Re: [RFD] BIO_RW_BARRIER - what it means for devices, filesystems,and dm/md.

From: Neil Brown
Date: Wed May 30 2007 - 20:23:35 EST


On Tuesday May 29, psusi@xxxxxxxxxx wrote:
> Neil Brown wrote:
> > md/dm modules could keep count of requests as has been suggested
> > (though that would be a fairly big change for raid0 as it currently
> > doesn't know when a request completes - bi_endio goes directly to the
> > filesystem).
>
> Are you sure? I believe that dm handles bi_endio because it waits for
> all in progress bio to complete before switching tables.

I was taking about md/raid0, not dm-stripe.
md/raid0 (and md/linear) currently never know that a request has
completed.

NeilBrown
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