In kern_physio.c fix tsleep priority messup.

In vfs_bio.c, remove b_generation count usage, remove redundant reassignbuf, remove redundant spl(s), manage page PG_ZERO flags more correctly, utilize in invalid value for b_offset until it is properly initialized. Add asserts for #ifdef DIAGNOSTIC, when b_offset is improperly used. when a process is not performing I/O, and just waiting on a buffer generally, make the sleep priority low. only check page validity in getblk for B_VMIO buffers. In vfs_cluster, add b_offset asserts, correct pointer calculation for clustered reads. Improve readability of certain parts of the code. Remove redundant spl(s). In vfs_subr, correct usage of vfs_bio_awrite (From Andrew Gallatin <gallatin@cs.duke.edu>). More vtruncbuf problems fixed.
1998-03-19 22:48:16 +00:00 · 1998-03-19 22:48:16 +00:00 · 85baaa0265
commit 85baaa0265
parent eb6e0e64d3
5 changed files with 166 additions and 113 deletions
--- a/sys/kern/kern_physio.c
+++ b/sys/kern/kern_physio.c
@ -16,7 +16,7 @@
 * 4. Modifications may be freely made to this file if the above conditions
 *    are met.
 *
- * $Id: kern_physio.c,v 1.22 1997/09/02 20:05:40 bde Exp $
+ * $Id: kern_physio.c,v 1.23 1998/01/24 02:01:18 dyson Exp $
 */

 #include <sys/param.h>
@ -112,11 +112,7 @@ physio(strategy, bp, dev, rw, minp, uio)

 			spl = splbio();
 			while ((bp->b_flags & B_DONE) == 0)
-#if defined(NO_SCHEDULE_MODS)
 				tsleep((caddr_t)bp, PRIBIO, "physstr", 0);
-#else
-				tsleep((caddr_t)bp, curproc->p_usrpri, "physstr", 0);
-#endif
 			splx(spl);

 			/* release mapping into kernel space */
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@ -11,7 +11,7 @@
 * 2. Absolutely no warranty of function or purpose is made by the author
 *		John S. Dyson.
 *
- * $Id: vfs_bio.c,v 1.157 1998/03/17 08:41:28 kato Exp $
+ * $Id: vfs_bio.c,v 1.158 1998/03/17 17:36:05 dyson Exp $
 */

 /*
@ -183,7 +183,6 @@ bufinit()
 		bp->b_wcred = NOCRED;
 		bp->b_qindex = QUEUE_EMPTY;
 		bp->b_vnbufs.le_next = NOLIST;
-		bp->b_generation = 0;
 		LIST_INIT(&bp->b_dep);
 		TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist);
 		LIST_INSERT_HEAD(&invalhash, bp, b_hash);
@ -367,7 +366,7 @@ breadn(struct vnode * vp, daddr_t blkno, int size,
 int
 bwrite(struct buf * bp)
 {
-	int oldflags = bp->b_flags;
+	int oldflags;
 	struct vnode *vp;
 	struct mount *mp;

@ -376,8 +375,11 @@ bwrite(struct buf * bp)
 		brelse(bp);
 		return (0);
 	}
+
+	oldflags = bp->b_flags;
+
 #if !defined(MAX_PERF)
-	if (!(bp->b_flags & B_BUSY))
+	if ((bp->b_flags & B_BUSY) == 0)
 		panic("bwrite: buffer is not busy???");
 #endif

@ -414,10 +416,6 @@ bwrite(struct buf * bp)

 	if ((oldflags & B_ASYNC) == 0) {
 		int rtval = biowait(bp);
-
-		if (oldflags & B_DELWRI) {
-			reassignbuf(bp, bp->b_vp);
-		}
 		brelse(bp);
 		return (rtval);
 	}
@ -466,9 +464,7 @@ bdwrite(struct buf * bp)
 	bp->b_flags &= ~(B_READ|B_RELBUF);
 	if ((bp->b_flags & B_DELWRI) == 0) {
 		bp->b_flags |= B_DONE | B_DELWRI;
-		s = splbio();
 		reassignbuf(bp, bp->b_vp);
-		splx(s);
 		++numdirtybuffers;
 	}

@ -532,9 +528,7 @@ bdirty(bp)
 	bp->b_flags &= ~(B_READ|B_RELBUF); /* XXX ??? check this */
 	if ((bp->b_flags & B_DELWRI) == 0) {
 		bp->b_flags |= B_DONE | B_DELWRI; /* why done? XXX JRE */
-		s = splbio();
 		reassignbuf(bp, bp->b_vp);
-		splx(s);
 		++numdirtybuffers;
 	}
 }
@ -652,6 +646,7 @@ brelse(struct buf * bp)

 		for (i = 0; i < bp->b_npages; i++) {
 			m = bp->b_pages[i];
+			m->flags &= ~PG_ZERO;
 			if (m == bogus_page) {

 				obj = (vm_object_t) vp->v_object;
@ -673,7 +668,6 @@ brelse(struct buf * bp)
 				if ((bp->b_flags & B_INVAL) == 0) {
 					pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
 				}
-				break;
 			}
 			if (bp->b_flags & (B_NOCACHE|B_ERROR)) {
 				int poffset = foff & PAGE_MASK;
@ -709,7 +703,6 @@ brelse(struct buf * bp)
 		LIST_INSERT_HEAD(&invalhash, bp, b_hash);
 		bp->b_dev = NODEV;
 		kvafreespace += bp->b_kvasize;
-		bp->b_generation++;

 	/* buffers with junk contents */
 	} else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) {
@ -719,7 +712,6 @@ brelse(struct buf * bp)
 		LIST_REMOVE(bp, b_hash);
 		LIST_INSERT_HEAD(&invalhash, bp, b_hash);
 		bp->b_dev = NODEV;
-		bp->b_generation++;

 	/* buffers that are locked */
 	} else if (bp->b_flags & B_LOCKED) {
@ -748,7 +740,7 @@ brelse(struct buf * bp)

 	/* unlock */
 	bp->b_flags &= ~(B_ORDERED | B_WANTED | B_BUSY |
-				B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
+		B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF);
 	splx(s);
 }

@ -841,6 +833,7 @@ vfs_vmio_release(bp)
 						vm_page_cache(m);
 					else
 						vm_page_deactivate(m);
+					m->flags &= ~PG_ZERO;
 				} else if (m->hold_count == 0) {
 					m->flags |= PG_BUSY;
 					vm_page_protect(m, VM_PROT_NONE);
@ -852,6 +845,7 @@ vfs_vmio_release(bp)
 				 * act_count.
 				 */
 				m->act_count = 0;
+				m->flags &= ~PG_ZERO;
 			}
 		}
 	}
@ -942,11 +936,12 @@ vfs_bio_awrite(struct buf * bp)
 	}

 	bremfree(bp);
+	bp->b_flags |= B_BUSY | B_ASYNC;
+
 	splx(s);
 	/*
 	 * default (old) behavior, writing out only one block
 	 */
-	bp->b_flags |= B_BUSY | B_ASYNC;
 	nwritten = bp->b_bufsize;
 	(void) VOP_BWRITE(bp);
 	return nwritten;
@ -1121,7 +1116,6 @@ getnewbuf(struct vnode *vp, daddr_t blkno,
 		brelvp(bp);

 fillbuf:
-	bp->b_generation++;

 	/* we are not free, nor do we contain interesting data */
 	if (bp->b_rcred != NOCRED) {
@ -1145,7 +1139,7 @@ getnewbuf(struct vnode *vp, daddr_t blkno,
 	bp->b_dev = NODEV;
 	bp->b_vp = NULL;
 	bp->b_blkno = bp->b_lblkno = 0;
-	bp->b_offset = 0;
+	bp->b_offset = NOOFFSET;
 	bp->b_iodone = 0;
 	bp->b_error = 0;
 	bp->b_resid = 0;
@ -1359,8 +1353,10 @@ vfs_setdirty(struct buf *bp) {
 		 * test the pages to see if they have been modified directly
 		 * by users through the VM system.
 		 */
-		for (i = 0; i < bp->b_npages; i++)
+		for (i = 0; i < bp->b_npages; i++) {
+			bp->b_pages[i]->flags &= ~PG_ZERO;
 			vm_page_test_dirty(bp->b_pages[i]);
+		}

 		/*
 		 * scan forwards for the first page modified
@ -1428,7 +1424,6 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
 	}

 	if ((bp = gbincore(vp, blkno))) {
-		generation = bp->b_generation;
 loop1:
 		if (bp->b_flags & B_BUSY) {

@ -1438,9 +1433,7 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)

 			if (!tsleep(bp,
 				(PRIBIO + 4) | slpflag, "getblk", slptimeo)) {
-				if (bp->b_generation != generation)
-					goto loop;
-				goto loop1;
+				goto loop;
 			}

 			splx(s);
@ -1457,7 +1450,6 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
 		 */

 		if (bp->b_bcount != size) {
-			bp->b_generation++;
 			if ((bp->b_flags & B_VMIO) && (size <= bp->b_kvasize)) {
 				allocbuf(bp, size);
 			} else {
@ -1477,22 +1469,31 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
 			}
 		}

+#ifdef DIAGNOSTIC
+		if (bp->b_offset == NOOFFSET)
+			panic("getblk: no buffer offset");
+#endif
+
 		/*
 		 * Check that the constituted buffer really deserves for the
-		 * B_CACHE bit to be set.
+		 * B_CACHE bit to be set.  B_VMIO type buffers might not
+		 * contain fully valid pages.  Normal (old-style) buffers
+		 * should be fully valid.
 		 */
-		checksize = bp->b_bufsize;
-		for (i = 0; i < bp->b_npages; i++) {
-			int resid;
-			int poffset;
-			poffset = bp->b_offset & PAGE_MASK;
-			resid = (checksize > (PAGE_SIZE - poffset)) ?
-				(PAGE_SIZE - poffset) : checksize;
-			if (!vm_page_is_valid(bp->b_pages[i], poffset, resid)) {
-				bp->b_flags &= ~(B_CACHE | B_DONE);
-				break;
+		if (bp->b_flags & B_VMIO) {
+			checksize = bp->b_bufsize;
+			for (i = 0; i < bp->b_npages; i++) {
+				int resid;
+				int poffset;
+				poffset = bp->b_offset & PAGE_MASK;
+				resid = (checksize > (PAGE_SIZE - poffset)) ?
+					(PAGE_SIZE - poffset) : checksize;
+				if (!vm_page_is_valid(bp->b_pages[i], poffset, resid)) {
+					bp->b_flags &= ~(B_CACHE | B_DONE);
+					break;
+				}
+				checksize -= resid;
 			}
-			checksize -= resid;
 		}

 		if (bp->b_usecount < BUF_MAXUSE)
@ -1528,6 +1529,7 @@ getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo)
 		 * be found by incore.
 		 */
 		bp->b_blkno = bp->b_lblkno = blkno;
+
 		if (vp->v_type != VBLK)
 			bp->b_offset = (off_t) blkno * maxsize;
 		else
@ -1744,6 +1746,11 @@ allocbuf(struct buf * bp, int size)
 					tinc = bsize;

 				off = bp->b_offset;
+#ifdef DIAGNOSTIC
+				if (bp->b_offset == NOOFFSET)
+					panic("allocbuf: no buffer offset");
+#endif
+
 				curbpnpages = bp->b_npages;
 		doretry:
 				bp->b_validoff = orig_validoff;
@ -1801,6 +1808,7 @@ allocbuf(struct buf * bp, int size)
 							bytesinpage = newbsize - toff;
 						if (bp->b_flags & B_CACHE)
 							vfs_buf_set_valid(bp, off, toff, bytesinpage, m);
+						m->flags &= ~PG_ZERO;
 						vm_page_wire(m);
 					}
 					bp->b_pages[pageindex] = m;
@ -1890,9 +1898,11 @@ biodone(register struct buf * bp)
 	if ((bp->b_flags & B_READ) == 0) {
 		vwakeup(bp);
 	}
+
 #ifdef BOUNCE_BUFFERS
-	if (bp->b_flags & B_BOUNCE)
+	if (bp->b_flags & B_BOUNCE) {
 		vm_bounce_free(bp);
+	}
 #endif

 	/* call optional completion function if requested */
@ -1930,6 +1940,10 @@ biodone(register struct buf * bp)
 #endif

 		foff = bp->b_offset;
+#ifdef DIAGNOSTIC
+		if (bp->b_offset == NOOFFSET)
+			panic("biodone: no buffer offset");
+#endif

 #if !defined(MAX_PERF)
 		if (!obj) {
@ -1976,6 +1990,7 @@ biodone(register struct buf * bp)
 			if ((bp->b_flags & B_READ) && !bogusflag && resid > 0) {
 				vfs_page_set_valid(bp, foff, i, m);
 			}
+			m->flags &= ~PG_ZERO;

 			/*
 			 * when debugging new filesystems or buffer I/O methods, this
@ -2107,6 +2122,7 @@ vfs_unbusy_pages(struct buf * bp)
 				pmap_qenter(trunc_page(bp->b_data), bp->b_pages, bp->b_npages);
 			}
 			--obj->paging_in_progress;
+			m->flags &= ~PG_ZERO;
 			PAGE_BWAKEUP(m);
 		}
 		if (obj->paging_in_progress == 0 &&
@ -2211,6 +2227,10 @@ vfs_busy_pages(struct buf * bp, int clear_modify)
 		vm_ooffset_t foff;

 		foff = bp->b_offset;
+#ifdef DIAGNOSTIC
+		if (bp->b_offset == NOOFFSET)
+			panic("vfs_busy_pages: no buffer offset");
+#endif

 		vfs_setdirty(bp);

@ -2224,6 +2244,7 @@ vfs_busy_pages(struct buf * bp, int clear_modify)
 		for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) {
 			vm_page_t m = bp->b_pages[i];

+			m->flags &= ~PG_ZERO;
 			if ((bp->b_flags & B_CLUSTER) == 0) {
 				obj->paging_in_progress++;
 				m->busy++;
@ -2257,6 +2278,11 @@ vfs_clean_pages(struct buf * bp)
 		vm_ooffset_t foff;
 		foff = bp->b_offset;

+#ifdef DIAGNOSTIC
+		if (bp->b_offset == NOOFFSET)
+			panic("vfs_clean_pages: no buffer offset");
+#endif
+
 		for (i = 0; i < bp->b_npages; i++, foff += PAGE_SIZE) {
 			vm_page_t m = bp->b_pages[i];
 			vfs_page_set_valid(bp, foff, i, m);
@ -2267,13 +2293,15 @@ vfs_clean_pages(struct buf * bp)
 void
 vfs_bio_clrbuf(struct buf *bp) {
 	int i;
-	if( bp->b_flags & B_VMIO) {
+	if (((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) ||
+		((bp->b_flags & (B_VMIO | B_MALLOC)) == 0) && (bp->b_npages > 0) ) {
 		if( (bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE)) {
 			int mask;
 			mask = 0;
 			for(i=0;i<bp->b_bufsize;i+=DEV_BSIZE)
 				mask |= (1 << (i/DEV_BSIZE));
-			if( bp->b_pages[0]->valid != mask) {
+			if(((bp->b_pages[0]->flags & PG_ZERO) == 0) &&
+				(bp->b_pages[0]->valid != mask)) {
 				bzero(bp->b_data, bp->b_bufsize);
 			}
 			bp->b_pages[0]->valid = mask;
@ -2290,11 +2318,13 @@ vfs_bio_clrbuf(struct buf *bp) {
 			} else {
 				int j;
 				for(j=0;j<PAGE_SIZE/DEV_BSIZE;j++) {
-					if( (bp->b_pages[i]->valid & (1<<j)) == 0)
+					if (((bp->b_pages[i]->flags & PG_ZERO) == 0) &&
+						(bp->b_pages[i]->valid & (1<<j)) == 0)
 						bzero(bp->b_data + (i << PAGE_SHIFT) + j * DEV_BSIZE, DEV_BSIZE);
 				}
 			}
 			bp->b_pages[i]->valid = VM_PAGE_BITS_ALL;
+			bp->b_pages[i]->flags &= ~PG_ZERO;
 		}
 		bp->b_resid = 0;
 	} else {
--- a/sys/kern/vfs_cluster.c
+++ b/sys/kern/vfs_cluster.c
@ -33,7 +33,7 @@
 * SUCH DAMAGE.
 *
 *	@(#)vfs_cluster.c	8.7 (Berkeley) 2/13/94
- * $Id: vfs_cluster.c,v 1.58 1998/03/16 01:55:24 dyson Exp $
+ * $Id: vfs_cluster.c,v 1.59 1998/03/16 18:39:41 julian Exp $
 */

 #include "opt_debug_cluster.h"
@ -150,7 +150,7 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 					(i == (maxra - 1)))
 					tbp->b_flags |= B_RAM;

-				if ((tbp->b_usecount < 5) &&
+				if ((tbp->b_usecount < 1) &&
 					((tbp->b_flags & B_BUSY) == 0) &&
 					(tbp->b_qindex == QUEUE_LRU)) {
 					TAILQ_REMOVE(&bufqueues[QUEUE_LRU], tbp, b_freelist);
@ -167,6 +167,10 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)
 	} else {
 		off_t firstread;
 		firstread = bp->b_offset;
+#ifdef DIAGNOSTIC
+		if (bp->b_offset == NOOFFSET)
+			panic("cluster_read: no buffer offset");
+#endif
 		if (firstread + totread > filesize)
 			totread = filesize - firstread;
 		if (totread > size) {
@ -194,7 +198,7 @@ cluster_read(vp, filesize, lblkno, size, cred, totread, seqcount, bpp)

 			bp = cluster_rbuild(vp, filesize, lblkno,
 				blkno, size, nblks, bp);
-			lblkno += nblks;
+			lblkno += (bp->b_bufsize / size);
 		} else {
 single_block_read:
 			/*
@ -348,6 +352,10 @@ cluster_rbuild(vp, filesize, lbn, blkno, size, run, fbp)
 	bp->b_blkno = blkno;
 	bp->b_lblkno = lbn;
 	bp->b_offset = tbp->b_offset;
+#ifdef DIAGNOSTIC
+	if (bp->b_offset == NOOFFSET)
+		panic("cluster_rbuild: no buffer offset");
+#endif
 	pbgetvp(vp, bp);

 	TAILQ_INIT(&bp->b_cluster.cluster_head);
@ -511,6 +519,11 @@ cluster_write(bp, filesize)
 	}
 	lbn = bp->b_lblkno;

+#ifdef DIAGNOSTIC
+	if (bp->b_offset == NOOFFSET)
+		panic("cluster_write: no buffer offset");
+#endif
+
 	/* Initialize vnode to beginning of file. */
 	if (lbn == 0)
 		vp->v_lasta = vp->v_clen = vp->v_cstart = vp->v_lastw = 0;
@ -687,7 +700,7 @@ cluster_wbuild(vp, size, start_lbn, len)
 		(vm_offset_t) bp->b_data |=
 			((vm_offset_t) tbp->b_data) & PAGE_MASK;
 		bp->b_flags |= B_CALL | B_BUSY | B_CLUSTER |
-				(tbp->b_flags & (B_VMIO|B_NEEDCOMMIT));
+				(tbp->b_flags & (B_VMIO | B_NEEDCOMMIT));
 		bp->b_iodone = cluster_callback;
 		pbgetvp(vp, bp);
 		/*
@ -712,10 +725,10 @@ cluster_wbuild(vp, size, start_lbn, len)
 				 * characteristics, don't cluster with it.
 				 */
 				if ((tbp->b_flags &
-				  (B_VMIO|B_CLUSTEROK|B_INVAL|B_BUSY|
-				    B_DELWRI|B_NEEDCOMMIT))
-				  != (B_DELWRI|B_CLUSTEROK|
-				    (bp->b_flags & (B_VMIO|B_NEEDCOMMIT)))) {
+				  (B_VMIO | B_CLUSTEROK | B_INVAL | B_BUSY |
+				    B_DELWRI | B_NEEDCOMMIT))
+				  != (B_DELWRI | B_CLUSTEROK |
+				    (bp->b_flags & (B_VMIO | B_NEEDCOMMIT)))) {
 					splx(s);
 					break;
 				}
@ -732,7 +745,7 @@ cluster_wbuild(vp, size, start_lbn, len)
 				 */
 				if ((tbp->b_bcount != size) ||
 				  ((bp->b_blkno + (dbsize * i)) !=
-				    (tbp->b_blkno)) ||
+				    tbp->b_blkno) ||
 				  ((tbp->b_npages + bp->b_npages) >
 				    (vp->v_maxio / PAGE_SIZE))) {
 					splx(s);
@ -784,10 +797,8 @@ cluster_wbuild(vp, size, start_lbn, len)
 			--numdirtybuffers;
 			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 */
 			++tbp->b_vp->v_numoutput;
-			splx(s);
 			TAILQ_INSERT_TAIL(&bp->b_cluster.cluster_head,
 				tbp, b_cluster.cluster_entry);
 		}
--- a/sys/kern/vfs_export.c
+++ b/sys/kern/vfs_export.c
@ -36,7 +36,7 @@
 * SUCH DAMAGE.
 *
 *	@(#)vfs_subr.c	8.31 (Berkeley) 5/26/95
- * $Id: vfs_subr.c,v 1.143 1998/03/17 06:30:52 dyson Exp $
+ * $Id: vfs_subr.c,v 1.144 1998/03/19 18:46:58 dyson Exp $
 */

 /*
@ -601,7 +601,7 @@ vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
 			if (bp->b_flags & B_BUSY) {
 				bp->b_flags |= B_WANTED;
 				error = tsleep((caddr_t) bp,
-				    slpflag | (PRIBIO + 1), "vinvalbuf",
+				    slpflag | (PRIBIO + 4), "vinvalbuf",
 				    slptimeo);
 				if (error) {
 					splx(s);
@ -609,28 +609,34 @@ vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
 				}
 				break;
 			}
-			bremfree(bp);
-			bp->b_flags |= B_BUSY;
 			/*
 			 * XXX Since there are no node locks for NFS, I
 			 * believe there is a slight chance that a delayed
 			 * write will occur while sleeping just above, so
-			 * check for it.
+			 * check for it.  Note that vfs_bio_awrite expects
+			 * buffers to reside on a queue, while VOP_BWRITE and
+			 * brelse do not.
 			 */
-			if ((bp->b_flags & B_DELWRI) && (flags & V_SAVE)) {
+			if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
+				(flags & V_SAVE)) {
+
 				if (bp->b_vp == vp) {
 					if (bp->b_flags & B_CLUSTEROK) {
 						vfs_bio_awrite(bp);
 					} else {
-						bp->b_flags |= B_ASYNC;
+						bremfree(bp);
+						bp->b_flags |= (B_BUSY | B_ASYNC);
 						VOP_BWRITE(bp);
 					}
 				} else {
+					bremfree(bp);
+					bp->b_flags |= B_BUSY;
 					(void) VOP_BWRITE(bp);
 				}
 				break;
 			}
-			bp->b_flags |= (B_INVAL|B_NOCACHE|B_RELBUF);
+			bremfree(bp);
+			bp->b_flags |= (B_INVAL | B_NOCACHE | B_RELBUF | B_BUSY);
 			bp->b_flags &= ~B_ASYNC;
 			brelse(bp);
 		}
@ -679,7 +685,7 @@ vtruncbuf(vp, cred, p, length, blksize)
 {
 	register struct buf *bp;
 	struct buf *nbp, *blist;
-	int s, error, anyfreed, anymetadirty;
+	int s, error, anyfreed;
 	vm_object_t object;
 	int trunclbn;

@ -687,7 +693,6 @@ vtruncbuf(vp, cred, p, length, blksize)
 	 * Round up to the *next* lbn.
 	 */
 	trunclbn = (length + blksize - 1) / blksize;
-	anymetadirty = 0;

 	s = splbio();
 restart:
@ -701,17 +706,18 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if (bp->b_lblkno >= trunclbn) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb1", 0);
-					nbp = bp;
+					tsleep(bp, PRIBIO + 4, "vtrb1", 0);
+					goto restart;
 				} else {
 					bremfree(bp);
-					bp->b_flags |= (B_BUSY|B_INVAL|B_NOCACHE|B_RELBUF);
+					bp->b_flags |= (B_BUSY | B_INVAL | B_RELBUF);
 					bp->b_flags &= ~B_ASYNC;
 					brelse(bp);
 					anyfreed = 1;
 				}
 				if (nbp && 
-					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) || (nbp->b_vp != vp) ||
+					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) ||
+					 (nbp->b_vp != vp) ||
 					 (nbp->b_flags & B_DELWRI))) {
 					goto restart;
 				}
@ -725,28 +731,27 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if (bp->b_lblkno >= trunclbn) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb2", 0);
-					nbp = bp;
+					tsleep(bp, PRIBIO + 4, "vtrb2", 0);
+					goto restart;
 				} else {
 					bremfree(bp);
-					bp->b_flags |= (B_BUSY|B_INVAL|B_NOCACHE|B_RELBUF);
+					bp->b_flags |= (B_BUSY | B_INVAL | B_RELBUF);
 					bp->b_flags &= ~B_ASYNC;
 					brelse(bp);
 					anyfreed = 1;
 				}
 				if (nbp && 
-					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) || (nbp->b_vp != vp) ||
+					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) ||
+					 (nbp->b_vp != vp) ||
 					 (nbp->b_flags & B_DELWRI) == 0)) {
 					goto restart;
 				}
-			} else if (bp->b_lblkno < 0) {
-				anymetadirty++;
 			}
 		}
 	}

-rescan:
-	if ((length > 0) && anymetadirty) {
+	if (length > 0) {
+restartsync:
 		for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {

 			nbp = LIST_NEXT(bp, b_vnbufs);
@ -754,16 +759,20 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if ((bp->b_flags & B_DELWRI) && (bp->b_lblkno < 0)) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb3", 0);
-					nbp = bp;
-					continue;
+					tsleep(bp, PRIBIO, "vtrb3", 0);
 				} else {
 					bremfree(bp);
-					bp->b_flags |= B_ASYNC | B_BUSY;
+					bp->b_flags |= B_BUSY;
+					if (bp->b_vp == vp) {
+						bp->b_flags |= B_ASYNC;
+					} else {
+						bp->b_flags &= ~B_ASYNC;
+					}
 					VOP_BWRITE(bp);
-					goto rescan;
 				}
+				goto restartsync;
 			}
+
 		}
 	}

@ -772,7 +781,6 @@ vtruncbuf(vp, cred, p, length, blksize)
 		tsleep(&vp->v_numoutput, PVM, "vbtrunc", 0);
 	}

-
 	splx(s);

 	vnode_pager_setsize(vp, length);
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@ -36,7 +36,7 @@
 * SUCH DAMAGE.
 *
 *	@(#)vfs_subr.c	8.31 (Berkeley) 5/26/95
- * $Id: vfs_subr.c,v 1.143 1998/03/17 06:30:52 dyson Exp $
+ * $Id: vfs_subr.c,v 1.144 1998/03/19 18:46:58 dyson Exp $
 */

 /*
@ -601,7 +601,7 @@ vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
 			if (bp->b_flags & B_BUSY) {
 				bp->b_flags |= B_WANTED;
 				error = tsleep((caddr_t) bp,
-				    slpflag | (PRIBIO + 1), "vinvalbuf",
+				    slpflag | (PRIBIO + 4), "vinvalbuf",
 				    slptimeo);
 				if (error) {
 					splx(s);
@ -609,28 +609,34 @@ vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
 				}
 				break;
 			}
-			bremfree(bp);
-			bp->b_flags |= B_BUSY;
 			/*
 			 * XXX Since there are no node locks for NFS, I
 			 * believe there is a slight chance that a delayed
 			 * write will occur while sleeping just above, so
-			 * check for it.
+			 * check for it.  Note that vfs_bio_awrite expects
+			 * buffers to reside on a queue, while VOP_BWRITE and
+			 * brelse do not.
 			 */
-			if ((bp->b_flags & B_DELWRI) && (flags & V_SAVE)) {
+			if (((bp->b_flags & (B_DELWRI | B_INVAL)) == B_DELWRI) &&
+				(flags & V_SAVE)) {
+
 				if (bp->b_vp == vp) {
 					if (bp->b_flags & B_CLUSTEROK) {
 						vfs_bio_awrite(bp);
 					} else {
-						bp->b_flags |= B_ASYNC;
+						bremfree(bp);
+						bp->b_flags |= (B_BUSY | B_ASYNC);
 						VOP_BWRITE(bp);
 					}
 				} else {
+					bremfree(bp);
+					bp->b_flags |= B_BUSY;
 					(void) VOP_BWRITE(bp);
 				}
 				break;
 			}
-			bp->b_flags |= (B_INVAL|B_NOCACHE|B_RELBUF);
+			bremfree(bp);
+			bp->b_flags |= (B_INVAL | B_NOCACHE | B_RELBUF | B_BUSY);
 			bp->b_flags &= ~B_ASYNC;
 			brelse(bp);
 		}
@ -679,7 +685,7 @@ vtruncbuf(vp, cred, p, length, blksize)
 {
 	register struct buf *bp;
 	struct buf *nbp, *blist;
-	int s, error, anyfreed, anymetadirty;
+	int s, error, anyfreed;
 	vm_object_t object;
 	int trunclbn;

@ -687,7 +693,6 @@ vtruncbuf(vp, cred, p, length, blksize)
 	 * Round up to the *next* lbn.
 	 */
 	trunclbn = (length + blksize - 1) / blksize;
-	anymetadirty = 0;

 	s = splbio();
 restart:
@ -701,17 +706,18 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if (bp->b_lblkno >= trunclbn) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb1", 0);
-					nbp = bp;
+					tsleep(bp, PRIBIO + 4, "vtrb1", 0);
+					goto restart;
 				} else {
 					bremfree(bp);
-					bp->b_flags |= (B_BUSY|B_INVAL|B_NOCACHE|B_RELBUF);
+					bp->b_flags |= (B_BUSY | B_INVAL | B_RELBUF);
 					bp->b_flags &= ~B_ASYNC;
 					brelse(bp);
 					anyfreed = 1;
 				}
 				if (nbp && 
-					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) || (nbp->b_vp != vp) ||
+					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) ||
+					 (nbp->b_vp != vp) ||
 					 (nbp->b_flags & B_DELWRI))) {
 					goto restart;
 				}
@ -725,28 +731,27 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if (bp->b_lblkno >= trunclbn) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb2", 0);
-					nbp = bp;
+					tsleep(bp, PRIBIO + 4, "vtrb2", 0);
+					goto restart;
 				} else {
 					bremfree(bp);
-					bp->b_flags |= (B_BUSY|B_INVAL|B_NOCACHE|B_RELBUF);
+					bp->b_flags |= (B_BUSY | B_INVAL | B_RELBUF);
 					bp->b_flags &= ~B_ASYNC;
 					brelse(bp);
 					anyfreed = 1;
 				}
 				if (nbp && 
-					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) || (nbp->b_vp != vp) ||
+					((LIST_NEXT(nbp, b_vnbufs) == NOLIST) ||
+					 (nbp->b_vp != vp) ||
 					 (nbp->b_flags & B_DELWRI) == 0)) {
 					goto restart;
 				}
-			} else if (bp->b_lblkno < 0) {
-				anymetadirty++;
 			}
 		}
 	}

-rescan:
-	if ((length > 0) && anymetadirty) {
+	if (length > 0) {
+restartsync:
 		for (bp = LIST_FIRST(&vp->v_dirtyblkhd); bp; bp = nbp) {

 			nbp = LIST_NEXT(bp, b_vnbufs);
@ -754,16 +759,20 @@ vtruncbuf(vp, cred, p, length, blksize)
 			if ((bp->b_flags & B_DELWRI) && (bp->b_lblkno < 0)) {
 				if (bp->b_flags & B_BUSY) {
 					bp->b_flags |= B_WANTED;
-					tsleep((caddr_t) bp, PRIBIO, "vtrb3", 0);
-					nbp = bp;
-					continue;
+					tsleep(bp, PRIBIO, "vtrb3", 0);
 				} else {
 					bremfree(bp);
-					bp->b_flags |= B_ASYNC | B_BUSY;
+					bp->b_flags |= B_BUSY;
+					if (bp->b_vp == vp) {
+						bp->b_flags |= B_ASYNC;
+					} else {
+						bp->b_flags &= ~B_ASYNC;
+					}
 					VOP_BWRITE(bp);
-					goto rescan;
 				}
+				goto restartsync;
 			}
+
 		}
 	}

@ -772,7 +781,6 @@ vtruncbuf(vp, cred, p, length, blksize)
 		tsleep(&vp->v_numoutput, PVM, "vbtrunc", 0);
 	}

-
 	splx(s);

 	vnode_pager_setsize(vp, length);