block: have ->poll_fn() return number of entries polled

We currently only really support sync poll, ie poll with 1 IO in flight.
This prepares us for supporting async poll.

Note that the returned value isn't necessarily 100% accurate. If poll
races with IRQ completion, we assume that the fact that the task is now
runnable means we found at least one entry. In reality it could be more
than 1, or not even 1. This is fine, the caller will just need to take
this into account.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7fc4abb4cc36e437a4ce684ef9eb1cf3824bf553..52b1c97cd7c6fba9d40c958dca8f96332c8b29c5 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -38,7 +38,7 @@
 #include "blk-mq-sched.h"
 #include "blk-rq-qos.h"
 
-static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
+static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie);
 static void blk_mq_poll_stats_start(struct request_queue *q);
 static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
 
@@ -3305,7 +3305,7 @@ static bool blk_mq_poll_hybrid_sleep(struct request_queue *q,
        return true;
 }
 
-static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
+static int __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
 {
        struct request_queue *q = hctx->queue;
        long state;
@@ -3318,7 +3318,7 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
         * straight to the busy poll loop.
         */
        if (blk_mq_poll_hybrid_sleep(q, hctx, rq))
-               return true;
+               return 1;
 
        hctx->poll_considered++;
 
@@ -3332,30 +3332,30 @@ static bool __blk_mq_poll(struct blk_mq_hw_ctx *hctx, struct request *rq)
                if (ret > 0) {
                        hctx->poll_success++;
                        __set_current_state(TASK_RUNNING);
-                       return true;
+                       return ret;
                }
 
                if (signal_pending_state(state, current))
                        __set_current_state(TASK_RUNNING);
 
                if (current->state == TASK_RUNNING)
-                       return true;
+                       return 1;
                if (ret < 0)
                        break;
                cpu_relax();
        }
 
        __set_current_state(TASK_RUNNING);
-       return false;
+       return 0;
 }
 
-static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
+static int blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
 {
        struct blk_mq_hw_ctx *hctx;
        struct request *rq;
 
        if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
-               return false;
+               return 0;
 
        hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
        if (!blk_qc_t_is_internal(cookie))
@@ -3369,7 +3369,7 @@ static bool blk_mq_poll(struct request_queue *q, blk_qc_t cookie)
                 * so we should be safe with just the NULL check.
                 */
                if (!rq)
-                       return false;
+                       return 0;
        }
 
        return __blk_mq_poll(hctx, rq);

diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 8b841f39734c7d235c2ce4c3092620ba1ca32d06..f9eeb3b5863290e1c94f09b91dbb58598176d286 100644 (file)
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -220,11 +220,11 @@ static blk_qc_t nvme_ns_head_make_request(struct request_queue *q,
        return ret;
 }
 
-static bool nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)
+static int nvme_ns_head_poll(struct request_queue *q, blk_qc_t qc)
 {
        struct nvme_ns_head *head = q->queuedata;
        struct nvme_ns *ns;
-       bool found = false;
+       int found = 0;
        int srcu_idx;
 
        srcu_idx = srcu_read_lock(&head->srcu);

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 1ad6eafc43f23fe553ba88e996316b7b80c1ad05..e97c0a3b2262d2aa5116903aed732aac1ae56d04 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -283,7 +283,7 @@ static inline unsigned short req_get_ioprio(struct request *req)
 struct blk_queue_ctx;
 
 typedef blk_qc_t (make_request_fn) (struct request_queue *q, struct bio *bio);
-typedef bool (poll_q_fn) (struct request_queue *q, blk_qc_t);
+typedef int (poll_q_fn) (struct request_queue *q, blk_qc_t);
 
 struct bio_vec;
 typedef int (dma_drain_needed_fn)(struct request *);