[linux-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 <linux/init_syscalls.h>
#include <uapi/linux/mount.h>
#include "base.h"

static struct task_struct *thread;

static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);

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

static int devtmpfs_submit_req(struct req *req, const char *tmp)
{
	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_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;

	return devtmpfs_submit_req(&req, tmp);
}

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;

	return devtmpfs_submit_req(&req, tmp);
}

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(&init_user_ns, 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(&init_user_ns, 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 __init devtmpfs_mount(void)
{
	int err;

	if (!mount_dev)
		return 0;

	if (!thread)
		return 0;

	err = init_mount("devtmpfs", "dev", "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 void __noreturn devtmpfs_work_loop(void)
{
	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();
	}
}

static int __init devtmpfs_setup(void *p)
{
	int err;

	err = ksys_unshare(CLONE_NEWNS);
	if (err)
		goto out;
	err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
	if (err)
		goto out;
	init_chdir("/.."); /* will traverse into overmounted root */
	init_chroot(".");
out:
	*(int *)p = err;
	complete(&setup_done);
	return err;
}

/*
 * The __ref is because devtmpfs_setup needs to be __init for the routines it
 * calls.  That call is done while devtmpfs_init, which is marked __init,
 * synchronously waits for it to complete.
 */
static int __ref devtmpfsd(void *p)
{
	int err = devtmpfs_setup(p);

	if (err)
		return err;
	devtmpfs_work_loop();
	return 0;
}

/*
 * 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>
c60166f0	28	#include <linux/init_syscalls.h>
e262e32d	29	#include <uapi/linux/mount.h>
c3a30420	30	#include "base.h"
2b2af54a	31
2780f1ff	32	static struct task_struct *thread;
2b2af54a	33
fad1db8a	34	static int __initdata mount_dev = IS_ENABLED(CONFIG_DEVTMPFS_MOUNT);
2b2af54a	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 */
4e4098a3 GKH	44	kuid_t uid;
4e4098a3 GKH	45	kgid_t gid;
2780f1ff AV	46	struct device *dev;
2780f1ff AV	47	} *requests;
ed413ae6	48
2b2af54a KS	49	static int __init mount_param(char *str)
2b2af54a KS	50	{
fc14f2fe	51	mount_dev = simple_strtoul(str, NULL, 0);
2b2af54a KS	52	return 1;
	53	}
	54	__setup("devtmpfs.mount=", mount_param);
	55
d401727e AV	56	static struct vfsmount *mnt;
	57
	58	static struct dentry public_dev_mount(struct file_system_type fs_type, int flags,
	59	const char dev_name, void data)
	60	{
	61	struct super_block *s = mnt->mnt_sb;
	62	atomic_inc(&s->s_active);
	63	down_write(&s->s_umount);
	64	return dget(s->s_root);
	65	}
	66
f3235626 DH	67	static struct file_system_type internal_fs_type = {
f3235626 DH	68	.name = "devtmpfs",
da5e4ef7	69	#ifdef CONFIG_TMPFS
f3235626	70	.init_fs_context = shmem_init_fs_context,
d7167b14	71	.parameters = shmem_fs_parameters,
da5e4ef7	72	#else
f3235626	73	.init_fs_context = ramfs_init_fs_context,
d7167b14	74	.parameters = ramfs_fs_parameters,
da5e4ef7	75	#endif
2b2af54a KS	76	.kill_sb = kill_litter_super,
	77	};
	78
d401727e AV	79	static struct file_system_type dev_fs_type = {
	80	.name = "devtmpfs",
	81	.mount = public_dev_mount,
	82	};
	83
2b2af54a KS	84	#ifdef CONFIG_BLOCK
	85	static inline int is_blockdev(struct device *dev)
	86	{
	87	return dev->class == &block_class;
	88	}
	89	#else
	90	static inline int is_blockdev(struct device *dev) { return 0; }
	91	#endif
	92
72a9cc95 RV	93	static int devtmpfs_submit_req(struct req req, const char tmp)
	94	{
	95	init_completion(&req->done);
	96
	97	spin_lock(&req_lock);
	98	req->next = requests;
	99	requests = req;
	100	spin_unlock(&req_lock);
	101
	102	wake_up_process(thread);
	103	wait_for_completion(&req->done);
	104
	105	kfree(tmp);
	106
	107	return req->err;
	108	}
	109
2780f1ff AV	110	int devtmpfs_create_node(struct device *dev)
	111	{
	112	const char *tmp = NULL;
	113	struct req req;
	114
	115	if (!thread)
	116	return 0;
	117
	118	req.mode = 0;
4e4098a3 GKH	119	req.uid = GLOBAL_ROOT_UID;
4e4098a3 GKH	120	req.gid = GLOBAL_ROOT_GID;
3c2670e6	121	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
2780f1ff AV	122	if (!req.name)
	123	return -ENOMEM;
	124
	125	if (req.mode == 0)
	126	req.mode = 0600;
	127	if (is_blockdev(dev))
	128	req.mode \|= S_IFBLK;
	129	else
	130	req.mode \|= S_IFCHR;
	131
	132	req.dev = dev;
	133
72a9cc95	134	return devtmpfs_submit_req(&req, tmp);
2780f1ff AV	135	}
	136
	137	int devtmpfs_delete_node(struct device *dev)
	138	{
	139	const char *tmp = NULL;
	140	struct req req;
	141
	142	if (!thread)
	143	return 0;
	144
3c2670e6	145	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
2780f1ff AV	146	if (!req.name)
	147	return -ENOMEM;
	148
	149	req.mode = 0;
	150	req.dev = dev;
	151
72a9cc95	152	return devtmpfs_submit_req(&req, tmp);
2780f1ff AV	153	}
2780f1ff AV	154
fbd48a69	155	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	156	{
2b2af54a	157	struct dentry *dentry;
69753a0f	158	struct path path;
2b2af54a KS	159	int err;
2b2af54a KS	160
1ac12b4b	161	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
69753a0f AV	162	if (IS_ERR(dentry))
	163	return PTR_ERR(dentry);
	164
75c3cfa8	165	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
69753a0f AV	166	if (!err)
69753a0f AV	167	/* mark as kernel-created inode */
75c3cfa8	168	d_inode(dentry)->i_private = &thread;
921a1650	169	done_path_create(&path, dentry);
2b2af54a KS	170	return err;
	171	}
	172
	173	static int create_path(const char *nodepath)
	174	{
5da4e689 AV	175	char *path;
5da4e689 AV	176	char *s;
9d108d25	177	int err = 0;
2b2af54a	178
5da4e689 AV	179	/* parent directories do not exist, create them */
	180	path = kstrdup(nodepath, GFP_KERNEL);
	181	if (!path)
	182	return -ENOMEM;
	183
	184	s = path;
	185	for (;;) {
	186	s = strchr(s, '/');
	187	if (!s)
	188	break;
	189	s[0] = '\0';
	190	err = dev_mkdir(path, 0755);
	191	if (err && err != -EEXIST)
	192	break;
	193	s[0] = '/';
	194	s++;
2b2af54a	195	}
5da4e689	196	kfree(path);
2b2af54a KS	197	return err;
	198	}
	199
4e4098a3 GKH	200	static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
4e4098a3 GKH	201	kgid_t gid, struct device *dev)
2b2af54a	202	{
2b2af54a	203	struct dentry *dentry;
69753a0f	204	struct path path;
2b2af54a KS	205	int err;
2b2af54a KS	206
69753a0f AV	207	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	208	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	209	create_path(nodename);
69753a0f	210	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	211	}
69753a0f AV	212	if (IS_ERR(dentry))
	213	return PTR_ERR(dentry);
	214
75c3cfa8	215	err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
69753a0f AV	216	if (!err) {
	217	struct iattr newattrs;
	218
69753a0f	219	newattrs.ia_mode = mode;
4e4098a3 GKH	220	newattrs.ia_uid = uid;
4e4098a3 GKH	221	newattrs.ia_gid = gid;
3c2670e6	222	newattrs.ia_valid = ATTR_MODE\|ATTR_UID\|ATTR_GID;
5955102c	223	inode_lock(d_inode(dentry));
2f221d6f	224	notify_change(&init_user_ns, dentry, &newattrs, NULL);
5955102c	225	inode_unlock(d_inode(dentry));
69753a0f AV	226
69753a0f AV	227	/* mark as kernel-created inode */
75c3cfa8	228	d_inode(dentry)->i_private = &thread;
2b2af54a	229	}
921a1650	230	done_path_create(&path, dentry);
2b2af54a KS	231	return err;
	232	}
	233
	234	static int dev_rmdir(const char *name)
	235	{
79714f72	236	struct path parent;
2b2af54a KS	237	struct dentry *dentry;
	238	int err;
	239
79714f72 AV	240	dentry = kern_path_locked(name, &parent);
	241	if (IS_ERR(dentry))
	242	return PTR_ERR(dentry);
75c3cfa8 DH	243	if (d_really_is_positive(dentry)) {
	244	if (d_inode(dentry)->i_private == &thread)
	245	err = vfs_rmdir(d_inode(parent.dentry), dentry);
79714f72 AV	246	else
79714f72 AV	247	err = -EPERM;
2b2af54a	248	} else {
79714f72	249	err = -ENOENT;
2b2af54a	250	}
79714f72	251	dput(dentry);
5955102c	252	inode_unlock(d_inode(parent.dentry));
79714f72	253	path_put(&parent);
2b2af54a KS	254	return err;
	255	}
	256
	257	static int delete_path(const char *nodepath)
	258	{
be6b1dfe	259	char *path;
2b2af54a KS	260	int err = 0;
	261
	262	path = kstrdup(nodepath, GFP_KERNEL);
	263	if (!path)
	264	return -ENOMEM;
	265
ed413ae6	266	for (;;) {
2b2af54a KS	267	char *base;
	268
	269	base = strrchr(path, '/');
	270	if (!base)
	271	break;
	272	base[0] = '\0';
	273	err = dev_rmdir(path);
	274	if (err)
	275	break;
	276	}
	277
	278	kfree(path);
	279	return err;
	280	}
	281
	282	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	283	{
	284	/* did we create it */
2780f1ff	285	if (inode->i_private != &thread)
2b2af54a KS	286	return 0;
	287
	288	/* does the dev_t match */
	289	if (is_blockdev(dev)) {
	290	if (!S_ISBLK(stat->mode))
	291	return 0;
	292	} else {
	293	if (!S_ISCHR(stat->mode))
	294	return 0;
	295	}
	296	if (stat->rdev != dev->devt)
	297	return 0;
	298
	299	/* ours */
	300	return 1;
	301	}
	302
2780f1ff	303	static int handle_remove(const char nodename, struct device dev)
2b2af54a	304	{
79714f72	305	struct path parent;
2b2af54a	306	struct dentry *dentry;
fbde7c61	307	int deleted = 0;
2b2af54a KS	308	int err;
2b2af54a KS	309
79714f72 AV	310	dentry = kern_path_locked(nodename, &parent);
	311	if (IS_ERR(dentry))
	312	return PTR_ERR(dentry);
	313
75c3cfa8	314	if (d_really_is_positive(dentry)) {
79714f72	315	struct kstat stat;
3dadecce	316	struct path p = {.mnt = parent.mnt, .dentry = dentry};
a528d35e DH	317	err = vfs_getattr(&p, &stat, STATX_TYPE \| STATX_MODE,
a528d35e DH	318	AT_STATX_SYNC_AS_STAT);
75c3cfa8	319	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
79714f72 AV	320	struct iattr newattrs;
	321	/*
	322	* before unlinking this node, reset permissions
	323	* of possible references like hardlinks
	324	*/
91fa2cca EB	325	newattrs.ia_uid = GLOBAL_ROOT_UID;
91fa2cca EB	326	newattrs.ia_gid = GLOBAL_ROOT_GID;
79714f72 AV	327	newattrs.ia_mode = stat.mode & ~0777;
	328	newattrs.ia_valid =
	329	ATTR_UID\|ATTR_GID\|ATTR_MODE;
5955102c	330	inode_lock(d_inode(dentry));
2f221d6f	331	notify_change(&init_user_ns, dentry, &newattrs, NULL);
5955102c	332	inode_unlock(d_inode(dentry));
75c3cfa8	333	err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
79714f72 AV	334	if (!err \|\| err == -ENOENT)
79714f72 AV	335	deleted = 1;
2b2af54a	336	}
2b2af54a	337	} else {
79714f72	338	err = -ENOENT;
2b2af54a	339	}
79714f72	340	dput(dentry);
5955102c	341	inode_unlock(d_inode(parent.dentry));
2b2af54a	342
79714f72	343	path_put(&parent);
2b2af54a KS	344	if (deleted && strchr(nodename, '/'))
2b2af54a KS	345	delete_path(nodename);
2b2af54a KS	346	return err;
	347	}
	348
	349	/*
	350	* If configured, or requested by the commandline, devtmpfs will be
	351	* auto-mounted after the kernel mounted the root filesystem.
	352	*/
fad1db8a	353	int __init devtmpfs_mount(void)
2b2af54a	354	{
2b2af54a KS	355	int err;
2b2af54a KS	356
fc14f2fe	357	if (!mount_dev)
2b2af54a KS	358	return 0;
2b2af54a KS	359
2780f1ff	360	if (!thread)
2b2af54a KS	361	return 0;
2b2af54a KS	362
c60166f0	363	err = init_mount("devtmpfs", "dev", "devtmpfs", MS_SILENT, NULL);
2b2af54a KS	364	if (err)
	365	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	366	else
	367	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	368	return err;
	369	}
	370
f9e0b159	371	static DECLARE_COMPLETION(setup_done);
2780f1ff	372
4e4098a3	373	static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
3c2670e6	374	struct device *dev)
2780f1ff AV	375	{
2780f1ff AV	376	if (mode)
3c2670e6	377	return handle_create(name, mode, uid, gid, dev);
2780f1ff AV	378	else
	379	return handle_remove(name, dev);
	380	}
	381
bcbacc49 CH	382	static void __noreturn devtmpfs_work_loop(void)
	383	{
	384	while (1) {
	385	spin_lock(&req_lock);
	386	while (requests) {
	387	struct req *req = requests;
	388	requests = NULL;
	389	spin_unlock(&req_lock);
	390	while (req) {
	391	struct req *next = req->next;
	392	req->err = handle(req->name, req->mode,
	393	req->uid, req->gid, req->dev);
	394	complete(&req->done);
	395	req = next;
	396	}
	397	spin_lock(&req_lock);
	398	}
	399	__set_current_state(TASK_INTERRUPTIBLE);
	400	spin_unlock(&req_lock);
	401	schedule();
	402	}
	403	}
	404
	405	static int __init devtmpfs_setup(void *p)
2780f1ff	406	{
c9d6b287 RV	407	int err;
	408
	409	err = ksys_unshare(CLONE_NEWNS);
	410	if (err)
2780f1ff	411	goto out;
c60166f0	412	err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
c9d6b287	413	if (err)
2780f1ff	414	goto out;
db63f1e3	415	init_chdir("/.."); /* will traverse into overmounted root */
4b7ca501	416	init_chroot(".");
0ff0e95e RV	417	out:
0ff0e95e RV	418	(int )p = err;
2780f1ff	419	complete(&setup_done);
0ff0e95e RV	420	return err;
	421	}
	422
bcbacc49 CH	423	/*
	424	* The __ref is because devtmpfs_setup needs to be __init for the routines it
	425	* calls. That call is done while devtmpfs_init, which is marked __init,
	426	* synchronously waits for it to complete.
	427	*/
	428	static int __ref devtmpfsd(void *p)
0ff0e95e RV	429	{
	430	int err = devtmpfs_setup(p);
	431
	432	if (err)
	433	return err;
bcbacc49	434	devtmpfs_work_loop();
2780f1ff	435	return 0;
2780f1ff AV	436	}
2780f1ff AV	437
2b2af54a KS	438	/*
	439	* Create devtmpfs instance, driver-core devices will add their device
	440	* nodes here.
	441	*/
	442	int __init devtmpfs_init(void)
	443	{
d401727e AV	444	char opts[] = "mode=0755";
	445	int err;
	446
	447	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	448	if (IS_ERR(mnt)) {
	449	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
	450	PTR_ERR(mnt));
	451	return PTR_ERR(mnt);
	452	}
	453	err = register_filesystem(&dev_fs_type);
2b2af54a KS	454	if (err) {
	455	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	456	"type %i\n", err);
	457	return err;
	458	}
	459
2780f1ff AV	460	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	461	if (!IS_ERR(thread)) {
	462	wait_for_completion(&setup_done);
	463	} else {
	464	err = PTR_ERR(thread);
	465	thread = NULL;
	466	}
	467
	468	if (err) {
2b2af54a KS	469	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	470	unregister_filesystem(&dev_fs_type);
	471	return err;
	472	}
2b2af54a KS	473
	474	printk(KERN_INFO "devtmpfs: initialized\n");
	475	return 0;
	476	}