From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>,
linux-kernel@vger.kernel.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.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 00/12] Enable per-file/directory DAX operations V3
Date: Thu, 13 Feb 2020 11:58:39 -0800 [thread overview]
Message-ID: <20200213195839.GG6870@magnolia> (raw)
In-Reply-To: <20200213190513.GB22854@iweiny-DESK2.sc.intel.com>
On Thu, Feb 13, 2020 at 11:05:13AM -0800, Ira Weiny wrote:
> On Thu, Feb 13, 2020 at 11:01:57AM -0800, 'Ira Weiny' wrote:
> > On Wed, Feb 12, 2020 at 02:49:48PM -0500, Jeff Moyer wrote:
> > > Ira Weiny <ira.weiny@intel.com> writes:
> > >
>
> [snip]
>
> > > Given that we document the dax mount
> > > option as "the way to get dax," it may be a good idea to allow for a
> > > user to selectively disable dax, even when -o dax is specified. Is that
> > > possible?
> >
> > Not with this patch set. And I'm not sure how that would work. The idea was
> > that -o dax was simply an override for users who were used to having their
> > entire FS be dax. We wanted to depreciate the use of "-o dax" in general. The
> > individual settings are saved so I don't think it makes sense to ignore the -o
> > dax in favor of those settings. Basically that would IMO make the -o dax
> > useless.
>
> Oh and I forgot to mention that setting 'dax' on the root of the FS basically
> provides '-o dax' functionality by default with the ability to "turn it off"
> for files.
Please don't further confuse FS_XFLAG_DAX and S_DAX. They are two
separate flags with two separate behaviors:
FS_XFLAG_DAX is a filesystem inode metadata flag.
Setting FS_XFLAG_DAX on a directory causes all files and directories
created within that directory to inherit FS_XFLAG_DAX.
Mounting with -o dax causes all files and directories created to have
FS_XFLAG_DAX set regardless of the parent's status.
The FS_XFLAG_DAX can be get and set via the fs[g]etxattr ioctl.
-------
S_DAX is the flag that controls the IO path in the kernel for a given
inode.
Loading a file inode into the kernel (via _iget) with FS_XFLAG_DAX set
or creating a file inode that inherits FS_XFLAG_DAX causes the incore
inode to have the S_DAX flag set if the storage device supports it.
Files with S_DAX set use the dax IO paths through the kernel.
The S_DAX flag can be queried via statx.
--D
> Ira
>
> >
> > Ira
> >
next prev parent reply other threads:[~2020-02-13 20:01 UTC|newest]
Thread overview: 53+ 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
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
2020-02-11 17:51 ` kbuild test robot
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 [this message]
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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