[linux.git] / fs / sysfs / inode.c

/*
 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <[email protected]>
 *
 * This file is released under the GPLv2.
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#undef DEBUG 

#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/backing-dev.h>
#include <linux/capability.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/sysfs.h>
#include <linux/xattr.h>
#include <linux/security.h>
#include "sysfs.h"

extern struct super_block * sysfs_sb;

static const struct address_space_operations sysfs_aops = {
	.readpage	= simple_readpage,
	.write_begin	= simple_write_begin,
	.write_end	= simple_write_end,
};

static struct backing_dev_info sysfs_backing_dev_info = {
	.name		= "sysfs",
	.ra_pages	= 0,	/* No readahead */
	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
};

static const struct inode_operations sysfs_inode_operations ={
	.permission	= sysfs_permission,
	.setattr	= sysfs_setattr,
	.getattr	= sysfs_getattr,
	.setxattr	= sysfs_setxattr,
};

int __init sysfs_inode_init(void)
{
	return bdi_init(&sysfs_backing_dev_info);
}

static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
{
	struct sysfs_inode_attrs *attrs;
	struct iattr *iattrs;

	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	if (!attrs)
		return NULL;
	iattrs = &attrs->ia_iattr;

	/* assign default attributes */
	iattrs->ia_mode = sd->s_mode;
	iattrs->ia_uid = 0;
	iattrs->ia_gid = 0;
	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;

	return attrs;
}

int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
{
	struct sysfs_inode_attrs *sd_attrs;
	struct iattr *iattrs;
	unsigned int ia_valid = iattr->ia_valid;

	sd_attrs = sd->s_iattr;

	if (!sd_attrs) {
		/* setting attributes for the first time, allocate now */
		sd_attrs = sysfs_init_inode_attrs(sd);
		if (!sd_attrs)
			return -ENOMEM;
		sd->s_iattr = sd_attrs;
	}
	/* attributes were changed at least once in past */
	iattrs = &sd_attrs->ia_iattr;

	if (ia_valid & ATTR_UID)
		iattrs->ia_uid = iattr->ia_uid;
	if (ia_valid & ATTR_GID)
		iattrs->ia_gid = iattr->ia_gid;
	if (ia_valid & ATTR_ATIME)
		iattrs->ia_atime = iattr->ia_atime;
	if (ia_valid & ATTR_MTIME)
		iattrs->ia_mtime = iattr->ia_mtime;
	if (ia_valid & ATTR_CTIME)
		iattrs->ia_ctime = iattr->ia_ctime;
	if (ia_valid & ATTR_MODE) {
		umode_t mode = iattr->ia_mode;
		iattrs->ia_mode = sd->s_mode = mode;
	}
	return 0;
}

int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
{
	struct inode *inode = dentry->d_inode;
	struct sysfs_dirent *sd = dentry->d_fsdata;
	int error;

	if (!sd)
		return -EINVAL;

	mutex_lock(&sysfs_mutex);
	error = inode_change_ok(inode, iattr);
	if (error)
		goto out;

	error = sysfs_sd_setattr(sd, iattr);
	if (error)
		goto out;

	/* this ignores size changes */
	setattr_copy(inode, iattr);

out:
	mutex_unlock(&sysfs_mutex);
	return error;
}

static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
{
	struct sysfs_inode_attrs *iattrs;
	void *old_secdata;
	size_t old_secdata_len;

	iattrs = sd->s_iattr;
	if (!iattrs)
		iattrs = sysfs_init_inode_attrs(sd);
	if (!iattrs)
		return -ENOMEM;

	old_secdata = iattrs->ia_secdata;
	old_secdata_len = iattrs->ia_secdata_len;

	iattrs->ia_secdata = *secdata;
	iattrs->ia_secdata_len = *secdata_len;

	*secdata = old_secdata;
	*secdata_len = old_secdata_len;
	return 0;
}

int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
		size_t size, int flags)
{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	void *secdata;
	int error;
	u32 secdata_len = 0;

	if (!sd)
		return -EINVAL;

	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
		const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
		error = security_inode_setsecurity(dentry->d_inode, suffix,
						value, size, flags);
		if (error)
			goto out;
		error = security_inode_getsecctx(dentry->d_inode,
						&secdata, &secdata_len);
		if (error)
			goto out;

		mutex_lock(&sysfs_mutex);
		error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
		mutex_unlock(&sysfs_mutex);

		if (secdata)
			security_release_secctx(secdata, secdata_len);
	} else
		return -EINVAL;
out:
	return error;
}

static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
{
	inode->i_mode = mode;
	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}

static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
{
	inode->i_uid = iattr->ia_uid;
	inode->i_gid = iattr->ia_gid;
	inode->i_atime = iattr->ia_atime;
	inode->i_mtime = iattr->ia_mtime;
	inode->i_ctime = iattr->ia_ctime;
}

static int sysfs_count_nlink(struct sysfs_dirent *sd)
{
	struct sysfs_dirent *child;
	int nr = 0;

	for (child = sd->s_dir.children; child; child = child->s_sibling)
		if (sysfs_type(child) == SYSFS_DIR)
			nr++;

	return nr + 2;
}

static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
{
	struct sysfs_inode_attrs *iattrs = sd->s_iattr;

	inode->i_mode = sd->s_mode;
	if (iattrs) {
		/* sysfs_dirent has non-default attributes
		 * get them from persistent copy in sysfs_dirent
		 */
		set_inode_attr(inode, &iattrs->ia_iattr);
		security_inode_notifysecctx(inode,
					    iattrs->ia_secdata,
					    iattrs->ia_secdata_len);
	}

	if (sysfs_type(sd) == SYSFS_DIR)
		inode->i_nlink = sysfs_count_nlink(sd);
}

int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
	struct sysfs_dirent *sd = dentry->d_fsdata;
	struct inode *inode = dentry->d_inode;

	mutex_lock(&sysfs_mutex);
	sysfs_refresh_inode(sd, inode);
	mutex_unlock(&sysfs_mutex);

	generic_fillattr(inode, stat);
	return 0;
}

static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
{
	struct bin_attribute *bin_attr;

	inode->i_private = sysfs_get(sd);
	inode->i_mapping->a_ops = &sysfs_aops;
	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	inode->i_op = &sysfs_inode_operations;

	set_default_inode_attr(inode, sd->s_mode);
	sysfs_refresh_inode(sd, inode);

	/* initialize inode according to type */
	switch (sysfs_type(sd)) {
	case SYSFS_DIR:
		inode->i_op = &sysfs_dir_inode_operations;
		inode->i_fop = &sysfs_dir_operations;
		break;
	case SYSFS_KOBJ_ATTR:
		inode->i_size = PAGE_SIZE;
		inode->i_fop = &sysfs_file_operations;
		break;
	case SYSFS_KOBJ_BIN_ATTR:
		bin_attr = sd->s_bin_attr.bin_attr;
		inode->i_size = bin_attr->size;
		inode->i_fop = &bin_fops;
		break;
	case SYSFS_KOBJ_LINK:
		inode->i_op = &sysfs_symlink_inode_operations;
		break;
	default:
		BUG();
	}

	unlock_new_inode(inode);
}

/**
 *	sysfs_get_inode - get inode for sysfs_dirent
 *	@sb: super block
 *	@sd: sysfs_dirent to allocate inode for
 *
 *	Get inode for @sd.  If such inode doesn't exist, a new inode
 *	is allocated and basics are initialized.  New inode is
 *	returned locked.
 *
 *	LOCKING:
 *	Kernel thread context (may sleep).
 *
 *	RETURNS:
 *	Pointer to allocated inode on success, NULL on failure.
 */
struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
{
	struct inode *inode;

	inode = iget_locked(sb, sd->s_ino);
	if (inode && (inode->i_state & I_NEW))
		sysfs_init_inode(sd, inode);

	return inode;
}

/*
 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
 * To prevent the sysfs inode numbers from being freed prematurely we take a
 * reference to sysfs_dirent from the sysfs inode.  A
 * super_operations.evict_inode() implementation is needed to drop that
 * reference upon inode destruction.
 */
void sysfs_evict_inode(struct inode *inode)
{
	struct sysfs_dirent *sd  = inode->i_private;

	truncate_inode_pages(&inode->i_data, 0);
	end_writeback(inode);
	sysfs_put(sd);
}

int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const char *name)
{
	struct sysfs_addrm_cxt acxt;
	struct sysfs_dirent *sd;

	if (!dir_sd)
		return -ENOENT;

	sysfs_addrm_start(&acxt, dir_sd);

	sd = sysfs_find_dirent(dir_sd, ns, name);
	if (sd && (sd->s_ns != ns))
		sd = NULL;
	if (sd)
		sysfs_remove_one(&acxt, sd);

	sysfs_addrm_finish(&acxt);

	if (sd)
		return 0;
	else
		return -ENOENT;
}

int sysfs_permission(struct inode *inode, int mask, unsigned int flags)
{
	struct sysfs_dirent *sd;

	if (flags & IPERM_FLAG_RCU)
		return -ECHILD;

	sd = inode->i_private;

	mutex_lock(&sysfs_mutex);
	sysfs_refresh_inode(sd, inode);
	mutex_unlock(&sysfs_mutex);

	return generic_permission(inode, mask, flags, NULL);
}
Commit	Line	Data
1da177e4	1	/*
6d66f5cd	2	* fs/sysfs/inode.c - basic sysfs inode and dentry operations
1da177e4	3	*
6d66f5cd TH	4	* Copyright (c) 2001-3 Patrick Mochel
	5	* Copyright (c) 2007 SUSE Linux Products GmbH
	6	* Copyright (c) 2007 Tejun Heo <[email protected]>
	7	*
	8	* This file is released under the GPLv2.
1da177e4 LT	9	*
	10	* Please see Documentation/filesystems/sysfs.txt for more information.
	11	*/
	12
	13	#undef DEBUG
	14
	15	#include <linux/pagemap.h>
	16	#include <linux/namei.h>
	17	#include <linux/backing-dev.h>
16f7e0fe	18	#include <linux/capability.h>
995982ca	19	#include <linux/errno.h>
e8edc6e0	20	#include <linux/sched.h>
5a0e3ad6	21	#include <linux/slab.h>
57cc7215	22	#include <linux/sysfs.h>
ddd29ec6 DQ	23	#include <linux/xattr.h>
ddd29ec6 DQ	24	#include <linux/security.h>
1da177e4 LT	25	#include "sysfs.h"
	26
	27	extern struct super_block * sysfs_sb;
	28
f5e54d6e	29	static const struct address_space_operations sysfs_aops = {
1da177e4	30	.readpage = simple_readpage,
800d15a5 NP	31	.write_begin = simple_write_begin,
800d15a5 NP	32	.write_end = simple_write_end,
1da177e4 LT	33	};
	34
	35	static struct backing_dev_info sysfs_backing_dev_info = {
d993831f	36	.name = "sysfs",
1da177e4	37	.ra_pages = 0, /* No readahead */
e4ad08fe	38	.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
1da177e4 LT	39	};
1da177e4 LT	40
c5ef1c42	41	static const struct inode_operations sysfs_inode_operations ={
e61ab4ae	42	.permission = sysfs_permission,
988d186d	43	.setattr = sysfs_setattr,
e61ab4ae	44	.getattr = sysfs_getattr,
ddd29ec6	45	.setxattr = sysfs_setxattr,
988d186d MS	46	};
988d186d MS	47
e0bf68dd PZ	48	int __init sysfs_inode_init(void)
	49	{
	50	return bdi_init(&sysfs_backing_dev_info);
	51	}
	52
f38506c4	53	static struct sysfs_inode_attrs sysfs_init_inode_attrs(struct sysfs_dirent sd)
ddd29ec6 DQ	54	{
	55	struct sysfs_inode_attrs *attrs;
	56	struct iattr *iattrs;
	57
	58	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	59	if (!attrs)
	60	return NULL;
	61	iattrs = &attrs->ia_iattr;
	62
	63	/* assign default attributes */
	64	iattrs->ia_mode = sd->s_mode;
	65	iattrs->ia_uid = 0;
	66	iattrs->ia_gid = 0;
	67	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
	68
	69	return attrs;
	70	}
f38506c4	71
35df63c4	72	int sysfs_sd_setattr(struct sysfs_dirent sd, struct iattr iattr)
988d186d	73	{
ddd29ec6 DQ	74	struct sysfs_inode_attrs *sd_attrs;
ddd29ec6 DQ	75	struct iattr *iattrs;
988d186d	76	unsigned int ia_valid = iattr->ia_valid;
988d186d	77
ddd29ec6	78	sd_attrs = sd->s_iattr;
988d186d	79
ddd29ec6	80	if (!sd_attrs) {
988d186d	81	/* setting attributes for the first time, allocate now */
ddd29ec6 DQ	82	sd_attrs = sysfs_init_inode_attrs(sd);
ddd29ec6 DQ	83	if (!sd_attrs)
988d186d	84	return -ENOMEM;
ddd29ec6	85	sd->s_iattr = sd_attrs;
7c0ff870 EB	86	}
	87	/* attributes were changed at least once in past */
	88	iattrs = &sd_attrs->ia_iattr;
	89
	90	if (ia_valid & ATTR_UID)
	91	iattrs->ia_uid = iattr->ia_uid;
	92	if (ia_valid & ATTR_GID)
	93	iattrs->ia_gid = iattr->ia_gid;
	94	if (ia_valid & ATTR_ATIME)
	95	iattrs->ia_atime = iattr->ia_atime;
	96	if (ia_valid & ATTR_MTIME)
	97	iattrs->ia_mtime = iattr->ia_mtime;
	98	if (ia_valid & ATTR_CTIME)
	99	iattrs->ia_ctime = iattr->ia_ctime;
	100	if (ia_valid & ATTR_MODE) {
	101	umode_t mode = iattr->ia_mode;
	102	iattrs->ia_mode = sd->s_mode = mode;
988d186d	103	}
35df63c4 EB	104	return 0;
	105	}
	106
	107	int sysfs_setattr(struct dentry dentry, struct iattr iattr)
	108	{
	109	struct inode *inode = dentry->d_inode;
	110	struct sysfs_dirent *sd = dentry->d_fsdata;
	111	int error;
	112
	113	if (!sd)
	114	return -EINVAL;
	115
f8d4f618	116	mutex_lock(&sysfs_mutex);
35df63c4 EB	117	error = inode_change_ok(inode, iattr);
35df63c4 EB	118	if (error)
f8d4f618	119	goto out;
35df63c4	120
75de46b9 NP	121	error = sysfs_sd_setattr(sd, iattr);
	122	if (error)
	123	goto out;
	124
3322e79a	125	/* this ignores size changes */
6a1a90ad	126	setattr_copy(inode, iattr);
35df63c4	127
f8d4f618	128	out:
35df63c4	129	mutex_unlock(&sysfs_mutex);
ddd29ec6 DQ	130	return error;
ddd29ec6 DQ	131	}
988d186d	132
f44d3e78 EB	133	static int sysfs_sd_setsecdata(struct sysfs_dirent sd, void secdata, u32 secdata_len)
	134	{
	135	struct sysfs_inode_attrs *iattrs;
	136	void *old_secdata;
	137	size_t old_secdata_len;
	138
	139	iattrs = sd->s_iattr;
	140	if (!iattrs)
	141	iattrs = sysfs_init_inode_attrs(sd);
	142	if (!iattrs)
	143	return -ENOMEM;
	144
	145	old_secdata = iattrs->ia_secdata;
	146	old_secdata_len = iattrs->ia_secdata_len;
	147
	148	iattrs->ia_secdata = *secdata;
	149	iattrs->ia_secdata_len = *secdata_len;
	150
	151	*secdata = old_secdata;
	152	*secdata_len = old_secdata_len;
	153	return 0;
	154	}
	155
ddd29ec6 DQ	156	int sysfs_setxattr(struct dentry dentry, const char name, const void *value,
	157	size_t size, int flags)
	158	{
	159	struct sysfs_dirent *sd = dentry->d_fsdata;
ddd29ec6 DQ	160	void *secdata;
	161	int error;
	162	u32 secdata_len = 0;
	163
	164	if (!sd)
	165	return -EINVAL;
ddd29ec6 DQ	166
	167	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
	168	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
	169	error = security_inode_setsecurity(dentry->d_inode, suffix,
	170	value, size, flags);
	171	if (error)
	172	goto out;
	173	error = security_inode_getsecctx(dentry->d_inode,
	174	&secdata, &secdata_len);
	175	if (error)
	176	goto out;
988d186d	177
f44d3e78 EB	178	mutex_lock(&sysfs_mutex);
	179	error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
	180	mutex_unlock(&sysfs_mutex);
	181
	182	if (secdata)
	183	security_release_secctx(secdata, secdata_len);
ddd29ec6 DQ	184	} else
	185	return -EINVAL;
	186	out:
988d186d MS	187	return error;
	188	}
	189
8215534c MS	190	static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
	191	{
	192	inode->i_mode = mode;
8215534c MS	193	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	194	}
	195
	196	static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
	197	{
8215534c MS	198	inode->i_uid = iattr->ia_uid;
	199	inode->i_gid = iattr->ia_gid;
	200	inode->i_atime = iattr->ia_atime;
	201	inode->i_mtime = iattr->ia_mtime;
	202	inode->i_ctime = iattr->ia_ctime;
	203	}
	204
372e88bd EB	205	static int sysfs_count_nlink(struct sysfs_dirent *sd)
	206	{
	207	struct sysfs_dirent *child;
	208	int nr = 0;
	209
bc747f37	210	for (child = sd->s_dir.children; child; child = child->s_sibling)
372e88bd EB	211	if (sysfs_type(child) == SYSFS_DIR)
	212	nr++;
	213
	214	return nr + 2;
	215	}
	216
e61ab4ae EB	217	static void sysfs_refresh_inode(struct sysfs_dirent sd, struct inode inode)
	218	{
	219	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
	220
	221	inode->i_mode = sd->s_mode;
	222	if (iattrs) {
	223	/* sysfs_dirent has non-default attributes
	224	* get them from persistent copy in sysfs_dirent
	225	*/
	226	set_inode_attr(inode, &iattrs->ia_iattr);
	227	security_inode_notifysecctx(inode,
	228	iattrs->ia_secdata,
	229	iattrs->ia_secdata_len);
	230	}
	231
	232	if (sysfs_type(sd) == SYSFS_DIR)
	233	inode->i_nlink = sysfs_count_nlink(sd);
	234	}
	235
	236	int sysfs_getattr(struct vfsmount mnt, struct dentry dentry, struct kstat *stat)
	237	{
	238	struct sysfs_dirent *sd = dentry->d_fsdata;
	239	struct inode *inode = dentry->d_inode;
	240
	241	mutex_lock(&sysfs_mutex);
	242	sysfs_refresh_inode(sd, inode);
	243	mutex_unlock(&sysfs_mutex);
	244
	245	generic_fillattr(inode, stat);
	246	return 0;
	247	}
	248
bc37e283	249	static void sysfs_init_inode(struct sysfs_dirent sd, struct inode inode)
1da177e4	250	{
372e88bd EB	251	struct bin_attribute *bin_attr;
372e88bd EB	252
04256b4a	253	inode->i_private = sysfs_get(sd);
fc9f54b9 TH	254	inode->i_mapping->a_ops = &sysfs_aops;
	255	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	256	inode->i_op = &sysfs_inode_operations;
fc9f54b9	257
e61ab4ae EB	258	set_default_inode_attr(inode, sd->s_mode);
e61ab4ae EB	259	sysfs_refresh_inode(sd, inode);
372e88bd	260
372e88bd EB	261	/* initialize inode according to type */
372e88bd EB	262	switch (sysfs_type(sd)) {
372e88bd EB	263	case SYSFS_DIR:
	264	inode->i_op = &sysfs_dir_inode_operations;
	265	inode->i_fop = &sysfs_dir_operations;
372e88bd EB	266	break;
	267	case SYSFS_KOBJ_ATTR:
	268	inode->i_size = PAGE_SIZE;
	269	inode->i_fop = &sysfs_file_operations;
	270	break;
	271	case SYSFS_KOBJ_BIN_ATTR:
b1fc3d61	272	bin_attr = sd->s_bin_attr.bin_attr;
372e88bd EB	273	inode->i_size = bin_attr->size;
	274	inode->i_fop = &bin_fops;
	275	break;
	276	case SYSFS_KOBJ_LINK:
	277	inode->i_op = &sysfs_symlink_inode_operations;
	278	break;
	279	default:
	280	BUG();
	281	}
	282
	283	unlock_new_inode(inode);
fc9f54b9 TH	284	}
	285
	286	/**
8312a8d7	287	* sysfs_get_inode - get inode for sysfs_dirent
fac2622b	288	* @sb: super block
fc9f54b9 TH	289	* @sd: sysfs_dirent to allocate inode for
fc9f54b9 TH	290	*
8312a8d7 TH	291	* Get inode for @sd. If such inode doesn't exist, a new inode
	292	* is allocated and basics are initialized. New inode is
	293	* returned locked.
fc9f54b9 TH	294	*
	295	* LOCKING:
	296	* Kernel thread context (may sleep).
	297	*
	298	* RETURNS:
	299	* Pointer to allocated inode on success, NULL on failure.
	300	*/
fac2622b	301	struct inode * sysfs_get_inode(struct super_block sb, struct sysfs_dirent sd)
fc9f54b9 TH	302	{
	303	struct inode *inode;
	304
fac2622b	305	inode = iget_locked(sb, sd->s_ino);
8312a8d7	306	if (inode && (inode->i_state & I_NEW))
fc9f54b9 TH	307	sysfs_init_inode(sd, inode);
fc9f54b9 TH	308
1da177e4 LT	309	return inode;
	310	}
	311
04256b4a EB	312	/*
	313	* The sysfs_dirent serves as both an inode and a directory entry for sysfs.
	314	* To prevent the sysfs inode numbers from being freed prematurely we take a
	315	* reference to sysfs_dirent from the sysfs inode. A
01cd9fef	316	* super_operations.evict_inode() implementation is needed to drop that
04256b4a EB	317	* reference upon inode destruction.
04256b4a EB	318	*/
01cd9fef	319	void sysfs_evict_inode(struct inode *inode)
04256b4a EB	320	{
	321	struct sysfs_dirent *sd = inode->i_private;
	322
	323	truncate_inode_pages(&inode->i_data, 0);
01cd9fef	324	end_writeback(inode);
04256b4a EB	325	sysfs_put(sd);
	326	}
	327
3ff195b0	328	int sysfs_hash_and_remove(struct sysfs_dirent dir_sd, const void ns, const char *name)
1da177e4	329	{
fb6896da	330	struct sysfs_addrm_cxt acxt;
41fc1c27	331	struct sysfs_dirent *sd;
641e6f30	332
608e266a	333	if (!dir_sd)
995982ca	334	return -ENOENT;
1da177e4	335
fb6896da	336	sysfs_addrm_start(&acxt, dir_sd);
608e266a	337
3ff195b0	338	sd = sysfs_find_dirent(dir_sd, ns, name);
af10ec77 EB	339	if (sd && (sd->s_ns != ns))
af10ec77 EB	340	sd = NULL;
41fc1c27 TH	341	if (sd)
41fc1c27 TH	342	sysfs_remove_one(&acxt, sd);
3007e997	343
990e53f8 TH	344	sysfs_addrm_finish(&acxt);
	345
	346	if (sd)
fb6896da	347	return 0;
990e53f8 TH	348	else
990e53f8 TH	349	return -ENOENT;
1da177e4	350	}
e61ab4ae	351
b74c79e9	352	int sysfs_permission(struct inode *inode, int mask, unsigned int flags)
e61ab4ae	353	{
b74c79e9 NP	354	struct sysfs_dirent *sd;
	355
	356	if (flags & IPERM_FLAG_RCU)
	357	return -ECHILD;
	358
	359	sd = inode->i_private;
e61ab4ae EB	360
	361	mutex_lock(&sysfs_mutex);
	362	sysfs_refresh_inode(sd, inode);
	363	mutex_unlock(&sysfs_mutex);
	364
b74c79e9	365	return generic_permission(inode, mask, flags, NULL);
e61ab4ae	366	}