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Re: [Qemu-devel] [PATCH v4 1/4] block/vhdx.c: Don't blindly update the h
From: |
Max Reitz |
Subject: |
Re: [Qemu-devel] [PATCH v4 1/4] block/vhdx.c: Don't blindly update the header |
Date: |
Tue, 14 Nov 2017 16:17:32 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 |
On 2017-11-07 14:10, Jeff Cody wrote:
> The VHDX specification requires that before user data modification of
> the vhdx image, the VHDX header file and data GUIDs need to be updated.
> In vhdx_open(), if the image is set to RDWR, we go ahead and update the
> header.
>
> However, just because the image is set to RDWR does not mean we can go
> ahead and write at this point - specifically, if the QEMU run state is
> INMIGRATE, the underlying file BS may be set to inactive via the BDS
> open flag of BDRV_O_INACTIVE. Attempting to write under this condition
> will cause an assert in bdrv_co_pwritev().
>
> We can alternatively latch the first time the image is written. And lo
> and behold, we do just that, via vhdx_user_visible_write() in
> vhdx_co_writev(). This means the call to vhdx_update_headers() in
> vhdx_open() is likely just vestigial, and can be removed.
>
> Reported-by: Alexey Kardashevskiy <address@hidden>
> Tested-by: Alexey Kardashevskiy <address@hidden>
> Signed-off-by: Jeff Cody <address@hidden>
> ---
> block/vhdx.c | 7 -------
> 1 file changed, 7 deletions(-)
>
> diff --git a/block/vhdx.c b/block/vhdx.c
> index 7ae4589..9956933 100644
> --- a/block/vhdx.c
> +++ b/block/vhdx.c
> @@ -1008,13 +1008,6 @@ static int vhdx_open(BlockDriverState *bs, QDict
> *options, int flags,
> goto fail;
> }
>
> - if (flags & BDRV_O_RDWR) {
> - ret = vhdx_update_headers(bs, s, false, NULL);
And this doesn't even update the data GUID...
Max
> - if (ret < 0) {
> - goto fail;
> - }
> - }
> -
> /* TODO: differencing files */
>
> return 0;
>
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- [Qemu-devel] [PATCH v4 0/4] Don't write headers if BDS is INACTIVE, Jeff Cody, 2017/11/07
- [Qemu-devel] [PATCH v4 1/4] block/vhdx.c: Don't blindly update the header, Jeff Cody, 2017/11/07
- Re: [Qemu-devel] [PATCH v4 1/4] block/vhdx.c: Don't blindly update the header,
Max Reitz <=
- [Qemu-devel] [PATCH v4 3/4] block/parallels: add migration blocker, Jeff Cody, 2017/11/07
- [Qemu-devel] [PATCH v4 2/4] block/parallels: Do not update header or truncate image when INMIGRATE, Jeff Cody, 2017/11/07
- [Qemu-devel] [PATCH v4 4/4] qemu-iotests: update unsupported image formats in 194, Jeff Cody, 2017/11/07
- Re: [Qemu-devel] [Qemu-block] [PATCH v4 0/4] Don't write headers if BDS is INACTIVE, Stefan Hajnoczi, 2017/11/09
- Re: [Qemu-devel] [PATCH v4 0/4] Don't write headers if BDS is INACTIVE, Denis V. Lunev, 2017/11/09
- Re: [Qemu-devel] [PATCH v4 0/4] Don't write headers if BDS is INACTIVE, Max Reitz, 2017/11/14