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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: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Junichi Nomura 2014-10-03 17:27:12 -04:00 committed by Jens Axboe
parent 11dfce509e
commit d8f429e166
2 changed files with 45 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

61
block/bio.c
View File

@ -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;
bs->bvec_pool = biovec_create_pool(pool_size);
if (!bs->bvec_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

1
include/linux/bio.h
View File

@ -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);