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Ok, I've committed the -c3 downgrade support.

Here's an untested rc.d script which should check
and perform the superblock fixes if needed.

I'll probably send mail to tech-kern asking for testers.

Darrin


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Content-Type: application/x-sh
Content-Disposition: attachment; filename=fixsb.sh
Content-Description: rc.d script to check and fix borken superblocks

#!/bin/sh
#
# $NetBSD$
#

# PROVIDE: fixsb
# REQUIRE: localswap
# BEFORE: fsck

. /etc/rc.subr

name="fixsb"
start_cmd="fsck_start"
stop_cmd=":"

fstab=/etc/fstab
#verbose=1

# This shell function extracts the `ffs superblock' of the file
# provided as its argument and tests for the following condition:
# ((fs_magic == FS_UFS1_MAGIC) || fs_magic == FS_UFS1_MAGIC_SWAPPED) &&
# (fs_sbsize == fs_maxbsize) && !(fs_old_flags & FS_FLAGS_UPDATED)
#
# return status is based on status of last filesystem checked:
#   0 for botched superblock
#   1 for filesystem does not appear to be ffs1 filesystem
#   3 for ok fslevel 3 filesystem
#   4 for ok fslevel 4 filesystem
#
# dbj@netbsd.org 2004-04-12T18:15:06-0400
check_part()
{
  # The following are 'cat -v' representations of the ffs1 magic number:
  fsmagicn="^@^A^YT"  # 0x00011954 FS_UFS1_MAGIC
  fsmagics="T^Y^A^@"  # 0x54190100 FS_UFS1_MAGIC_SWAPPED

  # In each of the foo=`dd | dd | cat -v` pipelines below, the first dd command reads in
  # the superblock using block aligned i/o so that it works on a raw character device.
  # The second dd extracts the exact field from the superblock that we with to
  # read.  The data is put through cat -v to avoid having binary data in shell strings.

  if [ ! -z "${verbose}" ]; then
    echo -n "Checking $1 ... " 1>&2
  fi

  # First we extract the superblock magic number field:
  magic="`(dd if="$1" bs=8192 skip=1 count=1 | dd bs=1 count=4 skip=1372 | cat -v) 2> /dev/null`"
  
  # First we check if the magic number is valid either swapped or unswapped:
  if [ "${magic}" = "${fsmagicn}" -o "${magic}" = "${fsmagics}" ]; then

    # Then we read fs_bsize, fs_maxbsize and fs_old_flags fields from the disk:
    bsize="`(dd if="$1" bs=8192 skip=1 count=1 | dd bs=1 count=4 skip=48 | cat -v) 2> /dev/null`"
    maxbsize="`(dd if="$1" bs=8192 skip=1 count=1 | dd bs=1 count=4 skip=860 | cat -v) 2> /dev/null`"
    oldflags="`(dd if="$1" bs=8192 skip=1 count=1 | dd bs=1 count=1 skip=211 | cat -v) 2> /dev/null`"

    if [ ! -z "${debug}" ]; then
      echo "$1: magic=${magic} bsize=${bsize} maxbsize=${maxbsize} oldflags=${oldflags}" 1>&2
    fi

    # Compare the fs_bsize with fs_maxbsize to see if they are the same
    if [ "${bsize}" = "${maxbsize}" ]; then

      # Now check to see if the high bit of fs_old_flags is set.
      case "${oldflags}" in

        # Since the shell variable is the cat -v output, the
        # high bit is indicated in the variable with the prefix M-
        M-*)
        if [ ! -z "${verbose}" ]; then
          echo "file system looks ok at fslevel 4." 1>&2
          return 4
        fi
        ;;

        # if the high bit of fs_old_flags is not set, then there is a problem
        *)
        if [ ! -z "${verbose}" ]; then
          echo "file system has botched superblock upgrade." 1>&2
        fi
        return 0
        ;;
      esac

    fi # [ "${bsize}" = "${maxbsize}" ]

  else # ! [ "${magic}" = "${fsmagicn}" -o "${magic}" = "${fsmagics}" ]
    if [ ! -z "${verbose}" ]; then
      echo "does not appear to be an ffs1 filesystem." 1>&2
    fi
    return 1
  fi  # ! [ "${magic}" = "${fsmagicn}" -o "${magic}" = "${fsmagics}" ]
  if [ ! -z "${verbose}" ]; then
    echo "file system looks ok at fslevel 3." 1>&2
  fi
  return 3
}

# This extracts raw ufs partitions to be fsck'ed from the file ${fstab}
parse_fstab()
{
  for l in 1 2; do
    sed -e '/^#/d' -e 's,/dev/,&r,' "${fstab}" 2> /dev/null | \
      while read d m t o b f err; do
        if [ \( "$t" = "ffs" -o "$t" = "ufs" \) -a "$f" = "$l" ]; then
          echo "$d"
        fi
      done
  done
}

stop_boot()
{
	#	Terminate the process (which may include the parent /etc/rc)
	#	if booting directly to multiuser mode.
	#
	if [ "$autoboot" = yes ]; then
		kill -TERM $$
	fi
	exit 1
}

do_fsck()
{
		# During fsck ignore SIGQUIT

		fsck_ffs ${1+"$@"}
		case $? in
		0)
			;;
		2)
			stop_boot
			;;
		4)
			echo "Rebooting..."
			reboot
			echo "Reboot failed; help!"
			stop_boot
			;;
		8)
			echo "Automatic file system check failed; help!"
			stop_boot
			;;
		12)
			echo "Boot interrupted."
			stop_boot
			;;
		130)
			stop_boot
			;;
		*)
			echo "Unknown error; help!"
			stop_boot
			;;
		esac
}

fsck_start()
{
	if [ -e /fastboot ]; then
		echo "Fast boot: skipping disk checks."
	else
		# During fsck ignore SIGQUIT
		trap : 3

		echo "Checking for botched superblock upgrades:"
		for p in `parse_fstab`; do
			if check_part "$p"; then
				echo "Repairing partition $p"
				do_fsck -p -b 16 -c 4 "$p"
				do_fsck -p -c 3 "$p"
			fi
		done
	fi
}

load_rc_config $name
run_rc_command "$1"

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