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From: Dave Chinner <david@fromorbit.com>
To: Jan Kara <jack@suse.cz>
Cc: "Williams, Dan J" <dan.j.williams@intel.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"jmoyer@redhat.com" <jmoyer@redhat.com>,
	"hch@lst.de" <hch@lst.de>, "axboe@fb.com" <axboe@fb.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
	"willy@linux.intel.com" <willy@linux.intel.com>,
	"ross.zwisler@linux.intel.com" <ross.zwisler@linux.intel.com>
Subject: Re: [PATCH 5/5] block: enable dax for raw block devices
Date: Mon, 26 Oct 2015 08:22:47 +1100	[thread overview]
Message-ID: <20151025212247.GI19199@dastard> (raw)
In-Reply-To: <20151022210818.GC8670@quack.suse.cz>

On Thu, Oct 22, 2015 at 11:08:18PM +0200, Jan Kara wrote:
> Ugh2: Now I realized that DAX mmap isn't safe wrt fs freezing even for
> filesystems since there's nothing which writeprotects pages that are
> writeably mapped. In normal path, page writeback does this but that doesn't
> happen for DAX. I remember we once talked about this but it got lost.
> We need something like walk all filesystem inodes during fs freeze and
> writeprotect all pages that are mapped. But that's going to be slow...

fsync() has the same problem - we have no record of the pages that
need to be committed and then write protected when fsync() is called
after write()...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  parent reply	other threads:[~2015-10-25 21:23 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-22  6:41 [PATCH 0/5] block, dax: updates for 4.4 Dan Williams
2015-10-22  6:41 ` [PATCH 1/5] pmem, dax: clean up clear_pmem() Dan Williams
2015-10-22  6:41 ` [PATCH 2/5] dax: increase granularity of dax_clear_blocks() operations Dan Williams
2015-10-22  9:26   ` Jan Kara
2015-10-22  6:41 ` [PATCH 3/5] block, dax: fix lifetime of in-kernel dax mappings with dax_map_atomic() Dan Williams
2015-10-22  6:42 ` [PATCH 4/5] block: introduce file_bd_inode() Dan Williams
2015-10-22  9:45   ` Jan Kara
2015-10-22 15:41     ` Dan Williams
2015-10-22  6:42 ` [PATCH 5/5] block: enable dax for raw block devices Dan Williams
2015-10-22  9:35   ` Jan Kara
2015-10-22 16:05     ` Williams, Dan J
2015-10-22 21:08       ` Jan Kara
2015-10-22 23:41         ` Williams, Dan J
2015-10-24 12:21           ` Jan Kara
2015-10-23 23:32         ` Dan Williams
2015-10-24 14:49           ` Jan Kara
2015-10-25 21:22         ` Dave Chinner [this message]
2015-10-26  2:48           ` Dan Williams
2015-10-26  6:23             ` Dave Chinner
2015-10-26  7:20               ` Jan Kara
2015-10-26  8:56               ` Dan Williams
2015-10-26 22:19                 ` Dave Chinner
2015-10-27 22:55                   ` Ross Zwisler

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