On Mon, Aug 16 2010 at 12:52pm -0400, Tejun Heo <tj@xxxxxxxxxx> wrote: > From: Tejun Heo <tj@xxxxxxxxxx> > > This patch converts dm to support REQ_FLUSH/FUA instead of now > deprecated REQ_HARDBARRIER. What tree does this patch apply to? I know it doesn't apply to v2.6.36-rc1, e.g.: http://git.kernel.org/linus/708e929513502fb0 > For bio-based dm, ... > * -EOPNOTSUPP retry logic dropped. That logic wasn't just about retries (at least not in the latest kernel). With commit 708e929513502fb0 the -EOPNOTSUPP checking also serves to optimize the barrier+discard case (when discards aren't supported). > For request-based dm, > > * Nothing much changes. It just needs to handle FLUSH requests as > before. It would be beneficial to advertise FUA capability so that > it can propagate FUA flags down to member request_queues instead of > sequencing it as WRITE + FLUSH at the top queue. Can you expand on that TODO a bit? What is the mechanism to propagate FUA down to a DM device's members? I'm only aware of propagating member devices' features up to the top-level DM device's request-queue (not the opposite). Are you saying that establishing the FUA capability on the top-level DM device's request_queue is sufficient? If so then why not make the change? > Lightly tested linear, stripe, raid1, snap and crypt targets. Please > proceed with caution as I'm not familiar with the code base. This is concerning... if we're to offer more comprehensive review I think we need more detail on what guided your changes rather than details of what the resulting changes are. Mike -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
