[src/trunk]: src/sbin/fsck_ffs add comments to make it clearer what cmpsblks(...

[lukem <lukem%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a23a9a53e8b9
branches:  trunk
changeset: 515171:a23a9a53e8b9
user:      lukem <lukem%NetBSD.org@localhost>
date:      Tue Sep 18 08:38:28 2001 +0000

description:
add comments to make it clearer what cmpsblks() is doing

diffstat:

 sbin/fsck_ffs/setup.c |  17 ++++++++++++++---
 1 files changed, 14 insertions(+), 3 deletions(-)

diffs (52 lines):

diff -r d00e92f4bd67 -r a23a9a53e8b9 sbin/fsck_ffs/setup.c
--- a/sbin/fsck_ffs/setup.c     Tue Sep 18 06:29:08 2001 +0000
+++ b/sbin/fsck_ffs/setup.c     Tue Sep 18 08:38:28 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: setup.c,v 1.49 2001/09/06 02:16:00 lukem Exp $ */
+/*     $NetBSD: setup.c,v 1.50 2001/09/18 08:38:28 lukem Exp $ */
 
 /*
  * Copyright (c) 1980, 1986, 1993
@@ -38,7 +38,7 @@
 #if 0
 static char sccsid[] = "@(#)setup.c    8.10 (Berkeley) 5/9/95";
 #else
-__RCSID("$NetBSD: setup.c,v 1.49 2001/09/06 02:16:00 lukem Exp $");
+__RCSID("$NetBSD: setup.c,v 1.50 2001/09/18 08:38:28 lukem Exp $");
 #endif
 #endif /* not lint */
 
@@ -577,6 +577,13 @@
 cmpsblks(const struct fs *sb, struct fs *asb)
 {
 
+       /*
+        * Copy fields which we don't care if they're different in the
+        * alternate superblocks, as they're either likely to be
+        * different because they're per-cylinder-group specific, or
+        * because they're transient details which are only maintained
+        * in the primary superblock.
+        */
        asb->fs_firstfield = sb->fs_firstfield;
        asb->fs_unused_1 = sb->fs_unused_1;
        asb->fs_time = sb->fs_time;
@@ -603,7 +610,7 @@
        memmove(asb->fs_sparecon,
                sb->fs_sparecon, sizeof sb->fs_sparecon);
        /*
-        * The following should not have to be copied.
+        * The following should not have to be copied, but need to be.
         */
        asb->fs_fsbtodb = sb->fs_fsbtodb;
        asb->fs_interleave = sb->fs_interleave;
@@ -614,6 +621,10 @@
        asb->fs_state = sb->fs_state;
        asb->fs_maxfilesize = sb->fs_maxfilesize;
 
+       /*
+        * Compare the superblocks, effectively checking every other
+        * field to see if they differ.
+        */
        return (memcmp(sb, asb, (int)sb->fs_sbsize));
 }