Commit dba14160 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Alasdair G Kergon
Browse files

dm: store dm_target_io in bio front_pad 



Use the recently-added bio front_pad field to allocate struct dm_target_io.

Prior to this patch, dm_target_io was allocated from a mempool. For each
dm_target_io, there is exactly one bio allocated from a bioset.

This patch merges these two allocations into one allocation: we create a
bioset with front_pad equal to the size of dm_target_io so that every
bio allocated from the bioset has sizeof(struct dm_target_io) bytes
before it. We allocate a bio and use the bytes before the bio as
dm_target_io.

_tio_cache is removed and the tio_pool mempool is now only used for
request-based devices.

This idea was introduced by Kent Overstreet.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: tj@kernel.org
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Bill Pemberton <wfp5p@viridian.itc.virginia.edu>
Signed-off-by: default avatarAlasdair G Kergon <agk@redhat.com>
parent 4f81a417

drivers/md/dm.c

+49 −59
Original line number Diff line number Diff line
@@ -71,6 +71,7 @@ struct dm_target_io { 
	struct dm_io *io;

	struct dm_target *ti;

	union map_info info;

	struct bio clone;

};



/*
@@ -214,7 +215,6 @@ struct dm_md_mempools { 


#define MIN_IOS 256

static struct kmem_cache *_io_cache;

static struct kmem_cache *_tio_cache;

static struct kmem_cache *_rq_tio_cache;



/*
@@ -232,14 +232,9 @@ static int __init local_init(void) 
	if (!_io_cache)

		return r;



	/* allocate a slab for the target ios */

	_tio_cache = KMEM_CACHE(dm_target_io, 0);

	if (!_tio_cache)

		goto out_free_io_cache;



	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);

	if (!_rq_tio_cache)

		goto out_free_tio_cache;

		goto out_free_io_cache;



	_rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0);

	if (!_rq_bio_info_cache)
@@ -265,8 +260,6 @@ out_free_rq_bio_info_cache: 
	kmem_cache_destroy(_rq_bio_info_cache);

out_free_rq_tio_cache:

	kmem_cache_destroy(_rq_tio_cache);

out_free_tio_cache:

	kmem_cache_destroy(_tio_cache);

out_free_io_cache:

	kmem_cache_destroy(_io_cache);
@@ -277,7 +270,6 @@ static void local_exit(void) 
{

	kmem_cache_destroy(_rq_bio_info_cache);

	kmem_cache_destroy(_rq_tio_cache);

	kmem_cache_destroy(_tio_cache);

	kmem_cache_destroy(_io_cache);

	unregister_blkdev(_major, _name);

	dm_uevent_exit();
@@ -463,7 +455,7 @@ static void free_io(struct mapped_device *md, struct dm_io *io) 


static void free_tio(struct mapped_device *md, struct dm_target_io *tio)

{

	mempool_free(tio, md->tio_pool);

	bio_put(&tio->clone);

}



static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
@@ -682,7 +674,6 @@ static void clone_endio(struct bio *bio, int error) 
	}



	free_tio(md, tio);

	bio_put(bio);

	dec_pending(io, error);

}
@@ -1002,12 +993,12 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len) 
}

EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);



static void __map_bio(struct dm_target *ti, struct bio *clone,

		      struct dm_target_io *tio)

static void __map_bio(struct dm_target *ti, struct dm_target_io *tio)

{

	int r;

	sector_t sector;

	struct mapped_device *md;

	struct bio *clone = &tio->clone;



	clone->bi_end_io = clone_endio;

	clone->bi_private = tio;
@@ -1031,7 +1022,6 @@ static void __map_bio(struct dm_target *ti, struct bio *clone, 
		/* error the io and bail out, or requeue it if needed */

		md = tio->io->md;

		dec_pending(tio->io, r);

		bio_put(clone);

		free_tio(md, tio);

	} else if (r) {

		DMWARN("unimplemented target map return value: %d", r);
@@ -1052,14 +1042,13 @@ struct clone_info { 
/*

 * Creates a little bio that just does part of a bvec.

 */

static struct bio *split_bvec(struct bio *bio, sector_t sector,

			      unsigned short idx, unsigned int offset,

static void split_bvec(struct dm_target_io *tio, struct bio *bio,

		       sector_t sector, unsigned short idx, unsigned int offset,

		       unsigned int len, struct bio_set *bs)

{

	struct bio *clone;

	struct bio *clone = &tio->clone;

	struct bio_vec *bv = bio->bi_io_vec + idx;



	clone = bio_alloc_bioset(GFP_NOIO, 1, bs);

	*clone->bi_io_vec = *bv;



	clone->bi_sector = sector;
@@ -1076,20 +1065,18 @@ static struct bio *split_bvec(struct bio *bio, sector_t sector, 
		bio_integrity_trim(clone,

				   bio_sector_offset(bio, idx, offset), len);

	}



	return clone;

}



/*

 * Creates a bio that consists of range of complete bvecs.

 */

static struct bio *clone_bio(struct bio *bio, sector_t sector,

			     unsigned short idx, unsigned short bv_count,

			     unsigned int len, struct bio_set *bs)

static void clone_bio(struct dm_target_io *tio, struct bio *bio,

		      sector_t sector, unsigned short idx,

		      unsigned short bv_count, unsigned int len,

		      struct bio_set *bs)

{

	struct bio *clone;

	struct bio *clone = &tio->clone;



	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);

	__bio_clone(clone, bio);

	clone->bi_sector = sector;

	clone->bi_idx = idx;
@@ -1104,14 +1091,16 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector, 
			bio_integrity_trim(clone,

					   bio_sector_offset(bio, idx, 0), len);

	}



	return clone;

}



static struct dm_target_io *alloc_tio(struct clone_info *ci,

				      struct dm_target *ti)

				      struct dm_target *ti, int nr_iovecs)

{

	struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO);

	struct dm_target_io *tio;

	struct bio *clone;



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

	tio = container_of(clone, struct dm_target_io, clone);



	tio->io = ci->io;

	tio->ti = ti;
@@ -1123,8 +1112,8 @@ static struct dm_target_io *alloc_tio(struct clone_info *ci, 
static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,

				   unsigned request_nr, sector_t len)

{

	struct dm_target_io *tio = alloc_tio(ci, ti);

	struct bio *clone;

	struct dm_target_io *tio = alloc_tio(ci, ti, ci->bio->bi_max_vecs);

	struct bio *clone = &tio->clone;



	tio->info.target_request_nr = request_nr;
@@ -1133,14 +1122,14 @@ static void __issue_target_request(struct clone_info *ci, struct dm_target *ti, 
	 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush

	 * and discard, so no need for concern about wasted bvec allocations.

	 */

	clone = bio_clone_bioset(ci->bio, GFP_NOIO, ci->md->bs);



	 __bio_clone(clone, ci->bio);

	if (len) {

		clone->bi_sector = ci->sector;

		clone->bi_size = to_bytes(len);

	}



	__map_bio(ti, clone, tio);

	__map_bio(ti, tio);

}



static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
@@ -1169,14 +1158,13 @@ static int __clone_and_map_empty_flush(struct clone_info *ci) 
 */

static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)

{

	struct bio *clone, *bio = ci->bio;

	struct bio *bio = ci->bio;

	struct dm_target_io *tio;



	tio = alloc_tio(ci, ti);

	clone = clone_bio(bio, ci->sector, ci->idx,

			  bio->bi_vcnt - ci->idx, ci->sector_count,

			  ci->md->bs);

	__map_bio(ti, clone, tio);

	tio = alloc_tio(ci, ti, bio->bi_max_vecs);

	clone_bio(tio, bio, ci->sector, ci->idx, bio->bi_vcnt - ci->idx,

		  ci->sector_count, ci->md->bs);

	__map_bio(ti, tio);

	ci->sector_count = 0;

}
@@ -1214,7 +1202,7 @@ static int __clone_and_map_discard(struct clone_info *ci) 


static int __clone_and_map(struct clone_info *ci)

{

	struct bio *clone, *bio = ci->bio;

	struct bio *bio = ci->bio;

	struct dm_target *ti;

	sector_t len = 0, max;

	struct dm_target_io *tio;
@@ -1254,10 +1242,10 @@ static int __clone_and_map(struct clone_info *ci) 
			len += bv_len;

		}



		tio = alloc_tio(ci, ti);

		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,

		tio = alloc_tio(ci, ti, bio->bi_max_vecs);

		clone_bio(tio, bio, ci->sector, ci->idx, i - ci->idx, len,

			  ci->md->bs);

		__map_bio(ti, clone, tio);

		__map_bio(ti, tio);



		ci->sector += len;

		ci->sector_count -= len;
@@ -1282,12 +1270,11 @@ static int __clone_and_map(struct clone_info *ci) 


			len = min(remaining, max);



			tio = alloc_tio(ci, ti);

			clone = split_bvec(bio, ci->sector, ci->idx,

					   bv->bv_offset + offset, len,

					   ci->md->bs);

			tio = alloc_tio(ci, ti, 1);

			split_bvec(tio, bio, ci->sector, ci->idx,

				   bv->bv_offset + offset, len, ci->md->bs);



			__map_bio(ti, clone, tio);

			__map_bio(ti, tio);



			ci->sector += len;

			ci->sector_count -= len;
@@ -1955,7 +1942,7 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t) 
{

	struct dm_md_mempools *p;



	if (md->io_pool && md->tio_pool && md->bs)

	if (md->io_pool && (md->tio_pool || dm_table_get_type(t) == DM_TYPE_BIO_BASED) && md->bs)

		/* the md already has necessary mempools */

		goto out;
@@ -2732,14 +2719,16 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity) 
	if (!pools->io_pool)

		goto free_pools_and_out;



	pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?

			  mempool_create_slab_pool(MIN_IOS, _tio_cache) :

			  mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);

	pools->tio_pool = NULL;

	if (type == DM_TYPE_REQUEST_BASED) {

		pools->tio_pool = mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);

		if (!pools->tio_pool)

			goto free_io_pool_and_out;

	}



	pools->bs = (type == DM_TYPE_BIO_BASED) ?

		bioset_create(pool_size, 0) :

		bioset_create(pool_size,

			      offsetof(struct dm_target_io, clone)) :

		bioset_create(pool_size,

			      offsetof(struct dm_rq_clone_bio_info, clone));

	if (!pools->bs)
@@ -2754,6 +2743,7 @@ free_bioset_and_out: 
	bioset_free(pools->bs);



free_tio_pool_and_out:

	if (pools->tio_pool)

		mempool_destroy(pools->tio_pool);



free_io_pool_and_out:

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