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dm: remove unused 'num_write_bios' target interface 

No DM target provides num_write_bios and none has since dm-cache's
brief use in 2013.

Having the possibility of num_write_bios > 1 complicates bio
allocation.  So remove the interface and assume there is only one bio
needed.

If a target ever needs more, it must provide a suitable bioset and
allocate itself based on its particular needs.

Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
NeilBrown 2017-11-22 14:25:18 +11:00 committed by Mike Snitzer
parent 18a25da843
commit f31c21e436
2 changed files with 10 additions and 35 deletions
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30
drivers/md/dm.c
View File

@ -1319,32 +1319,22 @@ static int __send_empty_flush(struct clone_info *ci)
}
static int __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
sector_t sector, unsigned *len)
sector_t sector, unsigned *len)
{
struct bio *bio = ci->bio;
struct dm_target_io *tio;
unsigned target_bio_nr;
unsigned num_target_bios = 1;
int r = 0;
int r;
/*
* Does the target want to receive duplicate copies of the bio?
*/
if (bio_data_dir(bio) == WRITE && ti->num_write_bios)
num_target_bios = ti->num_write_bios(ti, bio);
for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
tio = alloc_tio(ci, ti, target_bio_nr);
tio->len_ptr = len;
r = clone_bio(tio, bio, sector, *len);
if (r < 0) {
free_tio(tio);
break;
}
__map_bio(tio);
tio = alloc_tio(ci, ti, 0);
tio->len_ptr = len;
r = clone_bio(tio, bio, sector, *len);
if (r < 0) {
free_tio(tio);
return r;
}
__map_bio(tio);
return r;
return 0;
}
typedef unsigned (*get_num_bios_fn)(struct dm_target *ti);

15
include/linux/device-mapper.h
View File

@ -220,14 +220,6 @@ struct target_type {
#define DM_TARGET_WILDCARD 0x00000008
#define dm_target_is_wildcard(type) ((type)->features & DM_TARGET_WILDCARD)
/*
* Some targets need to be sent the same WRITE bio severals times so
* that they can send copies of it to different devices. This function
* examines any supplied bio and returns the number of copies of it the
* target requires.
*/
typedef unsigned (*dm_num_write_bios_fn) (struct dm_target *ti, struct bio *bio);
/*
* A target implements own bio data integrity.
*/
@ -291,13 +283,6 @@ struct dm_target {
*/
unsigned per_io_data_size;
/*
* If defined, this function is called to find out how many
* duplicate bios should be sent to the target when writing
* data.
*/
dm_num_write_bios_fn num_write_bios;
/* target specific data */
void *private;