When truncating directories by less than a block we shouldn't zero the

part of the block that we're deallocating.
From NetBSD.

1 files changed, 8 insertions, 5 deletions

diff --git a/sys/ufs/ffs/ffs_inode.c b/sys/ufs/ffs/ffs_inode.c
index 21978dbb82b..225ccc23acb 100644
--- a/sys/ufs/ffs/ffs_inode.c
+++ b/sys/ufs/ffs/ffs_inode.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: ffs_inode.c,v 1.14 1999/12/06 07:03:04 art Exp $	*/
+/*	$OpenBSD: ffs_inode.c,v 1.15 1999/12/06 07:23:21 art Exp $	*/
 /*	$NetBSD: ffs_inode.c,v 1.10 1996/05/11 18:27:19 mycroft Exp $	*/
 
 /*
@@ -275,10 +275,11 @@ ffs_truncate(v)
 
 	/*
 	 * Shorten the size of the file. If the file is not being
-	 * truncated to a block boundry, the contents of the
+	 * truncated to a block boundary, the contents of the
 	 * partial block following the end of the file must be
-	 * zero'ed in case it ever become accessable again because
-	 * of subsequent file growth.
+	 * zero'ed in case it ever become accessible again because
+	 * of subsequent file growth. Directories however are not
+	 * zero'ed as they should grow back initialized to empty.
 	 */
 	offset = blkoff(fs, length);
 	if (offset == 0) {
@@ -299,7 +300,9 @@ ffs_truncate(v)
 #else
 		(void) vnode_pager_uncache(ovp);
 #endif
-		bzero((char *)bp->b_data + offset, (u_int)(size - offset));
+		if (ovp->v_type != VDIR)
+			bzero((char *)bp->b_data + offset,
+			      (u_int)(size - offset));
 		allocbuf(bp, size);
 		if (aflags & B_SYNC)
 			bwrite(bp);