From: Jan Kara <jack@suse.cz>
Subject: Re: [PATCH 11/13] dax, iomap: Add support for synchronous faults
Date: Thu, 24 Aug 2017 14:34:51 +0200
Message-ID: <20170824123451.GA6187@quack2.suse.cz>
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 <20170817160815.30466-12-jack@suse.cz>
 <20170824122720.GA9961@infradead.org>
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Cc: Jan Kara <jack@suse.cz>, linux-fsdevel@vger.kernel.org,
        linux-nvdimm@lists.01.org, Andy Lutomirski <luto@kernel.org>,
        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
        Ross Zwisler <ross.zwisler@linux.intel.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Boaz Harrosh <boazh@netapp.com>
To: Christoph Hellwig <hch@infradead.org>
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On Thu 24-08-17 05:27:20, Christoph Hellwig wrote:
> Just curious:  how does IOMAP_F_NEEDDSYNC practically differ
> from IOMAP_F_NEW?

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.

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR