Re: [PATCH V3] bio: modify __bio_add_page() to accept pages that don't start a new segment

From: Maurizio Lombardi
Date: Tue May 27 2014 - 10:27:59 EST


On Tue, May 27, 2014 at 10:04:58PM +0800, Ming Lei wrote:
>
> Looks your approach is simpler.
>
> But looks there is one problem if I understand correctly:
> __blk_recalc_rq_segments() may not cover the last vector
> because bio->bi_iter.bi_size isn't updated until the end of
> __bio_add_page().
>
> But it shouldn't have been related with current virtio-blk problem.
>

This is a valid point, bi_iter.bi_size influences the behaviour of
blk_recount_segments(). Maybe Jens can confirm your observation.

Anyway it doesn't explain the reason behind the regression
introduced by commit 3979ef4dcf

Maurizio Lombardi
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