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Commit cbc4e3c1 authored by Mike Snitzer's avatar Mike Snitzer
Browse files

dm: do not allocate any mempools for blk-mq request-based DM 



Do not allocate the io_pool mempool for blk-mq request-based DM
(DM_TYPE_MQ_REQUEST_BASED) in dm_alloc_rq_mempools().

Also refine __bind_mempools() to have more precise awareness of which
mempools each type of DM device uses -- avoids mempool churn when
reloading DM tables (particularly for DM_TYPE_REQUEST_BASED).

Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent 183f7802

drivers/md/dm-table.c

+2 −2
Original line number Diff line number Diff line
@@ -964,8 +964,8 @@ static int dm_table_alloc_md_mempools(struct dm_table *t, struct mapped_device * 
		return -EINVAL;

	}



	if (!t->mempools)

		return -ENOMEM;

	if (IS_ERR(t->mempools))

		return PTR_ERR(t->mempools);



	return 0;

}

drivers/md/dm.c

+38 −31
Original line number Diff line number Diff line
@@ -2323,39 +2323,52 @@ static void free_dev(struct mapped_device *md) 
	kfree(md);

}



static unsigned filter_md_type(unsigned type, struct mapped_device *md)

{

	if (type == DM_TYPE_BIO_BASED)

		return type;



	return !md->use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;

}



static void __bind_mempools(struct mapped_device *md, struct dm_table *t)

{

	struct dm_md_mempools *p = dm_table_get_md_mempools(t);



	if (md->bs) {

		/* The md already has necessary mempools. */

		if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {

	switch (filter_md_type(dm_table_get_type(t), md)) {

	case DM_TYPE_BIO_BASED:

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

			/*

			 * This bio-based md already has necessary mempools.

			 * Reload bioset because front_pad may have changed

			 * because a different table was loaded.

			 */

			bioset_free(md->bs);

			md->bs = p->bs;

			p->bs = NULL;

			goto out;

		}

		break;

	case DM_TYPE_REQUEST_BASED:

		if (md->rq_pool && md->io_pool)

			/*

		 * There's no need to reload with request-based dm

		 * because the size of front_pad doesn't change.

		 * Note for future: If you are to reload bioset,

		 * prep-ed requests in the queue may refer

		 * to bio from the old bioset, so you must walk

		 * through the queue to unprep.

			 * This request-based md already has necessary mempools.

			 */

			goto out;

		break;

	case DM_TYPE_MQ_REQUEST_BASED:

		BUG_ON(p); /* No mempools needed */

		return;

	}



	BUG_ON(!p || md->io_pool || md->rq_pool || md->bs);



	md->io_pool = p->io_pool;

	p->io_pool = NULL;

	md->rq_pool = p->rq_pool;

	p->rq_pool = NULL;

	md->bs = p->bs;

	p->bs = NULL;



out:

	/* mempool bind completed, no longer need any mempools in the table */

	dm_table_free_md_mempools(t);
@@ -2734,14 +2747,6 @@ static int dm_init_request_based_blk_mq_queue(struct mapped_device *md) 
	return err;

}



static unsigned filter_md_type(unsigned type, struct mapped_device *md)

{

	if (type == DM_TYPE_BIO_BASED)

		return type;



	return !md->use_blk_mq ? DM_TYPE_REQUEST_BASED : DM_TYPE_MQ_REQUEST_BASED;

}



/*

 * Setup the DM device's queue based on md's type

 */
@@ -3463,7 +3468,7 @@ struct dm_md_mempools *dm_alloc_bio_mempools(unsigned integrity, 


	pools = kzalloc(sizeof(*pools), GFP_KERNEL);

	if (!pools)

		return NULL;

		return ERR_PTR(-ENOMEM);



	front_pad = roundup(per_bio_data_size, __alignof__(struct dm_target_io)) +

		offsetof(struct dm_target_io, clone);
@@ -3482,24 +3487,26 @@ struct dm_md_mempools *dm_alloc_bio_mempools(unsigned integrity, 
	return pools;

out:

	dm_free_md_mempools(pools);

	return NULL;

	return ERR_PTR(-ENOMEM);

}



struct dm_md_mempools *dm_alloc_rq_mempools(struct mapped_device *md,

					    unsigned type)

{

	unsigned int pool_size = dm_get_reserved_rq_based_ios();

	unsigned int pool_size;

	struct dm_md_mempools *pools;



	if (filter_md_type(type, md) == DM_TYPE_MQ_REQUEST_BASED)

		return NULL; /* No mempools needed */



	pool_size = dm_get_reserved_rq_based_ios();

	pools = kzalloc(sizeof(*pools), GFP_KERNEL);

	if (!pools)

		return NULL;

		return ERR_PTR(-ENOMEM);



	if (filter_md_type(type, md) == DM_TYPE_REQUEST_BASED) {

	pools->rq_pool = mempool_create_slab_pool(pool_size, _rq_cache);

	if (!pools->rq_pool)

		goto out;

	}



	pools->io_pool = mempool_create_slab_pool(pool_size, _rq_tio_cache);

	if (!pools->io_pool)
@@ -3508,7 +3515,7 @@ struct dm_md_mempools *dm_alloc_rq_mempools(struct mapped_device *md, 
	return pools;

out:

	dm_free_md_mempools(pools);

	return NULL;

	return ERR_PTR(-ENOMEM);

}



void dm_free_md_mempools(struct dm_md_mempools *pools)