[src/trunk]: src/sys/ufs/ffs Change comments - one I wrote earlier wasn't right.

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

details:   https://anonhg.NetBSD.org/src/rev/45f3305886e6
branches:  trunk
changeset: 559581:45f3305886e6
user:      dsl <dsl%NetBSD.org@localhost>
date:      Sat Mar 20 17:26:16 2004 +0000

description:
Change comments - one I wrote earlier wasn't right.
Add a couple of notes about areas of the superblock being reassigned
when ffsv2 was imported.

diffstat:

 sys/ufs/ffs/fs.h |  11 ++++++++---
 1 files changed, 8 insertions(+), 3 deletions(-)

diffs (51 lines):

diff -r 957c84a15ed1 -r 45f3305886e6 sys/ufs/ffs/fs.h
--- a/sys/ufs/ffs/fs.h  Sat Mar 20 17:13:39 2004 +0000
+++ b/sys/ufs/ffs/fs.h  Sat Mar 20 17:26:16 2004 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: fs.h,v 1.41 2004/03/20 15:37:12 dsl Exp $      */
+/*     $NetBSD: fs.h,v 1.42 2004/03/20 17:26:16 dsl Exp $      */
 
 /*
  * Copyright (c) 1982, 1986, 1993
@@ -88,8 +88,9 @@
 #define SBLOCK_PIGGY  262144
 #define SBLOCKSIZE      8192
 /*
- * NB ensure you check fs->fs_sblockloc == SBLOCKSEARCH[i] before assuming
- * that the superblock is valid.
+ * NB: Do not, under any circumstances, look for an ffsv1 filesystem at
+ * SBLOCK_UFS2.  Doing so will find the wrong superblock for filesystems
+ * with a 64k block size.
  */
 #define SBLOCKSEARCH \
        { SBLOCK_UFS2, SBLOCK_UFS1, SBLOCK_FLOPPY, SBLOCK_PIGGY, -1 }
@@ -141,6 +142,7 @@
 /*
  * The volume name for this filesystem is maintained in fs_volname.
  * MAXVOLLEN defines the length of the buffer allocated.
+ * This space used to be part of of fs_fsmnt.
  */
 #define MAXVOLLEN      32
 
@@ -300,6 +302,7 @@
        int32_t *fs_maxcluster;         /* max cluster in each cyl group */
        u_int   *fs_active;             /* used by snapshots to track fs */
        int32_t  fs_old_cpc;            /* cyl per cycle in postbl */
+/* this area is otherwise allocated in filesystems created before ffsv2 */
        int32_t  fs_maxbsize;           /* maximum blocking factor permitted */
        int64_t  fs_sparecon64[17];     /* old rotation block list head */
        int64_t  fs_sblockloc;          /* byte offset of standard superblock */
@@ -311,11 +314,13 @@
        int64_t  fs_pendingblocks;      /* blocks in process of being freed */
        int32_t  fs_pendinginodes;      /* inodes in process of being freed */
        int32_t  fs_snapinum[FSMAXSNAP];/* list of snapshot inode numbers */
+/* back to stuff that has been around a while */
        int32_t  fs_avgfilesize;        /* expected average file size */
        int32_t  fs_avgfpdir;           /* expected # of files per directory */
        int32_t  fs_save_cgsize;        /* save real cg size to use fs_bsize */
        int32_t  fs_sparecon32[26];     /* reserved for future constants */
        uint32_t fs_flags;              /* see FS_ flags below */
+/* back to stuff that has been around a while (again) */
        int32_t  fs_contigsumsize;      /* size of cluster summary array */ 
        int32_t  fs_maxsymlinklen;      /* max length of an internal symlink */
        int32_t  fs_old_inodefmt;       /* format of on-disk inodes */