Patch "blockdev: don't set S_DAX for misaligned partitions" has been added to the 4.1-stable tree

Patch "blockdev: don't set S_DAX for misaligned partitions" has been added to the 4.1-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    blockdev: don't set S_DAX for misaligned partitions

to the 4.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     blockdev-don-t-set-s_dax-for-misaligned-partitions.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From f0b2e563bc419df7c1b3d2f494574c25125f6aed Mon Sep 17 00:00:00 2001
From: Jeff Moyer <jmoyer@redhat.com>
Date: Fri, 14 Aug 2015 16:15:32 -0400
Subject: blockdev: don't set S_DAX for misaligned partitions

From: Jeff Moyer <jmoyer@redhat.com>

commit f0b2e563bc419df7c1b3d2f494574c25125f6aed upstream.

The dax code doesn't currently support misaligned partitions,
so disable O_DIRECT via dax until such time as that support
materializes.

Suggested-by: Boaz Harrosh <boaz@plexistor.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/block_dev.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1234,6 +1234,13 @@ static int __blkdev_get(struct block_dev
 				goto out_clear;
 			}
 			bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
+			/*
+			 * If the partition is not aligned on a page
+			 * boundary, we can't do dax I/O to it.
+			 */
+			if ((bdev->bd_part->start_sect % (PAGE_SIZE / 512)) ||
+			    (bdev->bd_part->nr_sects % (PAGE_SIZE / 512)))
+				bdev->bd_inode->i_flags &= ~S_DAX;
 		}
 	} else {
 		if (bdev->bd_contains == bdev) {


Patches currently in stable-queue which might be from jmoyer@redhat.com are

queue-4.1/blockdev-don-t-set-s_dax-for-misaligned-partitions.patch