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/*
 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
 *
 * This file is released under the GPL.
 */
 
#include "dm.h"
 
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/bio.h>
#include <linux/slab.h>
 
#define DM_MSG_PREFIX "linear"
 
/*
 * Linear: maps a linear range of a device.
 */
struct linear_c {
	struct dm_dev *dev;
	sector_t start;
};
 
/*
 * Construct a linear mapping: <dev_path> <offset>
 */
static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
	struct linear_c *lc;
	unsigned long long tmp;
 
	if (argc != 2) {
		ti->error = "Invalid argument count";
		return -EINVAL;
	}
 
	lc = kmalloc(sizeof(*lc), GFP_KERNEL);
	if (lc == NULL) {
		ti->error = "dm-linear: Cannot allocate linear context";
		return -ENOMEM;
	}
 
	if (sscanf(argv[1], "%llu", &tmp) != 1) {
		ti->error = "dm-linear: Invalid device sector";
		goto bad;
	}
	lc->start = tmp;
 
	if (dm_get_device(ti, argv[0], lc->start, ti->len,
			  dm_table_get_mode(ti->table), &lc->dev)) {
		ti->error = "dm-linear: Device lookup failed";
		goto bad;
	}
 
	ti->private = lc;
	return 0;
 
      bad:
	kfree(lc);
	return -EINVAL;
}
 
static void linear_dtr(struct dm_target *ti)
{
	struct linear_c *lc = (struct linear_c *) ti->private;
 
	dm_put_device(ti, lc->dev);
	kfree(lc);
}
 
static int linear_map(struct dm_target *ti, struct bio *bio,
		      union map_info *map_context)
{
	struct linear_c *lc = (struct linear_c *) ti->private;
 
	bio->bi_bdev = lc->dev->bdev;
	bio->bi_sector = lc->start + (bio->bi_sector - ti->begin);
 
	return DM_MAPIO_REMAPPED;
}
 
static int linear_status(struct dm_target *ti, status_type_t type,
			 char *result, unsigned int maxlen)
{
	struct linear_c *lc = (struct linear_c *) ti->private;
 
	switch (type) {
	case STATUSTYPE_INFO:
		result[0] = '\0';
		break;
 
	case STATUSTYPE_TABLE:
		snprintf(result, maxlen, "%s %llu", lc->dev->name,
				(unsigned long long)lc->start);
		break;
	}
	return 0;
}
 
static int linear_ioctl(struct dm_target *ti, struct inode *inode,
			struct file *filp, unsigned int cmd,
			unsigned long arg)
{
	struct linear_c *lc = (struct linear_c *) ti->private;
	struct block_device *bdev = lc->dev->bdev;
	struct file fake_file = {};
	struct dentry fake_dentry = {};
 
	fake_file.f_mode = lc->dev->mode;
	fake_file.f_path.dentry = &fake_dentry;
	fake_dentry.d_inode = bdev->bd_inode;
 
	return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
}
 
static struct target_type linear_target = {
	.name   = "linear",
	.version= {1, 0, 2},
	.module = THIS_MODULE,
	.ctr    = linear_ctr,
	.dtr    = linear_dtr,
	.map    = linear_map,
	.status = linear_status,
	.ioctl  = linear_ioctl,
};
 
int __init dm_linear_init(void)
{
	int r = dm_register_target(&linear_target);
 
	if (r < 0)
		DMERR("register failed %d", r);
 
	return r;
}
 
void dm_linear_exit(void)
{
	int r = dm_unregister_target(&linear_target);
 
	if (r < 0)
		DMERR("unregister failed %d", r);
}