On 5/12/21 6:15 AM, Christoph Hellwig wrote:
There is no point in sleeping for the expected I/O completion timeout
in the io_uring async polling model as we never poll for a specific
I/O. Split the boolean spin argument to blk_poll into a set of flags
to control sleeping and the oneshot behavior separately.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
block/blk-mq.c | 18 ++++++++----------
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 | 6 +++++-
include/linux/fs.h | 2 +-
include/linux/iomap.h | 2 +-
mm/page_io.c | 2 +-
9 files changed, 31 insertions(+), 29 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ac0b517c5503..164e39d34bf6 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3873,7 +3873,7 @@ 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;
@@ -3896,7 +3896,7 @@ 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());
@@ -3909,15 +3909,13 @@ 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))
@@ -3926,12 +3924,12 @@ 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 (!(flags & BLK_POLL_NOSLEEP) &&
+ 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);
I think that the combination of oneshot and nosleep flags to replace
a boolen spin is a little hard to follow (especially that spin doesn't
mean spinning without sleeping).
Maybe we should break it to:
1. replace spin to flags with ONESHOT passed from io_uring (direct
replacement)
2. add NOSLEEP passed from io_uring as there is no need for it.
Just a suggestion though that would help (me at least) to follow
this more easily.
