1 files changed, 18 insertions, 6 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index bd2b3bbbb22c..48e98f2712b5 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -329,8 +329,18 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
         struct gnttab_unmap_grant_ref unmap[BLKIF_MAX_SEGMENTS_PER_REQUEST];
         struct page *pages[BLKIF_MAX_SEGMENTS_PER_REQUEST];
         struct persistent_gnt *persistent_gnt;
-        int ret, segs_to_unmap = 0;
+        int segs_to_unmap = 0;
         struct xen_blkif *blkif = container_of(work, typeof(*blkif), persistent_purge_work);
+        struct gntab_unmap_queue_data unmap_data;
+        struct completion unmap_completion;
+
+        init_completion(&unmap_completion);
+
+        unmap_data.data = &unmap_completion;
+        unmap_data.done = &free_persistent_gnts_unmap_callback;
+        unmap_data.pages = pages;
+        unmap_data.unmap_ops = unmap;
+        unmap_data.kunmap_ops = NULL;
 
         while(!list_empty(&blkif->persistent_purge_list)) {
                 persistent_gnt = list_first_entry(&blkif->persistent_purge_list,
@@ -346,17 +356,19 @@ void xen_blkbk_unmap_purged_grants(struct work_struct *work)
                 pages[segs_to_unmap] = persistent_gnt->page;
 
                 if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
-                        ret = gnttab_unmap_refs(unmap, NULL, pages,
-                                segs_to_unmap);
-                        BUG_ON(ret);
+                        unmap_data.count = segs_to_unmap;
+                        gnttab_unmap_refs_async(&unmap_data);
+                        wait_for_completion(&unmap_completion);
+
                         put_free_pages(blkif, pages, segs_to_unmap);
                         segs_to_unmap = 0;
                 }
                 kfree(persistent_gnt);
         }
         if (segs_to_unmap > 0) {
-                ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
-                BUG_ON(ret);
+                unmap_data.count = segs_to_unmap;
+                gnttab_unmap_refs_async(&unmap_data);
+                wait_for_completion(&unmap_completion);
                 put_free_pages(blkif, pages, segs_to_unmap);
         }
 }