[net-next-2.6.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 <teheo@suse.de>
 *
 * 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/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 */
	generic_setattr(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.delete_inode() implementation is needed to drop that
 * reference upon inode destruction.
 */
void sysfs_delete_inode(struct inode *inode)
{
	struct sysfs_dirent *sd  = inode->i_private;

	truncate_inode_pages(&inode->i_data, 0);
	clear_inode(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)
{
	struct sysfs_dirent *sd = inode->i_private;

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

	return generic_permission(inode, mask, 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 <teheo@suse.de>
	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>
ddd29ec6 DQ	22	#include <linux/xattr.h>
ddd29ec6 DQ	23	#include <linux/security.h>
1da177e4 LT	24	#include "sysfs.h"
	25
	26	extern struct super_block * sysfs_sb;
	27
f5e54d6e	28	static const struct address_space_operations sysfs_aops = {
1da177e4	29	.readpage = simple_readpage,
800d15a5 NP	30	.write_begin = simple_write_begin,
800d15a5 NP	31	.write_end = simple_write_end,
1da177e4 LT	32	};
	33
	34	static struct backing_dev_info sysfs_backing_dev_info = {
d993831f	35	.name = "sysfs",
1da177e4	36	.ra_pages = 0, /* No readahead */
e4ad08fe	37	.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
1da177e4 LT	38	};
1da177e4 LT	39
c5ef1c42	40	static const struct inode_operations sysfs_inode_operations ={
e61ab4ae	41	.permission = sysfs_permission,
988d186d	42	.setattr = sysfs_setattr,
e61ab4ae	43	.getattr = sysfs_getattr,
ddd29ec6	44	.setxattr = sysfs_setxattr,
988d186d MS	45	};
988d186d MS	46
e0bf68dd PZ	47	int __init sysfs_inode_init(void)
	48	{
	49	return bdi_init(&sysfs_backing_dev_info);
	50	}
	51
f38506c4	52	static struct sysfs_inode_attrs sysfs_init_inode_attrs(struct sysfs_dirent sd)
ddd29ec6 DQ	53	{
	54	struct sysfs_inode_attrs *attrs;
	55	struct iattr *iattrs;
	56
	57	attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
	58	if (!attrs)
	59	return NULL;
	60	iattrs = &attrs->ia_iattr;
	61
	62	/* assign default attributes */
	63	iattrs->ia_mode = sd->s_mode;
	64	iattrs->ia_uid = 0;
	65	iattrs->ia_gid = 0;
	66	iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
	67
	68	return attrs;
	69	}
f38506c4	70
35df63c4	71	int sysfs_sd_setattr(struct sysfs_dirent sd, struct iattr iattr)
988d186d	72	{
ddd29ec6 DQ	73	struct sysfs_inode_attrs *sd_attrs;
ddd29ec6 DQ	74	struct iattr *iattrs;
988d186d	75	unsigned int ia_valid = iattr->ia_valid;
988d186d	76
ddd29ec6	77	sd_attrs = sd->s_iattr;
988d186d	78
ddd29ec6	79	if (!sd_attrs) {
988d186d	80	/* setting attributes for the first time, allocate now */
ddd29ec6 DQ	81	sd_attrs = sysfs_init_inode_attrs(sd);
ddd29ec6 DQ	82	if (!sd_attrs)
988d186d	83	return -ENOMEM;
ddd29ec6	84	sd->s_iattr = sd_attrs;
7c0ff870 EB	85	}
	86	/* attributes were changed at least once in past */
	87	iattrs = &sd_attrs->ia_iattr;
	88
	89	if (ia_valid & ATTR_UID)
	90	iattrs->ia_uid = iattr->ia_uid;
	91	if (ia_valid & ATTR_GID)
	92	iattrs->ia_gid = iattr->ia_gid;
	93	if (ia_valid & ATTR_ATIME)
	94	iattrs->ia_atime = iattr->ia_atime;
	95	if (ia_valid & ATTR_MTIME)
	96	iattrs->ia_mtime = iattr->ia_mtime;
	97	if (ia_valid & ATTR_CTIME)
	98	iattrs->ia_ctime = iattr->ia_ctime;
	99	if (ia_valid & ATTR_MODE) {
	100	umode_t mode = iattr->ia_mode;
	101	iattrs->ia_mode = sd->s_mode = mode;
988d186d	102	}
35df63c4 EB	103	return 0;
	104	}
	105
	106	int sysfs_setattr(struct dentry dentry, struct iattr iattr)
	107	{
	108	struct inode *inode = dentry->d_inode;
	109	struct sysfs_dirent *sd = dentry->d_fsdata;
	110	int error;
	111
	112	if (!sd)
	113	return -EINVAL;
	114
f8d4f618	115	mutex_lock(&sysfs_mutex);
35df63c4 EB	116	error = inode_change_ok(inode, iattr);
35df63c4 EB	117	if (error)
f8d4f618	118	goto out;
35df63c4	119
8718d36c NP	120	error = sysfs_sd_setattr(sd, iattr);
	121	if (error)
	122	goto out;
	123
3322e79a NP	124	/* this ignores size changes */
3322e79a NP	125	generic_setattr(inode, iattr);
35df63c4	126
f8d4f618	127	out:
35df63c4	128	mutex_unlock(&sysfs_mutex);
ddd29ec6 DQ	129	return error;
ddd29ec6 DQ	130	}
988d186d	131
f44d3e78 EB	132	static int sysfs_sd_setsecdata(struct sysfs_dirent sd, void secdata, u32 secdata_len)
	133	{
	134	struct sysfs_inode_attrs *iattrs;
	135	void *old_secdata;
	136	size_t old_secdata_len;
	137
	138	iattrs = sd->s_iattr;
	139	if (!iattrs)
	140	iattrs = sysfs_init_inode_attrs(sd);
	141	if (!iattrs)
	142	return -ENOMEM;
	143
	144	old_secdata = iattrs->ia_secdata;
	145	old_secdata_len = iattrs->ia_secdata_len;
	146
	147	iattrs->ia_secdata = *secdata;
	148	iattrs->ia_secdata_len = *secdata_len;
	149
	150	*secdata = old_secdata;
	151	*secdata_len = old_secdata_len;
	152	return 0;
	153	}
	154
ddd29ec6 DQ	155	int sysfs_setxattr(struct dentry dentry, const char name, const void *value,
	156	size_t size, int flags)
	157	{
	158	struct sysfs_dirent *sd = dentry->d_fsdata;
ddd29ec6 DQ	159	void *secdata;
	160	int error;
	161	u32 secdata_len = 0;
	162
	163	if (!sd)
	164	return -EINVAL;
ddd29ec6 DQ	165
	166	if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
	167	const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
	168	error = security_inode_setsecurity(dentry->d_inode, suffix,
	169	value, size, flags);
	170	if (error)
	171	goto out;
	172	error = security_inode_getsecctx(dentry->d_inode,
	173	&secdata, &secdata_len);
	174	if (error)
	175	goto out;
988d186d	176
f44d3e78 EB	177	mutex_lock(&sysfs_mutex);
	178	error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
	179	mutex_unlock(&sysfs_mutex);
	180
	181	if (secdata)
	182	security_release_secctx(secdata, secdata_len);
ddd29ec6 DQ	183	} else
	184	return -EINVAL;
	185	out:
988d186d MS	186	return error;
	187	}
	188
8215534c MS	189	static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
	190	{
	191	inode->i_mode = mode;
8215534c MS	192	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
	193	}
	194
	195	static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
	196	{
8215534c MS	197	inode->i_uid = iattr->ia_uid;
	198	inode->i_gid = iattr->ia_gid;
	199	inode->i_atime = iattr->ia_atime;
	200	inode->i_mtime = iattr->ia_mtime;
	201	inode->i_ctime = iattr->ia_ctime;
	202	}
	203
372e88bd EB	204	static int sysfs_count_nlink(struct sysfs_dirent *sd)
	205	{
	206	struct sysfs_dirent *child;
	207	int nr = 0;
	208
bc747f37	209	for (child = sd->s_dir.children; child; child = child->s_sibling)
372e88bd EB	210	if (sysfs_type(child) == SYSFS_DIR)
	211	nr++;
	212
	213	return nr + 2;
	214	}
	215
e61ab4ae EB	216	static void sysfs_refresh_inode(struct sysfs_dirent sd, struct inode inode)
	217	{
	218	struct sysfs_inode_attrs *iattrs = sd->s_iattr;
	219
	220	inode->i_mode = sd->s_mode;
	221	if (iattrs) {
	222	/* sysfs_dirent has non-default attributes
	223	* get them from persistent copy in sysfs_dirent
	224	*/
	225	set_inode_attr(inode, &iattrs->ia_iattr);
	226	security_inode_notifysecctx(inode,
	227	iattrs->ia_secdata,
	228	iattrs->ia_secdata_len);
	229	}
	230
	231	if (sysfs_type(sd) == SYSFS_DIR)
	232	inode->i_nlink = sysfs_count_nlink(sd);
	233	}
	234
	235	int sysfs_getattr(struct vfsmount mnt, struct dentry dentry, struct kstat *stat)
	236	{
	237	struct sysfs_dirent *sd = dentry->d_fsdata;
	238	struct inode *inode = dentry->d_inode;
	239
	240	mutex_lock(&sysfs_mutex);
	241	sysfs_refresh_inode(sd, inode);
	242	mutex_unlock(&sysfs_mutex);
	243
	244	generic_fillattr(inode, stat);
	245	return 0;
	246	}
	247
bc37e283	248	static void sysfs_init_inode(struct sysfs_dirent sd, struct inode inode)
1da177e4	249	{
372e88bd EB	250	struct bin_attribute *bin_attr;
372e88bd EB	251
04256b4a	252	inode->i_private = sysfs_get(sd);
fc9f54b9 TH	253	inode->i_mapping->a_ops = &sysfs_aops;
	254	inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
	255	inode->i_op = &sysfs_inode_operations;
fc9f54b9	256
e61ab4ae EB	257	set_default_inode_attr(inode, sd->s_mode);
e61ab4ae EB	258	sysfs_refresh_inode(sd, inode);
372e88bd	259
372e88bd EB	260	/* initialize inode according to type */
372e88bd EB	261	switch (sysfs_type(sd)) {
372e88bd EB	262	case SYSFS_DIR:
	263	inode->i_op = &sysfs_dir_inode_operations;
	264	inode->i_fop = &sysfs_dir_operations;
372e88bd EB	265	break;
	266	case SYSFS_KOBJ_ATTR:
	267	inode->i_size = PAGE_SIZE;
	268	inode->i_fop = &sysfs_file_operations;
	269	break;
	270	case SYSFS_KOBJ_BIN_ATTR:
b1fc3d61	271	bin_attr = sd->s_bin_attr.bin_attr;
372e88bd EB	272	inode->i_size = bin_attr->size;
	273	inode->i_fop = &bin_fops;
	274	break;
	275	case SYSFS_KOBJ_LINK:
	276	inode->i_op = &sysfs_symlink_inode_operations;
	277	break;
	278	default:
	279	BUG();
	280	}
	281
	282	unlock_new_inode(inode);
fc9f54b9 TH	283	}
	284
	285	/**
8312a8d7	286	* sysfs_get_inode - get inode for sysfs_dirent
fac2622b	287	* @sb: super block
fc9f54b9 TH	288	* @sd: sysfs_dirent to allocate inode for
fc9f54b9 TH	289	*
8312a8d7 TH	290	* Get inode for @sd. If such inode doesn't exist, a new inode
	291	* is allocated and basics are initialized. New inode is
	292	* returned locked.
fc9f54b9 TH	293	*
	294	* LOCKING:
	295	* Kernel thread context (may sleep).
	296	*
	297	* RETURNS:
	298	* Pointer to allocated inode on success, NULL on failure.
	299	*/
fac2622b	300	struct inode * sysfs_get_inode(struct super_block sb, struct sysfs_dirent sd)
fc9f54b9 TH	301	{
	302	struct inode *inode;
	303
fac2622b	304	inode = iget_locked(sb, sd->s_ino);
8312a8d7	305	if (inode && (inode->i_state & I_NEW))
fc9f54b9 TH	306	sysfs_init_inode(sd, inode);
fc9f54b9 TH	307
1da177e4 LT	308	return inode;
	309	}
	310
04256b4a EB	311	/*
	312	* The sysfs_dirent serves as both an inode and a directory entry for sysfs.
	313	* To prevent the sysfs inode numbers from being freed prematurely we take a
	314	* reference to sysfs_dirent from the sysfs inode. A
	315	* super_operations.delete_inode() implementation is needed to drop that
	316	* reference upon inode destruction.
	317	*/
	318	void sysfs_delete_inode(struct inode *inode)
	319	{
	320	struct sysfs_dirent *sd = inode->i_private;
	321
	322	truncate_inode_pages(&inode->i_data, 0);
	323	clear_inode(inode);
	324	sysfs_put(sd);
	325	}
	326
3ff195b0	327	int sysfs_hash_and_remove(struct sysfs_dirent dir_sd, const void ns, const char *name)
1da177e4	328	{
fb6896da	329	struct sysfs_addrm_cxt acxt;
41fc1c27	330	struct sysfs_dirent *sd;
641e6f30	331
608e266a	332	if (!dir_sd)
995982ca	333	return -ENOENT;
1da177e4	334
fb6896da	335	sysfs_addrm_start(&acxt, dir_sd);
608e266a	336
3ff195b0	337	sd = sysfs_find_dirent(dir_sd, ns, name);
af10ec77 EB	338	if (sd && (sd->s_ns != ns))
af10ec77 EB	339	sd = NULL;
41fc1c27 TH	340	if (sd)
41fc1c27 TH	341	sysfs_remove_one(&acxt, sd);
3007e997	342
990e53f8 TH	343	sysfs_addrm_finish(&acxt);
	344
	345	if (sd)
fb6896da	346	return 0;
990e53f8 TH	347	else
990e53f8 TH	348	return -ENOENT;
1da177e4	349	}
e61ab4ae EB	350
	351	int sysfs_permission(struct inode *inode, int mask)
	352	{
	353	struct sysfs_dirent *sd = inode->i_private;
	354
	355	mutex_lock(&sysfs_mutex);
	356	sysfs_refresh_inode(sd, inode);
	357	mutex_unlock(&sysfs_mutex);
	358
	359	return generic_permission(inode, mask, NULL);
	360	}