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[3.16.y-ckt,stable] Patch "dm btree remove: fix bug in redistribute3" has been added to staging queue

Message ID 1439297709-28918-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Aug. 11, 2015, 12:55 p.m. UTC
This is a note to let you know that I have just added a patch titled

    dm btree remove: fix bug in redistribute3

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt16.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From 8891356283cfc8c11548d7d1f658d664ebc699a1 Mon Sep 17 00:00:00 2001
From: Dennis Yang <shinrairis@gmail.com>
Date: Fri, 26 Jun 2015 15:25:48 +0100
Subject: dm btree remove: fix bug in redistribute3

commit 4c7e309340ff85072e96f529582d159002c36734 upstream.

redistribute3() shares entries out across 3 nodes.  Some entries were
being moved the wrong way, breaking the ordering.  This manifested as a
BUG() in dm-btree-remove.c:shift() when entries were removed from the
btree.

For additional context see:
https://www.redhat.com/archives/dm-devel/2015-May/msg00113.html

Signed-off-by: Dennis Yang <shinrairis@gmail.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/md/persistent-data/dm-btree-remove.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/drivers/md/persistent-data/dm-btree-remove.c b/drivers/md/persistent-data/dm-btree-remove.c
index b88757cd0d1d..a03178e91a79 100644
--- a/drivers/md/persistent-data/dm-btree-remove.c
+++ b/drivers/md/persistent-data/dm-btree-remove.c
@@ -309,8 +309,8 @@  static void redistribute3(struct dm_btree_info *info, struct btree_node *parent,

 		if (s < 0 && nr_center < -s) {
 			/* not enough in central node */
-			shift(left, center, nr_center);
-			s = nr_center - target;
+			shift(left, center, -nr_center);
+			s += nr_center;
 			shift(left, right, s);
 			nr_right += s;
 		} else
@@ -323,7 +323,7 @@  static void redistribute3(struct dm_btree_info *info, struct btree_node *parent,
 		if (s > 0 && nr_center < s) {
 			/* not enough in central node */
 			shift(center, right, nr_center);
-			s = target - nr_center;
+			s -= nr_center;
 			shift(left, right, s);
 			nr_left -= s;
 		} else