In the author's words:

These diffs implement the first stage of a VOP_{GET|PUT}PAGES pushdown
for local media FS's.

See ffs_putpages in /sys/ufs/ufs/ufs_readwrite.c for implementation
details for generic *_{get|put}pages for local media FS's.  Support
is trivial to add for any FS that formerly relied on the default
behaviour of the vnode_pager in in EOPNOTSUPP cases (just copy the
ffs_getpages() code for the FS in question's *_{get|put}pages).

Obviously, it would be better if each local media FS implemented a
more optimal method, instead of calling an exported interface from
the /sys/vm/vnode_pager.c, but this is a necessary first step in
getting the FS's to a point where they can be supplied with better
implementations on a case-by-case basis.

Obviously, the cd9660_putpages() can be rather trivial (since it
is a read-only FS type 8-)).

A slight (temporary) modification is made to print a diagnostic message
in the case where the underlying filesystem attempts to engage in the
previous behaviour.  Failure is likely to be ungraceful.

Submitted by:	terry@freebsd.org (Terry Lambert)

sys/ufs/ffs/ffs_vnops.c

@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)ffs_vnops.c	8.15 (Berkeley) 5/14/95
- * $Id: ffs_vnops.c,v 1.41 1998/02/04 22:33:33 eivind Exp $
+ * $Id: ffs_vnops.c,v 1.42 1998/02/06 12:14:16 eivind Exp $
  */
 
 #include <sys/param.h>
@@ -62,6 +62,7 @@
 
 static int	ffs_fsync __P((struct vop_fsync_args *));
 static int	ffs_getpages __P((struct vop_getpages_args *));
+static int	ffs_putpages __P((struct vop_putpages_args *));
 static int	ffs_read __P((struct vop_read_args *));
 static int	ffs_write __P((struct vop_write_args *));
 
@@ -71,6 +72,7 @@ static struct vnodeopv_entry_desc ffs_vnodeop_entries[] = {
 	{ &vop_default_desc,		(vop_t *) ufs_vnoperate },
 	{ &vop_fsync_desc,		(vop_t *) ffs_fsync },
 	{ &vop_getpages_desc,		(vop_t *) ffs_getpages },
+	{ &vop_putpages_desc,		(vop_t *) ffs_putpages },
 	{ &vop_read_desc,		(vop_t *) ffs_read },
 	{ &vop_reallocblks_desc,	(vop_t *) ffs_reallocblks },
 	{ &vop_write_desc,		(vop_t *) ffs_write },

sys/ufs/ufs/ufs_readwrite.c

@@ -31,7 +31,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)ufs_readwrite.c	8.11 (Berkeley) 5/8/95
- * $Id: ufs_readwrite.c,v 1.41 1998/01/30 11:34:05 phk Exp $
+ * $Id: ufs_readwrite.c,v 1.42 1998/02/05 03:32:33 dyson Exp $
  */
 
 #define	BLKSIZE(a, b, c)	blksize(a, b, c)
@@ -539,3 +539,17 @@ ffs_getpages(ap)
 
 	return (rtval);
 }
+
+/*
+ * put page routine
+ *
+ * XXX By default, wimp out... note that a_offset is ignored (and always
+ * XXX has been).
+ */
+int
+ffs_putpages(ap)
+	struct vop_putpages_args *ap;
+{
+	return vnode_pager_generic_putpages(ap->a_vp, ap->a_m, ap->a_count,
+		ap->a_sync, ap->a_rtvals);
+}

sys/vm/vnode_pager.c

@@ -38,7 +38,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)vnode_pager.c	7.5 (Berkeley) 4/20/91
- *	$Id: vnode_pager.c,v 1.85 1998/02/23 08:22:48 dyson Exp $
+ *	$Id: vnode_pager.c,v 1.86 1998/02/25 03:55:53 dyson Exp $
  */
 
 /*
@@ -88,11 +88,6 @@ struct pagerops vnodepagerops = {
 	NULL
 };
 
-static int vnode_pager_leaf_getpages __P((vm_object_t object, vm_page_t *m,
-					  int count, int reqpage));
-static int vnode_pager_leaf_putpages __P((vm_object_t object, vm_page_t *m,
-					  int count, boolean_t sync,
-					  int *rtvals));
 
 /*
  * Allocate (or lookup) pager for a vnode.
@@ -519,6 +514,14 @@ vnode_pager_input_old(object, m)
  * generic vnode pager input routine
  */
 
+/*
+ * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
+ * implement their own VOP_GETPAGES, their VOP_GETPAGES should call to
+ * vnode_pager_generic_getpages() to implement the previous behaviour.
+ *
+ * All other FS's should use the bypass to get to the local media
+ * backing vp's VOP_GETPAGES.
+ */
 static int
 vnode_pager_getpages(object, m, count, reqpage)
 	vm_object_t object;
@@ -530,31 +533,43 @@ vnode_pager_getpages(object, m, count, reqpage)
 	struct vnode *vp;
 
 	vp = object->handle;
+	/* 
+	 * XXX temporary diagnostic message to help track stale FS code,
+	 * Returning EOPNOTSUPP from here may make things unhappy.
+	 */
 	rtval = VOP_GETPAGES(vp, m, count*PAGE_SIZE, reqpage, 0);
 	if (rtval == EOPNOTSUPP)
-		return vnode_pager_leaf_getpages(object, m, count, reqpage);
-	else
-		return rtval;
+	    printf("vnode_pager: *** WARNING *** stale FS code in system.\n");
+	return rtval;
 }
 
-static int
-vnode_pager_leaf_getpages(object, m, count, reqpage)
-	vm_object_t object;
+
+/*
+ * This is now called from local media FS's to operate against their
+ * own vnodes if they fail to implement VOP_GETPAGES.
+ */
+int
+vnode_pager_generic_getpages(vp, m, bytecount, reqpage)
+	struct vnode *vp;
 	vm_page_t *m;
-	int count;
+	int bytecount;
 	int reqpage;
 {
+	vm_object_t object;
 	vm_offset_t kva;
 	off_t foff;
 	int i, size, bsize, first, firstaddr;
-	struct vnode *dp, *vp;
+	struct vnode *dp;
 	int runpg;
 	int runend;
 	struct buf *bp;
 	int s;
+	int count;
 	int error = 0;
 
-	vp = object->handle;
+	object = vp->v_object;
+	count = bytecount / PAGE_SIZE;
+
 	if (vp->v_mount == NULL)
 		return VM_PAGER_BAD;
 
@@ -770,6 +785,14 @@ vnode_pager_leaf_getpages(object, m, count, reqpage)
 	return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
 }
 
+/*
+ * EOPNOTSUPP is no longer legal.  For local media VFS's that do not
+ * implement their own VOP_PUTPAGES, their VOP_PUTPAGES should call to
+ * vnode_pager_generic_putpages() to implement the previous behaviour.
+ *
+ * All other FS's should use the bypass to get to the local media
+ * backing vp's VOP_PUTPAGES.
+ */
 static int
 vnode_pager_putpages(object, m, count, sync, rtvals)
 	vm_object_t object;
@@ -782,34 +805,35 @@ vnode_pager_putpages(object, m, count, sync, rtvals)
 	struct vnode *vp;
 
 	vp = object->handle;
-	rtval = VOP_PUTPAGES(vp, m, count*PAGE_SIZE, sync, rtvals, 0);
-	if (rtval == EOPNOTSUPP)
-		return vnode_pager_leaf_putpages(object, m, count, sync, rtvals);
-	else
-		return rtval;
+	return VOP_PUTPAGES(vp, m, count*PAGE_SIZE, sync, rtvals, 0);
 }
 
+
 /*
- * generic vnode pager output routine
+ * This is now called from local media FS's to operate against their
+ * own vnodes if they fail to implement VOP_GETPAGES.
  */
-static int
-vnode_pager_leaf_putpages(object, m, count, sync, rtvals)
-	vm_object_t object;
+int
+vnode_pager_generic_putpages(vp, m, bytecount, sync, rtvals)
+	struct vnode *vp;
 	vm_page_t *m;
-	int count;
+	int bytecount;
 	boolean_t sync;
 	int *rtvals;
 {
 	int i;
+	vm_object_t object;
+	int count;
 
-	struct vnode *vp;
 	int maxsize, ncount;
 	vm_ooffset_t poffset;
 	struct uio auio;
 	struct iovec aiov;
 	int error;
 
-	vp = object->handle;;
+	object = vp->v_object;
+	count = bytecount / PAGE_SIZE;
+
 	for (i = 0; i < count; i++)
 		rtvals[i] = VM_PAGER_AGAIN;
 

sys/vm/vnode_pager.h

@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)vnode_pager.h	8.1 (Berkeley) 6/11/93
- * $Id$
+ * $Id: vnode_pager.h,v 1.10 1997/02/22 09:48:43 peter Exp $
  */
 
 #ifndef	_VNODE_PAGER_
@@ -46,6 +46,16 @@
 vm_object_t vnode_pager_alloc __P((void *, vm_size_t, vm_prot_t, vm_ooffset_t));
 void vnode_pager_freepage __P((vm_page_t m));
 struct vnode *vnode_pager_lock __P((vm_object_t));
+
+/*
+ * XXX Generic routines; currently called by badly written FS code; these
+ * XXX should go away soon.
+ */
+int vnode_pager_generic_getpages __P((struct vnode *vp, vm_page_t *m,
+					  int count, int reqpage));
+int vnode_pager_generic_putpages __P((struct vnode *vp, vm_page_t *m,
+					  int count, boolean_t sync,
+					  int *rtvals));
 #endif
 
 #endif				/* _VNODE_PAGER_ */