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