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Re: forced fsck (again?)



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Andreas Dilger wrote:
> On Jan 23, 2008  09:08 -0500, Theodore Tso wrote:
>> (We could sneek some of that information into the options field of
>> fstab, since the kernel and other programs that parse that field
>> just take what they need and ignore the rest, but.... ick, ick,
>> ick.  :-)
> 
> I agree - adding email to fstab is icky and I wouldn't go there.  I
> don't see a problem with just emailing it to "root@" by default and
> giving the user the option to change it to something else.

Since the email address is not per-filesystem, it's fine by me to put it
into a config file somewhere.  Forcing the interval to be global is
probably also OK, although I wouldn't want to be forced to set the
snapshot size globally.  I do think that fstab is the best place for
per-filesystem options, though.

But it's not too difficult to parse out a custom SNAPSIZE option, and
even have a DEFAULT_SNAPSIZE in the config file if no SNAPSIZE option is
present on any LV, if the script is going to parse fstab anyway.  (Or
should the option's name be lowercase?  Either will work.)

>> Also, I could imagine that a user might not want to check all of
>> the filesystems in fstab.
> 
> Similarly, a config file which disables checking on some LV if
> specified seems reasonable.

That does seem reasonable, but I haven't done it in the script that's
attached.  Maybe support for a SKIP (or skip, or e2check_skip, or
skip_e2check, or whatever) option in fstab's options field?

Regarding the idea of having this support multiple filesystems -- that's
a good idea, I think, but the current script is highly specific to ext2
or ext3.  Use of tune2fs (to reset the last-check time) and dumpe2fs (to
find the last-check time), in particular, will be problematic on other
FSes.  I haven't done that in this script, though it may be possible.

Anyway, here's a second version.  I've changed it to parse up fstab,
and added an option for what to do if AC status can't be determined.
Kernel-style changelog entry, etc., below:

- -------

Create a script to transparently run e2fsck in the background on any LVM
logical volumes listed in /etc/fstab, as long as the machine is on AC
power, and that LV has been last checked more than a configurable number
of days ago.  Also create a configuration file to set various options in
the script.

Signed-Off-By: Bryan Kadzban <bryan kadzban is-a-geek net>
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#!/bin/sh
#
# e2check

# Released under the GNU General Public License, either version 2 or
#  (at your option) any later version.

# Overview:
#
#  Run this from cron each night.  If the machine is on AC power, it
#  will run the checks; otherwise they will all be skipped.  (If the
#  script can't tell whether the machine is on AC power, a setting in
#  the configuration file (/etc/e2check.conf) decides whether it will
#  continue or abort.)
#
#  The script will then decide which filesystems in /etc/fstab are on
#  logical volumes, and can therefore be checked via an LVM snapshot.
#  Each of these filesystems will be queried to find its last check
#  day, and if that was more than $INTERVAL days ago (where INTERVAL
#  is set in the configuration file as well), then the script will
#  take an LVM snapshot of the filesystem and run e2fsck on the
#  snapshot.  The snapshot's size can be set via either the SNAPSIZE
#  option in the options field in /etc/fstab, or the DEFAULT_SNAPSIZE
#  option in /etc/e2check.conf -- but make sure it's set large enough.
#  After e2fsck finishes, the snapshot is destroyed.
#
#  Any filesystem that passes e2fsck will have its last-check time
#  updated (in the real superblock, not the snapshot); any filesystem
#  that fails will send an email notification to a configurable user
#  ($EMAIL).  This $EMAIL setting is optional, but its use is highly
#  recommended, since if any filesystem fails, it will need to be
#  checked manually offline.

function on_ac_power() {
	local any_known=no

	# try sysfs power class first
	if [ -d /sys/class/power_supply ] ; then
		for psu in /sys/class/power_supply/* ; do
			if [ -r "${psu}/type" ] ; then
				type="`cat "${psu}/type"`"

				# ignore batteries
				[ "${type}" = "Battery" ] && continue

				online="`cat "${psu}/online"`"

				[ "${online}" = 1 ] && return 0
				[ "${online}" = 0 ] && any_known=yes
			fi
		done

		[ "${any_known}" = "yes" ] && return 1
	fi

	# else fall back to AC adapters in /proc
	if [ -d /proc/acpi/ac_adapter ] ; then
		for ac in /proc/acpi/ac_adapter/* ; do
			if [ -r "${ac}/state" ] ; then
				grep -q on-line "${ac}/state" && return 0
				grep -q off-line "${ac}/state" && any_known=yes
			elif [ -r "${ac}/status" ] ; then
				grep -q on-line "${ac}/status" && return 0
				grep -q off-line "${ac}/status" && any_known=yes
			fi
		done

		[ "${any_known}" = "yes" ] && return 1
	fi

	if [ "$AC_UNKNOWN" == "CONTINUE" ] ; then
		return 0   # assume on AC power
	elif [ "$AC_UNKNOWN" == "ABORT" ] ; then
		return 1   # assume on battery
	else
		echo "Invalid value for AC_UNKNOWN in the config file" >&2
		exit 1
	fi
}

function check_fs() {
	local vg="$1"
	local lv="$2"
	local opts="$3"
	local snapsize="${DEFAULT_SNAPSIZE}"

	case "$opts" in
		*SNAPSIZE=*)
		# parse out just the SNAPSIZE option's value
		snapsize="${opts##*SNAPSIZE=}"
		snapsize="${snapsize%%,*}"
		;;
	esac   # else leave it at DEFAULT_SNAPSIZE

	[ -z "$snapsize" ] && return 1

	local tmpfile=`mktemp -t e2fsck.log.XXXXXXXXXX`
	trap "rm $tmpfile ; trap - RETURN" RETURN

	local start="$(date +'%Y%m%d%H%M%S')"

	lvcreate -s -L "${snapsize}" -n "${lv}-snap" "${vg}/${lv}"

	if nice logsave -as $tmpfile e2fsck -p -C 0 "/dev/${vg}/${lv}-snap" && \
			nice logsave -as $tmpfile e2fsck -fy -C 0 "/dev/${vg}/${lv}-snap" ; then
		echo 'Background scrubbing succeeded!'
		tune2fs -C 0 -T "${start}" "/dev/${vg}/${lv}"
	else
		echo 'Background scrubbing failed! Reboot to fsck soon!'
		tune2fs -C 16000 -T "19000101" "/dev/${vg}/${lv}"

		if test -n "$EMAIL"; then
			mail -s "E2fsck of /dev/${vg}/${lv} failed!" $EMAIL < $tmpfile
		fi
	fi

	lvremove -f "${vg}/${lv}-snap"
}

set -e

# pull in configuration -- don't bother with a parser, just use the shell's
. /etc/e2check.conf

# check whether the machine is on AC power: if not, skip the e2fsck
on_ac_power || exit 0

# parse up fstab
grep -v '^#' /etc/fstab | grep -v '^$' | awk '$6!=0 {print $1,$3,$4;}' | \
while read FS FSTYPE OPTIONS ; do
	# Use of tune2fs in check_fs, and dumpe2fs below, means we can
	#  only handle ext2/ext3 FSes
	[ "$FSTYPE" != "ext3" || "$FSTYPE" != "ext2" ] && continue

	# get the volume group (or an error message)
	VG="`lvs --noheadings -o vg_name "$FS" 2>&1`"

	# skip non-LVM devices (hopefully LVM VGs don't have spaces)
	[ "`echo "$VG" | awk '{print NF;}'`" -ne 1 ] && continue

	# get the logical volume name
	LV="`lvs --noheadings -o lv_name "$FS"`"

	# get the last check time plus $INTERVAL days
	check_date=`dumpe2fs -h "/dev/${VG}/${LV}" 2>/dev/null | grep 'Last checked:' | \
		sed -e 's/Last checked:[[:space:]]*//'`
	check_day=`date --date="${check_date} $INTERVAL days" +"%Y%m%d"`

	# get today's date, and skip LVs that don't need to be checked yet
	today=`date +"%Y%m%d"`
	[ "$check_day" -gt "$today" ] && continue

	# else, check it
	check_fs "$VG" "$LV" "$OPTIONS"
done

#!/bin/sh

# e2check configuration variables:
#
#  EMAIL
#   Address to send failure notifications to.  If empty,
#   failure notifications will not be sent.
#
#  INTERVAL
#   Days to wait between checks.  All LVs use the same
#   INTERVAL, but the "days since last check" value can
#   be different per LV, since that value is stored in
#   the ext2/ext3 superblock.
#
#  DEFAULT_SNAPSIZE
#   Default snapshot size to use if none is specified
#   in the options field in /etc/fstab (using the custom
#   SNAPSIZE=xxx option) for any LV.  Valid values are
#   anything that the -L option to lvcreate will accept.
#
#  AC_UNKNOWN
#   Whether to run the e2fsck checks if the script can't
#   determine whether the machine is on AC power.  Laptop
#   users will want to set this to ABORT, while server and
#   desktop users will probably want to set this to
#   CONTINUE.  Those are the only two valid values.

EMAIL='root'
INTERVAL=30
DEFAULT_SNAPSIZE=100m
AC_UNKNOWN="ABORT"


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