Re: [Ocfs2-devel] [RFC PATCH 02/34] block: introduce and use bio_new

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

FYI your email is completely unreadable to those not using html.
I can't tell what you wrote and what Damien wrote.

On Thu, Jan 28, 2021 at 08:33:10AM +0000, Chaitanya Kulkarni wrote:
> On 1/27/21 11:21 PM, Damien Le Moal wrote:
> 
> On 2021/01/28 16:12, Chaitanya Kulkarni wrote:
> 
> 
> Introduce bio_new() helper and use it in blk-lib.c to allocate and
> initialize various non-optional or semi-optional members of the bio
> along with bio allocation done with bio_alloc(). Here we also calmp the
> max_bvecs for bio with BIO_MAX_PAGES before we pass to bio_alloc().
> 
> Signed-off-by: Chaitanya Kulkarni 
> <chaitanya.kulkarni@xxxxxxx><mailto:chaitanya.kulkarni@xxxxxxx>
> ---
>  block/blk-lib.c     |  6 +-----
>  include/linux/bio.h | 25 +++++++++++++++++++++++++
>  2 files changed, 26 insertions(+), 5 deletions(-)
> 
> diff --git a/block/blk-lib.c b/block/blk-lib.c
> index fb486a0bdb58..ec29415f00dd 100644
> --- a/block/blk-lib.c
> +++ b/block/blk-lib.c
> @@ -14,17 +14,13 @@ struct bio *blk_next_bio(struct bio *bio, struct 
> block_device *bdev,
>                         sector_t sect, unsigned op, unsigned opf,
>                         unsigned int nr_pages, gfp_t gfp)
>  {
> -       struct bio *new = bio_alloc(gfp, nr_pages);
> +       struct bio *new = bio_new(bdev, sect, op, opf, gfp, nr_pages);
> 
>         if (bio) {
>                 bio_chain(bio, new);
>                 submit_bio(bio);
>         }
> 
> -       new->bi_iter.bi_sector = sect;
> -       bio_set_dev(new, bdev);
> -       bio_set_op_attrs(new, op, opf);
> -
>         return new;
>  }
> 
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index c74857cf1252..2a09ba100546 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -826,5 +826,30 @@ static inline void bio_set_polled(struct bio *bio, 
> struct kiocb *kiocb)
>         if (!is_sync_kiocb(kiocb))
>                 bio->bi_opf |= REQ_NOWAIT;
>  }
> +/**
> + * bio_new -   allcate and initialize new bio
> + * @bdev:      blockdev to issue discard for
> + * @sector:    start sector
> + * @op:                REQ_OP_XXX from enum req_opf
> + * @op_flags:  REQ_XXX from enum req_flag_bits
> + * @max_bvecs: maximum bvec to be allocated for this bio
> + * @gfp_mask:  memory allocation flags (for bio_alloc)
> + *
> + * Description:
> + *    Allocates, initializes common members, and returns a new bio.
> + */
> +static inline struct bio *bio_new(struct block_device *bdev, sector_t sector,
> +                                 unsigned int op, unsigned int op_flags,
> +                                 unsigned int max_bvecs, gfp_t gfp_mask)
> +{
> +       unsigned nr_bvec = clamp_t(unsigned int, max_bvecs, 0, BIO_MAX_PAGES);
> +       struct bio *bio = bio_alloc(gfp_mask, nr_bvec);
> 
> 
> I think that depending on the gfp_mask passed, bio can be NULL. So this should
> be checked.
> 
> 
> true, I'll add that check.
> 
> 
> 
> 
> +
> +       bio_set_dev(bio, bdev);
> +       bio->bi_iter.bi_sector = sector;
> +       bio_set_op_attrs(bio, op, op_flags);
> 
> 
> This function is obsolete. Open code this.
> 
> 
> true, will do.
> 
> 
> 
> 
> +
> +       return bio;
> +}
> 
>  #endif /* __LINUX_BIO_H */
> 
> 
> 
> Thanks for the comments Damien.

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