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/*
* inode.c - basic inode and dentry operations.
*
* sysfs is Copyright (c) 2001-3 Patrick Mochel
*
* 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 "sysfs.h"
extern struct super_block * sysfs_sb;
static const struct address_space_operations sysfs_aops = {
.readpage = simple_readpage,
.prepare_write = simple_prepare_write,
.commit_write = simple_commit_write
};
static struct backing_dev_info sysfs_backing_dev_info = {
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
};
static struct inode_operations sysfs_inode_operations ={
.setattr = sysfs_setattr,
};
int sysfs_setattr(struct dentry * dentry, struct iattr * iattr)
{
struct inode * inode = dentry->d_inode;
struct sysfs_dirent * sd = dentry->d_fsdata;
struct iattr * sd_iattr;
unsigned int ia_valid = iattr->ia_valid;
int error;
if (!sd)
return -EINVAL;
sd_iattr = sd->s_iattr;
error = inode_change_ok(inode, iattr);
if (error)
return error;
error = inode_setattr(inode, iattr);
if (error)
return error;
if (!sd_iattr) {
/* setting attributes for the first time, allocate now */
sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
if (!sd_iattr)
return -ENOMEM;
/* assign default attributes */
sd_iattr->ia_mode = sd->s_mode;
sd_iattr->ia_uid = 0;
sd_iattr->ia_gid = 0;
sd_iattr->ia_atime = sd_iattr->ia_mtime = sd_iattr->ia_ctime = CURRENT_TIME;
sd->s_iattr = sd_iattr;
}
/* attributes were changed atleast once in past */
if (ia_valid & ATTR_UID)
sd_iattr->ia_uid = iattr->ia_uid;
if (ia_valid & ATTR_GID)
sd_iattr->ia_gid = iattr->ia_gid;
if (ia_valid & ATTR_ATIME)
sd_iattr->ia_atime = timespec_trunc(iattr->ia_atime,
inode->i_sb->s_time_gran);
if (ia_valid & ATTR_MTIME)
sd_iattr->ia_mtime = timespec_trunc(iattr->ia_mtime,
inode->i_sb->s_time_gran);
if (ia_valid & ATTR_CTIME)
sd_iattr->ia_ctime = timespec_trunc(iattr->ia_ctime,
inode->i_sb->s_time_gran);
if (ia_valid & ATTR_MODE) {
umode_t mode = iattr->ia_mode;
if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
mode &= ~S_ISGID;
sd_iattr->ia_mode = sd->s_mode = mode;
}
return error;
}
static inline void set_default_inode_attr(struct inode * inode, mode_t mode)
{
inode->i_mode = mode;
inode->i_uid = 0;
inode->i_gid = 0;
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_mode = iattr->ia_mode;
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;
}
/*
* sysfs has a different i_mutex lock order behavior for i_mutex than other
* filesystems; sysfs i_mutex is called in many places with subsystem locks
* held. At the same time, many of the VFS locking rules do not apply to
* sysfs at all (cross directory rename for example). To untangle this mess
* (which gives false positives in lockdep), we're giving sysfs inodes their
* own class for i_mutex.
*/
static struct lock_class_key sysfs_inode_imutex_key;
struct inode * sysfs_new_inode(mode_t mode, struct sysfs_dirent * sd)
{
struct inode * inode = new_inode(sysfs_sb);
if (inode) {
inode->i_blocks = 0;
inode->i_mapping->a_ops = &sysfs_aops;
inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
inode->i_op = &sysfs_inode_operations;
lockdep_set_class(&inode->i_mutex, &sysfs_inode_imutex_key);
if (sd->s_iattr) {
/* sysfs_dirent has non-default attributes
* get them for the new inode from persistent copy
* in sysfs_dirent
*/
set_inode_attr(inode, sd->s_iattr);
} else
set_default_inode_attr(inode, mode);
}
return inode;
}
int sysfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
{
int error = 0;
struct inode * inode = NULL;
if (dentry) {
if (!dentry->d_inode) {
struct sysfs_dirent * sd = dentry->d_fsdata;
if ((inode = sysfs_new_inode(mode, sd))) {
if (dentry->d_parent && dentry->d_parent->d_inode) {
struct inode *p_inode = dentry->d_parent->d_inode;
p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
}
goto Proceed;
}
else
error = -ENOMEM;
} else
error = -EEXIST;
} else
error = -ENOENT;
goto Done;
Proceed:
if (init)
error = init(inode);
if (!error) {
d_instantiate(dentry, inode);
if (S_ISDIR(mode))
dget(dentry); /* pin only directory dentry in core */
} else
iput(inode);
Done:
return error;
}
/*
* Get the name for corresponding element represented by the given sysfs_dirent
*/
const unsigned char * sysfs_get_name(struct sysfs_dirent *sd)
{
struct attribute * attr;
struct bin_attribute * bin_attr;
struct sysfs_symlink * sl;
BUG_ON(!sd || !sd->s_element);
switch (sd->s_type) {
case SYSFS_DIR:
/* Always have a dentry so use that */
return sd->s_dentry->d_name.name;
case SYSFS_KOBJ_ATTR:
attr = sd->s_element;
return attr->name;
case SYSFS_KOBJ_BIN_ATTR:
bin_attr = sd->s_element;
return bin_attr->attr.name;
case SYSFS_KOBJ_LINK:
sl = sd->s_element;
return sl->link_name;
}
return NULL;
}
/*
* Unhashes the dentry corresponding to given sysfs_dirent
* Called with parent inode's i_mutex held.
*/
void sysfs_drop_dentry(struct sysfs_dirent * sd, struct dentry * parent)
{
struct dentry * dentry = sd->s_dentry;
if (dentry) {
spin_lock(&dcache_lock);
spin_lock(&dentry->d_lock);
if (!(d_unhashed(dentry) && dentry->d_inode)) {
dget_locked(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
simple_unlink(parent->d_inode, dentry);
} else {
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
}
}
}
int sysfs_hash_and_remove(struct dentry * dir, const char * name)
{
struct sysfs_dirent * sd;
struct sysfs_dirent * parent_sd;
int found = 0;
if (!dir)
return -ENOENT;
if (dir->d_inode == NULL)
/* no inode means this hasn't been made visible yet */
return -ENOENT;
parent_sd = dir->d_fsdata;
mutex_lock(&dir->d_inode->i_mutex);
list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
if (!sd->s_element)
continue;
if (!strcmp(sysfs_get_name(sd), name)) {
list_del_init(&sd->s_sibling);
sysfs_drop_dentry(sd, dir);
sysfs_put(sd);
found = 1;
break;
}
}
mutex_unlock(&dir->d_inode->i_mutex);
return found ? 0 : -ENOENT;
}
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