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 }; 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 } 119