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654 lines
18 KiB
654 lines
18 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Tag allocation using scalable bitmaps. Uses active queue tracking to support |
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* fairer distribution of tags between multiple submitters when a shared tag map |
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* is used. |
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* |
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* Copyright (C) 2013-2014 Jens Axboe |
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*/ |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/blk-mq.h> |
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#include <linux/delay.h> |
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#include "blk.h" |
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#include "blk-mq.h" |
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#include "blk-mq-sched.h" |
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#include "blk-mq-tag.h" |
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|
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/* |
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* If a previously inactive queue goes active, bump the active user count. |
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* We need to do this before try to allocate driver tag, then even if fail |
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* to get tag when first time, the other shared-tag users could reserve |
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* budget for it. |
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*/ |
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bool __blk_mq_tag_busy(struct blk_mq_hw_ctx *hctx) |
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{ |
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if (blk_mq_is_sbitmap_shared(hctx->flags)) { |
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struct request_queue *q = hctx->queue; |
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struct blk_mq_tag_set *set = q->tag_set; |
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if (!test_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags) && |
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!test_and_set_bit(QUEUE_FLAG_HCTX_ACTIVE, &q->queue_flags)) |
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atomic_inc(&set->active_queues_shared_sbitmap); |
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} else { |
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if (!test_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state) && |
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!test_and_set_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
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atomic_inc(&hctx->tags->active_queues); |
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} |
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return true; |
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} |
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/* |
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* Wakeup all potentially sleeping on tags |
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*/ |
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void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool include_reserve) |
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{ |
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sbitmap_queue_wake_all(tags->bitmap_tags); |
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if (include_reserve) |
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sbitmap_queue_wake_all(tags->breserved_tags); |
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} |
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/* |
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* If a previously busy queue goes inactive, potential waiters could now |
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* be allowed to queue. Wake them up and check. |
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*/ |
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void __blk_mq_tag_idle(struct blk_mq_hw_ctx *hctx) |
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{ |
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struct blk_mq_tags *tags = hctx->tags; |
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struct request_queue *q = hctx->queue; |
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struct blk_mq_tag_set *set = q->tag_set; |
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if (blk_mq_is_sbitmap_shared(hctx->flags)) { |
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if (!test_and_clear_bit(QUEUE_FLAG_HCTX_ACTIVE, |
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&q->queue_flags)) |
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return; |
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atomic_dec(&set->active_queues_shared_sbitmap); |
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} else { |
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if (!test_and_clear_bit(BLK_MQ_S_TAG_ACTIVE, &hctx->state)) |
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return; |
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atomic_dec(&tags->active_queues); |
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} |
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blk_mq_tag_wakeup_all(tags, false); |
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} |
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static int __blk_mq_get_tag(struct blk_mq_alloc_data *data, |
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struct sbitmap_queue *bt) |
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{ |
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if (!data->q->elevator && !(data->flags & BLK_MQ_REQ_RESERVED) && |
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!hctx_may_queue(data->hctx, bt)) |
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return BLK_MQ_NO_TAG; |
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if (data->shallow_depth) |
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return __sbitmap_queue_get_shallow(bt, data->shallow_depth); |
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else |
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return __sbitmap_queue_get(bt); |
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} |
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unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data) |
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{ |
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struct blk_mq_tags *tags = blk_mq_tags_from_data(data); |
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struct sbitmap_queue *bt; |
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struct sbq_wait_state *ws; |
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DEFINE_SBQ_WAIT(wait); |
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unsigned int tag_offset; |
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int tag; |
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if (data->flags & BLK_MQ_REQ_RESERVED) { |
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if (unlikely(!tags->nr_reserved_tags)) { |
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WARN_ON_ONCE(1); |
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return BLK_MQ_NO_TAG; |
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} |
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bt = tags->breserved_tags; |
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tag_offset = 0; |
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} else { |
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bt = tags->bitmap_tags; |
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tag_offset = tags->nr_reserved_tags; |
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} |
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tag = __blk_mq_get_tag(data, bt); |
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if (tag != BLK_MQ_NO_TAG) |
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goto found_tag; |
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if (data->flags & BLK_MQ_REQ_NOWAIT) |
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return BLK_MQ_NO_TAG; |
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ws = bt_wait_ptr(bt, data->hctx); |
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do { |
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struct sbitmap_queue *bt_prev; |
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/* |
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* We're out of tags on this hardware queue, kick any |
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* pending IO submits before going to sleep waiting for |
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* some to complete. |
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*/ |
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blk_mq_run_hw_queue(data->hctx, false); |
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/* |
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* Retry tag allocation after running the hardware queue, |
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* as running the queue may also have found completions. |
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*/ |
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tag = __blk_mq_get_tag(data, bt); |
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if (tag != BLK_MQ_NO_TAG) |
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break; |
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sbitmap_prepare_to_wait(bt, ws, &wait, TASK_UNINTERRUPTIBLE); |
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tag = __blk_mq_get_tag(data, bt); |
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if (tag != BLK_MQ_NO_TAG) |
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break; |
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bt_prev = bt; |
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io_schedule(); |
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sbitmap_finish_wait(bt, ws, &wait); |
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data->ctx = blk_mq_get_ctx(data->q); |
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data->hctx = blk_mq_map_queue(data->q, data->cmd_flags, |
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data->ctx); |
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tags = blk_mq_tags_from_data(data); |
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if (data->flags & BLK_MQ_REQ_RESERVED) |
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bt = tags->breserved_tags; |
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else |
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bt = tags->bitmap_tags; |
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/* |
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* If destination hw queue is changed, fake wake up on |
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* previous queue for compensating the wake up miss, so |
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* other allocations on previous queue won't be starved. |
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*/ |
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if (bt != bt_prev) |
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sbitmap_queue_wake_up(bt_prev); |
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ws = bt_wait_ptr(bt, data->hctx); |
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} while (1); |
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sbitmap_finish_wait(bt, ws, &wait); |
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found_tag: |
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/* |
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* Give up this allocation if the hctx is inactive. The caller will |
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* retry on an active hctx. |
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*/ |
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if (unlikely(test_bit(BLK_MQ_S_INACTIVE, &data->hctx->state))) { |
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blk_mq_put_tag(tags, data->ctx, tag + tag_offset); |
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return BLK_MQ_NO_TAG; |
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} |
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return tag + tag_offset; |
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} |
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void blk_mq_put_tag(struct blk_mq_tags *tags, struct blk_mq_ctx *ctx, |
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unsigned int tag) |
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{ |
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if (!blk_mq_tag_is_reserved(tags, tag)) { |
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const int real_tag = tag - tags->nr_reserved_tags; |
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BUG_ON(real_tag >= tags->nr_tags); |
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sbitmap_queue_clear(tags->bitmap_tags, real_tag, ctx->cpu); |
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} else { |
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BUG_ON(tag >= tags->nr_reserved_tags); |
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sbitmap_queue_clear(tags->breserved_tags, tag, ctx->cpu); |
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} |
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} |
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struct bt_iter_data { |
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struct blk_mq_hw_ctx *hctx; |
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busy_iter_fn *fn; |
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void *data; |
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bool reserved; |
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}; |
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static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags, |
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unsigned int bitnr) |
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{ |
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struct request *rq; |
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unsigned long flags; |
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spin_lock_irqsave(&tags->lock, flags); |
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rq = tags->rqs[bitnr]; |
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if (!rq || rq->tag != bitnr || !refcount_inc_not_zero(&rq->ref)) |
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rq = NULL; |
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spin_unlock_irqrestore(&tags->lock, flags); |
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return rq; |
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} |
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static bool bt_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) |
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{ |
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struct bt_iter_data *iter_data = data; |
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struct blk_mq_hw_ctx *hctx = iter_data->hctx; |
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struct blk_mq_tags *tags = hctx->tags; |
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bool reserved = iter_data->reserved; |
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struct request *rq; |
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bool ret = true; |
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if (!reserved) |
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bitnr += tags->nr_reserved_tags; |
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/* |
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* We can hit rq == NULL here, because the tagging functions |
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* test and set the bit before assigning ->rqs[]. |
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*/ |
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rq = blk_mq_find_and_get_req(tags, bitnr); |
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if (!rq) |
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return true; |
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if (rq->q == hctx->queue && rq->mq_hctx == hctx) |
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ret = iter_data->fn(hctx, rq, iter_data->data, reserved); |
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blk_mq_put_rq_ref(rq); |
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return ret; |
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} |
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/** |
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* bt_for_each - iterate over the requests associated with a hardware queue |
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* @hctx: Hardware queue to examine. |
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* @bt: sbitmap to examine. This is either the breserved_tags member |
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* or the bitmap_tags member of struct blk_mq_tags. |
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* @fn: Pointer to the function that will be called for each request |
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* associated with @hctx that has been assigned a driver tag. |
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* @fn will be called as follows: @fn(@hctx, rq, @data, @reserved) |
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* where rq is a pointer to a request. Return true to continue |
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* iterating tags, false to stop. |
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* @data: Will be passed as third argument to @fn. |
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* @reserved: Indicates whether @bt is the breserved_tags member or the |
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* bitmap_tags member of struct blk_mq_tags. |
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*/ |
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static void bt_for_each(struct blk_mq_hw_ctx *hctx, struct sbitmap_queue *bt, |
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busy_iter_fn *fn, void *data, bool reserved) |
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{ |
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struct bt_iter_data iter_data = { |
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.hctx = hctx, |
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.fn = fn, |
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.data = data, |
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.reserved = reserved, |
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}; |
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sbitmap_for_each_set(&bt->sb, bt_iter, &iter_data); |
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} |
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struct bt_tags_iter_data { |
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struct blk_mq_tags *tags; |
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busy_tag_iter_fn *fn; |
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void *data; |
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unsigned int flags; |
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}; |
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#define BT_TAG_ITER_RESERVED (1 << 0) |
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#define BT_TAG_ITER_STARTED (1 << 1) |
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#define BT_TAG_ITER_STATIC_RQS (1 << 2) |
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static bool bt_tags_iter(struct sbitmap *bitmap, unsigned int bitnr, void *data) |
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{ |
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struct bt_tags_iter_data *iter_data = data; |
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struct blk_mq_tags *tags = iter_data->tags; |
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bool reserved = iter_data->flags & BT_TAG_ITER_RESERVED; |
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struct request *rq; |
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bool ret = true; |
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bool iter_static_rqs = !!(iter_data->flags & BT_TAG_ITER_STATIC_RQS); |
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if (!reserved) |
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bitnr += tags->nr_reserved_tags; |
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/* |
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* We can hit rq == NULL here, because the tagging functions |
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* test and set the bit before assigning ->rqs[]. |
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*/ |
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if (iter_static_rqs) |
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rq = tags->static_rqs[bitnr]; |
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else |
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rq = blk_mq_find_and_get_req(tags, bitnr); |
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if (!rq) |
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return true; |
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if (!(iter_data->flags & BT_TAG_ITER_STARTED) || |
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blk_mq_request_started(rq)) |
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ret = iter_data->fn(rq, iter_data->data, reserved); |
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if (!iter_static_rqs) |
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blk_mq_put_rq_ref(rq); |
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return ret; |
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} |
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/** |
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* bt_tags_for_each - iterate over the requests in a tag map |
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* @tags: Tag map to iterate over. |
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* @bt: sbitmap to examine. This is either the breserved_tags member |
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* or the bitmap_tags member of struct blk_mq_tags. |
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* @fn: Pointer to the function that will be called for each started |
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* request. @fn will be called as follows: @fn(rq, @data, |
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* @reserved) where rq is a pointer to a request. Return true |
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* to continue iterating tags, false to stop. |
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* @data: Will be passed as second argument to @fn. |
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* @flags: BT_TAG_ITER_* |
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*/ |
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static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, |
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busy_tag_iter_fn *fn, void *data, unsigned int flags) |
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{ |
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struct bt_tags_iter_data iter_data = { |
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.tags = tags, |
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.fn = fn, |
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.data = data, |
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.flags = flags, |
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}; |
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if (tags->rqs) |
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sbitmap_for_each_set(&bt->sb, bt_tags_iter, &iter_data); |
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} |
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static void __blk_mq_all_tag_iter(struct blk_mq_tags *tags, |
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busy_tag_iter_fn *fn, void *priv, unsigned int flags) |
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{ |
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WARN_ON_ONCE(flags & BT_TAG_ITER_RESERVED); |
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if (tags->nr_reserved_tags) |
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bt_tags_for_each(tags, tags->breserved_tags, fn, priv, |
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flags | BT_TAG_ITER_RESERVED); |
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bt_tags_for_each(tags, tags->bitmap_tags, fn, priv, flags); |
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} |
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/** |
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* blk_mq_all_tag_iter - iterate over all requests in a tag map |
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* @tags: Tag map to iterate over. |
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* @fn: Pointer to the function that will be called for each |
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* request. @fn will be called as follows: @fn(rq, @priv, |
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* reserved) where rq is a pointer to a request. 'reserved' |
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* indicates whether or not @rq is a reserved request. Return |
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* true to continue iterating tags, false to stop. |
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* @priv: Will be passed as second argument to @fn. |
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* |
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* Caller has to pass the tag map from which requests are allocated. |
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*/ |
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void blk_mq_all_tag_iter(struct blk_mq_tags *tags, busy_tag_iter_fn *fn, |
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void *priv) |
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{ |
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__blk_mq_all_tag_iter(tags, fn, priv, BT_TAG_ITER_STATIC_RQS); |
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} |
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/** |
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* blk_mq_tagset_busy_iter - iterate over all started requests in a tag set |
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* @tagset: Tag set to iterate over. |
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* @fn: Pointer to the function that will be called for each started |
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* request. @fn will be called as follows: @fn(rq, @priv, |
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* reserved) where rq is a pointer to a request. 'reserved' |
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* indicates whether or not @rq is a reserved request. Return |
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* true to continue iterating tags, false to stop. |
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* @priv: Will be passed as second argument to @fn. |
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* |
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* We grab one request reference before calling @fn and release it after |
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* @fn returns. |
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*/ |
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void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset, |
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busy_tag_iter_fn *fn, void *priv) |
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{ |
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int i; |
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for (i = 0; i < tagset->nr_hw_queues; i++) { |
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if (tagset->tags && tagset->tags[i]) |
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__blk_mq_all_tag_iter(tagset->tags[i], fn, priv, |
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BT_TAG_ITER_STARTED); |
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} |
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} |
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EXPORT_SYMBOL(blk_mq_tagset_busy_iter); |
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static bool blk_mq_tagset_count_completed_rqs(struct request *rq, |
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void *data, bool reserved) |
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{ |
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unsigned *count = data; |
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if (blk_mq_request_completed(rq)) |
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(*count)++; |
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return true; |
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} |
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/** |
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* blk_mq_tagset_wait_completed_request - Wait until all scheduled request |
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* completions have finished. |
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* @tagset: Tag set to drain completed request |
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* |
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* Note: This function has to be run after all IO queues are shutdown |
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*/ |
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void blk_mq_tagset_wait_completed_request(struct blk_mq_tag_set *tagset) |
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{ |
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while (true) { |
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unsigned count = 0; |
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blk_mq_tagset_busy_iter(tagset, |
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blk_mq_tagset_count_completed_rqs, &count); |
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if (!count) |
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break; |
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msleep(5); |
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} |
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} |
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EXPORT_SYMBOL(blk_mq_tagset_wait_completed_request); |
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|
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/** |
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* blk_mq_queue_tag_busy_iter - iterate over all requests with a driver tag |
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* @q: Request queue to examine. |
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* @fn: Pointer to the function that will be called for each request |
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* on @q. @fn will be called as follows: @fn(hctx, rq, @priv, |
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* reserved) where rq is a pointer to a request and hctx points |
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* to the hardware queue associated with the request. 'reserved' |
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* indicates whether or not @rq is a reserved request. |
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* @priv: Will be passed as third argument to @fn. |
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* |
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* Note: if @q->tag_set is shared with other request queues then @fn will be |
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* called for all requests on all queues that share that tag set and not only |
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* for requests associated with @q. |
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*/ |
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void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, |
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void *priv) |
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{ |
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struct blk_mq_hw_ctx *hctx; |
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int i; |
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|
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/* |
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* __blk_mq_update_nr_hw_queues() updates nr_hw_queues and queue_hw_ctx |
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* while the queue is frozen. So we can use q_usage_counter to avoid |
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* racing with it. |
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*/ |
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if (!percpu_ref_tryget(&q->q_usage_counter)) |
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return; |
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queue_for_each_hw_ctx(q, hctx, i) { |
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struct blk_mq_tags *tags = hctx->tags; |
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|
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/* |
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* If no software queues are currently mapped to this |
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* hardware queue, there's nothing to check |
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*/ |
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if (!blk_mq_hw_queue_mapped(hctx)) |
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continue; |
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|
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if (tags->nr_reserved_tags) |
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bt_for_each(hctx, tags->breserved_tags, fn, priv, true); |
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bt_for_each(hctx, tags->bitmap_tags, fn, priv, false); |
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} |
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blk_queue_exit(q); |
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} |
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static int bt_alloc(struct sbitmap_queue *bt, unsigned int depth, |
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bool round_robin, int node) |
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{ |
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return sbitmap_queue_init_node(bt, depth, -1, round_robin, GFP_KERNEL, |
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node); |
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} |
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int blk_mq_init_bitmaps(struct sbitmap_queue *bitmap_tags, |
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struct sbitmap_queue *breserved_tags, |
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unsigned int queue_depth, unsigned int reserved, |
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int node, int alloc_policy) |
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{ |
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unsigned int depth = queue_depth - reserved; |
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bool round_robin = alloc_policy == BLK_TAG_ALLOC_RR; |
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|
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if (bt_alloc(bitmap_tags, depth, round_robin, node)) |
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return -ENOMEM; |
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if (bt_alloc(breserved_tags, reserved, round_robin, node)) |
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goto free_bitmap_tags; |
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return 0; |
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free_bitmap_tags: |
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sbitmap_queue_free(bitmap_tags); |
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return -ENOMEM; |
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} |
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static int blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, |
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int node, int alloc_policy) |
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{ |
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int ret; |
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ret = blk_mq_init_bitmaps(&tags->__bitmap_tags, |
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&tags->__breserved_tags, |
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tags->nr_tags, tags->nr_reserved_tags, |
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node, alloc_policy); |
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if (ret) |
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return ret; |
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tags->bitmap_tags = &tags->__bitmap_tags; |
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tags->breserved_tags = &tags->__breserved_tags; |
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return 0; |
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} |
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int blk_mq_init_shared_sbitmap(struct blk_mq_tag_set *set) |
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{ |
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int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags); |
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int i, ret; |
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ret = blk_mq_init_bitmaps(&set->__bitmap_tags, &set->__breserved_tags, |
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set->queue_depth, set->reserved_tags, |
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set->numa_node, alloc_policy); |
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if (ret) |
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return ret; |
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|
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for (i = 0; i < set->nr_hw_queues; i++) { |
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struct blk_mq_tags *tags = set->tags[i]; |
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|
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tags->bitmap_tags = &set->__bitmap_tags; |
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tags->breserved_tags = &set->__breserved_tags; |
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} |
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return 0; |
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} |
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|
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void blk_mq_exit_shared_sbitmap(struct blk_mq_tag_set *set) |
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{ |
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sbitmap_queue_free(&set->__bitmap_tags); |
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sbitmap_queue_free(&set->__breserved_tags); |
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} |
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|
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struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, |
|
unsigned int reserved_tags, |
|
int node, unsigned int flags) |
|
{ |
|
int alloc_policy = BLK_MQ_FLAG_TO_ALLOC_POLICY(flags); |
|
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_is_sbitmap_shared(flags)) |
|
return tags; |
|
|
|
if (blk_mq_init_bitmap_tags(tags, node, alloc_policy) < 0) { |
|
kfree(tags); |
|
return NULL; |
|
} |
|
return tags; |
|
} |
|
|
|
void blk_mq_free_tags(struct blk_mq_tags *tags, unsigned int flags) |
|
{ |
|
if (!blk_mq_is_sbitmap_shared(flags)) { |
|
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 > MAX_SCHED_RQ) |
|
return -EINVAL; |
|
|
|
new = blk_mq_alloc_rq_map(set, hctx->queue_num, tdepth, |
|
tags->nr_reserved_tags, set->flags); |
|
if (!new) |
|
return -ENOMEM; |
|
ret = blk_mq_alloc_rqs(set, new, hctx->queue_num, tdepth); |
|
if (ret) { |
|
blk_mq_free_rq_map(new, set->flags); |
|
return -ENOMEM; |
|
} |
|
|
|
blk_mq_free_rqs(set, *tagsptr, hctx->queue_num); |
|
blk_mq_free_rq_map(*tagsptr, set->flags); |
|
*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_sbitmap(struct blk_mq_tag_set *set, unsigned int size) |
|
{ |
|
sbitmap_queue_resize(&set->__bitmap_tags, size - 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);
|
|
|