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Commit 11659569 authored by Bob Liu's avatar Bob Liu Committed by Konrad Rzeszutek Wilk
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xen/blkfront: split per device io_lock 



After patch "xen/blkfront: separate per ring information out of device
info", per-ring data is protected by a per-device lock ('io_lock').

This is not a good way and will effect the scalability, so introduce a
per-ring lock ('ring_lock').

The old 'io_lock' is renamed to 'dev_lock' which protects the ->grants list and
->persistent_gnts_c which are shared by all rings.

Note that in 'blkfront_probe' the 'blkfront_info' is setup via kzalloc
so setting ->persistent_gnts_c to zero is not needed.

Signed-off-by: default avatarBob Liu <bob.liu@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 3df0e505

drivers/block/xen-blkfront.c

+47 −26
Original line number Diff line number Diff line
@@ -125,6 +125,8 @@ MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the 
 *  depending on how many hardware queues/rings to be used.

 */

struct blkfront_ring_info {

	/* Lock to protect data in every ring buffer. */

	spinlock_t ring_lock;

	struct blkif_front_ring ring;

	unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];

	unsigned int evtchn, irq;
@@ -143,7 +145,6 @@ struct blkfront_ring_info { 
 */

struct blkfront_info

{

	spinlock_t io_lock;

	struct mutex mutex;

	struct xenbus_device *xbdev;

	struct gendisk *gd;
@@ -153,6 +154,11 @@ struct blkfront_info 
	/* Number of pages per ring buffer. */

	unsigned int nr_ring_pages;

	struct request_queue *rq;

	/*

	 * Lock to protect info->grants list and persistent_gnts_c shared by all

	 * rings.

	 */

	spinlock_t dev_lock;

	struct list_head grants;

	unsigned int persistent_gnts_c;

	unsigned int feature_flush;
@@ -258,7 +264,9 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 
		}



		gnt_list_entry->gref = GRANT_INVALID_REF;

		spin_lock_irq(&info->dev_lock);

		list_add(&gnt_list_entry->node, &info->grants);

		spin_unlock_irq(&info->dev_lock);

		i++;

	}
@@ -267,7 +275,9 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 
out_of_memory:

	list_for_each_entry_safe(gnt_list_entry, n,

	                         &info->grants, node) {

		spin_lock_irq(&info->dev_lock);

		list_del(&gnt_list_entry->node);

		spin_unlock_irq(&info->dev_lock);

		if (info->feature_persistent)

			__free_page(gnt_list_entry->page);

		kfree(gnt_list_entry);
@@ -280,7 +290,9 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 
static struct grant *get_free_grant(struct blkfront_info *info)

{

	struct grant *gnt_list_entry;

	unsigned long flags;



	spin_lock_irqsave(&info->dev_lock, flags);

	BUG_ON(list_empty(&info->grants));

	gnt_list_entry = list_first_entry(&info->grants, struct grant,

					  node);
@@ -288,6 +300,7 @@ static struct grant *get_free_grant(struct blkfront_info *info) 


	if (gnt_list_entry->gref != GRANT_INVALID_REF)

		info->persistent_gnts_c--;

	spin_unlock_irqrestore(&info->dev_lock, flags);



	return gnt_list_entry;

}
@@ -757,11 +770,11 @@ static inline bool blkif_request_flush_invalid(struct request *req, 
static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,

			   const struct blk_mq_queue_data *qd)

{

	unsigned long flags;

	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)hctx->driver_data;

	struct blkfront_info *info = rinfo->dev_info;



	blk_mq_start_request(qd->rq);

	spin_lock_irq(&info->io_lock);

	spin_lock_irqsave(&rinfo->ring_lock, flags);

	if (RING_FULL(&rinfo->ring))

		goto out_busy;
@@ -772,15 +785,15 @@ static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 
		goto out_busy;



	flush_requests(rinfo);

	spin_unlock_irq(&info->io_lock);

	spin_unlock_irqrestore(&rinfo->ring_lock, flags);

	return BLK_MQ_RQ_QUEUE_OK;



out_err:

	spin_unlock_irq(&info->io_lock);

	spin_unlock_irqrestore(&rinfo->ring_lock, flags);

	return BLK_MQ_RQ_QUEUE_ERROR;



out_busy:

	spin_unlock_irq(&info->io_lock);

	spin_unlock_irqrestore(&rinfo->ring_lock, flags);

	blk_mq_stop_hw_queue(hctx);

	return BLK_MQ_RQ_QUEUE_BUSY;

}
@@ -1082,21 +1095,28 @@ static void xlvbd_release_gendisk(struct blkfront_info *info) 
	info->gd = NULL;

}



/* Must be called with io_lock holded */

static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)

/* Already hold rinfo->ring_lock. */

static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)

{

	if (!RING_FULL(&rinfo->ring))

		blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);

}



static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)

{

	unsigned long flags;



	spin_lock_irqsave(&rinfo->ring_lock, flags);

	kick_pending_request_queues_locked(rinfo);

	spin_unlock_irqrestore(&rinfo->ring_lock, flags);

}



static void blkif_restart_queue(struct work_struct *work)

{

	struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);



	spin_lock_irq(&rinfo->dev_info->io_lock);

	if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)

		kick_pending_request_queues(rinfo);

	spin_unlock_irq(&rinfo->dev_info->io_lock);

}



static void blkif_free_ring(struct blkfront_ring_info *rinfo)
@@ -1188,7 +1208,6 @@ static void blkif_free(struct blkfront_info *info, int suspend) 
	unsigned int i;



	/* Prevent new requests being issued until we fix things up. */

	spin_lock_irq(&info->io_lock);

	info->connected = suspend ?

		BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;

	/* No more blkif_request(). */
@@ -1196,6 +1215,7 @@ static void blkif_free(struct blkfront_info *info, int suspend) 
		blk_mq_stop_hw_queues(info->rq);



	/* Remove all persistent grants */

	spin_lock_irq(&info->dev_lock);

	if (!list_empty(&info->grants)) {

		list_for_each_entry_safe(persistent_gnt, n,

					 &info->grants, node) {
@@ -1211,6 +1231,7 @@ static void blkif_free(struct blkfront_info *info, int suspend) 
		}

	}

	BUG_ON(info->persistent_gnts_c != 0);

	spin_unlock_irq(&info->dev_lock);



	for (i = 0; i < info->nr_rings; i++)

		blkif_free_ring(&info->rinfo[i]);
@@ -1218,7 +1239,6 @@ static void blkif_free(struct blkfront_info *info, int suspend) 
	kfree(info->rinfo);

	info->rinfo = NULL;

	info->nr_rings = 0;

	spin_unlock_irq(&info->io_lock);

}



struct copy_from_grant {
@@ -1253,6 +1273,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri 
	int i = 0;

	struct scatterlist *sg;

	int num_sg, num_grant;

	unsigned long flags;

	struct blkfront_info *info = rinfo->dev_info;

	struct copy_from_grant data = {

		.s = s,
@@ -1291,8 +1312,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri 
			if (!info->feature_persistent)

				pr_alert_ratelimited("backed has not unmapped grant: %u\n",

						     s->grants_used[i]->gref);

			spin_lock_irqsave(&info->dev_lock, flags);

			list_add(&s->grants_used[i]->node, &info->grants);

			info->persistent_gnts_c++;

			spin_unlock_irqrestore(&info->dev_lock, flags);

		} else {

			/*

			 * If the grant is not mapped by the backend we end the
@@ -1302,7 +1325,9 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri 
			 */

			gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);

			s->grants_used[i]->gref = GRANT_INVALID_REF;

			spin_lock_irqsave(&info->dev_lock, flags);

			list_add_tail(&s->grants_used[i]->node, &info->grants);

			spin_unlock_irqrestore(&info->dev_lock, flags);

		}

	}

	if (s->req.operation == BLKIF_OP_INDIRECT) {
@@ -1311,8 +1336,10 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri 
				if (!info->feature_persistent)

					pr_alert_ratelimited("backed has not unmapped grant: %u\n",

							     s->indirect_grants[i]->gref);

				spin_lock_irqsave(&info->dev_lock, flags);

				list_add(&s->indirect_grants[i]->node, &info->grants);

				info->persistent_gnts_c++;

				spin_unlock_irqrestore(&info->dev_lock, flags);

			} else {

				struct page *indirect_page;
@@ -1326,7 +1353,9 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *ri 
					list_add(&indirect_page->lru, &rinfo->indirect_pages);

				}

				s->indirect_grants[i]->gref = GRANT_INVALID_REF;

				spin_lock_irqsave(&info->dev_lock, flags);

				list_add_tail(&s->indirect_grants[i]->node, &info->grants);

				spin_unlock_irqrestore(&info->dev_lock, flags);

			}

		}

	}
@@ -1342,13 +1371,10 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) 
	struct blkfront_info *info = rinfo->dev_info;

	int error;



	spin_lock_irqsave(&info->io_lock, flags);



	if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {

		spin_unlock_irqrestore(&info->io_lock, flags);

	if (unlikely(info->connected != BLKIF_STATE_CONNECTED))

		return IRQ_HANDLED;

	}



	spin_lock_irqsave(&rinfo->ring_lock, flags);

 again:

	rp = rinfo->ring.sring->rsp_prod;

	rmb(); /* Ensure we see queued responses up to 'rp'. */
@@ -1439,9 +1465,9 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id) 
	} else

		rinfo->ring.sring->rsp_event = i + 1;



	kick_pending_request_queues(rinfo);

	kick_pending_request_queues_locked(rinfo);



	spin_unlock_irqrestore(&info->io_lock, flags);

	spin_unlock_irqrestore(&rinfo->ring_lock, flags);



	return IRQ_HANDLED;

}
@@ -1690,14 +1716,14 @@ static int blkfront_probe(struct xenbus_device *dev, 
		INIT_LIST_HEAD(&rinfo->indirect_pages);

		rinfo->dev_info = info;

		INIT_WORK(&rinfo->work, blkif_restart_queue);

		spin_lock_init(&rinfo->ring_lock);

	}



	mutex_init(&info->mutex);

	spin_lock_init(&info->io_lock);

	spin_lock_init(&info->dev_lock);

	info->xbdev = dev;

	info->vdevice = vdevice;

	INIT_LIST_HEAD(&info->grants);

	info->persistent_gnts_c = 0;

	info->connected = BLKIF_STATE_DISCONNECTED;



	/* Front end dir is a number, which is used as the id. */
@@ -1790,8 +1816,6 @@ static int blkif_recover(struct blkfront_info *info) 
	}

	xenbus_switch_state(info->xbdev, XenbusStateConnected);



	spin_lock_irq(&info->io_lock);



	/* Now safe for us to use the shared ring */

	info->connected = BLKIF_STATE_CONNECTED;
@@ -1809,7 +1833,6 @@ static int blkif_recover(struct blkfront_info *info) 
		BUG_ON(req->nr_phys_segments > segs);

		blk_mq_requeue_request(req);

	}

	spin_unlock_irq(&info->io_lock);

	blk_mq_kick_requeue_list(info->rq);



	while ((bio = bio_list_pop(&bio_list)) != NULL) {
@@ -2158,11 +2181,9 @@ static void blkfront_connect(struct blkfront_info *info) 
	xenbus_switch_state(info->xbdev, XenbusStateConnected);



	/* Kick pending requests. */

	spin_lock_irq(&info->io_lock);

	info->connected = BLKIF_STATE_CONNECTED;

	for (i = 0; i < info->nr_rings; i++)

		kick_pending_request_queues(&info->rinfo[i]);

	spin_unlock_irq(&info->io_lock);



	add_disk(info->gd);