Messages in this thread Patch in this message | | | From | Tejun Heo <> | Subject | [PATCH 5/7] blk-mq: remove REQ_ATOM_COMPLETE usages from blk-mq | Date | Sat, 16 Dec 2017 04:07:24 -0800 |
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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@kernel.org> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> --- block/blk-mq.c | 18 ++++++++---------- block/blk-timeout.c | 1 + include/linux/blkdev.h | 2 ++ 3 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c index 88baa82..47e722b 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -607,14 +607,12 @@ void blk_mq_complete_request(struct request *rq) */ if (!(hctx->flags & BLK_MQ_F_BLOCKING)) { rcu_read_lock(); - 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); rcu_read_unlock(); } else { srcu_idx = srcu_read_lock(hctx->queue_rq_srcu); - 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); srcu_read_unlock(hctx->queue_rq_srcu, srcu_idx); } @@ -665,8 +663,6 @@ 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)) { /* @@ -817,6 +813,8 @@ 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); @@ -832,7 +830,6 @@ 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; @@ -851,7 +848,8 @@ 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 */ @@ -886,8 +884,8 @@ 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 2d6fd11..13186a7 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -123,6 +123,8 @@ typedef __u32 __bitwise req_flags_t; /* Look at ->special_vec for the actual data payload instead of the bio chain. */ #define RQF_SPECIAL_PAYLOAD ((__force req_flags_t)(1 << 18)) +/* timeout is expired */ +#define RQF_MQ_TIMEOUT_EXPIRED ((__force req_flags_t)(1 << 19)) /* flags that prevent us from merging requests: */ #define RQF_NOMERGE_FLAGS \ -- 2.9.5
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