diff --git a/share/man/man9/vfssubr.9 b/share/man/man9/vfssubr.9
index 2621a36e9c88..b7b428a25a3f 100644
--- a/share/man/man9/vfssubr.9
+++ b/share/man/man9/vfssubr.9
@@ -1,4 +1,4 @@
-.\"     $NetBSD: vfssubr.9,v 1.20 2010/12/02 12:54:13 wiz Exp $
+.\"     $NetBSD: vfssubr.9,v 1.21 2014/02/22 10:05:54 hannken Exp $
 .\"
 .\" Copyright (c) 2003, 2005, 2006 The NetBSD Foundation, Inc.
 .\" All rights reserved.
@@ -27,7 +27,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd May 9, 2009
+.Dd February 22, 2014
 .Dt VFSSUBR 9
 .Os
 .Sh NAME
@@ -74,9 +74,9 @@
 .Ft void
 .Fn vfs_unmountall  "struct lwp *l"
 .Ft int
-.Fn vfs_busy "struct mount *mp" "int flags" "struct simplelock *interlkp"
+.Fn vfs_busy "struct mount *mp" "struct mount **nextp"
 .Ft void
-.Fn vfs_unbusy "struct mount *mp"
+.Fn vfs_unbusy "struct mount *mp" "bool keepref" "struct mount **nextp"
 .Ft struct mount *
 .Fn vfs_mountalloc "struct vfsops *vfs" "struct vnode *vp"
 .Ft int
@@ -130,17 +130,38 @@ by the vnode
 Mount the root file system.
 .It Fn vfs_unmountall "l"
 Unmount all file systems.
-.It Fn vfs_busy "mp" "flags" "interlkp"
+.It Fn vfs_busy "mp" "nextp"
 Mark the mount point specified by
 .Fa mp
-as busy.
+as busy and get a reference to it.
 This function is used to synchronize access and to delay unmounting.
-The interlock specified by argument
-.Fa interlkp
-is not released on failure.
-.It Fn vfs_unbusy "mp"
-Free the busy file system specified by the mount structure
+The caller must hold a pre-existing reference to the mount.
+If
+.Fa nextp
+is not NULL, the caller must hold the
+.Em mountlist_lock
+and
+.Fa nextp
+will receive the next mount from mount list on error.
+The
+.Em mountlist_lock
+is released on return.
+.It Fn vfs_unbusy "mp" "keepref" "nextp"
+Undo a
+.Fn vfs_busy
+on the mount point specified by
 .Fa mp .
+If
+.Fa keepref
+is true, preserve the reference added by
+.Fn vfs_busy .
+If
+.Fa nextp
+is not NULL, the
+.Em mountlist_lock
+will be aquired and
+.Fa nextp
+will receive the next mount from mount list.
 .It Fn vfs_mountalloc "vfsops" "vp"
 Allocate and initialise a mount structure, setting
 .Em mnt_vnodecovered