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 void sysfs_clear_inode(struct inode *inode);
  23
  24 static const struct super_operations sysfs_ops = {
  25         .statfs         = simple_statfs,
  26         .drop_inode     = sysfs_delete_inode,
  27         .clear_inode    = sysfs_clear_inode,
  28 };
  29
  30 static struct sysfs_dirent sysfs_root = {
  31         .s_count        = ATOMIC_INIT(1),
  32         .s_sibling      = LIST_HEAD_INIT(sysfs_root.s_sibling),
  33         .s_children     = LIST_HEAD_INIT(sysfs_root.s_children),
  34         .s_element      = NULL,
  35         .s_type         = SYSFS_ROOT,
  36         .s_iattr        = NULL,
  37         .s_ino          = 1,
  38 };
  39
  40 static void sysfs_clear_inode(struct inode *inode)
  41 {
  42         kfree(inode->i_private);
  43 }
  44
  45 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  46 {
  47         struct inode *inode;
  48         struct dentry *root;
  49
  50         sb->s_blocksize = PAGE_CACHE_SIZE;
  51         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  52         sb->s_magic = SYSFS_MAGIC;
  53         sb->s_op = &sysfs_ops;
  54         sb->s_time_gran = 1;
  55         sysfs_sb = sb;
  56
  57         inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  58                                  &sysfs_root);
  59         if (inode) {
  60                 inode->i_op = &sysfs_dir_inode_operations;
  61                 inode->i_fop = &sysfs_dir_operations;
  62                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  63                 inc_nlink(inode);
  64         } else {
  65                 pr_debug("sysfs: could not get root inode\n");
  66                 return -ENOMEM;
  67         }
  68
  69         root = d_alloc_root(inode);
  70         if (!root) {
  71                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  72                 iput(inode);
  73                 return -ENOMEM;
  74         }
  75         root->d_fsdata = &sysfs_root;
  76         sb->s_root = root;
  77         return 0;
  78 }
  79
  80 static int sysfs_get_sb(struct file_system_type *fs_type,
  81         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  82 {
  83         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  84 }
  85
  86 static struct file_system_type sysfs_fs_type = {
  87         .name           = "sysfs",
  88         .get_sb         = sysfs_get_sb,
  89         .kill_sb        = kill_litter_super,
  90 };
  91
  92 int __init sysfs_init(void)
  93 {
  94         int err = -ENOMEM;
  95
  96         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  97                                               sizeof(struct sysfs_dirent),
  98                                               0, 0, NULL, NULL);
  99         if (!sysfs_dir_cachep)
 100                 goto out;
 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 }