[linux-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"
#include "ovl_entry.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 kstat *pstat, bool tmpfile)
{
	struct inode *wdir = workdir->d_inode;
	struct inode *udir = upperdir->d_inode;
	struct dentry *newdentry = NULL;
	struct dentry *upper = NULL;
	struct dentry *temp = 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
	};

	upper = lookup_one_len(dentry->d_name.name, upperdir,
			       dentry->d_name.len);
	err = PTR_ERR(upper);
	if (IS_ERR(upper))
		goto out;

	err = security_inode_copy_up(dentry, &new_creds);
	if (err < 0)
		goto out1;

	if (new_creds)
		old_creds = override_creds(new_creds);

	if (tmpfile)
		temp = ovl_do_tmpfile(upperdir, stat->mode);
	else
		temp = ovl_lookup_temp(workdir, dentry);
	err = PTR_ERR(temp);
	if (IS_ERR(temp))
		goto out1;

	err = 0;
	if (!tmpfile)
		err = ovl_create_real(wdir, temp, &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 = temp;

		err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
		if (err)
			goto out_cleanup;
	}

	err = ovl_copy_xattr(lowerpath->dentry, temp);
	if (err)
		goto out_cleanup;

	inode_lock(temp->d_inode);
	err = ovl_set_attr(temp, stat);
	inode_unlock(temp->d_inode);
	if (err)
		goto out_cleanup;

	if (tmpfile)
		err = ovl_do_link(temp, udir, upper, true);
	else
		err = ovl_do_rename(wdir, temp, udir, upper, 0);
	if (err)
		goto out_cleanup;

	newdentry = dget(tmpfile ? upper : temp);
	ovl_dentry_update(dentry, newdentry);
	ovl_inode_update(d_inode(dentry), d_inode(newdentry));

	/* Restore timestamps on parent (best effort) */
	ovl_set_timestamps(upperdir, pstat);
out2:
	dput(temp);
out1:
	dput(upper);
out:
	return err;

out_cleanup:
	if (!tmpfile)
		ovl_cleanup(wdir, temp);
	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;
	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
	/* Should we copyup with O_TMPFILE or with workdir? */
	bool tmpfile = S_ISREG(stat->mode) && ofs->tmpfile;

	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, &pstat, tmpfile);
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	22	#include "overlayfs.h"
d8514d8e	23	#include "ovl_entry.h"
e9be9d5e MS	24
	25	#define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
	26
fb5bb2c3 DH	27	static bool __read_mostly ovl_check_copy_up;
	28	module_param_named(check_copy_up, ovl_check_copy_up, bool,
	29	S_IWUSR \| S_IRUGO);
	30	MODULE_PARM_DESC(ovl_check_copy_up,
	31	"Warn on copy-up when causing process also has a R/O fd open");
	32
	33	static int ovl_check_fd(const void data, struct file f, unsigned int fd)
	34	{
	35	const struct dentry *dentry = data;
	36
45063097	37	if (file_inode(f) == d_inode(dentry))
fb5bb2c3 DH	38	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",
	39	f, fd, current->pid, current->comm);
	40	return 0;
	41	}
	42
	43	/*
	44	* Check the fds open by this process and warn if something like the following
	45	* scenario is about to occur:
	46	*
	47	* fd1 = open("foo", O_RDONLY);
	48	* fd2 = open("foo", O_RDWR);
	49	*/
	50	static void ovl_do_check_copy_up(struct dentry *dentry)
	51	{
	52	if (ovl_check_copy_up)
	53	iterate_fd(current->files, 0, ovl_check_fd, dentry);
	54	}
	55
e9be9d5e MS	56	int ovl_copy_xattr(struct dentry old, struct dentry new)
e9be9d5e MS	57	{
e4ad29fa VC	58	ssize_t list_size, size, value_size = 0;
	59	char buf, name, *value = NULL;
	60	int uninitialized_var(error);
8b326c61	61	size_t slen;
e9be9d5e	62
5d6c3191 AG	63	if (!(old->d_inode->i_opflags & IOP_XATTR) \|\|
5d6c3191 AG	64	!(new->d_inode->i_opflags & IOP_XATTR))
e9be9d5e MS	65	return 0;
	66
	67	list_size = vfs_listxattr(old, NULL, 0);
	68	if (list_size <= 0) {
	69	if (list_size == -EOPNOTSUPP)
	70	return 0;
	71	return list_size;
	72	}
	73
	74	buf = kzalloc(list_size, GFP_KERNEL);
	75	if (!buf)
	76	return -ENOMEM;
	77
e9be9d5e MS	78	list_size = vfs_listxattr(old, buf, list_size);
	79	if (list_size <= 0) {
	80	error = list_size;
e4ad29fa	81	goto out;
e9be9d5e MS	82	}
e9be9d5e MS	83
8b326c61 MS	84	for (name = buf; list_size; name += slen) {
	85	slen = strnlen(name, list_size) + 1;
	86
	87	/* underlying fs providing us with an broken xattr list? */
	88	if (WARN_ON(slen > list_size)) {
	89	error = -EIO;
	90	break;
	91	}
	92	list_size -= slen;
	93
0956254a MS	94	if (ovl_is_private_xattr(name))
0956254a MS	95	continue;
e4ad29fa VC	96	retry:
	97	size = vfs_getxattr(old, name, value, value_size);
	98	if (size == -ERANGE)
	99	size = vfs_getxattr(old, name, NULL, 0);
	100
97daf8b9	101	if (size < 0) {
e9be9d5e	102	error = size;
e4ad29fa	103	break;
e9be9d5e	104	}
e4ad29fa VC	105
	106	if (size > value_size) {
	107	void *new;
	108
	109	new = krealloc(value, size, GFP_KERNEL);
	110	if (!new) {
	111	error = -ENOMEM;
	112	break;
	113	}
	114	value = new;
	115	value_size = size;
	116	goto retry;
	117	}
	118
121ab822 VG	119	error = security_inode_copy_up_xattr(name);
	120	if (error < 0 && error != -EOPNOTSUPP)
	121	break;
	122	if (error == 1) {
	123	error = 0;
	124	continue; /* Discard */
	125	}
e9be9d5e MS	126	error = vfs_setxattr(new, name, value, size, 0);
e9be9d5e MS	127	if (error)
e4ad29fa	128	break;
e9be9d5e	129	}
e9be9d5e MS	130	kfree(value);
	131	out:
	132	kfree(buf);
	133	return error;
	134	}
	135
	136	static int ovl_copy_up_data(struct path old, struct path new, loff_t len)
	137	{
	138	struct file *old_file;
	139	struct file *new_file;
	140	loff_t old_pos = 0;
	141	loff_t new_pos = 0;
	142	int error = 0;
	143
	144	if (len == 0)
	145	return 0;
	146
0480334f	147	old_file = ovl_path_open(old, O_LARGEFILE \| O_RDONLY);
e9be9d5e MS	148	if (IS_ERR(old_file))
	149	return PTR_ERR(old_file);
	150
0480334f	151	new_file = ovl_path_open(new, O_LARGEFILE \| O_WRONLY);
e9be9d5e MS	152	if (IS_ERR(new_file)) {
	153	error = PTR_ERR(new_file);
	154	goto out_fput;
	155	}
	156
2ea98466 AG	157	/* Try to use clone_file_range to clone up within the same fs */
	158	error = vfs_clone_file_range(old_file, 0, new_file, 0, len);
	159	if (!error)
	160	goto out;
	161	/* Couldn't clone, so now we try to copy the data */
	162	error = 0;
	163
e9be9d5e MS	164	/* FIXME: copy up sparse files efficiently */
	165	while (len) {
	166	size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
	167	long bytes;
	168
	169	if (len < this_len)
	170	this_len = len;
	171
	172	if (signal_pending_state(TASK_KILLABLE, current)) {
	173	error = -EINTR;
	174	break;
	175	}
	176
	177	bytes = do_splice_direct(old_file, &old_pos,
	178	new_file, &new_pos,
	179	this_len, SPLICE_F_MOVE);
	180	if (bytes <= 0) {
	181	error = bytes;
	182	break;
	183	}
	184	WARN_ON(old_pos != new_pos);
	185
	186	len -= bytes;
	187	}
2ea98466	188	out:
641089c1 MS	189	if (!error)
641089c1 MS	190	error = vfs_fsync(new_file, 0);
e9be9d5e MS	191	fput(new_file);
	192	out_fput:
	193	fput(old_file);
	194	return error;
	195	}
	196
e9be9d5e MS	197	static int ovl_set_timestamps(struct dentry upperdentry, struct kstat stat)
	198	{
	199	struct iattr attr = {
	200	.ia_valid =
	201	ATTR_ATIME \| ATTR_MTIME \| ATTR_ATIME_SET \| ATTR_MTIME_SET,
	202	.ia_atime = stat->atime,
	203	.ia_mtime = stat->mtime,
	204	};
	205
	206	return notify_change(upperdentry, &attr, NULL);
	207	}
	208
	209	int ovl_set_attr(struct dentry upperdentry, struct kstat stat)
	210	{
	211	int err = 0;
	212
	213	if (!S_ISLNK(stat->mode)) {
	214	struct iattr attr = {
	215	.ia_valid = ATTR_MODE,
	216	.ia_mode = stat->mode,
	217	};
	218	err = notify_change(upperdentry, &attr, NULL);
	219	}
	220	if (!err) {
	221	struct iattr attr = {
	222	.ia_valid = ATTR_UID \| ATTR_GID,
	223	.ia_uid = stat->uid,
	224	.ia_gid = stat->gid,
	225	};
	226	err = notify_change(upperdentry, &attr, NULL);
	227	}
	228	if (!err)
	229	ovl_set_timestamps(upperdentry, stat);
	230
	231	return err;
e9be9d5e MS	232	}
	233
	234	static int ovl_copy_up_locked(struct dentry workdir, struct dentry upperdir,
	235	struct dentry dentry, struct path lowerpath,
42f269b9	236	struct kstat stat, const char link,
d8514d8e	237	struct kstat *pstat, bool tmpfile)
e9be9d5e MS	238	{
	239	struct inode *wdir = workdir->d_inode;
	240	struct inode *udir = upperdir->d_inode;
	241	struct dentry *newdentry = NULL;
	242	struct dentry *upper = NULL;
42f269b9	243	struct dentry *temp = NULL;
e9be9d5e	244	int err;
d8ad8b49 VG	245	const struct cred *old_creds = NULL;
d8ad8b49 VG	246	struct cred *new_creds = NULL;
32a3d848 AV	247	struct cattr cattr = {
	248	/* Can't properly set mode on creation because of the umask */
	249	.mode = stat->mode & S_IFMT,
	250	.rdev = stat->rdev,
	251	.link = link
	252	};
e9be9d5e	253
e9be9d5e MS	254	upper = lookup_one_len(dentry->d_name.name, upperdir,
	255	dentry->d_name.len);
	256	err = PTR_ERR(upper);
	257	if (IS_ERR(upper))
42f269b9	258	goto out;
e9be9d5e	259
d8ad8b49 VG	260	err = security_inode_copy_up(dentry, &new_creds);
d8ad8b49 VG	261	if (err < 0)
42f269b9	262	goto out1;
d8ad8b49 VG	263
	264	if (new_creds)
	265	old_creds = override_creds(new_creds);
	266
d8514d8e AG	267	if (tmpfile)
	268	temp = ovl_do_tmpfile(upperdir, stat->mode);
	269	else
	270	temp = ovl_lookup_temp(workdir, dentry);
42f269b9 AG	271	err = PTR_ERR(temp);
	272	if (IS_ERR(temp))
	273	goto out1;
	274
d8514d8e AG	275	err = 0;
	276	if (!tmpfile)
	277	err = ovl_create_real(wdir, temp, &cattr, NULL, true);
d8ad8b49 VG	278
	279	if (new_creds) {
	280	revert_creds(old_creds);
	281	put_cred(new_creds);
	282	}
	283
e9be9d5e MS	284	if (err)
	285	goto out2;
	286
	287	if (S_ISREG(stat->mode)) {
	288	struct path upperpath;
f134f244	289
e9be9d5e MS	290	ovl_path_upper(dentry, &upperpath);
e9be9d5e MS	291	BUG_ON(upperpath.dentry != NULL);
42f269b9	292	upperpath.dentry = temp;
e9be9d5e MS	293
	294	err = ovl_copy_up_data(lowerpath, &upperpath, stat->size);
	295	if (err)
	296	goto out_cleanup;
	297	}
	298
42f269b9	299	err = ovl_copy_xattr(lowerpath->dentry, temp);
e9be9d5e MS	300	if (err)
	301	goto out_cleanup;
	302
42f269b9 AG	303	inode_lock(temp->d_inode);
	304	err = ovl_set_attr(temp, stat);
	305	inode_unlock(temp->d_inode);
e9be9d5e MS	306	if (err)
	307	goto out_cleanup;
	308
d8514d8e AG	309	if (tmpfile)
	310	err = ovl_do_link(temp, udir, upper, true);
	311	else
	312	err = ovl_do_rename(wdir, temp, udir, upper, 0);
e9be9d5e MS	313	if (err)
	314	goto out_cleanup;
	315
d8514d8e	316	newdentry = dget(tmpfile ? upper : temp);
e9be9d5e	317	ovl_dentry_update(dentry, newdentry);
39b681f8	318	ovl_inode_update(d_inode(dentry), d_inode(newdentry));
42f269b9 AG	319
	320	/* Restore timestamps on parent (best effort) */
	321	ovl_set_timestamps(upperdir, pstat);
e9be9d5e	322	out2:
42f269b9	323	dput(temp);
e9be9d5e	324	out1:
42f269b9	325	dput(upper);
e9be9d5e MS	326	out:
	327	return err;
	328
	329	out_cleanup:
d8514d8e AG	330	if (!tmpfile)
d8514d8e AG	331	ovl_cleanup(wdir, temp);
ab79efab	332	goto out2;
e9be9d5e MS	333	}
	334
	335	/*
	336	* Copy up a single dentry
	337	*
a6c60655 MS	338	* All renames start with copy up of source if necessary. The actual
	339	* rename will only proceed once the copy up was successful. Copy up uses
	340	* upper parent i_mutex for exclusion. Since rename can change d_parent it
	341	* is possible that the copy up will lock the old parent. At that point
	342	* the file will have already been copied up anyway.
e9be9d5e	343	*/
9aba6521 AG	344	static int ovl_copy_up_one(struct dentry parent, struct dentry dentry,
9aba6521 AG	345	struct path lowerpath, struct kstat stat)
e9be9d5e	346	{
7764235b	347	DEFINE_DELAYED_CALL(done);
e9be9d5e MS	348	struct dentry *workdir = ovl_workdir(dentry);
	349	int err;
	350	struct kstat pstat;
	351	struct path parentpath;
7764235b	352	struct dentry *lowerdentry = lowerpath->dentry;
e9be9d5e	353	struct dentry *upperdir;
7764235b	354	const char *link = NULL;
d8514d8e AG	355	struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
	356	/* Should we copyup with O_TMPFILE or with workdir? */
	357	bool tmpfile = S_ISREG(stat->mode) && ofs->tmpfile;
e9be9d5e	358
cc6f67bc MS	359	if (WARN_ON(!workdir))
	360	return -EROFS;
	361
7764235b	362	ovl_do_check_copy_up(lowerdentry);
fb5bb2c3	363
e9be9d5e MS	364	ovl_path_upper(parent, &parentpath);
	365	upperdir = parentpath.dentry;
	366
	367	err = vfs_getattr(&parentpath, &pstat);
	368	if (err)
	369	return err;
	370
	371	if (S_ISLNK(stat->mode)) {
7764235b	372	link = vfs_get_link(lowerdentry, &done);
e9be9d5e MS	373	if (IS_ERR(link))
	374	return PTR_ERR(link);
	375	}
	376
e9be9d5e MS	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	}
a6c60655	382	if (ovl_dentry_upper(dentry)) {
0f7ff2da	383	/* Raced with another copy-up? Nothing to do, then... */
e9be9d5e	384	err = 0;
0f7ff2da	385	goto out_unlock;
e9be9d5e MS	386	}
	387
	388	err = ovl_copy_up_locked(workdir, upperdir, dentry, lowerpath,
d8514d8e	389	stat, link, &pstat, tmpfile);
e9be9d5e MS	390	out_unlock:
e9be9d5e MS	391	unlock_rename(workdir, upperdir);
7764235b	392	do_delayed_call(&done);
e9be9d5e MS	393
	394	return err;
	395	}
	396
9aba6521	397	int ovl_copy_up_flags(struct dentry *dentry, int flags)
e9be9d5e	398	{
8eac98b8 VG	399	int err = 0;
8eac98b8 VG	400	const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
e9be9d5e	401
e9be9d5e MS	402	while (!err) {
	403	struct dentry *next;
	404	struct dentry *parent;
	405	struct path lowerpath;
	406	struct kstat stat;
	407	enum ovl_path_type type = ovl_path_type(dentry);
	408
1afaba1e	409	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	410	break;
	411
	412	next = dget(dentry);
	413	/* find the topmost dentry not yet copied up */
	414	for (;;) {
	415	parent = dget_parent(next);
	416
	417	type = ovl_path_type(parent);
1afaba1e	418	if (OVL_TYPE_UPPER(type))
e9be9d5e MS	419	break;
	420
	421	dput(next);
	422	next = parent;
	423	}
	424
	425	ovl_path_lower(next, &lowerpath);
	426	err = vfs_getattr(&lowerpath, &stat);
9aba6521 AG	427	/* maybe truncate regular file. this has no effect on dirs */
	428	if (flags & O_TRUNC)
	429	stat.size = 0;
e9be9d5e	430	if (!err)
0f7ff2da	431	err = ovl_copy_up_one(parent, next, &lowerpath, &stat);
e9be9d5e MS	432
	433	dput(parent);
	434	dput(next);
	435	}
8eac98b8	436	revert_creds(old_cred);
e9be9d5e MS	437
	438	return err;
	439	}
9aba6521 AG	440
	441	int ovl_copy_up(struct dentry *dentry)
	442	{
	443	return ovl_copy_up_flags(dentry, 0);
	444	}