->poll_fn was introduced in commit ea435e1b9392 ("block: add a poll_fn
callback to struct request_queue") to support bio-based queues such as
nvme multipath, but was later removed in commit 529262d56dbe ("block:
remove ->poll_fn").
Given commit c62b37d96b6e ("block: move ->make_request_fn to struct
block_device_operations") restore the possibility of bio-based IO
polling support by adding an ->poll method to gendisk->fops.
Make blk_mq_poll() specific to blk-mq, while blk_bio_poll() is
originally a copy from blk_mq_poll(), and is specific to bio-based
polling. Currently hybrid polling is not supported by bio-based polling.
Signed-off-by: Jeffle Xu <jefflexu@xxxxxxxxxxxxxxxxx>
---
block/blk-core.c | 58 ++++++++++++++++++++++++++++++++++++++++++
block/blk-mq.c | 22 +---------------
include/linux/blk-mq.h | 1 +
include/linux/blkdev.h | 1 +
4 files changed, 61 insertions(+), 21 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index fc60ff208497..6d7d53030d7c 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1119,6 +1119,64 @@ blk_qc_t submit_bio(struct bio *bio)
}
EXPORT_SYMBOL(submit_bio);
+
+static int blk_bio_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
+{
+ long state;
+ struct gendisk *disk = queue_to_disk(q);
+
+ state = current->state;
+ do {
+ int ret;
+
+ ret = disk->fops->poll(q, cookie);
+ if (ret > 0) {
+ __set_current_state(TASK_RUNNING);
+ return ret;
+ }
+
+ if (signal_pending_state(state, current))
+ __set_current_state(TASK_RUNNING);
+
+ if (current->state == TASK_RUNNING)
+ return 1;
+ if (ret < 0 || !spin)
+ break;
+ cpu_relax();
+ } while (!need_resched());
+
+ __set_current_state(TASK_RUNNING);
+ return 0;
+}
+
+/**
+ * blk_poll - poll for IO completions
+ * @q: the queue
+ * @cookie: cookie passed back at IO submission time
+ * @spin: whether to spin for completions
+ *
+ * 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).
+ */
+int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
+{
+ if (!blk_qc_t_valid(cookie) ||
+ !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
+ return 0;
+
+ if (current->plug)
+ blk_flush_plug_list(current->plug, false);
+
+ if (queue_is_mq(q))
+ return blk_mq_poll(q, cookie, spin);
+ else
+ return blk_bio_poll(q, cookie, spin);
+}
+EXPORT_SYMBOL_GPL(blk_poll);
+
/**
* blk_cloned_rq_check_limits - Helper function to check a cloned request
* for the new queue limits
diff --git a/block/blk-mq.c b/block/blk-mq.c
index d4d7c1caa439..214fa30b460a 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3852,30 +3852,11 @@ static bool blk_mq_poll_hybrid(struct request_queue *q,
return blk_mq_poll_hybrid_sleep(q, rq);
}
-/**
- * blk_poll - poll for IO completions
- * @q: the queue
- * @cookie: cookie passed back at IO submission time
- * @spin: whether to spin for completions
- *
- * 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).
- */
-int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
+int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
{
struct blk_mq_hw_ctx *hctx;
long state;
- if (!blk_qc_t_valid(cookie) ||
- !test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
- return 0;
-
- if (current->plug)
- blk_flush_plug_list(current->plug, false);
-
hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)];
/*
@@ -3917,7 +3898,6 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin)
__set_current_state(TASK_RUNNING);
return 0;
}
-EXPORT_SYMBOL_GPL(blk_poll);
unsigned int blk_mq_rq_cpu(struct request *rq)
{
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 2c473c9b8990..6a7b693b9917 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -615,6 +615,7 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio,
}
blk_qc_t blk_mq_submit_bio(struct bio *bio);
+int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin);
void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx,
struct lock_class_key *key);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index b81a9fe015ab..9dc83c30e7bc 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1866,6 +1866,7 @@ static inline void blk_ksm_unregister(struct request_queue *q) { }
struct block_device_operations {
blk_qc_t (*submit_bio) (struct bio *bio);
+ int (*poll)(struct request_queue *q, blk_qc_t cookie);
int (*open) (struct block_device *, fmode_t);
void (*release) (struct gendisk *, fmode_t);
int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int);
--
2.27.0
