[linux-2.6-block.git] / drivers / base / devtmpfs.c

// SPDX-License-Identifier: GPL-2.0
/*
 * devtmpfs - kernel-maintained tmpfs-based /dev
 *
 * Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
 *
 * 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 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>
#include <uapi/linux/mount.h>
#include "base.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 */
	kuid_t uid;
	kgid_t gid;
	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 vfsmount *mnt;

static struct dentry *public_dev_mount(struct file_system_type *fs_type, int flags,
		      const char *dev_name, void *data)
{
	struct super_block *s = mnt->mnt_sb;
	atomic_inc(&s->s_active);
	down_write(&s->s_umount);
	return dget(s->s_root);
}

static struct file_system_type internal_fs_type = {
	.name = "devtmpfs",
#ifdef CONFIG_TMPFS
	.init_fs_context = shmem_init_fs_context,
	.parameters	= &shmem_fs_parameters,
#else
	.init_fs_context = ramfs_init_fs_context,
	.parameters	= &ramfs_fs_parameters,
#endif
	.kill_sb = kill_litter_super,
};

static struct file_system_type dev_fs_type = {
	.name = "devtmpfs",
	.mount = public_dev_mount,
};

#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.uid = GLOBAL_ROOT_UID;
	req.gid = GLOBAL_ROOT_GID;
	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &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, NULL, 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, LOOKUP_DIRECTORY);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
	if (!err)
		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	done_path_create(&path, dentry);
	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, kuid_t uid,
			 kgid_t gid, 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(d_inode(path.dentry), dentry, mode, dev->devt);
	if (!err) {
		struct iattr newattrs;

		newattrs.ia_mode = mode;
		newattrs.ia_uid = uid;
		newattrs.ia_gid = gid;
		newattrs.ia_valid = ATTR_MODE|ATTR_UID|ATTR_GID;
		inode_lock(d_inode(dentry));
		notify_change(dentry, &newattrs, NULL);
		inode_unlock(d_inode(dentry));

		/* mark as kernel-created inode */
		d_inode(dentry)->i_private = &thread;
	}
	done_path_create(&path, dentry);
	return err;
}

static int dev_rmdir(const char *name)
{
	struct path parent;
	struct dentry *dentry;
	int err;

	dentry = kern_path_locked(name, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	if (d_really_is_positive(dentry)) {
		if (d_inode(dentry)->i_private == &thread)
			err = vfs_rmdir(d_inode(parent.dentry), dentry);
		else
			err = -EPERM;
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));
	path_put(&parent);
	return err;
}

static int delete_path(const char *nodepath)
{
	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 path parent;
	struct dentry *dentry;
	int deleted = 0;
	int err;

	dentry = kern_path_locked(nodename, &parent);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);

	if (d_really_is_positive(dentry)) {
		struct kstat stat;
		struct path p = {.mnt = parent.mnt, .dentry = dentry};
		err = vfs_getattr(&p, &stat, STATX_TYPE | STATX_MODE,
				  AT_STATX_SYNC_AS_STAT);
		if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
			struct iattr newattrs;
			/*
			 * before unlinking this node, reset permissions
			 * of possible references like hardlinks
			 */
			newattrs.ia_uid = GLOBAL_ROOT_UID;
			newattrs.ia_gid = GLOBAL_ROOT_GID;
			newattrs.ia_mode = stat.mode & ~0777;
			newattrs.ia_valid =
				ATTR_UID|ATTR_GID|ATTR_MODE;
			inode_lock(d_inode(dentry));
			notify_change(dentry, &newattrs, NULL);
			inode_unlock(d_inode(dentry));
			err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
			if (!err || err == -ENOENT)
				deleted = 1;
		}
	} else {
		err = -ENOENT;
	}
	dput(dentry);
	inode_unlock(d_inode(parent.dentry));

	path_put(&parent);
	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 = ksys_mount("devtmpfs", 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, kuid_t uid, kgid_t gid,
		  struct device *dev)
{
	if (mode)
		return handle_create(name, mode, uid, gid, dev);
	else
		return handle_remove(name, dev);
}

static int devtmpfsd(void *p)
{
	int *err = p;
	*err = ksys_unshare(CLONE_NEWNS);
	if (*err)
		goto out;
	*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
	if (*err)
		goto out;
	ksys_chdir("/.."); /* will traverse into overmounted root */
	ksys_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->uid, req->gid, 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)
{
	char opts[] = "mode=0755";
	int err;

	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	if (IS_ERR(mnt)) {
		printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
				PTR_ERR(mnt));
		return PTR_ERR(mnt);
	}
	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
b2441318	1	// SPDX-License-Identifier: GPL-2.0
2b2af54a KS	2	/*
	3	* devtmpfs - kernel-maintained tmpfs-based /dev
	4	*
	5	* Copyright (C) 2009, Kay Sievers <kay.sievers@vrfy.org>
	6	*
	7	* During bootup, before any driver core device is registered,
	8	* devtmpfs, a tmpfs-based filesystem is created. Every driver-core
	9	* device which requests a device node, will add a node in this
e454cea2	10	* filesystem.
02fbe5e6 PK	11	* By default, all devices are named after the name of the device,
	12	* owned by root and have a default mode of 0600. Subsystems can
	13	* overwrite the default setting if needed.
2b2af54a KS	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/syscalls.h>
	18	#include <linux/mount.h>
	19	#include <linux/device.h>
	20	#include <linux/genhd.h>
	21	#include <linux/namei.h>
	22	#include <linux/fs.h>
	23	#include <linux/shmem_fs.h>
da5e4ef7	24	#include <linux/ramfs.h>
e454cea2	25	#include <linux/sched.h>
5a0e3ad6	26	#include <linux/slab.h>
2780f1ff	27	#include <linux/kthread.h>
e262e32d	28	#include <uapi/linux/mount.h>
c3a30420	29	#include "base.h"
2b2af54a	30
2780f1ff	31	static struct task_struct *thread;
2b2af54a KS	32
2b2af54a KS	33	#if defined CONFIG_DEVTMPFS_MOUNT
fc14f2fe	34	static int mount_dev = 1;
2b2af54a	35	#else
fc14f2fe	36	static int mount_dev;
2b2af54a KS	37	#endif
2b2af54a KS	38
2780f1ff AV	39	static DEFINE_SPINLOCK(req_lock);
	40
	41	static struct req {
	42	struct req *next;
	43	struct completion done;
	44	int err;
	45	const char *name;
2c9ede55	46	umode_t mode; /* 0 => delete */
4e4098a3 GKH	47	kuid_t uid;
4e4098a3 GKH	48	kgid_t gid;
2780f1ff AV	49	struct device *dev;
2780f1ff AV	50	} *requests;
ed413ae6	51
2b2af54a KS	52	static int __init mount_param(char *str)
2b2af54a KS	53	{
fc14f2fe	54	mount_dev = simple_strtoul(str, NULL, 0);
2b2af54a KS	55	return 1;
	56	}
	57	__setup("devtmpfs.mount=", mount_param);
	58
d401727e AV	59	static struct vfsmount *mnt;
	60
	61	static struct dentry public_dev_mount(struct file_system_type fs_type, int flags,
	62	const char dev_name, void data)
	63	{
	64	struct super_block *s = mnt->mnt_sb;
	65	atomic_inc(&s->s_active);
	66	down_write(&s->s_umount);
	67	return dget(s->s_root);
	68	}
	69
f3235626 DH	70	static struct file_system_type internal_fs_type = {
f3235626 DH	71	.name = "devtmpfs",
da5e4ef7	72	#ifdef CONFIG_TMPFS
f3235626 DH	73	.init_fs_context = shmem_init_fs_context,
f3235626 DH	74	.parameters = &shmem_fs_parameters,
da5e4ef7	75	#else
f3235626 DH	76	.init_fs_context = ramfs_init_fs_context,
f3235626 DH	77	.parameters = &ramfs_fs_parameters,
da5e4ef7	78	#endif
2b2af54a KS	79	.kill_sb = kill_litter_super,
	80	};
	81
d401727e AV	82	static struct file_system_type dev_fs_type = {
	83	.name = "devtmpfs",
	84	.mount = public_dev_mount,
	85	};
	86
2b2af54a KS	87	#ifdef CONFIG_BLOCK
	88	static inline int is_blockdev(struct device *dev)
	89	{
	90	return dev->class == &block_class;
	91	}
	92	#else
	93	static inline int is_blockdev(struct device *dev) { return 0; }
	94	#endif
	95
2780f1ff AV	96	int devtmpfs_create_node(struct device *dev)
	97	{
	98	const char *tmp = NULL;
	99	struct req req;
	100
	101	if (!thread)
	102	return 0;
	103
	104	req.mode = 0;
4e4098a3 GKH	105	req.uid = GLOBAL_ROOT_UID;
4e4098a3 GKH	106	req.gid = GLOBAL_ROOT_GID;
3c2670e6	107	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
2780f1ff AV	108	if (!req.name)
	109	return -ENOMEM;
	110
	111	if (req.mode == 0)
	112	req.mode = 0600;
	113	if (is_blockdev(dev))
	114	req.mode \|= S_IFBLK;
	115	else
	116	req.mode \|= S_IFCHR;
	117
	118	req.dev = dev;
	119
	120	init_completion(&req.done);
	121
	122	spin_lock(&req_lock);
	123	req.next = requests;
	124	requests = &req;
	125	spin_unlock(&req_lock);
	126
	127	wake_up_process(thread);
	128	wait_for_completion(&req.done);
	129
	130	kfree(tmp);
	131
	132	return req.err;
	133	}
	134
	135	int devtmpfs_delete_node(struct device *dev)
	136	{
	137	const char *tmp = NULL;
	138	struct req req;
	139
	140	if (!thread)
	141	return 0;
	142
3c2670e6	143	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
2780f1ff AV	144	if (!req.name)
	145	return -ENOMEM;
	146
	147	req.mode = 0;
	148	req.dev = dev;
	149
	150	init_completion(&req.done);
	151
	152	spin_lock(&req_lock);
	153	req.next = requests;
	154	requests = &req;
	155	spin_unlock(&req_lock);
	156
	157	wake_up_process(thread);
	158	wait_for_completion(&req.done);
	159
	160	kfree(tmp);
	161	return req.err;
	162	}
	163
fbd48a69	164	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	165	{
2b2af54a	166	struct dentry *dentry;
69753a0f	167	struct path path;
2b2af54a KS	168	int err;
2b2af54a KS	169
1ac12b4b	170	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
69753a0f AV	171	if (IS_ERR(dentry))
	172	return PTR_ERR(dentry);
	173
75c3cfa8	174	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
69753a0f AV	175	if (!err)
69753a0f AV	176	/* mark as kernel-created inode */
75c3cfa8	177	d_inode(dentry)->i_private = &thread;
921a1650	178	done_path_create(&path, dentry);
2b2af54a KS	179	return err;
	180	}
	181
	182	static int create_path(const char *nodepath)
	183	{
5da4e689 AV	184	char *path;
5da4e689 AV	185	char *s;
9d108d25	186	int err = 0;
2b2af54a	187
5da4e689 AV	188	/* parent directories do not exist, create them */
	189	path = kstrdup(nodepath, GFP_KERNEL);
	190	if (!path)
	191	return -ENOMEM;
	192
	193	s = path;
	194	for (;;) {
	195	s = strchr(s, '/');
	196	if (!s)
	197	break;
	198	s[0] = '\0';
	199	err = dev_mkdir(path, 0755);
	200	if (err && err != -EEXIST)
	201	break;
	202	s[0] = '/';
	203	s++;
2b2af54a	204	}
5da4e689	205	kfree(path);
2b2af54a KS	206	return err;
	207	}
	208
4e4098a3 GKH	209	static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
4e4098a3 GKH	210	kgid_t gid, struct device *dev)
2b2af54a	211	{
2b2af54a	212	struct dentry *dentry;
69753a0f	213	struct path path;
2b2af54a KS	214	int err;
2b2af54a KS	215
69753a0f AV	216	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	217	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	218	create_path(nodename);
69753a0f	219	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	220	}
69753a0f AV	221	if (IS_ERR(dentry))
	222	return PTR_ERR(dentry);
	223
75c3cfa8	224	err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
69753a0f AV	225	if (!err) {
	226	struct iattr newattrs;
	227
69753a0f	228	newattrs.ia_mode = mode;
4e4098a3 GKH	229	newattrs.ia_uid = uid;
4e4098a3 GKH	230	newattrs.ia_gid = gid;
3c2670e6	231	newattrs.ia_valid = ATTR_MODE\|ATTR_UID\|ATTR_GID;
5955102c	232	inode_lock(d_inode(dentry));
27ac0ffe	233	notify_change(dentry, &newattrs, NULL);
5955102c	234	inode_unlock(d_inode(dentry));
69753a0f AV	235
69753a0f AV	236	/* mark as kernel-created inode */
75c3cfa8	237	d_inode(dentry)->i_private = &thread;
2b2af54a	238	}
921a1650	239	done_path_create(&path, dentry);
2b2af54a KS	240	return err;
	241	}
	242
	243	static int dev_rmdir(const char *name)
	244	{
79714f72	245	struct path parent;
2b2af54a KS	246	struct dentry *dentry;
	247	int err;
	248
79714f72 AV	249	dentry = kern_path_locked(name, &parent);
	250	if (IS_ERR(dentry))
	251	return PTR_ERR(dentry);
75c3cfa8 DH	252	if (d_really_is_positive(dentry)) {
	253	if (d_inode(dentry)->i_private == &thread)
	254	err = vfs_rmdir(d_inode(parent.dentry), dentry);
79714f72 AV	255	else
79714f72 AV	256	err = -EPERM;
2b2af54a	257	} else {
79714f72	258	err = -ENOENT;
2b2af54a	259	}
79714f72	260	dput(dentry);
5955102c	261	inode_unlock(d_inode(parent.dentry));
79714f72	262	path_put(&parent);
2b2af54a KS	263	return err;
	264	}
	265
	266	static int delete_path(const char *nodepath)
	267	{
be6b1dfe	268	char *path;
2b2af54a KS	269	int err = 0;
	270
	271	path = kstrdup(nodepath, GFP_KERNEL);
	272	if (!path)
	273	return -ENOMEM;
	274
ed413ae6	275	for (;;) {
2b2af54a KS	276	char *base;
	277
	278	base = strrchr(path, '/');
	279	if (!base)
	280	break;
	281	base[0] = '\0';
	282	err = dev_rmdir(path);
	283	if (err)
	284	break;
	285	}
	286
	287	kfree(path);
	288	return err;
	289	}
	290
	291	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	292	{
	293	/* did we create it */
2780f1ff	294	if (inode->i_private != &thread)
2b2af54a KS	295	return 0;
	296
	297	/* does the dev_t match */
	298	if (is_blockdev(dev)) {
	299	if (!S_ISBLK(stat->mode))
	300	return 0;
	301	} else {
	302	if (!S_ISCHR(stat->mode))
	303	return 0;
	304	}
	305	if (stat->rdev != dev->devt)
	306	return 0;
	307
	308	/* ours */
	309	return 1;
	310	}
	311
2780f1ff	312	static int handle_remove(const char nodename, struct device dev)
2b2af54a	313	{
79714f72	314	struct path parent;
2b2af54a	315	struct dentry *dentry;
fbde7c61	316	int deleted = 0;
2b2af54a KS	317	int err;
2b2af54a KS	318
79714f72 AV	319	dentry = kern_path_locked(nodename, &parent);
	320	if (IS_ERR(dentry))
	321	return PTR_ERR(dentry);
	322
75c3cfa8	323	if (d_really_is_positive(dentry)) {
79714f72	324	struct kstat stat;
3dadecce	325	struct path p = {.mnt = parent.mnt, .dentry = dentry};
a528d35e DH	326	err = vfs_getattr(&p, &stat, STATX_TYPE \| STATX_MODE,
a528d35e DH	327	AT_STATX_SYNC_AS_STAT);
75c3cfa8	328	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
79714f72 AV	329	struct iattr newattrs;
	330	/*
	331	* before unlinking this node, reset permissions
	332	* of possible references like hardlinks
	333	*/
91fa2cca EB	334	newattrs.ia_uid = GLOBAL_ROOT_UID;
91fa2cca EB	335	newattrs.ia_gid = GLOBAL_ROOT_GID;
79714f72 AV	336	newattrs.ia_mode = stat.mode & ~0777;
	337	newattrs.ia_valid =
	338	ATTR_UID\|ATTR_GID\|ATTR_MODE;
5955102c	339	inode_lock(d_inode(dentry));
27ac0ffe	340	notify_change(dentry, &newattrs, NULL);
5955102c	341	inode_unlock(d_inode(dentry));
75c3cfa8	342	err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
79714f72 AV	343	if (!err \|\| err == -ENOENT)
79714f72 AV	344	deleted = 1;
2b2af54a	345	}
2b2af54a	346	} else {
79714f72	347	err = -ENOENT;
2b2af54a	348	}
79714f72	349	dput(dentry);
5955102c	350	inode_unlock(d_inode(parent.dentry));
2b2af54a	351
79714f72	352	path_put(&parent);
2b2af54a KS	353	if (deleted && strchr(nodename, '/'))
2b2af54a KS	354	delete_path(nodename);
2b2af54a KS	355	return err;
	356	}
	357
	358	/*
	359	* If configured, or requested by the commandline, devtmpfs will be
	360	* auto-mounted after the kernel mounted the root filesystem.
	361	*/
073120cc	362	int devtmpfs_mount(const char *mntdir)
2b2af54a	363	{
2b2af54a KS	364	int err;
2b2af54a KS	365
fc14f2fe	366	if (!mount_dev)
2b2af54a KS	367	return 0;
2b2af54a KS	368
2780f1ff	369	if (!thread)
2b2af54a KS	370	return 0;
2b2af54a KS	371
33488845	372	err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
2b2af54a KS	373	if (err)
	374	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	375	else
	376	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	377	return err;
	378	}
	379
f9e0b159	380	static DECLARE_COMPLETION(setup_done);
2780f1ff	381
4e4098a3	382	static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
3c2670e6	383	struct device *dev)
2780f1ff AV	384	{
2780f1ff AV	385	if (mode)
3c2670e6	386	return handle_create(name, mode, uid, gid, dev);
2780f1ff AV	387	else
	388	return handle_remove(name, dev);
	389	}
	390
	391	static int devtmpfsd(void *p)
	392	{
2780f1ff	393	int *err = p;
9b32105e	394	*err = ksys_unshare(CLONE_NEWNS);
2780f1ff AV	395	if (*err)
2780f1ff AV	396	goto out;
d401727e	397	*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
2780f1ff AV	398	if (*err)
2780f1ff AV	399	goto out;
447016e9	400	ksys_chdir("/.."); /* will traverse into overmounted root */
a16fe33a	401	ksys_chroot(".");
2780f1ff AV	402	complete(&setup_done);
	403	while (1) {
	404	spin_lock(&req_lock);
	405	while (requests) {
	406	struct req *req = requests;
	407	requests = NULL;
	408	spin_unlock(&req_lock);
	409	while (req) {
e13889ba	410	struct req *next = req->next;
3c2670e6 KS	411	req->err = handle(req->name, req->mode,
3c2670e6 KS	412	req->uid, req->gid, req->dev);
2780f1ff	413	complete(&req->done);
e13889ba	414	req = next;
2780f1ff AV	415	}
	416	spin_lock(&req_lock);
	417	}
65e6757b	418	__set_current_state(TASK_INTERRUPTIBLE);
2780f1ff AV	419	spin_unlock(&req_lock);
2780f1ff AV	420	schedule();
2780f1ff AV	421	}
	422	return 0;
	423	out:
	424	complete(&setup_done);
	425	return *err;
	426	}
	427
2b2af54a KS	428	/*
	429	* Create devtmpfs instance, driver-core devices will add their device
	430	* nodes here.
	431	*/
	432	int __init devtmpfs_init(void)
	433	{
d401727e AV	434	char opts[] = "mode=0755";
	435	int err;
	436
	437	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	438	if (IS_ERR(mnt)) {
	439	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
	440	PTR_ERR(mnt));
	441	return PTR_ERR(mnt);
	442	}
	443	err = register_filesystem(&dev_fs_type);
2b2af54a KS	444	if (err) {
	445	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	446	"type %i\n", err);
	447	return err;
	448	}
	449
2780f1ff AV	450	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	451	if (!IS_ERR(thread)) {
	452	wait_for_completion(&setup_done);
	453	} else {
	454	err = PTR_ERR(thread);
	455	thread = NULL;
	456	}
	457
	458	if (err) {
2b2af54a KS	459	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	460	unregister_filesystem(&dev_fs_type);
	461	return err;
	462	}
2b2af54a KS	463
	464	printk(KERN_INFO "devtmpfs: initialized\n");
	465	return 0;
	466	}