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 const struct super_operations sysfs_ops = { 23 .statfs = simple_statfs, 24 .drop_inode = sysfs_delete_inode, 25 }; 26 27 struct sysfs_dirent sysfs_root = { 28 .s_count = ATOMIC_INIT(1), 29 .s_flags = SYSFS_ROOT, 30 .s_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, 31 .s_ino = 1, 32 }; 33 34 static int sysfs_fill_super(struct super_block *sb, void *data, int silent) 35 { 36 struct inode *inode; 37 struct dentry *root; 38 39 sb->s_blocksize = PAGE_CACHE_SIZE; 40 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 41 sb->s_magic = SYSFS_MAGIC; 42 sb->s_op = &sysfs_ops; 43 sb->s_time_gran = 1; 44 sysfs_sb = sb; 45 46 inode = new_inode(sysfs_sb); 47 if (!inode) { 48 pr_debug("sysfs: could not get root inode\n"); 49 return -ENOMEM; 50 } 51 52 sysfs_init_inode(&sysfs_root, inode); 53 54 inode->i_op = &sysfs_dir_inode_operations; 55 inode->i_fop = &sysfs_dir_operations; 56 /* directory inodes start off with i_nlink == 2 (for "." entry) */ 57 inc_nlink(inode); 58 59 root = d_alloc_root(inode); 60 if (!root) { 61 pr_debug("%s: could not get root dentry!\n",__FUNCTION__); 62 iput(inode); 63 return -ENOMEM; 64 } 65 sysfs_root.s_dentry = root; 66 root->d_fsdata = &sysfs_root; 67 sb->s_root = root; 68 return 0; 69 } 70 71 static int sysfs_get_sb(struct file_system_type *fs_type, 72 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 73 { 74 return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt); 75 } 76 77 static struct file_system_type sysfs_fs_type = { 78 .name = "sysfs", 79 .get_sb = sysfs_get_sb, 80 .kill_sb = kill_litter_super, 81 }; 82 83 int __init sysfs_init(void) 84 { 85 int err = -ENOMEM; 86 87 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache", 88 sizeof(struct sysfs_dirent), 89 0, 0, NULL, NULL); 90 if (!sysfs_dir_cachep) 91 goto out; 92 93 err = register_filesystem(&sysfs_fs_type); 94 if (!err) { 95 sysfs_mount = kern_mount(&sysfs_fs_type); 96 if (IS_ERR(sysfs_mount)) { 97 printk(KERN_ERR "sysfs: could not mount!\n"); 98 err = PTR_ERR(sysfs_mount); 99 sysfs_mount = NULL; 100 unregister_filesystem(&sysfs_fs_type); 101 goto out_err; 102 } 103 } else 104 goto out_err; 105 out: 106 return err; 107 out_err: 108 kmem_cache_destroy(sysfs_dir_cachep); 109 sysfs_dir_cachep = NULL; 110 goto out; 111 } 112