Commit 4e2f62e5 authored by Jens Axboe's avatar Jens Axboe
Browse files

Revert "blk-mq: put driver tag when this request is completed" 

This reverts commits the following commits:

	37f4a24c
	723bf178
	36a3df5a

The last one is the culprit, but we have to go a bit deeper to get this
to revert cleanly. There's been a report that this breaks some MMC
setups [1], and also causes an issue with swap [2]. Until this can be
figured out, revert the offending commits.

[1] https://lore.kernel.org/linux-block/57fb09b1-54ba-f3aa-f82c-d709b0e6b281@samsung.com/
[2] https://lore.kernel.org/linux-block/20200702043721.GA1087@lca.pw/



Reported-by: default avatarMarek Szyprowski <m.szyprowski@samsung.com>
Reported-by: default avatarQian Cai <cai@lca.pw>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent b53ac8b8

block/blk-flush.c

+17 −6
Original line number Diff line number Diff line
@@ -236,10 +236,13 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error) 
		error = fq->rq_status;



	hctx = flush_rq->mq_hctx;

	if (!q->elevator)

		flush_rq->tag = BLK_MQ_NO_TAG;

	else

		flush_rq->internal_tag = BLK_MQ_NO_TAG;

	if (!q->elevator) {

		blk_mq_tag_set_rq(hctx, flush_rq->tag, fq->orig_rq);

		flush_rq->tag = -1;

	} else {

		blk_mq_put_driver_tag(flush_rq);

		flush_rq->internal_tag = -1;

	}



	running = &fq->flush_queue[fq->flush_running_idx];

	BUG_ON(fq->flush_pending_idx == fq->flush_running_idx);
@@ -313,10 +316,13 @@ static void blk_kick_flush(struct request_queue *q, struct blk_flush_queue *fq, 
	flush_rq->mq_ctx = first_rq->mq_ctx;

	flush_rq->mq_hctx = first_rq->mq_hctx;



	if (!q->elevator)

	if (!q->elevator) {

		fq->orig_rq = first_rq;

		flush_rq->tag = first_rq->tag;

	else

		blk_mq_tag_set_rq(flush_rq->mq_hctx, first_rq->tag, flush_rq);

	} else {

		flush_rq->internal_tag = first_rq->internal_tag;

	}



	flush_rq->cmd_flags = REQ_OP_FLUSH | REQ_PREFLUSH;

	flush_rq->cmd_flags |= (flags & REQ_DRV) | (flags & REQ_FAILFAST_MASK);
@@ -335,6 +341,11 @@ static void mq_flush_data_end_io(struct request *rq, blk_status_t error) 
	unsigned long flags;

	struct blk_flush_queue *fq = blk_get_flush_queue(q, ctx);



	if (q->elevator) {

		WARN_ON(rq->tag < 0);

		blk_mq_put_driver_tag(rq);

	}



	/*

	 * After populating an empty queue, kick it to avoid stall.  Read

	 * the comment in flush_end_io().

block/blk-mq-tag.h

+12 −0
Original line number Diff line number Diff line
@@ -101,6 +101,18 @@ static inline bool hctx_may_queue(struct blk_mq_hw_ctx *hctx, 
	return atomic_read(&hctx->nr_active) < depth;

}



/*

 * This helper should only be used for flush request to share tag

 * with the request cloned from, and both the two requests can't be

 * in flight at the same time. The caller has to make sure the tag

 * can't be freed.

 */

static inline void blk_mq_tag_set_rq(struct blk_mq_hw_ctx *hctx,

		unsigned int tag, struct request *rq)

{

	hctx->tags->rqs[tag] = rq;

}



static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags,

					  unsigned int tag)

{

block/blk-mq.c

+16 −36
Original line number Diff line number Diff line
@@ -277,20 +277,26 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data, 
{

	struct blk_mq_tags *tags = blk_mq_tags_from_data(data);

	struct request *rq = tags->static_rqs[tag];

	req_flags_t rq_flags = 0;



	if (data->q->elevator) {

		rq->tag = BLK_MQ_NO_TAG;

		rq->internal_tag = tag;

	} else {

		if (data->hctx->flags & BLK_MQ_F_TAG_SHARED) {

			rq_flags = RQF_MQ_INFLIGHT;

			atomic_inc(&data->hctx->nr_active);

		}

		rq->tag = tag;

		rq->internal_tag = BLK_MQ_NO_TAG;

		data->hctx->tags->rqs[rq->tag] = rq;

	}



	/* csd/requeue_work/fifo_time is initialized before use */

	rq->q = data->q;

	rq->mq_ctx = data->ctx;

	rq->mq_hctx = data->hctx;

	rq->rq_flags = 0;

	rq->rq_flags = rq_flags;

	rq->cmd_flags = data->cmd_flags;

	if (data->flags & BLK_MQ_REQ_PREEMPT)

		rq->rq_flags |= RQF_PREEMPT;
@@ -660,32 +666,10 @@ static inline bool blk_mq_complete_need_ipi(struct request *rq) 
	return cpu_online(rq->mq_ctx->cpu);

}



static void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,

		struct request *rq)

{

	blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag);

	rq->tag = BLK_MQ_NO_TAG;



	if (rq->rq_flags & RQF_MQ_INFLIGHT) {

		rq->rq_flags &= ~RQF_MQ_INFLIGHT;

		atomic_dec(&hctx->nr_active);

	}

}



static inline void blk_mq_put_driver_tag(struct request *rq)

{

	if (rq->tag == BLK_MQ_NO_TAG || rq->internal_tag == BLK_MQ_NO_TAG)

		return;



	__blk_mq_put_driver_tag(rq->mq_hctx, rq);

}



bool blk_mq_complete_request_remote(struct request *rq)

{

	WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);



	blk_mq_put_driver_tag(rq);



	/*

	 * For a polled request, always complete locallly, it's pointless

	 * to redirect the completion.
@@ -1121,10 +1105,9 @@ static bool __blk_mq_get_driver_tag(struct request *rq) 
{

	struct sbitmap_queue *bt = &rq->mq_hctx->tags->bitmap_tags;

	unsigned int tag_offset = rq->mq_hctx->tags->nr_reserved_tags;

	bool shared = blk_mq_tag_busy(rq->mq_hctx);

	int tag;



	blk_mq_tag_busy(rq->mq_hctx);



	if (blk_mq_tag_is_reserved(rq->mq_hctx->sched_tags, rq->internal_tag)) {

		bt = &rq->mq_hctx->tags->breserved_tags;

		tag_offset = 0;
@@ -1137,22 +1120,19 @@ static bool __blk_mq_get_driver_tag(struct request *rq) 
		return false;



	rq->tag = tag + tag_offset;

	if (shared) {

		rq->rq_flags |= RQF_MQ_INFLIGHT;

		atomic_inc(&rq->mq_hctx->nr_active);

	}

	rq->mq_hctx->tags->rqs[rq->tag] = rq;

	return true;

}



static bool blk_mq_get_driver_tag(struct request *rq)

{

	struct blk_mq_hw_ctx *hctx = rq->mq_hctx;



	if (rq->tag == BLK_MQ_NO_TAG && !__blk_mq_get_driver_tag(rq))

		return false;



	if (hctx->flags & BLK_MQ_F_TAG_SHARED) {

		rq->rq_flags |= RQF_MQ_INFLIGHT;

		atomic_inc(&hctx->nr_active);

	}

	hctx->tags->rqs[rq->tag] = rq;

	if (rq->tag != BLK_MQ_NO_TAG)

		return true;

	return __blk_mq_get_driver_tag(rq);

}



static int blk_mq_dispatch_wake(wait_queue_entry_t *wait, unsigned mode,

block/blk-mq.h

+20 −0
Original line number Diff line number Diff line
@@ -193,6 +193,26 @@ static inline bool blk_mq_get_dispatch_budget(struct request_queue *q) 
	return true;

}



static inline void __blk_mq_put_driver_tag(struct blk_mq_hw_ctx *hctx,

					   struct request *rq)

{

	blk_mq_put_tag(hctx->tags, rq->mq_ctx, rq->tag);

	rq->tag = BLK_MQ_NO_TAG;



	if (rq->rq_flags & RQF_MQ_INFLIGHT) {

		rq->rq_flags &= ~RQF_MQ_INFLIGHT;

		atomic_dec(&hctx->nr_active);

	}

}



static inline void blk_mq_put_driver_tag(struct request *rq)

{

	if (rq->tag == BLK_MQ_NO_TAG || rq->internal_tag == BLK_MQ_NO_TAG)

		return;



	__blk_mq_put_driver_tag(rq->mq_hctx, rq);

}



static inline void blk_mq_clear_mq_map(struct blk_mq_queue_map *qmap)

{

	int cpu;

block/blk.h

+5 −0
Original line number Diff line number Diff line
@@ -25,6 +25,11 @@ struct blk_flush_queue { 
	struct list_head	flush_data_in_flight;

	struct request		*flush_rq;



	/*

	 * flush_rq shares tag with this rq, both can't be active

	 * at the same time

	 */

	struct request		*orig_rq;

	struct lock_class_key	key;

	spinlock_t		mq_flush_lock;

};

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