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   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 const struct super_operations sysfs_ops = {
  22         .statfs         = simple_statfs,
  23         .drop_inode     = generic_delete_inode,
  24 };
  25
  26 struct sysfs_dirent sysfs_root = {
  27         .s_count        = ATOMIC_INIT(1),
  28         .s_flags        = SYSFS_ROOT,
  29         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  30         .s_ino          = 1,
  31 };
  32
  33 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  34 {
  35         struct inode *inode;
  36         struct dentry *root;
  37
  38         sb->s_blocksize = PAGE_CACHE_SIZE;
  39         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  40         sb->s_magic = SYSFS_MAGIC;
  41         sb->s_op = &sysfs_ops;
  42         sb->s_time_gran = 1;
  43         sysfs_sb = sb;
  44
  45         /* get root inode, initialize and unlock it */
  46         inode = sysfs_get_inode(&sysfs_root);
  47         if (!inode) {
  48                 pr_debug("sysfs: could not get root inode\n");
  49                 return -ENOMEM;
  50         }
  51
  52         inode->i_op = &sysfs_dir_inode_operations;
  53         inode->i_fop = &sysfs_dir_operations;
  54         inc_nlink(inode); /* directory, account for "." */
  55         unlock_new_inode(inode);
  56
  57         /* instantiate and link root dentry */
  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         sysfs_root.s_dentry = root;
  65         root->d_fsdata = &sysfs_root;
  66         sb->s_root = root;
  67         return 0;
  68 }
  69
  70 static int sysfs_get_sb(struct file_system_type *fs_type,
  71         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  72 {
  73         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  74 }
  75
  76 static struct file_system_type sysfs_fs_type = {
  77         .name           = "sysfs",
  78         .get_sb         = sysfs_get_sb,
  79         .kill_sb        = kill_litter_super,
  80 };
  81
  82 int __init sysfs_init(void)
  83 {
  84         int err = -ENOMEM;
  85
  86         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  87                                               sizeof(struct sysfs_dirent),
  88                                               0, 0, NULL);
  89         if (!sysfs_dir_cachep)
  90                 goto out;
  91
  92         err = register_filesystem(&sysfs_fs_type);
  93         if (!err) {
  94                 sysfs_mount = kern_mount(&sysfs_fs_type);
  95                 if (IS_ERR(sysfs_mount)) {
  96                         printk(KERN_ERR "sysfs: could not mount!\n");
  97                         err = PTR_ERR(sysfs_mount);
  98                         sysfs_mount = NULL;
  99                         unregister_filesystem(&sysfs_fs_type);
 100                         goto out_err;
 101                 }
 102         } else
 103                 goto out_err;
 104 out:
 105         return err;
 106 out_err:
 107         kmem_cache_destroy(sysfs_dir_cachep);
 108         sysfs_dir_cachep = NULL;
 109         goto out;
 110 }