[1/5] null_blk: create a helper for throttling

Commit Message

Chaitanya Kulkarni June 29, 2019, 5:04 a.m. UTC

This patch creates a helper for handling throttling code in the
null_handle_cmd().

Signed-off-by: Chaitanya Kulkarni <[e-mail]>
---
 drivers/block/null_blk_main.c | 43 +++++++++++++++++++++++------------
 1 file changed, 28 insertions(+), 15 deletions(-)

Comments

Christoph Hellwig July 1, 2019, 6:22 a.m. UTC | #1

> +	if (!test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags))
> +		goto out;

Maybe keep this check in the caller to make it more obvious
when it actually does something?

Patch

diff --git a/drivers/block/null_blk_main.c b/drivers/block/null_blk_main.c
index 99328ded60d1..98e2985f57fc 100644
--- a/drivers/block/null_blk_main.c
+++ b/drivers/block/null_blk_main.c
@@ -1133,28 +1133,41 @@  static void null_restart_queue_async(struct nullb *nullb)
 		blk_mq_start_stopped_hw_queues(q, true);
 }
 
-static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
+static inline blk_status_t null_handle_throttled(struct nullb_cmd *cmd)
 {
 	struct nullb_device *dev = cmd->nq->dev;
 	struct nullb *nullb = dev->nullb;
-	int err = 0;
+	blk_status_t sts = BLK_STS_OK;
+	struct request *rq = cmd->rq;
 
-	if (test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags)) {
-		struct request *rq = cmd->rq;
+	if (!test_bit(NULLB_DEV_FL_THROTTLED, &dev->flags))
+		goto out;
 
-		if (!hrtimer_active(&nullb->bw_timer))
-			hrtimer_restart(&nullb->bw_timer);
+	if (!hrtimer_active(&nullb->bw_timer))
+		hrtimer_restart(&nullb->bw_timer);
 
-		if (atomic_long_sub_return(blk_rq_bytes(rq),
-				&nullb->cur_bytes) < 0) {
-			null_stop_queue(nullb);
-			/* race with timer */
-			if (atomic_long_read(&nullb->cur_bytes) > 0)
-				null_restart_queue_async(nullb);
-			/* requeue request */
-			return BLK_STS_DEV_RESOURCE;
-		}
+	if (atomic_long_sub_return(blk_rq_bytes(rq), &nullb->cur_bytes) < 0) {
+		null_stop_queue(nullb);
+		/* race with timer */
+		if (atomic_long_read(&nullb->cur_bytes) > 0)
+			null_restart_queue_async(nullb);
+		/* requeue request */
+		sts = BLK_STS_DEV_RESOURCE;
 	}
+out:
+	return sts;
+}
+
+static blk_status_t null_handle_cmd(struct nullb_cmd *cmd)
+{
+	struct nullb_device *dev = cmd->nq->dev;
+	struct nullb *nullb = dev->nullb;
+	blk_status_t sts;
+	int err = 0;
+
+	sts = null_handle_throttled(cmd);
+	if (sts != BLK_STS_OK)
+		return sts;
 
 	if (nullb->dev->badblocks.shift != -1) {
 		int bad_sectors;