From: Eric Blake <eblake@redhat.com>
To: Fam Zheng <famz@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
qemu-block@nongnu.org, Max Reitz <mreitz@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 0/2] block: Fix qemu-img creating overlay when guest running
Date: Fri, 15 Dec 2017 13:51:29 -0600 [thread overview]
Message-ID: <cf7ac628-39a5-13bd-e234-f9964ea89f05@redhat.com> (raw)
In-Reply-To: <20171215080446.10671-1-famz@redhat.com>
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On 12/15/2017 02:04 AM, Fam Zheng wrote:
> Shared write lock is not strictly necessary for creating the overlay image, if
> all what we want is to probe the size.
Theoretically, the size could be changing due to a resize operation.
But realistically, even if that happens, we will (hopefully) see either
the old size or the new size atomically (that is, I seriously doubt the
size information is split across multiple sectors of the in-use image to
the point that we could shard the read).
Series:
Reviewed-by: Eric Blake <eblake@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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prev parent reply other threads:[~2017-12-15 19:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-15 8:04 [Qemu-devel] [PATCH 0/2] block: Fix qemu-img creating overlay when guest running Fam Zheng
2017-12-15 8:04 ` [Qemu-devel] [PATCH 1/2] block: Open backing image in force share mode for size probe Fam Zheng
2017-12-22 12:49 ` Kevin Wolf
2017-12-15 8:04 ` [Qemu-devel] [PATCH 2/2] iotests: Test creating overlay when guest running Fam Zheng
2017-12-15 19:49 ` Eric Blake
2017-12-22 12:47 ` Kevin Wolf
2017-12-15 19:51 ` Eric Blake [this message]
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