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Commit d8f429e1 authored by Junichi Nomura's avatar Junichi Nomura Committed by Jens Axboe
Browse files

block: add bioset_create_nobvec() 



Users of bio_clone_fast() do not want bios with their own bvecs.
Allocating a bvec mempool as part of the bioset intended for such users
is a waste of memory.

bioset_create_nobvec() creates a bioset that doesn't have the bvec
mempool.

Signed-off-by: default avatarJun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 11dfce50

block/bio.c

+44 −17
Original line number Diff line number Diff line
@@ -428,6 +428,9 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs) 
		front_pad = 0;

		inline_vecs = nr_iovecs;

	} else {

		/* should not use nobvec bioset for nr_iovecs > 0 */

		if (WARN_ON_ONCE(!bs->bvec_pool && nr_iovecs > 0))

			return NULL;

		/*

		 * generic_make_request() converts recursion to iteration; this

		 * means if we're running beneath it, any bios we allocate and
@@ -1900,20 +1903,9 @@ void bioset_free(struct bio_set *bs) 
}

EXPORT_SYMBOL(bioset_free);



/**

 * bioset_create  - Create a bio_set

 * @pool_size:	Number of bio and bio_vecs to cache in the mempool

 * @front_pad:	Number of bytes to allocate in front of the returned bio

 *

 * Description:

 *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller

 *    to ask for a number of bytes to be allocated in front of the bio.

 *    Front pad allocation is useful for embedding the bio inside

 *    another structure, to avoid allocating extra data to go with the bio.

 *    Note that the bio must be embedded at the END of that structure always,

 *    or things will break badly.

 */

struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)

static struct bio_set *__bioset_create(unsigned int pool_size,

				       unsigned int front_pad,

				       bool create_bvec_pool)

{

	unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);

	struct bio_set *bs;
@@ -1938,9 +1930,11 @@ struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad) 
	if (!bs->bio_pool)

		goto bad;



	if (create_bvec_pool) {

		bs->bvec_pool = biovec_create_pool(pool_size);

		if (!bs->bvec_pool)

			goto bad;

	}



	bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);

	if (!bs->rescue_workqueue)
@@ -1951,8 +1945,41 @@ bad: 
	bioset_free(bs);

	return NULL;

}



/**

 * bioset_create  - Create a bio_set

 * @pool_size:	Number of bio and bio_vecs to cache in the mempool

 * @front_pad:	Number of bytes to allocate in front of the returned bio

 *

 * Description:

 *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller

 *    to ask for a number of bytes to be allocated in front of the bio.

 *    Front pad allocation is useful for embedding the bio inside

 *    another structure, to avoid allocating extra data to go with the bio.

 *    Note that the bio must be embedded at the END of that structure always,

 *    or things will break badly.

 */

struct bio_set *bioset_create(unsigned int pool_size, unsigned int front_pad)

{

	return __bioset_create(pool_size, front_pad, true);

}

EXPORT_SYMBOL(bioset_create);



/**

 * bioset_create_nobvec  - Create a bio_set without bio_vec mempool

 * @pool_size:	Number of bio to cache in the mempool

 * @front_pad:	Number of bytes to allocate in front of the returned bio

 *

 * Description:

 *    Same functionality as bioset_create() except that mempool is not

 *    created for bio_vecs. Saving some memory for bio_clone_fast() users.

 */

struct bio_set *bioset_create_nobvec(unsigned int pool_size, unsigned int front_pad)

{

	return __bioset_create(pool_size, front_pad, false);

}

EXPORT_SYMBOL(bioset_create_nobvec);



#ifdef CONFIG_BLK_CGROUP

/**

 * bio_associate_current - associate a bio with %current

include/linux/bio.h

+1 −0
Original line number Diff line number Diff line
@@ -378,6 +378,7 @@ static inline struct bio *bio_next_split(struct bio *bio, int sectors, 
}



extern struct bio_set *bioset_create(unsigned int, unsigned int);

extern struct bio_set *bioset_create_nobvec(unsigned int, unsigned int);

extern void bioset_free(struct bio_set *);

extern mempool_t *biovec_create_pool(int pool_entries);