From: Christoph Hellwig <hch@infradead.org>
To: Waiman Long <waiman.long@hpe.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>,
Andreas Dilger <adilger.kernel@dilger.ca>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Matthew Wilcox <willy@linux.intel.com>,
linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@infradead.org>,
Scott J Norton <scott.norton@hpe.com>,
Douglas Hatch <doug.hatch@hpe.com>,
Toshimitsu Kani <toshi.kani@hpe.com>
Subject: Re: [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM
Date: Sun, 1 May 2016 10:28:54 -0700 [thread overview]
Message-ID: <20160501172854.GA19601@infradead.org> (raw)
In-Reply-To: <57238DFC.6010108@hpe.com>
On Fri, Apr 29, 2016 at 12:38:20PM -0400, Waiman Long wrote:
> From my testing, it looked like that parallel overwrites to the same file in
> an ext4 filesystem on DAX can happen in parallel even if their range
> overlaps. It was mainly because the code will drop the i_mutex before the
> write. That means the overlapped blocks can get garbage. I think this is a
> problem, but I am not expert in the ext4 filesystem to say for sure. I would
> like to know your thought on that.
That's another issue with dax I/O pretending to be direct I/O.. Because
it isn't we'll need to synchronize it like buffered I/O and not like
direct I/O in all file systems.
next prev parent reply other threads:[~2016-05-01 17:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-29 16:27 [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-04-29 16:27 ` [PATCH v5 1/2] dax: Don't touch i_dio_count in dax_do_io() Waiman Long
2016-05-05 14:16 ` Jan Kara
2016-05-05 14:27 ` Christoph Hellwig
2016-05-05 15:48 ` Jan Kara
2016-04-29 16:27 ` [PATCH v5 2/2] ext4: Make cache hits/misses per-cpu counts Waiman Long
2016-05-05 14:03 ` Jan Kara
2016-04-29 16:38 ` [PATCH v5 0/2] ext4: Improve parallel I/O performance on NVDIMM Waiman Long
2016-05-01 17:28 ` Christoph Hellwig [this message]
2016-05-02 17:45 ` Waiman Long
2016-05-05 1:57 ` Dave Chinner
2016-05-05 14:19 ` Christoph Hellwig
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