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From: Ira Weiny <ira.weiny@intel.com>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	Dave Chinner <david@fromorbit.com>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	Dan Williams <dan.j.williams@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH V5 00/12] Enable per-file/per-directory DAX operations V5
Date: Fri, 3 Apr 2020 11:21:20 -0700
Message-ID: <20200403182119.GL3952565@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200403181843.GK3952565@iweiny-DESK2.sc.intel.com>

On Fri, Apr 03, 2020 at 11:18:43AM -0700, 'Ira Weiny' wrote:
[snip]

> 
> Ok For 5.8 why don't we not allow FS_XFLAG_DAX to be changed on files _at_
> _all_...

To be fair, I believe Christoph advocated for this at one time or another...

Ira

> 
> In summary:
> 
>  - Applications must call statx to discover the current S_DAX state.
> 
>  - There exists an advisory file inode flag FS_XFLAG_DAX that is set based on
>    the parent directory FS_XFLAG_DAX inode flag.  (There is no way to change
>    this flag after file creation.)
> 
>    If FS_XFLAG_DAX is set and the fs is on pmem then it will enable S_DAX at
>    inode load time; if FS_XFLAG_DAX is not set, it will not enable S_DAX.
>    Unless overridden...
> 
>  - There exists a dax= mount option.
> 
>    "-o dax=off" means "never set S_DAX, ignore FS_XFLAG_DAX"
>    	"-o nodax" means "dax=off"
>    "-o dax=always" means "always set S_DAX (at least on pmem), ignore FS_XFLAG_DAX"
>    	"-o dax" by itself means "dax=always"
>    "-o dax=iflag" means "follow FS_XFLAG_DAX" and is the default
> 
>  - There exists an advisory directory inode flag FS_XFLAG_DAX that can be
>    changed at any time.  The flag state is copied into any files or
>    subdirectories when they are created within that directory.  If programs
>    require file access runs in S_DAX mode, they'll have to create those files
>    inside a directory with FS_XFLAG_DAX set, or mount the fs with an
>    appropriate dax mount option.
> 
> 
> ???
> 
> Ira
> 

  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-27  5:24 ira.weiny
2020-02-27  5:24 ` [PATCH V5 01/12] fs/xfs: Remove unnecessary initialization of i_rwsem ira.weiny
2020-02-27 17:25   ` Ira Weiny
2020-02-27  5:24 ` [PATCH V5 02/12] fs: Remove unneeded IS_DAX() check ira.weiny
2020-02-27  5:24 ` [PATCH V5 03/12] fs/stat: Define DAX statx attribute ira.weiny
2020-02-27  5:24 ` [PATCH V5 04/12] fs/xfs: Isolate the physical DAX flag from enabled ira.weiny
2020-02-27  5:24 ` [PATCH V5 05/12] fs/xfs: Create function xfs_inode_enable_dax() ira.weiny
2020-03-01 22:37   ` Dave Chinner
2020-02-27  5:24 ` [PATCH V5 06/12] fs: Add locking for a dynamic address space operations state ira.weiny
2020-03-02  1:26   ` Dave Chinner
2020-03-02  1:36     ` Dave Chinner
2020-02-27  5:24 ` [PATCH V5 07/12] fs: Prevent DAX state change if file is mmap'ed ira.weiny
2020-02-27  5:24 ` [PATCH V5 08/12] fs/xfs: Hold off aops users while changing DAX state ira.weiny
2020-02-27  5:24 ` [PATCH V5 09/12] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-02-27  5:24 ` [PATCH V5 10/12] fs/xfs: Allow toggle of effective DAX flag ira.weiny
2020-02-27  5:24 ` [PATCH V5 11/12] fs/xfs: Remove xfs_diflags_to_linux() ira.weiny
2020-02-27  5:24 ` [PATCH V5 12/12] Documentation/dax: Update Usage section ira.weiny
2020-03-05 15:51 ` [PATCH V5 00/12] Enable per-file/per-directory DAX operations V5 Christoph Hellwig
2020-03-09 17:04   ` Ira Weiny
2020-03-11  3:36     ` Darrick J. Wong
2020-03-11  6:29       ` Christoph Hellwig
2020-03-11 17:07         ` Dan Williams
2020-03-16  9:52           ` Jan Kara
2020-03-16  9:55             ` Christoph Hellwig
2020-04-01  4:00               ` Darrick J. Wong
2020-04-01 10:25                 ` Jan Kara
2020-04-02  8:53                   ` Christoph Hellwig
2020-04-02 20:55                     ` Ira Weiny
2020-04-03  7:27                       ` Christoph Hellwig
2020-04-03 15:48                         ` Ira Weiny
2020-04-03 17:03                           ` Jan Kara
2020-04-03 18:18                             ` Ira Weiny
2020-04-03 18:21                               ` Ira Weiny [this message]
2020-04-03 18:37                               ` Darrick J. Wong
2020-04-05  6:19                                 ` Ira Weiny
2020-04-06 10:00                               ` Jan Kara
2020-04-03 18:29                             ` Darrick J. Wong
2020-04-03 16:05                         ` Darrick J. Wong
2020-04-03  4:39                 ` Ira Weiny
2020-03-11  6:39       ` Dave Chinner
2020-03-11  6:44         ` Christoph Hellwig
2020-03-11 17:07           ` Dan Williams
2020-03-12  0:49           ` Dave Chinner
2020-03-12  3:00             ` Darrick J. Wong
2020-03-12  7:27             ` Christoph Hellwig

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