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Re: [Qemu-devel] [PATCH] block/mirror: limit qiov to IOV_MAX elements
From: |
Jeff Cody |
Subject: |
Re: [Qemu-devel] [PATCH] block/mirror: limit qiov to IOV_MAX elements |
Date: |
Thu, 6 Aug 2015 04:50:17 -0400 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Jul 01, 2015 at 03:45:50PM +0100, Stefan Hajnoczi wrote:
> If mirror has more free buffers than IOV_MAX, preadv(2)/pwritev(2)
> EINVAL failures may be encountered.
>
> It is possible to trigger this by setting granularity to a low value
> like 8192.
>
> This patch stops appending chunks once IOV_MAX is reached.
>
> The spurious EINVAL failure can be reproduced with a qcow2 image file
> and the following QMP invocation:
>
> qmp.command('drive-mirror', device='virtio0', target='/tmp/r7.s1',
> granularity=8192, sync='full', mode='absolute-paths',
> format='raw')
>
> While the guest is running dd if=/dev/zero of=/var/tmp/foo oflag=direct
> bs=4k.
>
Thanks,
Applied to my 'block-next' branch:
https://github.com/codyprime/qemu-kvm-jtc/tree/block-next
-Jeff
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