diff options
Diffstat (limited to 'block/blk-mq-tag.c')
| -rw-r--r-- | block/blk-mq-tag.c | 683 |
1 files changed, 683 insertions, 0 deletions
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c new file mode 100644 index 000000000..cc57e2dd9 --- /dev/null +++ b/block/blk-mq-tag.c @@ -0,0 +1,683 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Tag allocation using scalable bitmaps. Uses active queue tracking to support + * fairer distribution of tags between multiple submitters when a shared tag map + * is used. + * + * Copyright (C) 2013-2014 Jens Axboe + */ +#include <linux/kernel.h> +#include <linux/module.h> + +#include <linux/delay.h> +#include "blk.h" +#include "blk-mq.h" +#include "blk-mq-sched.h" + +/* + * Recalculate wakeup batch when tag is shared by hctx. + */ +static void blk_mq_update_wake_batch(struct blk_mq_tags *tags, + unsigned int users) +{ + if (!users) + return; + + sbitmap_queue_recalculate_wake_batch(&tags->bitmap_tags, + users); + sbitmap_queue_recalculate_wake_batch(&tags->breserved_tags, + users); +} + +/* + * If a previously inactive queue goes active, bump the active user count. + * We need to do this before try to allocate driver tag, then even if fail + * to get tag when first time, the other shared-tag users could reserve + * budget for it. + */ +void __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) +{ + unsigned int users; + struct blk_mq_tags *tags = hctx->tags; + + /* + * calling test_bit() prior to test_and_set_bit() is intentional, + * it avoids dirtying the cacheline if the queue is already active. + */ + if (blk_mq_is_shared_tags(hctx->flags)) { + struct request_queue *q = hctx->queue; + + if (test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags) || + test_and_set_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags)) + return; + } else { + if (test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) || + test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) + return; + } + + spin_lock_irq(&tags->lock); + users = tags->active_queues + 1; + WRITE_ONCE(tags->active_queues, users); + blk_mq_update_wake_batch(tags, users); + spin_unlock_irq(&tags->lock); +} + +/* + * Wakeup all potentially sleeping on tags + */ +void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) +{ + sbitmap_queue_wake_all(&tags->bitmap_tags); + if (include_reserve) + sbitmap_queue_wake_all(&tags->breserved_tags); +} + +/* + * If a previously busy queue goes inactive, potential waiters could now + * be allowed to queue. Wake them up and check. + */ +void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) +{ + struct blk_mq_tags *tags = hctx->tags; + unsigned int users; + + if (blk_mq_is_shared_tags(hctx->flags)) { + struct request_queue *q = hctx->queue; + + if (!test_and_clear_bit(QUEUE_FLAG_HCTX_ACTIVE, + &q->queue_flags)) + return; + } else { + if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) + return; + } + + spin_lock_irq(&tags->lock); + users = tags->active_queues - 1; + WRITE_ONCE(tags->active_queues, users); + blk_mq_update_wake_batch(tags, users); + spin_unlock_irq(&tags->lock); + + blk_mq_tag_wakeup_all(tags, false); +} + +static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, + struct sbitmap_queue *bt) +{ + if (!data->q->elevator && !(data->flags & BLK_MQ_REQ_RESERVED) && + !hctx_may_queue(data->hctx, bt)) + return BLK_MQ_NO_TAG; + + if (data->shallow_depth) + return sbitmap_queue_get_shallow(bt, data->shallow_depth); + else + return __sbitmap_queue_get(bt); +} + +unsigned long blk_mq_get_tags(struct blk_mq_alloc_data *data, int nr_tags, + unsigned int *offset) +{ + struct blk_mq_tags *tags = blk_mq_tags_from_data(data); + struct sbitmap_queue *bt = &tags->bitmap_tags; + unsigned long ret; + + if (data->shallow_depth ||data->flags & BLK_MQ_REQ_RESERVED || + data->hctx->flags & BLK_MQ_F_TAG_QUEUE_SHARED) + return 0; + ret = __sbitmap_queue_get_batch(bt, nr_tags, offset); + *offset += tags->nr_reserved_tags; + return ret; +} + +unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) +{ + struct blk_mq_tags *tags = blk_mq_tags_from_data(data); + struct sbitmap_queue *bt; + struct sbq_wait_state *ws; + DEFINE_SBQ_WAIT(wait); + unsigned int tag_offset; + int tag; + + if (data->flags & BLK_MQ_REQ_RESERVED) { + if (unlikely(!tags->nr_reserved_tags)) { + WARN_ON_ONCE(1); + return BLK_MQ_NO_TAG; + } + bt = &tags->breserved_tags; + tag_offset = 0; + } else { + bt = &tags->bitmap_tags; + tag_offset = tags->nr_reserved_tags; + } + + tag = __blk_mq_get_tag(data, bt); + if (tag != BLK_MQ_NO_TAG) + goto found_tag; + + if (data->flags & BLK_MQ_REQ_NOWAIT) + return BLK_MQ_NO_TAG; + + ws = bt_wait_ptr(bt, data->hctx); + do { + struct sbitmap_queue *bt_prev; + + /* + * We're out of tags on this hardware queue, kick any + * pending IO submits before going to sleep waiting for + * some to complete. + */ + blk_mq_run_hw_queue(data->hctx, false); + + /* + * Retry tag allocation after running the hardware queue, + * as running the queue may also have found completions. + */ + tag = __blk_mq_get_tag(data, bt); + if (tag != BLK_MQ_NO_TAG) + break; + + sbitmap_prepare_to_wait(bt, ws, &wait, TASK_UNINTERRUPTIBLE); + + tag = __blk_mq_get_tag(data, bt); + if (tag != BLK_MQ_NO_TAG) + break; + + bt_prev = bt; + io_schedule(); + + sbitmap_finish_wait(bt, ws, &wait); + + data->ctx = blk_mq_get_ctx(data->q); + data->hctx = blk_mq_map_queue(data->q, data->cmd_flags, + data->ctx); + tags = blk_mq_tags_from_data(data); + if (data->flags & BLK_MQ_REQ_RESERVED) + bt = &tags->breserved_tags; + else + bt = &tags->bitmap_tags; + + /* + * If destination hw queue is changed, fake wake up on + * previous queue for compensating the wake up miss, so + * other allocations on previous queue won't be starved. + */ + if (bt != bt_prev) + sbitmap_queue_wake_up(bt_prev, 1); + + ws = bt_wait_ptr(bt, data->hctx); + } while (1); + + sbitmap_finish_wait(bt, ws, &wait); + +found_tag: + /* + * Give up this allocation if the hctx is inactive. The caller will + * retry on an active hctx. + */ + if (unlikely(test_bit(BLK_MQ_S_INACTIVE, &data->hctx->state))) { + blk_mq_put_tag(tags, data->ctx, tag + tag_offset); + return BLK_MQ_NO_TAG; + } + return tag + tag_offset; +} + +void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx, + unsigned int tag) +{ + if (!blk_mq_tag_is_reserved(tags, tag)) { + const int real_tag = tag - tags->nr_reserved_tags; + + BUG_ON(real_tag >= tags->nr_tags); + sbitmap_queue_clear(&tags->bitmap_tags, real_tag, ctx->cpu); + } else { + sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu); + } +} + +void blk_mq_put_tags(struct blk_mq_tags *tags, int *tag_array, int nr_tags) +{ + sbitmap_queue_clear_batch(&tags->bitmap_tags, tags->nr_reserved_tags, + tag_array, nr_tags); +} + +struct bt_iter_data { + struct blk_mq_hw_ctx *hctx; + struct request_queue *q; + busy_tag_iter_fn *fn; + void *data; + bool reserved; +}; + +static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags, + unsigned int bitnr) +{ + struct request *rq; + unsigned long flags; + + spin_lock_irqsave(&tags->lock, flags); + rq = tags->rqs[bitnr]; + if (!rq || rq->tag != bitnr || !req_ref_inc_not_zero(rq)) + rq = NULL; + spin_unlock_irqrestore(&tags->lock, flags); + return rq; +} + +static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) +{ + struct bt_iter_data *iter_data = data; + struct blk_mq_hw_ctx *hctx = iter_data->hctx; + struct request_queue *q = iter_data->q; + struct blk_mq_tag_set *set = q->tag_set; + struct blk_mq_tags *tags; + struct request *rq; + bool ret = true; + + if (blk_mq_is_shared_tags(set->flags)) + tags = set->shared_tags; + else + tags = hctx->tags; + + if (!iter_data->reserved) + bitnr += tags->nr_reserved_tags; + /* + * We can hit rq == NULL here, because the tagging functions + * test and set the bit before assigning ->rqs[]. + */ + rq = blk_mq_find_and_get_req(tags, bitnr); + if (!rq) + return true; + + if (rq->q == q && (!hctx || rq->mq_hctx == hctx)) + ret = iter_data->fn(rq, iter_data->data); + blk_mq_put_rq_ref(rq); + return ret; +} + +/** + * bt_for_each - iterate over the requests associated with a hardware queue + * @hctx: Hardware queue to examine. + * @q: Request queue to examine. + * @bt: sbitmap to examine. This is either the breserved_tags member + * or the bitmap_tags member of struct blk_mq_tags. + * @fn: Pointer to the function that will be called for each request + * associated with @hctx that has been assigned a driver tag. + * @fn will be called as follows: @fn(@hctx, rq, @data, @reserved) + * where rq is a pointer to a request. Return true to continue + * iterating tags, false to stop. + * @data: Will be passed as third argument to @fn. + * @reserved: Indicates whether @bt is the breserved_tags member or the + * bitmap_tags member of struct blk_mq_tags. + */ +static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct request_queue *q, + struct sbitmap_queue *bt, busy_tag_iter_fn *fn, + void *data, bool reserved) +{ + struct bt_iter_data iter_data = { + .hctx = hctx, + .fn = fn, + .data = data, + .reserved = reserved, + .q = q, + }; + + sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data); +} + +struct bt_tags_iter_data { + struct blk_mq_tags *tags; + busy_tag_iter_fn *fn; + void *data; + unsigned int flags; +}; + +#define BT_TAG_ITER_RESERVED (1 << 0) +#define BT_TAG_ITER_STARTED (1 << 1) +#define BT_TAG_ITER_STATIC_RQS (1 << 2) + +static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) +{ + struct bt_tags_iter_data *iter_data = data; + struct blk_mq_tags *tags = iter_data->tags; + struct request *rq; + bool ret = true; + bool iter_static_rqs = !!(iter_data->flags & BT_TAG_ITER_STATIC_RQS); + + if (!(iter_data->flags & BT_TAG_ITER_RESERVED)) + bitnr += tags->nr_reserved_tags; + + /* + * We can hit rq == NULL here, because the tagging functions + * test and set the bit before assigning ->rqs[]. + */ + if (iter_static_rqs) + rq = tags->static_rqs[bitnr]; + else + rq = blk_mq_find_and_get_req(tags, bitnr); + if (!rq) + return true; + + if (!(iter_data->flags & BT_TAG_ITER_STARTED) || + blk_mq_request_started(rq)) + ret = iter_data->fn(rq, iter_data->data); + if (!iter_static_rqs) + blk_mq_put_rq_ref(rq); + return ret; +} + +/** + * bt_tags_for_each - iterate over the requests in a tag map + * @tags: Tag map to iterate over. + * @bt: sbitmap to examine. This is either the breserved_tags member + * or the bitmap_tags member of struct blk_mq_tags. + * @fn: Pointer to the function that will be called for each started + * request. @fn will be called as follows: @fn(rq, @data, + * @reserved) where rq is a pointer to a request. Return true + * to continue iterating tags, false to stop. + * @data: Will be passed as second argument to @fn. + * @flags: BT_TAG_ITER_* + */ +static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, + busy_tag_iter_fn *fn, void *data, unsigned int flags) +{ + struct bt_tags_iter_data iter_data = { + .tags = tags, + .fn = fn, + .data = data, + .flags = flags, + }; + + if (tags->rqs) + sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data); +} + +static void __blk_mq_all_tag_iter(struct blk_mq_tags *tags, + busy_tag_iter_fn *fn, void *priv, unsigned int flags) +{ + WARN_ON_ONCE(flags & BT_TAG_ITER_RESERVED); + + if (tags->nr_reserved_tags) + bt_tags_for_each(tags, &tags->breserved_tags, fn, priv, + flags | BT_TAG_ITER_RESERVED); + bt_tags_for_each(tags, &tags->bitmap_tags, fn, priv, flags); +} + +/** + * blk_mq_all_tag_iter - iterate over all requests in a tag map + * @tags: Tag map to iterate over. + * @fn: Pointer to the function that will be called for each + * request. @fn will be called as follows: @fn(rq, @priv, + * reserved) where rq is a pointer to a request. 'reserved' + * indicates whether or not @rq is a reserved request. Return + * true to continue iterating tags, false to stop. + * @priv: Will be passed as second argument to @fn. + * + * Caller has to pass the tag map from which requests are allocated. + */ +void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, + void *priv) +{ + __blk_mq_all_tag_iter(tags, fn, priv, BT_TAG_ITER_STATIC_RQS); +} + +/** + * blk_mq_tagset_busy_iter - iterate over all started requests in a tag set + * @tagset: Tag set to iterate over. + * @fn: Pointer to the function that will be called for each started + * request. @fn will be called as follows: @fn(rq, @priv, + * reserved) where rq is a pointer to a request. 'reserved' + * indicates whether or not @rq is a reserved request. Return + * true to continue iterating tags, false to stop. + * @priv: Will be passed as second argument to @fn. + * + * We grab one request reference before calling @fn and release it after + * @fn returns. + */ +void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, + busy_tag_iter_fn *fn, void *priv) +{ + unsigned int flags = tagset->flags; + int i, nr_tags; + + nr_tags = blk_mq_is_shared_tags(flags) ? 1 : tagset->nr_hw_queues; + + for (i = 0; i < nr_tags; i++) { + if (tagset->tags && tagset->tags[i]) + __blk_mq_all_tag_iter(tagset->tags[i], fn, priv, + BT_TAG_ITER_STARTED); + } +} +EXPORT_SYMBOL(blk_mq_tagset_busy_iter); + +static bool blk_mq_tagset_count_completed_rqs(struct request *rq, void *data) +{ + unsigned *count = data; + + if (blk_mq_request_completed(rq)) + (*count)++; + return true; +} + +/** + * blk_mq_tagset_wait_completed_request - Wait until all scheduled request + * completions have finished. + * @tagset: Tag set to drain completed request + * + * Note: This function has to be run after all IO queues are shutdown + */ +void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset) +{ + while (true) { + unsigned count = 0; + + blk_mq_tagset_busy_iter(tagset, + blk_mq_tagset_count_completed_rqs, &count); + if (!count) + break; + msleep(5); + } +} +EXPORT_SYMBOL(blk_mq_tagset_wait_completed_request); + +/** + * blk_mq_queue_tag_busy_iter - iterate over all requests with a driver tag + * @q: Request queue to examine. + * @fn: Pointer to the function that will be called for each request + * on @q. @fn will be called as follows: @fn(hctx, rq, @priv, + * reserved) where rq is a pointer to a request and hctx points + * to the hardware queue associated with the request. 'reserved' + * indicates whether or not @rq is a reserved request. + * @priv: Will be passed as third argument to @fn. + * + * Note: if @q->tag_set is shared with other request queues then @fn will be + * called for all requests on all queues that share that tag set and not only + * for requests associated with @q. + */ +void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_tag_iter_fn *fn, + void *priv) +{ + /* + * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and hctx_table + * while the queue is frozen. So we can use q_usage_counter to avoid + * racing with it. + */ + if (!percpu_ref_tryget(&q->q_usage_counter)) + return; + + if (blk_mq_is_shared_tags(q->tag_set->flags)) { + struct blk_mq_tags *tags = q->tag_set->shared_tags; + struct sbitmap_queue *bresv = &tags->breserved_tags; + struct sbitmap_queue *btags = &tags->bitmap_tags; + + if (tags->nr_reserved_tags) + bt_for_each(NULL, q, bresv, fn, priv, true); + bt_for_each(NULL, q, btags, fn, priv, false); + } else { + struct blk_mq_hw_ctx *hctx; + unsigned long i; + + queue_for_each_hw_ctx(q, hctx, i) { + struct blk_mq_tags *tags = hctx->tags; + struct sbitmap_queue *bresv = &tags->breserved_tags; + struct sbitmap_queue *btags = &tags->bitmap_tags; + + /* + * If no software queues are currently mapped to this + * hardware queue, there's nothing to check + */ + if (!blk_mq_hw_queue_mapped(hctx)) + continue; + + if (tags->nr_reserved_tags) + bt_for_each(hctx, q, bresv, fn, priv, true); + bt_for_each(hctx, q, btags, fn, priv, false); + } + } + blk_queue_exit(q); +} + +static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, + bool round_robin, int node) +{ + return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL, + node); +} + +int blk_mq_init_bitmaps(struct sbitmap_queue *bitmap_tags, + struct sbitmap_queue *breserved_tags, + unsigned int queue_depth, unsigned int reserved, + int node, int alloc_policy) +{ + unsigned int depth = queue_depth - reserved; + bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; + + if (bt_alloc(bitmap_tags, depth, round_robin, node)) + return -ENOMEM; + if (bt_alloc(breserved_tags, reserved, round_robin, node)) + goto free_bitmap_tags; + + return 0; + +free_bitmap_tags: + sbitmap_queue_free(bitmap_tags); + return -ENOMEM; +} + +struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, + unsigned int reserved_tags, + int node, int alloc_policy) +{ + struct blk_mq_tags *tags; + + if (total_tags > BLK_MQ_TAG_MAX) { + pr_err("blk-mq: tag depth too large\n"); + return NULL; + } + + tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); + if (!tags) + return NULL; + + tags->nr_tags = total_tags; + tags->nr_reserved_tags = reserved_tags; + spin_lock_init(&tags->lock); + + if (blk_mq_init_bitmaps(&tags->bitmap_tags, &tags->breserved_tags, + total_tags, reserved_tags, node, + alloc_policy) < 0) { + kfree(tags); + return NULL; + } + return tags; +} + +void blk_mq_free_tags(struct blk_mq_tags *tags) +{ + sbitmap_queue_free(&tags->bitmap_tags); + sbitmap_queue_free(&tags->breserved_tags); + kfree(tags); +} + +int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, + struct blk_mq_tags **tagsptr, unsigned int tdepth, + bool can_grow) +{ + struct blk_mq_tags *tags = *tagsptr; + + if (tdepth <= tags->nr_reserved_tags) + return -EINVAL; + + /* + * If we are allowed to grow beyond the original size, allocate + * a new set of tags before freeing the old one. + */ + if (tdepth > tags->nr_tags) { + struct blk_mq_tag_set *set = hctx->queue->tag_set; + struct blk_mq_tags *new; + + if (!can_grow) + return -EINVAL; + + /* + * We need some sort of upper limit, set it high enough that + * no valid use cases should require more. + */ + if (tdepth > MAX_SCHED_RQ) + return -EINVAL; + + /* + * Only the sbitmap needs resizing since we allocated the max + * initially. + */ + if (blk_mq_is_shared_tags(set->flags)) + return 0; + + new = blk_mq_alloc_map_and_rqs(set, hctx->queue_num, tdepth); + if (!new) + return -ENOMEM; + + blk_mq_free_map_and_rqs(set, *tagsptr, hctx->queue_num); + *tagsptr = new; + } else { + /* + * Don't need (or can't) update reserved tags here, they + * remain static and should never need resizing. + */ + sbitmap_queue_resize(&tags->bitmap_tags, + tdepth - tags->nr_reserved_tags); + } + + return 0; +} + +void blk_mq_tag_resize_shared_tags(struct blk_mq_tag_set *set, unsigned int size) +{ + struct blk_mq_tags *tags = set->shared_tags; + + sbitmap_queue_resize(&tags->bitmap_tags, size - set->reserved_tags); +} + +void blk_mq_tag_update_sched_shared_tags(struct request_queue *q) +{ + sbitmap_queue_resize(&q->sched_shared_tags->bitmap_tags, + q->nr_requests - q->tag_set->reserved_tags); +} + +/** + * blk_mq_unique_tag() - return a tag that is unique queue-wide + * @rq: request for which to compute a unique tag + * + * The tag field in struct request is unique per hardware queue but not over + * all hardware queues. Hence this function that returns a tag with the + * hardware context index in the upper bits and the per hardware queue tag in + * the lower bits. + * + * Note: When called for a request that is queued on a non-multiqueue request + * queue, the hardware context index is set to zero. + */ +u32 blk_mq_unique_tag(struct request *rq) +{ + return (rq->mq_hctx->queue_num << BLK_MQ_UNIQUE_TAG_BITS) | + (rq->tag & BLK_MQ_UNIQUE_TAG_MASK); +} +EXPORT_SYMBOL(blk_mq_unique_tag); |