From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH 11/13] dax, iomap: Add support for synchronous faults
Date: Thu, 24 Aug 2017 06:38:09 -0700
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Cc: Christoph Hellwig <hch@infradead.org>,
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        Andy Lutomirski <luto@kernel.org>, linux-ext4@vger.kernel.org,
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        Ross Zwisler <ross.zwisler@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Boaz Harrosh <boazh@netapp.com>
To: Jan Kara <jack@suse.cz>
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On Thu, Aug 24, 2017 at 02:34:51PM +0200, Jan Kara wrote:
> In a subtle but important way ;). The main difference is that if the extent
> has been already allocated by previous write, but the changing transaction
> is not yet committed, we will return IOMAP_F_NEEDDSYNC but not IOMAP_F_NEW.

Ok.  How about a IOMAP_F_DIRTY flag and a better explanation?