On Mar 1, 2018, at 11:23 AM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
>
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Implement online fsck for ext* filesystems which live on LVM-managed
> logical volumes. The basic strategy mirrors that of e2croncheck --
> create a snapshot, fsck the snapshot, report whatever errors appear,
> remove snapshot. Unlike e2croncheck, this utility accepts any LVM
> device path, knows about snapshots running out of space, and can call
> fstrim having validated that the fs metadata is ok.
One high-level note - in my lvcheck script, there was an option to disable
background checking if the system was running on a battery:
# determine whether the machine is on AC power
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
log err "Invalid value for AC_UNKNOWN in the config file"
exit 1
fi
}
More comments inline below.
> diff --git a/scrub/e2scrub.in b/scrub/e2scrub.in
> new file mode 100644
> index 0000000..32d11c8
> --- /dev/null
> +++ b/scrub/e2scrub.in
> @@ -0,0 +1,182 @@
> +#!/bin/bash
> +
> +# Copyright (C) 2018 Oracle. All Rights Reserved.
> +#
> +# Author: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> +#
> +# This program is free software; you can redistribute it and/or
> +# modify it under the terms of the GNU General Public License
> +# as published by the Free Software Foundation; either version 2
> +# of the License, or (at your option) any later version.
> +#
> +# This program is distributed in the hope that it would be useful,
> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> +# GNU General Public License for more details.
> +#
> +# You should have received a copy of the GNU General Public License
> +# along with this program; if not, write the Free Software Foundation,
> +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
> +
> +# Automatically check a LVM-managed filesystem online.
> +# We use lvm snapshots to do this, which means that we can only
> +# check filesystems in VGs that have at least 256mb (or so) of
> +# free space.
> +
> +snap_size_mb=256
> +fstrim=0
> +e2fsck_opts=""
> +conffile="@root_sysconfdir@/e2scrub.conf"
> +
> +test -f "${conffile}" && . "${conffile}"
> +
> +print_help() {
> + echo "Usage: $0 [-t] device"
> + echo
> + echo "device must be a LVM-managed block device"
> + echo "-t: Run fstrim if successful."
> +}
> +
> +exitcode() {
> + ret="$1"
> +
> + exit "${ret}"
> +}
> +
> +prog_path() {
> + path="$1"
> + displayname="$2"
> +
> + if ! type -P "${path}" && [ -n "${displayname}" ]; then
> + echo "${displayname}: Command not found."
> + exitcode 8
> + fi
> +}
> +
> +LVS_PROG="$(prog_path "@root_sbindir@/lvs" "lvs")"
> +BLKID_PROG="$(prog_path "@root_sbindir@/blkid" "blkid")"
> +LVCREATE_PROG="$(prog_path "@root_sbindir@/lvcreate" "lvcreate")"
> +LVREMOVE_PROG="$(prog_path "@root_sbindir@/lvremove" "lvremove")"
> +FSTRIM_PROG="$(prog_path "@root_sbindir@/fstrim")"
> +UDEVADM_PROG="$(prog_path "@root_sbindir@/udevadm")"
> +SLEEP_PROG="$(prog_path "@root_bindir@/sleep")"
Rather than hard-coding the pathnames for all of these commands, it would be
a lot easier to just use them by name and set an explicit PATH= to find them.
That avoids the need to do all of the substitutions, and makes the script
much less ugly.
> +while getopts "t" opt; do
> + case "${opt}" in
> + "t") fstrim=1;;
> + *) print_help; exitcode 2;;
> + esac
> +done
> +shift "$((OPTIND - 1))"
> +
> +dev="$1"
> +if [ -z "${dev}" ]; then
> + print_help
> + exitcode 1
> +elif [ ! -b "${dev}" ]; then
> + echo "${dev}: Not a block device?"
> + print_help
> + exitcode 16
> +fi
> +
> +# Make sure this is an LVM device we can snapshot
> +vg="$("${LVS_PROG}" --noheadings -o vg_name "${dev}" 2> /dev/null | sed -e 's/^ //g')"
> +lv="$("${LVS_PROG}" --noheadings -o lv_name "${dev}" 2> /dev/null | sed -e 's/^ //g')"
> +if [ -z "${vg}" ] || [ -z "${lv}" ]; then
> + echo "${dev}: Not a LVM device."
> + exitcode 16
> +fi
> +start_time="$(date +'%Y%m%d%H%M%S')"
> +snap="${lv}.e2scrub"
> +snap_dev="/dev/${vg}/${snap}"
> +fstype="$("${BLKID_PROG}" -p -s TYPE "${dev}" | sed -e 's/^.*TYPE="\(.*\)".*$/\1/g')"
> +
> +case "${fstype}" in
> +"ext2"|"ext3"|"ext4")
> + ;;
> +*)
> + echo "${dev}: Filesystem of type ${fstype} not supported."
> + exitcode 16
> + ;;
> +esac
> +
> +teardown() {
> + # Remove and wait for removal to succeed.
> + "${LVREMOVE_PROG}" -f "${vg}/${snap}" 3>&-
> + while [ -b "${snap_dev}" ] && [ "$?" -eq "5" ]; do
> + /bin/sleep 0.5
> + "${LVREMOVE_PROG}" -f "${vg}/${snap}" 3>&-
> + done
> +}
> +
> +check() {
> + # First we preen the filesystem to recover the journal, then
> + # we see if e2fsck tries any non-optimization repairs. If
> + # either of these two returns a non-zero status (errors fixed
> + # or remaining) then this fs is bad.
> + E2FSCK_FIXES_ONLY=1
> + export E2FSCK_FIXES_ONLY
> + ${DBG} "@root_sbindir@/e2fsck" -p ${e2fsck_opts} "${snap_dev}" || return 1
> + ${DBG} "@root_sbindir@/e2fsck" -fy ${e2fsck_opts} "${snap_dev}" || return
This could run two full e2fsck checks for each filesystem. To recover only
the journal, it would be better to use "e2fsck -E journal_only"?
> +mark_corrupt() {
> + ${DBG} "@root_sbindir@/tune2fs" -C 16000 -T "19000101" "${dev}"
This won't actually do anything if the time/mount-based checks are disabled
(which has been the default for a long time already, not that I agree with it).
You need to add something like "-i 720" to force a check on the filesystem on
the next mount.
Also, this clobbers the mount count unnecessarily.
Finally, using "19000101" has the possibility to underflow in a different
timezone, and is a negative signed timestamp as well (but is stored as unsigned
value) so it may be problematic.
Better to use "19700102" or similar, which is just as likely to cause a check.
> +}
> +
> +setup() {
> + # Create the snapshot, wait for device to appear
> + teardown > /dev/null 2> /dev/null
> + "${LVCREATE_PROG}" -s -L "${snap_size_mb}m" -n "${snap}" "${vg}/${lv}" 3>&-
> + test $? -ne 0 && return 1
> + test -x "${UDEVADM_PROG}" && "${UDEVADM_PROG}" settle
> + return 0
> +}
> +
> +trap "teardown" EXIT INT QUIT TERM
> +if ! setup; then
> + echo "Snapshot of ${dev} FAILED, will not check!"
> + exitcode 1
> +fi
> +
> +# Check and react
> +if check; then
> + echo "Scrub of ${dev} succeeded."
> + mark_clean
> +
> + if [ "${fstrim}" -eq 1 ] && [ -x "${FSTRIM_PROG}" ]; then
> + dir="$(lsblk -o MOUNTPOINT -n "${dev}")"
> + if [ -d "${dir}" ]; then
> + # NB: fstrim fails with snapshot present
> + trap '' EXIT
> + teardown
> + "${FSTRIM_PROG}" -v "${dir}"
> + fi
> + fi
> +
> + ret=0
> +else
> + # fsck failed. Check if the snapshot is invalid; if so, make a
> + # note of that at the end of the log. This isn't necessarily a
> + # failure because the mounted fs could have overflowed the
> + # snapshot with regular disk writes /or/ our repair process
> + # could have done it by repairing too much.
> + #
> + # If it's really corrupt we ought to fsck at next boot.
> + is_invalid="$("${LVS_PROG}" -o lv_snapshot_invalid --noheadings "${snap_dev}")"
> + if [ -n "${is_invalid}" ]; then
> + echo "Scrub of ${dev} FAILED due to invalid snapshot."
> + ret=8
> + else
> + echo "Scrub of ${dev} FAILED! Reboot soon to fsck."
> + mark_corrupt
> + ret=6
> + fi
> +fi
> +
> +exitcode "${ret}"
Cheers, Andreas
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