Re: [PATCH V3 3/6] block: don't allocate inline bvecs if this bioset needn't bvecs

Pavel Begunkov
2021-01-11T04:45:57Z

On 11/01/2021 03:05, Ming Lei wrote:
> The inline bvecs won't be used if user needn't bvecs by not passing
> BIOSET_NEED_BVECS, so don't allocate bvecs in this situation.
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>

Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Tested-by: Pavel Begunkov <asml.silence@gmail.com>

> ---
> block/bio.c | 7 +++++--
> include/linux/bio.h | 1 +
> 2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index cfa0e9db30e0..496aa5938f79 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -89,8 +89,7 @@ static struct bio_slab *create_bio_slab(unsigned int size)
>
> static inline unsigned int bs_bio_slab_size(struct bio_set *bs)
> {
> - return bs->front_pad + sizeof(struct bio) +
> - BIO_INLINE_VECS * sizeof(struct bio_vec);
> + return bs->front_pad + sizeof(struct bio) + bs->back_pad;
> }
>
> static struct kmem_cache *bio_find_or_create_slab(struct bio_set *bs)
> @@ -1572,6 +1571,10 @@ int bioset_init(struct bio_set *bs,
> int flags)
> {
> bs->front_pad = front_pad;
> + if (flags & BIOSET_NEED_BVECS)
> + bs->back_pad = BIO_INLINE_VECS * sizeof(struct bio_vec);
> + else
> + bs->back_pad = 0;
>
> spin_lock_init(&bs->rescue_lock);
> bio_list_init(&bs->rescue_list);
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 1edda614f7ce..f606eb1e556f 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -703,6 +703,7 @@ struct bio_set {
> mempool_t bvec_integrity_pool;
> #endif
>
> + unsigned int back_pad;
> /*
> * Deadlock avoidance for stacking block drivers: see comments in
> * bio_alloc_bioset() for details
>

--
Pavel Begunkov