From: Jan Kara <jack@suse.cz>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dave Chinner <david@fromorbit.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Andreas Dilger <adilger@dilger.ca>,
Dan Williams <dan.j.williams@intel.com>,
Eric Sandeen <sandeen@redhat.com>,
Lukas Czerner <lczerner@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Christoph Hellwig <hch@lst.de>, Jan Kara <jack@suse.cz>,
linux-ext4 <linux-ext4@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
xfs <linux-xfs@vger.kernel.org>
Subject: Re: [PATCH 0/9] add ext4 per-inode DAX flag
Date: Mon, 11 Sep 2017 10:47:33 +0200 [thread overview]
Message-ID: <20170911084733.GB7120@quack2.suse.cz> (raw)
In-Reply-To: <20170908153913.jjhzogjs5zpeea5v@thunk.org>
On Fri 08-09-17 11:39:13, Ted Tso wrote:
> On Fri, Sep 08, 2017 at 09:25:43AM +1000, Dave Chinner wrote:
> > > Okay, so other ideas (which you have also probably already though of) include:
> > >
> > > 1) Just return -EBUSY if anyone tries to change the DAX flag of an inode with
> > > open mappings or any open file handles.
> >
> > You have to have an open fd to change the flag. :)
>
> What if we only allow the S_DAX flag to be *set*, when i_size and
> i_blocks is zero? We could also require that only one file descriptor
> be open against the inode, and that it be opened O_RDONLY.
We could do something like that but IMHO it will be a pain to use (e.g.
think how difficult it would be to switch your existing database to use DAX
for data files). We can make transition reliable whenever
inode->i_mapping->i_mmap RB tree is empty (effectively: whenever the file
is not mmaped). And that should be relaxed enough for most usecases... But
I agree that it will be somewhat tricky to prevent creation of new mappings
while we are switching S_DAX flag so it needs more though.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
prev parent reply other threads:[~2017-09-11 8:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-05 22:35 [PATCH 0/9] add ext4 per-inode DAX flag Ross Zwisler
2017-09-05 22:35 ` [PATCH 1/9] ext4: remove duplicate extended attributes defs Ross Zwisler
2017-09-06 7:29 ` Jan Kara
2017-09-05 22:35 ` [PATCH 2/9] xfs: always use DAX if mount option is used Ross Zwisler
2017-09-05 22:35 ` [PATCH 3/9] xfs: validate bdev support for DAX inode flag Ross Zwisler
2017-09-05 22:35 ` [PATCH 4/9] ext4: add ext4_should_use_dax() Ross Zwisler
2017-09-05 22:35 ` [PATCH 5/9] ext4: ext4_change_inode_journal_flag error handling Ross Zwisler
2017-09-05 22:35 ` [PATCH 6/9] ext4: safely transition S_DAX on journaling changes Ross Zwisler
2017-09-06 9:47 ` Jan Kara
2017-09-06 17:09 ` Ross Zwisler
2017-09-05 22:35 ` [PATCH 7/9] ext4: prevent data corruption with inline data + DAX Ross Zwisler
2017-09-06 20:55 ` Andreas Dilger
2017-09-06 23:11 ` Ross Zwisler
2017-09-05 22:35 ` [PATCH 8/9] ext4: add sanity check for encryption " Ross Zwisler
2017-09-05 22:35 ` [PATCH 9/9] ext4: add per-inode DAX flag Ross Zwisler
2017-09-06 2:12 ` [PATCH 0/9] add ext4 " Eric Sandeen
2017-09-06 17:07 ` Ross Zwisler
2017-09-07 20:54 ` Dan Williams
2017-09-07 21:13 ` Ross Zwisler
2017-09-07 21:26 ` Andreas Dilger
2017-09-07 21:51 ` Ross Zwisler
2017-09-07 22:12 ` Dave Chinner
2017-09-07 22:19 ` Ross Zwisler
2017-09-07 23:25 ` Dave Chinner
2017-09-08 9:48 ` Jan Kara
2017-09-08 15:39 ` Theodore Ts'o
2017-09-11 8:47 ` Jan Kara [this message]
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