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Re: [Qemu-devel] [PATCH] qcow2: Metadata preallocation
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH] qcow2: Metadata preallocation |
Date: |
Mon, 17 Aug 2009 09:16:09 +0200 |
User-agent: |
Thunderbird 2.0.0.21 (X11/20090320) |
Jamie Lokier schrieb:
> Filip Navara wrote:
>> FILE_ATTRIBUTE_SPARSE_FILE? You can't actually set it when
>> opening/creating the file, a separate call to
>> DeviceIoControl/FSCTL_SET_SPARSE is needed.
>
> I see that you increase the file size by writing zeros to the end.
>
> Can't you use the Windows equivalent of unix ftruncate() to extend the
> file instead, after FSCTL_SET_SPARSE?
There actually exists a bdrv_truncate(). I wasn't aware of that. If you
prefer, I can resend the patch with bdrv_truncate instead of a zero write.
Kevin