* [Qemu-devel] qcow1 compression
@ 2009-01-07 17:24 Ulrich Hecht
2009-01-07 17:56 ` Kevin Wolf
0 siblings, 1 reply; 3+ messages in thread
From: Ulrich Hecht @ 2009-01-07 17:24 UTC (permalink / raw)
To: qemu-devel
Hi!
I have received a bug report from one of our users about compression in
qcow(1). He converted disk images to qcow with compression, and the
resulting images did not work. I looked into block-qcow.c and found
several huge and, as it seems, long-standing bugs. For instance,
QCOW_OFLAG_COMPRESSED is never set anywhere, causing compressed data to
be returned verbatim on reading.
I'd like to get people's opinion on whether there is any point in fixing
this stuff, considering that there is qcow2, and that it never worked to
begin with. Perhaps a patch removing it would make more sense...
CU
Uli
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] qcow1 compression
2009-01-07 17:24 [Qemu-devel] qcow1 compression Ulrich Hecht
@ 2009-01-07 17:56 ` Kevin Wolf
2009-01-08 12:15 ` Ulrich Hecht
0 siblings, 1 reply; 3+ messages in thread
From: Kevin Wolf @ 2009-01-07 17:56 UTC (permalink / raw)
To: qemu-devel
Ulrich Hecht schrieb:
> I have received a bug report from one of our users about compression in
> qcow(1). He converted disk images to qcow with compression, and the
> resulting images did not work. I looked into block-qcow.c and found
> several huge and, as it seems, long-standing bugs. For instance,
> QCOW_OFLAG_COMPRESSED is never set anywhere, causing compressed data to
> be returned verbatim on reading.
>
> I'd like to get people's opinion on whether there is any point in fixing
> this stuff, considering that there is qcow2, and that it never worked to
> begin with. Perhaps a patch removing it would make more sense...
It definitely worked at some point and a quick look seems to show that
the last patch to block-qcow.c (Rev 4673) breaks it. Despite the commit
comment, the code wasn't all that dead: allocate == 2 is different from
allocate == 1.
Reverting that patch should be enough (and possibly adding a comment so
that it won't be broken again in future).
Kevin
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] qcow1 compression
2009-01-07 17:56 ` Kevin Wolf
@ 2009-01-08 12:15 ` Ulrich Hecht
0 siblings, 0 replies; 3+ messages in thread
From: Ulrich Hecht @ 2009-01-08 12:15 UTC (permalink / raw)
To: qemu-devel
On Wednesday 07 January 2009, Kevin Wolf wrote:
> Reverting that patch should be enough (and possibly adding a comment
> so that it won't be broken again in future).
Yes, that worked for me.
CU
Uli
--
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
^ permalink raw reply [flat|nested] 3+ messages in thread
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2009-01-07 17:24 [Qemu-devel] qcow1 compression Ulrich Hecht
2009-01-07 17:56 ` Kevin Wolf
2009-01-08 12:15 ` Ulrich Hecht
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