Apply by doing:
cd /usr/src/sys
patch -p0 < bmap.patch
And then rebuild your kernel.
Index: ufs/ext2fs/ext2fs_bmap.c
===================================================================
RCS file: /cvs/src/sys/ufs/ext2fs/ext2fs_bmap.c,v
retrieving revision 1.3
retrieving revision 1.4
diff -u -r1.3 -r1.4
--- ufs/ext2fs/ext2fs_bmap.c 1997/06/12 21:09:31 1.3
+++ ufs/ext2fs/ext2fs_bmap.c 1999/04/25 00:36:46 1.4
@@ -120,7 +120,7 @@
struct ufsmount *ump;
struct mount *mp;
struct vnode *devvp;
- struct indir a[NIADDR], *xap;
+ struct indir a[NIADDR+1], *xap;
daddr_t daddr;
long metalbn;
int error, maxrun = 0, num;
Index: ufs/ufs/ufs_bmap.c
===================================================================
RCS file: /cvs/src/sys/ufs/ufs/ufs_bmap.c,v
retrieving revision 1.4
retrieving revision 1.5
diff -u -r1.4 -r1.5
--- ufs/ufs/ufs_bmap.c 1997/05/30 08:35:02 1.4
+++ ufs/ufs/ufs_bmap.c 1999/04/25 00:36:47 1.5
@@ -114,7 +114,7 @@
struct ufsmount *ump;
struct mount *mp;
struct vnode *devvp;
- struct indir a[NIADDR], *xap;
+ struct indir a[NIADDR+1], *xap;
daddr_t daddr;
long metalbn;
#ifdef TRACE