Re: [PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer()

From	Vitaly Kuznetsov <vkuznets@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer()
Date	2015-09-23 13:40 +0200
Message-ID	<qbQz0-2RY-7@gated-at.bofh.it> (permalink)
References	<qbyC5-2cv-15@gated-at.bofh.it> <qbDLs-16C-17@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Christoph Hellwig <hch@infradead.org> writes:

> On Tue, Sep 22, 2015 at 06:27:50PM +0200, Vitaly Kuznetsov wrote:
>> Storvsc driver needs to ensure there are no 'holes' in the presented
>> sg list (all segments in the middle of the list need to be of PAGE_SIZE).
>
> I think it should instead set a virt_boundary.  That's what we added for
> the NVMe driver which has the same requirements, and Sagi recently also
> switched iSER to it after we ensured that flag is handled correctly by
> the SG_IO ioctl.

Wow,

I checked and blk_queue_virt_boundary(sdevice->request_queue, PAGE_SIZE
- 1) seems to be solving the issue completely, no bounce buffer
required. I'll test more and send v2 with removing the rest.

-- 
  Vitaly
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[PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-09-22 18:30 +0200
  Re: [PATCH] storvsc: get rid of homegrown  copy_{to,from}_bounce_buffer() Christoph Hellwig <hch@infradead.org> - 2015-09-23 00:00 +0200
    Re: [PATCH] storvsc: get rid of homegrown copy_{to,from}_bounce_buffer() Vitaly Kuznetsov <vkuznets@redhat.com> - 2015-09-23 13:40 +0200

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