[PATCH 04/10] xen/blkfront: separate ring information to an new struct

[Bob Liu <bob.liu@oracle.com>]

A ring is the representation of a hardware queue, this patch separate ring
information from blkfront_info to an new struct blkfront_ring_info to make
preparation for real multi hardware queues supporting.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Bob Liu <bob.liu@oracle.com>
---
 drivers/block/xen-blkfront.c | 403 +++++++++++++++++++++++--------------------
 1 file changed, 218 insertions(+), 185 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 5a90a51..aaa4a0e 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -102,23 +102,15 @@ MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default
 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
 
 /*
- * We have one of these per vbd, whether ide, scsi or 'other'.  They
- * hang in private_data off the gendisk structure. We may end up
- * putting all kinds of interesting stuff here :-)
+ *  Per-ring info.
+ *  A blkfront_info structure can associate with one or more blkfront_ring_info,
+ *  depending on how many hardware queues supported.
  */
-struct blkfront_info
-{
+struct blkfront_ring_info {
 	spinlock_t io_lock;
-	struct mutex mutex;
-	struct xenbus_device *xbdev;
-	struct gendisk *gd;
-	int vdevice;
-	blkif_vdev_t handle;
-	enum blkif_state connected;
 	int ring_ref;
 	struct blkif_front_ring ring;
 	unsigned int evtchn, irq;
-	struct request_queue *rq;
 	struct work_struct work;
 	struct gnttab_free_callback callback;
 	struct blk_shadow shadow[BLK_RING_SIZE];
@@ -126,6 +118,22 @@ struct blkfront_info
 	struct list_head indirect_pages;
 	unsigned int persistent_gnts_c;
 	unsigned long shadow_free;
+	struct blkfront_info *info;
+};
+
+/*
+ * We have one of these per vbd, whether ide, scsi or 'other'.  They
+ * hang in private_data off the gendisk structure. We may end up
+ * putting all kinds of interesting stuff here :-)
+ */
+struct blkfront_info {
+	struct mutex mutex;
+	struct xenbus_device *xbdev;
+	struct gendisk *gd;
+	int vdevice;
+	blkif_vdev_t handle;
+	enum blkif_state connected;
+	struct request_queue *rq;
 	unsigned int feature_flush;
 	unsigned int feature_discard:1;
 	unsigned int feature_secdiscard:1;
@@ -135,6 +143,7 @@ struct blkfront_info
 	unsigned int max_indirect_segments;
 	int is_ready;
 	struct blk_mq_tag_set tag_set;
+	struct blkfront_ring_info rinfo;
 };
 
 static unsigned int nr_minors;
@@ -167,34 +176,35 @@ static DEFINE_SPINLOCK(minor_lock);
 #define INDIRECT_GREFS(_segs) \
 	((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 
-static int blkfront_setup_indirect(struct blkfront_info *info);
+static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 
-static int get_id_from_freelist(struct blkfront_info *info)
+static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 {
-	unsigned long free = info->shadow_free;
+	unsigned long free = rinfo->shadow_free;
 	BUG_ON(free >= BLK_RING_SIZE);
-	info->shadow_free = info->shadow[free].req.u.rw.id;
-	info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
+	rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
+	rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 	return free;
 }
 
-static int add_id_to_freelist(struct blkfront_info *info,
+static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 			       unsigned long id)
 {
-	if (info->shadow[id].req.u.rw.id != id)
+	if (rinfo->shadow[id].req.u.rw.id != id)
 		return -EINVAL;
-	if (info->shadow[id].request == NULL)
+	if (rinfo->shadow[id].request == NULL)
 		return -EINVAL;
-	info->shadow[id].req.u.rw.id  = info->shadow_free;
-	info->shadow[id].request = NULL;
-	info->shadow_free = id;
+	rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
+	rinfo->shadow[id].request = NULL;
+	rinfo->shadow_free = id;
 	return 0;
 }
 
-static int fill_grant_buffer(struct blkfront_info *info, int num)
+static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 {
 	struct page *granted_page;
 	struct grant *gnt_list_entry, *n;
+	struct blkfront_info *info = rinfo->info;
 	int i = 0;
 
 	while(i < num) {
@@ -212,7 +222,7 @@ static int fill_grant_buffer(struct blkfront_info *info, int num)
 		}
 
 		gnt_list_entry->gref = GRANT_INVALID_REF;
-		list_add(&gnt_list_entry->node, &info->grants);
+		list_add(&gnt_list_entry->node, &rinfo->grants);
 		i++;
 	}
 
@@ -220,7 +230,7 @@ static int fill_grant_buffer(struct blkfront_info *info, int num)
 
 out_of_memory:
 	list_for_each_entry_safe(gnt_list_entry, n,
-	                         &info->grants, node) {
+			&rinfo->grants, node) {
 		list_del(&gnt_list_entry->node);
 		if (info->feature_persistent)
 			__free_page(pfn_to_page(gnt_list_entry->pfn));
@@ -232,33 +242,33 @@ out_of_memory:
 }
 
 static struct grant *get_grant(grant_ref_t *gref_head,
-                               unsigned long pfn,
-                               struct blkfront_info *info)
+		unsigned long pfn,
+		struct blkfront_ring_info *rinfo)
 {
 	struct grant *gnt_list_entry;
 	unsigned long buffer_mfn;
 
-	BUG_ON(list_empty(&info->grants));
-	gnt_list_entry = list_first_entry(&info->grants, struct grant,
+	BUG_ON(list_empty(&rinfo->grants));
+	gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 	                                  node);
 	list_del(&gnt_list_entry->node);
 
 	if (gnt_list_entry->gref != GRANT_INVALID_REF) {
-		info->persistent_gnts_c--;
+		rinfo->persistent_gnts_c--;
 		return gnt_list_entry;
 	}
 
 	/* Assign a gref to this page */
 	gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 	BUG_ON(gnt_list_entry->gref == -ENOSPC);
-	if (!info->feature_persistent) {
+	if (!rinfo->info->feature_persistent) {
 		BUG_ON(!pfn);
 		gnt_list_entry->pfn = pfn;
 	}
 	buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
 	gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
-	                                info->xbdev->otherend_id,
-	                                buffer_mfn, 0);
+			rinfo->info->xbdev->otherend_id,
+			buffer_mfn, 0);
 	return gnt_list_entry;
 }
 
@@ -328,8 +338,9 @@ static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 
 static void blkif_restart_queue_callback(void *arg)
 {
-	struct blkfront_info *info = (struct blkfront_info *)arg;
-	schedule_work(&info->work);
+	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
+
+	schedule_work(&rinfo->work);
 }
 
 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
@@ -387,7 +398,8 @@ static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
  *
  * @req: a request struct
  */
-static int blkif_queue_request(struct request *req)
+static int blkif_queue_request(struct request *req,
+		struct blkfront_ring_info *rinfo)
 {
 	struct blkfront_info *info = req->rq_disk->private_data;
 	struct blkif_request *ring_req;
@@ -419,15 +431,15 @@ static int blkif_queue_request(struct request *req)
 		max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
 
 	/* Check if we have enough grants to allocate a requests */
-	if (info->persistent_gnts_c < max_grefs) {
+	if (rinfo->persistent_gnts_c < max_grefs) {
 		new_persistent_gnts = 1;
 		if (gnttab_alloc_grant_references(
-		    max_grefs - info->persistent_gnts_c,
+		    max_grefs - rinfo->persistent_gnts_c,
 		    &gref_head) < 0) {
 			gnttab_request_free_callback(
-				&info->callback,
+				&rinfo->callback,
 				blkif_restart_queue_callback,
-				info,
+				rinfo,
 				max_grefs);
 			return 1;
 		}
@@ -435,9 +447,9 @@ static int blkif_queue_request(struct request *req)
 		new_persistent_gnts = 0;
 
 	/* Fill out a communications ring structure. */
-	ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
-	id = get_id_from_freelist(info);
-	info->shadow[id].request = req;
+	ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
+	id = get_id_from_freelist(rinfo);
+	rinfo->shadow[id].request = req;
 
 	if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
 		ring_req->operation = BLKIF_OP_DISCARD;
@@ -453,7 +465,7 @@ static int blkif_queue_request(struct request *req)
 		       req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
 		BUG_ON(info->max_indirect_segments &&
 		       req->nr_phys_segments > info->max_indirect_segments);
-		nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
+		nseg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 		ring_req->u.rw.id = id;
 		if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
 			/*
@@ -496,7 +508,7 @@ static int blkif_queue_request(struct request *req)
 			}
 			ring_req->u.rw.nr_segments = nseg;
 		}
-		for_each_sg(info->shadow[id].sg, sg, nseg, i) {
+		for_each_sg(rinfo->shadow[id].sg, sg, nseg, i) {
 			fsect = sg->offset >> 9;
 			lsect = fsect + (sg->length >> 9) - 1;
 
@@ -512,22 +524,22 @@ static int blkif_queue_request(struct request *req)
 					struct page *indirect_page;
 
 					/* Fetch a pre-allocated page to use for indirect grefs */
-					BUG_ON(list_empty(&info->indirect_pages));
-					indirect_page = list_first_entry(&info->indirect_pages,
+					BUG_ON(list_empty(&rinfo->indirect_pages));
+					indirect_page = list_first_entry(&rinfo->indirect_pages,
 					                                 struct page, lru);
 					list_del(&indirect_page->lru);
 					pfn = page_to_pfn(indirect_page);
 				}
-				gnt_list_entry = get_grant(&gref_head, pfn, info);
-				info->shadow[id].indirect_grants[n] = gnt_list_entry;
+				gnt_list_entry = get_grant(&gref_head, pfn, rinfo);
+				rinfo->shadow[id].indirect_grants[n] = gnt_list_entry;
 				segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
 				ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 			}
 
-			gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
+			gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), rinfo);
 			ref = gnt_list_entry->gref;
 
-			info->shadow[id].grants_used[i] = gnt_list_entry;
+			rinfo->shadow[id].grants_used[i] = gnt_list_entry;
 
 			if (rq_data_dir(req) && info->feature_persistent) {
 				char *bvec_data;
@@ -573,10 +585,10 @@ static int blkif_queue_request(struct request *req)
 			kunmap_atomic(segments);
 	}
 
-	info->ring.req_prod_pvt++;
+	rinfo->ring.req_prod_pvt++;
 
 	/* Keep a private copy so we can reissue requests when recovering. */
-	info->shadow[id].req = *ring_req;
+	rinfo->shadow[id].req = *ring_req;
 
 	if (new_persistent_gnts)
 		gnttab_free_grant_references(gref_head);
@@ -585,14 +597,14 @@ static int blkif_queue_request(struct request *req)
 }
 
 
-static inline void flush_requests(struct blkfront_info *info)
+static inline void flush_requests(struct blkfront_ring_info *rinfo)
 {
 	int notify;
 
-	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
+	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 
 	if (notify)
-		notify_remote_via_irq(info->irq);
+		notify_remote_via_irq(rinfo->irq);
 }
 
 static inline bool blkif_request_flush_invalid(struct request *req,
@@ -608,40 +620,50 @@ static inline bool blkif_request_flush_invalid(struct request *req,
 static int blk_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 			const struct blk_mq_queue_data *qd)
 {
-	struct blkfront_info *info = qd->rq->rq_disk->private_data;
+	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)hctx->driver_data;
 	int ret = BLK_MQ_RQ_QUEUE_OK;
 
 	blk_mq_start_request(qd->rq);
-	spin_lock_irq(&info->io_lock);
-	if (RING_FULL(&info->ring)) {
-		spin_unlock_irq(&info->io_lock);
+	spin_lock_irq(&rinfo->io_lock);
+	if (RING_FULL(&rinfo->ring)) {
+		spin_unlock_irq(&rinfo->io_lock);
 		blk_mq_stop_hw_queue(hctx);
 		ret = BLK_MQ_RQ_QUEUE_BUSY;
 		goto out;
 	}
 
-	if (blkif_request_flush_invalid(qd->rq, info)) {
-		spin_unlock_irq(&info->io_lock);
+	if (blkif_request_flush_invalid(qd->rq, rinfo->info)) {
+		spin_unlock_irq(&rinfo->io_lock);
 		ret = BLK_MQ_RQ_QUEUE_ERROR;
 		goto out;
 	}
 
-	if (blkif_queue_request(qd->rq)) {
-		spin_unlock_irq(&info->io_lock);
+	if (blkif_queue_request(qd->rq, rinfo)) {
+		spin_unlock_irq(&rinfo->io_lock);
 		blk_mq_stop_hw_queue(hctx);
 		ret = BLK_MQ_RQ_QUEUE_BUSY;
 		goto out;
 	}
 
-	flush_requests(info);
-	spin_unlock_irq(&info->io_lock);
+	flush_requests(rinfo);
+	spin_unlock_irq(&rinfo->io_lock);
 out:
 	return ret;
 }
 
+static int blk_mq_init_hctx(struct blk_mq_hw_ctx *hctx, void *data,
+		unsigned int index)
+{
+	struct blkfront_info *info = (struct blkfront_info *)data;
+
+	hctx->driver_data = &info->rinfo;
+	return 0;
+}
+
 static struct blk_mq_ops blkfront_mq_ops = {
 	.queue_rq = blk_mq_queue_rq,
 	.map_queue = blk_mq_map_queue,
+	.init_hctx = blk_mq_init_hctx,
 };
 
 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
@@ -894,6 +916,7 @@ 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;
 
 	if (info->rq == NULL)
 		return;
@@ -902,10 +925,10 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	blk_mq_stop_hw_queues(info->rq);
 
 	/* No more gnttab callback work. */
-	gnttab_cancel_free_callback(&info->callback);
+	gnttab_cancel_free_callback(&rinfo->callback);
 
 	/* Flush gnttab callback work. Must be done with no locks held. */
-	flush_work(&info->work);
+	flush_work(&rinfo->work);
 
 	del_gendisk(info->gd);
 
@@ -921,25 +944,25 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	info->gd = NULL;
 }
 
-static void kick_pending_request_queues(struct blkfront_info *info)
+static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&info->io_lock, flags);
-	if (!RING_FULL(&info->ring)) {
-		spin_unlock_irqrestore(&info->io_lock, flags);
-		blk_mq_start_stopped_hw_queues(info->rq, true);
+	spin_lock_irqsave(&rinfo->io_lock, flags);
+	if (!RING_FULL(&rinfo->ring)) {
+		spin_unlock_irqrestore(&rinfo->io_lock, flags);
+		blk_mq_start_stopped_hw_queues(rinfo->info->rq, true);
 		return;
 	}
-	spin_unlock_irqrestore(&info->io_lock, flags);
+	spin_unlock_irqrestore(&rinfo->io_lock, flags);
 }
 
 static void blkif_restart_queue(struct work_struct *work)
 {
-	struct blkfront_info *info = container_of(work, struct blkfront_info, work);
+	struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
 
-	if (info->connected == BLKIF_STATE_CONNECTED)
-		kick_pending_request_queues(info);
+	if (rinfo->info->connected == BLKIF_STATE_CONNECTED)
+		kick_pending_request_queues(rinfo);
 }
 
 static void blkif_free(struct blkfront_info *info, int suspend)
@@ -947,6 +970,7 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 	struct grant *persistent_gnt;
 	struct grant *n;
 	int i, j, segs;
+	struct blkfront_ring_info *rinfo = &info->rinfo;
 
 	/* Prevent new requests being issued until we fix things up. */
 	info->connected = suspend ?
@@ -955,33 +979,33 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 	if (info->rq)
 		blk_mq_stop_hw_queues(info->rq);
 
-	spin_lock_irq(&info->io_lock);
+	spin_lock_irq(&rinfo->io_lock);
 	/* Remove all persistent grants */
-	if (!list_empty(&info->grants)) {
+	if (!list_empty(&rinfo->grants)) {
 		list_for_each_entry_safe(persistent_gnt, n,
-		                         &info->grants, node) {
+				&rinfo->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--;
+						0, 0UL);
+				rinfo->persistent_gnts_c--;
 			}
 			if (info->feature_persistent)
 				__free_page(pfn_to_page(persistent_gnt->pfn));
 			kfree(persistent_gnt);
 		}
 	}
-	BUG_ON(info->persistent_gnts_c != 0);
+	BUG_ON(rinfo->persistent_gnts_c != 0);
 
 	/*
 	 * Remove indirect pages, this only happens when using indirect
 	 * descriptors but not persistent grants
 	 */
-	if (!list_empty(&info->indirect_pages)) {
+	if (!list_empty(&rinfo->indirect_pages)) {
 		struct page *indirect_page, *n;
 
 		BUG_ON(info->feature_persistent);
-		list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
+		list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
 			list_del(&indirect_page->lru);
 			__free_page(indirect_page);
 		}
@@ -992,21 +1016,21 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 		 * Clear persistent grants present in requests already
 		 * on the shared ring
 		 */
-		if (!info->shadow[i].request)
+		if (!rinfo->shadow[i].request)
 			goto free_shadow;
 
-		segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
-		       info->shadow[i].req.u.indirect.nr_segments :
-		       info->shadow[i].req.u.rw.nr_segments;
+		segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
+		       rinfo->shadow[i].req.u.indirect.nr_segments :
+		       rinfo->shadow[i].req.u.rw.nr_segments;
 		for (j = 0; j < segs; j++) {
-			persistent_gnt = info->shadow[i].grants_used[j];
+			persistent_gnt = rinfo->shadow[i].grants_used[j];
 			gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
 			if (info->feature_persistent)
 				__free_page(pfn_to_page(persistent_gnt->pfn));
 			kfree(persistent_gnt);
 		}
 
-		if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
+		if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
 			/*
 			 * If this is not an indirect operation don't try to
 			 * free indirect segments
@@ -1014,42 +1038,42 @@ static void blkif_free(struct blkfront_info *info, int suspend)
 			goto free_shadow;
 
 		for (j = 0; j < INDIRECT_GREFS(segs); j++) {
-			persistent_gnt = info->shadow[i].indirect_grants[j];
+			persistent_gnt = rinfo->shadow[i].indirect_grants[j];
 			gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
 			__free_page(pfn_to_page(persistent_gnt->pfn));
 			kfree(persistent_gnt);
 		}
 
 free_shadow:
-		kfree(info->shadow[i].grants_used);
-		info->shadow[i].grants_used = NULL;
-		kfree(info->shadow[i].indirect_grants);
-		info->shadow[i].indirect_grants = NULL;
-		kfree(info->shadow[i].sg);
-		info->shadow[i].sg = NULL;
+		kfree(rinfo->shadow[i].grants_used);
+		rinfo->shadow[i].grants_used = NULL;
+		kfree(rinfo->shadow[i].indirect_grants);
+		rinfo->shadow[i].indirect_grants = NULL;
+		kfree(rinfo->shadow[i].sg);
+		rinfo->shadow[i].sg = NULL;
 	}
 
 	/* No more gnttab callback work. */
-	gnttab_cancel_free_callback(&info->callback);
-	spin_unlock_irq(&info->io_lock);
+	gnttab_cancel_free_callback(&rinfo->callback);
+	spin_unlock_irq(&rinfo->io_lock);
 
 	/* Flush gnttab callback work. Must be done with no locks held. */
-	flush_work(&info->work);
+	flush_work(&rinfo->work);
 
 	/* Free resources associated with old device channel. */
-	if (info->ring_ref != GRANT_INVALID_REF) {
-		gnttab_end_foreign_access(info->ring_ref, 0,
-					  (unsigned long)info->ring.sring);
-		info->ring_ref = GRANT_INVALID_REF;
-		info->ring.sring = NULL;
+	if (rinfo->ring_ref != GRANT_INVALID_REF) {
+		gnttab_end_foreign_access(rinfo->ring_ref, 0,
+					  (unsigned long)rinfo->ring.sring);
+		rinfo->ring_ref = GRANT_INVALID_REF;
+		rinfo->ring.sring = NULL;
 	}
-	if (info->irq)
-		unbind_from_irqhandler(info->irq, info);
-	info->evtchn = info->irq = 0;
+	if (rinfo->irq)
+		unbind_from_irqhandler(rinfo->irq, rinfo);
+	rinfo->evtchn = rinfo->irq = 0;
 
 }
 
-static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
+static void blkif_completion(struct blk_shadow *s, struct blkfront_ring_info *rinfo,
 			     struct blkif_response *bret)
 {
 	int i = 0;
@@ -1057,6 +1081,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
 	char *bvec_data;
 	void *shared_data;
 	int nseg;
+	struct blkfront_info *info = rinfo->info;
 
 	nseg = s->req.operation == BLKIF_OP_INDIRECT ?
 		s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
@@ -1092,8 +1117,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
 			if (!info->feature_persistent)
 				pr_alert_ratelimited("backed has not unmapped grant: %u\n",
 						     s->grants_used[i]->gref);
-			list_add(&s->grants_used[i]->node, &info->grants);
-			info->persistent_gnts_c++;
+			list_add(&s->grants_used[i]->node, &rinfo->grants);
+			rinfo->persistent_gnts_c++;
 		} else {
 			/*
 			 * If the grant is not mapped by the backend we end the
@@ -1103,7 +1128,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
 			 */
 			gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
 			s->grants_used[i]->gref = GRANT_INVALID_REF;
-			list_add_tail(&s->grants_used[i]->node, &info->grants);
+			list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
 		}
 	}
 	if (s->req.operation == BLKIF_OP_INDIRECT) {
@@ -1112,8 +1137,8 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
 				if (!info->feature_persistent)
 					pr_alert_ratelimited("backed has not unmapped grant: %u\n",
 							     s->indirect_grants[i]->gref);
-				list_add(&s->indirect_grants[i]->node, &info->grants);
-				info->persistent_gnts_c++;
+				list_add(&s->indirect_grants[i]->node, &rinfo->grants);
+				rinfo->persistent_gnts_c++;
 			} else {
 				struct page *indirect_page;
 
@@ -1123,9 +1148,9 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
 				 * available pages for indirect grefs.
 				 */
 				indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
-				list_add(&indirect_page->lru, &info->indirect_pages);
+				list_add(&indirect_page->lru, &rinfo->indirect_pages);
 				s->indirect_grants[i]->gref = GRANT_INVALID_REF;
-				list_add_tail(&s->indirect_grants[i]->node, &info->grants);
+				list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
 			}
 		}
 	}
@@ -1137,20 +1162,21 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 	struct blkif_response *bret;
 	RING_IDX i, rp;
 	unsigned long flags;
-	struct blkfront_info *info = (struct blkfront_info *)dev_id;
+	struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
+	struct blkfront_info *info = rinfo->info;
 
 	if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 		return IRQ_HANDLED;
 
-	spin_lock_irqsave(&info->io_lock, flags);
+	spin_lock_irqsave(&rinfo->io_lock, flags);
  again:
-	rp = info->ring.sring->rsp_prod;
+	rp = rinfo->ring.sring->rsp_prod;
 	rmb(); /* Ensure we see queued responses up to 'rp'. */
 
-	for (i = info->ring.rsp_cons; i != rp; i++) {
+	for (i = rinfo->ring.rsp_cons; i != rp; i++) {
 		unsigned long id;
 
-		bret = RING_GET_RESPONSE(&info->ring, i);
+		bret = RING_GET_RESPONSE(&rinfo->ring, i);
 		id   = bret->id;
 		/*
 		 * The backend has messed up and given us an id that we would
@@ -1164,12 +1190,12 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 			 * the id is busted. */
 			continue;
 		}
-		req  = info->shadow[id].request;
+		req  = rinfo->shadow[id].request;
 
 		if (bret->operation != BLKIF_OP_DISCARD)
-			blkif_completion(&info->shadow[id], info, bret);
+			blkif_completion(&rinfo->shadow[id], rinfo, bret);
 
-		if (add_id_to_freelist(info, id)) {
+		if (add_id_to_freelist(rinfo, id)) {
 			WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
 			     info->gd->disk_name, op_name(bret->operation), id);
 			continue;
@@ -1198,7 +1224,7 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 				req->errors = -EOPNOTSUPP;
 			}
 			if (unlikely(bret->status == BLKIF_RSP_ERROR &&
-				     info->shadow[id].req.u.rw.nr_segments == 0)) {
+				     rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
 				printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
 				       info->gd->disk_name, op_name(bret->operation));
 				req->errors = -EOPNOTSUPP;
@@ -1223,30 +1249,30 @@ static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 		}
 	}
 
-	info->ring.rsp_cons = i;
+	rinfo->ring.rsp_cons = i;
 
-	if (i != info->ring.req_prod_pvt) {
+	if (i != rinfo->ring.req_prod_pvt) {
 		int more_to_do;
-		RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
+		RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
 		if (more_to_do)
 			goto again;
 	} else
-		info->ring.sring->rsp_event = i + 1;
+		rinfo->ring.sring->rsp_event = i + 1;
 
-	spin_unlock_irqrestore(&info->io_lock, flags);
-	kick_pending_request_queues(info);
+	spin_unlock_irqrestore(&rinfo->io_lock, flags);
+	kick_pending_request_queues(rinfo);
 
 	return IRQ_HANDLED;
 }
 
 
 static int setup_blkring(struct xenbus_device *dev,
-			 struct blkfront_info *info)
+			 struct blkfront_ring_info *rinfo)
 {
 	struct blkif_sring *sring;
 	int err;
 
-	info->ring_ref = GRANT_INVALID_REF;
+	rinfo->ring_ref = GRANT_INVALID_REF;
 
 	sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 	if (!sring) {
@@ -1254,32 +1280,32 @@ static int setup_blkring(struct xenbus_device *dev,
 		return -ENOMEM;
 	}
 	SHARED_RING_INIT(sring);
-	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
+	FRONT_RING_INIT(&rinfo->ring, sring, PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
+	err = xenbus_grant_ring(dev, virt_to_mfn(rinfo->ring.sring));
 	if (err < 0) {
 		free_page((unsigned long)sring);
-		info->ring.sring = NULL;
+		rinfo->ring.sring = NULL;
 		goto fail;
 	}
-	info->ring_ref = err;
+	rinfo->ring_ref = err;
 
-	err = xenbus_alloc_evtchn(dev, &info->evtchn);
+	err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
 	if (err)
 		goto fail;
 
-	err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
-					"blkif", info);
+	err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
+					"blkif", rinfo);
 	if (err <= 0) {
 		xenbus_dev_fatal(dev, err,
 				 "bind_evtchn_to_irqhandler failed");
 		goto fail;
 	}
-	info->irq = err;
+	rinfo->irq = err;
 
 	return 0;
 fail:
-	blkif_free(info, 0);
+	blkif_free(rinfo->info, 0);
 	return err;
 }
 
@@ -1291,9 +1317,10 @@ static int talk_to_blkback(struct xenbus_device *dev,
 	const char *message = NULL;
 	struct xenbus_transaction xbt;
 	int err;
+	struct blkfront_ring_info *rinfo = &info->rinfo;
 
 	/* Create shared ring, alloc event channel. */
-	err = setup_blkring(dev, info);
+	err = setup_blkring(dev, rinfo);
 	if (err)
 		goto out;
 
@@ -1305,13 +1332,13 @@ again:
 	}
 
 	err = xenbus_printf(xbt, dev->nodename,
-			    "ring-ref", "%u", info->ring_ref);
+			    "ring-ref", "%u", rinfo->ring_ref);
 	if (err) {
 		message = "writing ring-ref";
 		goto abort_transaction;
 	}
 	err = xenbus_printf(xbt, dev->nodename,
-			    "event-channel", "%u", info->evtchn);
+			    "event-channel", "%u", rinfo->evtchn);
 	if (err) {
 		message = "writing event-channel";
 		goto abort_transaction;
@@ -1361,6 +1388,7 @@ static int blkfront_probe(struct xenbus_device *dev,
 {
 	int err, vdevice, i;
 	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,
@@ -1410,19 +1438,21 @@ static int blkfront_probe(struct xenbus_device *dev,
 		return -ENOMEM;
 	}
 
+	rinfo = &info->rinfo;
 	mutex_init(&info->mutex);
-	spin_lock_init(&info->io_lock);
+	spin_lock_init(&rinfo->io_lock);
 	info->xbdev = dev;
 	info->vdevice = vdevice;
-	INIT_LIST_HEAD(&info->grants);
-	INIT_LIST_HEAD(&info->indirect_pages);
-	info->persistent_gnts_c = 0;
+	INIT_LIST_HEAD(&rinfo->grants);
+	INIT_LIST_HEAD(&rinfo->indirect_pages);
+	rinfo->persistent_gnts_c = 0;
 	info->connected = BLKIF_STATE_DISCONNECTED;
-	INIT_WORK(&info->work, blkif_restart_queue);
+	rinfo->info = info;
+	INIT_WORK(&rinfo->work, blkif_restart_queue);
 
 	for (i = 0; i < BLK_RING_SIZE; i++)
-		info->shadow[i].req.u.rw.id = i+1;
-	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
+		rinfo->shadow[i].req.u.rw.id = i+1;
+	rinfo->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
 
 	/* Front end dir is a number, which is used as the id. */
 	info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
@@ -1465,21 +1495,22 @@ 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;
 
 	/* Stage 1: Make a safe copy of the shadow state. */
-	copy = kmemdup(info->shadow, sizeof(info->shadow),
+	copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),
 		       GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
 	if (!copy)
 		return -ENOMEM;
 
 	/* Stage 2: Set up free list. */
-	memset(&info->shadow, 0, sizeof(info->shadow));
+	memset(&rinfo->shadow, 0, sizeof(rinfo->shadow));
 	for (i = 0; i < BLK_RING_SIZE; i++)
-		info->shadow[i].req.u.rw.id = i+1;
-	info->shadow_free = info->ring.req_prod_pvt;
-	info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
+		rinfo->shadow[i].req.u.rw.id = i+1;
+	rinfo->shadow_free = rinfo->ring.req_prod_pvt;
+	rinfo->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
 
-	rc = blkfront_setup_indirect(info);
+	rc = blkfront_setup_indirect(rinfo);
 	if (rc) {
 		kfree(copy);
 		return rc;
@@ -1521,7 +1552,7 @@ static int blkif_recover(struct blkfront_info *info)
 	info->connected = BLKIF_STATE_CONNECTED;
 
 	/* Kick any other new requests queued since we resumed */
-	kick_pending_request_queues(info);
+	kick_pending_request_queues(rinfo);
 
 	list_for_each_entry_safe(req, n, &requests, queuelist) {
 		/* Requeue pending requests (flush or discard) */
@@ -1654,10 +1685,11 @@ static void blkfront_setup_discard(struct blkfront_info *info)
 		info->feature_secdiscard = !!discard_secure;
 }
 
-static int blkfront_setup_indirect(struct blkfront_info *info)
+static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
 {
 	unsigned int indirect_segments, segs;
 	int err, i;
+	struct blkfront_info *info = rinfo->info;
 
 	err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 			    "feature-max-indirect-segments", "%u", &indirect_segments,
@@ -1671,7 +1703,7 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
 		segs = info->max_indirect_segments;
 	}
 
-	err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
+	err = fill_grant_buffer(rinfo, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
 	if (err)
 		goto out_of_memory;
 
@@ -1683,31 +1715,31 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
 		 */
 		int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE;
 
-		BUG_ON(!list_empty(&info->indirect_pages));
+		BUG_ON(!list_empty(&rinfo->indirect_pages));
 		for (i = 0; i < num; i++) {
 			struct page *indirect_page = alloc_page(GFP_NOIO);
 			if (!indirect_page)
 				goto out_of_memory;
-			list_add(&indirect_page->lru, &info->indirect_pages);
+			list_add(&indirect_page->lru, &rinfo->indirect_pages);
 		}
 	}
 
 	for (i = 0; i < BLK_RING_SIZE; i++) {
-		info->shadow[i].grants_used = kzalloc(
-			sizeof(info->shadow[i].grants_used[0]) * segs,
+		rinfo->shadow[i].grants_used = kzalloc(
+			sizeof(rinfo->shadow[i].grants_used[0]) * segs,
 			GFP_NOIO);
-		info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
+		rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * segs, GFP_NOIO);
 		if (info->max_indirect_segments)
-			info->shadow[i].indirect_grants = kzalloc(
-				sizeof(info->shadow[i].indirect_grants[0]) *
+			rinfo->shadow[i].indirect_grants = kzalloc(
+				sizeof(rinfo->shadow[i].indirect_grants[0]) *
 				INDIRECT_GREFS(segs),
 				GFP_NOIO);
-		if ((info->shadow[i].grants_used == NULL) ||
-			(info->shadow[i].sg == NULL) ||
+		if ((rinfo->shadow[i].grants_used == NULL) ||
+			(rinfo->shadow[i].sg == NULL) ||
 		     (info->max_indirect_segments &&
-		     (info->shadow[i].indirect_grants == NULL)))
+		     (rinfo->shadow[i].indirect_grants == NULL)))
 			goto out_of_memory;
-		sg_init_table(info->shadow[i].sg, segs);
+		sg_init_table(rinfo->shadow[i].sg, segs);
 	}
 
 
@@ -1715,16 +1747,16 @@ static int blkfront_setup_indirect(struct blkfront_info *info)
 
 out_of_memory:
 	for (i = 0; i < BLK_RING_SIZE; i++) {
-		kfree(info->shadow[i].grants_used);
-		info->shadow[i].grants_used = NULL;
-		kfree(info->shadow[i].sg);
-		info->shadow[i].sg = NULL;
-		kfree(info->shadow[i].indirect_grants);
-		info->shadow[i].indirect_grants = NULL;
-	}
-	if (!list_empty(&info->indirect_pages)) {
+		kfree(rinfo->shadow[i].grants_used);
+		rinfo->shadow[i].grants_used = NULL;
+		kfree(rinfo->shadow[i].sg);
+		rinfo->shadow[i].sg = NULL;
+		kfree(rinfo->shadow[i].indirect_grants);
+		rinfo->shadow[i].indirect_grants = NULL;
+	}
+	if (!list_empty(&rinfo->indirect_pages)) {
 		struct page *indirect_page, *n;
-		list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
+		list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
 			list_del(&indirect_page->lru);
 			__free_page(indirect_page);
 		}
@@ -1744,6 +1776,7 @@ static void blkfront_connect(struct blkfront_info *info)
 	unsigned int binfo;
 	int err;
 	int barrier, flush, discard, persistent;
+	struct blkfront_ring_info *rinfo = &info->rinfo;
 
 	switch (info->connected) {
 	case BLKIF_STATE_CONNECTED:
@@ -1841,7 +1874,7 @@ static void blkfront_connect(struct blkfront_info *info)
 	else
 		info->feature_persistent = persistent;
 
-	err = blkfront_setup_indirect(info);
+	err = blkfront_setup_indirect(rinfo);
 	if (err) {
 		xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
 				 info->xbdev->otherend);
@@ -1860,7 +1893,7 @@ static void blkfront_connect(struct blkfront_info *info)
 
 	/* Kick pending requests. */
 	info->connected = BLKIF_STATE_CONNECTED;
-	kick_pending_request_queues(info);
+	kick_pending_request_queues(rinfo);
 
 	add_disk(info->gd);
 
-- 
1.8.3.1