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

[Neil Brown <neilb suse de>]

On Tuesday May 29, psusi cfl rr com 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