On Fri, Mar 17, 2017 at 10:15 AM, Paolo Bonzini <pbonz...@redhat.com> wrote: > > > On 17/03/2017 18:11, Paolo Bonzini wrote: >> >> >> On 17/03/2017 17:55, Ed Swierk wrote: >>> I'm running into the same problem taking an external snapshot with a >>> virtio-blk drive with iothread, so it's not specific to virtio-scsi. >>> Run a Linux guest on qemu master >>> >>> qemu-system-x86_64 -nographic -enable-kvm -monitor >>> telnet:0.0.0.0:1234,server,nowait -m 1024 -object >>> iothread,id=iothread1 -drive file=/x/drive.qcow2,if=none,id=drive0 >>> -device virtio-blk-pci,iothread=iothread1,drive=drive0 >>> >>> Then in the monitor >>> >>> snapshot_blkdev drive0 /x/snap1.qcow2 >>> >>> qemu bombs with >>> >>> qemu-system-x86_64: /x/qemu/include/block/aio.h:457: >>> aio_enable_external: Assertion `ctx->external_disable_cnt > 0' failed. >>> >>> whereas without the iothread the assertion failure does not occur. >> >> Please try this patch: > > Hmm, no. I'll post the full fix on top of John Snow's patches.
OK. Incidentally, testing with virtio-blk I bisected the assertion failure to b2c2832c6140cfe3ddc0de2d77eeb0b77dea8fd3 ("block: Add Error parameter to bdrv_append()"). --Ed