/* * mount.c - operations for initializing and mounting sysfs. */ #define DEBUG  #include <linux/fs.h>#include <linux/mount.h>#include <linux/pagemap.h>#include <linux/init.h>#include <asm/semaphore.h> #include "sysfs.h" /* Random magic number */#define SYSFS_MAGIC 0x62656572 struct vfsmount *sysfs_mount;struct super_block * sysfs_sb = NULL;struct kmem_cache *sysfs_dir_cachep; static void sysfs_clear_inode(struct inode *inode); static const struct super_operations sysfs_ops = {	.statfs		= simple_statfs,	.drop_inode	= sysfs_delete_inode,	.clear_inode	= sysfs_clear_inode,}; static struct sysfs_dirent sysfs_root = {	.s_sibling	= LIST_HEAD_INIT(sysfs_root.s_sibling),	.s_children	= LIST_HEAD_INIT(sysfs_root.s_children),	.s_element	= NULL,	.s_type		= SYSFS_ROOT,	.s_iattr	= NULL,}; static void sysfs_clear_inode(struct inode *inode){	kfree(inode->i_private);} static int sysfs_fill_super(struct super_block *sb, void *data, int silent){	struct inode *inode;	struct dentry *root; 	sb->s_blocksize = PAGE_CACHE_SIZE;	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;	sb->s_magic = SYSFS_MAGIC;	sb->s_op = &sysfs_ops;	sb->s_time_gran = 1;	sysfs_sb = sb; 	inode = sysfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,				 &sysfs_root);	if (inode) {		inode->i_op = &sysfs_dir_inode_operations;		inode->i_fop = &sysfs_dir_operations;		/* directory inodes start off with i_nlink == 2 (for "." entry) */		inc_nlink(inode);	} else {		pr_debug("sysfs: could not get root inode\n");		return -ENOMEM;	} 	root = d_alloc_root(inode);	if (!root) {		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);		iput(inode);		return -ENOMEM;	}	root->d_fsdata = &sysfs_root;	sb->s_root = root;	return 0;} static int sysfs_get_sb(struct file_system_type *fs_type,	int flags, const char *dev_name, void *data, struct vfsmount *mnt){	return get_sb_single(fs_type, flags, data, sysfs_fill_super, mnt);} static struct file_system_type sysfs_fs_type = {	.name		= "sysfs",	.get_sb		= sysfs_get_sb,	.kill_sb	= kill_litter_super,}; int __init sysfs_init(void){	int err = -ENOMEM; 	sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",					      sizeof(struct sysfs_dirent),					      0, 0, NULL, NULL);	if (!sysfs_dir_cachep)		goto out; 	err = register_filesystem(&sysfs_fs_type);	if (!err) {		sysfs_mount = kern_mount(&sysfs_fs_type);		if (IS_ERR(sysfs_mount)) {			printk(KERN_ERR "sysfs: could not mount!\n");			err = PTR_ERR(sysfs_mount);			sysfs_mount = NULL;			unregister_filesystem(&sysfs_fs_type);			goto out_err;		}	} else		goto out_err;out:	return err;out_err:	kmem_cache_destroy(sysfs_dir_cachep);	sysfs_dir_cachep = NULL;	goto out;}