fs/sysfs/mount.c

   1 /*
   2  * mount.c - operations for initializing and mounting sysfs.
   3  */
   4
   5 #define DEBUG
   6
   7 #include <linux/fs.h>
   8 #include <linux/mount.h>
   9 #include <linux/pagemap.h>
  10 #include <linux/init.h>
  11
  12 #include "sysfs.h"
  13
  14 /* Random magic number */
  15 #define SYSFS_MAGIC 0x62656572
  16
  17 struct vfsmount *sysfs_mount;
  18 struct super_block * sysfs_sb = NULL;
  19 struct kmem_cache *sysfs_dir_cachep;
  20
  21 static struct super_operations sysfs_ops = {
  22         .statfs         = simple_statfs,
  23         .drop_inode     = generic_delete_inode,
  24 };
  25
  26 static struct sysfs_dirent sysfs_root = {
  27         .s_sibling      = LIST_HEAD_INIT(sysfs_root.s_sibling),
  28         .s_children     = LIST_HEAD_INIT(sysfs_root.s_children),
  29         .s_element      = NULL,
  30         .s_type         = SYSFS_ROOT,
  31         .s_iattr        = NULL,
  32 };
  33
  34 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  35 {
  36         struct inode *inode;
  37         struct dentry *root;
  38
  39         sb->s_blocksize = PAGE_CACHE_SIZE;
  40         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  41         sb->s_magic = SYSFS_MAGIC;
  42         sb->s_op = &sysfs_ops;
  43         sb->s_time_gran = 1;
  44         sysfs_sb = sb;
  45
  46         inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  47                                  &sysfs_root);
  48         if (inode) {
  49                 inode->i_op = &sysfs_dir_inode_operations;
  50                 inode->i_fop = &sysfs_dir_operations;
  51                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  52                 inc_nlink(inode);
  53         } else {
  54                 pr_debug("sysfs: could not get root inode\n");
  55                 return -ENOMEM;
  56         }
  57
  58         root = d_alloc_root(inode);
  59         if (!root) {
  60                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  61                 iput(inode);
  62                 return -ENOMEM;
  63         }
  64         root->d_fsdata = &sysfs_root;
  65         sb->s_root = root;
  66         return 0;
  67 }
  68
  69 static int sysfs_get_sb(struct file_system_type *fs_type,
  70         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  71 {
  72         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  73 }
  74
  75 static struct file_system_type sysfs_fs_type = {
  76         .name           = "sysfs",
  77         .get_sb         = sysfs_get_sb,
  78         .kill_sb        = kill_litter_super,
  79 };
  80
  81 int __init sysfs_init(void)
  82 {
  83         int err = -ENOMEM;
  84
  85         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  86                                               sizeof(struct sysfs_dirent),
  87                                               0, 0, NULL, NULL);
  88         if (!sysfs_dir_cachep)
  89                 goto out;
  90
  91         err = register_filesystem(&sysfs_fs_type);
  92         if (!err) {
  93                 sysfs_mount = kern_mount(&sysfs_fs_type);
  94                 if (IS_ERR(sysfs_mount)) {
  95                         printk(KERN_ERR "sysfs: could not mount!\n");
  96                         err = PTR_ERR(sysfs_mount);
  97                         sysfs_mount = NULL;
  98                         unregister_filesystem(&sysfs_fs_type);
  99                         goto out_err;
 100                 }
 101         } else
 102                 goto out_err;
 103 out:
 104         return err;
 105 out_err:
 106         kmem_cache_destroy(sysfs_dir_cachep);
 107         sysfs_dir_cachep = NULL;
 108         goto out;
 109 }