From: Jeff Moyer <jmoyer@redhat.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@lst.de>,
"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
linux-ext4 <linux-ext4@vger.kernel.org>,
linux-xfs <linux-xfs@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v3 00/12] Enable per-file/directory DAX operations V3
Date: Fri, 14 Feb 2020 16:23:19 -0500
Message-ID: <x4936bcdfso.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <20200214200607.GA18593@iweiny-DESK2.sc.intel.com> (Ira Weiny's message of "Fri, 14 Feb 2020 12:06:07 -0800")
Ira Weiny <ira.weiny@intel.com> writes:
> [disclaimer: the following assumes the underlying 'device' (superblock)
> supports DAX]
>
> ... which results in S_DAX == false when the file is opened without the mount
> option. The key would be that all directories/files created under a root with
> XFS_DIFLAG2_DAX == true would inherit their flag and be XFS_DIFLAG2_DAX == true
> all the way down the tree. Any file not wanting DAX would need to set
> XFS_DIFLAG2_DAX == false. And setting false could be used on a directory to
> allow a user or group to not use dax on files in that sub-tree.
>
> Then without '-o dax' (XFS_MOUNT_DAX == false) all files when opened set S_DAX
> equal to XFS_DIFLAG2_DAX value. (Directories, as of V4, never get S_DAX set.)
>
> If '-o dax' (XFS_MOUNT_DAX == true) then S_DAX is set on all files.
One more clarifying question. Let's say I set XFS_DIFLAG2_DAX on an
inode. I then open the file, and perform mmap/load/store/etc. I close
the file, and I unset XFS_DIFLAG2_DAX. Will the next open treat the
file as S_DAX or not? My guess is the inode won't be evicted, and so
S_DAX will remain set.
The reason I ask is I've had requests from application developers to do
just this. They want to be able to switch back and forth between dax
modes.
Thanks,
Jeff
> [1] I'm beginning to think that if I type dax one more time I'm going to go
> crazy... :-P
dax dax dax!
next prev parent reply index
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-08 19:34 ira.weiny
2020-02-08 19:34 ` [PATCH v3 01/12] fs/stat: Define DAX statx attribute ira.weiny
2020-02-08 19:34 ` [PATCH v3 02/12] fs/xfs: Isolate the physical DAX flag from effective ira.weiny
2020-02-08 19:34 ` [PATCH v3 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny
2020-02-11 5:47 ` Dave Chinner
2020-02-11 16:13 ` Ira Weiny
2020-02-08 19:34 ` [PATCH v3 04/12] fs/xfs: Clean up DAX support check ira.weiny
2020-02-11 5:57 ` Dave Chinner
2020-02-11 16:28 ` Ira Weiny
2020-02-11 20:38 ` Dave Chinner
2020-02-08 19:34 ` [PATCH v3 05/12] fs: remove unneeded IS_DAX() check ira.weiny
2020-02-11 5:34 ` Dave Chinner
2020-02-11 16:38 ` Ira Weiny
2020-02-11 20:41 ` Dave Chinner
2020-02-12 16:04 ` Ira Weiny
2020-02-08 19:34 ` [PATCH v3 06/12] fs/xfs: Check if the inode supports DAX under lock ira.weiny
2020-02-11 6:16 ` Dave Chinner
2020-02-11 17:55 ` Ira Weiny
2020-02-11 20:42 ` Dave Chinner
2020-02-12 16:10 ` Ira Weiny
2020-02-08 19:34 ` [PATCH v3 07/12] fs: Add locking for a dynamic DAX state ira.weiny
2020-02-11 8:00 ` Dave Chinner
2020-02-11 20:14 ` Ira Weiny
2020-02-11 20:59 ` Dan Williams
2020-02-11 21:49 ` Dave Chinner
2020-02-12 6:31 ` Darrick J. Wong
2020-02-08 19:34 ` [PATCH v3 08/12] fs/xfs: Clarify lockdep dependency for xfs_isilocked() ira.weiny
2020-02-08 19:34 ` [PATCH v3 09/12] fs/xfs: Add write DAX lock to xfs layer ira.weiny
2020-02-08 19:34 ` [PATCH v3 10/12] fs: Prevent DAX state change if file is mmap'ed ira.weiny
2020-02-08 19:34 ` [PATCH v3 11/12] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-02-08 19:34 ` [PATCH v3 12/12] fs/xfs: Allow toggle of effective DAX flag ira.weiny
2020-02-10 15:15 ` [PATCH v3 00/12] Enable per-file/directory DAX operations V3 Jeff Moyer
2020-02-11 20:17 ` Ira Weiny
2020-02-12 19:49 ` Jeff Moyer
2020-02-13 19:01 ` Ira Weiny
2020-02-13 19:05 ` Ira Weiny
2020-02-13 19:58 ` Darrick J. Wong
2020-02-13 23:29 ` Ira Weiny
2020-02-14 0:16 ` Dan Williams
2020-02-14 20:06 ` Ira Weiny
2020-02-14 21:23 ` Jeff Moyer [this message]
2020-02-14 21:58 ` Ira Weiny
2020-02-14 22:06 ` Jeff Moyer
2020-02-14 22:58 ` Jeff Moyer
2020-02-14 23:03 ` Jeff Moyer
2020-02-18 2:35 ` Ira Weiny
2020-02-18 14:22 ` Jeff Moyer
2020-02-18 23:54 ` Ira Weiny
2020-02-20 16:20 ` Ira Weiny
2020-02-20 16:30 ` Darrick J. Wong
2020-02-20 16:49 ` Ira Weiny
2020-02-20 17:00 ` Darrick J. Wong
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