Re: [PATCH V7 4/8] block: deadline-iosched: Introduce dispatch helpers

[Martin K. Petersen]

Damien,

> 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().

Reviewed-by: Martin K. Petersen 

-- 
Martin K. Petersen  Oracle Linux Engineering

Re: [PATCH V7 4/8] block: deadline-iosched: Introduce dispatch helpers

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig 

[PATCH V7 4/8] block: deadline-iosched: Introduce dispatch helpers

[Damien Le Moal]

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 
---
 block/deadline-iosched.c | 47 +--
 1 file changed, 37 insertions(+), 10 deletions(-)

diff --git a/block/deadline-iosched.c b/block/deadline-iosched.c
index b83f77460d28..81e3f0897457 100644
--- 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)
 {
@@ -231,6 +229,35 @@ static inline int deadline_check_fifo(struct deadline_data 
*dd, int ddir)
 }
 
 /*
+ * 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(>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(>fifo_list[READ]);
const int writes = !list_empty(>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 @@ static int deadline_dispatch_requests(struct 
request_queue *q, int force)
/*
 * 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;
-- 
2.13.6