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Date:   Wed, 1 Jun 2022 00:11:40 -0700
From:   Eric Biggers <ebiggers@kernel.org>
To:     Keith Busch <kbusch@fb.com>
Cc:     linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
        linux-nvme@lists.infradead.org, axboe@kernel.dk,
        Kernel Team <Kernel-team@fb.com>, hch@lst.de,
        bvanassche@acm.org, damien.lemoal@opensource.wdc.com,
        pankydev8@gmail.com, Keith Busch <kbusch@kernel.org>
Subject: Re: [PATCHv5 00/11] direct-io dma alignment
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References: <20220531191137.2291467-1-kbusch@fb.com>
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On Tue, May 31, 2022 at 12:11:26PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> The most significant change from v4 is the alignment is now checked
> prior to building the bio. This gets the expected EINVAL error for
> misaligned userspace iovecs in all cases now (Eric Biggers).
> 
> I've removed the legacy fs change, so only iomap filesystems get to use
> this alignement capability (Christoph Hellwig).
> 
> The block fops check for alignment returns a bool now (Damien).
> 
> Adjusted some comments, docs, and other minor style issues.
> 
> Reviews added for unchanged or trivially changed patches, removed
> reviews for ones that changed more significantly.
> 
> As before, I tested using 'fio' with forced misaligned user buffers on
> raw block, xfs, and ext4 (example raw block profile below).
> 

I still don't think you've taken care of all the assumptions that bv_len is a
multiple of logical block size, or at least SECTOR_SIZE.  Try this:

	git grep -E 'bv_len (>>|/)'

Also:

	git grep '<.*bv_len;'

Also take a look at bio_for_each_segment(), specifically how iter->bi_sector is
updated.

- Eric