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From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: <lsf-pc@lists.linux-foundation.org>
Cc: <linux-fsdevel@vger.kernel.org>, <linux-nvdimm@lists.01.org>
Subject: [LSF/MM TOPIC] Standardizing semantics around the per-file DAX flag
Date: Wed, 13 Feb 2019 11:40:39 -0500	[thread overview]
Message-ID: <20190213164039.GA16285@mit.edu> (raw)

There's been a long-term disagreement about how the per-file DAX flag
should work.

       * Should it exist at all?
       * What happens when the DAX flag is cleared?
           * Should it be not allowed and return an error?
	       (Or maybe only if the file is otherwise opened anywhere in the system?)
	   * Should it only takes effect when the file system is unmounted,
	     or when the inode drops out of the inode cache?
	* Should we remove the flag entirely and make it be something the
	  system automagically infers?

I had hoped consensus would be achieved before the ext4 per-file DAX
flag lands, but it hasn't for a *long* time.  Technically the DAX flag
is "experimental", which technically means it could be removed ---
although I suspect at this point, it would break some userspace, so
our options about how to adjust the semantics of the flag are probably
constrained.

						- Ted

             reply	other threads:[~2019-02-13 16:40 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-13 16:40 Theodore Y. Ts'o [this message]
2019-02-19 12:35 ` [LSF/MM TOPIC] Standardizing semantics around the per-file DAX flag Jan Kara

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