Il 28/05/2013 11:36, Kevin Wolf ha scritto: > Am 28.05.2013 um 11:24 hat Paolo Bonzini geschrieben: >> Il 28/05/2013 11:18, Kevin Wolf ha scritto: >>>>> The other part why I haven't sent a fix yet is that I don't have a test >>>>> case for it. >>>> >>>> Temporarily add a sleep(31) in qemu_fdatasync()? >>>> >>>> I was lazy in testing with -snapshot to not corrupt my disk image, which >>>> would not trigger the same issue since qcow2-backed AFAIU. >>>> >>>>> I guess I need to extend blkdebug first before this can be >>>>> reliably tested by qtest. >>>> >>>> It can't, since it's not a pure device emulation issue but depends on >>>> the relative timing of filesystem operations and subsequent commands. >>> >>> That's why you need to take influence on the timing. It's no excuse for >>> merging without a test case. If we only ever tested devices that have no >>> relation to the outside world, our testing would be pretty useless and >>> always stay as bad as it is today in many areas. >> >> I don't think the qtest would be timing dependent. The Linux testcase >> is timing dependent, but for the qtest all you need to check is "is BUSY >> set during a flush?". This can be done with blkdebug suspend/resume, >> except that there is no way to call bdrv_debug_resume from QEMU. > > That's exactly what I was talking about, suspending a request is taking > influence on its timing. I'm looking into this right now. (And it's not > just resume, bdrv_debug_suspend can't be called from QEMU either)
It can be called from the rules file though, can't it? > In fact, I'm checking whether we can have a monitor command to issue > qemu-io commands, which will be more generally useful for test cases. We > just need to make obvious that it doesn't become an ABI. Maybe prefix it > with "__org.qemu.debug-" or something like that. Makes sense. I'm not sure why you'd want to read or write from testcases, but bdrv_drain(_all) can also be useful from testcases. Paolo