Re: [Qemu-devel] qcow1 compression

[Kevin Wolf]

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