arch/s390/hypfs/inode.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-1.0+
 /*
  *    Hypervisor filesystem for Linux on s390.
  *
  *    Copyright IBM Corp. 2006, 2008
  *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
  */

 #define KMSG_COMPONENT "hypfs"
 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

 #include <linux/types.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
 #include <linux/namei.h>
 #include <linux/vfs.h>
 #include <linux/slab.h>
 #include <linux/pagemap.h>
 #include <linux/time.h>
 #include <linux/sysfs.h>
 #include <linux/init.h>
 #include <linux/kobject.h>
 #include <linux/seq_file.h>
 #include <linux/uio.h>
 #include <asm/ebcdic.h>
 #include "hypfs.h"

 #define HYPFS_MAGIC 0x687970	/* ASCII 'hyp' */
 #define TMP_SIZE 64		/* size of temporary buffers */

 static struct dentry *hypfs_create_update_file(struct dentry *dir);

 struct hypfs_sb_info {
 	kuid_t uid;			/* uid used for files and dirs */
 	kgid_t gid;			/* gid used for files and dirs */
 	struct dentry *update_file;	/* file to trigger update */
 	time64_t last_update;		/* last update, CLOCK_MONOTONIC time */
 	struct mutex lock;		/* lock to protect update process */
 };

 static const struct file_operations hypfs_file_ops;
 static struct file_system_type hypfs_type;
 static const struct super_operations hypfs_s_ops;

 /* start of list of all dentries, which have to be deleted on update */
 static struct dentry *hypfs_last_dentry;

 static void hypfs_update_update(struct super_block *sb)
 {
 	struct hypfs_sb_info *sb_info = sb->s_fs_info;
 	struct inode *inode = d_inode(sb_info->update_file);

 	sb_info->last_update = ktime_get_seconds();
 	simple_inode_init_ts(inode);
 }

 /* directory tree removal functions */

 static void hypfs_add_dentry(struct dentry *dentry)
 {
 	dentry->d_fsdata = hypfs_last_dentry;
 	hypfs_last_dentry = dentry;
 }

 static void hypfs_remove(struct dentry *dentry)
 {
 	struct dentry *parent;

 	parent = dentry->d_parent;
 	inode_lock(d_inode(parent));
 	if (simple_positive(dentry)) {
 		if (d_is_dir(dentry))
 			simple_rmdir(d_inode(parent), dentry);
 		else
 			simple_unlink(d_inode(parent), dentry);
 	}
 	d_drop(dentry);
 	dput(dentry);
 	inode_unlock(d_inode(parent));
 }

 static void hypfs_delete_tree(struct dentry *root)
 {
 	while (hypfs_last_dentry) {
 		struct dentry *next_dentry;
 		next_dentry = hypfs_last_dentry->d_fsdata;
 		hypfs_remove(hypfs_last_dentry);
 		hypfs_last_dentry = next_dentry;
 	}
 }

 static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
 {
 	struct inode *ret = new_inode(sb);

 	if (ret) {
 		struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
 		ret->i_ino = get_next_ino();
 		ret->i_mode = mode;
 		ret->i_uid = hypfs_info->uid;
 		ret->i_gid = hypfs_info->gid;
 		simple_inode_init_ts(ret);
 		if (S_ISDIR(mode))
 			set_nlink(ret, 2);
 	}
 	return ret;
 }

 static void hypfs_evict_inode(struct inode *inode)
 {
 	clear_inode(inode);
 	kfree(inode->i_private);
 }

 static int hypfs_open(struct inode *inode, struct file *filp)
 {
 	char *data = file_inode(filp)->i_private;
 	struct hypfs_sb_info *fs_info;

 	if (filp->f_mode & FMODE_WRITE) {
 		if (!(inode->i_mode & S_IWUGO))
 			return -EACCES;
 	}
 	if (filp->f_mode & FMODE_READ) {
 		if (!(inode->i_mode & S_IRUGO))
 			return -EACCES;
 	}

 	fs_info = inode->i_sb->s_fs_info;
 	if(data) {
 		mutex_lock(&fs_info->lock);
 		filp->private_data = kstrdup(data, GFP_KERNEL);
 		if (!filp->private_data) {
 			mutex_unlock(&fs_info->lock);
 			return -ENOMEM;
 		}
 		mutex_unlock(&fs_info->lock);
 	}
 	return nonseekable_open(inode, filp);
 }

 static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct file *file = iocb->ki_filp;
 	char *data = file->private_data;
 	size_t available = strlen(data);
 	loff_t pos = iocb->ki_pos;
 	size_t count;

 	if (pos < 0)
 		return -EINVAL;
 	if (pos >= available || !iov_iter_count(to))
 		return 0;
 	count = copy_to_iter(data + pos, available - pos, to);
 	if (!count)
 		return -EFAULT;
 	iocb->ki_pos = pos + count;
 	file_accessed(file);
 	return count;
 }

 static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
 {
 	int rc;
 	struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
 	struct hypfs_sb_info *fs_info = sb->s_fs_info;
 	size_t count = iov_iter_count(from);

 	/*
 	 * Currently we only allow one update per second for two reasons:
 	 * 1. diag 204 is VERY expensive
 	 * 2. If several processes do updates in parallel and then read the
 	 *    hypfs data, the likelihood of collisions is reduced, if we restrict
 	 *    the minimum update interval. A collision occurs, if during the
 	 *    data gathering of one process another process triggers an update
 	 *    If the first process wants to ensure consistent data, it has
 	 *    to restart data collection in this case.
 	 */
 	mutex_lock(&fs_info->lock);
 	if (fs_info->last_update == ktime_get_seconds()) {
 		rc = -EBUSY;
 		goto out;
 	}
 	hypfs_delete_tree(sb->s_root);
 	if (MACHINE_IS_VM)
 		rc = hypfs_vm_create_files(sb->s_root);
 	else
 		rc = hypfs_diag_create_files(sb->s_root);
 	if (rc) {
 		pr_err("Updating the hypfs tree failed\n");
 		hypfs_delete_tree(sb->s_root);
 		goto out;
 	}
 	hypfs_update_update(sb);
 	rc = count;
 	iov_iter_advance(from, count);
 out:
 	mutex_unlock(&fs_info->lock);
 	return rc;
 }

 static int hypfs_release(struct inode *inode, struct file *filp)
 {
 	kfree(filp->private_data);
 	return 0;
 }

 enum { Opt_uid, Opt_gid, };

 static const struct fs_parameter_spec hypfs_fs_parameters[] = {
 	fsparam_u32("gid", Opt_gid),
 	fsparam_u32("uid", Opt_uid),
 	{}
 };

 static int hypfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
 {
 	struct hypfs_sb_info *hypfs_info = fc->s_fs_info;
 	struct fs_parse_result result;
 	kuid_t uid;
 	kgid_t gid;
 	int opt;

 	opt = fs_parse(fc, hypfs_fs_parameters, param, &result);
 	if (opt < 0)
 		return opt;

 	switch (opt) {
 	case Opt_uid:
 		uid = make_kuid(current_user_ns(), result.uint_32);
 		if (!uid_valid(uid))
 			return invalf(fc, "Unknown uid");
 		hypfs_info->uid = uid;
 		break;
 	case Opt_gid:
 		gid = make_kgid(current_user_ns(), result.uint_32);
 		if (!gid_valid(gid))
 			return invalf(fc, "Unknown gid");
 		hypfs_info->gid = gid;
 		break;
 	}
 	return 0;
 }

 static int hypfs_show_options(struct seq_file *s, struct dentry *root)
 {
 	struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;

 	seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
 	seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
 	return 0;
 }

 static int hypfs_fill_super(struct super_block *sb, struct fs_context *fc)
 {
 	struct hypfs_sb_info *sbi = sb->s_fs_info;
 	struct inode *root_inode;
 	struct dentry *root_dentry, *update_file;
 	int rc;

 	sb->s_blocksize = PAGE_SIZE;
 	sb->s_blocksize_bits = PAGE_SHIFT;
 	sb->s_magic = HYPFS_MAGIC;
 	sb->s_op = &hypfs_s_ops;

 	root_inode = hypfs_make_inode(sb, S_IFDIR | 0755);
 	if (!root_inode)
 		return -ENOMEM;
 	root_inode->i_op = &simple_dir_inode_operations;
 	root_inode->i_fop = &simple_dir_operations;
 	sb->s_root = root_dentry = d_make_root(root_inode);
 	if (!root_dentry)
 		return -ENOMEM;
 	if (MACHINE_IS_VM)
 		rc = hypfs_vm_create_files(root_dentry);
 	else
 		rc = hypfs_diag_create_files(root_dentry);
 	if (rc)
 		return rc;
 	update_file = hypfs_create_update_file(root_dentry);
 	if (IS_ERR(update_file))
 		return PTR_ERR(update_file);
 	sbi->update_file = update_file;
 	hypfs_update_update(sb);
 	pr_info("Hypervisor filesystem mounted\n");
 	return 0;
 }

 static int hypfs_get_tree(struct fs_context *fc)
 {
 	return get_tree_single(fc, hypfs_fill_super);
 }

 static void hypfs_free_fc(struct fs_context *fc)
 {
 	kfree(fc->s_fs_info);
 }

 static const struct fs_context_operations hypfs_context_ops = {
 	.free		= hypfs_free_fc,
 	.parse_param	= hypfs_parse_param,
 	.get_tree	= hypfs_get_tree,
 };

 static int hypfs_init_fs_context(struct fs_context *fc)
 {
 	struct hypfs_sb_info *sbi;

 	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
 	if (!sbi)
 		return -ENOMEM;

 	mutex_init(&sbi->lock);
 	sbi->uid = current_uid();
 	sbi->gid = current_gid();

 	fc->s_fs_info = sbi;
 	fc->ops = &hypfs_context_ops;
 	return 0;
 }

 static void hypfs_kill_super(struct super_block *sb)
 {
 	struct hypfs_sb_info *sb_info = sb->s_fs_info;

 	if (sb->s_root)
 		hypfs_delete_tree(sb->s_root);
 	if (sb_info && sb_info->update_file)
 		hypfs_remove(sb_info->update_file);
 	kfree(sb->s_fs_info);
 	sb->s_fs_info = NULL;
 	kill_litter_super(sb);
 }

 static struct dentry *hypfs_create_file(struct dentry *parent, const char *name,
 					char *data, umode_t mode)
 {
 	struct dentry *dentry;
 	struct inode *inode;

 	inode_lock(d_inode(parent));
 	dentry = lookup_one_len(name, parent, strlen(name));
 	if (IS_ERR(dentry)) {
 		dentry = ERR_PTR(-ENOMEM);
 		goto fail;
 	}
 	inode = hypfs_make_inode(parent->d_sb, mode);
 	if (!inode) {
 		dput(dentry);
 		dentry = ERR_PTR(-ENOMEM);
 		goto fail;
 	}
 	if (S_ISREG(mode)) {
 		inode->i_fop = &hypfs_file_ops;
 		if (data)
 			inode->i_size = strlen(data);
 		else
 			inode->i_size = 0;
 	} else if (S_ISDIR(mode)) {
 		inode->i_op = &simple_dir_inode_operations;
 		inode->i_fop = &simple_dir_operations;
 		inc_nlink(d_inode(parent));
 	} else
 		BUG();
 	inode->i_private = data;
 	d_instantiate(dentry, inode);
 	dget(dentry);
 fail:
 	inode_unlock(d_inode(parent));
 	return dentry;
 }

 struct dentry *hypfs_mkdir(struct dentry *parent, const char *name)
 {
 	struct dentry *dentry;

 	dentry = hypfs_create_file(parent, name, NULL, S_IFDIR | DIR_MODE);
 	if (IS_ERR(dentry))
 		return dentry;
 	hypfs_add_dentry(dentry);
 	return dentry;
 }

 static struct dentry *hypfs_create_update_file(struct dentry *dir)
 {
 	struct dentry *dentry;

 	dentry = hypfs_create_file(dir, "update", NULL,
 				   S_IFREG | UPDATE_FILE_MODE);
 	/*
 	 * We do not put the update file on the 'delete' list with
 	 * hypfs_add_dentry(), since it should not be removed when the tree
 	 * is updated.
 	 */
 	return dentry;
 }

 struct dentry *hypfs_create_u64(struct dentry *dir,
 				const char *name, __u64 value)
 {
 	char *buffer;
 	char tmp[TMP_SIZE];
 	struct dentry *dentry;

 	snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
 	buffer = kstrdup(tmp, GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);
 	dentry =
 	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 	if (IS_ERR(dentry)) {
 		kfree(buffer);
 		return ERR_PTR(-ENOMEM);
 	}
 	hypfs_add_dentry(dentry);
 	return dentry;
 }

 struct dentry *hypfs_create_str(struct dentry *dir,
 				const char *name, char *string)
 {
 	char *buffer;
 	struct dentry *dentry;

 	buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
 	if (!buffer)
 		return ERR_PTR(-ENOMEM);
 	sprintf(buffer, "%s\n", string);
 	dentry =
 	    hypfs_create_file(dir, name, buffer, S_IFREG | REG_FILE_MODE);
 	if (IS_ERR(dentry)) {
 		kfree(buffer);
 		return ERR_PTR(-ENOMEM);
 	}
 	hypfs_add_dentry(dentry);
 	return dentry;
 }

 static const struct file_operations hypfs_file_ops = {
 	.open		= hypfs_open,
 	.release	= hypfs_release,
 	.read_iter	= hypfs_read_iter,
 	.write_iter	= hypfs_write_iter,
 };

 static struct file_system_type hypfs_type = {
 	.owner		= THIS_MODULE,
 	.name		= "s390_hypfs",
 	.init_fs_context = hypfs_init_fs_context,
 	.parameters	= hypfs_fs_parameters,
 	.kill_sb	= hypfs_kill_super
 };

 static const struct super_operations hypfs_s_ops = {
 	.statfs		= simple_statfs,
 	.evict_inode	= hypfs_evict_inode,
 	.show_options	= hypfs_show_options,
 };

 int __init __hypfs_fs_init(void)
 {
 	int rc;

 	rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
 	if (rc)
 		return rc;
 	rc = register_filesystem(&hypfs_type);
 	if (rc)
 		goto fail;
 	return 0;
 fail:
 	sysfs_remove_mount_point(hypervisor_kobj, "s390");
 	return rc;
 }
	// SPDX-License-Identifier: GPL-1.0+
	/*
	* Hypervisor filesystem for Linux on s390.
	*
	* Copyright IBM Corp. 2006, 2008
	* Author(s): Michael Holzheu <holzheu@de.ibm.com>
	*/

	#define KMSG_COMPONENT "hypfs"
	#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

	#include <linux/types.h>
	#include <linux/errno.h>
	#include <linux/fs.h>
	#include <linux/fs_context.h>
	#include <linux/fs_parser.h>
	#include <linux/namei.h>
	#include <linux/vfs.h>
	#include <linux/slab.h>
	#include <linux/pagemap.h>
	#include <linux/time.h>
	#include <linux/sysfs.h>
	#include <linux/init.h>
	#include <linux/kobject.h>
	#include <linux/seq_file.h>
	#include <linux/uio.h>
	#include <asm/ebcdic.h>
	#include "hypfs.h"

	#define HYPFS_MAGIC 0x687970 /* ASCII 'hyp' */
	#define TMP_SIZE 64 /* size of temporary buffers */

	static struct dentry hypfs_create_update_file(struct dentry dir);

	struct hypfs_sb_info {
	kuid_t uid; /* uid used for files and dirs */
	kgid_t gid; /* gid used for files and dirs */
	struct dentry update_file; / file to trigger update */
	time64_t last_update; /* last update, CLOCK_MONOTONIC time */
	struct mutex lock; /* lock to protect update process */
	};

	static const struct file_operations hypfs_file_ops;
	static struct file_system_type hypfs_type;
	static const struct super_operations hypfs_s_ops;

	/* start of list of all dentries, which have to be deleted on update */
	static struct dentry *hypfs_last_dentry;

	static void hypfs_update_update(struct super_block *sb)
	{
	struct hypfs_sb_info *sb_info = sb->s_fs_info;
	struct inode *inode = d_inode(sb_info->update_file);

	sb_info->last_update = ktime_get_seconds();
	simple_inode_init_ts(inode);
	}

	/* directory tree removal functions */

	static void hypfs_add_dentry(struct dentry *dentry)
	{
	dentry->d_fsdata = hypfs_last_dentry;
	hypfs_last_dentry = dentry;
	}

	static void hypfs_remove(struct dentry *dentry)
	{
	struct dentry *parent;

	parent = dentry->d_parent;
	inode_lock(d_inode(parent));
	if (simple_positive(dentry)) {
	if (d_is_dir(dentry))
	simple_rmdir(d_inode(parent), dentry);
	else
	simple_unlink(d_inode(parent), dentry);
	}
	d_drop(dentry);
	dput(dentry);
	inode_unlock(d_inode(parent));
	}

	static void hypfs_delete_tree(struct dentry *root)
	{
	while (hypfs_last_dentry) {
	struct dentry *next_dentry;
	next_dentry = hypfs_last_dentry->d_fsdata;
	hypfs_remove(hypfs_last_dentry);
	hypfs_last_dentry = next_dentry;
	}
	}

	static struct inode hypfs_make_inode(struct super_block sb, umode_t mode)
	{
	struct inode *ret = new_inode(sb);

	if (ret) {
	struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
	ret->i_ino = get_next_ino();
	ret->i_mode = mode;
	ret->i_uid = hypfs_info->uid;
	ret->i_gid = hypfs_info->gid;
	simple_inode_init_ts(ret);
	if (S_ISDIR(mode))
	set_nlink(ret, 2);
	}
	return ret;
	}

	static void hypfs_evict_inode(struct inode *inode)
	{
	clear_inode(inode);
	kfree(inode->i_private);
	}

	static int hypfs_open(struct inode inode, struct file filp)
	{
	char *data = file_inode(filp)->i_private;
	struct hypfs_sb_info *fs_info;

	if (filp->f_mode & FMODE_WRITE) {
	if (!(inode->i_mode & S_IWUGO))
	return -EACCES;
	}
	if (filp->f_mode & FMODE_READ) {
	if (!(inode->i_mode & S_IRUGO))
	return -EACCES;
	}

	fs_info = inode->i_sb->s_fs_info;
	if(data) {
	mutex_lock(&fs_info->lock);
	filp->private_data = kstrdup(data, GFP_KERNEL);
	if (!filp->private_data) {
	mutex_unlock(&fs_info->lock);
	return -ENOMEM;
	}
	mutex_unlock(&fs_info->lock);
	}
	return nonseekable_open(inode, filp);
	}

	static ssize_t hypfs_read_iter(struct kiocb iocb, struct iov_iter to)
	{
	struct file *file = iocb->ki_filp;
	char *data = file->private_data;
	size_t available = strlen(data);
	loff_t pos = iocb->ki_pos;
	size_t count;

	if (pos < 0)
	return -EINVAL;
	if (pos >= available \|\| !iov_iter_count(to))
	return 0;
	count = copy_to_iter(data + pos, available - pos, to);
	if (!count)
	return -EFAULT;
	iocb->ki_pos = pos + count;
	file_accessed(file);
	return count;
	}

	static ssize_t hypfs_write_iter(struct kiocb iocb, struct iov_iter from)
	{
	int rc;
	struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
	struct hypfs_sb_info *fs_info = sb->s_fs_info;
	size_t count = iov_iter_count(from);

	/*
	* Currently we only allow one update per second for two reasons:
	* 1. diag 204 is VERY expensive
	* 2. If several processes do updates in parallel and then read the
	* hypfs data, the likelihood of collisions is reduced, if we restrict
	* the minimum update interval. A collision occurs, if during the
	* data gathering of one process another process triggers an update
	* If the first process wants to ensure consistent data, it has
	* to restart data collection in this case.
	*/
	mutex_lock(&fs_info->lock);
	if (fs_info->last_update == ktime_get_seconds()) {
	rc = -EBUSY;
	goto out;
	}
	hypfs_delete_tree(sb->s_root);
	if (MACHINE_IS_VM)
	rc = hypfs_vm_create_files(sb->s_root);
	else
	rc = hypfs_diag_create_files(sb->s_root);
	if (rc) {
	pr_err("Updating the hypfs tree failed\n");
	hypfs_delete_tree(sb->s_root);
	goto out;
	}
	hypfs_update_update(sb);
	rc = count;
	iov_iter_advance(from, count);
	out:
	mutex_unlock(&fs_info->lock);
	return rc;
	}

	static int hypfs_release(struct inode inode, struct file filp)
	{
	kfree(filp->private_data);
	return 0;
	}

	enum { Opt_uid, Opt_gid, };

	static const struct fs_parameter_spec hypfs_fs_parameters[] = {
	fsparam_u32("gid", Opt_gid),
	fsparam_u32("uid", Opt_uid),
	{}
	};

	static int hypfs_parse_param(struct fs_context fc, struct fs_parameter param)
	{
	struct hypfs_sb_info *hypfs_info = fc->s_fs_info;
	struct fs_parse_result result;
	kuid_t uid;
	kgid_t gid;
	int opt;

	opt = fs_parse(fc, hypfs_fs_parameters, param, &result);
	if (opt < 0)
	return opt;

	switch (opt) {
	case Opt_uid:
	uid = make_kuid(current_user_ns(), result.uint_32);
	if (!uid_valid(uid))
	return invalf(fc, "Unknown uid");
	hypfs_info->uid = uid;
	break;
	case Opt_gid:
	gid = make_kgid(current_user_ns(), result.uint_32);
	if (!gid_valid(gid))
	return invalf(fc, "Unknown gid");
	hypfs_info->gid = gid;
	break;
	}
	return 0;
	}

	static int hypfs_show_options(struct seq_file s, struct dentry root)
	{
	struct hypfs_sb_info *hypfs_info = root->d_sb->s_fs_info;

	seq_printf(s, ",uid=%u", from_kuid_munged(&init_user_ns, hypfs_info->uid));
	seq_printf(s, ",gid=%u", from_kgid_munged(&init_user_ns, hypfs_info->gid));
	return 0;
	}

	static int hypfs_fill_super(struct super_block sb, struct fs_context fc)
	{
	struct hypfs_sb_info *sbi = sb->s_fs_info;
	struct inode *root_inode;
	struct dentry root_dentry, update_file;
	int rc;

	sb->s_blocksize = PAGE_SIZE;
	sb->s_blocksize_bits = PAGE_SHIFT;
	sb->s_magic = HYPFS_MAGIC;
	sb->s_op = &hypfs_s_ops;

	root_inode = hypfs_make_inode(sb, S_IFDIR \| 0755);
	if (!root_inode)
	return -ENOMEM;
	root_inode->i_op = &simple_dir_inode_operations;
	root_inode->i_fop = &simple_dir_operations;
	sb->s_root = root_dentry = d_make_root(root_inode);
	if (!root_dentry)
	return -ENOMEM;
	if (MACHINE_IS_VM)
	rc = hypfs_vm_create_files(root_dentry);
	else
	rc = hypfs_diag_create_files(root_dentry);
	if (rc)
	return rc;
	update_file = hypfs_create_update_file(root_dentry);
	if (IS_ERR(update_file))
	return PTR_ERR(update_file);
	sbi->update_file = update_file;
	hypfs_update_update(sb);
	pr_info("Hypervisor filesystem mounted\n");
	return 0;
	}

	static int hypfs_get_tree(struct fs_context *fc)
	{
	return get_tree_single(fc, hypfs_fill_super);
	}

	static void hypfs_free_fc(struct fs_context *fc)
	{
	kfree(fc->s_fs_info);
	}

	static const struct fs_context_operations hypfs_context_ops = {
	.free = hypfs_free_fc,
	.parse_param = hypfs_parse_param,
	.get_tree = hypfs_get_tree,
	};

	static int hypfs_init_fs_context(struct fs_context *fc)
	{
	struct hypfs_sb_info *sbi;

	sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
	if (!sbi)
	return -ENOMEM;

	mutex_init(&sbi->lock);
	sbi->uid = current_uid();
	sbi->gid = current_gid();

	fc->s_fs_info = sbi;
	fc->ops = &hypfs_context_ops;
	return 0;
	}

	static void hypfs_kill_super(struct super_block *sb)
	{
	struct hypfs_sb_info *sb_info = sb->s_fs_info;

	if (sb->s_root)
	hypfs_delete_tree(sb->s_root);
	if (sb_info && sb_info->update_file)
	hypfs_remove(sb_info->update_file);
	kfree(sb->s_fs_info);
	sb->s_fs_info = NULL;
	kill_litter_super(sb);
	}

	static struct dentry hypfs_create_file(struct dentry parent, const char *name,
	char *data, umode_t mode)
	{
	struct dentry *dentry;
	struct inode *inode;

	inode_lock(d_inode(parent));
	dentry = lookup_one_len(name, parent, strlen(name));
	if (IS_ERR(dentry)) {
	dentry = ERR_PTR(-ENOMEM);
	goto fail;
	}
	inode = hypfs_make_inode(parent->d_sb, mode);
	if (!inode) {
	dput(dentry);
	dentry = ERR_PTR(-ENOMEM);
	goto fail;
	}
	if (S_ISREG(mode)) {
	inode->i_fop = &hypfs_file_ops;
	if (data)
	inode->i_size = strlen(data);
	else
	inode->i_size = 0;
	} else if (S_ISDIR(mode)) {
	inode->i_op = &simple_dir_inode_operations;
	inode->i_fop = &simple_dir_operations;
	inc_nlink(d_inode(parent));
	} else
	BUG();
	inode->i_private = data;
	d_instantiate(dentry, inode);
	dget(dentry);
	fail:
	inode_unlock(d_inode(parent));
	return dentry;
	}

	struct dentry hypfs_mkdir(struct dentry parent, const char *name)
	{
	struct dentry *dentry;

	dentry = hypfs_create_file(parent, name, NULL, S_IFDIR \| DIR_MODE);
	if (IS_ERR(dentry))
	return dentry;
	hypfs_add_dentry(dentry);
	return dentry;
	}

	static struct dentry hypfs_create_update_file(struct dentry dir)
	{
	struct dentry *dentry;

	dentry = hypfs_create_file(dir, "update", NULL,
	S_IFREG \| UPDATE_FILE_MODE);
	/*
	* We do not put the update file on the 'delete' list with
	* hypfs_add_dentry(), since it should not be removed when the tree
	* is updated.
	*/
	return dentry;
	}

	struct dentry hypfs_create_u64(struct dentry dir,
	const char *name, __u64 value)
	{
	char *buffer;
	char tmp[TMP_SIZE];
	struct dentry *dentry;

	snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
	buffer = kstrdup(tmp, GFP_KERNEL);
	if (!buffer)
	return ERR_PTR(-ENOMEM);
	dentry =
	hypfs_create_file(dir, name, buffer, S_IFREG \| REG_FILE_MODE);
	if (IS_ERR(dentry)) {
	kfree(buffer);
	return ERR_PTR(-ENOMEM);
	}
	hypfs_add_dentry(dentry);
	return dentry;
	}

	struct dentry hypfs_create_str(struct dentry dir,
	const char name, char string)
	{
	char *buffer;
	struct dentry *dentry;

	buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
	if (!buffer)
	return ERR_PTR(-ENOMEM);
	sprintf(buffer, "%s\n", string);
	dentry =
	hypfs_create_file(dir, name, buffer, S_IFREG \| REG_FILE_MODE);
	if (IS_ERR(dentry)) {
	kfree(buffer);
	return ERR_PTR(-ENOMEM);
	}
	hypfs_add_dentry(dentry);
	return dentry;
	}

	static const struct file_operations hypfs_file_ops = {
	.open = hypfs_open,
	.release = hypfs_release,
	.read_iter = hypfs_read_iter,
	.write_iter = hypfs_write_iter,
	};

	static struct file_system_type hypfs_type = {
	.owner = THIS_MODULE,
	.name = "s390_hypfs",
	.init_fs_context = hypfs_init_fs_context,
	.parameters = hypfs_fs_parameters,
	.kill_sb = hypfs_kill_super
	};

	static const struct super_operations hypfs_s_ops = {
	.statfs = simple_statfs,
	.evict_inode = hypfs_evict_inode,
	.show_options = hypfs_show_options,
	};

	int __init __hypfs_fs_init(void)
	{
	int rc;

	rc = sysfs_create_mount_point(hypervisor_kobj, "s390");
	if (rc)
	return rc;
	rc = register_filesystem(&hypfs_type);
	if (rc)
	goto fail;
	return 0;
	fail:
	sysfs_remove_mount_point(hypervisor_kobj, "s390");
	return rc;
	}