fs/aufs/sysaufs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2005-2021 Junjiro R. Okajima
   4  *
   5  * This program, aufs is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 /*
  20  * sysfs interface and lifetime management
  21  * they are necessary regardless sysfs is disabled.
  22  */
  23
  24 #include <linux/random.h>
  25 #include "aufs.h"
  26
  27 unsigned long sysaufs_si_mask;
  28 struct kset *sysaufs_kset;
  29
  30 #define AuSiAttr(_name) { \
  31         .attr   = { .name = __stringify(_name), .mode = 0444 }, \
  32         .show   = sysaufs_si_##_name,                           \
  33 }
  34
  35 static struct sysaufs_si_attr sysaufs_si_attr_xi_path = AuSiAttr(xi_path);
  36 struct attribute *sysaufs_si_attrs[] = {
  37         &sysaufs_si_attr_xi_path.attr,
  38         NULL,
  39 };
  40
  41 static const struct sysfs_ops au_sbi_ops = {
  42         .show   = sysaufs_si_show
  43 };
  44
  45 static struct kobj_type au_sbi_ktype = {
  46         .release        = au_si_free,
  47         .sysfs_ops      = &au_sbi_ops,
  48         .default_attrs  = sysaufs_si_attrs
  49 };
  50
  51 /* ---------------------------------------------------------------------- */
  52
  53 int sysaufs_si_init(struct au_sbinfo *sbinfo)
  54 {
  55         int err;
  56
  57         sbinfo->si_kobj.kset = sysaufs_kset;
  58         /* cf. sysaufs_name() */
  59         err = kobject_init_and_add
  60                 (&sbinfo->si_kobj, &au_sbi_ktype, /*&sysaufs_kset->kobj*/NULL,
  61                  SysaufsSiNamePrefix "%lx", sysaufs_si_id(sbinfo));
  62
  63         return err;
  64 }
  65
  66 void sysaufs_fin(void)
  67 {
  68         sysfs_remove_group(&sysaufs_kset->kobj, sysaufs_attr_group);
  69         kset_unregister(sysaufs_kset);
  70 }
  71
  72 int __init sysaufs_init(void)
  73 {
  74         int err;
  75
  76         do {
  77                 get_random_bytes(&sysaufs_si_mask, sizeof(sysaufs_si_mask));
  78         } while (!sysaufs_si_mask);
  79
  80         err = -EINVAL;
  81         sysaufs_kset = kset_create_and_add(AUFS_NAME, NULL, fs_kobj);
  82         if (unlikely(!sysaufs_kset))
  83                 goto out;
  84         err = PTR_ERR(sysaufs_kset);
  85         if (IS_ERR(sysaufs_kset))
  86                 goto out;
  87         err = sysfs_create_group(&sysaufs_kset->kobj, sysaufs_attr_group);
  88         if (unlikely(err))
  89                 kset_unregister(sysaufs_kset);
  90
  91 out:
  92         return err;
  93 }