From: Christoph Hellwig <hch@infradead.org>
To: Ross Zwisler <ross.zwisler@linux.intel.com>,
Jan Kara <jack@suse.cz>, Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>,
Matthew Wilcox <willy@linux.intel.com>,
Christoph Hellwig <hch@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-nvdimm <linux-nvdimm@ml01.01.org>
Subject: Re: [PATCH 2/2] dax: fix bdev NULL pointer dereferences
Date: Sun, 7 Feb 2016 00:38:14 -0800 [thread overview]
Message-ID: <20160207083814.GA695@infradead.org> (raw)
In-Reply-To: <20160205222500.GA15463@linux.intel.com>
On Fri, Feb 05, 2016 at 03:25:00PM -0700, Ross Zwisler wrote:
> According to the standard specification (e.g., POSIX.1-2001), sync()
> schedules the writes, but may return before the actual writing
> is done. However, since version 1.3.20 Linux does actually wait.
> (This still does not guarantee data integrity: modern disks have large
> caches.)
>
> Based on this I don't believe that it is a requirement that sync and syncfs
> actually flush the data durably to media before they return - they just need
> to make sure it has been sent to the device, which is always true for all
> writes PMEM via DAX, even without any calls to dax_writeback_mapping_range().
For Linux there is a requirement to not return before the data is on disk,
and our users rely on it. The man page is rather confusing, and I'll see
if I can fix it up.
next prev parent reply other threads:[~2016-02-07 8:38 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 19:35 [PATCH 1/2] block: fix pfn_mkwrite() DAX fault handler Ross Zwisler
2016-01-28 19:35 ` Ross Zwisler
2016-01-28 19:35 ` [PATCH 2/2] dax: fix bdev NULL pointer dereferences Ross Zwisler
2016-01-28 19:35 ` Ross Zwisler
2016-01-28 20:21 ` Dan Williams
2016-01-28 20:21 ` Dan Williams
2016-01-28 21:38 ` Christoph Hellwig
2016-01-29 18:28 ` Ross Zwisler
2016-01-29 23:34 ` Ross Zwisler
2016-01-30 0:18 ` Dan Williams
2016-01-31 22:44 ` Dave Chinner
2016-01-30 5:28 ` Matthew Wilcox
2016-01-30 6:01 ` Dan Williams
2016-01-30 7:08 ` Jared Hulbert
2016-01-31 2:32 ` Matthew Wilcox
2016-01-31 6:12 ` Ross Zwisler
2016-01-31 10:55 ` Matthew Wilcox
2016-01-31 16:38 ` Dan Williams
2016-01-31 18:07 ` Matthew Wilcox
2016-01-31 18:18 ` Dan Williams
2016-01-31 18:27 ` Matthew Wilcox
2016-01-31 18:50 ` Dan Williams
2016-01-31 19:51 ` Dan Williams
2016-02-01 13:44 ` Matthew Wilcox
2016-02-01 14:51 ` Jan Kara
2016-02-01 20:49 ` Matthew Wilcox
2016-02-01 21:47 ` Dave Chinner
2016-02-02 6:06 ` Jared Hulbert
2016-02-02 6:46 ` Dan Williams
2016-02-02 8:05 ` Jared Hulbert
2016-02-02 16:51 ` Dan Williams
2016-02-02 21:46 ` Jared Hulbert
2016-02-03 0:34 ` Matthew Wilcox
2016-02-03 1:21 ` Jared Hulbert
2016-02-02 11:17 ` Jan Kara
2016-02-02 16:33 ` Dan Williams
2016-02-02 16:46 ` Jan Kara
2016-02-02 17:10 ` Dan Williams
2016-02-02 17:34 ` Ross Zwisler
2016-02-02 17:46 ` Dan Williams
2016-02-02 17:47 ` Dan Williams
2016-02-02 18:24 ` Ross Zwisler
2016-02-02 18:46 ` Matthew Wilcox
2016-02-02 18:59 ` Dan Williams
2016-02-02 20:14 ` Matthew Wilcox
2016-02-03 11:09 ` Jan Kara
2016-02-03 10:46 ` Jan Kara
2016-02-03 20:13 ` Ross Zwisler
2016-02-04 9:15 ` Jan Kara
2016-02-04 23:38 ` Ross Zwisler
2016-02-06 23:15 ` Dave Chinner
2016-02-07 5:27 ` Ross Zwisler
2016-02-04 19:56 ` Ross Zwisler
2016-02-04 20:29 ` Jan Kara
2016-02-04 22:19 ` Ross Zwisler
2016-02-05 22:25 ` Ross Zwisler
2016-02-06 23:40 ` Dave Chinner
2016-02-07 6:43 ` Ross Zwisler
2016-02-08 13:48 ` Jan Kara
2016-02-07 8:38 ` Christoph Hellwig [this message]
2016-02-08 15:55 ` Ross Zwisler
2016-02-02 18:41 ` Ross Zwisler
2016-02-02 18:53 ` Ross Zwisler
2016-02-02 0:02 ` Ross Zwisler
2016-02-02 7:10 ` Dave Chinner
2016-02-02 10:34 ` Jan Kara
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