deadline-iosched: Introduce dispatch helpers

Avoid directly referencing the next_rq and fifo_list arrays using the
helper functions deadline_next_request() and deadline_fifo_request() to
facilitate changes in the dispatch request selection in
deadline_dispatch_requests() for zoned block devices.

While at it, also remove the unnecessary forward declaration of the
function deadline_move_request().

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index b83f77460d28ffc77908a853dfb8ddd90e77ac81..81e3f0897457570d91c3ecc82d03e1d5c3a2b807 100644 (file)
--- a/block/deadline-iosched.c
+++ b/block/deadline-iosched.c
@@ -50,8 +50,6 @@ struct deadline_data {
        int front_merges;
 };
 
-static void deadline_move_request(struct deadline_data *, struct request *);
-
 static inline struct rb_root *
 deadline_rb_root(struct deadline_data *dd, struct request *rq)
 {
@@ -230,6 +228,35 @@ static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
        return 0;
 }
 
+/*
+ * For the specified data direction, return the next request to dispatch using
+ * arrival ordered lists.
+ */
+static struct request *
+deadline_fifo_request(struct deadline_data *dd, int data_dir)
+{
+       if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
+               return NULL;
+
+       if (list_empty(&dd->fifo_list[data_dir]))
+               return NULL;
+
+       return rq_entry_fifo(dd->fifo_list[data_dir].next);
+}
+
+/*
+ * For the specified data direction, return the next request to dispatch using
+ * sector position sorted lists.
+ */
+static struct request *
+deadline_next_request(struct deadline_data *dd, int data_dir)
+{
+       if (WARN_ON_ONCE(data_dir != READ && data_dir != WRITE))
+               return NULL;
+
+       return dd->next_rq[data_dir];
+}
+
 /*
  * deadline_dispatch_requests selects the best request according to
  * read/write expire, fifo_batch, etc
@@ -239,16 +266,15 @@ static int deadline_dispatch_requests(struct request_queue *q, int force)
        struct deadline_data *dd = q->elevator->elevator_data;
        const int reads = !list_empty(&dd->fifo_list[READ]);
        const int writes = !list_empty(&dd->fifo_list[WRITE]);
-       struct request *rq;
+       struct request *rq, *next_rq;
        int data_dir;
 
        /*
         * batches are currently reads XOR writes
         */
-       if (dd->next_rq[WRITE])
-               rq = dd->next_rq[WRITE];
-       else
-               rq = dd->next_rq[READ];
+       rq = deadline_next_request(dd, WRITE);
+       if (!rq)
+               rq = deadline_next_request(dd, READ);
 
        if (rq && dd->batching < dd->fifo_batch)
                /* we have a next request are still entitled to batch */
@@ -291,19 +317,20 @@ dispatch_find_request:
        /*
         * we are not running a batch, find best request for selected data_dir
         */
-       if (deadline_check_fifo(dd, data_dir) || !dd->next_rq[data_dir]) {
+       next_rq = deadline_next_request(dd, data_dir);
+       if (deadline_check_fifo(dd, data_dir) || !next_rq) {
                /*
                 * 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);
+               rq = deadline_fifo_request(dd, 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];
+               rq = next_rq;
        }
 
        dd->batching = 0;