Am 24.10.2016 um 22:32 hat Eric Blake geschrieben: > On 10/21/2016 08:14 AM, Ed Swierk wrote: > > On Thu, Oct 20, 2016 at 6:38 PM, Eric Blake <ebl...@redhat.com> wrote: > >> On 10/20/2016 07:24 PM, Ed Swierk wrote: > >>> Changing max_transfer in the normal write case to > >>> MIN_NON_ZERO(alignment, MAX_WRITE_ZEROES_BOUNCE_BUFFER) appears to fix > >>> the problem, but I don't pretend to understand all the subtleties > >>> here. > >> > >> That actually sounds like the right fix. But since the bug was probably > >> caused by my code, I'll formalize it into a patch and see if I can > >> modify the testsuite to give it coverage. > > > > If alignment > MAX_WRITE_ZEROES_BOUNCE_BUFFER (however unlikely) we > > have the same problem, so maybe this would be better? > > Our qcow2 support is currently limited to a maximum of 2M clusters; > while MAX_WRITE_ZEROES_BOUNCE_BUFFER is 32k * 512, or 16M. The > maximum-size bounce buffer should not be the problem here; but for some > reason, it looks like alignment is larger than max_transfer which should > not normally be possible. I'm still playing with what should be the > right patch, but hope to have something posted soon.
Are you still playing with it? Kevin
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