fs/sysfs/mount.c

   1 /*
   2  * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
   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 #define DEBUG
  14
  15 #include <linux/fs.h>
  16 #include <linux/mount.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20
  21 #include "sysfs.h"
  22
  23 /* Random magic number */
  24 #define SYSFS_MAGIC 0x62656572
  25
  26 static struct vfsmount *sysfs_mount;
  27 struct super_block * sysfs_sb = NULL;
  28 struct kmem_cache *sysfs_dir_cachep;
  29
  30 static const struct super_operations sysfs_ops = {
  31         .statfs         = simple_statfs,
  32         .drop_inode     = generic_delete_inode,
  33 };
  34
  35 struct sysfs_dirent sysfs_root = {
  36         .s_name         = "",
  37         .s_count        = ATOMIC_INIT(1),
  38         .s_flags        = SYSFS_DIR,
  39         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  40         .s_ino          = 1,
  41 };
  42
  43 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  44 {
  45         struct inode *inode;
  46         struct dentry *root;
  47
  48         sb->s_blocksize = PAGE_CACHE_SIZE;
  49         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  50         sb->s_magic = SYSFS_MAGIC;
  51         sb->s_op = &sysfs_ops;
  52         sb->s_time_gran = 1;
  53         sysfs_sb = sb;
  54
  55         /* get root inode, initialize and unlock it */
  56         inode = sysfs_get_inode(&sysfs_root);
  57         if (!inode) {
  58                 pr_debug("sysfs: could not get root inode\n");
  59                 return -ENOMEM;
  60         }
  61
  62         /* instantiate and link root dentry */
  63         root = d_alloc_root(inode);
  64         if (!root) {
  65                 pr_debug("%s: could not get root dentry!\n",__func__);
  66                 iput(inode);
  67                 return -ENOMEM;
  68         }
  69         root->d_fsdata = &sysfs_root;
  70         sb->s_root = root;
  71         return 0;
  72 }
  73
  74 static int sysfs_get_sb(struct file_system_type *fs_type,
  75         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  76 {
  77         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  78 }
  79
  80 static struct file_system_type sysfs_fs_type = {
  81         .name           = "sysfs",
  82         .get_sb         = sysfs_get_sb,
  83         .kill_sb        = kill_anon_super,
  84 };
  85
  86 int __init sysfs_init(void)
  87 {
  88         int err = -ENOMEM;
  89
  90         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  91                                               sizeof(struct sysfs_dirent),
  92                                               0, 0, NULL);
  93         if (!sysfs_dir_cachep)
  94                 goto out;
  95
  96         err = sysfs_inode_init();
  97         if (err)
  98                 goto out_err;
  99
 100         err = register_filesystem(&sysfs_fs_type);
 101         if (!err) {
 102                 sysfs_mount = kern_mount(&sysfs_fs_type);
 103                 if (IS_ERR(sysfs_mount)) {
 104                         printk(KERN_ERR "sysfs: could not mount!\n");
 105                         err = PTR_ERR(sysfs_mount);
 106                         sysfs_mount = NULL;
 107                         unregister_filesystem(&sysfs_fs_type);
 108                         goto out_err;
 109                 }
 110         } else
 111                 goto out_err;
 112 out:
 113         return err;
 114 out_err:
 115         kmem_cache_destroy(sysfs_dir_cachep);
 116         sysfs_dir_cachep = NULL;
 117         goto out;
 118 }
 119
 120 #undef sysfs_get
 121 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
 122 {
 123         return __sysfs_get(sd);
 124 }
 125 EXPORT_SYMBOL_GPL(sysfs_get);
 126
 127 #undef sysfs_put
 128 void sysfs_put(struct sysfs_dirent *sd)
 129 {
 130         __sysfs_put(sd);
 131 }
 132 EXPORT_SYMBOL_GPL(sysfs_put);