fs/sysfs/mount.c

   1 /*
   2  * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
   3  *
   4  * Copyright (c) 2001-3 Patrick Mochel
   5  * Copyright (c) 2007 SUSE Linux Products GmbH
   6  * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   7  *
   8  * This file is released under the GPLv2.
   9  *
  10  * Please see Documentation/filesystems/sysfs.txt for more information.
  11  */
  12
  13 #define DEBUG
  14
  15 #include <linux/fs.h>
  16 #include <linux/mount.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20 #include <linux/magic.h>
  21 #include <linux/slab.h>
  22
  23 #include "sysfs.h"
  24
  25
  26 static struct vfsmount *sysfs_mount;
  27 struct kmem_cache *sysfs_dir_cachep;
  28
  29 static const struct super_operations sysfs_ops = {
  30         .statfs         = simple_statfs,
  31         .drop_inode     = generic_delete_inode,
  32         .delete_inode   = sysfs_delete_inode,
  33 };
  34
  35 struct sysfs_dirent sysfs_root = {
  36         .s_name         = "",
  37         .s_count        = ATOMIC_INIT(1),
  38         .s_flags        = SYSFS_DIR,
  39         .s_mode         = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
  40         .s_ino          = 1,
  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
  54         /* get root inode, initialize and unlock it */
  55         mutex_lock(&sysfs_mutex);
  56         inode = sysfs_get_inode(sb, &sysfs_root);
  57         mutex_unlock(&sysfs_mutex);
  58         if (!inode) {
  59                 pr_debug("sysfs: could not get root inode\n");
  60                 return -ENOMEM;
  61         }
  62
  63         /* instantiate and link root dentry */
  64         root = d_alloc_root(inode);
  65         if (!root) {
  66                 pr_debug("%s: could not get root dentry!\n",__func__);
  67                 iput(inode);
  68                 return -ENOMEM;
  69         }
  70         root->d_fsdata = &sysfs_root;
  71         sb->s_root = root;
  72         return 0;
  73 }
  74
  75 static int sysfs_test_super(struct super_block *sb, void *data)
  76 {
  77         struct sysfs_super_info *sb_info = sysfs_info(sb);
  78         struct sysfs_super_info *info = data;
  79         int found = 1;
  80         return found;
  81 }
  82
  83 static int sysfs_set_super(struct super_block *sb, void *data)
  84 {
  85         int error;
  86         error = set_anon_super(sb, data);
  87         if (!error)
  88                 sb->s_fs_info = data;
  89         return error;
  90 }
  91
  92 static int sysfs_get_sb(struct file_system_type *fs_type,
  93         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
  94 {
  95         struct sysfs_super_info *info;
  96         struct super_block *sb;
  97         int error;
  98
  99         error = -ENOMEM;
 100         info = kzalloc(sizeof(*info), GFP_KERNEL);
 101         if (!info)
 102                 goto out;
 103         sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
 104         if (IS_ERR(sb) || sb->s_fs_info != info)
 105                 kfree(info);
 106         if (IS_ERR(sb)) {
 107                 kfree(info);
 108                 error = PTR_ERR(sb);
 109                 goto out;
 110         }
 111         if (!sb->s_root) {
 112                 sb->s_flags = flags;
 113                 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
 114                 if (error) {
 115                         deactivate_locked_super(sb);
 116                         goto out;
 117                 }
 118                 sb->s_flags |= MS_ACTIVE;
 119         }
 120
 121         simple_set_mnt(mnt, sb);
 122         error = 0;
 123 out:
 124         return error;
 125 }
 126
 127 static void sysfs_kill_sb(struct super_block *sb)
 128 {
 129         struct sysfs_super_info *info = sysfs_info(sb);
 130
 131         kill_anon_super(sb);
 132         kfree(info);
 133 }
 134
 135 static struct file_system_type sysfs_fs_type = {
 136         .name           = "sysfs",
 137         .get_sb         = sysfs_get_sb,
 138         .kill_sb        = sysfs_kill_sb,
 139 };
 140
 141 int __init sysfs_init(void)
 142 {
 143         int err = -ENOMEM;
 144
 145         sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
 146                                               sizeof(struct sysfs_dirent),
 147                                               0, 0, NULL);
 148         if (!sysfs_dir_cachep)
 149                 goto out;
 150
 151         err = sysfs_inode_init();
 152         if (err)
 153                 goto out_err;
 154
 155         err = register_filesystem(&sysfs_fs_type);
 156         if (!err) {
 157                 sysfs_mount = kern_mount(&sysfs_fs_type);
 158                 if (IS_ERR(sysfs_mount)) {
 159                         printk(KERN_ERR "sysfs: could not mount!\n");
 160                         err = PTR_ERR(sysfs_mount);
 161                         sysfs_mount = NULL;
 162                         unregister_filesystem(&sysfs_fs_type);
 163                         goto out_err;
 164                 }
 165         } else
 166                 goto out_err;
 167 out:
 168         return err;
 169 out_err:
 170         kmem_cache_destroy(sysfs_dir_cachep);
 171         sysfs_dir_cachep = NULL;
 172         goto out;
 173 }
 174
 175 #undef sysfs_get
 176 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
 177 {
 178         return __sysfs_get(sd);
 179 }
 180 EXPORT_SYMBOL_GPL(sysfs_get);
 181
 182 #undef sysfs_put
 183 void sysfs_put(struct sysfs_dirent *sd)
 184 {
 185         __sysfs_put(sd);
 186 }
 187 EXPORT_SYMBOL_GPL(sysfs_put);