From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Jeff Layton <jlayton@poochiereds.net>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org,
"J. Bruce Fields" <bfields@fieldses.org>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-xfs@vger.kernel.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 1/7] xfs: always use DAX if mount option is used
Date: Tue, 26 Sep 2017 12:50:08 -0600 [thread overview]
Message-ID: <20170926185008.GA31146@linux.intel.com> (raw)
In-Reply-To: <20170925233812.GM10955@dastard>
On Tue, Sep 26, 2017 at 09:38:12AM +1000, Dave Chinner wrote:
> On Mon, Sep 25, 2017 at 05:13:58PM -0600, Ross Zwisler wrote:
> > Before support for the per-inode DAX flag was disabled the XFS the code had
> > an issue where the user couldn't reliably tell whether or not DAX was being
> > used to service page faults and I/O when the DAX mount option was used. In
> > this case each inode within the mounted filesystem started with S_DAX set
> > due to the mount option, but it could be cleared if someone touched the
> > individual inode flag.
> >
> > For example (v4.13 and before):
> >
> > # mount | grep dax
> > /dev/pmem0 on /mnt type xfs
> > (rw,relatime,seclabel,attr2,dax,inode64,sunit=4096,swidth=4096,noquota)
> >
> > # touch /mnt/a /mnt/b # both files currently use DAX
> >
> > # xfs_io -c "lsattr" /mnt/* # neither has the DAX inode option set
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
> >
> > # xfs_io -c "chattr -x" /mnt/a # this clears S_DAX for /mnt/a
> >
> > # xfs_io -c "lsattr" /mnt/*
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
>
> That's really a bug in the lsattr code, yes? If we've cleared the
> S_DAX flag for the inode, then why is it being reported in lsattr?
> Or if we failed to clear the S_DAX flag in the 'chattr -x' call,
> then isn't that the bug that needs fixing?
No, I think lsattr/chattr are working correctly. In both the examples above
the DAX inode flag (which is represeted by an 'x') is never set. S_DAX is the
in-memory inode flag (not the on-media inode flag) which is not manipulated
directly by lsattr/chattr, but instead reflects whether the inode is actually
using DAX or not.
Manipulating and displaying the on-media inode flag works as expected with
lsattr/chattr:
# xfs_io -c "lsattr" ./a
---------------- ./a
# xfs_io -c "chattr +x" ./a
# xfs_io -c "lsattr" ./a
--------------x- ./a
- Ross
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"Darrick J. Wong" <darrick.wong@oracle.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
Christoph Hellwig <hch@lst.de>,
Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@poochiereds.net>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/7] xfs: always use DAX if mount option is used
Date: Tue, 26 Sep 2017 12:50:08 -0600 [thread overview]
Message-ID: <20170926185008.GA31146@linux.intel.com> (raw)
In-Reply-To: <20170925233812.GM10955@dastard>
On Tue, Sep 26, 2017 at 09:38:12AM +1000, Dave Chinner wrote:
> On Mon, Sep 25, 2017 at 05:13:58PM -0600, Ross Zwisler wrote:
> > Before support for the per-inode DAX flag was disabled the XFS the code had
> > an issue where the user couldn't reliably tell whether or not DAX was being
> > used to service page faults and I/O when the DAX mount option was used. In
> > this case each inode within the mounted filesystem started with S_DAX set
> > due to the mount option, but it could be cleared if someone touched the
> > individual inode flag.
> >
> > For example (v4.13 and before):
> >
> > # mount | grep dax
> > /dev/pmem0 on /mnt type xfs
> > (rw,relatime,seclabel,attr2,dax,inode64,sunit=4096,swidth=4096,noquota)
> >
> > # touch /mnt/a /mnt/b # both files currently use DAX
> >
> > # xfs_io -c "lsattr" /mnt/* # neither has the DAX inode option set
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
> >
> > # xfs_io -c "chattr -x" /mnt/a # this clears S_DAX for /mnt/a
> >
> > # xfs_io -c "lsattr" /mnt/*
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
>
> That's really a bug in the lsattr code, yes? If we've cleared the
> S_DAX flag for the inode, then why is it being reported in lsattr?
> Or if we failed to clear the S_DAX flag in the 'chattr -x' call,
> then isn't that the bug that needs fixing?
No, I think lsattr/chattr are working correctly. In both the examples above
the DAX inode flag (which is represeted by an 'x') is never set. S_DAX is the
in-memory inode flag (not the on-media inode flag) which is not manipulated
directly by lsattr/chattr, but instead reflects whether the inode is actually
using DAX or not.
Manipulating and displaying the on-media inode flag works as expected with
lsattr/chattr:
# xfs_io -c "lsattr" ./a
---------------- ./a
# xfs_io -c "chattr +x" ./a
# xfs_io -c "lsattr" ./a
--------------x- ./a
- Ross
WARNING: multiple messages have this Message-ID (diff)
From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"Darrick J. Wong" <darrick.wong@oracle.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
Christoph Hellwig <hch@lst.de>,
Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@poochiereds.net>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/7] xfs: always use DAX if mount option is used
Date: Tue, 26 Sep 2017 12:50:08 -0600 [thread overview]
Message-ID: <20170926185008.GA31146@linux.intel.com> (raw)
In-Reply-To: <20170925233812.GM10955@dastard>
On Tue, Sep 26, 2017 at 09:38:12AM +1000, Dave Chinner wrote:
> On Mon, Sep 25, 2017 at 05:13:58PM -0600, Ross Zwisler wrote:
> > Before support for the per-inode DAX flag was disabled the XFS the code had
> > an issue where the user couldn't reliably tell whether or not DAX was being
> > used to service page faults and I/O when the DAX mount option was used. In
> > this case each inode within the mounted filesystem started with S_DAX set
> > due to the mount option, but it could be cleared if someone touched the
> > individual inode flag.
> >
> > For example (v4.13 and before):
> >
> > # mount | grep dax
> > /dev/pmem0 on /mnt type xfs
> > (rw,relatime,seclabel,attr2,dax,inode64,sunit=4096,swidth=4096,noquota)
> >
> > # touch /mnt/a /mnt/b # both files currently use DAX
> >
> > # xfs_io -c "lsattr" /mnt/* # neither has the DAX inode option set
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
> >
> > # xfs_io -c "chattr -x" /mnt/a # this clears S_DAX for /mnt/a
> >
> > # xfs_io -c "lsattr" /mnt/*
> > ----------e----- /mnt/a
> > ----------e----- /mnt/b
>
> That's really a bug in the lsattr code, yes? If we've cleared the
> S_DAX flag for the inode, then why is it being reported in lsattr?
> Or if we failed to clear the S_DAX flag in the 'chattr -x' call,
> then isn't that the bug that needs fixing?
No, I think lsattr/chattr are working correctly. In both the examples above
the DAX inode flag (which is represeted by an 'x') is never set. S_DAX is the
in-memory inode flag (not the on-media inode flag) which is not manipulated
directly by lsattr/chattr, but instead reflects whether the inode is actually
using DAX or not.
Manipulating and displaying the on-media inode flag works as expected with
lsattr/chattr:
# xfs_io -c "lsattr" ./a
---------------- ./a
# xfs_io -c "chattr +x" ./a
# xfs_io -c "lsattr" ./a
--------------x- ./a
- Ross
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next prev parent reply other threads:[~2017-09-26 18:46 UTC|newest]
Thread overview: 130+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 23:13 [PATCH 0/7] re-enable XFS per-inode DAX Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-25 23:13 ` [PATCH 1/7] xfs: always use DAX if mount option is used Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-25 23:38 ` Dave Chinner
2017-09-25 23:38 ` Dave Chinner
2017-09-25 23:38 ` Dave Chinner
2017-09-26 9:35 ` Jan Kara
2017-09-26 9:35 ` Jan Kara
2017-09-26 9:35 ` Jan Kara
2017-09-26 11:09 ` Dave Chinner
2017-09-26 11:09 ` Dave Chinner
2017-09-26 11:09 ` Dave Chinner
2017-09-26 14:37 ` Christoph Hellwig
2017-09-26 14:37 ` Christoph Hellwig
2017-09-26 17:30 ` Ross Zwisler
2017-09-26 17:30 ` Ross Zwisler
2017-09-26 17:30 ` Ross Zwisler
2017-09-26 19:48 ` Darrick J. Wong
2017-09-26 19:48 ` Darrick J. Wong
2017-09-26 22:00 ` Dave Chinner
2017-09-26 22:00 ` Dave Chinner
2017-09-26 22:00 ` Dave Chinner
2017-09-27 6:40 ` Christoph Hellwig
2017-09-27 6:40 ` Christoph Hellwig
2017-09-27 6:40 ` Christoph Hellwig
2017-09-27 16:15 ` Ross Zwisler
2017-09-27 16:15 ` Ross Zwisler
2017-10-01 8:17 ` Christoph Hellwig
2017-10-01 8:17 ` Christoph Hellwig
2017-10-01 8:17 ` Christoph Hellwig
2017-09-26 18:02 ` Eric Sandeen
2017-09-26 18:02 ` Eric Sandeen
2017-09-26 18:02 ` Eric Sandeen
2017-09-26 18:50 ` Ross Zwisler [this message]
2017-09-26 18:50 ` Ross Zwisler
2017-09-26 18:50 ` Ross Zwisler
2017-09-25 23:13 ` [PATCH 2/7] xfs: validate bdev support for DAX inode flag Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-25 23:13 ` Ross Zwisler
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 17:16 ` Ross Zwisler
2017-09-26 17:16 ` Ross Zwisler
2017-09-26 17:16 ` Ross Zwisler
2017-09-26 17:57 ` Darrick J. Wong
2017-09-26 17:57 ` Darrick J. Wong
2017-09-25 23:14 ` [PATCH 3/7] xfs: protect S_DAX transitions in XFS read path Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:27 ` Dave Chinner
2017-09-25 23:27 ` Dave Chinner
2017-09-25 23:27 ` Dave Chinner
2017-09-26 6:32 ` Christoph Hellwig
2017-09-26 6:32 ` Christoph Hellwig
2017-09-26 6:32 ` Christoph Hellwig
2017-09-26 13:59 ` Dan Williams
2017-09-26 13:59 ` Dan Williams
2017-09-26 13:59 ` Dan Williams
2017-09-26 14:33 ` Christoph Hellwig
2017-09-26 14:33 ` Christoph Hellwig
2017-09-26 14:33 ` Christoph Hellwig
2017-09-26 18:11 ` Dan Williams
2017-09-26 18:11 ` Dan Williams
2017-10-01 8:17 ` Christoph Hellwig
2017-10-01 8:17 ` Christoph Hellwig
2017-10-01 8:17 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 4/7] xfs: protect S_DAX transitions in XFS write path Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:29 ` Dave Chinner
2017-09-25 23:29 ` Dave Chinner
2017-09-25 23:29 ` Dave Chinner
2017-09-25 23:14 ` [PATCH 5/7] xfs: introduce xfs_is_dax_state_changing Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-26 6:33 ` Christoph Hellwig
2017-09-26 6:33 ` Christoph Hellwig
2017-09-26 6:33 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 6/7] mm, fs: introduce file_operations->post_mmap() Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:38 ` Dan Williams
2017-09-25 23:38 ` Dan Williams
2017-09-26 18:57 ` Ross Zwisler
2017-09-26 18:57 ` Ross Zwisler
2017-09-26 18:57 ` Ross Zwisler
2017-09-26 19:19 ` Dan Williams
2017-09-26 19:19 ` Dan Williams
2017-09-26 19:19 ` Dan Williams
2017-09-26 21:06 ` Ross Zwisler
2017-09-26 21:06 ` Ross Zwisler
2017-09-26 21:06 ` Ross Zwisler
2017-09-26 21:41 ` Dan Williams
2017-09-26 21:41 ` Dan Williams
2017-09-26 21:41 ` Dan Williams
2017-09-27 11:35 ` Jan Kara
2017-09-27 11:35 ` Jan Kara
2017-09-27 11:35 ` Jan Kara
2017-09-27 14:00 ` Dan Williams
2017-09-27 14:00 ` Dan Williams
2017-09-27 14:00 ` Dan Williams
2017-09-27 15:07 ` Jan Kara
2017-09-27 15:07 ` Jan Kara
2017-09-27 15:07 ` Jan Kara
2017-09-27 15:36 ` Dan Williams
2017-09-27 15:36 ` Dan Williams
2017-09-27 15:39 ` Ross Zwisler
2017-09-27 15:39 ` Ross Zwisler
2017-09-27 15:39 ` Ross Zwisler
2017-09-27 15:54 ` Dan Williams
2017-09-27 15:54 ` Dan Williams
2017-09-27 15:54 ` Dan Williams
2017-09-26 6:34 ` Christoph Hellwig
2017-09-26 6:34 ` Christoph Hellwig
2017-09-26 6:34 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 7/7] xfs: re-enable XFS per-inode DAX Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-25 23:14 ` Ross Zwisler
2017-09-26 0:31 ` Dave Chinner
2017-09-26 0:31 ` Dave Chinner
2017-09-26 0:31 ` Dave Chinner
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 19:01 ` Ross Zwisler
2017-09-26 19:01 ` Ross Zwisler
2017-09-26 19:01 ` Ross Zwisler
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