1 files changed, 26 insertions, 27 deletions

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 1a511ffaf8a4..a054eef8dff6 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.