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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 #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 struct super_operations sysfs_ops = {
  25         .statfs         = simple_statfs,
  26         .drop_inode     = generic_delete_inode,
  27         .clear_inode    = sysfs_clear_inode,
  28 };
  29
  30 static struct sysfs_dirent sysfs_root = {
  31         .s_sibling      = LIST_HEAD_INIT(sysfs_root.s_sibling),
  32         .s_children     = LIST_HEAD_INIT(sysfs_root.s_children),
  33         .s_element      = NULL,
  34         .s_type         = SYSFS_ROOT,
  35         .s_iattr        = NULL,
  36 };
  37
  38 static void sysfs_clear_inode(struct inode *inode)
  39 {
  40         kfree(inode->i_private);
  41 }
  42
  43 static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
  44 {
  45         struct inode *inode;
  46         struct dentry *root;
  47
  48         sb->s_blocksize = PAGE_CACHE_SIZE;
  49         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
  50         sb->s_magic = SYSFS_MAGIC;
  51         sb->s_op = &sysfs_ops;
  52         sb->s_time_gran = 1;
  53         sysfs_sb = sb;
  54
  55         inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  56                                  &sysfs_root);
  57         if (inode) {
  58                 inode->i_op = &sysfs_dir_inode_operations;
  59                 inode->i_fop = &sysfs_dir_operations;
  60                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
  61                 inc_nlink(inode);
  62         } else {
  63                 pr_debug("sysfs: could not get root inode\n");
  64                 return -ENOMEM;
  65         }
  66
  67         root = d_alloc_root(inode);
  68         if (!root) {
  69                 pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
  70                 iput(inode);
  71                 return -ENOMEM;
  72         }
  73         root->d_fsdata = &sysfs_root;
  74         sb->s_root = root;
  75         return 0;
  76 }
  77
  78 static int sysfs_get_sb(struct file_system_type *fs_type,
  79         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  80 {
  81         return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);
  82 }
  83
  84 static struct file_system_type sysfs_fs_type = {
  85         .name           = "sysfs",
  86         .get_sb         = sysfs_get_sb,
  87         .kill_sb        = kill_litter_super,
  88 };
  89
  90 int __init sysfs_init(void)
  91 {
  92         int err = -ENOMEM;
  93
  94         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
  95                                               sizeof(struct sysfs_dirent),
  96                                               0, 0, NULL, NULL);
  97         if (!sysfs_dir_cachep)
  98                 goto out;
  99
 100         err = register_filesystem(&sysfs_fs_type);
 101         if (!err) {
 102                 sysfs_mount = kern_mount(&sysfs_fs_type);
 103                 if (IS_ERR(sysfs_mount)) {
 104                         printk(KERN_ERR "sysfs: could not mount!\n");
 105                         err = PTR_ERR(sysfs_mount);
 106                         sysfs_mount = NULL;
 107                         unregister_filesystem(&sysfs_fs_type);
 108                         goto out_err;
 109                 }
 110         } else
 111                 goto out_err;
 112 out:
 113         return err;
 114 out_err:
 115         kmem_cache_destroy(sysfs_dir_cachep);
 116         sysfs_dir_cachep = NULL;
 117         goto out;
 118 }