Re: [libvirt] [PATCH] qemu: Refactor parsing of block device IO tuning parameters.

On Thu, Aug 09, 2012 at 10:48:43 +0100, Daniel P. Berrange wrote: > On Thu, Aug 09, 2012 at 11:39:57AM +0200, Jiri Denemark wrote: > > On Thu, Aug 09, 2012 at 10:48:42 +0200, Peter Krempa wrote: > > > # virsh blkdeviotune asdf hda > > > error: Unable to get block I/O throttle parameters > > > error: internal error block_io_throttle field 'total_bytes_sec' missing in qemu's output > > > > I think the old/new error messages can be included directly in the commit > > message. Anyway, I wonder if we should take this as an opportunity to fix the > > "internal error", however I'm not sure what is the best code to use. It seems > > we use OPERATION_INVALID in such cases, which could be good enough. > > No, OPERATION_INVALID is for scenarios where the API request cannot > be performed because the object is in the wrong state. > > eg when you request to pause a VM that is shutoff. > > > This is a case where the data we receive back from QEMU is incorrect. > I don't think we have a current error code that is suitable for this > kind of scenario, so we ought to invent a new one. > > Some ideas > > MISSING_DATA > DATA_INVALID > UNEXPECTED_DATA > ...insert others... > > my favour is probably DATA_INVALID The data is actually correct, just the fields required for this functionality are missing because QEMU is too old to support them. Perhaps OPERATION_UNSUPPORTED (which doesn't currently exist either) could be the right choice.