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 static struct sysfs_dirent sysfs_root = {
  28         .s_count        = ATOMIC_INIT(1),
  29         .s_sibling      = LIST_HEAD_INIT(sysfs_root.s_sibling),
  30         .s_children     = LIST_HEAD_INIT(sysfs_root.s_children),
  31         .s_type         = SYSFS_ROOT,
  32         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  33         .s_iattr        = NULL,
  34         .s_ino          = 1,
  35 };
  36
  37 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  38 {
  39         struct inode *inode;
  40         struct dentry *root;
  41
  42         sb->s_blocksize = PAGE_CACHE_SIZE;
  43         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  44         sb->s_magic = SYSFS_MAGIC;
  45         sb->s_op = &sysfs_ops;
  46         sb->s_time_gran = 1;
  47         sysfs_sb = sb;
  48
  49         inode = new_inode(sysfs_sb);
  50         if (!inode) {
  51                 pr_debug("sysfs: could not get root inode\n");
  52                 return -ENOMEM;
  53         }
  54
  55         sysfs_init_inode(&sysfs_root, inode);
  56
  57         inode->i_op = &sysfs_dir_inode_operations;
  58         inode->i_fop = &sysfs_dir_operations;
  59         /* directory inodes start off with i_nlink == 2 (for "." entry) */
  60         inc_nlink(inode);
  61
  62         root = d_alloc_root(inode);
  63         if (!root) {
  64                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  65                 iput(inode);
  66                 return -ENOMEM;
  67         }
  68         root->d_fsdata = &sysfs_root;
  69         sb->s_root = root;
  70         return 0;
  71 }
  72
  73 static int sysfs_get_sb(struct file_system_type *fs_type,
  74         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  75 {
  76         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  77 }
  78
  79 static struct file_system_type sysfs_fs_type = {
  80         .name           = "sysfs",
  81         .get_sb         = sysfs_get_sb,
  82         .kill_sb        = kill_litter_super,
  83 };
  84
  85 int __init sysfs_init(void)
  86 {
  87         int err = -ENOMEM;
  88
  89         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  90                                               sizeof(struct sysfs_dirent),
  91                                               0, 0, NULL, NULL);
  92         if (!sysfs_dir_cachep)
  93                 goto out;
  94
  95         err = register_filesystem(&sysfs_fs_type);
  96         if (!err) {
  97                 sysfs_mount = kern_mount(&sysfs_fs_type);
  98                 if (IS_ERR(sysfs_mount)) {
  99                         printk(KERN_ERR "sysfs: could not mount!\n");
 100                         err = PTR_ERR(sysfs_mount);
 101                         sysfs_mount = NULL;
 102                         unregister_filesystem(&sysfs_fs_type);
 103                         goto out_err;
 104                 }
 105         } else
 106                 goto out_err;
 107 out:
 108         return err;
 109 out_err:
 110         kmem_cache_destroy(sysfs_dir_cachep);
 111         sysfs_dir_cachep = NULL;
 112         goto out;
 113 }