block: replace the spin argument to blk_iopoll with a flags argument

Switch the boolean spin argument to blk_poll to passing a set of flags
instead.  This will allow to control polling behavior in a more fine
grained way.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@intel.com>
Link: https://lore.kernel.org/r/20211012111226.760968-10-hch@lst.de
[axboe: adapt to changed io_uring iopoll]
Signed-off-by: Jens Axboe <axboe@kernel.dk>

3 files changed, 12 insertions, 15 deletions

diff --git a/block/blk-exec.c b/block/blk-exec.c
index d6cd501c0d34..1fa7f25e5726 100644
--- a/block/blk-exec.c
+++ b/block/blk-exec.c
@@ -71,7 +71,7 @@ static bool blk_rq_is_poll(struct request *rq)
 static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
 {
 	do {
-		blk_poll(rq->q, request_to_qc_t(rq->mq_hctx, rq), true);
+		blk_poll(rq->q, request_to_qc_t(rq->mq_hctx, rq), 0);
 		cond_resched();
 	} while (!completion_done(wait));
 }
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7d0d947921a6..6609e10657a8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4052,7 +4052,7 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, blk_qc_t qc)
 }
 
 static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
-		bool spin)
+		unsigned int flags)
 {
 	struct blk_mq_hw_ctx *hctx = blk_qc_to_hctx(q, cookie);
 	long state = get_current_state();
@@ -4075,7 +4075,7 @@ static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
 		if (task_is_running(current))
 			return 1;
 
-		if (ret < 0 || !spin)
+		if (ret < 0 || (flags & BLK_POLL_ONESHOT))
 			break;
 		cpu_relax();
 	} while (!need_resched());
@@ -4088,15 +4088,13 @@ static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
  * blk_poll - poll for IO completions
  * @q:  the queue
  * @cookie: cookie passed back at IO submission time
- * @spin: whether to spin for completions
+ * @flags: BLK_POLL_* flags that control the behavior
  *
  * Description:
  *    Poll for completions on the passed in queue. Returns number of
- *    completed entries found. If @spin is true, then blk_poll will continue
- *    looping until at least one completion is found, unless the task is
- *    otherwise marked running (or we need to reschedule).
+ *    completed entries found.
  */
-int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
+int blk_poll(struct request_queue *q, blk_qc_t cookie, unsigned int flags)
 {
 	if (cookie == BLK_QC_T_NONE ||
 	    !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
@@ -4105,12 +4103,11 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
 	if (current->plug)
 		blk_flush_plug_list(current->plug, false);
 
-	/* If specified not to spin, we also should not sleep. */
-	if (spin && q->poll_nsec != BLK_MQ_POLL_CLASSIC) {
+	if (q->poll_nsec != BLK_MQ_POLL_CLASSIC) {
 		if (blk_mq_poll_hybrid(q, cookie))
 			return 1;
 	}
-	return blk_mq_poll_classic(q, cookie, spin);
+	return blk_mq_poll_classic(q, cookie, flags);
 }
 EXPORT_SYMBOL_GPL(blk_poll);
 
diff --git a/block/fops.c b/block/fops.c
index 15324f2e5a91..db8f2fe68dd2 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -108,7 +108,7 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
 		if (!READ_ONCE(bio.bi_private))
 			break;
 		if (!(iocb->ki_flags & IOCB_HIPRI) ||
-		    !blk_poll(bdev_get_queue(bdev), qc, true))
+		    !blk_poll(bdev_get_queue(bdev), qc, 0))
 			blk_io_schedule();
 	}
 	__set_current_state(TASK_RUNNING);
@@ -141,12 +141,12 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
-static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+static int blkdev_iopoll(struct kiocb *kiocb, unsigned int flags)
 {
 	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
 	struct request_queue *q = bdev_get_queue(bdev);
 
-	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), flags);
 }
 
 static void blkdev_bio_end_io(struct bio *bio)
@@ -297,7 +297,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
 		if (!READ_ONCE(dio->waiter))
 			break;
 
-		if (!do_poll || !blk_poll(bdev_get_queue(bdev), qc, true))
+		if (!do_poll || !blk_poll(bdev_get_queue(bdev), qc, 0))
 			blk_io_schedule();
 	}
 	__set_current_state(TASK_RUNNING);