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Date:   Thu, 19 May 2022 11:43:09 -0600
From:   Keith Busch <kbusch@kernel.org>
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Keith Busch <kbusch@fb.com>, linux-fsdevel@vger.kernel.org,
        linux-block@vger.kernel.org, axboe@kernel.dk,
        Kernel Team <Kernel-team@fb.com>, hch@lst.de,
        bvanassche@acm.org, damien.lemoal@opensource.wdc.com
Subject: Re: [PATCHv2 3/3] block: relax direct io memory alignment
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On Thu, May 19, 2022 at 10:27:04AM -0700, Eric Biggers wrote:
> On Thu, May 19, 2022 at 11:01:05AM -0600, Keith Busch wrote:
> > On Wed, May 18, 2022 at 10:56:04PM -0600, Keith Busch wrote:
> > > On Wed, May 18, 2022 at 08:27:31PM -0700, Eric Biggers wrote:
> > > > Note, there's also lots of code that assumes that bio_vec::bv_len is a multiple
> > > > of 512.  
> > > 
> > > Could you point me to some examples?
> > 
> > Just to answer my own question, blk-crypto and blk-merge appear to have these
> > 512 byte bv_len assumptions.
> 
> blk_bio_segment_split() and bio_advance_iter() are two more examples.

I agree about blk_bio_segment_split(), but bio_advance_iter() looks fine. That
just assumes the entire length is a multiple of 512, not any particular bvec.

Anyway, I accept your point that some existing code has this assumption, and
will address these before the next revision.