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Commit 3df0e505 authored by Bob Liu's avatar Bob Liu Committed by Konrad Rzeszutek Wilk
Browse files

xen/blkfront: pseudo support for multi hardware queues/rings 



Preparatory patch for multiple hardware queues (rings). The number of
rings is unconditionally set to 1, larger number will be enabled in
patch "xen/blkfront: negotiate number of queues/rings to be used with backend"
so as to make review easier.

Note that blkfront_gather_backend_features does not call
blkfront_setup_indirect anymore (as that needs to be done per ring).
That means that in blkif_recover/blkif_connect we have to do it in a loop
(bounded by nr_rings).

Signed-off-by: default avatarBob Liu <bob.liu@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 81f35161

drivers/block/xen-blkfront.c

+198 −145
Original line number Diff line number Diff line
@@ -150,6 +150,7 @@ struct blkfront_info 
	int vdevice;

	blkif_vdev_t handle;

	enum blkif_state connected;

	/* Number of pages per ring buffer. */

	unsigned int nr_ring_pages;

	struct request_queue *rq;

	struct list_head grants;
@@ -164,7 +165,8 @@ struct blkfront_info 
	unsigned int max_indirect_segments;

	int is_ready;

	struct blk_mq_tag_set tag_set;

	struct blkfront_ring_info rinfo;

	struct blkfront_ring_info *rinfo;

	unsigned int nr_rings;

};



static unsigned int nr_minors;
@@ -209,7 +211,7 @@ static DEFINE_SPINLOCK(minor_lock); 
#define GREFS(_psegs)	((_psegs) * GRANTS_PER_PSEG)



static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);

static int blkfront_gather_backend_features(struct blkfront_info *info);

static void blkfront_gather_backend_features(struct blkfront_info *info);



static int get_id_from_freelist(struct blkfront_ring_info *rinfo)

{
@@ -338,8 +340,8 @@ static struct grant *get_indirect_grant(grant_ref_t *gref_head, 
		struct page *indirect_page;



		/* Fetch a pre-allocated page to use for indirect grefs */

		BUG_ON(list_empty(&info->rinfo.indirect_pages));

		indirect_page = list_first_entry(&info->rinfo.indirect_pages,

		BUG_ON(list_empty(&info->rinfo->indirect_pages));

		indirect_page = list_first_entry(&info->rinfo->indirect_pages,

						 struct page, lru);

		list_del(&indirect_page->lru);

		gnt_list_entry->page = indirect_page;
@@ -597,7 +599,6 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri 
	 * existing persistent grants, or if we have to get new grants,

	 * as there are not sufficiently many free.

	 */

	bool new_persistent_gnts;

	struct scatterlist *sg;

	int num_sg, max_grefs, num_grant;
@@ -609,12 +610,12 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri 
		 */

		max_grefs += INDIRECT_GREFS(max_grefs);



	/* Check if we have enough grants to allocate a requests */

	if (info->persistent_gnts_c < max_grefs) {

		new_persistent_gnts = 1;

		if (gnttab_alloc_grant_references(

		    max_grefs - info->persistent_gnts_c,

		    &setup.gref_head) < 0) {

	/*

	 * We have to reserve 'max_grefs' grants because persistent

	 * grants are shared by all rings.

	 */

	if (max_grefs > 0)

		if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {

			gnttab_request_free_callback(

				&rinfo->callback,

				blkif_restart_queue_callback,
@@ -622,8 +623,6 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri 
				max_grefs);

			return 1;

		}

	} else

		new_persistent_gnts = 0;



	/* Fill out a communications ring structure. */

	ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
@@ -712,7 +711,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri 
	/* Keep a private copy so we can reissue requests when recovering. */

	rinfo->shadow[id].req = *ring_req;



	if (new_persistent_gnts)

	if (max_grefs > 0)

		gnttab_free_grant_references(setup.gref_head);



	return 0;
@@ -791,7 +790,8 @@ static int blk_mq_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, 
{

	struct blkfront_info *info = (struct blkfront_info *)data;



	hctx->driver_data = &info->rinfo;

	BUG_ON(info->nr_rings <= index);

	hctx->driver_data = &info->rinfo[index];

	return 0;

}
@@ -1050,8 +1050,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 


static void xlvbd_release_gendisk(struct blkfront_info *info)

{

	unsigned int minor, nr_minors;

	struct blkfront_ring_info *rinfo = &info->rinfo;

	unsigned int minor, nr_minors, i;



	if (info->rq == NULL)

		return;
@@ -1059,11 +1058,15 @@ static void xlvbd_release_gendisk(struct blkfront_info *info) 
	/* No more blkif_request(). */

	blk_mq_stop_hw_queues(info->rq);



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

		struct blkfront_ring_info *rinfo = &info->rinfo[i];



		/* No more gnttab callback work. */

		gnttab_cancel_free_callback(&rinfo->callback);



		/* Flush gnttab callback work. Must be done with no locks held. */

		flush_work(&rinfo->work);

	}



	del_gendisk(info->gd);
@@ -1096,37 +1099,11 @@ static void blkif_restart_queue(struct work_struct *work) 
	spin_unlock_irq(&rinfo->dev_info->io_lock);

}



static void blkif_free(struct blkfront_info *info, int suspend)

static void blkif_free_ring(struct blkfront_ring_info *rinfo)

{

	struct grant *persistent_gnt;

	struct grant *n;

	struct blkfront_info *info = rinfo->dev_info;

	int i, j, segs;

	struct blkfront_ring_info *rinfo = &info->rinfo;



	/* 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(). */

	if (info->rq)

		blk_mq_stop_hw_queues(info->rq);



	/* Remove all persistent grants */

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

		list_for_each_entry_safe(persistent_gnt, n,

					 &info->grants, node) {

			list_del(&persistent_gnt->node);

			if (persistent_gnt->gref != GRANT_INVALID_REF) {

				gnttab_end_foreign_access(persistent_gnt->gref,

				                          0, 0UL);

				info->persistent_gnts_c--;

			}

			if (info->feature_persistent)

				__free_page(persistent_gnt->page);

			kfree(persistent_gnt);

		}

	}

	BUG_ON(info->persistent_gnts_c != 0);



	/*

	 * Remove indirect pages, this only happens when using indirect
@@ -1186,7 +1163,6 @@ static void blkif_free(struct blkfront_info *info, int suspend) 


	/* No more gnttab callback work. */

	gnttab_cancel_free_callback(&rinfo->callback);

	spin_unlock_irq(&info->io_lock);



	/* Flush gnttab callback work. Must be done with no locks held. */

	flush_work(&rinfo->work);
@@ -1204,7 +1180,45 @@ static void blkif_free(struct blkfront_info *info, int suspend) 
	if (rinfo->irq)

		unbind_from_irqhandler(rinfo->irq, rinfo);

	rinfo->evtchn = rinfo->irq = 0;

}



static void blkif_free(struct blkfront_info *info, int suspend)

{

	struct grant *persistent_gnt, *n;

	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(). */

	if (info->rq)

		blk_mq_stop_hw_queues(info->rq);



	/* Remove all persistent grants */

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

		list_for_each_entry_safe(persistent_gnt, n,

					 &info->grants, node) {

			list_del(&persistent_gnt->node);

			if (persistent_gnt->gref != GRANT_INVALID_REF) {

				gnttab_end_foreign_access(persistent_gnt->gref,

							  0, 0UL);

				info->persistent_gnts_c--;

			}

			if (info->feature_persistent)

				__free_page(persistent_gnt->page);

			kfree(persistent_gnt);

		}

	}

	BUG_ON(info->persistent_gnts_c != 0);



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

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



	kfree(info->rinfo);

	info->rinfo = NULL;

	info->nr_rings = 0;

	spin_unlock_irq(&info->io_lock);

}



struct copy_from_grant {
@@ -1492,7 +1506,7 @@ static int talk_to_blkback(struct xenbus_device *dev, 
	int err, i;

	unsigned int max_page_order = 0;

	unsigned int ring_page_order = 0;

	struct blkfront_ring_info *rinfo = &info->rinfo;

	struct blkfront_ring_info *rinfo;



	err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,

			   "max-ring-page-order", "%u", &max_page_order);
@@ -1503,10 +1517,13 @@ static int talk_to_blkback(struct xenbus_device *dev, 
		info->nr_ring_pages = 1 << ring_page_order;

	}



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

		rinfo = &info->rinfo[i];

		/* Create shared ring, alloc event channel. */

		err = setup_blkring(dev, rinfo);

		if (err)

		goto out;

			goto destroy_blkring;

	}



again:

	err = xenbus_transaction_start(&xbt);
@@ -1515,6 +1532,8 @@ static int talk_to_blkback(struct xenbus_device *dev, 
		goto destroy_blkring;

	}



	if (info->nr_rings == 1) {

		rinfo = &info->rinfo[0];

		if (info->nr_ring_pages == 1) {

			err = xenbus_printf(xbt, dev->nodename,

					    "ring-ref", "%u", rinfo->ring_ref[0]);
@@ -1548,6 +1567,10 @@ static int talk_to_blkback(struct xenbus_device *dev, 
			message = "writing event-channel";

			goto abort_transaction;

		}

	} else {

		/* Not supported at this stage. */

		goto abort_transaction;

	}

	err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",

			    XEN_IO_PROTO_ABI_NATIVE);

	if (err) {
@@ -1568,9 +1591,15 @@ static int talk_to_blkback(struct xenbus_device *dev, 
		goto destroy_blkring;

	}



	for (i = 0; i < BLK_RING_SIZE(info); i++)

		rinfo->shadow[i].req.u.rw.id = i+1;

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

		unsigned int j;



		rinfo = &info->rinfo[i];



		for (j = 0; j < BLK_RING_SIZE(info); j++)

			rinfo->shadow[j].req.u.rw.id = j + 1;

		rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;

	}

	xenbus_switch_state(dev, XenbusStateInitialised);



	return 0;
@@ -1581,7 +1610,7 @@ static int talk_to_blkback(struct xenbus_device *dev, 
		xenbus_dev_fatal(dev, err, "%s", message);

 destroy_blkring:

	blkif_free(info, 0);

 out:



	return err;

}
@@ -1595,8 +1624,8 @@ static int blkfront_probe(struct xenbus_device *dev, 
			  const struct xenbus_device_id *id)

{

	int err, vdevice;

	unsigned int r_index;

	struct blkfront_info *info;

	struct blkfront_ring_info *rinfo;



	/* FIXME: Use dynamic device id if this is not set. */

	err = xenbus_scanf(XBT_NIL, dev->nodename,
@@ -1646,10 +1675,22 @@ static int blkfront_probe(struct xenbus_device *dev, 
		return -ENOMEM;

	}



	rinfo = &info->rinfo;

	info->nr_rings = 1;

	info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);

	if (!info->rinfo) {

		xenbus_dev_fatal(dev, -ENOMEM, "allocating ring_info structure");

		kfree(info);

		return -ENOMEM;

	}



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

		struct blkfront_ring_info *rinfo;



		rinfo = &info->rinfo[r_index];

		INIT_LIST_HEAD(&rinfo->indirect_pages);

		rinfo->dev_info = info;

		INIT_WORK(&rinfo->work, blkif_restart_queue);

	}



	mutex_init(&info->mutex);

	spin_lock_init(&info->io_lock);
@@ -1681,7 +1722,7 @@ static void split_bio_end(struct bio *bio) 


static int blkif_recover(struct blkfront_info *info)

{

	int i;

	unsigned int i, r_index;

	struct request *req, *n;

	struct blk_shadow *copy;

	int rc;
@@ -1691,8 +1732,17 @@ static int blkif_recover(struct blkfront_info *info) 
	int pending, size;

	struct split_bio *split_bio;

	struct list_head requests;

	struct blkfront_ring_info *rinfo = &info->rinfo;



	blkfront_gather_backend_features(info);

	segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;

	blk_queue_max_segments(info->rq, segs);

	bio_list_init(&bio_list);

	INIT_LIST_HEAD(&requests);



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

		struct blkfront_ring_info *rinfo;



		rinfo = &info->rinfo[r_index];

		/* Stage 1: Make a safe copy of the shadow state. */

		copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),

			       GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
@@ -1706,16 +1756,12 @@ static int blkif_recover(struct blkfront_info *info) 
		rinfo->shadow_free = rinfo->ring.req_prod_pvt;

		rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;



	rc = blkfront_gather_backend_features(info);

		rc = blkfront_setup_indirect(rinfo);

		if (rc) {

			kfree(copy);

			return rc;

		}



	segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;

	blk_queue_max_segments(info->rq, segs);

	bio_list_init(&bio_list);

	INIT_LIST_HEAD(&requests);

		for (i = 0; i < BLK_RING_SIZE(info); i++) {

			/* Not in use? */

			if (!copy[i].request)
@@ -1741,7 +1787,7 @@ static int blkif_recover(struct blkfront_info *info) 
		}



		kfree(copy);



	}

	xenbus_switch_state(info->xbdev, XenbusStateConnected);



	spin_lock_irq(&info->io_lock);
@@ -1749,8 +1795,13 @@ static int blkif_recover(struct blkfront_info *info) 
	/* Now safe for us to use the shared ring */

	info->connected = BLKIF_STATE_CONNECTED;



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

		struct blkfront_ring_info *rinfo;



		rinfo = &info->rinfo[r_index];

		/* Kick any other new requests queued since we resumed */

		kick_pending_request_queues(rinfo);

	}



	list_for_each_entry_safe(req, n, &requests, queuelist) {

		/* Requeue pending requests (flush or discard) */
@@ -1961,7 +2012,7 @@ static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 
/*

 * Gather all backend feature-*

 */

static int blkfront_gather_backend_features(struct blkfront_info *info)

static void blkfront_gather_backend_features(struct blkfront_info *info)

{

	int err;

	int barrier, flush, discard, persistent;
@@ -2016,8 +2067,6 @@ static int blkfront_gather_backend_features(struct blkfront_info *info) 
	else

		info->max_indirect_segments = min(indirect_segments,

						  xen_blkif_max_segments);



	return blkfront_setup_indirect(&info->rinfo);

}



/*
@@ -2030,8 +2079,7 @@ static void blkfront_connect(struct blkfront_info *info) 
	unsigned long sector_size;

	unsigned int physical_sector_size;

	unsigned int binfo;

	int err;

	struct blkfront_ring_info *rinfo = &info->rinfo;

	int err, i;



	switch (info->connected) {

	case BLKIF_STATE_CONNECTED:
@@ -2088,11 +2136,15 @@ static void blkfront_connect(struct blkfront_info *info) 
	if (err != 1)

		physical_sector_size = sector_size;



	err = blkfront_gather_backend_features(info);

	blkfront_gather_backend_features(info);

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

		err = blkfront_setup_indirect(&info->rinfo[i]);

		if (err) {

			xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",

					 info->xbdev->otherend);

		return;

			blkif_free(info, 0);

			break;

		}

	}



	err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
@@ -2108,7 +2160,8 @@ static void blkfront_connect(struct blkfront_info *info) 
	/* Kick pending requests. */

	spin_lock_irq(&info->io_lock);

	info->connected = BLKIF_STATE_CONNECTED;

	kick_pending_request_queues(rinfo);

	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);