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 #include <linux/magic.h>
  21
  22 #include "sysfs.h"
  23
  24
  25 static struct vfsmount *sysfs_mount;
  26 struct super_block * sysfs_sb = NULL;
  27 struct kmem_cache *sysfs_dir_cachep;
  28
  29 static const struct super_operations sysfs_ops = {
  30         .statfs         = simple_statfs,
  31         .drop_inode     = generic_delete_inode,
  32         .delete_inode   = sysfs_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         mutex_lock(&sysfs_mutex);
  57         inode = sysfs_get_inode(&sysfs_root);
  58         mutex_unlock(&sysfs_mutex);
  59         if (!inode) {
  60                 pr_debug("sysfs: could not get root inode\n");
  61                 return -ENOMEM;
  62         }
  63
  64         /* instantiate and link root dentry */
  65         root = d_alloc_root(inode);
  66         if (!root) {
  67                 pr_debug("%s: could not get root dentry!\n",__func__);
  68                 iput(inode);
  69                 return -ENOMEM;
  70         }
  71         root->d_fsdata = &sysfs_root;
  72         sb->s_root = root;
  73         return 0;
  74 }
  75
  76 static int sysfs_get_sb(struct file_system_type *fs_type,
  77         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  78 {
  79         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  80 }
  81
  82 static struct file_system_type sysfs_fs_type = {
  83         .name           = "sysfs",
  84         .get_sb         = sysfs_get_sb,
  85         .kill_sb        = kill_anon_super,
  86 };
  87
  88 int __init sysfs_init(void)
  89 {
  90         int err = -ENOMEM;
  91
  92         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  93                                               sizeof(struct sysfs_dirent),
  94                                               0, 0, NULL);
  95         if (!sysfs_dir_cachep)
  96                 goto out;
  97
  98         err = sysfs_inode_init();
  99         if (err)
 100                 goto out_err;
 101
 102         err = register_filesystem(&sysfs_fs_type);
 103         if (!err) {
 104                 sysfs_mount = kern_mount(&sysfs_fs_type);
 105                 if (IS_ERR(sysfs_mount)) {
 106                         printk(KERN_ERR "sysfs: could not mount!\n");
 107                         err = PTR_ERR(sysfs_mount);
 108                         sysfs_mount = NULL;
 109                         unregister_filesystem(&sysfs_fs_type);
 110                         goto out_err;
 111                 }
 112         } else
 113                 goto out_err;
 114 out:
 115         return err;
 116 out_err:
 117         kmem_cache_destroy(sysfs_dir_cachep);
 118         sysfs_dir_cachep = NULL;
 119         goto out;
 120 }
 121
 122 #undef sysfs_get
 123 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
 124 {
 125         return __sysfs_get(sd);
 126 }
 127 EXPORT_SYMBOL_GPL(sysfs_get);
 128
 129 #undef sysfs_put
 130 void sysfs_put(struct sysfs_dirent *sd)
 131 {
 132         __sysfs_put(sd);
 133 }
 134 EXPORT_SYMBOL_GPL(sysfs_put);