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 22 #include "sysfs.h" 23 24 25 static struct vfsmount *sysfs_mount; 26 struct super_block * sysfs_sb = NULL; 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 sysfs_sb = sb; 54 55 /* get root inode, initialize and unlock it */ 56 mutex_lock(&sysfs_mutex); 57 inode = sysfs_get_inode(&sysfs_root); 58 mutex_unlock(&sysfs_mutex); 59 if (!inode) { 60 pr_debug("sysfs: could not get root inode\n"); 61 return -ENOMEM; 62 } 63 64 /* instantiate and link root dentry */ 65 root = d_alloc_root(inode); 66 if (!root) { 67 pr_debug("%s: could not get root dentry!\n",__func__); 68 iput(inode); 69 return -ENOMEM; 70 } 71 root->d_fsdata = &sysfs_root; 72 sb->s_root = root; 73 return 0; 74 } 75 76 static int sysfs_get_sb(struct file_system_type *fs_type, 77 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 78 { 79 return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt); 80 } 81 82 static struct file_system_type sysfs_fs_type = { 83 .name = "sysfs", 84 .get_sb = sysfs_get_sb, 85 .kill_sb = kill_anon_super, 86 }; 87 88 int __init sysfs_init(void) 89 { 90 int err = -ENOMEM; 91 92 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 93 sizeof(struct sysfs_dirent), 94 0, 0, NULL); 95 if (!sysfs_dir_cachep) 96 goto out; 97 98 err = sysfs_inode_init(); 99 if (err) 100 goto out_err; 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 } 121 122 #undef sysfs_get 123 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) 124 { 125 return __sysfs_get(sd); 126 } 127 EXPORT_SYMBOL_GPL(sysfs_get); 128 129 #undef sysfs_put 130 void sysfs_put(struct sysfs_dirent *sd) 131 { 132 __sysfs_put(sd); 133 } 134 EXPORT_SYMBOL_GPL(sysfs_put); 135