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Re: [PATCH for-5.0] vpc: Don't round up already aligned BAT sizes
From: |
Max Reitz |
Subject: |
Re: [PATCH for-5.0] vpc: Don't round up already aligned BAT sizes |
Date: |
Fri, 3 Apr 2020 10:55:13 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 |
On 02.04.20 11:36, Kevin Wolf wrote:
> As reported on Launchpad, Azure apparently doesn't accept images for
> upload that are not both aligned to 1 MB blocks and have a BAT size that
> matches the image size exactly.
>
> As far as I can tell, there is no real reason why we create a BAT that
> is one entry longer than necessary for aligned image sizes, so change
> that.
>
> (Even though the condition is only mentioned as "should" in the spec and
> previous products accepted larger BATs - but we'll try to maintain
> compatibility with as many of Microsoft's ever-changing interpretations
> of the VHD spec as possible.)
So as far as I can tell we still don’t ensure that the image is aligned
to 1 MB blocks?
Well, as long as it’s at least possible for the user to create valid
images, that’s better.
> Fixes: https://bugs.launchpad.net/bugs/1870098
> Reported-by: Tobias Witek
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
> block/vpc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/block/vpc.c b/block/vpc.c
> index 6df75e22dc..d8141b52da 100644
> --- a/block/vpc.c
> +++ b/block/vpc.c
> @@ -835,7 +835,7 @@ static int create_dynamic_disk(BlockBackend *blk, uint8_t
> *buf,
>
> /* Write the footer (twice: at the beginning and at the end) */
> block_size = 0x200000;
> - num_bat_entries = (total_sectors + block_size / 512) / (block_size /
> 512);
> + num_bat_entries = DIV_ROUND_UP(total_sectors, block_size / 512);
And the old code just looks like a wrong DIV_ROUND_UP() attempt. So:
Reviewed-by: Max Reitz <address@hidden>
>
> ret = blk_pwrite(blk, offset, buf, HEADER_SIZE, 0);
> if (ret < 0) {
>
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