On Friday June 1, dgc@xxxxxxx wrote: > On Thu, May 31, 2007 at 02:31:21PM -0400, Phillip Susi wrote: > > David Chinner wrote: > > >That sounds like a good idea - we can leave the existing > > >WRITE_BARRIER behaviour unchanged and introduce a new WRITE_ORDERED > > >behaviour that only guarantees ordering. The filesystem can then > > >choose which to use where appropriate.... > > > > So what if you want a synchronous write, but DON'T care about the order? > > submit_bio(WRITE_SYNC, bio); > > Already there, already used by XFS, JFS and direct I/O. Are you sure? You seem to be saying that WRITE_SYNC causes the write to be safe on media before the request returns. That isn't my understanding. I think (from comments near the definition and a quick grep through the code) that WRITE_SYNC expedites the delivery of the request through the elevator, but doesn't do anything special about getting it onto the media. It essentially say "Submit this request now, don't wait for more request to bundle with it for better bandwidth utilisation" NeilBrown -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
