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Date: Sun, 16 Aug 2009 17:48:42 +0100
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] [PATCH] qcow2: Metadata preallocation
Message-ID: <20090816164841.GA27122@shareable.org>
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To: Filip Navara <filip.navara@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org

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?

-- Jamie