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Systemd mount generator: Generate noauto units; add control properties

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This commit refactors the systemd mount generators and makes the
following major changes:

- The generator now generates units for datasets marked canmount=noauto,
  too. These units are NOT WantedBy local-fs.target.
  If there are multiple noauto datasets for a path, no noauto unit will
  be created. Datasets with canmount=on are prioritized.

- Introduces handling of new user properties which are now included in
  the zfs-list.cache files:
    - org.openzfs.systemd:requires:
      List of units to require for this mount unit
    - org.openzfs.systemd:requires-mounts-for:
      List of mounts to require by this mount unit
    - org.openzfs.systemd:before:
      List of units to order after this mount unit
    - org.openzfs.systemd:after:
      List of units to order before this mount unit
    - org.openzfs.systemd:wanted-by:
      List of units to add a Wants dependency on this mount unit to
    - org.openzfs.systemd:required-by:
      List of units to add a Requires dependency on this mount unit to
    - org.openzfs.systemd:nofail:
      Toggles between a wants and a requires dependency.
    - org.openzfs.systemd:ignore:
      Do not generate a mount unit for this dataset.

  Consult the updated man page for detailed documentation.

- Restructures and extends the zfs-mount-generator(8) man page with the
  above properties, information on unit ordering and a license header.

Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Antonio Russo <antonio.e.russo@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: InsanePrawn <insane.prawny@gmail.com>
Closes #9649
This commit is contained in:
InsanePrawn
2020-02-12 18:01:15 +01:00
committed by Brian Behlendorf
parent 9d2f3b7f94
commit ecbbdac799
4 changed files with 386 additions and 46 deletions
Download Patch File Download Diff File Expand all files Collapse all files
etc/systemd/system-generators/zfs-mount-generator.in
+191 -26
View File
@@ -2,6 +2,7 @@
# zfs-mount-generator - generates systemd mount units for zfs
# Copyright (c) 2017 Antonio Russo <antonio.e.russo@gmail.com>
# Copyright (c) 2020 InsanePrawn <insane.prawny@gmail.com>
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
@@ -33,6 +34,35 @@ do_fail() {
exit 1
}
# test if $1 is in space-separated list $2
is_known() {
query="$1"
IFS=' '
# protect against special characters
set -f
for element in $2 ; do
if [ "$query" = "$element" ] ; then
return 0
fi
done
return 1
}
# create dependency on unit file $1
# of type $2, i.e. "wants" or "requires"
# in the target units from space-separated list $3
create_dependencies() {
unitfile="$1"
suffix="$2"
# protect against special characters
set -f
for target in $3 ; do
target_dir="${dest_norm}/${target}.${suffix}/"
mkdir -p "${target_dir}"
ln -s "../${unitfile}" "${target_dir}"
done
}
# see systemd.generator
if [ $# -eq 0 ] ; then
dest_norm="/tmp"
@@ -42,11 +72,6 @@ else
do_fail "zero or three arguments required"
fi
# For ZFSs marked "auto", a dependency is created for local-fs.target. To
# avoid regressions, this dependency is reduced to "wants" rather than
# "requires". **THIS MAY CHANGE**
req_dir="${dest_norm}/local-fs.target.wants/"
mkdir -p "${req_dir}"
# All needed information about each ZFS is available from
# zfs list -H -t filesystem -o <properties>
@@ -74,18 +99,58 @@ process_line() {
p_nbmand="${10}"
p_encroot="${11}"
p_keyloc="${12}"
p_systemd_requires="${13}"
p_systemd_requiresmountsfor="${14}"
p_systemd_before="${15}"
p_systemd_after="${16}"
p_systemd_wantedby="${17}"
p_systemd_requiredby="${18}"
p_systemd_nofail="${19}"
p_systemd_ignore="${20}"
# Minimal pre-requisites to mount a ZFS dataset
# By ordering before zfs-mount.service, we avoid race conditions.
after="zfs-import.target"
before="zfs-mount.service"
wants="zfs-import.target"
requires=""
requiredmounts=""
wantedby=""
requiredby=""
noauto="off"
if [ -n "${p_systemd_after}" ] && \
[ "${p_systemd_after}" != "-" ] ; then
after="${p_systemd_after} ${after}"
fi
if [ -n "${p_systemd_before}" ] && \
[ "${p_systemd_before}" != "-" ] ; then
before="${p_systemd_before} ${before}"
fi
if [ -n "${p_systemd_requires}" ] && \
[ "${p_systemd_requires}" != "-" ] ; then
requires="Requires=${p_systemd_requires}"
fi
if [ -n "${p_systemd_requiresmountsfor}" ] && \
[ "${p_systemd_requiresmountsfor}" != "-" ] ; then
requiredmounts="RequiresMountsFor=${p_systemd_requiresmountsfor}"
fi
# Handle encryption
if [ -n "${p_encroot}" ] &&
[ "${p_encroot}" != "-" ] ; then
keyloadunit="zfs-load-key-$(systemd-escape "${p_encroot}").service"
if [ "${p_encroot}" = "${dataset}" ] ; then
pathdep=""
keymountdep=""
if [ "${p_keyloc%%://*}" = "file" ] ; then
pathdep="RequiresMountsFor='${p_keyloc#file://}'"
if [ -n "${requiredmounts}" ] ; then
keymountdep="${requiredmounts} '${p_keyloc#file://}'"
else
keymountdep="RequiresMountsFor='${p_keyloc#file://}'"
fi
keyloadcmd="@sbindir@/zfs load-key '${dataset}'"
elif [ "${p_keyloc}" = "prompt" ] ; then
keyloadcmd="\
@@ -121,8 +186,10 @@ SourcePath=${cachefile}
Documentation=man:zfs-mount-generator(8)
DefaultDependencies=no
Wants=${wants}
After=${wants}
${pathdep}
After=${after}
Before=${before}
${requires}
${keymountdep}
[Service]
Type=oneshot
@@ -130,23 +197,35 @@ RemainAfterExit=yes
ExecStart=${keyloadcmd}
ExecStop=@sbindir@/zfs unload-key '${dataset}'" > "${dest_norm}/${keyloadunit}"
fi
# Update the dependencies for the mount file to require the
# Update the dependencies for the mount file to want the
# key-loading unit.
wants="${wants} ${keyloadunit}"
after="${after} ${keyloadunit}"
fi
# Prepare the .mount unit
# skip generation of the mount unit if org.openzfs.systemd:ignore is "on"
if [ -n "${p_systemd_ignore}" ] ; then
if [ "${p_systemd_ignore}" = "on" ] ; then
return
elif [ "${p_systemd_ignore}" = "-" ] \
|| [ "${p_systemd_ignore}" = "off" ] ; then
: # This is OK
else
do_fail "invalid org.openzfs.systemd:ignore for ${dataset}"
fi
fi
# Check for canmount=off .
if [ "${p_canmount}" = "off" ] ; then
return
elif [ "${p_canmount}" = "noauto" ] ; then
# Don't let a noauto marked mountpoint block an "auto" marked mountpoint
return
noauto="on"
elif [ "${p_canmount}" = "on" ] ; then
: # This is OK
else
do_fail "invalid canmount"
do_fail "invalid canmount for ${dataset}"
fi
# Check for legacy and blank mountpoints.
@@ -155,7 +234,7 @@ ExecStop=@sbindir@/zfs unload-key '${dataset}'" > "${dest_norm}/${keyloadunit}
elif [ "${p_mountpoint}" = "none" ] ; then
return
elif [ "${p_mountpoint%"${p_mountpoint#?}"}" != "/" ] ; then
do_fail "invalid mountpoint $*"
do_fail "invalid mountpoint for ${dataset}"
fi
# Escape the mountpoint per systemd policy.
@@ -233,15 +312,91 @@ ExecStop=@sbindir@/zfs unload-key '${dataset}'" > "${dest_norm}/${keyloadunit}
"${dataset}" >/dev/kmsg
fi
# If the mountpoint has already been created, give it precedence.
if [ -n "${p_systemd_wantedby}" ] && \
[ "${p_systemd_wantedby}" != "-" ] ; then
noauto="on"
if [ "${p_systemd_wantedby}" = "none" ] ; then
wantedby=""
else
wantedby="${p_systemd_wantedby}"
before="${before} ${wantedby}"
fi
fi
if [ -n "${p_systemd_requiredby}" ] && \
[ "${p_systemd_requiredby}" != "-" ] ; then
noauto="on"
if [ "${p_systemd_requiredby}" = "none" ] ; then
requiredby=""
else
requiredby="${p_systemd_requiredby}"
before="${before} ${requiredby}"
fi
fi
# For datasets with canmount=on, a dependency is created for
# local-fs.target by default. To avoid regressions, this dependency
# is reduced to "wants" rather than "requires" when nofail is not "off".
# **THIS MAY CHANGE**
# noauto=on disables this behavior completely.
if [ "${noauto}" != "on" ] ; then
if [ "${p_systemd_nofail}" = "off" ] ; then
requiredby="local-fs.target"
before="${before} local-fs.target"
else
wantedby="local-fs.target"
if [ "${p_systemd_nofail}" != "on" ] ; then
before="${before} local-fs.target"
fi
fi
fi
# Handle existing files:
# 1. We never overwrite existing files, although we may delete
# files if we're sure they were created by us. (see 5.)
# 2. We handle files differently based on canmount. Units with canmount=on
# always have precedence over noauto. This is enforced by the sort pipe
# in the loop around this function.
# It is important to use $p_canmount and not $noauto here, since we
# sort by canmount while other properties also modify $noauto, e.g.
# org.openzfs.systemd:wanted-by.
# 3. If no unit file exists for a noauto dataset, we create one.
# Additionally, we use $noauto_files to track the unit file names
# (which are the systemd-escaped mountpoints) of all (exclusively)
# noauto datasets that had a file created.
# 4. If the file to be created is found in the tracking variable,
# we do NOT create it.
# 5. If a file exists for a noauto dataset, we check whether the file
# name is in the variable. If it is, we have multiple noauto datasets
# for the same mountpoint. In such cases, we remove the file for safety.
# To avoid further noauto datasets creating a file for this path again,
# we leave the file name in the tracking variable.
if [ -e "${dest_norm}/${mountfile}" ] ; then
printf 'zfs-mount-generator: %s already exists\n' "${mountfile}" \
>/dev/kmsg
if is_known "$mountfile" "$noauto_files" ; then
# if it's in $noauto_files, we must be noauto too. See 2.
printf 'zfs-mount-generator: removing duplicate noauto %s\n' \
"${mountfile}" >/dev/kmsg
# See 5.
rm "${dest_norm}/${mountfile}"
else
# don't log for canmount=noauto
if [ "${p_canmount}" = "on" ] ; then
printf 'zfs-mount-generator: %s already exists. Skipping.\n' \
"${mountfile}" >/dev/kmsg
fi
fi
# file exists; Skip current dataset.
return
else
if is_known "${mountfile}" "${noauto_files}" ; then
# See 4.
return
elif [ "${p_canmount}" = "noauto" ] ; then
noauto_files="${mountfile} ${noauto_files}"
fi
fi
# Create the .mount unit file.
# By ordering before zfs-mount.service, we avoid race conditions.
#
# (Do not use `<<EOF`-style here-documents for this, see warning above)
#
@@ -251,9 +406,12 @@ ExecStop=@sbindir@/zfs unload-key '${dataset}'" > "${dest_norm}/${keyloadunit}
[Unit]
SourcePath=${cachefile}
Documentation=man:zfs-mount-generator(8)
Before=local-fs.target zfs-mount.service
After=${wants}
Before=${before}
After=${after}
Wants=${wants}
${requires}
${requiredmounts}
[Mount]
Where=${p_mountpoint}
@@ -261,13 +419,20 @@ What=${dataset}
Type=zfs
Options=defaults${opts},zfsutil" > "${dest_norm}/${mountfile}"
# Finally, create the appropriate dependency
ln -s "../${mountfile}" "${req_dir}"
# Finally, create the appropriate dependencies
create_dependencies "${mountfile}" "wants" "$wantedby"
create_dependencies "${mountfile}" "requires" "$requiredby"
}
# Feed each line into process_line
for cachefile in "${FSLIST}/"* ; do
while read -r fs ; do
process_line "${fs}"
done < "${cachefile}"
# Sort cachefile's lines by canmount, "on" before "noauto"
# and feed each line into process_line
sort -t "$(printf '\t')" -k 3 -r "${cachefile}" | \
( # subshell is necessary for `sort|while read` and $noauto_files
noauto_files=""
while read -r fs ; do
process_line "${fs}"
done
)
done