As already mentioned in my email to the fuse developer mailing list, we have also tried to create direct i/o traffic on the affected mount directly but were not able to reproduce the issue. The problem only ever occurs once Qemu starts to run stuff on top of the FUSE mount. Other reports of this issue (identical or similar) have mentioned Qemu or VMware-based emulation as well.
As already mentioned in my email to the fuse developer mailing list, we have also tried to create direct i/o traffic on the affected mount directly but were not able to reproduce the issue. The problem only ever occurs once Qemu starts to run stuff on top of the FUSE mount. Other reports of this issue (identical or similar) have mentioned Qemu or VMware-based emulation as well.