[mirror_ubuntu-bionic-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 (file_inode(f) == 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_opflags & IOP_XATTR) ||
	    !(new->d_inode->i_opflags & IOP_XATTR))
		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 = 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;
	}

	/* Try to use clone_file_range to clone up within the same fs */
	error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
	if (!error)
		goto out;
	/* Couldn't clone, so now we try to copy the data */
	error = 0;

	/* 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;
	}
out:
	if (!error)
		error = vfs_fsync(new_file, 0);
	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;
	int err;
	const struct cred *old_creds = NULL;
	struct cred *new_creds = NULL;
	struct cattr cattr = {
		/* Can't properly set mode on creation because of the umask */
		.mode = stat->mode & S_IFMT,
		.rdev = stat->rdev,
		.link = link
	};

	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);

	err = ovl_create_real(wdir, newdentry, &cattr, NULL, true);

	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;
out2:
	dput(upper);
out1:
	dput(newdentry);
out:
	return err;

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

/*
 * Copy up a single dentry
 *
 * All 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.
 */
static 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;
	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;
	}
	if (ovl_dentry_upper(dentry)) {
		/* 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_flags(struct dentry *dentry, int flags)
{
	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);
		/* maybe truncate regular file. this has no effect on dirs */
		if (flags & O_TRUNC)
			stat.size = 0;
		if (!err)
			err = ovl_copy_up_one(parent, next, &lowerpath, &stat);

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

	return err;
}

int ovl_copy_up(struct dentry *dentry)
{
	return ovl_copy_up_flags(dentry, 0);
}
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
45063097	36	if (file_inode(f) == d_inode(dentry))
fb5bb2c3 DH	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	61
5d6c3191 AG	62	if (!(old->d_inode->i_opflags & IOP_XATTR) \|\|
5d6c3191 AG	63	!(new->d_inode->i_opflags & IOP_XATTR))
e9be9d5e MS	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
121ab822 VG	118	error = security_inode_copy_up_xattr(name);
	119	if (error < 0 && error != -EOPNOTSUPP)
	120	break;
	121	if (error == 1) {
	122	error = 0;
	123	continue; /* Discard */
	124	}
e9be9d5e MS	125	error = vfs_setxattr(new, name, value, size, 0);
e9be9d5e MS	126	if (error)
e4ad29fa	127	break;
e9be9d5e	128	}
e9be9d5e MS	129	kfree(value);
	130	out:
	131	kfree(buf);
	132	return error;
	133	}
	134
	135	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
	136	{
	137	struct file *old_file;
	138	struct file *new_file;
	139	loff_t old_pos = 0;
	140	loff_t new_pos = 0;
	141	int error = 0;
	142
	143	if (len == 0)
	144	return 0;
	145
0480334f	146	old_file = ovl_path_open(old, O_LARGEFILE \| O_RDONLY);
e9be9d5e MS	147	if (IS_ERR(old_file))
	148	return PTR_ERR(old_file);
	149
0480334f	150	new_file = ovl_path_open(new, O_LARGEFILE \| O_WRONLY);
e9be9d5e MS	151	if (IS_ERR(new_file)) {
	152	error = PTR_ERR(new_file);
	153	goto out_fput;
	154	}
	155
2ea98466 AG	156	/* Try to use clone_file_range to clone up within the same fs */
	157	error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
	158	if (!error)
	159	goto out;
	160	/* Couldn't clone, so now we try to copy the data */
	161	error = 0;
	162
e9be9d5e MS	163	/* FIXME: copy up sparse files efficiently */
	164	while (len) {
	165	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
	166	long bytes;
	167
	168	if (len < this_len)
	169	this_len = len;
	170
	171	if (signal_pending_state(TASK_KILLABLE, current)) {
	172	error = -EINTR;
	173	break;
	174	}
	175
	176	bytes = do_splice_direct(old_file, &old_pos,
	177	new_file, &new_pos,
	178	this_len, SPLICE_F_MOVE);
	179	if (bytes <= 0) {
	180	error = bytes;
	181	break;
	182	}
	183	WARN_ON(old_pos != new_pos);
	184
	185	len -= bytes;
	186	}
2ea98466	187	out:
641089c1 MS	188	if (!error)
641089c1 MS	189	error = vfs_fsync(new_file, 0);
e9be9d5e MS	190	fput(new_file);
	191	out_fput:
	192	fput(old_file);
	193	return error;
	194	}
	195
e9be9d5e MS	196	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
	197	{
	198	struct iattr attr = {
	199	.ia_valid =
	200	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
	201	.ia_atime = stat->atime,
	202	.ia_mtime = stat->mtime,
	203	};
	204
	205	return notify_change(upperdentry, &attr, NULL);
	206	}
	207
	208	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
	209	{
	210	int err = 0;
	211
	212	if (!S_ISLNK(stat->mode)) {
	213	struct iattr attr = {
	214	.ia_valid = ATTR_MODE,
	215	.ia_mode = stat->mode,
	216	};
	217	err = notify_change(upperdentry, &attr, NULL);
	218	}
	219	if (!err) {
	220	struct iattr attr = {
	221	.ia_valid = ATTR_UID \| ATTR_GID,
	222	.ia_uid = stat->uid,
	223	.ia_gid = stat->gid,
	224	};
	225	err = notify_change(upperdentry, &attr, NULL);
	226	}
	227	if (!err)
	228	ovl_set_timestamps(upperdentry, stat);
	229
	230	return err;
e9be9d5e MS	231	}
	232
	233	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	234	struct dentry dentry, struct path lowerpath,
0f7ff2da	235	struct kstat stat, const char link)
e9be9d5e MS	236	{
	237	struct inode *wdir = workdir->d_inode;
	238	struct inode *udir = upperdir->d_inode;
	239	struct dentry *newdentry = NULL;
	240	struct dentry *upper = NULL;
e9be9d5e	241	int err;
d8ad8b49 VG	242	const struct cred *old_creds = NULL;
d8ad8b49 VG	243	struct cred *new_creds = NULL;
32a3d848 AV	244	struct cattr cattr = {
	245	/* Can't properly set mode on creation because of the umask */
	246	.mode = stat->mode & S_IFMT,
	247	.rdev = stat->rdev,
	248	.link = link
	249	};
e9be9d5e MS	250
	251	newdentry = ovl_lookup_temp(workdir, dentry);
	252	err = PTR_ERR(newdentry);
	253	if (IS_ERR(newdentry))
	254	goto out;
	255
	256	upper = lookup_one_len(dentry->d_name.name, upperdir,
	257	dentry->d_name.len);
	258	err = PTR_ERR(upper);
	259	if (IS_ERR(upper))
	260	goto out1;
	261
d8ad8b49 VG	262	err = security_inode_copy_up(dentry, &new_creds);
	263	if (err < 0)
	264	goto out2;
	265
	266	if (new_creds)
	267	old_creds = override_creds(new_creds);
	268
32a3d848	269	err = ovl_create_real(wdir, newdentry, &cattr, NULL, true);
d8ad8b49 VG	270
	271	if (new_creds) {
	272	revert_creds(old_creds);
	273	put_cred(new_creds);
	274	}
	275
e9be9d5e MS	276	if (err)
	277	goto out2;
	278
	279	if (S_ISREG(stat->mode)) {
	280	struct path upperpath;
f134f244	281
e9be9d5e MS	282	ovl_path_upper(dentry, &upperpath);
	283	BUG_ON(upperpath.dentry != NULL);
	284	upperpath.dentry = newdentry;
	285
	286	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	287	if (err)
	288	goto out_cleanup;
	289	}
	290
	291	err = ovl_copy_xattr(lowerpath->dentry, newdentry);
	292	if (err)
	293	goto out_cleanup;
	294
5955102c	295	inode_lock(newdentry->d_inode);
e9be9d5e	296	err = ovl_set_attr(newdentry, stat);
5955102c	297	inode_unlock(newdentry->d_inode);
e9be9d5e MS	298	if (err)
	299	goto out_cleanup;
	300
	301	err = ovl_do_rename(wdir, newdentry, udir, upper, 0);
	302	if (err)
	303	goto out_cleanup;
	304
	305	ovl_dentry_update(dentry, newdentry);
39b681f8	306	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
e9be9d5e	307	newdentry = NULL;
e9be9d5e MS	308	out2:
	309	dput(upper);
	310	out1:
	311	dput(newdentry);
	312	out:
	313	return err;
	314
	315	out_cleanup:
	316	ovl_cleanup(wdir, newdentry);
ab79efab	317	goto out2;
e9be9d5e MS	318	}
	319
	320	/*
	321	* Copy up a single dentry
	322	*
a6c60655 MS	323	* All renames start with copy up of source if necessary. The actual
	324	* rename will only proceed once the copy up was successful. Copy up uses
	325	* upper parent i_mutex for exclusion. Since rename can change d_parent it
	326	* is possible that the copy up will lock the old parent. At that point
	327	* the file will have already been copied up anyway.
e9be9d5e	328	*/
9aba6521 AG	329	static int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
9aba6521 AG	330	struct path lowerpath, struct kstat stat)
e9be9d5e	331	{
7764235b	332	DEFINE_DELAYED_CALL(done);
e9be9d5e MS	333	struct dentry *workdir = ovl_workdir(dentry);
	334	int err;
	335	struct kstat pstat;
	336	struct path parentpath;
7764235b	337	struct dentry *lowerdentry = lowerpath->dentry;
e9be9d5e	338	struct dentry *upperdir;
7764235b	339	const char *link = NULL;
e9be9d5e	340
cc6f67bc MS	341	if (WARN_ON(!workdir))
	342	return -EROFS;
	343
7764235b	344	ovl_do_check_copy_up(lowerdentry);
fb5bb2c3	345
e9be9d5e MS	346	ovl_path_upper(parent, &parentpath);
	347	upperdir = parentpath.dentry;
	348
	349	err = vfs_getattr(&parentpath, &pstat);
	350	if (err)
	351	return err;
	352
	353	if (S_ISLNK(stat->mode)) {
7764235b	354	link = vfs_get_link(lowerdentry, &done);
e9be9d5e MS	355	if (IS_ERR(link))
	356	return PTR_ERR(link);
	357	}
	358
e9be9d5e MS	359	err = -EIO;
	360	if (lock_rename(workdir, upperdir) != NULL) {
	361	pr_err("overlayfs: failed to lock workdir+upperdir\n");
	362	goto out_unlock;
	363	}
a6c60655	364	if (ovl_dentry_upper(dentry)) {
0f7ff2da	365	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	366	err = 0;
0f7ff2da	367	goto out_unlock;
e9be9d5e MS	368	}
	369
	370	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
0f7ff2da	371	stat, link);
e9be9d5e MS	372	if (!err) {
	373	/* Restore timestamps on parent (best effort) */
	374	ovl_set_timestamps(upperdir, &pstat);
	375	}
	376	out_unlock:
	377	unlock_rename(workdir, upperdir);
7764235b	378	do_delayed_call(&done);
e9be9d5e MS	379
	380	return err;
	381	}
	382
9aba6521	383	int ovl_copy_up_flags(struct dentry *dentry, int flags)
e9be9d5e	384	{
8eac98b8 VG	385	int err = 0;
8eac98b8 VG	386	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	387
e9be9d5e MS	388	while (!err) {
	389	struct dentry *next;
	390	struct dentry *parent;
	391	struct path lowerpath;
	392	struct kstat stat;
	393	enum ovl_path_type type = ovl_path_type(dentry);
	394
1afaba1e	395	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	396	break;
	397
	398	next = dget(dentry);
	399	/* find the topmost dentry not yet copied up */
	400	for (;;) {
	401	parent = dget_parent(next);
	402
	403	type = ovl_path_type(parent);
1afaba1e	404	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	405	break;
	406
	407	dput(next);
	408	next = parent;
	409	}
	410
	411	ovl_path_lower(next, &lowerpath);
	412	err = vfs_getattr(&lowerpath, &stat);
9aba6521 AG	413	/* maybe truncate regular file. this has no effect on dirs */
	414	if (flags & O_TRUNC)
	415	stat.size = 0;
e9be9d5e	416	if (!err)
0f7ff2da	417	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	418
	419	dput(parent);
	420	dput(next);
	421	}
8eac98b8	422	revert_creds(old_cred);
e9be9d5e MS	423
	424	return err;
	425	}
9aba6521 AG	426
	427	int ovl_copy_up(struct dentry *dentry)
	428	{
	429	return ovl_copy_up_flags(dentry, 0);
	430	}