[Xen-changelog] [xen-unstable] minios: Fix bug when blkfront reading into zero-mapped buffer

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1201619907 0
# Node ID 1a357a1504b26755edfac3fe0a37ea805d071d3a
# Parent  233f40973e1d689d66b25e439b2f48524dd579ea
minios: Fix bug when blkfront reading into zero-mapped buffer
by just poking the page.
No need to use virtual_to_mfn() for the ring since that is a real page.

Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
---
 extras/mini-os/blkfront.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletion(-)

diff -r 233f40973e1d -r 1a357a1504b2 extras/mini-os/blkfront.c
--- a/extras/mini-os/blkfront.c Tue Jan 29 15:16:35 2008 +0000
+++ b/extras/mini-os/blkfront.c Tue Jan 29 15:18:27 2008 +0000
@@ -88,7 +88,7 @@ struct blkfront_dev *init_blkfront(char 
     SHARED_RING_INIT(s);
     FRONT_RING_INIT(&dev->ring, s, PAGE_SIZE);
 
-    dev->ring_ref = gnttab_grant_access(0,virtual_to_mfn(s),0);
+    dev->ring_ref = gnttab_grant_access(0,virt_to_mfn(s),0);
 
     evtchn_alloc_unbound_t op;
     op.dom = DOMID_SELF;
@@ -274,6 +274,11 @@ void blkfront_aio(struct blkfront_aiocb 
 
     for (j = 0; j < n; j++) {
        uintptr_t data = start + j * PAGE_SIZE;
+        if (!write) {
+            /* Trigger CoW if needed */
+            *(char*)data = 0;
+            barrier();
+        }
        aiocbp->gref[j] = req->seg[j].gref =
             gnttab_grant_access(0, virtual_to_mfn(data), write);
        req->seg[j].first_sect = 0;

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog