1 files changed, 77 insertions, 0 deletions
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 1c47fa7..21e7d7b 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1775,6 +1775,83 @@ vm_object_set_writeable_dirty(vm_object_t object)
 	}
 }
 
+/*
+ * Performs the copy_on_write operations necessary to allow the virtual copies
+ * into user space to work.  This has to be called for write(2) system calls
+ * from other processes, file unlinking, and file size shrinkage.
+ */
+void
+vm_freeze_copyopts(vm_object_t object, vm_pindex_t froma, vm_pindex_t toa)
+{
+	int rv;
+	vm_object_t robject;
+	vm_pindex_t idx;
+
+	GIANT_REQUIRED;
+	if ((object == NULL) ||
+		((object->flags & OBJ_OPT) == 0))
+		return;
+
+	if (object->shadow_count > object->ref_count)
+		panic("vm_freeze_copyopts: sc > rc");
+
+	while ((robject = TAILQ_FIRST(&object->shadow_head)) != NULL) {
+		vm_pindex_t bo_pindex;
+		vm_page_t m_in, m_out;
+
+		bo_pindex = OFF_TO_IDX(robject->backing_object_offset);
+
+		vm_object_reference(robject);
+
+		vm_object_pip_wait(robject, "objfrz");
+
+		if (robject->ref_count == 1) {
+			vm_object_deallocate(robject);
+			continue;
+		}
+
+		vm_object_pip_add(robject, 1);
+
+		for (idx = 0; idx < robject->size; idx++) {
+
+			m_out = vm_page_grab(robject, idx,
+						VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
+
+			if (m_out->valid == 0) {
+				m_in = vm_page_grab(object, bo_pindex + idx,
+						VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
+				if (m_in->valid == 0) {
+					rv = vm_pager_get_pages(object, &m_in, 1, 0);
+					if (rv != VM_PAGER_OK) {
+						printf("vm_freeze_copyopts: cannot read page from file: %lx\n", (long)m_in->pindex);
+						continue;
+					}
+					vm_page_deactivate(m_in);
+				}
+
+				vm_page_protect(m_in, VM_PROT_NONE);
+				pmap_copy_page(m_in, m_out);
+				m_out->valid = m_in->valid;
+				vm_page_dirty(m_out);
+				vm_page_activate(m_out);
+				vm_page_wakeup(m_in);
+			}
+			vm_page_wakeup(m_out);
+		}
+
+		object->shadow_count--;
+		object->ref_count--;
+		TAILQ_REMOVE(&object->shadow_head, robject, shadow_list);
+		robject->backing_object = NULL;
+		robject->backing_object_offset = 0;
+
+		vm_object_pip_wakeup(robject);
+		vm_object_deallocate(robject);
+	}
+
+	vm_object_clear_flag(object, OBJ_OPT);
+}
+
 #include "opt_ddb.h"
 #ifdef DDB
 #include <sys/kernel.h>