From e5f299ff760fec7221780cc019707658969a57d4 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Sun, 28 Apr 2013 19:25:09 +0000
Subject: [PATCH] Make vm_object_page_clean() and vm_mmap_vnode() tolerate the
 vnode' v_object of non OBJT_VNODE type.

For vm_object_page_clean(), simply do not assert that object type must
be OBJT_VNODE, and add a comment explaining how the check for
OBJ_MIGHTBEDIRTY prevents the rest of function from operating on such
objects.

For vm_mmap_vnode(), if the object type is not OBJT_VNODE, require it
to be for swap pager (or default), handle the bypass filesystems, and
correctly acquire the object reference in this case.

Reviewed by:	alc
Tested by:	pho, bf
MFC after:	1 week
---
 sys/vm/vm_mmap.c   | 11 +++++++++--
 sys/vm/vm_object.c |  7 ++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/sys/vm/vm_mmap.c b/sys/vm/vm_mmap.c
index c17e9cee9ce6..ef63f850ed00 100644
--- a/sys/vm/vm_mmap.c
+++ b/sys/vm/vm_mmap.c
@@ -1284,7 +1284,7 @@ vm_mmap_vnode(struct thread *td, vm_size_t objsize,
 			error = EINVAL;
 			goto done;
 		}
-		if (obj->handle != vp) {
+		if (obj->type == OBJT_VNODE && obj->handle != vp) {
 			vput(vp);
 			vp = (struct vnode *)obj->handle;
 			/*
@@ -1333,7 +1333,14 @@ vm_mmap_vnode(struct thread *td, vm_size_t objsize,
 	objsize = round_page(va.va_size);
 	if (va.va_nlink == 0)
 		flags |= MAP_NOSYNC;
-	obj = vm_pager_allocate(OBJT_VNODE, vp, objsize, prot, foff, cred);
+	if (obj->type == OBJT_VNODE)
+		obj = vm_pager_allocate(OBJT_VNODE, vp, objsize, prot, foff,
+		    cred);
+	else {
+		KASSERT(obj->type == OBJT_DEFAULT || obj->type == OBJT_SWAP,
+		    ("wrong object type"));
+		vm_object_reference(obj);
+	}
 	if (obj == NULL) {
 		error = ENOMEM;
 		goto done;
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 3d9ec616b18c..1f7cb7881a8b 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -820,7 +820,12 @@ vm_object_page_clean(vm_object_t object, vm_ooffset_t start, vm_ooffset_t end,
 	boolean_t clearobjflags, eio, res;
 
 	VM_OBJECT_ASSERT_WLOCKED(object);
-	KASSERT(object->type == OBJT_VNODE, ("Not a vnode object"));
+
+	/*
+	 * The OBJ_MIGHTBEDIRTY flag is only set for OBJT_VNODE
+	 * objects.  The check below prevents the function from
+	 * operating on non-vnode objects.
+	 */
 	if ((object->flags & OBJ_MIGHTBEDIRTY) == 0 ||
 	    object->resident_page_count == 0)
 		return (TRUE);