xen/blkback: remove per-queue plugging (0faa8cca) · Commits · 戴 / test

drivers/xen/blkback/blkback.c

+9 −35

Original line number	Diff line number	Diff line
		@@ -166,38 +166,6 @@ static void free_req(struct pending_req *req)
		wake_up(&blkbk->pending_free_wq);
		}

		/*
		* Give back a reference count on the underlaying storage.
		* It is OK to make multiple calls in this function as it
		* resets the plug to NULL when it is done on the first call.
		*/
		static void unplug_queue(struct blkif_st *blkif)
		{
		if (blkif->plug == NULL)
		return;
		if (blkif->plug->unplug_fn)
		blkif->plug->unplug_fn(blkif->plug);
		blk_put_queue(blkif->plug);
		blkif->plug = NULL;
		}

		/*
		* Take a reference count on the underlaying storage.
		* It is OK to call this multiple times as we check to make sure
		* not to double reference. We also give back a reference count
		* if it corresponds to another queue.
		*/
		static void plug_queue(struct blkif_st blkif, struct block_device bdev)
		{
		struct request_queue *q = bdev_get_queue(bdev);

		if (q == blkif->plug)
		return;
		unplug_queue(blkif);
		blk_get_queue(q);
		blkif->plug = q;
		}

		/*
		* Unmap the grant references, and also remove the M2P over-rides
		* used in the 'pending_req'.
		@@ -280,7 +248,6 @@ int blkif_schedule(void *arg)

		if (do_block_io_op(blkif))
		blkif->waiting_reqs = 1;
		unplug_queue(blkif);

		if (log_stats && time_after(jiffies, blkif->st_print))
		print_stats(blkif);
		@@ -456,6 +423,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
		struct bio *bio = NULL;
		int ret, i;
		int operation;
		struct blk_plug plug;
		struct request_queue *q;

		switch (req->operation) {
		case BLKIF_OP_READ:
		@@ -561,7 +530,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
		}

		/* Get a reference count for the disk queue and start sending I/O */
		plug_queue(blkif, preq.bdev);
		blk_get_queue(q);
		blk_start_plug(&plug);

		/* We set it one so that the last submit_bio does not have to call
		* atomic_inc.
		@@ -620,11 +590,14 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
		else if (operation == WRITE \|\| operation == WRITE_BARRIER)
		blkif->st_wr_sect += preq.nr_sects;

		blk_finish_plug(&plug);
		blk_put_queue(q);
		return;

		fail_flush:
		fast_flush_area(pending_req);
		fail_response:
		/* Haven't submitted any bio's yet. */
		make_response(blkif, req->id, req->operation, BLKIF_RSP_ERROR);
		free_req(pending_req);
		msleep(1); /* back off a bit */
		@@ -634,7 +607,8 @@ static void dispatch_rw_block_io(struct blkif_st *blkif,
		__end_block_io_op(pending_req, -EINVAL);
		if (bio)
		bio_put(bio);
		unplug_queue(blkif);
		blk_finish_plug(&plug);
		blk_put_queue(q);
		msleep(1); /* back off a bit */
		return;
		}

drivers/xen/blkback/common.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -79,7 +79,6 @@ struct blkif_st {
		/* One thread per one blkif. */
		struct task_struct *xenblkd;
		unsigned int waiting_reqs;
		struct request_queue *plug;

		/* statistics */
		unsigned long st_print;

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