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Commit cb96a42c authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
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blk-mq: fix schedule from atomic context 



blk_mq_put_ctx() has to be called before io_schedule() in
bt_get().

This patch fixes the problem by taking similar approach from
percpu_ida allocation for the situation.

Signed-off-by: default avatarMing Lei <tom.leiming@gmail.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 1aecfe48

block/blk-mq-tag.c

+31 −17
Original line number Diff line number Diff line
@@ -221,8 +221,10 @@ static struct bt_wait_state *bt_wait_ptr(struct blk_mq_bitmap_tags *bt, 
	return bs;

}



static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx,

		  unsigned int *last_tag, gfp_t gfp)

static int bt_get(struct blk_mq_alloc_data *data,

		struct blk_mq_bitmap_tags *bt,

		struct blk_mq_hw_ctx *hctx,

		unsigned int *last_tag)

{

	struct bt_wait_state *bs;

	DEFINE_WAIT(wait);
@@ -232,7 +234,7 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx, 
	if (tag != -1)

		return tag;



	if (!(gfp & __GFP_WAIT))

	if (!(data->gfp & __GFP_WAIT))

		return -1;



	bs = bt_wait_ptr(bt, hctx);
@@ -249,50 +251,62 @@ static int bt_get(struct blk_mq_bitmap_tags *bt, struct blk_mq_hw_ctx *hctx, 
		if (was_empty)

			atomic_set(&bs->wait_cnt, bt->wake_cnt);



		blk_mq_put_ctx(data->ctx);



		io_schedule();



		data->ctx = blk_mq_get_ctx(data->q);

		data->hctx = data->q->mq_ops->map_queue(data->q,

				data->ctx->cpu);

		if (data->reserved) {

			bt = &data->hctx->tags->breserved_tags;

		} else {

			last_tag = &data->ctx->last_tag;

			hctx = data->hctx;

			bt = &hctx->tags->bitmap_tags;

		}

		finish_wait(&bs->wait, &wait);

		bs = bt_wait_ptr(bt, hctx);

	} while (1);



	finish_wait(&bs->wait, &wait);

	return tag;

}



static unsigned int __blk_mq_get_tag(struct blk_mq_tags *tags,

				     struct blk_mq_hw_ctx *hctx,

				     unsigned int *last_tag, gfp_t gfp)

static unsigned int __blk_mq_get_tag(struct blk_mq_alloc_data *data)

{

	int tag;



	tag = bt_get(&tags->bitmap_tags, hctx, last_tag, gfp);

	tag = bt_get(data, &data->hctx->tags->bitmap_tags, data->hctx,

			&data->ctx->last_tag);

	if (tag >= 0)

		return tag + tags->nr_reserved_tags;

		return tag + data->hctx->tags->nr_reserved_tags;



	return BLK_MQ_TAG_FAIL;

}



static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_tags *tags,

					      gfp_t gfp)

static unsigned int __blk_mq_get_reserved_tag(struct blk_mq_alloc_data *data)

{

	int tag, zero = 0;



	if (unlikely(!tags->nr_reserved_tags)) {

	if (unlikely(!data->hctx->tags->nr_reserved_tags)) {

		WARN_ON_ONCE(1);

		return BLK_MQ_TAG_FAIL;

	}



	tag = bt_get(&tags->breserved_tags, NULL, &zero, gfp);

	tag = bt_get(data, &data->hctx->tags->breserved_tags, NULL, &zero);

	if (tag < 0)

		return BLK_MQ_TAG_FAIL;



	return tag;

}



unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag,

			    gfp_t gfp, bool reserved)

unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data)

{

	if (!reserved)

		return __blk_mq_get_tag(hctx->tags, hctx, last_tag, gfp);

	if (!data->reserved)

		return __blk_mq_get_tag(data);



	return __blk_mq_get_reserved_tag(hctx->tags, gfp);

	return __blk_mq_get_reserved_tag(data);

}



static struct bt_wait_state *bt_wake_ptr(struct blk_mq_bitmap_tags *bt)

block/blk-mq-tag.h

+1 −1
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ struct blk_mq_tags { 
extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node);

extern void blk_mq_free_tags(struct blk_mq_tags *tags);



extern unsigned int blk_mq_get_tag(struct blk_mq_hw_ctx *hctx, unsigned int *last_tag, gfp_t gfp, bool reserved);

extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data);

extern void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, unsigned int tag, unsigned int *last_tag);

extern bool blk_mq_has_free_tags(struct blk_mq_tags *tags);

extern ssize_t blk_mq_tag_sysfs_show(struct blk_mq_tags *tags, char *page);

block/blk-mq.c

+23 −13
Original line number Diff line number Diff line
@@ -210,24 +210,23 @@ static void blk_mq_rq_ctx_init(struct request_queue *q, struct blk_mq_ctx *ctx, 
}



static struct request *

__blk_mq_alloc_request(struct request_queue *q, struct blk_mq_hw_ctx *hctx,

		struct blk_mq_ctx *ctx, int rw, gfp_t gfp, bool reserved)

__blk_mq_alloc_request(struct blk_mq_alloc_data *data, int rw)

{

	struct request *rq;

	unsigned int tag;



	tag = blk_mq_get_tag(hctx, &ctx->last_tag, gfp, reserved);

	tag = blk_mq_get_tag(data);

	if (tag != BLK_MQ_TAG_FAIL) {

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

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



		rq->cmd_flags = 0;

		if (blk_mq_tag_busy(hctx)) {

		if (blk_mq_tag_busy(data->hctx)) {

			rq->cmd_flags = REQ_MQ_INFLIGHT;

			atomic_inc(&hctx->nr_active);

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

		}



		rq->tag = tag;

		blk_mq_rq_ctx_init(q, ctx, rq, rw);

		blk_mq_rq_ctx_init(data->q, data->ctx, rq, rw);

		return rq;

	}
@@ -240,22 +239,27 @@ struct request *blk_mq_alloc_request(struct request_queue *q, int rw, gfp_t gfp, 
	struct blk_mq_ctx *ctx;

	struct blk_mq_hw_ctx *hctx;

	struct request *rq;

	struct blk_mq_alloc_data alloc_data;



	if (blk_mq_queue_enter(q))

		return NULL;



	ctx = blk_mq_get_ctx(q);

	hctx = q->mq_ops->map_queue(q, ctx->cpu);

	blk_mq_set_alloc_data(&alloc_data, q, gfp & ~__GFP_WAIT,

			reserved, ctx, hctx);



	rq = __blk_mq_alloc_request(q, hctx, ctx, rw, gfp & ~__GFP_WAIT,

				    reserved);

	rq = __blk_mq_alloc_request(&alloc_data, rw);

	if (!rq && (gfp & __GFP_WAIT)) {

		__blk_mq_run_hw_queue(hctx);

		blk_mq_put_ctx(ctx);



		ctx = blk_mq_get_ctx(q);

		hctx = q->mq_ops->map_queue(q, ctx->cpu);

		rq =  __blk_mq_alloc_request(q, hctx, ctx, rw, gfp, reserved);

		blk_mq_set_alloc_data(&alloc_data, q, gfp, reserved, ctx,

				hctx);

		rq =  __blk_mq_alloc_request(&alloc_data, rw);

		ctx = alloc_data.ctx;

	}

	blk_mq_put_ctx(ctx);

	return rq;
@@ -1136,6 +1140,7 @@ static struct request *blk_mq_map_request(struct request_queue *q, 
	struct blk_mq_ctx *ctx;

	struct request *rq;

	int rw = bio_data_dir(bio);

	struct blk_mq_alloc_data alloc_data;



	if (unlikely(blk_mq_queue_enter(q))) {

		bio_endio(bio, -EIO);
@@ -1149,7 +1154,9 @@ static struct request *blk_mq_map_request(struct request_queue *q, 
		rw |= REQ_SYNC;



	trace_block_getrq(q, bio, rw);

	rq = __blk_mq_alloc_request(q, hctx, ctx, rw, GFP_ATOMIC, false);

	blk_mq_set_alloc_data(&alloc_data, q, GFP_ATOMIC, false, ctx,

			hctx);

	rq = __blk_mq_alloc_request(&alloc_data, rw);

	if (unlikely(!rq)) {

		__blk_mq_run_hw_queue(hctx);

		blk_mq_put_ctx(ctx);
@@ -1157,8 +1164,11 @@ static struct request *blk_mq_map_request(struct request_queue *q, 


		ctx = blk_mq_get_ctx(q);

		hctx = q->mq_ops->map_queue(q, ctx->cpu);

		rq = __blk_mq_alloc_request(q, hctx, ctx, rw,

					    __GFP_WAIT|GFP_ATOMIC, false);

		blk_mq_set_alloc_data(&alloc_data, q,

				__GFP_WAIT|GFP_ATOMIC, false, ctx, hctx);

		rq = __blk_mq_alloc_request(&alloc_data, rw);

		ctx = alloc_data.ctx;

		hctx = alloc_data.hctx;

	}



	hctx->queued++;

block/blk-mq.h

+23 −0
Original line number Diff line number Diff line
@@ -91,4 +91,27 @@ static inline void blk_mq_put_ctx(struct blk_mq_ctx *ctx) 
	put_cpu();

}



struct blk_mq_alloc_data {

	/* input parameter */

	struct request_queue *q;

	gfp_t gfp;

	bool reserved;



	/* input & output parameter */

	struct blk_mq_ctx *ctx;

	struct blk_mq_hw_ctx *hctx;

};



static inline void blk_mq_set_alloc_data(struct blk_mq_alloc_data *data,

		struct request_queue *q, gfp_t gfp, bool reserved,

		struct blk_mq_ctx *ctx,

		struct blk_mq_hw_ctx *hctx)

{

	data->q = q;

	data->gfp = gfp;

	data->reserved = reserved;

	data->ctx = ctx;

	data->hctx = hctx;

}



#endif