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 const struct super_operations sysfs_ops = { 25 .statfs = simple_statfs, 26 .drop_inode = sysfs_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 .s_ino = 1, 37 }; 38 39 static void sysfs_clear_inode(struct inode *inode) 40 { 41 kfree(inode->i_private); 42 } 43 44 static int sysfs_fill_super(struct super_block *sb, void *data, int silent) 45 { 46 struct inode *inode; 47 struct dentry *root; 48 49 sb->s_blocksize = PAGE_CACHE_SIZE; 50 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 51 sb->s_magic = SYSFS_MAGIC; 52 sb->s_op = &sysfs_ops; 53 sb->s_time_gran = 1; 54 sysfs_sb = sb; 55 56 inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, 57 &sysfs_root); 58 if (inode) { 59 inode->i_op = &sysfs_dir_inode_operations; 60 inode->i_fop = &sysfs_dir_operations; 61 /* directory inodes start off with i_nlink == 2 (for "." entry) */ 62 inc_nlink(inode); 63 } else { 64 pr_debug("sysfs: could not get root inode\n"); 65 return -ENOMEM; 66 } 67 68 root = d_alloc_root(inode); 69 if (!root) { 70 pr_debug("%s: could not get root dentry!\n",__FUNCTION__); 71 iput(inode); 72 return -ENOMEM; 73 } 74 root->d_fsdata = &sysfs_root; 75 sb->s_root = root; 76 return 0; 77 } 78 79 static int sysfs_get_sb(struct file_system_type *fs_type, 80 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 81 { 82 return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt); 83 } 84 85 static struct file_system_type sysfs_fs_type = { 86 .name = "sysfs", 87 .get_sb = sysfs_get_sb, 88 .kill_sb = kill_litter_super, 89 }; 90 91 int __init sysfs_init(void) 92 { 93 int err = -ENOMEM; 94 95 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 96 sizeof(struct sysfs_dirent), 97 0, 0, NULL, NULL); 98 if (!sysfs_dir_cachep) 99 goto out; 100 101 err = register_filesystem(&sysfs_fs_type); 102 if (!err) { 103 sysfs_mount = kern_mount(&sysfs_fs_type); 104 if (IS_ERR(sysfs_mount)) { 105 printk(KERN_ERR "sysfs: could not mount!\n"); 106 err = PTR_ERR(sysfs_mount); 107 sysfs_mount = NULL; 108 unregister_filesystem(&sysfs_fs_type); 109 goto out_err; 110 } 111 } else 112 goto out_err; 113 out: 114 return err; 115 out_err: 116 kmem_cache_destroy(sysfs_dir_cachep); 117 sysfs_dir_cachep = NULL; 118 goto out; 119 } 120