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Date: Fri, 18 Aug 2017 20:04:20 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 5/6] block: Fix write/resize permissions
 for inactive images
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To: Xie Changlong <xiechanglong.d@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, qemu-block@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Max Reitz <mreitz@redhat.com>, Zhang Hailiang <zhang.zhanghailiang@huawei.com>, Zhang Chen <zhangchen.fnst@cn.fujitsu.com>, Wen Congyang <wencongyang2@huawei.com>, qemu-devel@nongnu.org

On Fri, 08/18 18:06, Xie Changlong wrote:
> The root casue is when we run replication in secondary, vmstate changes to
> RUN_STATE_INMIGRATE, then blockdev_init() sets bdrv_flags |=
> BDRV_O_INACTIVE. So the whole chain become readonly. I've tried on my side,
> but it seems not easy to fix it. I wonder if there is any way to bypass
> this? Any suggestion would be appreciated.

The non-shared storage migration uses "nbd_server_add -w" at destinition side
where BDRV_O_INACTIVE is set for images like your case, the way it handles it is
by calling bdrv_invalidate_cache(). See nbd_export_new().

See also commit 3dff24f2dffc5f3aa46dc014122012848bd7959d.

I'm not sure if this is enough for block replication?

Fam