Contributors: 9
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Alasdair G. Kergon |
204 |
81.93% |
4 |
28.57% |
| Christoph Hellwig |
18 |
7.23% |
2 |
14.29% |
| Kevin Corry |
10 |
4.02% |
1 |
7.14% |
| Mike Snitzer |
6 |
2.41% |
1 |
7.14% |
| Jeffle Xu |
5 |
2.01% |
1 |
7.14% |
| Jana Saout |
2 |
0.80% |
1 |
7.14% |
| Mikulas Patocka |
2 |
0.80% |
2 |
14.29% |
| Kiyoshi Ueda |
1 |
0.40% |
1 |
7.14% |
| Jens Axboe |
1 |
0.40% |
1 |
7.14% |
| Total |
249 |
|
14 |
|
/*
* Copyright (C) 2003 Jana Saout <jana@saout.de>
*
* This file is released under the GPL.
*/
#include <linux/device-mapper.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bio.h>
#define DM_MSG_PREFIX "zero"
/*
* Construct a dummy mapping that only returns zeros
*/
static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
if (argc != 0) {
ti->error = "No arguments required";
return -EINVAL;
}
/*
* Silently drop discards, avoiding -EOPNOTSUPP.
*/
ti->num_discard_bios = 1;
return 0;
}
/*
* Return zeros only on reads
*/
static int zero_map(struct dm_target *ti, struct bio *bio)
{
switch (bio_op(bio)) {
case REQ_OP_READ:
if (bio->bi_opf & REQ_RAHEAD) {
/* readahead of null bytes only wastes buffer cache */
return DM_MAPIO_KILL;
}
zero_fill_bio(bio);
break;
case REQ_OP_WRITE:
/* writes get silently dropped */
break;
default:
return DM_MAPIO_KILL;
}
bio_endio(bio);
/* accepted bio, don't make new request */
return DM_MAPIO_SUBMITTED;
}
static struct target_type zero_target = {
.name = "zero",
.version = {1, 1, 0},
.features = DM_TARGET_NOWAIT,
.module = THIS_MODULE,
.ctr = zero_ctr,
.map = zero_map,
};
static int __init dm_zero_init(void)
{
int r = dm_register_target(&zero_target);
if (r < 0)
DMERR("register failed %d", r);
return r;
}
static void __exit dm_zero_exit(void)
{
dm_unregister_target(&zero_target);
}
module_init(dm_zero_init)
module_exit(dm_zero_exit)
MODULE_AUTHOR("Jana Saout <jana@saout.de>");
MODULE_DESCRIPTION(DM_NAME " dummy target returning zeros");
MODULE_LICENSE("GPL");