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Re: [PATCH] block: fix bio splitting on max sectors

From Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups linux.kernel
Subject Re: [PATCH] block: fix bio splitting on max sectors
Date 2016-01-22 19:50 +0100
Message-ID <qTOWt-7Yf-9@gated-at.bofh.it> (permalink)
References <qTOMN-7Ux-1@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Fri, Jan 22, 2016 at 10:29 AM, Ming Lei <tom.leiming@gmail.com> wrote:
>
> This patch fixes the issue by making the max io size aligned
> to logical block size.

Looks better, thanks.

I'd suggest also moving the "max_sectors" variable into the
bio_for_each_segment() loop too just to keep variables with minimal
scope, but at least this is fairly legible.

Also:

> +static inline unsigned get_max_io_size(struct request_queue *q,
> +                                      struct bio *bio)
> +{
> +       unsigned sectors = blk_max_size_offset(q, bio->bi_iter.bi_sector);
> +       unsigned mask = ~(queue_logical_block_size(q) - 1);
> +
> +       /* aligned to logical block size */
> +       sectors = ((sectors << 9) & mask) >> 9;

this could be written as

        unsigned mask = queue_logical_block_size(q) - 1;

        sectors = sectors & ~(mask >> 9);

avoiding the extra shift. That also avoids the possible overflow that
that extra left-shift introduces. Hmm?

                 Linus

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Thread

[PATCH] block: fix bio splitting on max sectors Ming Lei <tom.leiming@gmail.com> - 2016-01-22 19:40 +0100
  Re: [PATCH] block: fix bio splitting on max sectors Linus Torvalds <torvalds@linux-foundation.org> - 2016-01-22 19:50 +0100
    Re: [PATCH] block: fix bio splitting on max sectors Keith Busch <keith.busch@intel.com> - 2016-01-22 21:20 +0100
      Re: [PATCH] block: fix bio splitting on max sectors Keith Busch <keith.busch@intel.com> - 2016-01-22 21:40 +0100
      Re: [PATCH] block: fix bio splitting on max sectors Linus Torvalds <torvalds@linux-foundation.org> - 2016-01-22 21:40 +0100

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