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From: Christoph Hellwig <hch@lst.de>
To: Jens Axboe <axboe@kernel.dk>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>,
	Ming Lei <ming.lei@redhat.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Keith Busch <kbusch@kernel.org>, Sagi Grimberg <sagi@grimberg.me>,
	"Wunderlich, Mark" <mark.wunderlich@intel.com>,
	"Vasudevan, Anil" <anil.vasudevan@intel.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-nvme@lists.infradead.org
Subject: [PATCH 08/16] block: replace the spin argument to blk_iopoll with a flags argument
Date: Tue, 15 Jun 2021 15:10:26 +0200	[thread overview]
Message-ID: <20210615131034.752623-9-hch@lst.de> (raw)
In-Reply-To: <20210615131034.752623-1-hch@lst.de>

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>
---
 block/blk-mq.c           | 17 +++++++----------
 drivers/nvme/host/core.c |  2 +-
 fs/block_dev.c           |  8 ++++----
 fs/io_uring.c            | 14 +++++++-------
 fs/iomap/direct-io.c     |  6 +++---
 include/linux/blkdev.h   |  4 +++-
 include/linux/fs.h       |  2 +-
 include/linux/iomap.h    |  2 +-
 mm/page_io.c             |  2 +-
 9 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index cb94cf9bcf99..c2b2c7abd712 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3951,7 +3951,7 @@ 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 = current->state;
@@ -3974,7 +3974,7 @@ static int blk_mq_poll_classic(struct request_queue *q, blk_qc_t cookie,
 		if (current->state == TASK_RUNNING)
 			return 1;
 
-		if (ret < 0 || !spin)
+		if (ret < 0 || (flags & BLK_POLL_ONESHOT))
 			break;
 		cpu_relax();
 	} while (!need_resched());
@@ -3987,15 +3987,13 @@ 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))
@@ -4004,12 +4002,11 @@ 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/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 24bcae88587a..115c8d90530a 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1032,7 +1032,7 @@ static void nvme_execute_rq_polled(struct request_queue *q,
 	blk_execute_rq_nowait(bd_disk, rq, at_head, nvme_end_sync_rq);
 
 	while (!completion_done(&wait)) {
-		blk_poll(q, request_to_qc_t(rq->mq_hctx, rq), true);
+		blk_poll(q, request_to_qc_t(rq->mq_hctx, rq), 0);
 		cond_resched();
 	}
 }
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 8600c651b0b0..c9bdaa138909 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -286,7 +286,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
 		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);
@@ -319,12 +319,12 @@ 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)
@@ -475,7 +475,7 @@ 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);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5f82954004f6..de8d39e9a154 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2290,18 +2290,18 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 			long min)
 {
+	unsigned int poll_flags = 0;
 	struct io_kiocb *req, *tmp;
 	LIST_HEAD(done);
-	bool spin;
-	int ret;
+	int ret = 0;
 
 	/*
 	 * Only spin for completions if we don't have multiple devices hanging
 	 * off our complete list, and we're under the requested amount.
 	 */
-	spin = !ctx->poll_multi_file && *nr_events < min;
+	if (ctx->poll_multi_file || *nr_events >= min)
+		poll_flags |= BLK_POLL_ONESHOT;
 
-	ret = 0;
 	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {
 		struct kiocb *kiocb = &req->rw.kiocb;
 
@@ -2317,7 +2317,7 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		if (!list_empty(&done))
 			break;
 
-		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
+		ret = kiocb->ki_filp->f_op->iopoll(kiocb, poll_flags);
 		if (ret < 0)
 			break;
 
@@ -2325,8 +2325,8 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		if (READ_ONCE(req->iopoll_completed))
 			list_move_tail(&req->inflight_entry, &done);
 
-		if (ret && spin)
-			spin = false;
+		if (ret)
+			poll_flags |= BLK_POLL_ONESHOT;
 		ret = 0;
 	}
 
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index d5637f467109..9b6c26da3a2d 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -49,13 +49,13 @@ struct iomap_dio {
 	};
 };
 
-int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
+int iomap_dio_iopoll(struct kiocb *kiocb, unsigned int flags)
 {
 	struct request_queue *q = READ_ONCE(kiocb->private);
 
 	if (!q)
 		return 0;
-	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin);
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), flags);
 }
 EXPORT_SYMBOL_GPL(iomap_dio_iopoll);
 
@@ -640,7 +640,7 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 			if (!(iocb->ki_flags & IOCB_HIPRI) ||
 			    !dio->submit.last_queue ||
 			    !blk_poll(dio->submit.last_queue,
-					 dio->submit.cookie, true))
+					 dio->submit.cookie, 0))
 				blk_io_schedule();
 		}
 		__set_current_state(TASK_RUNNING);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index d66d0da72529..c7061f25ee5f 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -946,7 +946,9 @@ extern const char *blk_op_str(unsigned int op);
 int blk_status_to_errno(blk_status_t status);
 blk_status_t errno_to_blk_status(int errno);
 
-int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin);
+/* only poll the hardware once, don't continue until a completion was found */
+#define BLK_POLL_ONESHOT		(1 << 0)
+int blk_poll(struct request_queue *q, blk_qc_t cookie, unsigned int flags);
 
 static inline struct request_queue *bdev_get_queue(struct block_device *bdev)
 {
diff --git a/include/linux/fs.h b/include/linux/fs.h
index c3c88fdb9b2a..483fb557d92f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2026,7 +2026,7 @@ struct file_operations {
 	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
 	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
 	ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
-	int (*iopoll)(struct kiocb *kiocb, bool spin);
+	int (*iopoll)(struct kiocb *kiocb, unsigned int flags);
 	int (*iterate) (struct file *, struct dir_context *);
 	int (*iterate_shared) (struct file *, struct dir_context *);
 	__poll_t (*poll) (struct file *, struct poll_table_struct *);
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index c87d0cb0de6d..56e5949ccb60 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -275,7 +275,7 @@ struct iomap_dio *__iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
 		unsigned int dio_flags);
 ssize_t iomap_dio_complete(struct iomap_dio *dio);
-int iomap_dio_iopoll(struct kiocb *kiocb, bool spin);
+int iomap_dio_iopoll(struct kiocb *kiocb, unsigned int flags);
 
 #ifdef CONFIG_SWAP
 struct file;
diff --git a/mm/page_io.c b/mm/page_io.c
index c493ce9ebcf5..5d5543fcefa4 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -428,7 +428,7 @@ int swap_readpage(struct page *page, bool synchronous)
 		if (!READ_ONCE(bio->bi_private))
 			break;
 
-		if (!blk_poll(disk->queue, qc, true))
+		if (!blk_poll(disk->queue, qc, 0))
 			blk_io_schedule();
 	}
 	__set_current_state(TASK_RUNNING);
-- 
2.30.2


  parent reply	other threads:[~2021-06-15 13:13 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-15 13:10 switch block layer polling to a bio based model v4 Christoph Hellwig
2021-06-15 13:10 ` [PATCH 01/16] direct-io: remove blk_poll support Christoph Hellwig
2021-06-15 13:10 ` [PATCH 02/16] block: don't try to poll multi-bio I/Os in __blkdev_direct_IO Christoph Hellwig
2021-06-15 13:10 ` [PATCH 03/16] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw Christoph Hellwig
2021-06-15 13:10 ` [PATCH 04/16] blk-mq: factor out a blk_qc_to_hctx helper Christoph Hellwig
2021-06-15 13:10 ` [PATCH 05/16] blk-mq: factor out a "classic" poll helper Christoph Hellwig
2021-06-15 13:10 ` [PATCH 06/16] blk-mq: remove blk_qc_t_to_tag and blk_qc_t_is_internal Christoph Hellwig
2021-06-15 13:10 ` [PATCH 07/16] blk-mq: remove blk_qc_t_valid Christoph Hellwig
2021-06-15 13:10 ` Christoph Hellwig [this message]
2021-06-15 13:10 ` [PATCH 09/16] io_uring: don't sleep when polling for I/O Christoph Hellwig
2021-06-15 13:10 ` [PATCH 10/16] block: rename REQ_HIPRI to REQ_POLLED Christoph Hellwig
2021-06-15 13:10 ` [PATCH 11/16] block: use SLAB_TYPESAFE_BY_RCU for the bio slab Christoph Hellwig
2021-06-15 13:10 ` [PATCH 12/16] block: define 'struct bvec_iter' as packed Christoph Hellwig
2021-06-15 13:10 ` [PATCH 13/16] block: switch polling to be bio based Christoph Hellwig
2021-06-16  2:30   ` Ming Lei
2021-06-18 14:01     ` Christoph Hellwig
2021-06-18 14:27       ` Ming Lei
2021-06-21  7:20         ` Christoph Hellwig
2021-06-21  8:35           ` Ming Lei
2021-06-15 13:10 ` [PATCH 14/16] block: don't allow writing to the poll queue attribute Christoph Hellwig
2021-06-15 13:10 ` [PATCH 15/16] nvme-multipath: set QUEUE_FLAG_NOWAIT Christoph Hellwig
2021-06-15 13:10 ` [PATCH 16/16] nvme-multipath: enable polled I/O Christoph Hellwig
2021-06-15 14:37 ` switch block layer polling to a bio based model v4 Keith Busch
2021-06-15 16:06   ` Christoph Hellwig

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