308 lines
7.5 KiB
C
308 lines
7.5 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 <linux/sched.h>
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#include <asm/semaphore.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 const struct inode_operations sysfs_inode_operations ={
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.setattr = sysfs_setattr,
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};
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void sysfs_delete_inode(struct inode *inode)
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{
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/* Free the shadowed directory inode operations */
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if (sysfs_is_shadowed_inode(inode)) {
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kfree(inode->i_op);
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inode->i_op = NULL;
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}
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return generic_delete_inode(inode);
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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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inode->i_ino = sd->s_ino;
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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 sysfs_dirent *sd, struct dentry *dentry, int mode,
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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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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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* sysfs_drop_dentry - drop dentry for the specified sysfs_dirent
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* @sd: target sysfs_dirent
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*
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* Drop dentry for @sd. @sd must have been unlinked from its
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* parent on entry to this function such that it can't be looked
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* up anymore.
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*
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* @sd->s_dentry which is protected with sysfs_lock points to the
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* currently associated dentry but we're not holding a reference
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* to it and racing with dput(). Grab dcache_lock and verify
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* dentry before dropping it. If @sd->s_dentry is NULL or dput()
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* beats us, no need to bother.
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*/
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void sysfs_drop_dentry(struct sysfs_dirent *sd)
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{
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struct dentry *dentry = NULL, *parent = NULL;
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struct inode *dir;
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struct timespec curtime;
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/* We're not holding a reference to ->s_dentry dentry but the
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* field will stay valid as long as sysfs_lock is held.
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*/
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spin_lock(&sysfs_lock);
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spin_lock(&dcache_lock);
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if (sd->s_dentry && sd->s_dentry->d_inode) {
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/* get dentry if it's there and dput() didn't kill it yet */
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dentry = dget_locked(sd->s_dentry);
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parent = dentry->d_parent;
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} else if (sd->s_parent->s_dentry->d_inode) {
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/* We need to update the parent even if dentry for the
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* victim itself doesn't exist.
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*/
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parent = dget_locked(sd->s_parent->s_dentry);
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}
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/* drop */
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if (dentry) {
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spin_lock(&dentry->d_lock);
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__d_drop(dentry);
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spin_unlock(&dentry->d_lock);
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}
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spin_unlock(&dcache_lock);
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spin_unlock(&sysfs_lock);
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/* nothing to do if the parent isn't in dcache */
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if (!parent)
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return;
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/* adjust nlink and update timestamp */
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dir = parent->d_inode;
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mutex_lock(&dir->i_mutex);
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curtime = CURRENT_TIME;
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dir->i_ctime = dir->i_mtime = curtime;
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if (dentry) {
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dentry->d_inode->i_ctime = curtime;
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drop_nlink(dentry->d_inode);
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if (sd->s_type & SYSFS_DIR) {
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drop_nlink(dentry->d_inode);
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drop_nlink(dir);
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/* XXX: unpin if directory, this will go away soon */
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dput(dentry);
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}
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}
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mutex_unlock(&dir->i_mutex);
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/* bye bye */
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if (dentry)
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dput(dentry);
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else
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dput(parent);
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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_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
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list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
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if (!sd->s_type)
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continue;
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if (!strcmp(sd->s_name, name)) {
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list_del_init(&sd->s_sibling);
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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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if (!found)
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return -ENOENT;
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sysfs_drop_dentry(sd);
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sysfs_deactivate(sd);
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sysfs_put(sd);
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return 0;
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}
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