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Re: [Qemu-devel] [PATCH v6 2/2] qemu-img: Document --force-share / -U
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH v6 2/2] qemu-img: Document --force-share / -U |
Date: |
Tue, 30 Jan 2018 08:23:50 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 01/30/2018 12:34 AM, Fam Zheng wrote:
> Signed-off-by: Fam Zheng <address@hidden>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> qemu-img.texi | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/qemu-img.texi b/qemu-img.texi
> index 60a0e080c6..ec7e2f5d1e 100644
> --- a/qemu-img.texi
> +++ b/qemu-img.texi
> @@ -86,6 +86,13 @@ exclusive with the @var{-O} parameters. It is currently
> required to also use
> the @var{-n} parameter to skip image creation. This restriction may be
> relaxed
> in a future release.
>
> address@hidden --force-share (-U)
> +If specified, @code{qemu-img} will open the image in shared mode, allowing
> +concurrent writers. For example, this can be used to get the image
> information
Actually, we only permit one writer at a time. Would it be better to
say "allowing a concurrent writer"?
> +(with 'info' subcommand) when the image is used by a running guest. Note
> that
> +this could produce inconsistent results because of concurrent metadata
> changes,
> +etc. This option is only allowed when opening images in read-only mode.
After all, we are stating that this process (which must be read-only,
because we can't have two writers at once) is permitting some other
process to be the concurrent writer (but not multiple processes to be
concurrent writers)
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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