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Date: Tue, 19 Mar 2019 11:58:24 +0100
From: Lukas Czerner <lczerner@...hat.com>
To: "Darrick J. Wong" <darrick.wong@...cle.com>
Cc: Theodore Ts'o <tytso@....edu>, linux-ext4@...r.kernel.org,
Paul Menzel <pmenzel@...gen.mpg.de>
Subject: Re: [PATCH] e2scrub_all: refactor device probe loop
On Mon, Mar 18, 2019 at 05:17:32PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@...cle.com>
>
> Paul Menzel reported that the e2scrub_all reaper service that runs at
> startup takes a long time to run, and Ted T'so pointed out that we could
> do a lot less work by using lvs as the outer loop in the ext4 filesystem
> probe function so that we only have to lsblk the lvm devices containing
> ext4 filesystems.
>
> Therefore, refactor the loops to put lvs first, which should boost speed
> a bit.
>
> Reported-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> ---
> scrub/e2scrub_all.in | 51 ++++++++++++++++++++++++++++++++++++--------------
> 1 file changed, 37 insertions(+), 14 deletions(-)
>
> diff --git a/scrub/e2scrub_all.in b/scrub/e2scrub_all.in
> index 23d122d25..41420d03d 100644
> --- a/scrub/e2scrub_all.in
> +++ b/scrub/e2scrub_all.in
> @@ -19,6 +19,7 @@
> # Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
>
> scrub_all=0
> +reap=0
> conffile="@root_sysconfdir@...scrub.conf"
>
> test -f "${conffile}" && . "${conffile}"
> @@ -61,7 +62,7 @@ exitcode() {
> while getopts "ArV" opt; do
> case "${opt}" in
> "A") scrub_all=1;;
> - "r") scrub_args="${scrub_args} -r";;
> + "r") scrub_args="${scrub_args} -r"; reap=1;;
> "V") print_version; exitcode 0;;
> *) print_help; exitcode 2;;
> esac
> @@ -69,27 +70,27 @@ done
> shift "$((OPTIND - 1))"
>
> # Find scrub targets, make sure we only do this once.
> -ls_scrub_targets() {
> - lsblk -o NAME,FSTYPE,MOUNTPOINT -p -P -n | while read vars; do
> +ls_scan_targets() {
> + lvs --name-prefixes -o vg_name,lv_name,lv_path \
> + -S lv_active=active,lv_role=public --noheadings | \
You're not using vg_name, nor lv_name so you can drop it maybe ? Also
you're missing lv_role since you're checking it later, however you can
do this instead
-S lv_active=active,lv_role=public -S lv_role!=snapshot
so you only need to ask for lv_path
> + while read vars; do
> eval "${vars}"
> + eval "$(lsblk -o NAME,FSTYPE,MOUNTPOINT -p -P -n "${LVM2_LV_PATH}")"
Now that you only have one lv filed you can maybe pass this directly to
the lsblk ?
This looks funny but works fine for me :)
lsblk -o MOUNTPOINT,NAME,FSTYPE -p -n `lvs -o lv_path -S lv_active=active,lv_role=public -S lv_role!=snapshot --noheadings` | grep 'ext[234]' | awk '{print $1}'
if you only want mounted file systems than you just add
| grep -v -E '^/dev/'
>
> - # Skip non-ext[234]
> + # Skip unless ext*
> case "${FSTYPE}" in
> - ext[234]) ;;
> - *) continue;;
> + ext*) ;;
> + *) continue;;
> esac
>
> + # Don't run against a snapshot ever
> + echo "${LVM2_LV_ROLE}" | grep -q "snapshot" && continue
> +
> # Skip unmounted filesystems unless -A
> if [ "${scrub_all}" -eq 0 ] && [ -z "${MOUNTPOINT}" ]; then
> continue;
> fi
>
> - # Skip non-lvm devices and lvm snapshots
> - lvm_vars="$(lvs --nameprefixes -o vg_name,lv_name,lv_role --noheadings "${NAME}" 2> /dev/null)"
> - test $? -ne 0 && continue
> - eval "${lvm_vars}"
> - echo "${LVM2_LV_ROLE}" | grep -q "snapshot" && continue
> -
> if [ -n "${MOUNTPOINT}" ]; then
> echo "${MOUNTPOINT}"
> else
> @@ -98,6 +99,28 @@ ls_scrub_targets() {
> done | sort | uniq
> }
>
> +# Find leftover scrub snapshots
> +ls_reap_targets() {
> + lvs --name-prefixes -o vg_name,lv_name,lv_path,origin \
You only seem to be using lv_name and lv_path ?
also I think you can do this:
lvs -o lv_path -S lv_role=snapshot -S lv_name=~\(e2scrub$\) --noheadings
Also since you only ask for one field I tihnk it's already sorted so no
need to sort, or add -O
-Lukas
> + -S lv_role=snapshot --noheadings | while read vars; do
> + eval "${vars}"
> +
> + # Filter out anything except our snapshots
> + case "${LVM2_LV_NAME}" in
> + *.e2scrub) echo "${LVM2_LV_PATH}";;
> + esac
> + done | sort | uniq
> +}
> +
> +# Figure out what we're targeting
> +ls_targets() {
> + if [ "${reap}" -eq 1 ]; then
> + ls_reap_targets
> + else
> + ls_scan_targets
> + fi
> +}
> +
> # systemd doesn't know to do path escaping on the instance variable we pass
> # to the e2scrub service, which breaks things if there is a dash in the path
> # name. Therefore, do the path escaping ourselves if needed.
> @@ -118,10 +141,10 @@ escape_path_for_systemd() {
>
> # Scrub any mounted fs on lvm by creating a snapshot and fscking that.
> stdin="$(realpath /dev/stdin)"
> -ls_scrub_targets | while read tgt; do
> +ls_targets | while read tgt; do
> # If we're not reaping and systemd is present, try invoking the
> # systemd service.
> - if [ -z "${scrub_args}" ] && type systemctl > /dev/null 2>&1; then
> + if [ "${reap}" -ne 1 ] && type systemctl > /dev/null 2>&1; then
> tgt_esc="$(escape_path_for_systemd "${tgt}")"
> ${DBG} systemctl start "e2scrub@...gt_esc}" 2> /dev/null < "${stdin}"
> res=$?
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