Re: [Qemu-devel] [PATCH] qemu-io: add flag to mark files growable

[Christoph Hellwig <hch@lst.de>]

On Mon, Jul 06, 2009 at 12:40:06PM +0200, Kevin Wolf wrote:
> Ok, you are right. raw was the only exception because it could be used
> as a protocol even though it didn't have a protocol name.
> 
> Looks fine to me then if you enforce the limitation instead of only
> printing an error message and opening the image anyway. Not printing the
> error and opening the image would be fine either. I just don't like
> error messages without errors.

Well, the primary use of qemu-iotests is to try out the I/O patterns,
and the -g option is to check out we do the correct thing for growable
files, so I'd really prefer it to fail if we're not allow to actually
make it growable.

Now one think I could do is to just add a growable flag to the
BlockDriver to make it explicit.  Currently only raw files (in the posix
and win32 flavours) would set it.  That would also fix the bug what we
currenly allow to grow host devices even if we can't.