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From: Ira Weiny <ira.weiny@intel.com>
To: Dave Chinner <david@fromorbit.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 v3 04/12] fs/xfs: Clean up DAX support check
Date: Tue, 11 Feb 2020 08:28:30 -0800
Message-ID: <20200211162830.GB12866@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200211055745.GG10776@dread.disaster.area>

On Tue, Feb 11, 2020 at 04:57:45PM +1100, Dave Chinner wrote:
> On Sat, Feb 08, 2020 at 11:34:37AM -0800, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 
> > Rather than open coding xfs_inode_supports_dax() in
> > xfs_ioctl_setattr_dax_invalidate() export xfs_inode_supports_dax() and
> > call it in preparation for swapping dax flags.
> > 
> > This also means updating xfs_inode_supports_dax() to return true for a
> > directory.
> 
> That's not correct. This now means S_DAX gets set on directory inodes
> because both xfs_inode_supports_dax() and the on-disk inode flag
> checks return true in xfs_diflags_to_iflags(). Hence when we
> instantiate a directory inode with a DAX inherit hint set on it
> we'll set S_DAX on the inode and so IS_DAX() will return true for
> directory inodes...

I'm not following.  Don't we want S_DAX to get set on directory inodes?

IIRC what we wanted was something like this where IS_DAX is the current state
and "dax" is the inode flag:

/ <IS_DAX=0 dax=0>
	dir1 <IS_DAX=0 dax=0>
		f0 <IS_DAX=0 dax=0>
		f1 <IS_DAX=1 dax=1>
	dir2 <IS_DAX=1 dax=1>
		f2 <IS_DAX=1 dax=1>
		f3 <IS_DAX=0 dax=0>
		dir3 <IS_DAX=1 dax=1>
			f4 <IS_DAX=1 dax=1>
		dir4 <IS_DAX=0 dax=0>
			f5 <IS_DAX=0 dax=0>
		f6 <IS_DAX=1 dax=1>

Where f1, dir2, f3, and dir4 required explicit state changes when they were
created.  Because they inherited their dax state from the parent.  All the
other creations happened based on the DAX state of the parent directory.  So we
need to store and know the state of the directories.  What am I missing?

Ira

> 
> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.com

  reply index

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-08 19:34 [PATCH v3 00/12] Enable per-file/directory DAX operations V3 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 [this message]
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
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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