[src/netbsd-7]: src/sys/ufs/lfs Pull up following revision(s) (requested by d...

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

details:   https://anonhg.NetBSD.org/src/rev/dcc6457ce6f8
branches:  netbsd-7
changeset: 799533:dcc6457ce6f8
user:      snj <snj%NetBSD.org@localhost>
date:      Tue Aug 04 17:20:58 2015 +0000

description:
Pull up following revision(s) (requested by dholland in ticket #932):
        sys/ufs/lfs/lfs_segment.c: revision 1.247 via patch
Fix catastrophic bug in lfs_rewind() that changed segment numbers
(lfs_curseg/lfs_nextseg in the superblock) using the wrong units.
These fields are for whatever reason the start addresses of segments
(measured in frags) rather than the segment numbers 0..n.
This only apparently affects dumping from a mounted fs; however, it
trashes the fs.
I would really, really like to have a static analysis tool that can
keep track of the units things are measured in, since fs code is full
of conversion macros and the macros are named inscrutable things like
"sntod" whose letters don't necessarily even correspond to the units
they convert. It is surprising that more of these are not wrong.

diffstat:

 sys/ufs/lfs/lfs_segment.c |  8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diffs (36 lines):

diff -r d06e289aaf94 -r dcc6457ce6f8 sys/ufs/lfs/lfs_segment.c
--- a/sys/ufs/lfs/lfs_segment.c Tue Aug 04 17:18:39 2015 +0000
+++ b/sys/ufs/lfs/lfs_segment.c Tue Aug 04 17:20:58 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: lfs_segment.c,v 1.236 2014/03/24 13:42:40 hannken Exp $        */
+/*     $NetBSD: lfs_segment.c,v 1.236.4.1 2015/08/04 17:20:58 snj Exp $        */
 
 /*-
  * Copyright (c) 1999, 2000, 2001, 2002, 2003 The NetBSD Foundation, Inc.
@@ -60,7 +60,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: lfs_segment.c,v 1.236 2014/03/24 13:42:40 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: lfs_segment.c,v 1.236.4.1 2015/08/04 17:20:58 snj Exp $");
 
 #define _VFS_VNODE_PRIVATE     /* XXX: check for VI_MARKER, this has to go */
 
@@ -1702,7 +1702,7 @@
 }
 
 /*
- * Move lfs_offset to a segment earlier than sn.
+ * Move lfs_offset to a segment earlier than newsn.
  */
 int
 lfs_rewind(struct lfs *fs, int newsn)
@@ -1733,7 +1733,7 @@
                panic("lfs_rewind: no clean segments");
        if (newsn >= 0 && sn >= newsn)
                return ENOENT;
-       fs->lfs_nextseg = sn;
+       fs->lfs_nextseg = lfs_sntod(fs, sn);
        lfs_newseg(fs);
        fs->lfs_offset = fs->lfs_curseg;