From: Jeff Moyer <jmoyer@redhat.com>
Subject: Re: [RFC PATCH 0/7] dax, ext4: Synchronous page faults
Date: Thu, 27 Jul 2017 10:09:07 -0400
Message-ID: <x49zibq3rb0.fsf@segfault.boston.devel.redhat.com>
References: <20170727131245.28279-1-jack@suse.cz>
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Cc: <linux-fsdevel@vger.kernel.org>,
        Christoph Hellwig <hch@infradead.org>,
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        linux-xfs@vger.kernel.org, Andy Lutomirski <luto@kernel.org>,
        linux-ext4@vger.kernel.org
To: Jan Kara <jack@suse.cz>
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In-Reply-To: <20170727131245.28279-1-jack@suse.cz> (Jan Kara's message of
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Jan Kara <jack@suse.cz> writes:

Hi, Jan,

Thanks for looking into this!

> There are couple of open questions with this implementation:
>
> 1) Is it worth the hassle?
> 2) Is S_SYNC good flag to use or should we use a new inode flag?
> 3) VM_FAULT_RO and especially passing of resulting 'pfn' from
>    dax_iomap_fault() through filesystem fault handler to dax_pfn_mkwrite() in
>    vmf->orig_pte is a bit of a hack. So far I'm not sure how to refactor
>    things to make this cleaner.

4) How does an application discover that it is safe to flush from
   userspace?

-Jeff