2.6.24

 block

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 1a511ff..342448c 100644
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -55,6 +55,20 @@ static void deadline_move_request(struct deadline_data *, struct request *);
 
 #define RQ_RB_ROOT(dd, rq)   (&(dd)->sort_list[rq_data_dir((rq))])
 
+/*
+ * get the request after `rq' in sector-sorted order
+ */
+static inline struct request *
+deadline_latter_request(struct request *rq)
+{
+   struct rb_node *node = rb_next(&rq->rb_node);
+
+   if (node)
+      return rb_entry_rq(node);
+
+   return NULL;
+}
+
 static void
 deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
 {
@@ -74,13 +88,8 @@ deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
 {
    const int data_dir = rq_data_dir(rq);
 
-   if (dd->next_rq[data_dir] == rq) {
-      struct rb_node *rbnext = rb_next(&rq->rb_node);
-
-      dd->next_rq[data_dir] = NULL;
-      if (rbnext)
-         dd->next_rq[data_dir] = rb_entry_rq(rbnext);
-   }
+   if (dd->next_rq[data_dir] == rq)
+      dd->next_rq[data_dir] = deadline_latter_request(rq);
 
    elv_rb_del(RQ_RB_ROOT(dd, rq), rq);
 }
@@ -198,14 +207,11 @@ static void
 deadline_move_request(struct deadline_data *dd, struct request *rq)
 {
    const int data_dir = rq_data_dir(rq);
-   struct rb_node *rbnext = rb_next(&rq->rb_node);
 
    dd->next_rq[READ] = NULL;
    dd->next_rq[WRITE] = NULL;
+   dd->next_rq[data_dir] = deadline_latter_request(rq);
 
-   if (rbnext)
-      dd->next_rq[data_dir] = rb_entry_rq(rbnext);
-   
    dd->last_sector = rq->sector + rq->nr_sectors;
 
    /*
@@ -301,30 +307,23 @@ dispatch_find_request:
    /*
     * we are not running a batch, find best request for selected data_dir
     */
-   if (deadline_check_fifo(dd, data_dir)) {
-      /* An expired request exists - satisfy it */
-      dd->batching = 0;
+   if (deadline_check_fifo(dd, data_dir) || !dd->next_rq[data_dir]) {
+      /*
+       * A deadline has expired, the last request was in the other
+       * direction, or we have run out of higher-sectored requests.
+       * Start again from the request with the earliest expiry time.
+       */
       rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
-      
-   } else if (dd->next_rq[data_dir]) {
+   } else {
       /*
        * The last req was the same dir and we have a next request in
        * sort order. No expired requests so continue on from here.
        */
       rq = dd->next_rq[data_dir];
-   } else {
-      struct rb_node *node;
-      /*
-       * The last req was the other direction or we have run out of
-       * higher-sectored requests. Go back to the lowest sectored
-       * request (1 way elevator) and start a new batch.
-       */
-      dd->batching = 0;
-      node = rb_first(&dd->sort_list[data_dir]);
-      if (node)
-         rq = rb_entry_rq(node);
    }
 
+   dd->batching = 0;
+
 dispatch_request:
    /*
     * rq is the selected appropriate request.
@@ -468,7 +467,9 @@ static struct elevator_type iosched_deadline = {
 
 static int __init deadline_init(void)
 {
-   return elv_register(&iosched_deadline);
+   elv_register(&iosched_deadline);
+
+   return 0;
 }
 
 static void __exit deadline_exit(void)