| // 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/blk-mq.h> |
| #include <linux/delay.h> |
| #include "blk.h" |
| #include "blk-mq.h" |
| #include "blk-mq-tag.h" |
| |
| /* |
| * 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. |
| */ |
| bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) |
| { |
| if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && |
| !test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| atomic_inc(&hctx->tags->active_queues); |
| |
| return true; |
| } |
| |
| /* |
| * 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; |
| |
| if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| return; |
| |
| atomic_dec(&tags->active_queues); |
| |
| blk_mq_tag_wakeup_all(tags, false); |
| } |
| |
| /* |
| * For shared tag users, we track the number of currently active users |
| * and attempt to provide a fair share of the tag depth for each of them. |
| */ |
| static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, |
| struct sbitmap_queue *bt) |
| { |
| unsigned int depth, users; |
| |
| if (!hctx || !(hctx->flags & BLK_MQ_F_TAG_SHARED)) |
| return true; |
| if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
| return true; |
| |
| /* |
| * Don't try dividing an ant |
| */ |
| if (bt->sb.depth == 1) |
| return true; |
| |
| users = atomic_read(&hctx->tags->active_queues); |
| if (!users) |
| return true; |
| |
| /* |
| * Allow at least some tags |
| */ |
| depth = max((bt->sb.depth + users - 1) / users, 4U); |
| return atomic_read(&hctx->nr_active) < depth; |
| } |
| |
| static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, |
| struct sbitmap_queue *bt) |
| { |
| if (!(data->flags & BLK_MQ_REQ_INTERNAL) && |
| !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 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); |
| |
| 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 { |
| BUG_ON(tag >= tags->nr_reserved_tags); |
| sbitmap_queue_clear(&tags->breserved_tags, tag, ctx->cpu); |
| } |
| } |
| |
| struct bt_iter_data { |
| struct blk_mq_hw_ctx *hctx; |
| busy_iter_fn *fn; |
| void *data; |
| bool reserved; |
| }; |
| |
| 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 blk_mq_tags *tags = hctx->tags; |
| bool reserved = iter_data->reserved; |
| struct request *rq; |
| |
| if (!reserved) |
| bitnr += tags->nr_reserved_tags; |
| rq = tags->rqs[bitnr]; |
| |
| /* |
| * We can hit rq == NULL here, because the tagging functions |
| * test and set the bit before assigning ->rqs[]. |
| */ |
| if (rq && rq->q == hctx->queue) |
| return iter_data->fn(hctx, rq, iter_data->data, reserved); |
| return true; |
| } |
| |
| /** |
| * bt_for_each - iterate over the requests associated with a hardware queue |
| * @hctx: Hardware 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 sbitmap_queue *bt, |
| busy_iter_fn *fn, void *data, bool reserved) |
| { |
| struct bt_iter_data iter_data = { |
| .hctx = hctx, |
| .fn = fn, |
| .data = data, |
| .reserved = reserved, |
| }; |
| |
| 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) |
| |
| 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; |
| bool reserved = iter_data->flags & BT_TAG_ITER_RESERVED; |
| struct request *rq; |
| |
| if (!reserved) |
| bitnr += tags->nr_reserved_tags; |
| |
| /* |
| * We can hit rq == NULL here, because the tagging functions |
| * test and set the bit before assining ->rqs[]. |
| */ |
| rq = tags->rqs[bitnr]; |
| if (!rq) |
| return true; |
| if ((iter_data->flags & BT_TAG_ITER_STARTED) && |
| !blk_mq_request_started(rq)) |
| return true; |
| return iter_data->fn(rq, iter_data->data, reserved); |
| } |
| |
| /** |
| * 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. |
| */ |
| void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, |
| void *priv) |
| { |
| return __blk_mq_all_tag_iter(tags, fn, priv, 0); |
| } |
| |
| /** |
| * 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. |
| */ |
| void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |
| busy_tag_iter_fn *fn, void *priv) |
| { |
| int i; |
| |
| for (i = 0; i < tagset->nr_hw_queues; 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, bool reserved) |
| { |
| unsigned *count = data; |
| |
| if (blk_mq_request_completed(rq)) |
| (*count)++; |
| return true; |
| } |
| |
| /** |
| * blk_mq_tagset_wait_completed_request - wait until all completed req's |
| * complete funtion is run |
| * @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_iter_fn *fn, |
| void *priv) |
| { |
| struct blk_mq_hw_ctx *hctx; |
| int i; |
| |
| /* |
| * __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx |
| * while the queue is frozen. So we can use q_usage_counter to avoid |
| * racing with it. __blk_mq_update_nr_hw_queues() uses |
| * synchronize_rcu() to ensure this function left the critical section |
| * below. |
| */ |
| if (!percpu_ref_tryget(&q->q_usage_counter)) |
| return; |
| |
| queue_for_each_hw_ctx(q, hctx, i) { |
| struct blk_mq_tags *tags = hctx->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, &tags->breserved_tags, fn, priv, true); |
| bt_for_each(hctx, &tags->bitmap_tags, 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); |
| } |
| |
| static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, |
| int node, int alloc_policy) |
| { |
| unsigned int depth = tags->nr_tags - tags->nr_reserved_tags; |
| bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; |
| |
| if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node)) |
| goto free_tags; |
| if (bt_alloc(&tags->breserved_tags, tags->nr_reserved_tags, round_robin, |
| node)) |
| goto free_bitmap_tags; |
| |
| return tags; |
| free_bitmap_tags: |
| sbitmap_queue_free(&tags->bitmap_tags); |
| free_tags: |
| kfree(tags); |
| return NULL; |
| } |
| |
| 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; |
| |
| return blk_mq_init_bitmap_tags(tags, node, alloc_policy); |
| } |
| |
| 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; |
| bool ret; |
| |
| 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 > 16 * BLKDEV_MAX_RQ) |
| return -EINVAL; |
| |
| new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth, |
| tags->nr_reserved_tags); |
| if (!new) |
| return -ENOMEM; |
| ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth); |
| if (ret) { |
| blk_mq_free_rq_map(new); |
| return -ENOMEM; |
| } |
| |
| blk_mq_free_rqs(set, *tagsptr, hctx->queue_num); |
| blk_mq_free_rq_map(*tagsptr); |
| *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; |
| } |
| |
| /** |
| * 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); |