[linux.git] / drivers / base / devtmpfs.c

/*
 * devtmpfs - kernel-maintained tmpfs-based /dev
 *
 * Copyright (C) 2009, Kay Sievers <[email protected]>
 *
 * During bootup, before any driver core device is registered,
 * devtmpfs, a tmpfs-based filesystem is created. Every driver-core
 * device which requests a device node, will add a node in this
 * filesystem.
 * By default, all devices are named after the the name of the
 * device, owned by root and have a default mode of 0600. Subsystems
 * can overwrite the default setting if needed.
 */

#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/mount.h>
#include <linux/device.h>
#include <linux/genhd.h>
#include <linux/namei.h>
#include <linux/fs.h>
#include <linux/shmem_fs.h>
#include <linux/ramfs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/kthread.h>

static struct task_struct *thread;

#if defined CONFIG_DEVTMPFS_MOUNT
static int mount_dev = 1;
#else
static int mount_dev;
#endif

static DEFINE_SPINLOCK(req_lock);

static struct req {
	struct req *next;
	struct completion done;
	int err;
	const char *name;
	umode_t mode;	/* 0 => delete */
	struct device *dev;
} *requests;

static int __init mount_param(char *str)
{
	mount_dev = simple_strtoul(str, NULL, 0);
	return 1;
}
__setup("devtmpfs.mount=", mount_param);

static struct dentry *dev_mount(struct file_system_type *fs_type, int flags,
		      const char *dev_name, void *data)
{
#ifdef CONFIG_TMPFS
	return mount_single(fs_type, flags, data, shmem_fill_super);
#else
	return mount_single(fs_type, flags, data, ramfs_fill_super);
#endif
}

static struct file_system_type dev_fs_type = {
	.name = "devtmpfs",
	.mount = dev_mount,
	.kill_sb = kill_litter_super,
};

#ifdef CONFIG_BLOCK
static inline int is_blockdev(struct device *dev)
{
	return dev->class == &block_class;
}
#else
static inline int is_blockdev(struct device *dev) { return 0; }
#endif

int devtmpfs_create_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.mode = 0;
	req.name = device_get_devnode(dev, &req.mode, &tmp);
	if (!req.name)
		return -ENOMEM;

	if (req.mode == 0)
		req.mode = 0600;
	if (is_blockdev(dev))
		req.mode |= S_IFBLK;
	else
		req.mode |= S_IFCHR;

	req.dev = dev;

	init_completion(&req.done);

	spin_lock(&req_lock);
	req.next = requests;
	requests = &req;
	spin_unlock(&req_lock);

	wake_up_process(thread);
	wait_for_completion(&req.done);

	kfree(tmp);

	return req.err;
}

int devtmpfs_delete_node(struct device *dev)
{
	const char *tmp = NULL;
	struct req req;

	if (!thread)
		return 0;

	req.name = device_get_devnode(dev, NULL, &tmp);
	if (!req.name)
		return -ENOMEM;

	req.mode = 0;
	req.dev = dev;

	init_completion(&req.done);

	spin_lock(&req_lock);
	req.next = requests;
	requests = &req;
	spin_unlock(&req_lock);

	wake_up_process(thread);
	wait_for_completion(&req.done);

	kfree(tmp);
	return req.err;
}

static int dev_mkdir(const char *name, umode_t mode)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, name, &path, 1);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mkdir(path.dentry->d_inode, dentry, mode);
	if (!err)
		/* mark as kernel-created inode */
		dentry->d_inode->i_private = &thread;
	dput(dentry);
	mutex_unlock(&path.dentry->d_inode->i_mutex);
	path_put(&path);
	return err;
}

static int create_path(const char *nodepath)
{
	char *path;
	char *s;
	int err = 0;

	/* parent directories do not exist, create them */
	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	s = path;
	for (;;) {
		s = strchr(s, '/');
		if (!s)
			break;
		s[0] = '\0';
		err = dev_mkdir(path, 0755);
		if (err && err != -EEXIST)
			break;
		s[0] = '/';
		s++;
	}
	kfree(path);
	return err;
}

static int handle_create(const char *nodename, umode_t mode, struct device *dev)
{
	struct dentry *dentry;
	struct path path;
	int err;

	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	if (dentry == ERR_PTR(-ENOENT)) {
		create_path(nodename);
		dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
	}
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mknod(path.dentry->d_inode,
			dentry, mode, dev->devt);
	if (!err) {
		struct iattr newattrs;

		/* fixup possibly umasked mode */
		newattrs.ia_mode = mode;
		newattrs.ia_valid = ATTR_MODE;
		mutex_lock(&dentry->d_inode->i_mutex);
		notify_change(dentry, &newattrs);
		mutex_unlock(&dentry->d_inode->i_mutex);

		/* mark as kernel-created inode */
		dentry->d_inode->i_private = &thread;
	}
	dput(dentry);

	mutex_unlock(&path.dentry->d_inode->i_mutex);
	path_put(&path);
	return err;
}

static int dev_rmdir(const char *name)
{
	struct nameidata nd;
	struct dentry *dentry;
	int err;

	err = kern_path_parent(name, &nd);
	if (err)
		return err;

	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	if (!IS_ERR(dentry)) {
		if (dentry->d_inode) {
			if (dentry->d_inode->i_private == &thread)
				err = vfs_rmdir(nd.path.dentry->d_inode,
						dentry);
			else
				err = -EPERM;
		} else {
			err = -ENOENT;
		}
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}

	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	path_put(&nd.path);
	return err;
}

static int delete_path(const char *nodepath)
{
	const char *path;
	int err = 0;

	path = kstrdup(nodepath, GFP_KERNEL);
	if (!path)
		return -ENOMEM;

	for (;;) {
		char *base;

		base = strrchr(path, '/');
		if (!base)
			break;
		base[0] = '\0';
		err = dev_rmdir(path);
		if (err)
			break;
	}

	kfree(path);
	return err;
}

static int dev_mynode(struct device *dev, struct inode *inode, struct kstat *stat)
{
	/* did we create it */
	if (inode->i_private != &thread)
		return 0;

	/* does the dev_t match */
	if (is_blockdev(dev)) {
		if (!S_ISBLK(stat->mode))
			return 0;
	} else {
		if (!S_ISCHR(stat->mode))
			return 0;
	}
	if (stat->rdev != dev->devt)
		return 0;

	/* ours */
	return 1;
}

static int handle_remove(const char *nodename, struct device *dev)
{
	struct nameidata nd;
	struct dentry *dentry;
	struct kstat stat;
	int deleted = 1;
	int err;

	err = kern_path_parent(nodename, &nd);
	if (err)
		return err;

	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	if (!IS_ERR(dentry)) {
		if (dentry->d_inode) {
			err = vfs_getattr(nd.path.mnt, dentry, &stat);
			if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
				struct iattr newattrs;
				/*
				 * before unlinking this node, reset permissions
				 * of possible references like hardlinks
				 */
				newattrs.ia_uid = 0;
				newattrs.ia_gid = 0;
				newattrs.ia_mode = stat.mode & ~0777;
				newattrs.ia_valid =
					ATTR_UID|ATTR_GID|ATTR_MODE;
				mutex_lock(&dentry->d_inode->i_mutex);
				notify_change(dentry, &newattrs);
				mutex_unlock(&dentry->d_inode->i_mutex);
				err = vfs_unlink(nd.path.dentry->d_inode,
						 dentry);
				if (!err || err == -ENOENT)
					deleted = 1;
			}
		} else {
			err = -ENOENT;
		}
		dput(dentry);
	} else {
		err = PTR_ERR(dentry);
	}
	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);

	path_put(&nd.path);
	if (deleted && strchr(nodename, '/'))
		delete_path(nodename);
	return err;
}

/*
 * If configured, or requested by the commandline, devtmpfs will be
 * auto-mounted after the kernel mounted the root filesystem.
 */
int devtmpfs_mount(const char *mntdir)
{
	int err;

	if (!mount_dev)
		return 0;

	if (!thread)
		return 0;

	err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
	if (err)
		printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	else
		printk(KERN_INFO "devtmpfs: mounted\n");
	return err;
}

static DECLARE_COMPLETION(setup_done);

static int handle(const char *name, umode_t mode, struct device *dev)
{
	if (mode)
		return handle_create(name, mode, dev);
	else
		return handle_remove(name, dev);
}

static int devtmpfsd(void *p)
{
	char options[] = "mode=0755";
	int *err = p;
	*err = sys_unshare(CLONE_NEWNS);
	if (*err)
		goto out;
	*err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
	if (*err)
		goto out;
	sys_chdir("/.."); /* will traverse into overmounted root */
	sys_chroot(".");
	complete(&setup_done);
	while (1) {
		spin_lock(&req_lock);
		while (requests) {
			struct req *req = requests;
			requests = NULL;
			spin_unlock(&req_lock);
			while (req) {
				struct req *next = req->next;
				req->err = handle(req->name, req->mode, req->dev);
				complete(&req->done);
				req = next;
			}
			spin_lock(&req_lock);
		}
		__set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock(&req_lock);
		schedule();
	}
	return 0;
out:
	complete(&setup_done);
	return *err;
}

/*
 * Create devtmpfs instance, driver-core devices will add their device
 * nodes here.
 */
int __init devtmpfs_init(void)
{
	int err = register_filesystem(&dev_fs_type);
	if (err) {
		printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
		       "type %i\n", err);
		return err;
	}

	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	if (!IS_ERR(thread)) {
		wait_for_completion(&setup_done);
	} else {
		err = PTR_ERR(thread);
		thread = NULL;
	}

	if (err) {
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
		unregister_filesystem(&dev_fs_type);
		return err;
	}

	printk(KERN_INFO "devtmpfs: initialized\n");
	return 0;
}
Commit	Line	Data
2b2af54a KS	1	/*
	2	* devtmpfs - kernel-maintained tmpfs-based /dev
	3	*
	4	* Copyright (C) 2009, Kay Sievers <[email protected]>
	5	*
	6	* During bootup, before any driver core device is registered,
	7	* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
	8	* device which requests a device node, will add a node in this
e454cea2 KS	9	* filesystem.
	10	* By default, all devices are named after the the name of the
	11	* device, owned by root and have a default mode of 0600. Subsystems
	12	* can overwrite the default setting if needed.
2b2af54a KS	13	*/
	14
	15	#include <linux/kernel.h>
	16	#include <linux/syscalls.h>
	17	#include <linux/mount.h>
	18	#include <linux/device.h>
	19	#include <linux/genhd.h>
	20	#include <linux/namei.h>
	21	#include <linux/fs.h>
	22	#include <linux/shmem_fs.h>
da5e4ef7	23	#include <linux/ramfs.h>
e454cea2	24	#include <linux/sched.h>
5a0e3ad6	25	#include <linux/slab.h>
2780f1ff	26	#include <linux/kthread.h>
2b2af54a	27
2780f1ff	28	static struct task_struct *thread;
2b2af54a KS	29
2b2af54a KS	30	#if defined CONFIG_DEVTMPFS_MOUNT
fc14f2fe	31	static int mount_dev = 1;
2b2af54a	32	#else
fc14f2fe	33	static int mount_dev;
2b2af54a KS	34	#endif
2b2af54a KS	35
2780f1ff AV	36	static DEFINE_SPINLOCK(req_lock);
	37
	38	static struct req {
	39	struct req *next;
	40	struct completion done;
	41	int err;
	42	const char *name;
2c9ede55	43	umode_t mode; /* 0 => delete */
2780f1ff AV	44	struct device *dev;
2780f1ff AV	45	} *requests;
ed413ae6	46
2b2af54a KS	47	static int __init mount_param(char *str)
2b2af54a KS	48	{
fc14f2fe	49	mount_dev = simple_strtoul(str, NULL, 0);
2b2af54a KS	50	return 1;
	51	}
	52	__setup("devtmpfs.mount=", mount_param);
	53
fc14f2fe AV	54	static struct dentry dev_mount(struct file_system_type fs_type, int flags,
fc14f2fe AV	55	const char dev_name, void data)
2b2af54a	56	{
da5e4ef7	57	#ifdef CONFIG_TMPFS
fc14f2fe	58	return mount_single(fs_type, flags, data, shmem_fill_super);
da5e4ef7	59	#else
fc14f2fe	60	return mount_single(fs_type, flags, data, ramfs_fill_super);
da5e4ef7	61	#endif
2b2af54a KS	62	}
	63
	64	static struct file_system_type dev_fs_type = {
	65	.name = "devtmpfs",
fc14f2fe	66	.mount = dev_mount,
2b2af54a KS	67	.kill_sb = kill_litter_super,
	68	};
	69
	70	#ifdef CONFIG_BLOCK
	71	static inline int is_blockdev(struct device *dev)
	72	{
	73	return dev->class == &block_class;
	74	}
	75	#else
	76	static inline int is_blockdev(struct device *dev) { return 0; }
	77	#endif
	78
2780f1ff AV	79	int devtmpfs_create_node(struct device *dev)
	80	{
	81	const char *tmp = NULL;
	82	struct req req;
	83
	84	if (!thread)
	85	return 0;
	86
	87	req.mode = 0;
	88	req.name = device_get_devnode(dev, &req.mode, &tmp);
	89	if (!req.name)
	90	return -ENOMEM;
	91
	92	if (req.mode == 0)
	93	req.mode = 0600;
	94	if (is_blockdev(dev))
	95	req.mode \|= S_IFBLK;
	96	else
	97	req.mode \|= S_IFCHR;
	98
	99	req.dev = dev;
	100
	101	init_completion(&req.done);
	102
	103	spin_lock(&req_lock);
	104	req.next = requests;
	105	requests = &req;
	106	spin_unlock(&req_lock);
	107
	108	wake_up_process(thread);
	109	wait_for_completion(&req.done);
	110
	111	kfree(tmp);
	112
	113	return req.err;
	114	}
	115
	116	int devtmpfs_delete_node(struct device *dev)
	117	{
	118	const char *tmp = NULL;
	119	struct req req;
	120
	121	if (!thread)
	122	return 0;
	123
	124	req.name = device_get_devnode(dev, NULL, &tmp);
	125	if (!req.name)
	126	return -ENOMEM;
	127
	128	req.mode = 0;
	129	req.dev = dev;
	130
	131	init_completion(&req.done);
	132
	133	spin_lock(&req_lock);
	134	req.next = requests;
	135	requests = &req;
	136	spin_unlock(&req_lock);
	137
	138	wake_up_process(thread);
	139	wait_for_completion(&req.done);
	140
	141	kfree(tmp);
	142	return req.err;
143	}
144
fbd48a69	145	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	146	{
2b2af54a	147	struct dentry *dentry;
69753a0f	148	struct path path;
2b2af54a KS	149	int err;
2b2af54a KS	150
69753a0f AV	151	dentry = kern_path_create(AT_FDCWD, name, &path, 1);
	152	if (IS_ERR(dentry))
	153	return PTR_ERR(dentry);
	154
	155	err = vfs_mkdir(path.dentry->d_inode, dentry, mode);
	156	if (!err)
	157	/* mark as kernel-created inode */
	158	dentry->d_inode->i_private = &thread;
	159	dput(dentry);
	160	mutex_unlock(&path.dentry->d_inode->i_mutex);
	161	path_put(&path);
2b2af54a KS	162	return err;
	163	}
	164
	165	static int create_path(const char *nodepath)
	166	{
5da4e689 AV	167	char *path;
5da4e689 AV	168	char *s;
9d108d25	169	int err = 0;
2b2af54a	170
5da4e689 AV	171	/* parent directories do not exist, create them */
	172	path = kstrdup(nodepath, GFP_KERNEL);
	173	if (!path)
	174	return -ENOMEM;
	175
	176	s = path;
	177	for (;;) {
	178	s = strchr(s, '/');
	179	if (!s)
	180	break;
	181	s[0] = '\0';
	182	err = dev_mkdir(path, 0755);
	183	if (err && err != -EEXIST)
	184	break;
	185	s[0] = '/';
	186	s++;
2b2af54a	187	}
5da4e689	188	kfree(path);
2b2af54a KS	189	return err;
	190	}
	191
fbd48a69	192	static int handle_create(const char nodename, umode_t mode, struct device dev)
2b2af54a	193	{
2b2af54a	194	struct dentry *dentry;
69753a0f	195	struct path path;
2b2af54a KS	196	int err;
2b2af54a KS	197
69753a0f AV	198	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	199	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	200	create_path(nodename);
69753a0f	201	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	202	}
69753a0f AV	203	if (IS_ERR(dentry))
	204	return PTR_ERR(dentry);
	205
	206	err = vfs_mknod(path.dentry->d_inode,
	207	dentry, mode, dev->devt);
	208	if (!err) {
	209	struct iattr newattrs;
	210
	211	/* fixup possibly umasked mode */
	212	newattrs.ia_mode = mode;
	213	newattrs.ia_valid = ATTR_MODE;
	214	mutex_lock(&dentry->d_inode->i_mutex);
	215	notify_change(dentry, &newattrs);
	216	mutex_unlock(&dentry->d_inode->i_mutex);
	217
	218	/* mark as kernel-created inode */
	219	dentry->d_inode->i_private = &thread;
2b2af54a	220	}
69753a0f	221	dput(dentry);
2b2af54a	222
69753a0f AV	223	mutex_unlock(&path.dentry->d_inode->i_mutex);
69753a0f AV	224	path_put(&path);
2b2af54a KS	225	return err;
	226	}
	227
	228	static int dev_rmdir(const char *name)
	229	{
	230	struct nameidata nd;
	231	struct dentry *dentry;
	232	int err;
	233
2780f1ff	234	err = kern_path_parent(name, &nd);
2b2af54a KS	235	if (err)
	236	return err;
	237
	238	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	239	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	240	if (!IS_ERR(dentry)) {
015bf43b	241	if (dentry->d_inode) {
2780f1ff	242	if (dentry->d_inode->i_private == &thread)
015bf43b KS	243	err = vfs_rmdir(nd.path.dentry->d_inode,
	244	dentry);
	245	else
	246	err = -EPERM;
	247	} else {
2b2af54a	248	err = -ENOENT;
015bf43b	249	}
2b2af54a KS	250	dput(dentry);
	251	} else {
	252	err = PTR_ERR(dentry);
	253	}
2b2af54a	254
015bf43b	255	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
2b2af54a KS	256	path_put(&nd.path);
	257	return err;
	258	}
	259
	260	static int delete_path(const char *nodepath)
	261	{
	262	const char *path;
	263	int err = 0;
	264
	265	path = kstrdup(nodepath, GFP_KERNEL);
	266	if (!path)
	267	return -ENOMEM;
	268
ed413ae6	269	for (;;) {
2b2af54a KS	270	char *base;
	271
	272	base = strrchr(path, '/');
	273	if (!base)
	274	break;
	275	base[0] = '\0';
	276	err = dev_rmdir(path);
	277	if (err)
	278	break;
	279	}
	280
	281	kfree(path);
	282	return err;
	283	}
	284
	285	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	286	{
	287	/* did we create it */
2780f1ff	288	if (inode->i_private != &thread)
2b2af54a KS	289	return 0;
	290
	291	/* does the dev_t match */
	292	if (is_blockdev(dev)) {
	293	if (!S_ISBLK(stat->mode))
	294	return 0;
	295	} else {
	296	if (!S_ISCHR(stat->mode))
	297	return 0;
	298	}
	299	if (stat->rdev != dev->devt)
	300	return 0;
	301
	302	/* ours */
	303	return 1;
	304	}
	305
2780f1ff	306	static int handle_remove(const char nodename, struct device dev)
2b2af54a	307	{
2b2af54a KS	308	struct nameidata nd;
	309	struct dentry *dentry;
	310	struct kstat stat;
	311	int deleted = 1;
	312	int err;
	313
2780f1ff	314	err = kern_path_parent(nodename, &nd);
2b2af54a	315	if (err)
2780f1ff	316	return err;
2b2af54a KS	317
	318	mutex_lock_nested(&nd.path.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
	319	dentry = lookup_one_len(nd.last.name, nd.path.dentry, nd.last.len);
	320	if (!IS_ERR(dentry)) {
	321	if (dentry->d_inode) {
	322	err = vfs_getattr(nd.path.mnt, dentry, &stat);
	323	if (!err && dev_mynode(dev, dentry->d_inode, &stat)) {
5e31d76f KS	324	struct iattr newattrs;
	325	/*
	326	* before unlinking this node, reset permissions
	327	* of possible references like hardlinks
	328	*/
	329	newattrs.ia_uid = 0;
	330	newattrs.ia_gid = 0;
	331	newattrs.ia_mode = stat.mode & ~0777;
	332	newattrs.ia_valid =
	333	ATTR_UID\|ATTR_GID\|ATTR_MODE;
	334	mutex_lock(&dentry->d_inode->i_mutex);
	335	notify_change(dentry, &newattrs);
	336	mutex_unlock(&dentry->d_inode->i_mutex);
2b2af54a KS	337	err = vfs_unlink(nd.path.dentry->d_inode,
	338	dentry);
	339	if (!err \|\| err == -ENOENT)
	340	deleted = 1;
	341	}
	342	} else {
	343	err = -ENOENT;
	344	}
	345	dput(dentry);
	346	} else {
	347	err = PTR_ERR(dentry);
	348	}
	349	mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
	350
	351	path_put(&nd.path);
	352	if (deleted && strchr(nodename, '/'))
	353	delete_path(nodename);
2b2af54a KS	354	return err;
	355	}
	356
	357	/*
	358	* If configured, or requested by the commandline, devtmpfs will be
	359	* auto-mounted after the kernel mounted the root filesystem.
	360	*/
073120cc	361	int devtmpfs_mount(const char *mntdir)
2b2af54a	362	{
2b2af54a KS	363	int err;
2b2af54a KS	364
fc14f2fe	365	if (!mount_dev)
2b2af54a KS	366	return 0;
2b2af54a KS	367
2780f1ff	368	if (!thread)
2b2af54a KS	369	return 0;
2b2af54a KS	370
073120cc	371	err = sys_mount("devtmpfs", (char *)mntdir, "devtmpfs", MS_SILENT, NULL);
2b2af54a KS	372	if (err)
	373	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	374	else
	375	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	376	return err;
	377	}
	378
f9e0b159	379	static DECLARE_COMPLETION(setup_done);
2780f1ff	380
fbd48a69	381	static int handle(const char name, umode_t mode, struct device dev)
2780f1ff AV	382	{
	383	if (mode)
	384	return handle_create(name, mode, dev);
	385	else
	386	return handle_remove(name, dev);
	387	}
	388
	389	static int devtmpfsd(void *p)
	390	{
	391	char options[] = "mode=0755";
	392	int *err = p;
	393	*err = sys_unshare(CLONE_NEWNS);
	394	if (*err)
	395	goto out;
	396	*err = sys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, options);
	397	if (*err)
	398	goto out;
	399	sys_chdir("/.."); /* will traverse into overmounted root */
	400	sys_chroot(".");
	401	complete(&setup_done);
	402	while (1) {
	403	spin_lock(&req_lock);
	404	while (requests) {
	405	struct req *req = requests;
	406	requests = NULL;
	407	spin_unlock(&req_lock);
	408	while (req) {
e13889ba	409	struct req *next = req->next;
2780f1ff AV	410	req->err = handle(req->name, req->mode, req->dev);
2780f1ff AV	411	complete(&req->done);
e13889ba	412	req = next;
2780f1ff AV	413	}
	414	spin_lock(&req_lock);
	415	}
65e6757b	416	__set_current_state(TASK_INTERRUPTIBLE);
2780f1ff AV	417	spin_unlock(&req_lock);
2780f1ff AV	418	schedule();
2780f1ff AV	419	}
	420	return 0;
	421	out:
	422	complete(&setup_done);
	423	return *err;
	424	}
	425
2b2af54a KS	426	/*
	427	* Create devtmpfs instance, driver-core devices will add their device
	428	* nodes here.
	429	*/
	430	int __init devtmpfs_init(void)
	431	{
2780f1ff	432	int err = register_filesystem(&dev_fs_type);
2b2af54a KS	433	if (err) {
	434	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	435	"type %i\n", err);
	436	return err;
	437	}
	438
2780f1ff AV	439	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	440	if (!IS_ERR(thread)) {
	441	wait_for_completion(&setup_done);
	442	} else {
	443	err = PTR_ERR(thread);
	444	thread = NULL;
	445	}
	446
	447	if (err) {
2b2af54a KS	448	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	449	unregister_filesystem(&dev_fs_type);
	450	return err;
	451	}
2b2af54a KS	452
	453	printk(KERN_INFO "devtmpfs: initialized\n");
	454	return 0;
	455	}