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

From: Vitaly Kuznetsov
Date: Wed Sep 23 2015 - 07:33:08 EST


Christoph Hellwig <hch@xxxxxxxxxxxxx> 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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