From: Waiman Long <waiman.long@hpe.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Theodore Ts'o <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
<linux-ext4@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>
Subject: Re: [RFC PATCH] ext4: Don't release mutex for DAX write
Date: Tue, 3 May 2016 11:58:46 -0400 [thread overview]
Message-ID: <5728CAB6.4050101@hpe.com> (raw)
In-Reply-To: <20160503084343.GA31363@infradead.org>
On 05/03/2016 04:43 AM, Christoph Hellwig wrote:
> As explained in another thread I really think we need to get DAX
> to stop pretending to be direct I/O, which should also take care
> of the locking. The same issue also exists for ext2 and XFS so it
> needs to be solved at a higher level.
I think the DAX code was in the DIO path because it didn't want to use
buffer cache at all. Taking DAX out from DIO will mean having a third
mode of doing I/O which is similar to DIO in certain ways, but not
exactly the same. There will be a certain amount of code duplication in
this case. Do we really want to do that?
As for the locking problem, xfs doesn't seem to have issue as it uses a
rwsem in the xfs inode for synchronization. I haven't looked into the
ext2 code to see if there is any issue there.
Cheers,
Longman
prev parent reply other threads:[~2016-05-03 15:59 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-02 19:58 [RFC PATCH] ext4: Don't release mutex for DAX write Waiman Long
2016-05-03 8:43 ` Christoph Hellwig
2016-05-03 15:58 ` Waiman Long [this message]
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