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 #include <asm/semaphore.h>
  12
  13 #include "sysfs.h"
  14
  15 /* Random magic number */
  16 #define SYSFS_MAGIC 0x62656572
  17
  18 struct vfsmount *sysfs_mount;
  19 struct super_block * sysfs_sb = NULL;
  20 struct kmem_cache *sysfs_dir_cachep;
  21
  22 static const struct super_operations sysfs_ops = {
  23         .statfs         = simple_statfs,
  24         .drop_inode     = sysfs_delete_inode,
  25 };
  26
  27 struct sysfs_dirent sysfs_root = {
  28         .s_count        = ATOMIC_INIT(1),
  29         .s_flags        = SYSFS_ROOT,
  30         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  31         .s_ino          = 1,
  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         /* get root inode, initialize and unlock it */
  47         inode = sysfs_get_inode(&sysfs_root);
  48         if (!inode) {
  49                 pr_debug("sysfs: could not get root inode\n");
  50                 return -ENOMEM;
  51         }
  52
  53         inode->i_op = &sysfs_dir_inode_operations;
  54         inode->i_fop = &sysfs_dir_operations;
  55         inc_nlink(inode); /* directory, account for "." */
  56         unlock_new_inode(inode);
  57
  58         /* instantiate and link root dentry */
  59         root = d_alloc_root(inode);
  60         if (!root) {
  61                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  62                 iput(inode);
  63                 return -ENOMEM;
  64         }
  65         sysfs_root.s_dentry = root;
  66         root->d_fsdata = &sysfs_root;
  67         sb->s_root = root;
  68         return 0;
  69 }
  70
  71 static int sysfs_get_sb(struct file_system_type *fs_type,
  72         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  73 {
  74         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  75 }
  76
  77 static struct file_system_type sysfs_fs_type = {
  78         .name           = "sysfs",
  79         .get_sb         = sysfs_get_sb,
  80         .kill_sb        = kill_litter_super,
  81 };
  82
  83 int __init sysfs_init(void)
  84 {
  85         int err = -ENOMEM;
  86
  87         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  88                                               sizeof(struct sysfs_dirent),
  89                                               0, 0, NULL);
  90         if (!sysfs_dir_cachep)
  91                 goto out;
  92
  93         err = register_filesystem(&sysfs_fs_type);
  94         if (!err) {
  95                 sysfs_mount = kern_mount(&sysfs_fs_type);
  96                 if (IS_ERR(sysfs_mount)) {
  97                         printk(KERN_ERR "sysfs: could not mount!\n");
  98                         err = PTR_ERR(sysfs_mount);
  99                         sysfs_mount = NULL;
 100                         unregister_filesystem(&sysfs_fs_type);
 101                         goto out_err;
 102                 }
 103         } else
 104                 goto out_err;
 105 out:
 106         return err;
 107 out_err:
 108         kmem_cache_destroy(sysfs_dir_cachep);
 109         sysfs_dir_cachep = NULL;
 110         goto out;
 111 }