tmp_suning_uos_patched/drivers/md/dm-zero.c
Jens Axboe 1eff9d322a block: rename bio bi_rw to bi_opf
Since commit 63a4cc2486, bio->bi_rw contains flags in the lower
portion and the op code in the higher portions. This means that
old code that relies on manually setting bi_rw is most likely
going to be broken. Instead of letting that brokeness linger,
rename the member, to force old and out-of-tree code to break
at compile time instead of at runtime.

No intended functional changes in this commit.

Signed-off-by: Jens Axboe <axboe@fb.com>
2016-08-07 14:41:02 -06:00

88 lines
1.5 KiB
C

/*
* 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 -EIO;
}
zero_fill_bio(bio);
break;
case REQ_OP_WRITE:
/* writes get silently dropped */
break;
default:
return -EIO;
}
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},
.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");