path: root/fs/nilfs2/ioctl.c

/*
 * ioctl.c - NILFS ioctl operations.
 *
 * Copyright (C) 2007, 2008 Nippon Telegraph and Telephone Corporation.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * Written by Koji Sato <koji@osrg.net>.
 */

#include <linux/fs.h>
#include <linux/wait.h>
#include <linux/slab.h>
#include <linux/capability.h>	/* capable() */
#include <linux/uaccess.h>	/* copy_from_user(), copy_to_user() */
#include <linux/vmalloc.h>
#include <linux/compat.h>	/* compat_ptr() */
#include <linux/mount.h>	/* mnt_want_write_file(), mnt_drop_write_file() */
#include <linux/buffer_head.h>
#include <linux/nilfs2_fs.h>
#include "nilfs.h"
#include "segment.h"
#include "bmap.h"
#include "cpfile.h"
#include "sufile.h"
#include "dat.h"

/**
 * nilfs_ioctl_wrap_copy - wrapping function of get/set metadata info
 * @nilfs: nilfs object
 * @argv: vector of arguments from userspace
 * @dir: set of direction flags
 * @dofunc: concrete function of get/set metadata info
 *
 * Description: nilfs_ioctl_wrap_copy() gets/sets metadata info by means of
 * calling dofunc() function on the basis of @argv argument.
 *
 * Return Value: On success, 0 is returned and requested metadata info
 * is copied into userspace. On error, one of the following
 * negative error codes is returned.
 *
 * %-EINVAL - Invalid arguments from userspace.
 *
 * %-ENOMEM - Insufficient amount of memory available.
 *
 * %-EFAULT - Failure during execution of requested operation.
 */
static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
				 struct nilfs_argv *argv, int dir,
				 ssize_t (*dofunc)(struct the_nilfs *,
						   __u64 *, int,
						   void *, size_t, size_t))
{
	void *buf;
	void __user *base = (void __user *)(unsigned long)argv->v_base;
	size_t maxmembs, total, n;
	ssize_t nr;
	int ret, i;
	__u64 pos, ppos;

	if (argv->v_nmembs == 0)
		return 0;

	if (argv->v_size > PAGE_SIZE)
		return -EINVAL;

	/*
	 * Reject pairs of a start item position (argv->v_index) and a
	 * total count (argv->v_nmembs) which leads position 'pos' to
	 * overflow by the increment at the end of the loop.
	 */
	if (argv->v_index > ~(__u64)0 - argv->v_nmembs)
		return -EINVAL;

	buf = (void *)__get_free_pages(GFP_NOFS, 0);
	if (unlikely(!buf))
		return -ENOMEM;
	maxmembs = PAGE_SIZE / argv->v_size;

	ret = 0;
	total = 0;
	pos = argv->v_index;
	for (i = 0; i < argv->v_nmembs; i += n) {
		n = (argv->v_nmembs - i < maxmembs) ?
			argv->v_nmembs - i : maxmembs;
		if ((dir & _IOC_WRITE) &&
		    copy_from_user(buf, base + argv->v_size * i,
				   argv->v_size * n)) {
			ret = -EFAULT;
			break;
		}