From: Mikulas Patocka 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. This idea was introduced by Kent Overstreet. Signed-off-by: Mikulas Patocka Cc: Kent Overstreet Cc: Jens Axboe Cc: tj@kernel.org Cc: Vivek Goyal Cc: Bill Pemberton Signed-off-by: Alasdair G Kergon --- drivers/md/dm.c | 81 ++++++++++++++++++++++++++------------------------------ 1 file changed, 39 insertions(+), 42 deletions(-) Index: linux/drivers/md/dm.c =================================================================== --- linux.orig/drivers/md/dm.c +++ linux/drivers/md/dm.c @@ -71,6 +71,7 @@ struct dm_target_io { struct dm_io *io; struct dm_target *ti; union map_info info; + struct bio clone; }; /* @@ -463,7 +464,7 @@ static void free_io(struct mapped_device 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 +683,6 @@ static void clone_endio(struct bio *bio, } free_tio(md, tio); - bio_put(bio); dec_pending(io, error); } @@ -1002,12 +1002,12 @@ int dm_set_target_max_io_len(struct dm_t } 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 +1031,6 @@ static void __map_bio(struct dm_target * /* 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 +1051,13 @@ 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, - unsigned int len, struct bio_set *bs) +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 +1074,18 @@ static struct bio *split_bvec(struct bio 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 +1100,16 @@ static struct bio *clone_bio(struct bio 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 +1121,8 @@ static struct dm_target_io *alloc_tio(st 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 +1131,14 @@ static void __issue_target_request(struc * 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 +1167,13 @@ static int __clone_and_map_empty_flush(s */ 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 +1211,7 @@ static int __clone_and_map_discard(struc 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 +1251,10 @@ static int __clone_and_map(struct clone_ len += bv_len; } - tio = alloc_tio(ci, ti); - clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len, - 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, i - ci->idx, len, + ci->md->bs); + __map_bio(ti, tio); ci->sector += len; ci->sector_count -= len; @@ -1282,12 +1279,11 @@ static int __clone_and_map(struct clone_ 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; @@ -2739,7 +2735,8 @@ struct dm_md_mempools *dm_alloc_md_mempo 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)