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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 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax()
Date: Tue, 11 Feb 2020 08:13:49 -0800
Message-ID: <20200211161348.GA12866@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200211054748.GF10776@dread.disaster.area>

On Tue, Feb 11, 2020 at 04:47:48PM +1100, Dave Chinner wrote:
> On Sat, Feb 08, 2020 at 11:34:36AM -0800, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> > 

[snip]

> >  
> > +static bool
> > +xfs_inode_is_dax(
> > +	struct xfs_inode *ip)
> > +{
> > +	return (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX) == XFS_DIFLAG2_DAX;
> > +}
> 
> I don't think these wrappers add any value at all - the naming of
> them is entirely confusing, too. e.g. "inode is dax" doesn't tell me
> that it is checking the on disk flags - it doesn't tell me how it is
> different to IS_DAX, or why I'd use one versus the other. And then
> xfs_inode_mount_is_dax() is just... worse.
> 
> Naming is hard. :)

Sure...  I'm particularly bad as well...

FWIW I don't see how xfs_inode_mount_is_dax() is worse, I rather think that is
pretty clear but I'm not going to quibble over names because I know I'm rubbish
at it and I'm certainly not enough of a FS person to make them clear...  ;-)

> 
> > +
> > +static bool
> > +xfs_inode_use_dax(
> > +	struct xfs_inode *ip)
> > +{
> > +	return xfs_inode_supports_dax(ip) &&
> > +		(xfs_inode_mount_is_dax(ip) ||
> > +		 xfs_inode_is_dax(ip));
> > +}
> 
> Urk. Naming - we're not "using dax" here, we are checkign to see if
> we should enable DAX on this inode. IOWs:

Well just to defend myself a little bit.  My thought was:

"When setting i_flags, should I use dax?"

> 
> static bool
> xfs_inode_enable_dax(
> 	struct xfs_inode *ip)
> {
> 	if (!xfs_inode_supports_dax(ip))
> 		return false;
> 
> 	if (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX)
> 		return true;
> 	if (ip->i_mount->m_flags & XFS_MOUNT_DAX)
> 		return true;
> 	return false;
> }

Anyway, I'm good with this.

Changed for V4.

Thanks!
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 [this message]
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
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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