After the recent updates to use generation number and state based
synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except
to avoid firing the same timeout multiple times.
Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag
RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple
times. This removes atomic bitops from hot paths too.
v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out().
v3: Added RQF_MQ_TIMEOUT_EXPIRED flag.
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: "jianchao.wang" <jianchao.w.wang@xxxxxxxxxx>
---
block/blk-mq.c | 15 +++++++--------
block/blk-timeout.c | 1 +
include/linux/blkdev.h | 2 ++
3 files changed, 10 insertions(+), 8 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index bed4cb8..050d982 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -628,8 +628,7 @@ void blk_mq_complete_request(struct request *rq)
* hctx_lock() covers both issue and completion paths.
*/
hctx_lock(hctx, &srcu_idx);
- if (blk_mq_rq_aborted_gstate(rq) != rq->gstate &&
- !blk_mark_rq_complete(rq))
+ if (blk_mq_rq_aborted_gstate(rq) != rq->gstate)
__blk_mq_complete_request(rq);
hctx_unlock(hctx, srcu_idx);
}
@@ -679,8 +678,6 @@ void blk_mq_start_request(struct request *rq)
preempt_enable();
set_bit(REQ_ATOM_STARTED, &rq->atomic_flags);
- if (test_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags))
- clear_bit(REQ_ATOM_COMPLETE, &rq->atomic_flags);
if (q->dma_drain_size && blk_rq_bytes(rq)) {
/*
@@ -831,6 +828,8 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved)
if (!test_bit(REQ_ATOM_STARTED, &req->atomic_flags))
return;
+ req->rq_flags |= RQF_MQ_TIMEOUT_EXPIRED;
+
if (ops->timeout)
ret = ops->timeout(req, reserved);
@@ -846,7 +845,6 @@ static void blk_mq_rq_timed_out(struct request *req, bool reserved)
*/
blk_mq_rq_update_aborted_gstate(req, 0);
blk_add_timer(req);
- blk_clear_rq_complete(req);
break;
case BLK_EH_NOT_HANDLED:
break;
@@ -865,7 +863,8 @@ static void blk_mq_check_expired(struct blk_mq_hw_ctx *hctx,
might_sleep();
- if (!test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
+ if ((rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) ||
+ !test_bit(REQ_ATOM_STARTED, &rq->atomic_flags))
return;
/* read coherent snapshots of @rq->state_gen and @rq->deadline */
@@ -900,8 +899,8 @@ static void blk_mq_terminate_expired(struct blk_mq_hw_ctx *hctx,
* now guaranteed to see @rq->aborted_gstate and yield. If
* @rq->aborted_gstate still matches @rq->gstate, @rq is ours.
*/
- if (READ_ONCE(rq->gstate) == rq->aborted_gstate &&
- !blk_mark_rq_complete(rq))
+ if (!(rq->rq_flags & RQF_MQ_TIMEOUT_EXPIRED) &&
+ READ_ONCE(rq->gstate) == rq->aborted_gstate)
blk_mq_rq_timed_out(rq, reserved);
}
diff --git a/block/blk-timeout.c b/block/blk-timeout.c
index d580af3..25c4ffa 100644
--- a/block/blk-timeout.c
+++ b/block/blk-timeout.c
@@ -209,6 +209,7 @@ void blk_add_timer(struct request *req)
req->timeout = q->rq_timeout;
req->deadline = jiffies + req->timeout;
+ req->rq_flags &= ~RQF_MQ_TIMEOUT_EXPIRED;
/*
* Only the non-mq case needs to add the request to a protected list.
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 2206607..e2a4afc 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -125,6 +125,8 @@ typedef __u32 __bitwise req_flags_t;
#define RQF_SPECIAL_PAYLOAD ((__force req_flags_t)(1 << 18))
/* The per-zone write lock is held for this request */
#define RQF_ZONE_WRITE_LOCKED ((__force req_flags_t)(1 << 19))
+/* timeout is expired */
+#define RQF_MQ_TIMEOUT_EXPIRED ((__force req_flags_t)(1 << 20))
/* flags that prevent us from merging requests: */
#define RQF_NOMERGE_FLAGS \
--
2.9.5
