1 files changed, 59 insertions, 29 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7552ca8f8ffe..f5dfc1694679 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -244,34 +244,77 @@ out_of_memory:
 	return -ENOMEM;
 }
 
-static struct grant *get_grant(grant_ref_t *gref_head,
-			       struct page *page,
-			       struct blkfront_info *info)
+static struct grant *get_free_grant(struct blkfront_info *info)
 {
 	struct grant *gnt_list_entry;
-	unsigned long buffer_gfn;
 
 	BUG_ON(list_empty(&info->grants));
 	gnt_list_entry = list_first_entry(&info->grants, struct grant,
-	                                  node);
+					  node);
 	list_del(&gnt_list_entry->node);
 
-	if (gnt_list_entry->gref != GRANT_INVALID_REF) {
+	if (gnt_list_entry->gref != GRANT_INVALID_REF)
 		info->persistent_gnts_c--;
+
+	return gnt_list_entry;
+}
+
+static inline void grant_foreign_access(const struct grant *gnt_list_entry,
+					const struct blkfront_info *info)
+{
+	gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
+						 info->xbdev->otherend_id,
+						 gnt_list_entry->page,
+						 0);
+}
+
+static struct grant *get_grant(grant_ref_t *gref_head,
+			       unsigned long gfn,
+			       struct blkfront_info *info)
+{
+	struct grant *gnt_list_entry = get_free_grant(info);
+
+	if (gnt_list_entry->gref != GRANT_INVALID_REF)
 		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)
+		grant_foreign_access(gnt_list_entry, info);
+	else {
+		/* Grant access to the GFN passed by the caller */
+		gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
+						info->xbdev->otherend_id,
+						gfn, 0);
 	}
 
+	return gnt_list_entry;
+}
+
+static struct grant *get_indirect_grant(grant_ref_t *gref_head,
+					struct blkfront_info *info)
+{
+	struct grant *gnt_list_entry = get_free_grant(info);
+
+	if (gnt_list_entry->gref != GRANT_INVALID_REF)
+		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) {
-		BUG_ON(!page);
-		gnt_list_entry->page = page;
+		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,
+						 struct page, lru);
+		list_del(&indirect_page->lru);
+		gnt_list_entry->page = indirect_page;
 	}
-	buffer_gfn = xen_page_to_gfn(gnt_list_entry->page);
-	gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
-	                                info->xbdev->otherend_id,
-	                                buffer_gfn, 0);
+	grant_foreign_access(gnt_list_entry, info);
+
 	return gnt_list_entry;
 }
 
@@ -524,32 +567,19 @@ static int blkif_queue_rw_req(struct request *req)
 
 		if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 		    (i % SEGS_PER_INDIRECT_FRAME == 0)) {
-			struct page *uninitialized_var(page);
-
 			if (segments)
 				kunmap_atomic(segments);
 
 			n = i / SEGS_PER_INDIRECT_FRAME;
-			if (!info->feature_persistent) {
-				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,
-								 struct page, lru);
-				list_del(&indirect_page->lru);
-				page = indirect_page;
-			}
-			gnt_list_entry = get_grant(&gref_head, page, info);
+			gnt_list_entry = get_indirect_grant(&gref_head, info);
 			info->shadow[id].indirect_grants[n] = gnt_list_entry;
 			segments = kmap_atomic(gnt_list_entry->page);
 			ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 		}
 
-		gnt_list_entry = get_grant(&gref_head, sg_page(sg), info);
+		gnt_list_entry = get_grant(&gref_head,
+					   xen_page_to_gfn(sg_page(sg)),
+					   info);
 		ref = gnt_list_entry->gref;
 
 		info->shadow[id].grants_used[i] = gnt_list_entry;