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 21 #include "sysfs.h" 22 23 /* Random magic number */ 24 #define SYSFS_MAGIC 0x62656572 25 26 static struct vfsmount *sysfs_mount; 27 struct super_block * sysfs_sb = NULL; 28 struct kmem_cache *sysfs_dir_cachep; 29 30 static const struct super_operations sysfs_ops = { 31 .statfs = simple_statfs, 32 .drop_inode = generic_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 inode = sysfs_get_inode(&sysfs_root); 57 if (!inode) { 58 pr_debug("sysfs: could not get root inode\n"); 59 return -ENOMEM; 60 } 61 62 /* instantiate and link root dentry */ 63 root = d_alloc_root(inode); 64 if (!root) { 65 pr_debug("%s: could not get root dentry!\n",__func__); 66 iput(inode); 67 return -ENOMEM; 68 } 69 root->d_fsdata = &sysfs_root; 70 sb->s_root = root; 71 return 0; 72 } 73 74 static int sysfs_get_sb(struct file_system_type *fs_type, 75 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 76 { 77 return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt); 78 } 79 80 static struct file_system_type sysfs_fs_type = { 81 .name = "sysfs", 82 .get_sb = sysfs_get_sb, 83 .kill_sb = kill_anon_super, 84 }; 85 86 int __init sysfs_init(void) 87 { 88 int err = -ENOMEM; 89 90 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 91 sizeof(struct sysfs_dirent), 92 0, 0, NULL); 93 if (!sysfs_dir_cachep) 94 goto out; 95 96 err = sysfs_inode_init(); 97 if (err) 98 goto out_err; 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 } 119 120 #undef sysfs_get 121 struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd) 122 { 123 return __sysfs_get(sd); 124 } 125 EXPORT_SYMBOL_GPL(sysfs_get); 126 127 #undef sysfs_put 128 void sysfs_put(struct sysfs_dirent *sd) 129 { 130 __sysfs_put(sd); 131 } 132 EXPORT_SYMBOL_GPL(sysfs_put); 133