From 38528476bf0b64e7462a1141ff73d016a94f3471 Mon Sep 17 00:00:00 2001 From: Pavel Zakharov Date: Wed, 17 Jul 2019 18:33:05 -0400 Subject: [PATCH] New service that waits on zvol links to be created MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The zfs-volume-wait.service scans existing zvols and waits for their links under /dev to be created. Any service that depends on zvol links to be there should add a dependency on zfs-volumes.target. By default, this target is not enabled. Reviewed-by: Fabian Grünbichler Reviewed-by: Antonio Russo Reviewed-by: Richard Laager Reviewed-by: loli10K Reviewed-by: John Gallagher Reviewed-by: George Wilson Reviewed-by: Brian Behlendorf Signed-off-by: Pavel Zakharov Closes #8975 --- cmd/Makefile.am | 2 +- cmd/zvol_wait/Makefile.am | 1 + cmd/zvol_wait/zvol_wait | 93 +++++++++++++++++++ configure.ac | 1 + etc/systemd/system/50-zfs.preset.in | 1 + etc/systemd/system/Makefile.am | 4 + etc/systemd/system/zfs-volume-wait.service.in | 13 +++ etc/systemd/system/zfs-volumes.target.in | 7 ++ man/man1/Makefile.am | 2 +- man/man1/zvol_wait.1 | 21 +++++ rpm/generic/zfs.spec.in | 3 +- 11 files changed, 145 insertions(+), 3 deletions(-) create mode 100644 cmd/zvol_wait/Makefile.am create mode 100755 cmd/zvol_wait/zvol_wait create mode 100644 etc/systemd/system/zfs-volume-wait.service.in create mode 100644 etc/systemd/system/zfs-volumes.target.in create mode 100644 man/man1/zvol_wait.1 diff --git a/cmd/Makefile.am b/cmd/Makefile.am index 0d990789b..88609e455 100644 --- a/cmd/Makefile.am +++ b/cmd/Makefile.am @@ -5,4 +5,4 @@ if USING_PYTHON SUBDIRS += arcstat arc_summary dbufstat endif -SUBDIRS += mount_zfs zed zvol_id +SUBDIRS += mount_zfs zed zvol_id zvol_wait diff --git a/cmd/zvol_wait/Makefile.am b/cmd/zvol_wait/Makefile.am new file mode 100644 index 000000000..564031c97 --- /dev/null +++ b/cmd/zvol_wait/Makefile.am @@ -0,0 +1 @@ +dist_bin_SCRIPTS = zvol_wait diff --git a/cmd/zvol_wait/zvol_wait b/cmd/zvol_wait/zvol_wait new file mode 100755 index 000000000..d512be41b --- /dev/null +++ b/cmd/zvol_wait/zvol_wait @@ -0,0 +1,93 @@ +#!/bin/sh + +count_zvols() { + if [ -z "$zvols" ]; then + echo 0 + else + echo "$zvols" | wc -l + fi +} + +filter_out_zvols_with_links() { + while read -r zvol; do + if [ ! -L "/dev/zvol/$zvol" ]; then + echo "$zvol" + fi + done +} + +filter_out_deleted_zvols() { + while read -r zvol; do + if zfs list "$zvol" >/dev/null 2>&1; then + echo "$zvol" + fi + done +} + +list_zvols() { + zfs list -t volume -H -o name,volmode | while read -r zvol_line; do + name=$(echo "$zvol_line" | awk '{print $1}') + volmode=$(echo "$zvol_line" | awk '{print $2}') + # /dev links are not created for zvols with volmode = "none". + [ "$volmode" = "none" ] || echo "$name" + done +} + +zvols=$(list_zvols) +zvols_count=$(count_zvols) +if [ "$zvols_count" -eq 0 ]; then + echo "No zvols found, nothing to do." + exit 0 +fi + +echo "Testing $zvols_count zvol links" + +outer_loop=0 +while [ "$outer_loop" -lt 20 ]; do + outer_loop=$((outer_loop + 1)) + + old_zvols_count=$(count_zvols) + + inner_loop=0 + while [ "$inner_loop" -lt 30 ]; do + inner_loop=$((inner_loop + 1)) + + zvols="$(echo "$zvols" | filter_out_zvols_with_links)" + + zvols_count=$(count_zvols) + if [ "$zvols_count" -eq 0 ]; then + echo "All zvol links are now present." + exit 0 + fi + sleep 1 + done + + echo "Still waiting on $zvols_count zvol links ..." + # + # Although zvols should normally not be deleted at boot time, + # if that is the case then their links will be missing and + # we would stall. + # + if [ "$old_zvols_count" -eq "$zvols_count" ]; then + echo "No progress since last loop." + echo "Checking if any zvols were deleted." + + zvols=$(echo "$zvols" | filter_out_deleted_zvols) + zvols_count=$(count_zvols) + + if [ "$old_zvols_count" -ne "$zvols_count" ]; then + echo "$((old_zvols_count - zvols_count)) zvol(s) deleted." + fi + + if [ "$zvols_count" -ne 0 ]; then + echo "Remaining zvols:" + echo "$zvols" + else + echo "All zvol links are now present." + exit 0 + fi + fi +done + +echo "Timed out waiting on zvol links" +exit 1 diff --git a/configure.ac b/configure.ac index e8592ffb1..a3ac134ff 100644 --- a/configure.ac +++ b/configure.ac @@ -123,6 +123,7 @@ AC_CONFIG_FILES([ cmd/zed/zed.d/Makefile cmd/raidz_test/Makefile cmd/zgenhostid/Makefile + cmd/zvol_wait/Makefile contrib/Makefile contrib/bash_completion.d/Makefile contrib/dracut/Makefile diff --git a/etc/systemd/system/50-zfs.preset.in b/etc/systemd/system/50-zfs.preset.in index 884a69b5b..e4056a92c 100644 --- a/etc/systemd/system/50-zfs.preset.in +++ b/etc/systemd/system/50-zfs.preset.in @@ -5,4 +5,5 @@ enable zfs-import.target enable zfs-mount.service enable zfs-share.service enable zfs-zed.service +enable zfs-volume-wait.service enable zfs.target diff --git a/etc/systemd/system/Makefile.am b/etc/systemd/system/Makefile.am index 1586209ca..9249f15eb 100644 --- a/etc/systemd/system/Makefile.am +++ b/etc/systemd/system/Makefile.am @@ -7,7 +7,9 @@ systemdunit_DATA = \ zfs-import-scan.service \ zfs-mount.service \ zfs-share.service \ + zfs-volume-wait.service \ zfs-import.target \ + zfs-volumes.target \ zfs.target EXTRA_DIST = \ @@ -17,6 +19,8 @@ EXTRA_DIST = \ $(top_srcdir)/etc/systemd/system/zfs-mount.service.in \ $(top_srcdir)/etc/systemd/system/zfs-share.service.in \ $(top_srcdir)/etc/systemd/system/zfs-import.target.in \ + $(top_srcdir)/etc/systemd/system/zfs-volume-wait.service.in \ + $(top_srcdir)/etc/systemd/system/zfs-volumes.target.in \ $(top_srcdir)/etc/systemd/system/zfs.target.in \ $(top_srcdir)/etc/systemd/system/50-zfs.preset.in diff --git a/etc/systemd/system/zfs-volume-wait.service.in b/etc/systemd/system/zfs-volume-wait.service.in new file mode 100644 index 000000000..75bd9fcdd --- /dev/null +++ b/etc/systemd/system/zfs-volume-wait.service.in @@ -0,0 +1,13 @@ +[Unit] +Description=Wait for ZFS Volume (zvol) links in /dev +DefaultDependencies=no +After=systemd-udev-settle.service +After=zfs-import.target + +[Service] +Type=oneshot +RemainAfterExit=yes +ExecStart=@bindir@/zvol_wait + +[Install] +WantedBy=zfs-volumes.target diff --git a/etc/systemd/system/zfs-volumes.target.in b/etc/systemd/system/zfs-volumes.target.in new file mode 100644 index 000000000..5cb9a10f4 --- /dev/null +++ b/etc/systemd/system/zfs-volumes.target.in @@ -0,0 +1,7 @@ +[Unit] +Description=ZFS volumes are ready +After=zfs-volume-wait.service +Requires=zfs-volume-wait.service + +[Install] +WantedBy=zfs.target diff --git a/man/man1/Makefile.am b/man/man1/Makefile.am index bd78be145..2af917fa5 100644 --- a/man/man1/Makefile.am +++ b/man/man1/Makefile.am @@ -1,4 +1,4 @@ -dist_man_MANS = zhack.1 ztest.1 raidz_test.1 +dist_man_MANS = zhack.1 ztest.1 raidz_test.1 zvol_wait.1 EXTRA_DIST = cstyle.1 install-data-local: diff --git a/man/man1/zvol_wait.1 b/man/man1/zvol_wait.1 new file mode 100644 index 000000000..0366da537 --- /dev/null +++ b/man/man1/zvol_wait.1 @@ -0,0 +1,21 @@ +.Dd July 5, 2019 +.Dt ZVOL_WAIT 1 SMM +.Os Linux +.Sh NAME +.Nm zvol_wait +.Nd Wait for ZFS volume links in +.Em /dev +to be created. +.Sh SYNOPSIS +.Nm +.Sh DESCRIPTION +When a ZFS pool is imported, ZFS will register each ZFS volume +(zvol) as a disk device with the system. As the disks are registered, +.Xr \fBudev 7\fR +will asynchronously create symlinks under +.Em /dev/zvol +using the zvol's name. +.Nm +will wait for all those symlinks to be created before returning. +.Sh SEE ALSO +.Xr \fBudev 7\fR diff --git a/rpm/generic/zfs.spec.in b/rpm/generic/zfs.spec.in index 0864a72a1..4fdf7bb69 100644 --- a/rpm/generic/zfs.spec.in +++ b/rpm/generic/zfs.spec.in @@ -322,7 +322,7 @@ image which is ZFS aware. %if 0%{?_systemd} %define systemd --enable-systemd --with-systemdunitdir=%{_unitdir} --with-systemdpresetdir=%{_presetdir} --with-systemdmodulesloaddir=%{_modulesloaddir} --with-systemdgeneratordir=%{_systemdgeneratordir} --disable-sysvinit - %define systemd_svcs zfs-import-cache.service zfs-import-scan.service zfs-mount.service zfs-share.service zfs-zed.service zfs.target zfs-import.target + %define systemd_svcs zfs-import-cache.service zfs-import-scan.service zfs-mount.service zfs-share.service zfs-zed.service zfs.target zfs-import.target zfs-volume-wait.service zfs-volumes.target %else %define systemd --enable-sysvinit --disable-systemd %endif @@ -419,6 +419,7 @@ systemctl --system daemon-reload >/dev/null || true %{_sbindir}/* %{_bindir}/raidz_test %{_bindir}/zgenhostid +%{_bindir}/zvol_wait # Optional Python 2/3 scripts %{_bindir}/arc_summary %{_bindir}/arcstat