block: restructure get_request() (b679281a) · Commits · 戴 / test

block/blk-core.c

+29 −31

Original line number	Diff line number	Diff line
		@@ -826,7 +826,7 @@ static bool blk_rq_should_init_elevator(struct bio *bio)
		static struct request get_request(struct request_queue q, int rw_flags,
		struct bio *bio, gfp_t gfp_mask)
		{
		struct request *rq = NULL;
		struct request *rq;
		struct request_list *rl = &q->rq;
		struct elevator_type *et;
		struct io_context *ioc;
		@@ -878,7 +878,7 @@ retry:
		* process is not a "batcher", and not
		* exempted by the IO scheduler
		*/
		goto out;
		return NULL;
		}
		}
		}
		@@ -891,7 +891,7 @@ retry:
		* allocated with any setting of ->nr_requests
		*/
		if (rl->count[is_sync] >= (3 * q->nr_requests / 2))
		goto out;
		return NULL;

		rl->count[is_sync]++;
		rl->starved[is_sync] = 0;
		@@ -921,49 +921,47 @@ retry:
		if ((rw_flags & REQ_ELVPRIV) && unlikely(et->icq_cache && !icq)) {
		icq = ioc_create_icq(q, gfp_mask);
		if (!icq)
		goto fail_icq;
		goto fail_alloc;
		}

		rq = blk_alloc_request(q, icq, rw_flags, gfp_mask);
		if (unlikely(!rq))
		goto fail_alloc;

		/*
		* ioc may be NULL here, and ioc_batching will be false. That's
		* OK, if the queue is under the request limit then requests need
		* not count toward the nr_batch_requests limit. There will always
		* be some limit enforced by BLK_BATCH_TIME.
		*/
		if (ioc_batching(q, ioc))
		ioc->nr_batch_requests--;

		trace_block_getrq(q, bio, rw_flags & 1);
		return rq;

		fail_icq:
		if (unlikely(!rq)) {
		fail_alloc:
		/*
		* Allocation failed presumably due to memory. Undo anything
		* we might have messed up.
		* Allocation failed presumably due to memory. Undo anything we
		* might have messed up.
		*
		* Allocating task should really be put onto the front of the
		* wait queue, but this is pretty rare.
		* Allocating task should really be put onto the front of the wait
		* queue, but this is pretty rare.
		*/
		spin_lock_irq(q->queue_lock);
		freed_request(q, rw_flags);

		/*
		* in the very unlikely event that allocation failed and no
		* requests for this direction was pending, mark us starved
		* so that freeing of a request in the other direction will
		* notice us. another possible fix would be to split the
		* rq mempool into READ and WRITE
		* requests for this direction was pending, mark us starved so that
		* freeing of a request in the other direction will notice
		* us. another possible fix would be to split the rq mempool into
		* READ and WRITE
		*/
		rq_starved:
		if (unlikely(rl->count[is_sync] == 0))
		rl->starved[is_sync] = 1;

		goto out;
		}

		/*
		* ioc may be NULL here, and ioc_batching will be false. That's
		* OK, if the queue is under the request limit then requests need
		* not count toward the nr_batch_requests limit. There will always
		* be some limit enforced by BLK_BATCH_TIME.
		*/
		if (ioc_batching(q, ioc))
		ioc->nr_batch_requests--;

		trace_block_getrq(q, bio, rw_flags & 1);
		out:
		return rq;
		return NULL;
		}

		/**

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