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Commit 94818742 authored by Kent Overstreet's avatar Kent Overstreet Committed by Jens Axboe
Browse files

dm: Use bioset's front_pad for dm_rq_clone_bio_info 



Previously, dm_rq_clone_bio_info needed to be freed by the bio's
destructor to avoid a memory leak in the blk_rq_prep_clone() error path.
This gets rid of a memory allocation and means we can kill
dm_rq_bio_destructor.

The _rq_bio_info_cache kmem cache is unused now and needs to be deleted,
but due to the way io_pool is used and overloaded this looks not quite
trivial so I'm leaving it for a later patch.

v6: Fix comment on struct dm_rq_clone_bio_info, per Tejun

Signed-off-by: default avatarKent Overstreet <koverstreet@google.com>
CC: Alasdair Kergon <agk@redhat.com>
Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 1e2a410f

drivers/md/dm.c

+18 −28
Original line number Diff line number Diff line
@@ -86,12 +86,17 @@ struct dm_rq_target_io { 
};



/*

 * For request-based dm.

 * One of these is allocated per bio.

 * For request-based dm - the bio clones we allocate are embedded in these

 * structs.

 *

 * We allocate these with bio_alloc_bioset, using the front_pad parameter when

 * the bioset is created - this means the bio has to come at the end of the

 * struct.

 */

struct dm_rq_clone_bio_info {

	struct bio *orig;

	struct dm_rq_target_io *tio;

	struct bio clone;

};



union map_info *dm_get_mapinfo(struct bio *bio)
@@ -211,6 +216,11 @@ struct dm_md_mempools { 
static struct kmem_cache *_io_cache;

static struct kmem_cache *_tio_cache;

static struct kmem_cache *_rq_tio_cache;



/*

 * Unused now, and needs to be deleted. But since io_pool is overloaded and it's

 * still used for _io_cache, I'm leaving this for a later cleanup

 */

static struct kmem_cache *_rq_bio_info_cache;



static int __init local_init(void)
@@ -467,16 +477,6 @@ static void free_rq_tio(struct dm_rq_target_io *tio) 
	mempool_free(tio, tio->md->tio_pool);

}



static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)

{

	return mempool_alloc(md->io_pool, GFP_ATOMIC);

}



static void free_bio_info(struct dm_rq_clone_bio_info *info)

{

	mempool_free(info, info->tio->md->io_pool);

}



static int md_in_flight(struct mapped_device *md)

{

	return atomic_read(&md->pending[READ]) +
@@ -1460,30 +1460,17 @@ void dm_dispatch_request(struct request *rq) 
}

EXPORT_SYMBOL_GPL(dm_dispatch_request);



static void dm_rq_bio_destructor(struct bio *bio)

{

	struct dm_rq_clone_bio_info *info = bio->bi_private;

	struct mapped_device *md = info->tio->md;



	free_bio_info(info);

	bio_free(bio, md->bs);

}



static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,

				 void *data)

{

	struct dm_rq_target_io *tio = data;

	struct mapped_device *md = tio->md;

	struct dm_rq_clone_bio_info *info = alloc_bio_info(md);



	if (!info)

		return -ENOMEM;

	struct dm_rq_clone_bio_info *info =

		container_of(bio, struct dm_rq_clone_bio_info, clone);



	info->orig = bio_orig;

	info->tio = tio;

	bio->bi_end_io = end_clone_bio;

	bio->bi_private = info;

	bio->bi_destructor = dm_rq_bio_destructor;



	return 0;

}
@@ -2718,7 +2705,10 @@ struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity) 
	if (!pools->tio_pool)

		goto free_io_pool_and_out;



	pools->bs = bioset_create(pool_size, 0);

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

		bioset_create(pool_size, 0) :

		bioset_create(pool_size,

			      offsetof(struct dm_rq_clone_bio_info, clone));

	if (!pools->bs)

		goto free_tio_pool_and_out;