diff options
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-core.c | 369 | ||||
| -rw-r--r-- | block/blk-flush.c | 3 | ||||
| -rw-r--r-- | block/elevator.c | 6 |
3 files changed, 277 insertions, 101 deletions
diff --git a/block/blk-core.c b/block/blk-core.c index e958c7a1e462..6efb55cc5af0 100644 --- a/block/blk-core.c +++ b/block/blk-core.c @@ -27,6 +27,7 @@ #include <linux/writeback.h> #include <linux/task_io_accounting_ops.h> #include <linux/fault-inject.h> +#include <linux/list_sort.h> #define CREATE_TRACE_POINTS #include <trace/events/block.h> @@ -203,7 +204,7 @@ static void blk_delay_work(struct work_struct *work) q = container_of(work, struct request_queue, delay_work.work); spin_lock_irq(q->queue_lock); - q->request_fn(q); + __blk_run_queue(q); spin_unlock_irq(q->queue_lock); } @@ -686,6 +687,8 @@ int blk_get_queue(struct request_queue *q) static inline void blk_free_request(struct request_queue *q, struct request *rq) { + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (rq->cmd_flags & REQ_ELVPRIV) elv_put_request(q, rq); mempool_free(rq, q->rq.rq_pool); @@ -1051,6 +1054,13 @@ void blk_requeue_request(struct request_queue *q, struct request *rq) } EXPORT_SYMBOL(blk_requeue_request); +static void add_acct_request(struct request_queue *q, struct request *rq, + int where) +{ + drive_stat_acct(rq, 1); + __elv_add_request(q, rq, where, 0); +} + /** * blk_insert_request - insert a special request into a request queue * @q: request queue where request should be inserted @@ -1093,8 +1103,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq, if (blk_rq_tagged(rq)) blk_queue_end_tag(q, rq); - drive_stat_acct(rq, 1); - __elv_add_request(q, rq, where, 0); + add_acct_request(q, rq, where); __blk_run_queue(q); spin_unlock_irqrestore(q->queue_lock, flags); } @@ -1215,6 +1224,113 @@ void blk_add_request_payload(struct request *rq, struct page *page, } EXPORT_SYMBOL_GPL(blk_add_request_payload); +static bool bio_attempt_back_merge(struct request_queue *q, struct request *req, + struct bio *bio) +{ + const int ff = bio->bi_rw & REQ_FAILFAST_MASK; + + /* + * Debug stuff, kill later + */ + if (!rq_mergeable(req)) { + blk_dump_rq_flags(req, "back"); + return false; + } + + if (!ll_back_merge_fn(q, req, bio)) + return false; + + trace_block_bio_backmerge(q, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + req->biotail->bi_next = bio; + req->biotail = bio; + req->__data_len += bio->bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + drive_stat_acct(req, 0); + return true; +} + +static bool bio_attempt_front_merge(struct request_queue *q, + struct request *req, struct bio *bio) +{ + const int ff = bio->bi_rw & REQ_FAILFAST_MASK; + sector_t sector; + + /* + * Debug stuff, kill later + */ + if (!rq_mergeable(req)) { + blk_dump_rq_flags(req, "front"); + return false; + } + + if (!ll_front_merge_fn(q, req, bio)) + return false; + + trace_block_bio_frontmerge(q, bio); + + if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) + blk_rq_set_mixed_merge(req); + + sector = bio->bi_sector; + + bio->bi_next = req->bio; + req->bio = bio; + + /* + * may not be valid. if the low level driver said + * it didn't need a bounce buffer then it better + * not touch req->buffer either... + */ + req->buffer = bio_data(bio); + req->__sector = bio->bi_sector; + req->__data_len += bio->bi_size; + req->ioprio = ioprio_best(req->ioprio, bio_prio(bio)); + + drive_stat_acct(req, 0); + return true; +} + +/* + * Attempts to merge with the plugged list in the current process. Returns + * true if merge was succesful, otherwise false. + */ +static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q, + struct bio *bio) +{ + struct blk_plug *plug; + struct request *rq; + bool ret = false; + + plug = tsk->plug; + if (!plug) + goto out; + + list_for_each_entry_reverse(rq, &plug->list, queuelist) { + int el_ret; + + if (rq->q != q) + continue; + + el_ret = elv_try_merge(rq, bio); + if (el_ret == ELEVATOR_BACK_MERGE) { + ret = bio_attempt_back_merge(q, rq, bio); + if (ret) + break; + } else if (el_ret == ELEVATOR_FRONT_MERGE) { + ret = bio_attempt_front_merge(q, rq, bio); + if (ret) + break; + } + } +out: + return ret; +} + void init_request_from_bio(struct request *req, struct bio *bio) { req->cpu = bio->bi_comp_cpu; @@ -1230,26 +1346,12 @@ void init_request_from_bio(struct request *req, struct bio *bio) blk_rq_bio_prep(req->q, req, bio); } -/* - * Only disabling plugging for non-rotational devices if it does tagging - * as well, otherwise we do need the proper merging - */ -static inline bool queue_should_plug(struct request_queue *q) -{ - return !(blk_queue_nonrot(q) && blk_queue_tagged(q)); -} - static int __make_request(struct request_queue *q, struct bio *bio) { - struct request *req; - int el_ret; - unsigned int bytes = bio->bi_size; - const unsigned short prio = bio_prio(bio); const bool sync = !!(bio->bi_rw & REQ_SYNC); - const bool unplug = !!(bio->bi_rw & REQ_UNPLUG); - const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK; - int where = ELEVATOR_INSERT_SORT; - int rw_flags; + struct blk_plug *plug; + int el_ret, rw_flags, where = ELEVATOR_INSERT_SORT; + struct request *req; /* * low level driver can indicate that it wants pages above a @@ -1258,78 +1360,36 @@ static int __make_request(struct request_queue *q, struct bio *bio) */ blk_queue_bounce(q, &bio); - spin_lock_irq(q->queue_lock); - if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) { + spin_lock_irq(q->queue_lock); where = ELEVATOR_INSERT_FLUSH; goto get_rq; } - if (elv_queue_empty(q)) - goto get_rq; - - el_ret = elv_merge(q, &req, bio); - switch (el_ret) { - case ELEVATOR_BACK_MERGE: - BUG_ON(!rq_mergeable(req)); - - if (!ll_back_merge_fn(q, req, bio)) - break; - - trace_block_bio_backmerge(q, bio); - - if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) - blk_rq_set_mixed_merge(req); - - req->biotail->bi_next = bio; - req->biotail = bio; - req->__data_len += bytes; - req->ioprio = ioprio_best(req->ioprio, prio); - if (!blk_rq_cpu_valid(req)) - req->cpu = bio->bi_comp_cpu; - drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); - if (!attempt_back_merge(q, req)) - elv_merged_request(q, req, el_ret); + /* + * Check if we can merge with the plugged list before grabbing + * any locks. + */ + if (attempt_plug_merge(current, q, bio)) goto out; - case ELEVATOR_FRONT_MERGE: - BUG_ON(!rq_mergeable(req)); - - if (!ll_front_merge_fn(q, req, bio)) - break; - - trace_block_bio_frontmerge(q, bio); + spin_lock_irq(q->queue_lock); - if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff) { - blk_rq_set_mixed_merge(req); - req->cmd_flags &= ~REQ_FAILFAST_MASK; - req->cmd_flags |= ff; + el_ret = elv_merge(q, &req, bio); + if (el_ret == ELEVATOR_BACK_MERGE) { + BUG_ON(req->cmd_flags & REQ_ON_PLUG); + if (bio_attempt_back_merge(q, req, bio)) { + if (!attempt_back_merge(q, req)) + elv_merged_request(q, req, el_ret); + goto out_unlock; + } + } else if (el_ret == ELEVATOR_FRONT_MERGE) { + BUG_ON(req->cmd_flags & REQ_ON_PLUG); + if (bio_attempt_front_merge(q, req, bio)) { + if (!attempt_front_merge(q, req)) + elv_merged_request(q, req, el_ret); + goto out_unlock; } - - bio->bi_next = req->bio; - req->bio = bio; - - /* - * may not be valid. if the low level driver said - * it didn't need a bounce buffer then it better - * not touch req->buffer either... - */ - req->buffer = bio_data(bio); - req->__sector = bio->bi_sector; - req->__data_len += bytes; - req->ioprio = ioprio_best(req->ioprio, prio); - if (!blk_rq_cpu_valid(req)) - req->cpu = bio->bi_comp_cpu; - drive_stat_acct(req, 0); - elv_bio_merged(q, req, bio); - if (!attempt_front_merge(q, req)) - elv_merged_request(q, req, el_ret); - goto out; - - /* ELV_NO_MERGE: elevator says don't/can't merge. */ - default: - ; } get_rq: @@ -1356,20 +1416,35 @@ get_rq: */ init_request_from_bio(req, bio); - spin_lock_irq(q->queue_lock); if (test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags) || - bio_flagged(bio, BIO_CPU_AFFINE)) - req->cpu = blk_cpu_to_group(smp_processor_id()); - if (queue_should_plug(q) && elv_queue_empty(q)) - blk_plug_device(q); - - /* insert the request into the elevator */ - drive_stat_acct(req, 1); - __elv_add_request(q, req, where, 0); + bio_flagged(bio, BIO_CPU_AFFINE)) { + req->cpu = blk_cpu_to_group(get_cpu()); + put_cpu(); + } + + plug = current->plug; + if (plug && !sync) { + if (!plug->should_sort && !list_empty(&plug->list)) { + struct request *__rq; + + __rq = list_entry_rq(plug->list.prev); + if (__rq->q != q) + plug->should_sort = 1; + } + /* + * Debug flag, kill later + */ + req->cmd_flags |= REQ_ON_PLUG; + list_add_tail(&req->queuelist, &plug->list); + drive_stat_acct(req, 1); + } else { + spin_lock_irq(q->queue_lock); + add_acct_request(q, req, where); + __blk_run_queue(q); +out_unlock: + spin_unlock_irq(q->queue_lock); + } out: - if (unplug || !queue_should_plug(q)) - __generic_unplug_device(q); - spin_unlock_irq(q->queue_lock); return 0; } @@ -1772,9 +1847,7 @@ int blk_insert_cloned_request(struct request_queue *q, struct request *rq) */ BUG_ON(blk_queued_rq(rq)); - drive_stat_acct(rq, 1); - __elv_add_request(q, rq, ELEVATOR_INSERT_BACK, 0); - + add_acct_request(q, rq, ELEVATOR_INSERT_BACK); spin_unlock_irqrestore(q->queue_lock, flags); return 0; @@ -2659,6 +2732,106 @@ int kblockd_schedule_delayed_work(struct request_queue *q, } EXPORT_SYMBOL(kblockd_schedule_delayed_work); +#define PLUG_MAGIC 0x91827364 + +void blk_start_plug(struct blk_plug *plug) +{ + struct task_struct *tsk = current; + + plug->magic = PLUG_MAGIC; + INIT_LIST_HEAD(&plug->list); + plug->should_sort = 0; + + /* + * If this is a nested plug, don't actually assign it. It will be + * flushed on its own. + */ + if (!tsk->plug) { + /* + * Store ordering should not be needed here, since a potential + * preempt will imply a full memory barrier + */ + tsk->plug = plug; + } +} +EXPORT_SYMBOL(blk_start_plug); + +static int plug_rq_cmp(void *priv, struct list_head *a, struct list_head *b) +{ + struct request *rqa = container_of(a, struct request, queuelist); + struct request *rqb = container_of(b, struct request, queuelist); + + return !(rqa->q == rqb->q); +} + +static void flush_plug_list(struct blk_plug *plug) +{ + struct request_queue *q; + unsigned long flags; + struct request *rq; + + BUG_ON(plug->magic != PLUG_MAGIC); + + if (list_empty(&plug->list)) + return; + + if (plug->should_sort) + list_sort(NULL, &plug->list, plug_rq_cmp); + + q = NULL; + local_irq_save(flags); + while (!list_empty(&plug->list)) { + rq = list_entry_rq(plug->list.next); + list_del_init(&rq->queuelist); + BUG_ON(!(rq->cmd_flags & REQ_ON_PLUG)); + BUG_ON(!rq->q); + if (rq->q != q) { + if (q) { + __blk_run_queue(q); + spin_unlock(q->queue_lock); + } + q = rq->q; + spin_lock(q->queue_lock); + } + rq->cmd_flags &= ~REQ_ON_PLUG; + + /* + * rq is already accounted, so use raw insert + */ + __elv_add_request(q, rq, ELEVATOR_INSERT_SORT, 0); + } + + if (q) { + __blk_run_queue(q); + spin_unlock(q->queue_lock); + } + + BUG_ON(!list_empty(&plug->list)); + local_irq_restore(flags); +} + +static void __blk_finish_plug(struct task_struct *tsk, struct blk_plug *plug) +{ + flush_plug_list(plug); + + if (plug == tsk->plug) + tsk->plug = NULL; +} + +void blk_finish_plug(struct blk_plug *plug) +{ + if (plug) + __blk_finish_plug(current, plug); +} +EXPORT_SYMBOL(blk_finish_plug); + +void __blk_flush_plug(struct task_struct *tsk, struct blk_plug *plug) +{ + __blk_finish_plug(tsk, plug); + tsk->plug = plug; +} +EXPORT_SYMBOL(__blk_flush_plug); + int __init blk_dev_init(void) { BUILD_BUG_ON(__REQ_NR_BITS > 8 * diff --git a/block/blk-flush.c b/block/blk-flush.c index a867e3f524f3..1e2aa8a8908c 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -264,10 +264,9 @@ static bool blk_kick_flush(struct request_queue *q) static void flush_data_end_io(struct request *rq, int error) { struct request_queue *q = rq->q; - bool was_empty = elv_queue_empty(q); /* after populating an empty queue, kick it to avoid stall */ - if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error) && was_empty) + if (blk_flush_complete_seq(rq, REQ_FSEQ_DATA, error)) __blk_run_queue(q); } diff --git a/block/elevator.c b/block/elevator.c index f98e92edc937..25713927c0d3 100644 --- a/block/elevator.c +++ b/block/elevator.c @@ -113,7 +113,7 @@ int elv_rq_merge_ok(struct request *rq, struct bio *bio) } EXPORT_SYMBOL(elv_rq_merge_ok); -static inline int elv_try_merge(struct request *__rq, struct bio *bio) +int elv_try_merge(struct request *__rq, struct bio *bio) { int ret = ELEVATOR_NO_MERGE; @@ -421,6 +421,8 @@ void elv_dispatch_sort(struct request_queue *q, struct request *rq) struct list_head *entry; int stop_flags; + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (q->last_merge == rq) q->last_merge = NULL; @@ -696,6 +698,8 @@ void elv_insert(struct request_queue *q, struct request *rq, int where) void __elv_add_request(struct request_queue *q, struct request *rq, int where, int plug) { + BUG_ON(rq->cmd_flags & REQ_ON_PLUG); + if (rq->cmd_flags & REQ_SOFTBARRIER) { /* barriers are scheduling boundary, update end_sector */ if (rq->cmd_type == REQ_TYPE_FS || |