[Qemu-devel] Re: [PATCH] vdi: Fix image opening and creation for odd disk sizes

[Kevin Wolf]

Am 06.05.2010 20:29, schrieb Stefan Weil:
> This patch fixes a regression introduced by commit
> 95a2f9bc588c3f83375d87b0a9394f89a1bcfada.
> 
> The fix is based on a patch from Kevin Wolf. Here his comment:
> 
> "The number of blocks needs to be rounded up to cover all of the virtual hard
> disk. Without this fix, we can't even open our own images if their size is not
> a multiple of the block size."
> 
> While Kevin's patch addressed vdi_create, my modification also fixes
> vdi_open which now accepts any image which is large enough to hold
> the blocks.

Shouldn't it be the other way round? That is, an image which has some
unused blocks at its end makes sense, whereas an image with a virtual
disk size that can't be represented with the number of blocks doesn't?

> I also decided to keep the original code in vdi_create which rounds down.
> Rounding works in both directions, and there are good arguments for both,
> so I just left the original simple code.
> 
> It is very important to use the rounded value for the new disk size, too -
> otherwise VirtualBox cannot open our disk image.

So you're saying that in VDI you can't represent disks with an odd size?
The one thing common across image formats seems to be that they are
broken...

Kevin