diff options
| -rw-r--r-- | block/bfq-iosched.c | 86 |
1 files changed, 57 insertions, 29 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index ebc264c87a09b..eefd8a4bc9361 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -1858,6 +1858,8 @@ static int bfq_request_merge(struct request_queue *q, struct request **req, return ELEVATOR_NO_MERGE; } +static struct bfq_queue *bfq_init_rq(struct request *rq); + static void bfq_request_merged(struct request_queue *q, struct request *req, enum elv_merge type) { @@ -1866,7 +1868,7 @@ static void bfq_request_merged(struct request_queue *q, struct request *req, blk_rq_pos(req) < blk_rq_pos(container_of(rb_prev(&req->rb_node), struct request, rb_node))) { - struct bfq_queue *bfqq = RQ_BFQQ(req); + struct bfq_queue *bfqq = bfq_init_rq(req); struct bfq_data *bfqd = bfqq->bfqd; struct request *prev, *next_rq; @@ -1894,7 +1896,8 @@ static void bfq_request_merged(struct request_queue *q, struct request *req, static void bfq_requests_merged(struct request_queue *q, struct request *rq, struct request *next) { - struct bfq_queue *bfqq = RQ_BFQQ(rq), *next_bfqq = RQ_BFQQ(next); + struct bfq_queue *bfqq = bfq_init_rq(rq), + *next_bfqq = bfq_init_rq(next); if (!RB_EMPTY_NODE(&rq->rb_node)) goto end; @@ -4540,14 +4543,12 @@ static inline void bfq_update_insert_stats(struct request_queue *q, unsigned int cmd_flags) {} #endif -static void bfq_prepare_request(struct request *rq, struct bio *bio); - static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, bool at_head) { struct request_queue *q = hctx->queue; struct bfq_data *bfqd = q->elevator->elevator_data; - struct bfq_queue *bfqq = RQ_BFQQ(rq); + struct bfq_queue *bfqq; bool idle_timer_disabled = false; unsigned int cmd_flags; @@ -4562,24 +4563,13 @@ static void bfq_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq, blk_mq_sched_request_inserted(rq); spin_lock_irq(&bfqd->lock); + bfqq = bfq_init_rq(rq); if (at_head || blk_rq_is_passthrough(rq)) { if (at_head) list_add(&rq->queuelist, &bfqd->dispatch); else list_add_tail(&rq->queuelist, &bfqd->dispatch); - } else { - if (WARN_ON_ONCE(!bfqq)) { - /* - * This should never happen. Most likely rq is - * a requeued regular request, being - * re-inserted without being first - * re-prepared. Do a prepare, to avoid - * failure. - */ - bfq_prepare_request(rq, rq->bio); - bfqq = RQ_BFQQ(rq); - } - + } else { /* bfqq is assumed to be non null here */ idle_timer_disabled = __bfq_insert_request(bfqd, rq); /* * Update bfqq, because, if a queue merge has occurred @@ -4922,11 +4912,48 @@ static struct bfq_queue *bfq_get_bfqq_handle_split(struct bfq_data *bfqd, } /* - * Allocate bfq data structures associated with this request. + * Only reset private fields. The actual request preparation will be + * performed by bfq_init_rq, when rq is either inserted or merged. See + * comments on bfq_init_rq for the reason behind this delayed + * preparation. */ static void bfq_prepare_request(struct request *rq, struct bio *bio) { + /* + * Regardless of whether we have an icq attached, we have to + * clear the scheduler pointers, as they might point to + * previously allocated bic/bfqq structs. + */ + rq->elv.priv[0] = rq->elv.priv[1] = NULL; +} + +/* + * If needed, init rq, allocate bfq data structures associated with + * rq, and increment reference counters in the destination bfq_queue + * for rq. Return the destination bfq_queue for rq, or NULL is rq is + * not associated with any bfq_queue. + * + * This function is invoked by the functions that perform rq insertion + * or merging. One may have expected the above preparation operations + * to be performed in bfq_prepare_request, and not delayed to when rq + * is inserted or merged. The rationale behind this delayed + * preparation is that, after the prepare_request hook is invoked for + * rq, rq may still be transformed into a request with no icq, i.e., a + * request not associated with any queue. No bfq hook is invoked to + * signal this tranformation. As a consequence, should these + * preparation operations be performed when the prepare_request hook + * is invoked, and should rq be transformed one moment later, bfq + * would end up in an inconsistent state, because it would have + * incremented some queue counters for an rq destined to + * transformation, without any chance to correctly lower these + * counters back. In contrast, no transformation can still happen for + * rq after rq has been inserted or merged. So, it is safe to execute + * these preparation operations when rq is finally inserted or merged. + */ +static struct bfq_queue *bfq_init_rq(struct request *rq) +{ struct request_queue *q = rq->q; + struct bio *bio = rq->bio; struct bfq_data *bfqd = q->elevator->elevator_data; struct bfq_io_cq *bic; const int is_sync = rq_is_sync(rq); @@ -4934,20 +4961,21 @@ static void bfq_prepare_request(struct request *rq, struct bio *bio) bool new_queue = false; bool bfqq_already_existing = false, split = false; + if (unlikely(!rq->elv.icq)) + return NULL; + /* - * Even if we don't have an icq attached, we should still clear - * the scheduler pointers, as they might point to previously - * allocated bic/bfqq structs. + * Assuming that elv.priv[1] is set only if everything is set + * for this rq. This holds true, because this function is + * invoked only for insertion or merging, and, after such + * events, a request cannot be manipulated any longer before + * being removed from bfq. */ - if (!rq->elv.icq) { - rq->elv.priv[0] = rq->elv.priv[1] = NULL; - return; - } + if (rq->elv.priv[1]) + return rq->elv.priv[1]; bic = icq_to_bic(rq->elv.icq); - spin_lock_irq(&bfqd->lock); - bfq_check_ioprio_change(bic, bio); bfq_bic_update_cgroup(bic, bio); @@ -5006,7 +5034,7 @@ static void bfq_prepare_request(struct request *rq, struct bio *bio) if (unlikely(bfq_bfqq_just_created(bfqq))) bfq_handle_burst(bfqd, bfqq); - spin_unlock_irq(&bfqd->lock); + return bfqq; } static void bfq_idle_slice_timer_body(struct bfq_queue *bfqq) |