xen/blkback: persistent-grants fixes

This patch contains fixes for persistent grants implementation v2:

 * handle == 0 is a valid handle, so initialize grants in blkback
   setting the handle to BLKBACK_INVALID_HANDLE instead of 0. Reported
   by Konrad Rzeszutek Wilk.

 * new_map is a boolean, use "true" or "false" instead of 1 and 0.
   Reported by Konrad Rzeszutek Wilk.

 * blkfront announces the persistent-grants feature as
   feature-persistent-grants, use feature-persistent instead which is
   consistent with blkback and the public Xen headers.

 * Add a consistency check in blkfront to make sure we don't try to
   access segments that have not been set.

Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
[v1: The new_map int->bool had already been changed]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 911d733d21b6..f1de806b0a63 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -852,6 +852,7 @@ static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
                 rq_for_each_segment(bvec, s->request, iter) {
                         BUG_ON((bvec->bv_offset + bvec->bv_len) > PAGE_SIZE);
                         i = offset >> PAGE_SHIFT;
+                        BUG_ON(i >= s->req.u.rw.nr_segments);
                         shared_data = kmap_atomic(
                                 pfn_to_page(s->grants_used[i]->pfn));
                         bvec_data = bvec_kmap_irq(bvec, &flags);
@@ -1069,7 +1070,7 @@ again:
                 goto abort_transaction;
         }
         err = xenbus_printf(xbt, dev->nodename,
-                            "feature-persistent-grants", "%u", 1);
+                            "feature-persistent", "%u", 1);
         if (err)
                 dev_warn(&dev->dev,
                          "writing persistent grants feature to xenbus");