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Re: [Qemu-devel] [PATCH 2/2] qcow2: mark image as corrupt if failing dur
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] qcow2: mark image as corrupt if failing during create |
Date: |
Tue, 19 Feb 2019 10:11:58 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 |
On 2/19/19 6:50 AM, Daniel P. Berrangé wrote:
> During creation we write a minimal qcow2 header and then update it with
> extra features. If the updating fails for some reason we might still be
> left with a valid qcow2 image that will be mistakenly used for I/O. We
> cannot delete the image, since we don't know if we created the
> underlying storage or not. Thus we mark the header as corrupt to
> prevents its later usage.
Should we unconditionally mark the image as corrupt at the time we write
the minimal qcow2 header, and then update the image to non-corrupt on
the final update?
>
> Signed-off-by: Daniel P. Berrangé <address@hidden>
> ---
> block/qcow2.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/block/qcow2.c b/block/qcow2.c
> index ecc577175f..338513e652 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -3104,6 +3104,9 @@ qcow2_co_create(BlockdevCreateOptions *create_options,
> Error **errp)
>
> ret = 0;
> out:
> + if (ret < 0) {
> + qcow2_mark_corrupt(blk_bs(blk));
> + }
If ret < 0 because of an EIO error, this may also fail to write the
change to the header. Hence my question as to whether this is too late.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org