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lvm2/driver/device-mapper/dm-linear.c

165 lines
3.6 KiB
C

/*
* dm-linear.c
*
* Copyright (C) 2001 Sistina Software
*
* This software 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, or (at
* your option) any later version.
*
* This software 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 GNU CC; see the file COPYING. If not, write to
* the Free Software Foundation, 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/device-mapper.h>
#include "dm.h"
/*
* linear: maps a linear range of a device.
*/
struct linear_c {
kdev_t rdev;
long delta; /* FIXME: we need a signed offset type */
struct block_device *bdev;
};
/*
* construct a linear mapping.
* <dev_path> <offset>
*/
static int linear_ctr(struct dm_table *t, offset_t b, offset_t l,
struct text_region *args, void **result,
dm_error_fn fn, void *private)
{
struct linear_c *lc;
unsigned int start;
char path[256];
struct text_region word;
struct block_device *bdev;
int rv = 0;
int hardsect_size;
if (!dm_get_word(args, &word)) {
fn("couldn't get device path", private);
return -EINVAL;
}
dm_txt_copy(path, sizeof(path) - 1, &word);
bdev = dm_blkdev_get(path);
if (IS_ERR(bdev)) {
switch (PTR_ERR(bdev)) {
case -ENOTBLK:
fn("not a block device", private);
break;
case -EACCES:
fn("nodev mount option", private);
break;
case -ENOENT:
default:
fn("no such device", private);
}
return PTR_ERR(bdev);
}
if (!dm_get_number(args, &start)) {
fn("destination start not given", private);
rv = -EINVAL;
goto out_bdev_put;
}
if (!(lc = kmalloc(sizeof(lc), GFP_KERNEL))) {
fn("couldn't allocate memory for linear context\n", private);
rv = -ENOMEM;
goto out_bdev_put;
}
lc->rdev = to_kdev_t(bdev->bd_dev);
lc->bdev = bdev;
lc->delta = (int) start - (int) b;
hardsect_size = get_hardsect_size(lc->rdev);
if (t->hardsect_size > hardsect_size);
t->hardsect_size = hardsect_size;
*result = lc;
return 0;
out_bdev_put:
dm_blkdev_put(bdev);
return rv;
}
static void linear_dtr(struct dm_table *t, void *c)
{
struct linear_c *lc = (struct linear_c *) c;
dm_blkdev_put(lc->bdev);
kfree(c);
}
static int linear_map(struct buffer_head *bh, int rw, void *context)
{
struct linear_c *lc = (struct linear_c *) context;
bh->b_rdev = lc->rdev;
bh->b_rsector = bh->b_rsector + lc->delta;
return 1;
}
static struct target_type linear_target = {
name: "linear",
module: THIS_MODULE,
ctr: linear_ctr,
dtr: linear_dtr,
map: linear_map,
flags: TF_BMAP,
};
static int __init linear_init(void)
{
int rv;
rv = dm_register_target(&linear_target);
if (rv < 0) {
printk(KERN_ERR "Device mapper: Linear: register failed %d\n", rv);
}
return rv;
}
static void __exit linear_exit(void)
{
int rv;
rv = dm_unregister_target(&linear_target);
if (rv < 0) {
printk(KERN_ERR "Device mapper: Linear: unregister failed %d\n", rv);
}
}
module_init(linear_init);
module_exit(linear_exit);
MODULE_AUTHOR("Joe Thornber <thornber@uk.sistina.com>");
MODULE_DESCRIPTION("Device Mapper: Linear mapping");
#ifdef MODULE_LICENSE
MODULE_LICENSE("GPL");
#endif