[3.16.y-ckt stable] Patch "drbd: compute the end before rb_insert_augmented()" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    drbd: compute the end before rb_insert_augmented()

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?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt2.

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

------

>From 84110b710b665a3fee14d27c5b719cc49a3dc69c Mon Sep 17 00:00:00 2001
From: Lai Jiangshan <laijs at cn.fujitsu.com>
Date: Thu, 18 Sep 2014 16:49:41 +0200
Subject: drbd: compute the end before rb_insert_augmented()

commit 82cfb90bc99d7b7e0ec62d0505b9d4f06805d5db upstream.

Commit 98683650 "Merge branch 'drbd-8.4_ed6' into
for-3.8-drivers-drbd-8.4_ed6" switches to the new augment API, but the
new API requires that the tree is augmented before rb_insert_augmented()
is called, which is missing.

So we add the augment-code to drbd_insert_interval() when it travels the
tree up to down before rb_insert_augmented().  See the example in
include/linux/interval_tree_generic.h or Documentation/rbtree.txt.

drbd_insert_interval() may cancel the insertion when traveling, in this
case, the just added augment-code does nothing before cancel since the
@this node is already in the subtrees in this case.

CC: Michel Lespinasse <walken at google.com>
Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
Signed-off-by: Andreas Gruenbacher <agruen at linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner at linbit.com>
Signed-off-by: Jens Axboe <axboe at fb.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/block/drbd/drbd_interval.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/block/drbd/drbd_interval.c b/drivers/block/drbd/drbd_interval.c
index 89c497c630b4..04a14e0f8878 100644
--- a/drivers/block/drbd/drbd_interval.c
+++ b/drivers/block/drbd/drbd_interval.c
@@ -79,6 +79,7 @@ bool
 drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
 {
 	struct rb_node **new = &root->rb_node, *parent = NULL;
+	sector_t this_end = this->sector + (this->size >> 9);

 	BUG_ON(!IS_ALIGNED(this->size, 512));

@@ -87,6 +88,8 @@ drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
 			rb_entry(*new, struct drbd_interval, rb);

 		parent = *new;
+		if (here->end < this_end)
+			here->end = this_end;
 		if (this->sector < here->sector)
 			new = &(*new)->rb_left;
 		else if (this->sector > here->sector)
@@ -99,6 +102,7 @@ drbd_insert_interval(struct rb_root *root, struct drbd_interval *this)
 			return false;
 	}

+	this->end = this_end;
 	rb_link_node(&this->rb, parent, new);
 	rb_insert_augmented(&this->rb, root, &augment_callbacks);
 	return true;
--
2.1.0