From 2355060197f0d4bad2fdc16ca667b6fc8574766a Mon Sep 17 00:00:00 2001
From: Vivek Goyal <vgoyal@redhat.com>
Date: Wed, 1 Dec 2010 19:34:46 +0100
Subject: [PATCH] --- yaml --- r: 223455 b: refs/heads/master c:
 d1ae8ffdfaa16b2ab2e9346e81cf0ab6eaaae347 h: refs/heads/master i:   223453:
 275f3f56cffd10916cac0c122f3c4587b99b06b9   223451:
 eb2282b6b28310955a29013af4f523ee9aee6199   223447:
 f56dcc35e260ef91e603b7cfc2f539141e1e31fb   223439:
 3b02b34a0735d068f16be50ee814354e9e6a9b35   223423:
 31c8376b6976d6e6af8d4aa01dfaf8fd86502976 v: v3

---
 [refs]                     |  2 +-
 trunk/block/blk-throttle.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 30a9ecaf0043..b563ea197335 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 5478755616ae2ef1ce144dded589b62b2a50d575
+refs/heads/master: d1ae8ffdfaa16b2ab2e9346e81cf0ab6eaaae347
diff --git a/trunk/block/blk-throttle.c b/trunk/block/blk-throttle.c
index 004be80fd894..2d134b7c40a3 100644
--- a/trunk/block/blk-throttle.c
+++ b/trunk/block/blk-throttle.c
@@ -355,6 +355,12 @@ throtl_start_new_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
 			tg->slice_end[rw], jiffies);
 }
 
+static inline void throtl_set_slice_end(struct throtl_data *td,
+		struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
+{
+	tg->slice_end[rw] = roundup(jiffy_end, throtl_slice);
+}
+
 static inline void throtl_extend_slice(struct throtl_data *td,
 		struct throtl_grp *tg, bool rw, unsigned long jiffy_end)
 {
@@ -391,6 +397,16 @@ throtl_trim_slice(struct throtl_data *td, struct throtl_grp *tg, bool rw)
 	if (throtl_slice_used(td, tg, rw))
 		return;
 
+	/*
+	 * A bio has been dispatched. Also adjust slice_end. It might happen
+	 * that initially cgroup limit was very low resulting in high
+	 * slice_end, but later limit was bumped up and bio was dispached
+	 * sooner, then we need to reduce slice_end. A high bogus slice_end
+	 * is bad because it does not allow new slice to start.
+	 */
+
+	throtl_set_slice_end(td, tg, rw, jiffies + throtl_slice);
+
 	time_elapsed = jiffies - tg->slice_start[rw];
 
 	nr_slices = time_elapsed / throtl_slice;