On Sat, Jul 07 2001, Andrew Morton wrote:
> Jens Axboe wrote:
> > On Sat, Jul 07 2001, Andrew Morton wrote:
> > > For more sophisticated storage systems such as RAID controllers,
> > > I guess we'd have to propagate a SCSI write barrier command down to
> > > the controller itself. I'm not sure that the Linux request
> > > and SCSI layers are up to doing that. Have you looked into it?
> > I have, I wrote a barrier write patch some time ago. SCSI support is the
> > easy part, having the luxury of just setting a tag option.
> Good. Please keep that patch warm.
I've tried to, and I'll put it in the bio-XX patches soon enough.
> Question is: does IDE need it at all? If we can assume
> that the data is safe once the drive has acked it, then that's
> all a journalling fs cares about, yes?
It would enable safe use of write caching, so yes. For a barrier write,
do a sync flush following a write/write_dma/write_dma_queued command
(yes dma_queued has no ordered/sync option, yay ide).