Buffer cache revamp

1) remove multiple size queues, introduced as a stopgap.
2) decouple pages containing data from their mappings
3) only keep buffers mapped when they actually have to be mapped
  (right now, this is when buffers are B_BUSY)
4) New functions to make a buffer busy, and release the busy flag
   (buf_acquire and buf_release)
5) Move high/low water marks and statistics counters into a structure
6) Add a sysctl to retrieve buffer cache statistics

Tested in several variants and beat upon by bob and art for a year. run
accidentally on henning's nfs server for a few months...

ok deraadt@, krw@, art@ - who promises to be around to deal with any fallout

1 files changed, 11 insertions, 6 deletions

diff --git a/sys/nfs/nfs_vnops.c b/sys/nfs/nfs_vnops.c
index be30de9f5f4..d26824f8b0e 100644
--- a/sys/nfs/nfs_vnops.c
+++ b/sys/nfs/nfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: nfs_vnops.c,v 1.84 2008/06/09 23:38:37 millert Exp $	*/
+/*	$OpenBSD: nfs_vnops.c,v 1.85 2008/06/10 20:14:37 beck Exp $	*/
 /*	$NetBSD: nfs_vnops.c,v 1.62.4.1 1996/07/08 20:26:52 jtc Exp $	*/
 
 /*
@@ -2675,7 +2675,8 @@ again:
 				!= (B_DELWRI | B_NEEDCOMMIT))
 				continue;
 			bremfree(bp);
-			bp->b_flags |= (B_BUSY | B_WRITEINPROG);
+			bp->b_flags |= B_WRITEINPROG;
+			buf_acquire(bp);
 			/*
 			 * A list of these buffers is kept so that the
 			 * second loop knows which buffers have actually
@@ -2753,10 +2754,12 @@ loop:
 		if ((passone || !commit) && (bp->b_flags & B_NEEDCOMMIT))
 			continue;
 		bremfree(bp);
-		if (passone || !commit)
-		    bp->b_flags |= (B_BUSY|B_ASYNC);
-		else
-		    bp->b_flags |= (B_BUSY|B_ASYNC|B_WRITEINPROG|B_NEEDCOMMIT);
+		if (passone || !commit) {
+			bp->b_flags |= B_ASYNC;
+		} else {
+			bp->b_flags |= (B_ASYNC|B_WRITEINPROG|B_NEEDCOMMIT);
+		}
+		buf_acquire(bp);
 		splx(s);
 		VOP_BWRITE(bp);
 		goto loop;
@@ -2952,6 +2955,8 @@ nfs_writebp(bp, force)
 	if (retv) {
 		if (force)
 			bp->b_flags |= B_WRITEINPROG;
+		bcstats.pendingwrites++;
+		bcstats.numwrites++;
 		VOP_STRATEGY(bp);
 	}