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From: Ross Zwisler <ross.zwisler@linux.intel.com>
To: Toshi Kani <toshi.kani@hpe.com>,
	Mike Snitzer <snitzer@redhat.com>,
	dm-devel@redhat.com
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org
Subject: [PATCH resend 0/7] Fix DM DAX handling
Date: Fri, 25 May 2018 16:00:48 -0600	[thread overview]
Message-ID: <20180525220055.18920-1-ross.zwisler@linux.intel.com> (raw)

No code changes from v1.  Just CCing the xfs mailing list & adding one
Reviewed-by from Darrick.

---

This series fixes a few issues that I found with DM's handling of DAX
devices.  Here are some of the issues I found:

 * We can create a dm-stripe or dm-linear device which is made up of an
   fsdax PMEM namespace and a raw PMEM namespace but which can hold a
   filesystem mounted with the -o dax mount option.  DAX operations to
   the raw PMEM namespace part lack struct page and can fail in
   interesting/unexpected ways when doing things like fork(), examining
   memory with gdb, etc.

 * We can create a dm-stripe or dm-linear device which is made up of an
   fsdax PMEM namespace and a BRD ramdisk which can hold a filesystem
   mounted with the -o dax mount option.  All I/O to this filesystem
   will fail.

 * In DM you can't transition a dm target which could possibly support
   DAX (mode DM_TYPE_DAX_BIO_BASED) to one which can't support DAX
   (mode DM_TYPE_BIO_BASED), even if you never use DAX.

The first 2 patches in this series are prep work from Darrick and Dave
which improve bdev_dax_supported().  The last 5 problems fix the above
mentioned problems in DM.  I feel that this series simplifies the
handling of DAX devices in DM, and the last 5 DM-related patches have a
net code reduction of 50 lines.

Darrick J. Wong (1):
  fs: allow per-device dax status checking for filesystems

Dave Jiang (1):
  dax: change bdev_dax_supported() to support boolean returns

Ross Zwisler (5):
  dm: fix test for DAX device support
  dm: prevent DAX mounts if not supported
  dm: remove DM_TYPE_DAX_BIO_BASED dm_queue_mode
  dm-snap: remove unnecessary direct_access() stub
  dm-error: remove unnecessary direct_access() stub

 drivers/dax/super.c           | 44 +++++++++++++++++++++----------------------
 drivers/md/dm-ioctl.c         | 16 ++++++----------
 drivers/md/dm-snap.c          |  8 --------
 drivers/md/dm-table.c         | 29 +++++++++++-----------------
 drivers/md/dm-target.c        |  7 -------
 drivers/md/dm.c               |  7 ++-----
 fs/ext2/super.c               |  3 +--
 fs/ext4/super.c               |  3 +--
 fs/xfs/xfs_ioctl.c            |  3 ++-
 fs/xfs/xfs_iops.c             | 30 ++++++++++++++++++++++++-----
 fs/xfs/xfs_super.c            | 10 ++++++++--
 include/linux/dax.h           | 12 ++++--------
 include/linux/device-mapper.h |  8 ++++++--
 13 files changed, 88 insertions(+), 92 deletions(-)

-- 
2.14.3

             reply	other threads:[~2018-05-25 22:01 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-25 22:00 Ross Zwisler [this message]
2018-05-25 22:00 ` [PATCH resend 1/7] fs: allow per-device dax status checking for filesystems Ross Zwisler
2018-05-25 22:32   ` Eric Sandeen
2018-05-25 22:00 ` [PATCH resend 2/7] dax: change bdev_dax_supported() to support boolean returns Ross Zwisler
2018-05-25 22:00 ` [PATCH resend 3/7] dm: fix test for DAX device support Ross Zwisler
2018-05-25 22:00 ` [PATCH resend 4/7] dm: prevent DAX mounts if not supported Ross Zwisler
2018-05-25 22:00 ` [PATCH resend 5/7] dm: remove DM_TYPE_DAX_BIO_BASED dm_queue_mode Ross Zwisler
2018-05-25 22:00 ` [PATCH resend 6/7] dm-snap: remove unnecessary direct_access() stub Ross Zwisler
2018-05-25 22:00 ` [PATCH resend 7/7] dm-error: " Ross Zwisler

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