Re: [Qemu-devel] [PATCHv2 10/11] iscsi: ignore aio_discard if unsupported

[Kevin Wolf]

Am 10.07.2013 um 16:49 hat Peter Lieven geschrieben:
> Am 10.07.2013 16:28, schrieb Kevin Wolf:
> > Am 10.07.2013 um 16:04 hat Peter Lieven geschrieben:
> >> Am 10.07.2013 13:33, schrieb Kevin Wolf:
> >>> Am 27.06.2013 um 15:11 hat Peter Lieven geschrieben:
> >>>> if the target does not support UNMAP or the request
> >>>> is too big silently ignore the discard request.
> >>>>
> >>>> Signed-off-by: Peter Lieven <address@hidden>
> >>> Why not loop for the "too big" case? You can probably use the same logic
> >>> for unmapping the whole device in .bdrv_create and here.
> >> right, but looping in an aio function seemed not so trivial to me.
> >> it seems more and more obvious to me that the best would be to change
> >> all the remaining aio routines to co routines.
> > The pattern for AIO functions is that the real work of submitting
> > requests is done in the AIO callback, and it submits new AIO requests
> > calling back into the same callback as long as acb->remaining_secs > 0
> > (or something like that).
> >
> > You can still see that kind of thing alive in qed_aio_next_io(), (most
> > of?) the rest is converted to coroutines because it makes the code look
> > nicer.
> would you agree if I leave the easy version in just to fix the potential
> problems if iscsi_aio_discard is called with too high nb_sectors or
> on a storage where UNMAP is unsupported.
> 
> I will add a TODO with the comment that the limit of iscsi->max_unmap should
> be replaced by a loop once the routine is replaced by a coroutine?

Meh, another pony I don't get... ;-)

Leaving a TODO comment for now is okay with me.

> >> in this case i could add the too big logic in iscsi_co_discard and simply 
> >> call
> >> it from iscsi_co_write_zeroes.
> > I think that would be the nicest solution.
> I promised to take care of this for 1.7.0 latest.

Okay, thanks.

Kevin