From 36046fc79fdc3cb6995cb236a86f994e022e6cf8 Mon Sep 17 00:00:00 2001
From: hannken <hannken@NetBSD.org>
Date: Sat, 23 Apr 2011 07:36:02 +0000
Subject: [PATCH] Try to keep snapshot indirect blocks contiguous.

This speeds up snapshot creation by a factor of ~3 and reduces
the file system suspension time by a factor of ~5.
---
 sys/ufs/ffs/ffs_balloc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/sys/ufs/ffs/ffs_balloc.c b/sys/ufs/ffs/ffs_balloc.c
index b97dc23e3a81..3683cbb19218 100644
--- a/sys/ufs/ffs/ffs_balloc.c
+++ b/sys/ufs/ffs/ffs_balloc.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: ffs_balloc.c,v 1.53 2011/03/06 17:08:38 bouyer Exp $	*/
+/*	$NetBSD: ffs_balloc.c,v 1.54 2011/04/23 07:36:02 hannken Exp $	*/
 
 /*
  * Copyright (c) 2002 Networks Associates Technology, Inc.
@@ -41,7 +41,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ffs_balloc.c,v 1.53 2011/03/06 17:08:38 bouyer Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ffs_balloc.c,v 1.54 2011/04/23 07:36:02 hannken Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_quota.h"
@@ -320,6 +320,10 @@ ffs_balloc_ufs1(struct vnode *vp, off_t off, int size, kauth_cred_t cred,
 			goto fail;
 		}
 		mutex_enter(&ump->um_lock);
+		/* Try to keep snapshot indirect blocks contiguous. */
+		if (i == num && (ip->i_flags & SF_SNAPSHOT) != 0)
+			pref = ffs_blkpref_ufs1(ip, lbn, indirs[i-1].in_off,
+			    flags | B_METAONLY, &bap[0]);
 		if (pref == 0)
 			pref = ffs_blkpref_ufs1(ip, lbn, 0, flags | B_METAONLY,
 			    NULL);
@@ -846,6 +850,10 @@ ffs_balloc_ufs2(struct vnode *vp, off_t off, int size, kauth_cred_t cred,
 			goto fail;
 		}
 		mutex_enter(&ump->um_lock);
+		/* Try to keep snapshot indirect blocks contiguous. */
+		if (i == num && (ip->i_flags & SF_SNAPSHOT) != 0)
+			pref = ffs_blkpref_ufs2(ip, lbn, indirs[i-1].in_off,
+			    flags | B_METAONLY, &bap[0]);
 		if (pref == 0)
 			pref = ffs_blkpref_ufs2(ip, lbn, 0, flags | B_METAONLY,
 			    NULL);