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[Qemu-devel] Re: [PATCH] block: Enable fall-back to read-only for backin
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] Re: [PATCH] block: Enable fall-back to read-only for backing file |
Date: |
Mon, 01 Feb 2010 09:46:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.5) Gecko/20091209 Fedora/3.0-4.fc12 Thunderbird/3.0 |
Am 31.01.2010 17:49, schrieb Naphtali Sprei:
> There's a problem when trying to use an image file based on a read-only image
> file.
> Before this patch, qemu fails to open the base image and stop.
> With this patch, qemu tries to open the backing file with same permissions as
> the "top" file,
> but if it fails, qemu tries to open it with read-only permissions. If
> succeeded it goes on.
>
> This fall-back works both for an image file based on a read-only file
> and also for a read-only file opened with the snapshot attribute/mode (where
> the real file is the backing file
> for the snapshot file).
>
> Is it better to always open the backing file with read-only mode ? this will
> be more consistent/predictable ?
I would love to open them read-only unconditionally, but we can't. It
would break the commit monitor command. I think the read-only fallback
is appropriate for backing files.
Kevin
- [Qemu-devel] Re: [PATCH] block: Enable fall-back to read-only for backing file,
Kevin Wolf <=