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From: Dave Chinner <david@fromorbit.com>
To: ira.weiny@intel.com
Cc: linux-kernel@vger.kernel.org,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Christoph Hellwig <hch@lst.de>,
	"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
	linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/5] fs/xfs: Isolate the physical DAX flag from effective
Date: Mon, 21 Oct 2019 11:26:21 +1100	[thread overview]
Message-ID: <20191021002621.GC8015@dread.disaster.area> (raw)
In-Reply-To: <20191020155935.12297-3-ira.weiny@intel.com>

On Sun, Oct 20, 2019 at 08:59:32AM -0700, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
> 
> xfs_ioctl_setattr_dax_invalidate() currently checks if the DAX flag is
> changing as a quick check.
> 
> But the implementation mixes the physical (XFS_DIFLAG2_DAX) and
> effective (S_DAX) DAX flags.

More nuanced than that.

The idea was that if the mount option was set, clearing the
per-inode flag would override the mount option. i.e. the mount
option sets the S_DAX flag at inode instantiation, so using
FSSETXATTR to ensure the FS_XFLAG_DAX is not set would override the
mount option setting, giving applications a way of guranteeing they
aren't using DAX to access the data.

So if the mount option is going to live on, I suspect that we want
to keep this code as it stands.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  reply	other threads:[~2019-10-21  0:26 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-20 15:59 [PATCH 0/5] Enable per-file/directory DAX operations ira.weiny
2019-10-20 15:59 ` [PATCH 1/5] fs/stat: Define DAX statx attribute ira.weiny
2019-10-22 11:32   ` Boaz Harrosh
2019-10-22 16:51     ` Ira Weiny
2019-10-20 15:59 ` [PATCH 2/5] fs/xfs: Isolate the physical DAX flag from effective ira.weiny
2019-10-21  0:26   ` Dave Chinner [this message]
2019-10-21 17:40     ` Ira Weiny
2019-10-20 15:59 ` [PATCH 3/5] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny
2019-10-20 15:59 ` [PATCH 4/5] fs/xfs: Clean up DAX support check ira.weiny
2019-10-20 15:59 ` [PATCH 5/5] fs/xfs: Allow toggle of physical DAX flag ira.weiny
2019-10-21  0:45   ` Dave Chinner
2019-10-21 22:49     ` Ira Weiny
2019-10-21 23:46       ` Dave Chinner
2019-11-08 13:12       ` Jan Kara
2019-11-08 13:46         ` Jan Kara
2019-11-08 19:36           ` Ira Weiny
2019-11-11 16:07             ` Jan Kara
2019-11-11 23:54               ` Ira Weiny
2019-10-22 11:21 ` [PATCH 0/5] Enable per-file/directory DAX operations Boaz Harrosh
2019-10-23 13:09   ` Boaz Harrosh
2019-10-23 22:13     ` Dave Chinner
2019-10-24  2:31       ` Boaz Harrosh
2019-10-24  7:34         ` Dave Chinner
2019-10-24 14:05           ` Boaz Harrosh
2019-10-24 21:35             ` Dave Chinner
2019-10-24 23:29               ` Boaz Harrosh
2019-10-25  0:36                 ` Dave Chinner
2019-10-25  1:15                   ` Boaz Harrosh
2019-10-25 20:49                   ` Ira Weiny
2019-10-27 22:10                     ` Dave Chinner
2019-10-31 16:17                       ` Ira Weiny
2019-11-01 22:47                         ` Dave Chinner
2019-11-02  4:25                           ` Dan Williams

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