linux/fs/sysfs/inode.c at master · fabgithub/linux · GitHub

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* fs/sysfs/inode.c - basic sysfs inode and dentry operations

* 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"

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 = GLOBAL_ROOT_UID;

iattrs->ia_gid = GLOBAL_ROOT_GID;

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;

if (!sd->s_iattr) {

sd->s_iattr = sysfs_init_inode_attrs(sd);

if (!sd->s_iattr)

return -ENOMEM;

}

iattrs = sd->s_iattr;

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, umode_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 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)

set_nlink(inode, sd->s_dir.subdirs + 2);

}

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);

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) {

WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",

name);

return -ENOENT;

}

sysfs_addrm_start(&acxt, dir_sd);

sd = sysfs_find_dirent(dir_sd, ns, name);

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;

if (mask & MAY_NOT_BLOCK)

return -ECHILD;

sd = inode->i_private;

mutex_lock(&sysfs_mutex);

sysfs_refresh_inode(sd, inode);

mutex_unlock(&sysfs_mutex);

return generic_permission(inode, mask);

}

linux/fs/sysfs/inode.c at master · fabgithub/linux · GitHub

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