367 lines
8.4 KiB
C
367 lines
8.4 KiB
C
/*
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* fs/sysfs/inode.c - basic sysfs inode and dentry operations
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* This file is released under the GPLv2.
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#undef DEBUG
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#include <linux/pagemap.h>
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#include <linux/namei.h>
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#include <linux/backing-dev.h>
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#include <linux/capability.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/sysfs.h>
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#include <linux/xattr.h>
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#include <linux/security.h>
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#include "sysfs.h"
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extern struct super_block * sysfs_sb;
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static const struct address_space_operations sysfs_aops = {
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.readpage = simple_readpage,
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.write_begin = simple_write_begin,
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.write_end = simple_write_end,
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};
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static struct backing_dev_info sysfs_backing_dev_info = {
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.name = "sysfs",
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
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};
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static const struct inode_operations sysfs_inode_operations ={
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.permission = sysfs_permission,
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.setattr = sysfs_setattr,
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.getattr = sysfs_getattr,
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.setxattr = sysfs_setxattr,
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};
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int __init sysfs_inode_init(void)
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{
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return bdi_init(&sysfs_backing_dev_info);
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}
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static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
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{
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struct sysfs_inode_attrs *attrs;
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struct iattr *iattrs;
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attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
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if (!attrs)
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return NULL;
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iattrs = &attrs->ia_iattr;
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/* assign default attributes */
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iattrs->ia_mode = sd->s_mode;
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iattrs->ia_uid = 0;
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iattrs->ia_gid = 0;
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iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
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return attrs;
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}
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int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
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{
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struct sysfs_inode_attrs *sd_attrs;
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struct iattr *iattrs;
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unsigned int ia_valid = iattr->ia_valid;
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sd_attrs = sd->s_iattr;
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if (!sd_attrs) {
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/* setting attributes for the first time, allocate now */
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sd_attrs = sysfs_init_inode_attrs(sd);
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if (!sd_attrs)
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return -ENOMEM;
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sd->s_iattr = sd_attrs;
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}
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/* attributes were changed at least once in past */
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iattrs = &sd_attrs->ia_iattr;
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if (ia_valid & ATTR_UID)
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iattrs->ia_uid = iattr->ia_uid;
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if (ia_valid & ATTR_GID)
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iattrs->ia_gid = iattr->ia_gid;
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if (ia_valid & ATTR_ATIME)
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iattrs->ia_atime = iattr->ia_atime;
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if (ia_valid & ATTR_MTIME)
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iattrs->ia_mtime = iattr->ia_mtime;
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if (ia_valid & ATTR_CTIME)
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iattrs->ia_ctime = iattr->ia_ctime;
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if (ia_valid & ATTR_MODE) {
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umode_t mode = iattr->ia_mode;
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iattrs->ia_mode = sd->s_mode = mode;
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}
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return 0;
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}
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int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
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{
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struct inode *inode = dentry->d_inode;
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struct sysfs_dirent *sd = dentry->d_fsdata;
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int error;
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if (!sd)
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return -EINVAL;
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mutex_lock(&sysfs_mutex);
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error = inode_change_ok(inode, iattr);
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if (error)
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goto out;
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error = sysfs_sd_setattr(sd, iattr);
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if (error)
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goto out;
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/* this ignores size changes */
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setattr_copy(inode, iattr);
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out:
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mutex_unlock(&sysfs_mutex);
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return error;
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}
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static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
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{
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struct sysfs_inode_attrs *iattrs;
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void *old_secdata;
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size_t old_secdata_len;
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iattrs = sd->s_iattr;
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if (!iattrs)
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iattrs = sysfs_init_inode_attrs(sd);
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if (!iattrs)
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return -ENOMEM;
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old_secdata = iattrs->ia_secdata;
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old_secdata_len = iattrs->ia_secdata_len;
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iattrs->ia_secdata = *secdata;
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iattrs->ia_secdata_len = *secdata_len;
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*secdata = old_secdata;
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*secdata_len = old_secdata_len;
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return 0;
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}
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int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
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size_t size, int flags)
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{
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struct sysfs_dirent *sd = dentry->d_fsdata;
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void *secdata;
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int error;
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u32 secdata_len = 0;
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if (!sd)
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return -EINVAL;
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if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
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const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
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error = security_inode_setsecurity(dentry->d_inode, suffix,
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value, size, flags);
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if (error)
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goto out;
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error = security_inode_getsecctx(dentry->d_inode,
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&secdata, &secdata_len);
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if (error)
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goto out;
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mutex_lock(&sysfs_mutex);
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error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
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mutex_unlock(&sysfs_mutex);
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if (secdata)
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security_release_secctx(secdata, secdata_len);
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} else
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return -EINVAL;
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out:
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return error;
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}
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static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
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{
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inode->i_mode = mode;
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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}
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static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
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{
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inode->i_uid = iattr->ia_uid;
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inode->i_gid = iattr->ia_gid;
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inode->i_atime = iattr->ia_atime;
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inode->i_mtime = iattr->ia_mtime;
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inode->i_ctime = iattr->ia_ctime;
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}
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static int sysfs_count_nlink(struct sysfs_dirent *sd)
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{
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struct sysfs_dirent *child;
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int nr = 0;
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for (child = sd->s_dir.children; child; child = child->s_sibling)
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if (sysfs_type(child) == SYSFS_DIR)
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nr++;
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return nr + 2;
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}
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static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
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{
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struct sysfs_inode_attrs *iattrs = sd->s_iattr;
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inode->i_mode = sd->s_mode;
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if (iattrs) {
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/* sysfs_dirent has non-default attributes
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* get them from persistent copy in sysfs_dirent
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*/
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set_inode_attr(inode, &iattrs->ia_iattr);
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security_inode_notifysecctx(inode,
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iattrs->ia_secdata,
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iattrs->ia_secdata_len);
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}
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if (sysfs_type(sd) == SYSFS_DIR)
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inode->i_nlink = sysfs_count_nlink(sd);
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}
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int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
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{
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struct sysfs_dirent *sd = dentry->d_fsdata;
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struct inode *inode = dentry->d_inode;
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mutex_lock(&sysfs_mutex);
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sysfs_refresh_inode(sd, inode);
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mutex_unlock(&sysfs_mutex);
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generic_fillattr(inode, stat);
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return 0;
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}
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static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
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{
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struct bin_attribute *bin_attr;
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inode->i_private = sysfs_get(sd);
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inode->i_mapping->a_ops = &sysfs_aops;
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inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
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inode->i_op = &sysfs_inode_operations;
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set_default_inode_attr(inode, sd->s_mode);
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sysfs_refresh_inode(sd, inode);
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/* initialize inode according to type */
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switch (sysfs_type(sd)) {
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case SYSFS_DIR:
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inode->i_op = &sysfs_dir_inode_operations;
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inode->i_fop = &sysfs_dir_operations;
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break;
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case SYSFS_KOBJ_ATTR:
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inode->i_size = PAGE_SIZE;
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inode->i_fop = &sysfs_file_operations;
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break;
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case SYSFS_KOBJ_BIN_ATTR:
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bin_attr = sd->s_bin_attr.bin_attr;
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inode->i_size = bin_attr->size;
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inode->i_fop = &bin_fops;
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break;
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case SYSFS_KOBJ_LINK:
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inode->i_op = &sysfs_symlink_inode_operations;
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break;
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default:
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BUG();
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}
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unlock_new_inode(inode);
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}
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/**
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* sysfs_get_inode - get inode for sysfs_dirent
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* @sb: super block
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* @sd: sysfs_dirent to allocate inode for
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*
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* Get inode for @sd. If such inode doesn't exist, a new inode
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* is allocated and basics are initialized. New inode is
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* returned locked.
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*
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* LOCKING:
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* Kernel thread context (may sleep).
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*
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* RETURNS:
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* Pointer to allocated inode on success, NULL on failure.
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*/
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struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
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{
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struct inode *inode;
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inode = iget_locked(sb, sd->s_ino);
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if (inode && (inode->i_state & I_NEW))
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sysfs_init_inode(sd, inode);
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return inode;
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}
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/*
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* The sysfs_dirent serves as both an inode and a directory entry for sysfs.
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* To prevent the sysfs inode numbers from being freed prematurely we take a
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* reference to sysfs_dirent from the sysfs inode. A
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* super_operations.evict_inode() implementation is needed to drop that
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* reference upon inode destruction.
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*/
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void sysfs_evict_inode(struct inode *inode)
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{
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struct sysfs_dirent *sd = inode->i_private;
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truncate_inode_pages(&inode->i_data, 0);
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end_writeback(inode);
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sysfs_put(sd);
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}
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int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const char *name)
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{
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struct sysfs_addrm_cxt acxt;
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struct sysfs_dirent *sd;
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if (!dir_sd)
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return -ENOENT;
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sysfs_addrm_start(&acxt, dir_sd);
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sd = sysfs_find_dirent(dir_sd, ns, name);
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if (sd && (sd->s_ns != ns))
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sd = NULL;
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if (sd)
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sysfs_remove_one(&acxt, sd);
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sysfs_addrm_finish(&acxt);
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if (sd)
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return 0;
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else
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return -ENOENT;
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}
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int sysfs_permission(struct inode *inode, int mask)
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{
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struct sysfs_dirent *sd;
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if (mask & MAY_NOT_BLOCK)
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return -ECHILD;
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sd = inode->i_private;
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mutex_lock(&sysfs_mutex);
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sysfs_refresh_inode(sd, inode);
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mutex_unlock(&sysfs_mutex);
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return generic_permission(inode, mask);
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}
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