1 files changed, 8 insertions, 7 deletions

diff --git a/drivers/block/xen-blkback/blkback.c b/drivers/block/xen-blkback/blkback.c
index dba55e3a4a86..c73910cc28c9 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -175,8 +175,14 @@ static int xen_vbd_translate(struct phys_req *req, struct xen_blkif *blkif,
         if ((operation != READ) && vbd->readonly)
                 goto out;
 
-        if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
-                goto out;
+        if (likely(req->nr_sects)) {
+                blkif_sector_t end = req->sector_number + req->nr_sects;
+
+                if (unlikely(end < req->sector_number))
+                        goto out;
+                if (unlikely(end > vbd_sz(vbd)))
+                        goto out;
+        }
 
         req->dev  = vbd->pdevice;
         req->bdev = vbd->bdev;
@@ -538,11 +544,6 @@ static int dispatch_rw_block_io(struct xen_blkif *blkif,
         case BLKIF_OP_FLUSH_DISKCACHE:
                 blkif->st_f_req++;
                 operation = WRITE_FLUSH;
-                /*
-                 * The frontend likes to set this to -1, which xen_vbd_translate
-                 * is alergic too.
-                 */
-                req->u.rw.sector_number = 0;
                 break;
         case BLKIF_OP_WRITE_BARRIER:
         default: