On Fri, Oct 03 2014 at 7:55am -0400,
Junichi Nomura <j-nomura@xxxxxxxxxxxxx> wrote:
> Users of bio_clone_fast() do not need its own bvecs.
> Allocating bvec mempool for such users is waste of memory.
>
> This variant allows them to create bioset without bvec mempool.
>
> Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
> ---
> block/bio.c | 61 ++++++++++++++++++++++++++++++++++++++---------------
> include/linux/bio.h | 1 +
> 2 files changed, 45 insertions(+), 17 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 3e6331d..98c5100 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -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,
> + unsigned int create_bvec_pool)
> {
> unsigned int back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
> struct bio_set *bs;
Any reason not to use bool for create_bvec_pool?
> @@ -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, 1);
> +}
> EXPORT_SYMBOL(bioset_create);
>
> +/**
> + * bioset_nobvec_create - 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_nobvec_create(unsigned int pool_size, unsigned int front_pad)
> +{
> + return __bioset_create(pool_size, front_pad, 0);
> +}
> +EXPORT_SYMBOL(bioset_nobvec_create);
> +
> #ifdef CONFIG_BLK_CGROUP
> /**
> * bio_associate_current - associate a bio with %current
And use true and false accordingly...
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index b39e500..7d7b2a7 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -342,6 +342,7 @@ 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_nobvec_create(unsigned int, unsigned int);
> extern void bioset_free(struct bio_set *);
> extern mempool_t *biovec_create_pool(int pool_entries);
Also, I prefer the function name: bioset_create_nobvec (to keep it in
the "bioset_create" family).
Otherwise, please feel free to add to v2:
Acked-by: Mike Snitzer <snitzer@xxxxxxxxxx>
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