[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 dentry *dev_mount(struct file_system_type *fs_type, int flags,
		      const char *dev_name, void *data)
{
#ifdef CONFIG_TMPFS
	return shmem_mount(fs_type, flags, dev_name, data);
#else
	return ramfs_mount(fs_type, flags, dev_name, data);
#endif
}

static struct file_system_type internal_fs_type = {
	.name = "devtmpfs",
	.mount = dev_mount,
	.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
fc14f2fe AV	70	static struct dentry dev_mount(struct file_system_type fs_type, int flags,
fc14f2fe AV	71	const char dev_name, void data)
2b2af54a	72	{
da5e4ef7	73	#ifdef CONFIG_TMPFS
7e30d2a5	74	return shmem_mount(fs_type, flags, dev_name, data);
da5e4ef7	75	#else
d401727e	76	return ramfs_mount(fs_type, flags, dev_name, data);
da5e4ef7	77	#endif
2b2af54a KS	78	}
2b2af54a KS	79
d401727e	80	static struct file_system_type internal_fs_type = {
2b2af54a	81	.name = "devtmpfs",
fc14f2fe	82	.mount = dev_mount,
2b2af54a KS	83	.kill_sb = kill_litter_super,
	84	};
	85
d401727e AV	86	static struct file_system_type dev_fs_type = {
	87	.name = "devtmpfs",
	88	.mount = public_dev_mount,
	89	};
	90
2b2af54a KS	91	#ifdef CONFIG_BLOCK
	92	static inline int is_blockdev(struct device *dev)
	93	{
	94	return dev->class == &block_class;
	95	}
	96	#else
	97	static inline int is_blockdev(struct device *dev) { return 0; }
	98	#endif
	99
2780f1ff AV	100	int devtmpfs_create_node(struct device *dev)
	101	{
	102	const char *tmp = NULL;
	103	struct req req;
	104
	105	if (!thread)
	106	return 0;
	107
	108	req.mode = 0;
4e4098a3 GKH	109	req.uid = GLOBAL_ROOT_UID;
4e4098a3 GKH	110	req.gid = GLOBAL_ROOT_GID;
3c2670e6	111	req.name = device_get_devnode(dev, &req.mode, &req.uid, &req.gid, &tmp);
2780f1ff AV	112	if (!req.name)
	113	return -ENOMEM;
	114
	115	if (req.mode == 0)
	116	req.mode = 0600;
	117	if (is_blockdev(dev))
	118	req.mode \|= S_IFBLK;
	119	else
	120	req.mode \|= S_IFCHR;
	121
	122	req.dev = dev;
	123
	124	init_completion(&req.done);
	125
	126	spin_lock(&req_lock);
	127	req.next = requests;
	128	requests = &req;
	129	spin_unlock(&req_lock);
	130
	131	wake_up_process(thread);
	132	wait_for_completion(&req.done);
	133
	134	kfree(tmp);
	135
	136	return req.err;
	137	}
	138
	139	int devtmpfs_delete_node(struct device *dev)
	140	{
	141	const char *tmp = NULL;
	142	struct req req;
	143
	144	if (!thread)
	145	return 0;
	146
3c2670e6	147	req.name = device_get_devnode(dev, NULL, NULL, NULL, &tmp);
2780f1ff AV	148	if (!req.name)
	149	return -ENOMEM;
	150
	151	req.mode = 0;
	152	req.dev = dev;
	153
	154	init_completion(&req.done);
	155
	156	spin_lock(&req_lock);
	157	req.next = requests;
	158	requests = &req;
	159	spin_unlock(&req_lock);
	160
	161	wake_up_process(thread);
	162	wait_for_completion(&req.done);
	163
	164	kfree(tmp);
	165	return req.err;
	166	}
	167
fbd48a69	168	static int dev_mkdir(const char *name, umode_t mode)
2b2af54a	169	{
2b2af54a	170	struct dentry *dentry;
69753a0f	171	struct path path;
2b2af54a KS	172	int err;
2b2af54a KS	173
1ac12b4b	174	dentry = kern_path_create(AT_FDCWD, name, &path, LOOKUP_DIRECTORY);
69753a0f AV	175	if (IS_ERR(dentry))
	176	return PTR_ERR(dentry);
	177
75c3cfa8	178	err = vfs_mkdir(d_inode(path.dentry), dentry, mode);
69753a0f AV	179	if (!err)
69753a0f AV	180	/* mark as kernel-created inode */
75c3cfa8	181	d_inode(dentry)->i_private = &thread;
921a1650	182	done_path_create(&path, dentry);
2b2af54a KS	183	return err;
	184	}
	185
	186	static int create_path(const char *nodepath)
	187	{
5da4e689 AV	188	char *path;
5da4e689 AV	189	char *s;
9d108d25	190	int err = 0;
2b2af54a	191
5da4e689 AV	192	/* parent directories do not exist, create them */
	193	path = kstrdup(nodepath, GFP_KERNEL);
	194	if (!path)
	195	return -ENOMEM;
	196
	197	s = path;
	198	for (;;) {
	199	s = strchr(s, '/');
	200	if (!s)
	201	break;
	202	s[0] = '\0';
	203	err = dev_mkdir(path, 0755);
	204	if (err && err != -EEXIST)
	205	break;
	206	s[0] = '/';
	207	s++;
2b2af54a	208	}
5da4e689	209	kfree(path);
2b2af54a KS	210	return err;
	211	}
	212
4e4098a3 GKH	213	static int handle_create(const char *nodename, umode_t mode, kuid_t uid,
4e4098a3 GKH	214	kgid_t gid, struct device *dev)
2b2af54a	215	{
2b2af54a	216	struct dentry *dentry;
69753a0f	217	struct path path;
2b2af54a KS	218	int err;
2b2af54a KS	219
69753a0f AV	220	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
69753a0f AV	221	if (dentry == ERR_PTR(-ENOENT)) {
2b2af54a	222	create_path(nodename);
69753a0f	223	dentry = kern_path_create(AT_FDCWD, nodename, &path, 0);
2b2af54a	224	}
69753a0f AV	225	if (IS_ERR(dentry))
	226	return PTR_ERR(dentry);
	227
75c3cfa8	228	err = vfs_mknod(d_inode(path.dentry), dentry, mode, dev->devt);
69753a0f AV	229	if (!err) {
	230	struct iattr newattrs;
	231
69753a0f	232	newattrs.ia_mode = mode;
4e4098a3 GKH	233	newattrs.ia_uid = uid;
4e4098a3 GKH	234	newattrs.ia_gid = gid;
3c2670e6	235	newattrs.ia_valid = ATTR_MODE\|ATTR_UID\|ATTR_GID;
5955102c	236	inode_lock(d_inode(dentry));
27ac0ffe	237	notify_change(dentry, &newattrs, NULL);
5955102c	238	inode_unlock(d_inode(dentry));
69753a0f AV	239
69753a0f AV	240	/* mark as kernel-created inode */
75c3cfa8	241	d_inode(dentry)->i_private = &thread;
2b2af54a	242	}
921a1650	243	done_path_create(&path, dentry);
2b2af54a KS	244	return err;
	245	}
	246
	247	static int dev_rmdir(const char *name)
	248	{
79714f72	249	struct path parent;
2b2af54a KS	250	struct dentry *dentry;
	251	int err;
	252
79714f72 AV	253	dentry = kern_path_locked(name, &parent);
	254	if (IS_ERR(dentry))
	255	return PTR_ERR(dentry);
75c3cfa8 DH	256	if (d_really_is_positive(dentry)) {
	257	if (d_inode(dentry)->i_private == &thread)
	258	err = vfs_rmdir(d_inode(parent.dentry), dentry);
79714f72 AV	259	else
79714f72 AV	260	err = -EPERM;
2b2af54a	261	} else {
79714f72	262	err = -ENOENT;
2b2af54a	263	}
79714f72	264	dput(dentry);
5955102c	265	inode_unlock(d_inode(parent.dentry));
79714f72	266	path_put(&parent);
2b2af54a KS	267	return err;
	268	}
	269
	270	static int delete_path(const char *nodepath)
	271	{
be6b1dfe	272	char *path;
2b2af54a KS	273	int err = 0;
	274
	275	path = kstrdup(nodepath, GFP_KERNEL);
	276	if (!path)
	277	return -ENOMEM;
	278
ed413ae6	279	for (;;) {
2b2af54a KS	280	char *base;
	281
	282	base = strrchr(path, '/');
	283	if (!base)
	284	break;
	285	base[0] = '\0';
	286	err = dev_rmdir(path);
	287	if (err)
	288	break;
	289	}
	290
	291	kfree(path);
	292	return err;
	293	}
	294
	295	static int dev_mynode(struct device dev, struct inode inode, struct kstat *stat)
	296	{
	297	/* did we create it */
2780f1ff	298	if (inode->i_private != &thread)
2b2af54a KS	299	return 0;
	300
	301	/* does the dev_t match */
	302	if (is_blockdev(dev)) {
	303	if (!S_ISBLK(stat->mode))
	304	return 0;
	305	} else {
	306	if (!S_ISCHR(stat->mode))
	307	return 0;
	308	}
	309	if (stat->rdev != dev->devt)
	310	return 0;
	311
	312	/* ours */
	313	return 1;
	314	}
	315
2780f1ff	316	static int handle_remove(const char nodename, struct device dev)
2b2af54a	317	{
79714f72	318	struct path parent;
2b2af54a	319	struct dentry *dentry;
fbde7c61	320	int deleted = 0;
2b2af54a KS	321	int err;
2b2af54a KS	322
79714f72 AV	323	dentry = kern_path_locked(nodename, &parent);
	324	if (IS_ERR(dentry))
	325	return PTR_ERR(dentry);
	326
75c3cfa8	327	if (d_really_is_positive(dentry)) {
79714f72	328	struct kstat stat;
3dadecce	329	struct path p = {.mnt = parent.mnt, .dentry = dentry};
a528d35e DH	330	err = vfs_getattr(&p, &stat, STATX_TYPE \| STATX_MODE,
a528d35e DH	331	AT_STATX_SYNC_AS_STAT);
75c3cfa8	332	if (!err && dev_mynode(dev, d_inode(dentry), &stat)) {
79714f72 AV	333	struct iattr newattrs;
	334	/*
	335	* before unlinking this node, reset permissions
	336	* of possible references like hardlinks
	337	*/
91fa2cca EB	338	newattrs.ia_uid = GLOBAL_ROOT_UID;
91fa2cca EB	339	newattrs.ia_gid = GLOBAL_ROOT_GID;
79714f72 AV	340	newattrs.ia_mode = stat.mode & ~0777;
	341	newattrs.ia_valid =
	342	ATTR_UID\|ATTR_GID\|ATTR_MODE;
5955102c	343	inode_lock(d_inode(dentry));
27ac0ffe	344	notify_change(dentry, &newattrs, NULL);
5955102c	345	inode_unlock(d_inode(dentry));
75c3cfa8	346	err = vfs_unlink(d_inode(parent.dentry), dentry, NULL);
79714f72 AV	347	if (!err \|\| err == -ENOENT)
79714f72 AV	348	deleted = 1;
2b2af54a	349	}
2b2af54a	350	} else {
79714f72	351	err = -ENOENT;
2b2af54a	352	}
79714f72	353	dput(dentry);
5955102c	354	inode_unlock(d_inode(parent.dentry));
2b2af54a	355
79714f72	356	path_put(&parent);
2b2af54a KS	357	if (deleted && strchr(nodename, '/'))
2b2af54a KS	358	delete_path(nodename);
2b2af54a KS	359	return err;
	360	}
	361
	362	/*
	363	* If configured, or requested by the commandline, devtmpfs will be
	364	* auto-mounted after the kernel mounted the root filesystem.
	365	*/
073120cc	366	int devtmpfs_mount(const char *mntdir)
2b2af54a	367	{
2b2af54a KS	368	int err;
2b2af54a KS	369
fc14f2fe	370	if (!mount_dev)
2b2af54a KS	371	return 0;
2b2af54a KS	372
2780f1ff	373	if (!thread)
2b2af54a KS	374	return 0;
2b2af54a KS	375
33488845	376	err = ksys_mount("devtmpfs", mntdir, "devtmpfs", MS_SILENT, NULL);
2b2af54a KS	377	if (err)
	378	printk(KERN_INFO "devtmpfs: error mounting %i\n", err);
	379	else
	380	printk(KERN_INFO "devtmpfs: mounted\n");
2b2af54a KS	381	return err;
	382	}
	383
f9e0b159	384	static DECLARE_COMPLETION(setup_done);
2780f1ff	385
4e4098a3	386	static int handle(const char *name, umode_t mode, kuid_t uid, kgid_t gid,
3c2670e6	387	struct device *dev)
2780f1ff AV	388	{
2780f1ff AV	389	if (mode)
3c2670e6	390	return handle_create(name, mode, uid, gid, dev);
2780f1ff AV	391	else
	392	return handle_remove(name, dev);
	393	}
	394
	395	static int devtmpfsd(void *p)
	396	{
2780f1ff	397	int *err = p;
9b32105e	398	*err = ksys_unshare(CLONE_NEWNS);
2780f1ff AV	399	if (*err)
2780f1ff AV	400	goto out;
d401727e	401	*err = ksys_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL);
2780f1ff AV	402	if (*err)
2780f1ff AV	403	goto out;
447016e9	404	ksys_chdir("/.."); /* will traverse into overmounted root */
a16fe33a	405	ksys_chroot(".");
2780f1ff AV	406	complete(&setup_done);
	407	while (1) {
	408	spin_lock(&req_lock);
	409	while (requests) {
	410	struct req *req = requests;
	411	requests = NULL;
	412	spin_unlock(&req_lock);
	413	while (req) {
e13889ba	414	struct req *next = req->next;
3c2670e6 KS	415	req->err = handle(req->name, req->mode,
3c2670e6 KS	416	req->uid, req->gid, req->dev);
2780f1ff	417	complete(&req->done);
e13889ba	418	req = next;
2780f1ff AV	419	}
	420	spin_lock(&req_lock);
	421	}
65e6757b	422	__set_current_state(TASK_INTERRUPTIBLE);
2780f1ff AV	423	spin_unlock(&req_lock);
2780f1ff AV	424	schedule();
2780f1ff AV	425	}
	426	return 0;
	427	out:
	428	complete(&setup_done);
	429	return *err;
	430	}
	431
2b2af54a KS	432	/*
	433	* Create devtmpfs instance, driver-core devices will add their device
	434	* nodes here.
	435	*/
	436	int __init devtmpfs_init(void)
	437	{
d401727e AV	438	char opts[] = "mode=0755";
	439	int err;
	440
	441	mnt = vfs_kern_mount(&internal_fs_type, 0, "devtmpfs", opts);
	442	if (IS_ERR(mnt)) {
	443	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %ld\n",
	444	PTR_ERR(mnt));
	445	return PTR_ERR(mnt);
	446	}
	447	err = register_filesystem(&dev_fs_type);
2b2af54a KS	448	if (err) {
	449	printk(KERN_ERR "devtmpfs: unable to register devtmpfs "
	450	"type %i\n", err);
	451	return err;
	452	}
	453
2780f1ff AV	454	thread = kthread_run(devtmpfsd, &err, "kdevtmpfs");
	455	if (!IS_ERR(thread)) {
	456	wait_for_completion(&setup_done);
	457	} else {
	458	err = PTR_ERR(thread);
	459	thread = NULL;
	460	}
	461
	462	if (err) {
2b2af54a KS	463	printk(KERN_ERR "devtmpfs: unable to create devtmpfs %i\n", err);
	464	unregister_filesystem(&dev_fs_type);
	465	return err;
	466	}
2b2af54a KS	467
	468	printk(KERN_INFO "devtmpfs: initialized\n");
	469	return 0;
	470	}