	390	if (upperdentry) {
0f7ff2da	391	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	392	err = 0;
0f7ff2da	393	goto out_unlock;
e9be9d5e MS	394	}
	395
	396	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
0f7ff2da	397	stat, link);
e9be9d5e MS	398	if (!err) {
	399	/* Restore timestamps on parent (best effort) */
	400	ovl_set_timestamps(upperdir, &pstat);
	401	}
	402	out_unlock:
	403	unlock_rename(workdir, upperdir);
e9be9d5e	404	revert_creds(old_cred);
e9be9d5e	405
e9be9d5e MS	406	if (link)
	407	free_page((unsigned long) link);
	408
	409	return err;
	410	}
	411
	412	int ovl_copy_up(struct dentry *dentry)
	413	{
	414	int err;
	415
	416	err = 0;
	417	while (!err) {
	418	struct dentry *next;
	419	struct dentry *parent;
	420	struct path lowerpath;
	421	struct kstat stat;
	422	enum ovl_path_type type = ovl_path_type(dentry);
	423
1afaba1e	424	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	425	break;
	426
	427	next = dget(dentry);
	428	/* find the topmost dentry not yet copied up */
	429	for (;;) {
	430	parent = dget_parent(next);
	431
	432	type = ovl_path_type(parent);
1afaba1e	433	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	434	break;
	435
	436	dput(next);
	437	next = parent;
	438	}
	439
	440	ovl_path_lower(next, &lowerpath);
	441	err = vfs_getattr(&lowerpath, &stat);
	442	if (!err)
0f7ff2da	443	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	444
	445	dput(parent);
	446	dput(next);
	447	}
	448
	449	return err;
	450	}