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Date: Thu, 09 Apr 2009 15:42:22 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] qemu-io: Fix handling of bdrv_is_allocated()
	return value
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To: Christoph Hellwig <hch@lst.de>
Cc: qemu-devel@nongnu.org

Christoph Hellwig schrieb:
> On Thu, Apr 09, 2009 at 03:05:27PM +0200, Kevin Wolf wrote:
>> bdrv_is_allocated() returns a boolean which indicates if the offset is
>> allocated, not 0 on success and everything else is an error.
> 
> Yeah, the handling wa wrong before.  But a return value of 0 and *pnum =
> 0 seems to be a special error-ish value still which we might want to
> handle.

The header comment of bdrv_is_allocated() doesn't specify error 
conditions. ;-)

You seem to be right that there is one place in block.c where *pnum = 0 
is used as something like an error return value. This isn't consistent 
though, qcow and vmdk return non-zero values in *pnum under the same 
conditions.

Maybe another patch to change that and bring the error message back 
again on *pnum == 0?

Kevin