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Commit f9ab94ce authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
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dm: introduce num_flush_requests 



Introduce num_flush_requests for a target to set to say how many flush
instructions (empty barriers) it wants to receive.  These are sent by
__clone_and_map_empty_barrier with map_info->flush_request going from 0
to (num_flush_requests - 1).

Old targets without flush support won't receive any flush requests.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 27eaa149

drivers/md/dm.c

+39 −0
Original line number Diff line number Diff line
@@ -750,6 +750,40 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector, 
	return clone;

}



static void __flush_target(struct clone_info *ci, struct dm_target *ti,

			  unsigned flush_nr)

{

	struct dm_target_io *tio = alloc_tio(ci->md);

	struct bio *clone;



	tio->io = ci->io;

	tio->ti = ti;



	memset(&tio->info, 0, sizeof(tio->info));

	tio->info.flush_request = flush_nr;



	clone = bio_alloc_bioset(GFP_NOIO, 0, ci->md->bs);

	__bio_clone(clone, ci->bio);

	clone->bi_destructor = dm_bio_destructor;



	__map_bio(ti, clone, tio);

}



static int __clone_and_map_empty_barrier(struct clone_info *ci)

{

	unsigned target_nr = 0, flush_nr;

	struct dm_target *ti;



	while ((ti = dm_table_get_target(ci->map, target_nr++)))

		for (flush_nr = 0; flush_nr < ti->num_flush_requests;

		     flush_nr++)

			__flush_target(ci, ti, flush_nr);



	ci->sector_count = 0;



	return 0;

}



static int __clone_and_map(struct clone_info *ci)

{

	struct bio *clone, *bio = ci->bio;
@@ -757,6 +791,9 @@ static int __clone_and_map(struct clone_info *ci) 
	sector_t len = 0, max;

	struct dm_target_io *tio;



	if (unlikely(bio_empty_barrier(bio)))

		return __clone_and_map_empty_barrier(ci);



	ti = dm_table_find_target(ci->map, ci->sector);

	if (!dm_target_is_valid(ti))

		return -EIO;
@@ -877,6 +914,8 @@ static void __split_and_process_bio(struct mapped_device *md, struct bio *bio) 
	ci.io->md = md;

	ci.sector = bio->bi_sector;

	ci.sector_count = bio_sectors(bio);

	if (unlikely(bio_empty_barrier(bio)))

		ci.sector_count = 1;

	ci.idx = bio->bi_idx;



	start_io_acct(ci.io);

include/linux/device-mapper.h

+11 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t; 
union map_info {

	void *ptr;

	unsigned long long ll;

	unsigned flush_request;

};



/*
@@ -167,6 +168,16 @@ struct dm_target { 
	/* Always a power of 2 */

	sector_t split_io;



	/*

	 * A number of zero-length barrier requests that will be submitted

	 * to the target for the purpose of flushing cache.

	 *

	 * The request number will be placed in union map_info->flush_request.

	 * It is a responsibility of the target driver to remap these requests

	 * to the real underlying devices.

	 */

	unsigned num_flush_requests;



	/*

	 * These are automatically filled in by

	 * dm_table_get_device.