From 99c9264eec8fe529aa3074c739ecc4f9a2212714 Mon Sep 17 00:00:00 2001
From: tholo <tholo@openbsd.org>
Date: Mon, 14 Apr 1997 04:23:21 +0000
Subject: [PATCH] Minor performance enhancements from NetBSD

---
 sys/kern/vfs_bio.c  | 36 ++++++++++++++++++++++++++++++++++--
 sys/kern/vfs_subr.c |  8 +++-----
 sys/sys/buf.h       |  5 +++--
 3 files changed, 40 insertions(+), 9 deletions(-)

diff --git a/sys/kern/vfs_bio.c b/sys/kern/vfs_bio.c
index 33ad1cad470..ffa423f0c88 100644
--- a/sys/kern/vfs_bio.c
+++ b/sys/kern/vfs_bio.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_bio.c,v 1.13 1997/01/05 11:09:01 niklas Exp $	*/
+/*	$OpenBSD: vfs_bio.c,v 1.14 1997/04/14 04:23:23 tholo Exp $	*/
 /*	$NetBSD: vfs_bio.c,v 1.44 1996/06/11 11:15:36 pk Exp $	*/
 
 /*-
@@ -602,6 +602,20 @@ brelse(bp)
 	if (ISSET(bp->b_flags, (B_NOCACHE|B_ERROR)))
 		SET(bp->b_flags, B_INVAL);
 
+	if (ISSET(bp->b_flags, B_VFLUSH)) {
+		/*
+		 * This is a delayed write buffer that was just flushed to
+		 * disk.  It is still on the LRU queue.  If it's become
+		 * invalid, then we need to move it to a different queue;
+		 * otherwise leave it in its current position.
+		 */
+		CLR(bp->b_flags, B_VFLUSH);
+		if (!ISSET(bp->b_flags, B_ERROR|B_INVAL|B_LOCKED|B_AGE))
+			goto already_queued;
+		else
+			bremfree(bp);
+	}
+
 	if ((bp->b_bufsize <= 0) || ISSET(bp->b_flags, B_INVAL)) {
 		/*
 		 * If it's invalid or empty, dissociate it from its vnode
@@ -636,6 +650,7 @@ brelse(bp)
 		binstailfree(bp, bufq);
 	}
 
+already_queued:
 	/* Unlock the buffer. */
 	CLR(bp->b_flags, (B_AGE | B_ASYNC | B_BUSY | B_NOCACHE));
 
@@ -870,13 +885,30 @@ start:
 		return (0);
 	}
 
+	if (ISSET(bp->b_flags, B_VFLUSH)) {
+		/*
+		 * This is a delayed write buffer being flushed to disk.  Make
+		 * sure it gets aged out of the queue when it's finished, and
+		 * leave it off the LRU queue.
+		 */
+		CLR(bp->b_flags, B_VFLUSH);
+		SET(bp->b_flags, B_AGE);
+		splx(s);
+		goto start;
+	}
+
 	/* Buffer is no longer on free lists. */
 	SET(bp->b_flags, B_BUSY);
 
 	/* If buffer was a delayed write, start it, and go back to the top. */
 	if (ISSET(bp->b_flags, B_DELWRI)) {
 		splx(s);
-		bawrite (bp);
+		/*
+		 * This buffer has gone through the LRU, so make sure it gets
+		 * reused ASAP.
+		 */
+		SET(bp->b_flags, B_AGE);
+		bawrite(bp);
 		goto start;
 	}
 
diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 2c05c9f01f8..0d2ac94fbc1 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.8 1997/02/24 14:20:02 niklas Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.9 1997/04/14 04:23:26 tholo Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -467,8 +467,7 @@ vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
 					return (error);
 				break;
 			}
-			bremfree(bp);
-			bp->b_flags |= B_BUSY;
+			bp->b_flags |= B_BUSY | B_VFLUSH;
 			splx(s);
 			/*
 			 * XXX Since there are no node locks for NFS, I believe
@@ -505,8 +504,7 @@ loop:
 			continue;
 		if ((bp->b_flags & B_DELWRI) == 0)
 			panic("vflushbuf: not dirty");
-		bremfree(bp);
-		bp->b_flags |= B_BUSY;
+		bp->b_flags |= B_BUSY | B_VFLUSH;
 		splx(s);
 		/*
 		 * Wait for I/O associated with indirect blocks to complete,
diff --git a/sys/sys/buf.h b/sys/sys/buf.h
index 888eca306c6..c96a71a1765 100644
--- a/sys/sys/buf.h
+++ b/sys/sys/buf.h
@@ -1,5 +1,5 @@
-/*	$OpenBSD: buf.h,v 1.5 1996/06/11 03:25:14 tholo Exp $	*/
-/*	$NetBSD: buf.h,v 1.24 1996/02/18 11:55:45 fvdl Exp $	*/
+/*	$OpenBSD: buf.h,v 1.6 1997/04/14 04:23:21 tholo Exp $	*/
+/*	$NetBSD: buf.h,v 1.25 1997/04/09 21:12:17 mycroft Exp $	*/
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -124,6 +124,7 @@ struct buf {
 #define	B_WRITE		0x00000000	/* Write buffer (pseudo flag). */
 #define	B_WRITEINPROG	0x01000000	/* Write in progress. */
 #define	B_XXX		0x02000000	/* Debugging flag. */
+#define	B_VFLUSH	0x04000000	/* Buffer is being synced. */
 
 /*
  * This structure describes a clustered I/O.  It is stored in the b_saveaddr
-- 
2.20.1