The big 4.4BSD Lite to FreeBSD 2.0.0 (Development) patch.

Reviewed by:	Rodney W. Grimes
Submitted by:	John Dyson and David Greenman

1 files changed, 1089 insertions, 245 deletions

diff --git a/sys/vm/vnode_pager.c b/sys/vm/vnode_pager.c
index 9c2f826..b8e5a19 100644
--- a/sys/vm/vnode_pager.c
+++ b/sys/vm/vnode_pager.c
@@ -1,7 +1,8 @@
 /*
  * Copyright (c) 1990 University of Utah.
- * Copyright (c) 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
+ * Copyright (c) 1991 The Regents of the University of California.
+ * All rights reserved.
+ * Copyright (c) 1993,1994 John S. Dyson
  *
  * This code is derived from software contributed to Berkeley by
  * the Systems Programming Group of the University of Utah Computer
@@ -35,7 +36,8 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)vnode_pager.c	8.8 (Berkeley) 2/13/94
+ *	from: @(#)vnode_pager.c	7.5 (Berkeley) 4/20/91
+ *	$Id: vnode_pager.c,v 1.17 1994/04/05 03:23:53 davidg Exp $
  */
 
 /*
@@ -46,6 +48,24 @@
  *	fix credential use (uses current process credentials now)
  */
 
+/*
+ * MODIFICATIONS:
+ * John S. Dyson  08 Dec 93
+ *
+ * This file in conjunction with some vm_fault mods, eliminate the performance
+ * advantage for using the buffer cache and minimize memory copies.
+ *
+ * 1) Supports multiple - block reads
+ * 2) Bypasses buffer cache for reads
+ * 
+ * TODO:
+ *
+ * 1) Totally bypass buffer cache for reads
+ *    (Currently will still sometimes use buffer cache for reads)
+ * 2) Bypass buffer cache for writes
+ *    (Code does not support it, but mods are simple)
+ */
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/proc.h>
@@ -58,51 +78,44 @@
 #include <vm/vm_page.h>
 #include <vm/vnode_pager.h>
 
-struct pagerlst	vnode_pager_list;	/* list of managed vnodes */
+#include <sys/buf.h>
+#include <miscfs/specfs/specdev.h>
 
-#ifdef DEBUG
-int	vpagerdebug = 0x00;
-#define	VDB_FOLLOW	0x01
-#define VDB_INIT	0x02
-#define VDB_IO		0x04
-#define VDB_FAIL	0x08
-#define VDB_ALLOC	0x10
-#define VDB_SIZE	0x20
-#endif
+int vnode_pager_putmulti();
 
-static vm_pager_t	 vnode_pager_alloc
-			    __P((caddr_t, vm_size_t, vm_prot_t, vm_offset_t));
-static void		 vnode_pager_cluster
-			    __P((vm_pager_t, vm_offset_t,
-				 vm_offset_t *, vm_offset_t *));
-static void		 vnode_pager_dealloc __P((vm_pager_t));
-static int		 vnode_pager_getpage
-			    __P((vm_pager_t, vm_page_t *, int, boolean_t));
-static boolean_t	 vnode_pager_haspage __P((vm_pager_t, vm_offset_t));
-static void		 vnode_pager_init __P((void));
-static int		 vnode_pager_io
-			    __P((vn_pager_t, vm_page_t *, int,
-				 boolean_t, enum uio_rw));
-static boolean_t	 vnode_pager_putpage
-			    __P((vm_pager_t, vm_page_t *, int, boolean_t));
+void		vnode_pager_init();
+vm_pager_t	vnode_pager_alloc(caddr_t, vm_offset_t, vm_prot_t, vm_offset_t);
+void		vnode_pager_dealloc();
+int		vnode_pager_getpage();
+int		vnode_pager_getmulti();
+int		vnode_pager_putpage();
+boolean_t	vnode_pager_haspage();
 
 struct pagerops vnodepagerops = {
 	vnode_pager_init,
 	vnode_pager_alloc,
 	vnode_pager_dealloc,
 	vnode_pager_getpage,
+	vnode_pager_getmulti,
 	vnode_pager_putpage,
-	vnode_pager_haspage,
-	vnode_pager_cluster
+	vnode_pager_putmulti,
+	vnode_pager_haspage
 };
 
-static void
+static int vnode_pager_input(vn_pager_t vnp, vm_page_t *m, int count, int reqpage);
+static int vnode_pager_output(vn_pager_t vnp, vm_page_t *m, int count, int *rtvals);
+struct buf * getpbuf() ;
+void relpbuf(struct buf *bp) ;
+
+extern vm_map_t pager_map;
+
+struct pagerlst vnode_pager_list;	/* list of managed vnodes */
+
+#define MAXBP (PAGE_SIZE/DEV_BSIZE);
+
+void
 vnode_pager_init()
 {
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_init()\n");
-#endif
 	TAILQ_INIT(&vnode_pager_list);
 }
 
@@ -110,12 +123,12 @@ vnode_pager_init()
  * Allocate (or lookup) pager for a vnode.
  * Handle is a vnode pointer.
  */
-static vm_pager_t
-vnode_pager_alloc(handle, size, prot, foff)
+vm_pager_t
+vnode_pager_alloc(handle, size, prot, offset)
 	caddr_t handle;
 	vm_size_t size;
 	vm_prot_t prot;
-	vm_offset_t foff;
+	vm_offset_t offset;
 {
 	register vm_pager_t pager;
 	register vn_pager_t vnp;
@@ -124,10 +137,6 @@ vnode_pager_alloc(handle, size, prot, foff)
 	struct vnode *vp;
 	struct proc *p = curproc;	/* XXX */
 
-#ifdef DEBUG
-	if (vpagerdebug & (VDB_FOLLOW|VDB_ALLOC))
-		printf("vnode_pager_alloc(%x, %x, %x)\n", handle, size, prot);
-#endif
 	/*
 	 * Pageout to vnode, no can do yet.
 	 */
@@ -171,12 +180,12 @@ vnode_pager_alloc(handle, size, prot, foff)
 		vnp->vnp_flags = 0;
 		vnp->vnp_vp = vp;
 		vnp->vnp_size = vattr.va_size;
+
 		TAILQ_INSERT_TAIL(&vnode_pager_list, pager, pg_list);
 		pager->pg_handle = handle;
 		pager->pg_type = PG_VNODE;
-		pager->pg_flags = 0;
 		pager->pg_ops = &vnodepagerops;
-		pager->pg_data = vnp;
+		pager->pg_data = (caddr_t)vnp;
 		vp->v_vmdata = (caddr_t)pager;
 	} else {
 		/*
@@ -184,121 +193,104 @@ vnode_pager_alloc(handle, size, prot, foff)
 		 * cache if found and also gain a reference to the object.
 		 */
 		object = vm_object_lookup(pager);
-#ifdef DEBUG
-		vnp = (vn_pager_t)pager->pg_data;
-#endif
 	}
-#ifdef DEBUG
-	if (vpagerdebug & VDB_ALLOC)
-		printf("vnode_pager_setup: vp %x sz %x pager %x object %x\n",
-		       vp, vnp->vnp_size, pager, object);
-#endif
 	return(pager);
 }
 
-static void
+void
 vnode_pager_dealloc(pager)
 	vm_pager_t pager;
 {
 	register vn_pager_t vnp = (vn_pager_t)pager->pg_data;
 	register struct vnode *vp;
-#ifdef NOTDEF
 	struct proc *p = curproc;		/* XXX */
-#endif
 
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_dealloc(%x)\n", pager);
-#endif
 	if (vp = vnp->vnp_vp) {
 		vp->v_vmdata = NULL;
 		vp->v_flag &= ~VTEXT;
-#if NOTDEF
+#if 0
 		/* can hang if done at reboot on NFS FS */
 		(void) VOP_FSYNC(vp, p->p_ucred, p);
 #endif
 		vrele(vp);
 	}
+
 	TAILQ_REMOVE(&vnode_pager_list, pager, pg_list);
 	free((caddr_t)vnp, M_VMPGDATA);
 	free((caddr_t)pager, M_VMPAGER);
 }
 
-static int
-vnode_pager_getpage(pager, mlist, npages, sync)
+int
+vnode_pager_getmulti(pager, m, count, reqpage, sync)
+	vm_pager_t pager;
+	vm_page_t *m;
+	int count;
+	int reqpage;
+	boolean_t sync;
+{
+	
+	return vnode_pager_input((vn_pager_t) pager->pg_data, m, count, reqpage);
+}
+
+int
+vnode_pager_getpage(pager, m, sync)
 	vm_pager_t pager;
-	vm_page_t *mlist;
-	int npages;
+	vm_page_t m;
 	boolean_t sync;
 {
 
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_getpage(%x, %x, %x, %x)\n",
-		       pager, mlist, npages, sync);
-#endif
-	return(vnode_pager_io((vn_pager_t)pager->pg_data,
-			      mlist, npages, sync, UIO_READ));
+	int err;
+	vm_page_t marray[1];
+	if (pager == NULL)
+		return FALSE;
+	marray[0] = m;
+
+	return vnode_pager_input((vn_pager_t)pager->pg_data, marray, 1, 0);
 }
 
-static boolean_t
-vnode_pager_putpage(pager, mlist, npages, sync)
+boolean_t
+vnode_pager_putpage(pager, m, sync)
 	vm_pager_t pager;
-	vm_page_t *mlist;
-	int npages;
+	vm_page_t m;
 	boolean_t sync;
 {
 	int err;
+	vm_page_t marray[1];
+	int rtvals[1];
 
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_putpage(%x, %x, %x, %x)\n",
-		       pager, mlist, npages, sync);
-#endif
 	if (pager == NULL)
-		return (FALSE);			/* ??? */
-	err = vnode_pager_io((vn_pager_t)pager->pg_data,
-			     mlist, npages, sync, UIO_WRITE);
-	/*
-	 * If the operation was successful, mark the pages clean.
-	 */
-	if (err == VM_PAGER_OK) {
-		while (npages--) {
-			(*mlist)->flags |= PG_CLEAN;
-			pmap_clear_modify(VM_PAGE_TO_PHYS(*mlist));
-			mlist++;
-		}
-	}
-	return(err);
+		return FALSE;
+	marray[0] = m;
+	vnode_pager_output((vn_pager_t)pager->pg_data, marray, 1, rtvals);
+	return rtvals[0];
+}
+
+int
+vnode_pager_putmulti(pager, m, c, sync, rtvals)
+	vm_pager_t pager;
+	vm_page_t *m;
+	int c;
+	boolean_t sync;
+	int *rtvals;
+{
+	return vnode_pager_output((vn_pager_t)pager->pg_data, m, c, rtvals);
 }
 
-static boolean_t
+
+boolean_t
 vnode_pager_haspage(pager, offset)
 	vm_pager_t pager;
 	vm_offset_t offset;
 {
 	register vn_pager_t vnp = (vn_pager_t)pager->pg_data;
 	daddr_t bn;
+	int run;
 	int err;
 
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_haspage(%x, %x)\n", pager, offset);
-#endif
-
 	/*
 	 * Offset beyond end of file, do not have the page
-	 * Lock the vnode first to make sure we have the most recent
-	 * version of the size.
 	 */
-	VOP_LOCK(vnp->vnp_vp);
 	if (offset >= vnp->vnp_size) {
-		VOP_UNLOCK(vnp->vnp_vp);
-#ifdef DEBUG
-		if (vpagerdebug & (VDB_FAIL|VDB_SIZE))
-			printf("vnode_pager_haspage: pg %x, off %x, size %x\n",
-			       pager, offset, vnp->vnp_size);
-#endif
 		return(FALSE);
 	}
 
@@ -311,53 +303,14 @@ vnode_pager_haspage(pager, offset)
 	 */
 	err = VOP_BMAP(vnp->vnp_vp,
 		       offset / vnp->vnp_vp->v_mount->mnt_stat.f_iosize,
-		       (struct vnode **)0, &bn, NULL);
-	VOP_UNLOCK(vnp->vnp_vp);
+		       (struct vnode **)0, &bn, 0);
 	if (err) {
-#ifdef DEBUG
-		if (vpagerdebug & VDB_FAIL)
-			printf("vnode_pager_haspage: BMAP err %d, pg %x, off %x\n",
-			       err, pager, offset);
-#endif
 		return(TRUE);
 	}
 	return((long)bn < 0 ? FALSE : TRUE);
 }
 
-static void
-vnode_pager_cluster(pager, offset, loffset, hoffset)
-	vm_pager_t	pager;
-	vm_offset_t	offset;
-	vm_offset_t	*loffset;
-	vm_offset_t	*hoffset;
-{
-	vn_pager_t vnp = (vn_pager_t)pager->pg_data;
-	vm_offset_t loff, hoff;
-
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_cluster(%x, %x) ", pager, offset);
-#endif
-	loff = offset;
-	if (loff >= vnp->vnp_size)
-		panic("vnode_pager_cluster: bad offset");
-	/*
-	 * XXX could use VOP_BMAP to get maxcontig value
-	 */
-	hoff = loff + MAXBSIZE;
-	if (hoff > round_page(vnp->vnp_size))
-		hoff = round_page(vnp->vnp_size);
-
-	*loffset = loff;
-	*hoffset = hoff;
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("returns [%x-%x]\n", loff, hoff);
-#endif
-}
-
 /*
- * (XXX)
  * Lets the VM system know about a change in size for a file.
  * If this vnode is mapped into some address space (i.e. we have a pager
  * for it) we adjust our own internal size and flush any cached pages in
@@ -399,19 +352,14 @@ vnode_pager_setsize(vp, nsize)
 	if (object == NULL)
 		return;
 
-#ifdef DEBUG
-	if (vpagerdebug & (VDB_FOLLOW|VDB_SIZE))
-		printf("vnode_pager_setsize: vp %x obj %x osz %d nsz %d\n",
-		       vp, object, vnp->vnp_size, nsize);
-#endif
 	/*
 	 * File has shrunk.
 	 * Toss any cached pages beyond the new EOF.
 	 */
-	if (nsize < vnp->vnp_size) {
+	if (round_page(nsize) < round_page(vnp->vnp_size)) {
 		vm_object_lock(object);
 		vm_object_page_remove(object,
-				      (vm_offset_t)nsize, vnp->vnp_size);
+				      (vm_offset_t)round_page(nsize), round_page(vnp->vnp_size));
 		vm_object_unlock(object);
 	}
 	vnp->vnp_size = (vm_offset_t)nsize;
@@ -425,24 +373,67 @@ vnode_pager_umount(mp)
 	register vm_pager_t pager, npager;
 	struct vnode *vp;
 
-	for (pager = vnode_pager_list.tqh_first; pager != NULL; pager = npager){
+	pager = vnode_pager_list.tqh_first;
+	while( pager) {
 		/*
 		 * Save the next pointer now since uncaching may
 		 * terminate the object and render pager invalid
 		 */
-		npager = pager->pg_list.tqe_next;
 		vp = ((vn_pager_t)pager->pg_data)->vnp_vp;
-		if (mp == (struct mount *)0 || vp->v_mount == mp) {
-			VOP_LOCK(vp);
+		npager = pager->pg_list.tqe_next;
+		if (mp == (struct mount *)0 || vp->v_mount == mp)
 			(void) vnode_pager_uncache(vp);
-			VOP_UNLOCK(vp);
-		}
+		pager = npager;
 	}
 }
 
 /*
  * Remove vnode associated object from the object cache.
  *
+ * Note: this routine may be invoked as a result of a pager put
+ * operation (possibly at object termination time), so we must be careful.
+ */
+boolean_t
+vnode_pager_uncache(vp)
+	register struct vnode *vp;
+{
+	register vm_object_t object;
+	boolean_t uncached, locked;
+	vm_pager_t pager;
+
+	/*
+	 * Not a mapped vnode
+	 */
+	pager = (vm_pager_t)vp->v_vmdata;
+	if (pager == NULL)
+		return (TRUE);
+	/*
+	 * Unlock the vnode if it is currently locked.
+	 * We do this since uncaching the object may result
+	 * in its destruction which may initiate paging
+	 * activity which may necessitate locking the vnode.
+	 */
+	locked = VOP_ISLOCKED(vp);
+	if (locked)
+		VOP_UNLOCK(vp);
+	/*
+	 * Must use vm_object_lookup() as it actually removes
+	 * the object from the cache list.
+	 */
+	object = vm_object_lookup(pager);
+	if (object) {
+		uncached = (object->ref_count <= 1);
+		pager_cache(object, FALSE);
+	} else
+		uncached = TRUE;
+	if (locked)
+		VOP_LOCK(vp);
+	return(uncached);
+}
+#if 0
+/*
+ * Remove vnode associated object from the object cache.
+ *
  * XXX unlock the vnode if it is currently locked.
  * We must do this since uncaching the object may result in its
  * destruction which may initiate paging activity which may necessitate
@@ -462,14 +453,6 @@ vnode_pager_uncache(vp)
 	pager = (vm_pager_t)vp->v_vmdata;
 	if (pager == NULL)
 		return (TRUE);
-#ifdef DEBUG
-	if (!VOP_ISLOCKED(vp)) {
-		extern int (**nfsv2_vnodeop_p)();
-
-		if (vp->v_op != nfsv2_vnodeop_p)
-			panic("vnode_pager_uncache: vnode not locked!");
-	}
-#endif
 	/*
 	 * Must use vm_object_lookup() as it actually removes
 	 * the object from the cache list.
@@ -484,97 +467,958 @@ vnode_pager_uncache(vp)
 		uncached = TRUE;
 	return(uncached);
 }
+#endif
 
-static int
-vnode_pager_io(vnp, mlist, npages, sync, rw)
-	register vn_pager_t vnp;
-	vm_page_t *mlist;
-	int npages;
-	boolean_t sync;
-	enum uio_rw rw;
+
+void
+vnode_pager_freepage(m)
+	vm_page_t m;
+{
+	PAGE_WAKEUP(m);
+	vm_page_free(m);
+}
+
+/*
+ * calculate the linear (byte) disk address of specified virtual
+ * file address
+ */
+vm_offset_t
+vnode_pager_addr(vp, address)
+	struct vnode *vp;
+	vm_offset_t address;
+{
+	int rtaddress;
+	int bsize;
+	vm_offset_t block;
+	struct vnode *rtvp;
+	int err;
+	int vblock, voffset;
+	int run;
+
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+	vblock = address / bsize;
+	voffset = address % bsize;
+
+	err = VOP_BMAP(vp,vblock,&rtvp,&block,0);
+
+	if( err)
+		rtaddress = -1;
+	else
+		rtaddress = block * DEV_BSIZE + voffset;
+
+	return rtaddress;
+}
+
+/*
+ * interrupt routine for I/O completion
+ */
+void
+vnode_pager_iodone(bp)
+	struct buf *bp;
 {
+	bp->b_flags |= B_DONE;
+	wakeup((caddr_t)bp);
+}
+
+/*
+ * small block file system vnode pager input
+ */
+int
+vnode_pager_input_smlfs(vnp, m)
+	vn_pager_t vnp;
+	vm_page_t m;
+{
+	int i;
+	int s;
+	vm_offset_t paging_offset;
+	struct vnode *dp, *vp;
+	struct buf *bp;
+	vm_offset_t mapsize;
+	vm_offset_t foff;
+	vm_offset_t kva;
+	int fileaddr;
+	int block;
+	vm_offset_t bsize;
+	int error = 0;
+	int run;
+
+	paging_offset = m->object->paging_offset;
+	vp = vnp->vnp_vp;
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+	foff = m->offset + paging_offset;
+
+	VOP_BMAP(vp, foff, &dp, 0, 0);
+
+	kva = vm_pager_map_page(m);
+
+	for(i=0;i<PAGE_SIZE/bsize;i++) {
+	/*
+	 * calculate logical block and offset
+	 */
+		block = foff / bsize + i;
+		s = splbio();
+		while (bp = incore(vp, block)) {
+			int amount;
+
+	/*
+	 * wait until the buffer is avail or gone
+	 */
+			if (bp->b_flags & B_BUSY) {
+				bp->b_flags |= B_WANTED;
+				tsleep ((caddr_t)bp, PVM, "vnwblk", 0);
+				continue;
+			}
+
+			amount = bsize;
+			if ((foff + bsize) > vnp->vnp_size)
+				amount = vnp->vnp_size - foff;
+
+		/*
+		 * make sure that this page is in the buffer
+		 */
+			if ((amount > 0) && amount <= bp->b_bcount) {
+				bp->b_flags |= B_BUSY;
+				splx(s);
+
+			/*
+			 * copy the data from the buffer
+			 */
+				bcopy(bp->b_un.b_addr, (caddr_t)kva + i * bsize, amount);
+				if (amount < bsize) {
+					bzero((caddr_t)kva + amount, bsize - amount);
+				}
+				bp->b_flags &= ~B_BUSY;
+				wakeup((caddr_t)bp);
+				goto nextblock;
+			}
+			break;
+		}
+		splx(s);
+		fileaddr = vnode_pager_addr(vp, foff + i * bsize);
+		if( fileaddr != -1) {
+			bp = getpbuf();
+			VHOLD(vp);
+
+	/* build a minimal buffer header */
+			bp->b_flags = B_BUSY | B_READ | B_CALL;
+			bp->b_iodone = vnode_pager_iodone;
+			bp->b_proc = curproc;
+			bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
+			if( bp->b_rcred != NOCRED)
+				crhold(bp->b_rcred);
+			if( bp->b_wcred != NOCRED)
+				crhold(bp->b_wcred);
+			bp->b_un.b_addr = (caddr_t) kva + i * bsize;
+			bp->b_blkno = fileaddr / DEV_BSIZE;
+			bgetvp(dp, bp);
+			bp->b_bcount = bsize;
+			bp->b_bufsize = bsize;
+	
+	/* do the input */
+			VOP_STRATEGY(bp);
+
+	/* we definitely need to be at splbio here */
+
+			s = splbio();
+			while ((bp->b_flags & B_DONE) == 0) {
+				tsleep((caddr_t)bp, PVM, "vnsrd", 0);
+			}
+			splx(s);
+			if ((bp->b_flags & B_ERROR) != 0)
+				error = EIO;
+
+	/*
+	 * free the buffer header back to the swap buffer pool
+	 */
+			relpbuf(bp);
+			HOLDRELE(vp);
+			if( error)
+				break;
+		} else {
+			bzero((caddr_t) kva + i * bsize, bsize);
+		}
+nextblock:
+	}
+	vm_pager_unmap_page(kva);
+	if( error) {
+		return VM_PAGER_FAIL;
+	}
+	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
+	m->flags |= PG_CLEAN;
+	m->flags &= ~PG_LAUNDRY;
+	return VM_PAGER_OK;
+
+}
+
+
+/*
+ * old style vnode pager output routine
+ */
+int
+vnode_pager_input_old(vnp, m)
+	vn_pager_t vnp;
+	vm_page_t m;
+{
+	int i;
 	struct uio auio;
 	struct iovec aiov;
+	int error;
+	int size;
+	vm_offset_t foff;
+	vm_offset_t kva;
+
+	error = 0;
+	foff = m->offset + m->object->paging_offset;
+	/*
+	 * Return failure if beyond current EOF
+	 */
+	if (foff >= vnp->vnp_size) {
+		return VM_PAGER_BAD;
+	} else {
+		size = PAGE_SIZE;
+		if (foff + size > vnp->vnp_size)
+			size = vnp->vnp_size - foff;
+/*
+ * Allocate a kernel virtual address and initialize so that
+ * we can use VOP_READ/WRITE routines.
+ */
+		kva = vm_pager_map_page(m);
+		aiov.iov_base = (caddr_t)kva;
+		aiov.iov_len = size;
+		auio.uio_iov = &aiov;
+		auio.uio_iovcnt = 1;
+		auio.uio_offset = foff;
+		auio.uio_segflg = UIO_SYSSPACE;
+		auio.uio_rw = UIO_READ;
+		auio.uio_resid = size;
+		auio.uio_procp = (struct proc *)0;
+
+		error = VOP_READ(vnp->vnp_vp, &auio, 0, curproc->p_ucred);
+		if (!error) {
+			register int count = size - auio.uio_resid;
+
+			if (count == 0)
+				error = EINVAL;
+			else if (count != PAGE_SIZE)
+				bzero((caddr_t)kva + count, PAGE_SIZE - count);
+		}
+		vm_pager_unmap_page(kva);
+	}
+	pmap_clear_modify(VM_PAGE_TO_PHYS(m));
+	m->flags |= PG_CLEAN;
+	m->flags &= ~PG_LAUNDRY;
+	return error?VM_PAGER_FAIL:VM_PAGER_OK;
+}
+
+/*
+ * generic vnode pager input routine
+ */
+int
+vnode_pager_input(vnp, m, count, reqpage)
+	register vn_pager_t vnp;
+	vm_page_t *m;
+	int count, reqpage;
+{
+	int i,j;
 	vm_offset_t kva, foff;
-	int error, size;
+	int size;
 	struct proc *p = curproc;		/* XXX */
+	vm_object_t object;
+	vm_offset_t paging_offset;
+	struct vnode *dp, *vp;
+	vm_offset_t mapsize;
+	int bsize;
+
+	int first, last;
+	int reqaddr, firstaddr;
+	int run;
+	int block, offset;
+
+	int nbp;
+	struct buf *bp;
+	int s;
+	int failflag;
+
+	int errtype=0; /* 0 is file type otherwise vm type */
+	int error = 0;
+
+	object = m[reqpage]->object;	/* all vm_page_t items are in same object */
+	paging_offset = object->paging_offset;
+
+	vp = vnp->vnp_vp;
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+
+	/* get the UNDERLYING device for the file with VOP_BMAP() */
+	/*
+	 * originally, we did not check for an error return
+	 * value -- assuming an fs always has a bmap entry point
+	 * -- that assumption is wrong!!!
+	 */
+	kva = 0;
+	mapsize = 0;
+	foff = m[reqpage]->offset + paging_offset;
+	if (!VOP_BMAP(vp, foff, &dp, 0, 0)) {
+		/*
+		 * we do not block for a kva, notice we default to a kva
+		 * conservative behavior
+		 */
+		kva = kmem_alloc_pageable(pager_map, (mapsize = count*PAGE_SIZE));
+		if( !kva) {
+			for (i = 0; i < count; i++) {
+				if (i != reqpage) {
+					vnode_pager_freepage(m[i]);
+				}
+			}
+			m[0] = m[reqpage];
+			kva = kmem_alloc_wait(pager_map, mapsize = PAGE_SIZE);
+			reqpage = 0;
+			count = 1;
+		}
+	}
 
-	/* XXX */
-	vm_page_t m;
-	if (npages != 1)
-		panic("vnode_pager_io: cannot handle multiple pages");
-	m = *mlist;
-	/* XXX */
-
-#ifdef DEBUG
-	if (vpagerdebug & VDB_FOLLOW)
-		printf("vnode_pager_io(%x, %x, %c): vnode %x\n",
-		       vnp, m, rw == UIO_READ ? 'R' : 'W', vnp->vnp_vp);
-#endif
-	foff = m->offset + m->object->paging_offset;
 	/*
-	 * Allocate a kernel virtual address and initialize so that
-	 * we can use VOP_READ/WRITE routines.
+	 * if we can't get a kva or we can't bmap, use old VOP code
 	 */
-	kva = vm_pager_map_pages(mlist, npages, sync);
-	if (kva == NULL)
-		return(VM_PAGER_AGAIN);
+	if (!kva) {
+		for (i = 0; i < count; i++) {
+			if (i != reqpage) {
+				vnode_pager_freepage(m[i]);
+			}
+		}
+		return vnode_pager_input_old(vnp, m[reqpage]);
 	/*
-	 * After all of the potentially blocking operations have been
-	 * performed, we can do the size checks:
-	 *	read beyond EOF (returns error)
-	 *	short read
+	 * if the blocksize is smaller than a page size, then use
+	 * special small filesystem code.  NFS sometimes has a small
+	 * blocksize, but it can handle large reads itself.
 	 */
-	VOP_LOCK(vnp->vnp_vp);
-	if (foff >= vnp->vnp_size) {
-		VOP_UNLOCK(vnp->vnp_vp);
-		vm_pager_unmap_pages(kva, npages);
-#ifdef DEBUG
-		if (vpagerdebug & VDB_SIZE)
-			printf("vnode_pager_io: vp %x, off %d size %d\n",
-			       vnp->vnp_vp, foff, vnp->vnp_size);
-#endif
-		return(VM_PAGER_BAD);
+	} else if( (PAGE_SIZE / bsize) > 1 &&
+		(vp->v_mount->mnt_stat.f_type != MOUNT_NFS)) {
+
+		kmem_free_wakeup(pager_map, kva, mapsize);
+
+		for (i = 0; i < count; i++) {
+			if (i != reqpage) {
+				vnode_pager_freepage(m[i]);
+			}
+		}
+		return vnode_pager_input_smlfs(vnp, m[reqpage]);
+	}
+
+/*
+ * here on direct device I/O
+ */
+
+
+	/*
+	 * This pathetic hack gets data from the buffer cache, if it's there.
+	 * I believe that this is not really necessary, and the ends can
+	 * be gotten by defaulting to the normal vfs read behavior, but this
+	 * might be more efficient, because the will NOT invoke read-aheads
+	 * and one of the purposes of this code is to bypass the buffer
+	 * cache and keep from flushing it by reading in a program.
+	 */
+	/*
+	 * calculate logical block and offset
+	 */
+	block = foff / bsize;
+	offset = foff % bsize;
+	s = splbio();
+
+	/*
+	 * if we have a buffer in core, then try to use it
+	 */
+	while (bp = incore(vp, block)) {
+		int amount;
+
+	/*
+	 * wait until the buffer is avail or gone
+	 */
+		if (bp->b_flags & B_BUSY) {
+			bp->b_flags |= B_WANTED;
+			tsleep ((caddr_t)bp, PVM, "vnwblk", 0);
+			continue;
+		}
+
+		amount = PAGE_SIZE;
+		if ((foff + amount) > vnp->vnp_size)
+			amount = vnp->vnp_size - foff;
+
+		/*
+		 * make sure that this page is in the buffer
+		 */
+		if ((amount > 0) && (offset + amount) <= bp->b_bcount) {
+			bp->b_flags |= B_BUSY;
+			splx(s);
+
+			/*
+			 * map the requested page
+			 */
+			pmap_kenter(kva, VM_PAGE_TO_PHYS(m[reqpage]));
+			pmap_update();
+
+			/*
+			 * copy the data from the buffer
+			 */
+			bcopy(bp->b_un.b_addr + offset, (caddr_t)kva, amount);
+			if (amount < PAGE_SIZE) {
+				bzero((caddr_t)kva + amount, PAGE_SIZE - amount);
+			}
+			/*
+			 * unmap the page and free the kva
+			 */
+			pmap_remove(vm_map_pmap(pager_map), kva, kva + PAGE_SIZE);
+			kmem_free_wakeup(pager_map, kva, mapsize);
+			/*
+			 * release the buffer back to the block subsystem
+			 */
+			bp->b_flags &= ~B_BUSY;
+			wakeup((caddr_t)bp);
+			/*
+			 * we did not have to do any work to get the requested
+			 * page, the read behind/ahead does not justify a read
+			 */
+			for (i = 0; i < count; i++) {
+				if (i != reqpage) {
+					vnode_pager_freepage(m[i]);
+				}
+			}
+			count = 1;
+			reqpage = 0;
+			m[0] = m[reqpage];
+
+			/*
+			 * sorry for the goto
+			 */
+			goto finishup;
+		}
+		/*
+		 * buffer is nowhere to be found, read from the disk
+		 */
+		break;
+	}
+	splx(s);
+
+	reqaddr = vnode_pager_addr(vp, foff);
+	s = splbio();
+	/*
+	 * Make sure that our I/O request is contiguous.
+	 * Scan backward and stop for the first discontiguous
+	 *	entry or stop for a page being in buffer cache.
+	 */
+	failflag = 0;
+	first = reqpage;
+	for (i = reqpage - 1; i >= 0; --i) {
+		if (failflag ||
+		   incore(vp, (foff + (i - reqpage) * PAGE_SIZE) / bsize) ||
+		   (vnode_pager_addr(vp, m[i]->offset + paging_offset))
+				!= reqaddr + (i - reqpage) * PAGE_SIZE) {
+			vnode_pager_freepage(m[i]);
+			failflag = 1;
+		} else {
+			first = i;
+		}
+	}
+
+	/*
+	 * Scan forward and stop for the first non-contiguous
+	 * entry or stop for a page being in buffer cache.
+	 */
+	failflag = 0;
+	last = reqpage + 1;
+	for (i = reqpage + 1; i < count; i++) {
+		if (failflag ||
+		   incore(vp, (foff + (i - reqpage) * PAGE_SIZE) / bsize) ||
+		   (vnode_pager_addr(vp, m[i]->offset + paging_offset))
+				!= reqaddr + (i - reqpage) * PAGE_SIZE) {
+			vnode_pager_freepage(m[i]);
+			failflag = 1;
+		} else {
+			last = i + 1;
+		}
+	}
+	splx(s);
+
+	/*
+	 * the first and last page have been calculated now, move input
+	 * pages to be zero based...
+	 */
+	count = last;
+	if (first != 0) {
+		for (i = first; i < count; i++) {
+			m[i - first] = m[i];
+		}
+		count -= first;
+		reqpage -= first;
 	}
-	if (foff + PAGE_SIZE > vnp->vnp_size)
+
+	/*
+	 * calculate the file virtual address for the transfer
+	 */
+	foff = m[0]->offset + paging_offset;
+	/*
+	 * and get the disk physical address (in bytes)
+	 */
+	firstaddr = vnode_pager_addr(vp, foff);
+
+	/*
+	 * calculate the size of the transfer
+	 */
+	size = count * PAGE_SIZE;
+	if ((foff + size) > vnp->vnp_size)
 		size = vnp->vnp_size - foff;
-	else
+
+	/*
+	 * round up physical size for real devices
+	 */
+	if( dp->v_type == VBLK || dp->v_type == VCHR)
+		size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
+
+	/*
+	 * and map the pages to be read into the kva
+	 */
+	for (i = 0; i < count; i++)
+		pmap_kenter( kva + PAGE_SIZE * i, VM_PAGE_TO_PHYS(m[i]));
+
+	pmap_update();
+	bp = getpbuf();
+	VHOLD(vp);
+
+	/* build a minimal buffer header */
+	bp->b_flags = B_BUSY | B_READ | B_CALL;
+	bp->b_iodone = vnode_pager_iodone;
+	/* B_PHYS is not set, but it is nice to fill this in */
+	bp->b_proc = curproc;
+	bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
+	if( bp->b_rcred != NOCRED)
+		crhold(bp->b_rcred);
+	if( bp->b_wcred != NOCRED)
+		crhold(bp->b_wcred);
+	bp->b_un.b_addr = (caddr_t) kva;
+	bp->b_blkno = firstaddr / DEV_BSIZE;
+	bgetvp(dp, bp);
+	bp->b_bcount = size;
+	bp->b_bufsize = size;
+
+	/* do the input */
+	VOP_STRATEGY(bp);
+
+	s = splbio();
+	/* we definitely need to be at splbio here */
+
+	while ((bp->b_flags & B_DONE) == 0) {
+		tsleep((caddr_t)bp, PVM, "vnread", 0);
+	}
+	splx(s);
+	if ((bp->b_flags & B_ERROR) != 0)
+		error = EIO;
+
+	if (!error) {
+		if (size != count * PAGE_SIZE)
+			bzero((caddr_t)kva + size, PAGE_SIZE * count - size);
+	}
+
+	pmap_remove(vm_map_pmap(pager_map), kva, kva + PAGE_SIZE * count);
+	kmem_free_wakeup(pager_map, kva, mapsize);
+
+	/*
+	 * free the buffer header back to the swap buffer pool
+	 */
+	relpbuf(bp);
+	HOLDRELE(vp);
+
+finishup:
+	for (i = 0; i < count; i++) {
+		pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
+		m[i]->flags |= PG_CLEAN;
+		m[i]->flags &= ~PG_LAUNDRY;
+		if (i != reqpage) {
+			/*
+			 * whether or not to leave the page activated
+			 * is up in the air, but we should put the page
+			 * on a page queue somewhere. (it already is in
+			 * the object).
+			 * Result: It appears that emperical results show
+			 * that deactivating pages is best.
+			 */
+			/*
+			 * just in case someone was asking for this
+			 * page we now tell them that it is ok to use
+			 */
+			if (!error) {
+				vm_page_deactivate(m[i]);
+				PAGE_WAKEUP(m[i]);
+				m[i]->flags &= ~PG_FAKE;
+				m[i]->act_count = 2;
+			} else {
+				vnode_pager_freepage(m[i]);
+			}
+		}
+	}
+	if (error) {
+		printf("vnode pager read error: %d\n", error);
+	}
+	if (errtype)
+		return error;
+	return (error ? VM_PAGER_FAIL : VM_PAGER_OK);
+}
+
+/*
+ * old-style vnode pager output routine
+ */
+int
+vnode_pager_output_old(vnp, m)
+	register vn_pager_t vnp;
+	vm_page_t m;
+{
+	vm_offset_t foff;
+	vm_offset_t kva;
+	vm_offset_t size;
+	struct iovec aiov;
+	struct uio auio;
+	struct vnode *vp;
+	int error;
+
+	vp = vnp->vnp_vp;
+	foff = m->offset + m->object->paging_offset;
+	/*
+	 * Return failure if beyond current EOF
+	 */
+	if (foff >= vnp->vnp_size) {
+		return VM_PAGER_BAD;
+	} else {
 		size = PAGE_SIZE;
-	aiov.iov_base = (caddr_t)kva;
-	aiov.iov_len = size;
-	auio.uio_iov = &aiov;
-	auio.uio_iovcnt = 1;
-	auio.uio_offset = foff;
-	auio.uio_segflg = UIO_SYSSPACE;
-	auio.uio_rw = rw;
-	auio.uio_resid = size;
-	auio.uio_procp = (struct proc *)0;
-#ifdef DEBUG
-	if (vpagerdebug & VDB_IO)
-		printf("vnode_pager_io: vp %x kva %x foff %x size %x",
-		       vnp->vnp_vp, kva, foff, size);
-#endif
-	if (rw == UIO_READ)
-		error = VOP_READ(vnp->vnp_vp, &auio, 0, p->p_ucred);
+		if (foff + size > vnp->vnp_size)
+			size = vnp->vnp_size - foff;
+/*
+ * Allocate a kernel virtual address and initialize so that
+ * we can use VOP_WRITE routines.
+ */
+		kva = vm_pager_map_page(m);
+		aiov.iov_base = (caddr_t)kva;
+		aiov.iov_len = size;
+		auio.uio_iov = &aiov;
+		auio.uio_iovcnt = 1;
+		auio.uio_offset = foff;
+		auio.uio_segflg = UIO_SYSSPACE;
+		auio.uio_rw = UIO_WRITE;
+		auio.uio_resid = size;
+		auio.uio_procp = (struct proc *)0;
+
+		error = VOP_WRITE(vp, &auio, 0, curproc->p_ucred);
+
+		if (!error) {
+			if ((size - auio.uio_resid) == 0) {
+				error = EINVAL;
+			}
+		}
+		vm_pager_unmap_page(kva);
+		return error?VM_PAGER_FAIL:VM_PAGER_OK;
+	}
+}
+
+/*
+ * vnode pager output on a small-block file system
+ */
+int
+vnode_pager_output_smlfs(vnp, m)
+	vn_pager_t vnp;
+	vm_page_t m;
+{
+	int i;
+	int s;
+	vm_offset_t paging_offset;
+	struct vnode *dp, *vp;
+	struct buf *bp;
+	vm_offset_t mapsize;
+	vm_offset_t foff;
+	vm_offset_t kva;
+	int fileaddr;
+	int block;
+	vm_offset_t bsize;
+	int run;
+	int error = 0;
+
+	paging_offset = m->object->paging_offset;
+	vp = vnp->vnp_vp;
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+	foff = m->offset + paging_offset;
+
+	VOP_BMAP(vp, foff, &dp, 0, 0);
+	kva = vm_pager_map_page(m);
+	for(i = 0; !error && i < (PAGE_SIZE/bsize); i++) {
+	/*
+	 * calculate logical block and offset
+	 */
+		fileaddr = vnode_pager_addr(vp, foff + i * bsize);
+		if( fileaddr != -1) {
+			s = splbio();
+			if( bp = incore( vp, (foff/bsize) + i)) {
+				bp = getblk(vp, (foff/bsize) + i, bp->b_bufsize,0, 0);
+				bp->b_flags |= B_INVAL;
+				brelse(bp);
+			}
+			splx(s);
+
+			bp = getpbuf();
+			VHOLD(vp);
+
+	/* build a minimal buffer header */
+			bp->b_flags = B_BUSY | B_CALL | B_WRITE;
+			bp->b_iodone = vnode_pager_iodone;
+			bp->b_proc = curproc;
+			bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
+			if( bp->b_rcred != NOCRED)
+				crhold(bp->b_rcred);
+			if( bp->b_wcred != NOCRED)
+				crhold(bp->b_wcred);
+			bp->b_un.b_addr = (caddr_t) kva + i * bsize;
+			bp->b_blkno = fileaddr / DEV_BSIZE;
+			bgetvp(dp, bp);
+			++dp->v_numoutput;
+	/* for NFS */
+			bp->b_dirtyoff = 0;
+			bp->b_dirtyend = bsize;
+			bp->b_bcount = bsize;
+			bp->b_bufsize = bsize;
+	
+	/* do the input */
+			VOP_STRATEGY(bp);
+
+	/* we definitely need to be at splbio here */
+
+			s = splbio();
+			while ((bp->b_flags & B_DONE) == 0) {
+				tsleep((caddr_t)bp, PVM, "vnswrt", 0);
+			}
+			splx(s);
+			if ((bp->b_flags & B_ERROR) != 0)
+				error = EIO;
+
+	/*
+	 * free the buffer header back to the swap buffer pool
+	 */
+			relpbuf(bp);
+			HOLDRELE(vp);
+		} 
+	}
+	vm_pager_unmap_page(kva);
+	if( error)
+		return VM_PAGER_FAIL;
 	else
-		error = VOP_WRITE(vnp->vnp_vp, &auio, 0, p->p_ucred);
-	VOP_UNLOCK(vnp->vnp_vp);
-#ifdef DEBUG
-	if (vpagerdebug & VDB_IO) {
-		if (error || auio.uio_resid)
-			printf(" returns error %x, resid %x",
-			       error, auio.uio_resid);
-		printf("\n");
+		return VM_PAGER_OK;
+}
+
+/*
+ * generic vnode pager output routine
+ */
+int
+vnode_pager_output(vnp, m, count, rtvals)
+	vn_pager_t vnp;
+	vm_page_t *m;
+	int count;
+	int *rtvals;
+{
+	int i,j;
+	vm_offset_t kva, foff;
+	int size;
+	struct proc *p = curproc;		/* XXX */
+	vm_object_t object;
+	vm_offset_t paging_offset;
+	struct vnode *dp, *vp;
+	struct buf *bp;
+	vm_offset_t mapsize;
+	vm_offset_t reqaddr;
+	int run;
+	int bsize;
+	int s;
+
+	int error = 0;
+
+retryoutput:
+	object = m[0]->object;	/* all vm_page_t items are in same object */
+	paging_offset = object->paging_offset;
+
+	vp = vnp->vnp_vp;
+	bsize = vp->v_mount->mnt_stat.f_iosize;
+
+	for(i=0;i<count;i++)
+		rtvals[i] = VM_PAGER_AGAIN;
+
+	/*
+	 * if the filesystem does not have a bmap, then use the
+	 * old code
+	 */
+	if (VOP_BMAP(vp, m[0]->offset+paging_offset, &dp, 0, 0)) {
+
+		rtvals[0] = vnode_pager_output_old(vnp, m[0]);
+
+		pmap_clear_modify(VM_PAGE_TO_PHYS(m[0]));
+		m[0]->flags |= PG_CLEAN;
+		m[0]->flags &= ~PG_LAUNDRY;
+		return rtvals[0];
 	}
-#endif
-	if (!error) {
-		register int count = size - auio.uio_resid;
 
-		if (count == 0)
-			error = EINVAL;
-		else if (count != PAGE_SIZE && rw == UIO_READ)
-			bzero((void *)(kva + count), PAGE_SIZE - count);
+	/*
+	 * if the filesystem has a small blocksize, then use
+	 * the small block filesystem output code
+	 */
+	if ((bsize < PAGE_SIZE) &&
+		(vp->v_mount->mnt_stat.f_type != MOUNT_NFS)) {
+
+		for(i=0;i<count;i++) {
+			rtvals[i] = vnode_pager_output_smlfs(vnp, m[i]);
+			if( rtvals[i] == VM_PAGER_OK) {
+				pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
+				m[i]->flags |= PG_CLEAN;
+				m[i]->flags &= ~PG_LAUNDRY;
+			}
+		}
+		return rtvals[0];
 	}
-	vm_pager_unmap_pages(kva, npages);
-	return (error ? VM_PAGER_ERROR : VM_PAGER_OK);
+
+	/*
+	 * get some kva for the output
+	 */
+	kva = kmem_alloc_pageable(pager_map, (mapsize = count*PAGE_SIZE));
+	if( !kva) {
+		kva = kmem_alloc_pageable(pager_map, (mapsize = PAGE_SIZE));
+		count = 1;
+		if( !kva)
+			return rtvals[0];
+	}
+
+	for(i=0;i<count;i++) {
+		foff = m[i]->offset + paging_offset;
+		if (foff >= vnp->vnp_size) {
+			for(j=i;j<count;j++)
+				rtvals[j] = VM_PAGER_BAD;
+			count = i;
+			break;
+		}
+	}
+	if (count == 0) {
+		return rtvals[0];
+	}
+	foff = m[0]->offset + paging_offset;
+	reqaddr = vnode_pager_addr(vp, foff);
+	/*
+	 * Scan forward and stop for the first non-contiguous
+	 * entry or stop for a page being in buffer cache.
+	 */
+	for (i = 1; i < count; i++) {
+		if ( vnode_pager_addr(vp, m[i]->offset + paging_offset)
+			!= reqaddr + i * PAGE_SIZE) {
+			count = i;
+			break;
+		}
+	}
+
+	/*
+	 * calculate the size of the transfer
+	 */
+	size = count * PAGE_SIZE;
+	if ((foff + size) > vnp->vnp_size)
+		size = vnp->vnp_size - foff;
+
+	/*
+	 * round up physical size for real devices
+	 */
+	if( dp->v_type == VBLK || dp->v_type == VCHR)
+		size = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1);
+
+	/*
+	 * and map the pages to be read into the kva
+	 */
+	for (i = 0; i < count; i++)
+		pmap_kenter( kva + PAGE_SIZE * i, VM_PAGE_TO_PHYS(m[i]));
+	pmap_update();
+/*
+	printf("vnode: writing foff: %d, devoff: %d, size: %d\n",
+		foff, reqaddr, size);
+*/
+	/*
+	 * next invalidate the incore vfs_bio data
+	 */
+	for (i = 0; i < count; i++) {
+		int filblock = (foff + i * PAGE_SIZE) / bsize;
+		struct buf *fbp;
+
+		s = splbio();
+		if( fbp = incore( vp, filblock)) {
+			/* printf("invalidating: %d\n", filblock); */
+			fbp = getblk(vp, filblock, fbp->b_bufsize,0,0);
+			fbp->b_flags |= B_INVAL;
+			brelse(fbp);
+		}
+		splx(s);
+	}
+
+
+	bp = getpbuf();
+	VHOLD(vp);
+	/* build a minimal buffer header */
+	bp->b_flags = B_BUSY | B_WRITE | B_CALL;
+	bp->b_iodone = vnode_pager_iodone;
+	/* B_PHYS is not set, but it is nice to fill this in */
+	bp->b_proc = curproc;
+	bp->b_rcred = bp->b_wcred = bp->b_proc->p_ucred;
+
+	if( bp->b_rcred != NOCRED)
+		crhold(bp->b_rcred);
+	if( bp->b_wcred != NOCRED)
+		crhold(bp->b_wcred);
+	bp->b_un.b_addr = (caddr_t) kva;
+	bp->b_blkno = reqaddr / DEV_BSIZE;
+	bgetvp(dp, bp);
+	++dp->v_numoutput;
+	
+	/* for NFS */
+	bp->b_dirtyoff = 0;
+	bp->b_dirtyend = size;
+
+	bp->b_bcount = size;
+	bp->b_bufsize = size;
+
+	/* do the output */
+	VOP_STRATEGY(bp);
+
+	s = splbio();
+
+	/* we definitely need to be at splbio here */
+
+	while ((bp->b_flags & B_DONE) == 0) {
+		tsleep((caddr_t)bp, PVM, "vnwrite", 0);
+	}
+	splx(s);
+
+	if ((bp->b_flags & B_ERROR) != 0)
+		error = EIO;
+
+	pmap_remove(vm_map_pmap(pager_map), kva, kva + PAGE_SIZE * count);
+	kmem_free_wakeup(pager_map, kva, mapsize);
+
+	/*
+	 * free the buffer header back to the swap buffer pool
+	 */
+	relpbuf(bp);
+	HOLDRELE(vp);
+
+	if( !error) {
+		for(i=0;i<count;i++) {
+			pmap_clear_modify(VM_PAGE_TO_PHYS(m[i]));
+			m[i]->flags |= PG_CLEAN;
+			m[i]->flags &= ~PG_LAUNDRY;
+			rtvals[i] = VM_PAGER_OK;
+		}
+	} else if( count != 1) {
+		error = 0;
+		count = 1;
+		goto retryoutput;
+	}
+		
+	if (error) {
+		printf("vnode pager write error: %d\n", error);
+	}
+	return (error ? VM_PAGER_FAIL : VM_PAGER_OK);
 }
+