LXR linux/fs/sysfs/dir.c

   1/*
   2 * fs/sysfs/dir.c - sysfs core and dir operation implementation
   3 *
   4 * Copyright (c) 2001-3 Patrick Mochel
   5 * Copyright (c) 2007 SUSE Linux Products GmbH
   6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   7 *
   8 * This file is released under the GPLv2.
   9 *
  10 * Please see Documentation/filesystems/sysfs.txt for more information.
  11 */
  12
  13#undef DEBUG
  14
  15#include <linux/fs.h>
  16#include <linux/kobject.h>
  17#include <linux/slab.h>
  18#include "sysfs.h"
  19
  20DEFINE_SPINLOCK(sysfs_symlink_target_lock);
  21
  22void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
  23{
  24        char *buf;
  25
  26        buf = kzalloc(PATH_MAX, GFP_KERNEL);
  27        if (buf)
  28                kernfs_path(parent, buf, PATH_MAX);
  29
  30        WARN(1, KERN_WARNING "sysfs: cannot create duplicate filename '%s/%s'\n",
  31             buf, name);
  32
  33        kfree(buf);
  34}
  35
  36/**
  37 * sysfs_create_dir_ns - create a directory for an object with a namespace tag
  38 * @kobj: object we're creating directory for
  39 * @ns: the namespace tag to use
  40 */
  41int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
  42{
  43        struct kernfs_node *parent, *kn;
  44
  45        BUG_ON(!kobj);
  46
  47        if (kobj->parent)
  48                parent = kobj->parent->sd;
  49        else
  50                parent = sysfs_root_kn;
  51
  52        if (!parent)
  53                return -ENOENT;
  54
  55        kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
  56                                  S_IRWXU | S_IRUGO | S_IXUGO, kobj, ns);
  57        if (IS_ERR(kn)) {
  58                if (PTR_ERR(kn) == -EEXIST)
  59                        sysfs_warn_dup(parent, kobject_name(kobj));
  60                return PTR_ERR(kn);
  61        }
  62
  63        kobj->sd = kn;
  64        return 0;
  65}
  66
  67/**
  68 *      sysfs_remove_dir - remove an object's directory.
  69 *      @kobj:  object.
  70 *
  71 *      The only thing special about this is that we remove any files in
  72 *      the directory before we remove the directory, and we've inlined
  73 *      what used to be sysfs_rmdir() below, instead of calling separately.
  74 */
  75void sysfs_remove_dir(struct kobject *kobj)
  76{
  77        struct kernfs_node *kn = kobj->sd;
  78
  79        /*
  80         * In general, kboject owner is responsible for ensuring removal
  81         * doesn't race with other operations and sysfs doesn't provide any
  82         * protection; however, when @kobj is used as a symlink target, the
  83         * symlinking entity usually doesn't own @kobj and thus has no
  84         * control over removal.  @kobj->sd may be removed anytime
  85         * and symlink code may end up dereferencing an already freed node.
  86         *
  87         * sysfs_symlink_target_lock synchronizes @kobj->sd
  88         * disassociation against symlink operations so that symlink code
  89         * can safely dereference @kobj->sd.
  90         */
  91        spin_lock(&sysfs_symlink_target_lock);
  92        kobj->sd = NULL;
  93        spin_unlock(&sysfs_symlink_target_lock);
  94
  95        if (kn) {
  96                WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
  97                kernfs_remove(kn);
  98        }
  99}
 100
 101int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
 102                        const void *new_ns)
 103{
 104        struct kernfs_node *parent;
 105        int ret;
 106
 107        parent = kernfs_get_parent(kobj->sd);
 108        ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
 109        kernfs_put(parent);
 110        return ret;
 111}
 112
 113int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
 114                      const void *new_ns)
 115{
 116        struct kernfs_node *kn = kobj->sd;
 117        struct kernfs_node *new_parent;
 118
 119        new_parent = new_parent_kobj && new_parent_kobj->sd ?
 120                new_parent_kobj->sd : sysfs_root_kn;
 121
 122        return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
 123}
 124
 125/**
 126 * sysfs_create_mount_point - create an always empty directory
 127 * @parent_kobj:  kobject that will contain this always empty directory
 128 * @name: The name of the always empty directory to add
 129 */
 130int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
 131{
 132        struct kernfs_node *kn, *parent = parent_kobj->sd;
 133
 134        kn = kernfs_create_empty_dir(parent, name);
 135        if (IS_ERR(kn)) {
 136                if (PTR_ERR(kn) == -EEXIST)
 137                        sysfs_warn_dup(parent, name);
 138                return PTR_ERR(kn);
 139        }
 140
 141        return 0;
 142}
 143EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
 144
 145/**
 146 *      sysfs_remove_mount_point - remove an always empty directory.
 147 *      @parent_kobj: kobject that will contain this always empty directory
 148 *      @name: The name of the always empty directory to remove
 149 *
 150 */
 151void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
 152{
 153        struct kernfs_node *parent = parent_kobj->sd;
 154
 155        kernfs_remove_by_name_ns(parent, name, NULL);
 156}
 157EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);
 158