On 11/14/2016 03:50 AM, Kevin Wolf wrote: > 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?
Patch was posted here: https://lists.gnu.org/archive/html/qemu-devel/2016-11/msg01603.html -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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