Zero copy send and receive fixes:

- On receive, vm_map_lookup() needs to trigger the creation of a shadow
  object.  To make that happen, call vm_map_lookup() with PROT_WRITE
  instead of PROT_READ in vm_pgmoveco().

- On send, a shadow object will be created by the vm_map_lookup() in
  vm_fault(), but vm_page_cowfault() will delete the original page from
  the backing object rather than simply letting the legacy COW mechanism
  take over.  In other words, the new page should be added to the shadow
  object rather than replacing the old page in the backing object.  (i.e.
  vm_page_cowfault() should not be called in this case.)  We accomplish
  this by making sure fs.object == fs.first_object before calling
  vm_page_cowfault() in vm_fault().

Submitted by:	gallatin, alc
Tested by:	ken

1 files changed, 1 insertions, 1 deletions

diff --git a/sys/kern/kern_subr.c b/sys/kern/kern_subr.c
index 6728e8d..a5d6d0f 100644
--- a/sys/kern/kern_subr.c
+++ b/sys/kern/kern_subr.c
@@ -87,7 +87,7 @@ vm_pgmoveco(vm_map_t mapa, vm_object_t srcobj, vm_offset_t kaddr,
 	kern_pg = PHYS_TO_VM_PAGE(vtophys(kaddr));
 
 	if ((vm_map_lookup(&map, uaddr,
-			   VM_PROT_READ, &entry, &uobject,
+			   VM_PROT_WRITE, &entry, &uobject,
 			   &upindex, &prot, &wired)) != KERN_SUCCESS) {
 		return(EFAULT);
 	}