1 files changed, 264 insertions, 387 deletions

diff --git a/sys/kern/vfs_cluster.c b/sys/kern/vfs_cluster.c
index e58dfc178d29..bca74820a785 100644
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@@ -1,6 +1,8 @@
 /*-
  * Copyright (c) 1993
  *	The Regents of the University of California.  All rights reserved.
+ * Modifications/enhancements:
+ * 	Copyright (c) 1995 John S. Dyson.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,7 +33,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)vfs_cluster.c	8.7 (Berkeley) 2/13/94
- * $Id: vfs_cluster.c,v 1.6 1994/10/08 22:33:41 phk Exp $
+ * $Id: vfs_cluster.c,v 1.7 1994/12/18 03:05:49 davidg Exp $
  */
 
 #include <sys/param.h>
@@ -43,12 +45,15 @@
 #include <sys/trace.h>
 #include <sys/malloc.h>
 #include <sys/resourcevar.h>
+#include <sys/vmmeter.h>
+#include <miscfs/specfs/specdev.h>
 
 #ifdef DEBUG
 #include <vm/vm.h>
 #include <sys/sysctl.h>
 int doreallocblks = 0;
-struct ctldebug debug13 = { "doreallocblks", &doreallocblks };
+struct ctldebug debug13 = {"doreallocblks", &doreallocblks};
+
 #else
 /* XXX for cluster_write */
 #define doreallocblks 0
@@ -57,14 +62,14 @@ struct ctldebug debug13 = { "doreallocblks", &doreallocblks };
 /*
  * Local declarations
  */
-struct buf *cluster_newbuf __P((struct vnode *, struct buf *, long, daddr_t,
-	    daddr_t, long, int));
 struct buf *cluster_rbuild __P((struct vnode *, u_quad_t, struct buf *,
-	    daddr_t, daddr_t, long, int, long));
-void	    cluster_wbuild __P((struct vnode *, struct buf *, long,
-	    daddr_t, int, daddr_t));
+    daddr_t, daddr_t, long, int, long));
+void cluster_wbuild __P((struct vnode *, struct buf *, long, daddr_t, int, daddr_t));
 struct cluster_save *cluster_collectbufs __P((struct vnode *, struct buf *));
 
+int totreads;
+int totreadblocks;
+
 #ifdef DIAGNOSTIC
 /*
  * Set to 1 if reads of block zero should cause readahead to be done.
@@ -78,7 +83,8 @@ struct cluster_save *cluster_collectbufs __P((struct vnode *, struct buf *));
  * blocks from the cache.  The former seems intuitive, but some quick tests
  * showed that the latter performed better from a system-wide point of view.
  */
-int	doclusterraz = 0;
+	int doclusterraz = 0;
+
 #define ISSEQREAD(vp, blk) \
 	(((blk) != 0 || doclusterraz) && \
 	 ((blk) == (vp)->v_lastr + 1 || (blk) == (vp)->v_lastr))
@@ -92,17 +98,6 @@ int	doclusterraz = 0;
  * lastr is 0, we assume this is the first read and we'll read up to two
  * blocks if they are sequential.  After that, we'll do regular read ahead
  * in clustered chunks.
- *
- * There are 4 or 5 cases depending on how you count:
- *	Desired block is in the cache:
- *	    1 Not sequential access (0 I/Os).
- *	    2 Access is sequential, do read-ahead (1 ASYNC).
- *	Desired block is not in cache:
- *	    3 Not sequential access (1 SYNC).
- *	    4 Sequential access, next block is contiguous (1 SYNC).
- *	    5 Sequential access, next block is not contiguous (1 SYNC, 1 ASYNC)
- *
- * There are potentially two buffers that require I/O.
  * 	bp is the block requested.
  *	rbp is the read-ahead block.
  *	If either is NULL, then you don't have to do the I/O.
@@ -117,156 +112,136 @@ cluster_read(vp, filesize, lblkno, size, cred, bpp)
 	struct buf **bpp;
 {
 	struct buf *bp, *rbp;
-	daddr_t blkno, ioblkno;
+	daddr_t blkno, rablkno, origlblkno;
 	long flags;
 	int error, num_ra, alreadyincore;
 
-#ifdef DIAGNOSTIC
-	if (size == 0)
-		panic("cluster_read: size = 0");
-#endif
-
+	origlblkno = lblkno;
 	error = 0;
-	flags = B_READ;
+	/*
+	 * get the requested block
+	 */
 	*bpp = bp = getblk(vp, lblkno, size, 0, 0);
+	/*
+	 * if it is in the cache, then check to see if the reads have been
+	 * sequential.  If they have, then try some read-ahead, otherwise
+	 * back-off on prospective read-aheads.
+	 */
 	if (bp->b_flags & B_CACHE) {
-		/*
-		 * Desired block is in cache; do any readahead ASYNC.
-		 * Case 1, 2.
-		 */
-		trace(TR_BREADHIT, pack(vp, size), lblkno);
-		flags |= B_ASYNC;
-		ioblkno = lblkno + (vp->v_ralen ? vp->v_ralen : 1);
-		alreadyincore = (int)incore(vp, ioblkno);
+		int i;
+
+		if (!ISSEQREAD(vp, origlblkno)) {
+			vp->v_ralen >>= 1;
+			return 0;
+		}
 		bp = NULL;
 	} else {
-		/* Block wasn't in cache, case 3, 4, 5. */
-		trace(TR_BREADMISS, pack(vp, size), lblkno);
+		/*
+		 * if it isn't in the cache, then get a chunk from disk if
+		 * sequential, otherwise just get the block.
+		 */
 		bp->b_flags |= B_READ;
-		ioblkno = lblkno;
-		alreadyincore = 0;
-		curproc->p_stats->p_ru.ru_inblock++;		/* XXX */
+		lblkno += 1;
+		curproc->p_stats->p_ru.ru_inblock++;	/* XXX */
 	}
 	/*
-	 * XXX
-	 * Replace 1 with a window size based on some permutation of
-	 * maxcontig and rot_delay.  This will let you figure out how
-	 * many blocks you should read-ahead (case 2, 4, 5).
-	 *
-	 * If the access isn't sequential, reset the window to 1.
-	 * Note that a read to the same block is considered sequential.
-	 * This catches the case where the file is being read sequentially,
-	 * but at smaller than the filesystem block size.
+	 * if ralen is "none", then try a little
 	 */
-	rbp = NULL;
-	if (!ISSEQREAD(vp, lblkno)) {
-		vp->v_ralen = 0;
-		vp->v_maxra = lblkno;
-	} else if ((ioblkno + 1) * size <= filesize && !alreadyincore &&
-	    !(error = VOP_BMAP(vp, ioblkno, NULL, &blkno, &num_ra)) &&
-	    blkno != -1) {
+	if (vp->v_ralen == 0)
+		vp->v_ralen = 1;
+	/*
+	 * assume no read-ahead
+	 */
+	alreadyincore = 1;
+	rablkno = lblkno;
+
+	/*
+	 * if we have been doing sequential I/O, then do some read-ahead
+	 */
+	if (ISSEQREAD(vp, origlblkno)) {
+		int i;
+
 		/*
-		 * Reading sequentially, and the next block is not in the
-		 * cache.  We are going to try reading ahead.
+		 * this code makes sure that the stuff that we have read-ahead
+		 * is still in the cache.  If it isn't, we have been reading
+		 * ahead too much, and we need to back-off, otherwise we might
+		 * try to read more.
 		 */
-		if (num_ra) {
-			/*
-			 * If our desired readahead block had been read
-			 * in a previous readahead but is no longer in
-			 * core, then we may be reading ahead too far
-			 * or are not using our readahead very rapidly.
-			 * In this case we scale back the window.
-			 */
-			if (!alreadyincore && ioblkno <= vp->v_maxra)
-				vp->v_ralen = max(vp->v_ralen >> 1, 1);
-			/*
-			 * There are more sequential blocks than our current
-			 * window allows, scale up.  Ideally we want to get
-			 * in sync with the filesystem maxcontig value.
-			 */
-			else if (num_ra > vp->v_ralen && lblkno != vp->v_lastr)
-				vp->v_ralen = vp->v_ralen ?
-					min(num_ra, vp->v_ralen << 1) : 1;
-
-			if (num_ra > vp->v_ralen)
-				num_ra = vp->v_ralen;
+		for (i = 0; i < vp->v_ralen; i++) {
+			rablkno = lblkno + i;
+			alreadyincore = (int) incore(vp, rablkno);
+			if (!alreadyincore) {
+				if (rablkno < vp->v_maxra) {
+					vp->v_maxra = rablkno;
+					vp->v_ralen >>= 1;
+					alreadyincore = 1;
+				} else {
+					if (inmem(vp, rablkno))
+						continue;
+					if ((vp->v_ralen + 1) < MAXPHYS / size)
+						vp->v_ralen++;
+				}
+				break;
+			}
 		}
+	}
+	/*
+	 * we now build the read-ahead buffer if it is desirable.
+	 */
+	rbp = NULL;
+	if (!alreadyincore &&
+	    (rablkno + 1) * size <= filesize &&
+	    !(error = VOP_BMAP(vp, rablkno, NULL, &blkno, &num_ra)) &&
+	    blkno != -1) {
+		if (num_ra > vp->v_ralen)
+			num_ra = vp->v_ralen;
 
-		if (num_ra)				/* case 2, 4 */
+		if (num_ra &&
+		    ((cnt.v_free_count + cnt.v_cache_count) > cnt.v_free_reserved)) {
 			rbp = cluster_rbuild(vp, filesize,
-			    bp, ioblkno, blkno, size, num_ra, flags);
-		else if (ioblkno == lblkno) {
-			bp->b_blkno = blkno;
-			/* Case 5: check how many blocks to read ahead */
-			++ioblkno;
-			if ((ioblkno + 1) * size > filesize ||
-			    incore(vp, ioblkno) || (error = VOP_BMAP(vp,
-			     ioblkno, NULL, &blkno, &num_ra)) || blkno == -1)
-				goto skip_readahead;
-			/*
-			 * Adjust readahead as above
-			 */
-			if (num_ra) {
-				if (!alreadyincore && ioblkno <= vp->v_maxra)
-					vp->v_ralen = max(vp->v_ralen >> 1, 1);
-				else if (num_ra > vp->v_ralen &&
-					 lblkno != vp->v_lastr)
-					vp->v_ralen = vp->v_ralen ?
-						min(num_ra,vp->v_ralen<<1) : 1;
-				if (num_ra > vp->v_ralen)
-					num_ra = vp->v_ralen;
-			}
-			flags |= B_ASYNC;
-			if (num_ra)
-				rbp = cluster_rbuild(vp, filesize,
-				    NULL, ioblkno, blkno, size, num_ra, flags);
-			else {
-				rbp = getblk(vp, ioblkno, size, 0, 0);
-				rbp->b_flags |= flags;
-				rbp->b_blkno = blkno;
-			}
+			    NULL, rablkno, blkno, size, num_ra, B_READ | B_ASYNC);
 		} else {
-			/* case 2; read ahead single block */
-			rbp = getblk(vp, ioblkno, size, 0, 0);
-			rbp->b_flags |= flags;
+			rbp = getblk(vp, rablkno, size, 0, 0);
+			rbp->b_flags |= B_READ | B_ASYNC;
 			rbp->b_blkno = blkno;
 		}
-
-		if (rbp == bp)			/* case 4 */
-			rbp = NULL;
-		else if (rbp) {			/* case 2, 5 */
-			trace(TR_BREADMISSRA,
-			    pack(vp, (num_ra + 1) * size), ioblkno);
-			curproc->p_stats->p_ru.ru_inblock++;	/* XXX */
-		}
 	}
-
-	/* XXX Kirk, do we need to make sure the bp has creds? */
 skip_readahead:
-	if (bp)
+	/*
+	 * if the synchronous read is a cluster, handle it, otherwise do a
+	 * simple, non-clustered read.
+	 */
+	if (bp) {
 		if (bp->b_flags & (B_DONE | B_DELWRI))
 			panic("cluster_read: DONE bp");
-		else 
+		else {
+			vfs_busy_pages(bp, 0);
 			error = VOP_STRATEGY(bp);
-
-	if (rbp)
-		if (error || rbp->b_flags & (B_DONE | B_DELWRI)) {
+			vp->v_maxra = bp->b_lblkno + bp->b_bcount / size;
+			totreads++;
+			totreadblocks += bp->b_bcount / size;
+			curproc->p_stats->p_ru.ru_inblock++;
+		}
+	}
+	/*
+	 * and if we have read-aheads, do them too
+	 */
+	if (rbp) {
+		if (error || (rbp->b_flags & B_CACHE)) {
 			rbp->b_flags &= ~(B_ASYNC | B_READ);
 			brelse(rbp);
-		} else
+		} else {
+			vfs_busy_pages(rbp, 0);
 			(void) VOP_STRATEGY(rbp);
-
-	/*
-	 * Recalculate our maximum readahead
-	 */
-	if (rbp == NULL)
-		rbp = bp;
-	if (rbp)
-		vp->v_maxra = rbp->b_lblkno + (rbp->b_bufsize / size) - 1;
-
+			vp->v_maxra = rbp->b_lblkno + rbp->b_bcount / size;
+			totreads++;
+			totreadblocks += rbp->b_bcount / size;
+			curproc->p_stats->p_ru.ru_inblock++;
+		}
+	}
 	if (bp)
-		return(biowait(bp));
-	return(error);
+		return (biowait(bp));
+	return (error);
 }
 
 /*
@@ -288,12 +263,12 @@ cluster_rbuild(vp, filesize, bp, lbn, blkno, size, run, flags)
 	struct cluster_save *b_save;
 	struct buf *tbp;
 	daddr_t bn;
-	int i, inc;
+	int i, inc, j;
 
 #ifdef DIAGNOSTIC
 	if (size != vp->v_mount->mnt_stat.f_iosize)
 		panic("cluster_rbuild: size %d != filesize %d\n",
-			size, vp->v_mount->mnt_stat.f_iosize);
+		    size, vp->v_mount->mnt_stat.f_iosize);
 #endif
 	if (size * (lbn + run + 1) > filesize)
 		--run;
@@ -303,97 +278,65 @@ cluster_rbuild(vp, filesize, bp, lbn, blkno, size, run, flags)
 			bp->b_blkno = blkno;
 			bp->b_flags |= flags;
 		}
-		return(bp);
-	}
-
-	bp = cluster_newbuf(vp, bp, flags, blkno, lbn, size, run + 1);
-	if (bp->b_flags & (B_DONE | B_DELWRI))
 		return (bp);
+	}
+	tbp = bp;
+	if (!tbp) {
+		tbp = getblk(vp, lbn, size, 0, 0);
+	}
+	if (tbp->b_flags & B_CACHE) {
+		return (tbp);
+	} else if (bp == NULL) {
+		tbp->b_flags |= B_ASYNC;
+	}
+	bp = getpbuf();
+	bp->b_flags = flags | B_CALL | B_BUSY | B_CLUSTER;
+	bp->b_iodone = cluster_callback;
+	bp->b_blkno = blkno;
+	bp->b_lblkno = lbn;
+	pbgetvp(vp, bp);
 
 	b_save = malloc(sizeof(struct buf *) * (run + 1) + sizeof(struct cluster_save),
 	    M_SEGMENT, M_WAITOK);
-	b_save->bs_bufsize = b_save->bs_bcount = size;
 	b_save->bs_nchildren = 0;
-	b_save->bs_children = (struct buf **)(b_save + 1);
-	b_save->bs_saveaddr = bp->b_saveaddr;
-	bp->b_saveaddr = (caddr_t) b_save;
+	b_save->bs_children = (struct buf **) (b_save + 1);
+	bp->b_saveaddr = b_save;
+
+	bp->b_bcount = 0;
+	bp->b_bufsize = 0;
+	bp->b_npages = 0;
+
+	if (tbp->b_flags & B_VMIO)
+		bp->b_flags |= B_VMIO;
 
 	inc = btodb(size);
-	for (bn = blkno + inc, i = 1; i <= run; ++i, bn += inc) {
-		if (incore(vp, lbn + i)) {
-			if (i == 1) {
-				bp->b_saveaddr = b_save->bs_saveaddr;
-				bp->b_flags &= ~B_CALL;
-				bp->b_iodone = NULL;
-				allocbuf(bp, size);
-				free(b_save, M_SEGMENT);
-			} else
-				allocbuf(bp, size * i);
-			break;
-		}
-		tbp = getblk(vp, lbn + i, 0, 0, 0);
-		/*
-		 * getblk may return some memory in the buffer if there were
-		 * no empty buffers to shed it to.  If there is currently
-		 * memory in the buffer, we move it down size bytes to make
-		 * room for the valid pages that cluster_callback will insert.
-		 * We do this now so we don't have to do it at interrupt time
-		 * in the callback routine.
-		 */
-		if (tbp->b_bufsize != 0) {
-			caddr_t bdata = (char *)tbp->b_data;
-
-			if (tbp->b_bufsize + size > MAXBSIZE)
-				panic("cluster_rbuild: too much memory");
-			if (tbp->b_bufsize > size) {
-				/*
-				 * XXX if the source and destination regions
-				 * overlap we have to copy backward to avoid
-				 * clobbering any valid pages (i.e. pagemove
-				 * implementations typically can't handle
-				 * overlap).
-				 */
-				bdata += tbp->b_bufsize;
-				while (bdata > (char *)tbp->b_data) {
-					bdata -= CLBYTES;
-					pagemove(bdata, bdata + size, CLBYTES);
-				}
-			} else 
-				pagemove(bdata, bdata + size, tbp->b_bufsize);
+	for (bn = blkno, i = 0; i <= run; ++i, bn += inc) {
+		if (i != 0) {
+			if (inmem(vp, lbn + i)) {
+				break;
+			}
+			tbp = getblk(vp, lbn + i, size, 0, 0);
+			if ((tbp->b_flags & B_CACHE) ||
+			    (tbp->b_flags & B_VMIO) != (bp->b_flags & B_VMIO)) {
+				brelse(tbp);
+				break;
+			}
+			tbp->b_blkno = bn;
+			tbp->b_flags |= flags | B_READ | B_ASYNC;
+		} else {
+			tbp->b_flags |= flags | B_READ;
 		}
-		tbp->b_blkno = bn;
-		tbp->b_flags |= flags | B_READ | B_ASYNC;
 		++b_save->bs_nchildren;
-		b_save->bs_children[i - 1] = tbp;
-	}
-	return(bp);
-}
-
-/*
- * Either get a new buffer or grow the existing one.
- */
-struct buf *
-cluster_newbuf(vp, bp, flags, blkno, lblkno, size, run)
-	struct vnode *vp;
-	struct buf *bp;
-	long flags;
-	daddr_t blkno;
-	daddr_t lblkno;
-	long size;
-	int run;
-{
-	if (!bp) {
-		bp = getblk(vp, lblkno, size, 0, 0);
-		if (bp->b_flags & (B_DONE | B_DELWRI)) {
-			bp->b_blkno = blkno;
-			return(bp);
+		b_save->bs_children[i] = tbp;
+		for (j = 0; j < tbp->b_npages; j += 1) {
+			bp->b_pages[j + bp->b_npages] = tbp->b_pages[j];
 		}
+		bp->b_npages += tbp->b_npages;
+		bp->b_bcount += size;
+		bp->b_bufsize += size;
 	}
-	allocbuf(bp, run * size);
-	bp->b_blkno = blkno;
-	bp->b_iodone = cluster_callback;
-	bp->b_flags |= flags | B_CALL;
-	return(bp);
+	pmap_qenter(bp->b_data, bp->b_pages, bp->b_npages);
+	return (bp);
 }
 
 /*
@@ -408,7 +351,6 @@ cluster_callback(bp)
 {
 	struct cluster_save *b_save;
 	struct buf **bpp, *tbp;
-	long bsize;
 	caddr_t cp;
 	int error = 0;
 
@@ -418,46 +360,22 @@ cluster_callback(bp)
 	if (bp->b_flags & B_ERROR)
 		error = bp->b_error;
 
-	b_save = (struct cluster_save *)(bp->b_saveaddr);
-	bp->b_saveaddr = b_save->bs_saveaddr;
-
-	bsize = b_save->bs_bufsize;
-	cp = (char *)bp->b_data + bsize;
+	b_save = (struct cluster_save *) (bp->b_saveaddr);
+	pmap_qremove(bp->b_data, bp->b_npages);
 	/*
 	 * Move memory from the large cluster buffer into the component
 	 * buffers and mark IO as done on these.
 	 */
 	for (bpp = b_save->bs_children; b_save->bs_nchildren--; ++bpp) {
 		tbp = *bpp;
-		pagemove(cp, tbp->b_data, bsize);
-		tbp->b_bufsize += bsize;
-		tbp->b_bcount = bsize;
 		if (error) {
 			tbp->b_flags |= B_ERROR;
 			tbp->b_error = error;
 		}
 		biodone(tbp);
-		bp->b_bufsize -= bsize;
-		cp += bsize;
-	}
-	/*
-	 * If there was excess memory in the cluster buffer,
-	 * slide it up adjacent to the remaining valid data.
-	 */
-	if (bp->b_bufsize != bsize) {
-		if (bp->b_bufsize < bsize)
-			panic("cluster_callback: too little memory");
-		pagemove(cp, (char *)bp->b_data + bsize, bp->b_bufsize - bsize);
 	}
-	bp->b_bcount = bsize;
-	bp->b_iodone = NULL;
 	free(b_save, M_SEGMENT);
-	if (bp->b_flags & B_ASYNC)
-		brelse(bp);
-	else {
-		bp->b_flags &= ~B_WANTED;
-		wakeup((caddr_t)bp);
-	}
+	relpbuf(bp);
 }
 
 /*
@@ -472,78 +390,47 @@ cluster_callback(bp)
  */
 void
 cluster_write(bp, filesize)
-        struct buf *bp;
+	struct buf *bp;
 	u_quad_t filesize;
 {
-        struct vnode *vp;
-        daddr_t lbn;
-        int maxclen, cursize;
+	struct vnode *vp;
+	daddr_t lbn;
+	int maxclen, cursize;
+	int lblocksize;
 
-        vp = bp->b_vp;
-        lbn = bp->b_lblkno;
+	vp = bp->b_vp;
+	lblocksize = vp->v_mount->mnt_stat.f_iosize;
+	lbn = bp->b_lblkno;
 
 	/* Initialize vnode to beginning of file. */
 	if (lbn == 0)
 		vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
 
-        if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
-	    (bp->b_blkno != vp->v_lasta + btodb(bp->b_bcount))) {
-		maxclen = MAXBSIZE / vp->v_mount->mnt_stat.f_iosize - 1;
+	if (vp->v_clen == 0 || lbn != vp->v_lastw + 1 ||
+	    (bp->b_blkno != vp->v_lasta + btodb(lblocksize))) {
+		maxclen = MAXPHYS / lblocksize;
 		if (vp->v_clen != 0) {
 			/*
 			 * Next block is not sequential.
-			 *
+			 * 
 			 * If we are not writing at end of file, the process
-			 * seeked to another point in the file since its
-			 * last write, or we have reached our maximum
-			 * cluster size, then push the previous cluster.
-			 * Otherwise try reallocating to make it sequential.
+			 * seeked to another point in the file since its last
+			 * write, or we have reached our maximum cluster size,
+			 * then push the previous cluster. Otherwise try
+			 * reallocating to make it sequential.
 			 */
 			cursize = vp->v_lastw - vp->v_cstart + 1;
-			if (!doreallocblks ||
-			    (lbn + 1) * bp->b_bcount != filesize ||
-			    lbn != vp->v_lastw + 1 || vp->v_clen <= cursize) {
-				cluster_wbuild(vp, NULL, bp->b_bcount,
-				    vp->v_cstart, cursize, lbn);
-			} else {
-				struct buf **bpp, **endbp;
-				struct cluster_save *buflist;
-
-				buflist = cluster_collectbufs(vp, bp);
-				endbp = &buflist->bs_children
-				    [buflist->bs_nchildren - 1];
-				if (VOP_REALLOCBLKS(vp, buflist)) {
-					/*
-					 * Failed, push the previous cluster.
-					 */
-					for (bpp = buflist->bs_children;
-					     bpp < endbp; bpp++)
-						brelse(*bpp);
-					free(buflist, M_SEGMENT);
-					cluster_wbuild(vp, NULL, bp->b_bcount,
-					    vp->v_cstart, cursize, lbn);
-				} else {
-					/*
-					 * Succeeded, keep building cluster.
-					 */
-					for (bpp = buflist->bs_children;
-					     bpp <= endbp; bpp++)
-						bdwrite(*bpp);
-					free(buflist, M_SEGMENT);
-					vp->v_lastw = lbn;
-					vp->v_lasta = bp->b_blkno;
-					return;
-				}
-			}
+			cluster_wbuild(vp, NULL, lblocksize,
+			    vp->v_cstart, cursize, lbn);
 		}
 		/*
-		 * Consider beginning a cluster.
-		 * If at end of file, make cluster as large as possible,
-		 * otherwise find size of existing cluster.
+		 * Consider beginning a cluster. If at end of file, make
+		 * cluster as large as possible, otherwise find size of
+		 * existing cluster.
 		 */
-		if ((lbn + 1) * bp->b_bcount != filesize &&
+		if ((lbn + 1) * lblocksize != filesize &&
 		    (VOP_BMAP(vp, lbn, NULL, &bp->b_blkno, &maxclen) ||
-		     bp->b_blkno == -1)) {
+			bp->b_blkno == -1)) {
 			bawrite(bp);
 			vp->v_clen = 0;
 			vp->v_lasta = bp->b_blkno;
@@ -551,13 +438,13 @@ cluster_write(bp, filesize)
 			vp->v_lastw = lbn;
 			return;
 		}
-                vp->v_clen = maxclen;
-                if (maxclen == 0) {		/* I/O not contiguous */
+		vp->v_clen = maxclen;
+		if (maxclen == 0) {	/* I/O not contiguous */
 			vp->v_cstart = lbn + 1;
-                        bawrite(bp);
-                } else {			/* Wait for rest of cluster */
+			bawrite(bp);
+		} else {	/* Wait for rest of cluster */
 			vp->v_cstart = lbn;
-                        bdwrite(bp);
+			bdwrite(bp);
 		}
 	} else if (lbn == vp->v_cstart + vp->v_clen) {
 		/*
@@ -569,8 +456,7 @@ cluster_write(bp, filesize)
 		vp->v_cstart = lbn + 1;
 	} else
 		/*
-		 * In the middle of a cluster, so just delay the
-		 * I/O for now.
+		 * In the middle of a cluster, so just delay the I/O for now.
 		 */
 		bdwrite(bp);
 	vp->v_lastw = lbn;
@@ -591,17 +477,17 @@ cluster_wbuild(vp, last_bp, size, start_lbn, len, lbn)
 	long size;
 	daddr_t start_lbn;
 	int len;
-	daddr_t	lbn;
+	daddr_t lbn;
 {
 	struct cluster_save *b_save;
 	struct buf *bp, *tbp;
-	caddr_t	cp;
-	int i, s;
+	caddr_t cp;
+	int i, j, s;
 
 #ifdef DIAGNOSTIC
 	if (size != vp->v_mount->mnt_stat.f_iosize)
 		panic("cluster_wbuild: size %d != filesize %d\n",
-			size, vp->v_mount->mnt_stat.f_iosize);
+		    size, vp->v_mount->mnt_stat.f_iosize);
 #endif
 redo:
 	while ((!incore(vp, start_lbn) || start_lbn == lbn) && len) {
@@ -619,104 +505,95 @@ redo:
 		}
 		return;
 	}
-
-	bp = getblk(vp, start_lbn, size, 0, 0);
-	if (!(bp->b_flags & B_DELWRI)) {
+	tbp = getblk(vp, start_lbn, size, 0, 0);
+	if (!(tbp->b_flags & B_DELWRI)) {
 		++start_lbn;
 		--len;
-		brelse(bp);
+		brelse(tbp);
 		goto redo;
 	}
-
 	/*
-	 * Extra memory in the buffer, punt on this buffer.
-	 * XXX we could handle this in most cases, but we would have to
-	 * push the extra memory down to after our max possible cluster
-	 * size and then potentially pull it back up if the cluster was
-	 * terminated prematurely--too much hassle.
+	 * Extra memory in the buffer, punt on this buffer. XXX we could
+	 * handle this in most cases, but we would have to push the extra
+	 * memory down to after our max possible cluster size and then
+	 * potentially pull it back up if the cluster was terminated
+	 * prematurely--too much hassle.
 	 */
-	if (bp->b_bcount != bp->b_bufsize) {
+	if (tbp->b_bcount != tbp->b_bufsize) {
 		++start_lbn;
 		--len;
-		bawrite(bp);
+		bawrite(tbp);
 		goto redo;
 	}
-
-	--len;
-	b_save = malloc(sizeof(struct buf *) * len + sizeof(struct cluster_save),
+	bp = getpbuf();
+	b_save = malloc(sizeof(struct buf *) * (len + 1) + sizeof(struct cluster_save),
 	    M_SEGMENT, M_WAITOK);
-	b_save->bs_bcount = bp->b_bcount;
-	b_save->bs_bufsize = bp->b_bufsize;
 	b_save->bs_nchildren = 0;
-	b_save->bs_children = (struct buf **)(b_save + 1);
-	b_save->bs_saveaddr = bp->b_saveaddr;
-	bp->b_saveaddr = (caddr_t) b_save;
-
-	bp->b_flags |= B_CALL;
+	b_save->bs_children = (struct buf **) (b_save + 1);
+	bp->b_saveaddr = b_save;
+	bp->b_bcount = 0;
+	bp->b_bufsize = 0;
+	bp->b_npages = 0;
+
+	if (tbp->b_flags & B_VMIO)
+		bp->b_flags |= B_VMIO;
+
+	bp->b_blkno = tbp->b_blkno;
+	bp->b_lblkno = tbp->b_lblkno;
+	bp->b_flags |= B_CALL | B_BUSY | B_CLUSTER;
 	bp->b_iodone = cluster_callback;
-	cp = (char *)bp->b_data + size;
-	for (++start_lbn, i = 0; i < len; ++i, ++start_lbn) {
-		/*
-		 * Block is not in core or the non-sequential block
-		 * ending our cluster was part of the cluster (in which
-		 * case we don't want to write it twice).
-		 */
-		if (!incore(vp, start_lbn) ||
-		    (last_bp == NULL && start_lbn == lbn))
-			break;
+	pbgetvp(vp, bp);
 
-		/*
-		 * Get the desired block buffer (unless it is the final
-		 * sequential block whose buffer was passed in explictly
-		 * as last_bp).
-		 */
-		if (last_bp == NULL || start_lbn != lbn) {
-			tbp = getblk(vp, start_lbn, size, 0, 0);
-			if (!(tbp->b_flags & B_DELWRI)) {
-				brelse(tbp);
+	for (i = 0; i < len; ++i, ++start_lbn) {
+		if (i != 0) {
+			/*
+			 * Block is not in core or the non-sequential block
+			 * ending our cluster was part of the cluster (in
+			 * which case we don't want to write it twice).
+			 */
+			if (!(tbp = incore(vp, start_lbn)) ||
+			    (last_bp == NULL && start_lbn == lbn))
 				break;
-			}
-		} else
-			tbp = last_bp;
 
-		++b_save->bs_nchildren;
+			if ((tbp->b_flags & (B_INVAL | B_BUSY | B_CLUSTEROK)) != B_CLUSTEROK)
+				break;
 
-		/* Move memory from children to parent */
-		if (tbp->b_blkno != (bp->b_blkno + btodb(bp->b_bufsize))) {
-			printf("Clustered Block: %lu addr %lx bufsize: %ld\n",
-			    (u_long)bp->b_lblkno, bp->b_blkno, bp->b_bufsize);
-			printf("Child Block: %lu addr: %lx\n", 
-			    (u_long)tbp->b_lblkno, tbp->b_blkno);
-			panic("Clustered write to wrong blocks");
+			/*
+			 * Get the desired block buffer (unless it is the
+			 * final sequential block whose buffer was passed in
+			 * explictly as last_bp).
+			 */
+			if (last_bp == NULL || start_lbn != lbn) {
+				tbp = getblk(vp, start_lbn, size, 0, 0);
+				if (!(tbp->b_flags & B_DELWRI) ||
+				    ((tbp->b_flags & B_VMIO) != (bp->b_flags & B_VMIO))) {
+					brelse(tbp);
+					break;
+				}
+			} else
+				tbp = last_bp;
 		}
-
-		pagemove(tbp->b_data, cp, size);
+		for (j = 0; j < tbp->b_npages; j += 1) {
+			bp->b_pages[j + bp->b_npages] = tbp->b_pages[j];
+		}
+		bp->b_npages += tbp->b_npages;
 		bp->b_bcount += size;
 		bp->b_bufsize += size;
 
-		tbp->b_bufsize -= size;
 		tbp->b_flags &= ~(B_READ | B_DONE | B_ERROR | B_DELWRI);
 		tbp->b_flags |= B_ASYNC;
 		s = splbio();
-		reassignbuf(tbp, tbp->b_vp);		/* put on clean list */
+		reassignbuf(tbp, tbp->b_vp);	/* put on clean list */
 		++tbp->b_vp->v_numoutput;
 		splx(s);
 		b_save->bs_children[i] = tbp;
-
-		cp += size;
-	}
-
-	if (i == 0) {
-		/* None to cluster */
-		bp->b_saveaddr = b_save->bs_saveaddr;
-		bp->b_flags &= ~B_CALL;
-		bp->b_iodone = NULL;
-		free(b_save, M_SEGMENT);
 	}
+	b_save->bs_nchildren = i;
+	pmap_qenter(bp->b_data, bp->b_pages, bp->b_npages);
 	bawrite(bp);
+
 	if (i < len) {
-		len -= i + 1;
-		start_lbn += 1;
+		len -= i;
 		goto redo;
 	}
 }
@@ -731,17 +608,17 @@ cluster_collectbufs(vp, last_bp)
 	struct buf *last_bp;
 {
 	struct cluster_save *buflist;
-	daddr_t	lbn;
+	daddr_t lbn;
 	int i, len;
 
 	len = vp->v_lastw - vp->v_cstart + 1;
 	buflist = malloc(sizeof(struct buf *) * (len + 1) + sizeof(*buflist),
 	    M_SEGMENT, M_WAITOK);
 	buflist->bs_nchildren = 0;
-	buflist->bs_children = (struct buf **)(buflist + 1);
+	buflist->bs_children = (struct buf **) (buflist + 1);
 	for (lbn = vp->v_cstart, i = 0; i < len; lbn++, i++)
-		    (void)bread(vp, lbn, last_bp->b_bcount, NOCRED,
-			&buflist->bs_children[i]);
+		(void) bread(vp, lbn, last_bp->b_bcount, NOCRED,
+		    &buflist->bs_children[i]);
 	buflist->bs_children[i] = last_bp;
 	buflist->bs_nchildren = i + 1;
 	return (buflist);