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From: Jeff Moyer <jmoyer@redhat.com>
To: Dave Chinner <david@fromorbit.com>
Cc: linux-nvdimm@ml01.01.org, "J. Bruce Fields" <bfields@fieldses.org>,
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        Jan Kara <jack@suse.com>, linux-fsdevel@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <matthew.r.wilcox@intel.com>
Subject: Re: [RFC 00/11] DAX fsynx/msync support
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X-PCLoadLetter: What the f**k does that mean?
Date: Wed, 04 Nov 2015 13:34:58 -0500
In-Reply-To: <x49twp4p11j.fsf@segfault.boston.devel.redhat.com> (Jeff Moyer's
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Jeff Moyer <jmoyer@redhat.com> writes:

>> Hence once the filesystem has waited on the REQ_WRITE|REQ_FLUSH IO
>> to complete, we know that all the earlier REQ_WRITE IOs are on
>> stable storage, too. Hence there's no need for the elevator to drain
>> the queue to guarantee completion ordering - the dispatch ordering
>> and flush/fua write semantics guarantee that when the flush/fua
>> completes, all the IOs dispatch prior to that flush/fua write are
>> also on stable storage...
>
> Des xfs rely on this model for correctness?  If so, I'd say we've got a
> problem.

Dave?