1 files changed, 43 insertions, 23 deletions

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 0d3b70de3d80..a55a9bd75bd1 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -154,6 +154,8 @@ struct cfq_queue {
 	unsigned long rb_key;
 	/* prio tree member */
 	struct rb_node p_node;
+	/* prio tree root we belong to, if any */
+	struct rb_root *p_root;
 	/* sorted list of pending requests */
 	struct rb_root sort_list;
 	/* if fifo isn't expired, next request to serve */
@@ -558,10 +560,10 @@ static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 }
 
 static struct cfq_queue *
-cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
-		     struct rb_node **ret_parent, struct rb_node ***rb_link)
+cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root,
+		     sector_t sector, struct rb_node **ret_parent,
+		     struct rb_node ***rb_link)
 {
-	struct rb_root *root = &cfqd->prio_trees[ioprio];
 	struct rb_node **p, *parent;
 	struct cfq_queue *cfqq = NULL;
 
@@ -584,34 +586,38 @@ cfq_prio_tree_lookup(struct cfq_data *cfqd, int ioprio, sector_t sector,
 		else
 			break;
 		p = n;
+		cfqq = NULL;
 	}
 
 	*ret_parent = parent;
 	if (rb_link)
 		*rb_link = p;
-	return NULL;
+	return cfqq;
 }
 
 static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-	struct rb_root *root = &cfqd->prio_trees[cfqq->ioprio];
 	struct rb_node **p, *parent;
 	struct cfq_queue *__cfqq;
 
-	if (!RB_EMPTY_NODE(&cfqq->p_node))
-		rb_erase_init(&cfqq->p_node, root);
+	if (cfqq->p_root) {
+		rb_erase(&cfqq->p_node, cfqq->p_root);
+		cfqq->p_root = NULL;
+	}
 
 	if (cfq_class_idle(cfqq))
 		return;
 	if (!cfqq->next_rq)
 		return;
 
-	__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->ioprio, cfqq->next_rq->sector,
+	cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio];
+	__cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, cfqq->next_rq->sector,
 					 &parent, &p);
-	BUG_ON(__cfqq);
-
-	rb_link_node(&cfqq->p_node, parent, p);
-	rb_insert_color(&cfqq->p_node, root);
+	if (!__cfqq) {
+		rb_link_node(&cfqq->p_node, parent, p);
+		rb_insert_color(&cfqq->p_node, cfqq->p_root);
+	} else
+		cfqq->p_root = NULL;
 }
 
 /*
@@ -656,8 +662,10 @@ static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 
 	if (!RB_EMPTY_NODE(&cfqq->rb_node))
 		cfq_rb_erase(&cfqq->rb_node, &cfqd->service_tree);
-	if (!RB_EMPTY_NODE(&cfqq->p_node))
-		rb_erase_init(&cfqq->p_node, &cfqd->prio_trees[cfqq->ioprio]);
+	if (cfqq->p_root) {
+		rb_erase(&cfqq->p_node, cfqq->p_root);
+		cfqq->p_root = NULL;
+	}
 
 	BUG_ON(!cfqd->busy_queues);
 	cfqd->busy_queues--;
@@ -947,20 +955,24 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
 		return cfqd->last_position - rq->sector;
 }
 
+#define CIC_SEEK_THR	8 * 1024
+#define CIC_SEEKY(cic)	((cic)->seek_mean > CIC_SEEK_THR)
+
 static inline int cfq_rq_close(struct cfq_data *cfqd, struct request *rq)
 {
 	struct cfq_io_context *cic = cfqd->active_cic;
+	sector_t sdist = cic->seek_mean;
 
 	if (!sample_valid(cic->seek_samples))
-		return 0;
+		sdist = CIC_SEEK_THR;
 
-	return cfq_dist_from_last(cfqd, rq) <= cic->seek_mean;
+	return cfq_dist_from_last(cfqd, rq) <= sdist;
 }
 
 static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
 				    struct cfq_queue *cur_cfqq)
 {
-	struct rb_root *root = &cfqd->prio_trees[cur_cfqq->ioprio];
+	struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio];
 	struct rb_node *parent, *node;
 	struct cfq_queue *__cfqq;
 	sector_t sector = cfqd->last_position;
@@ -972,8 +984,7 @@ static struct cfq_queue *cfqq_close(struct cfq_data *cfqd,
 	 * First, if we find a request starting at the end of the last
 	 * request, choose it.
 	 */
-	__cfqq = cfq_prio_tree_lookup(cfqd, cur_cfqq->ioprio,
-				      sector, &parent, NULL);
+	__cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL);
 	if (__cfqq)
 		return __cfqq;
 
@@ -1039,9 +1050,6 @@ static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd,
 	return cfqq;
 }
 
-
-#define CIC_SEEKY(cic) ((cic)->seek_mean > (8 * 1024))
-
 static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
 	struct cfq_queue *cfqq = cfqd->active_queue;
@@ -1908,7 +1916,9 @@ cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_io_context *cic,
 	sector_t sdist;
 	u64 total;
 
-	if (cic->last_request_pos < rq->sector)
+	if (!cic->last_request_pos)
+		sdist = 0;
+	else if (cic->last_request_pos < rq->sector)
 		sdist = rq->sector - cic->last_request_pos;
 	else
 		sdist = cic->last_request_pos - rq->sector;
@@ -2443,12 +2453,22 @@ static void cfq_exit_queue(struct elevator_queue *e)
 static void *cfq_init_queue(struct request_queue *q)
 {
 	struct cfq_data *cfqd;
+	int i;
 
 	cfqd = kmalloc_node(sizeof(*cfqd), GFP_KERNEL | __GFP_ZERO, q->node);
 	if (!cfqd)
 		return NULL;
 
 	cfqd->service_tree = CFQ_RB_ROOT;
+
+	/*
+	 * Not strictly needed (since RB_ROOT just clears the node and we
+	 * zeroed cfqd on alloc), but better be safe in case someone decides
+	 * to add magic to the rb code
+	 */
+	for (i = 0; i < CFQ_PRIO_LISTS; i++)
+		cfqd->prio_trees[i] = RB_ROOT;
+
 	INIT_LIST_HEAD(&cfqd->cic_list);
 
 	cfqd->queue = q;