Deadline iosched: Reset batch for ordered requests

[mirror_ubuntu-artful-kernel.git] / block / deadline-iosched.c

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index 1a511ffaf8a4edb49425fb88bba610fcfb45fdf4..cb94c838087a75f544df130bb51873270b55fa25 100644 (file)
--- 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;
 
        /*
@@ -300,12 +306,11 @@ dispatch_writes:
 dispatch_find_request:
        /*
         * we are not running a batch, find best request for selected data_dir
+        * and start a new batch
         */
        if (deadline_check_fifo(dd, data_dir)) {
                /* An expired request exists - satisfy it */
-               dd->batching = 0;
                rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
-               
        } else if (dd->next_rq[data_dir]) {
                /*
                 * The last req was the same dir and we have a next request in
@@ -319,12 +324,13 @@ dispatch_find_request:
                 * 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.