linux-kernel - Re: [PATCH v3 00/13] dax: fix dma vs truncate and remove 'page-less' support

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Message-ID: <20171029215233.GF3666@dastard>
Date:   Mon, 30 Oct 2017 08:52:33 +1100
From:   Dave Chinner <david@...morbit.com>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     "mhocko@...e.com" <mhocko@...e.com>, "jack@...e.cz" <jack@...e.cz>,
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Subject: Re: [PATCH v3 00/13] dax: fix dma vs truncate and remove 'page-less'
 support

On Fri, Oct 27, 2017 at 01:42:16PM +0200, Dan Williams wrote:
> [replying from my phone, please forgive formatting]
> 
> On Friday, October 27, 2017, Dave Chinner <david@...morbit.com> wrote:
> 
> 
> > > Here are the two primary patches in
> > > the series, do you think the extent-busy approach would be cleaner?
> >
> > The XFS_DAXDMA....
> >
> > $DEITY that patch is so ugly I can't even bring myself to type it.
> 
> 
> Right, and so is the problem it's trying to solve. So where do you want to
> go from here?
> 
> I could go back to the FL_ALLOCATED approach, but use page idle callbacks
> instead of polling for the lease end notification. Or do we want to try
> busy extents? My concern with busy extents is that it requires more per-fs
> code.

I don't care if it takes more per-fs code to solve the problem -
dumping butt-ugly, nasty locking crap into filesystems that
filesystem developers are completely unable to test is about the
worst possible solution you can come up with.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com