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Subject: [PATCH v2 4/4] nfs-utils: Update nfs4_unique_id module parameter
 from the nfs.conf value
From:   Alice Mitchell <ajmitchell@redhat.com>
To:     Linux NFS Mailing list <linux-nfs@vger.kernel.org>
Cc:     Steve Dickson <steved@redhat.com>
Date:   Thu, 16 Jul 2020 14:56:36 +0100
In-Reply-To: <c6571aecaaeff95681421c1684814a823b8a087e.camel@redhat.com>
References: <c6571aecaaeff95681421c1684814a823b8a087e.camel@redhat.com>
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This reintroduces the nfs-config.service in order to ensure
that values are taken from nfs.conf and fed to the kernel
module if it is loaded and modprobe.d config incase it is not

Signed-off-by: Alice Mitchell <ajmitchell@redhat.com>
---
 nfs.conf                      |  1 +
 systemd/Makefile.am           |  3 +++
 systemd/README                |  5 +++++
 systemd/nfs-conf-export.sh    | 28 ++++++++++++++++++++++++++++
 systemd/nfs-config.service.in | 17 +++++++++++++++++
 systemd/nfs.conf.man          | 12 +++++++++++-
 6 files changed, 65 insertions(+), 1 deletion(-)
 create mode 100755 systemd/nfs-conf-export.sh
 create mode 100644 systemd/nfs-config.service.in

diff --git a/nfs.conf b/nfs.conf
index 186a5b19..8bb41227 100644
--- a/nfs.conf
+++ b/nfs.conf
@@ -4,6 +4,7 @@
 #
 [general]
 # pipefs-directory=/var/lib/nfs/rpc_pipefs
+# nfs4_unique_id = ${machine-id}
 #
 [exports]
 # rootdir=/export
diff --git a/systemd/Makefile.am b/systemd/Makefile.am
index 75cdd9f5..51acdc3f 100644
--- a/systemd/Makefile.am
+++ b/systemd/Makefile.am
@@ -9,6 +9,7 @@ unit_files =  \
     nfs-mountd.service \
     nfs-server.service \
     nfs-utils.service \
+    nfs-config.service \
     rpc-statd-notify.service \
     rpc-statd.service \
     \
@@ -69,4 +70,6 @@ genexec_PROGRAMS = nfs-server-generator rpc-pipefs-generator
 install-data-hook: $(unit_files)
 	mkdir -p $(DESTDIR)/$(unitdir)
 	cp $(unit_files) $(DESTDIR)/$(unitdir)
+	mkdir -p $(DESTDIR)/$(libexecdir)/nfs-utils
+	install  nfs-conf-export.sh $(DESTDIR)/$(libexecdir)/nfs-utils/
 endif
diff --git a/systemd/README b/systemd/README
index da23d6f6..56108b10 100644
--- a/systemd/README
+++ b/systemd/README
@@ -28,6 +28,11 @@ by a suitable 'preset' setting:
     If enabled, then blkmapd will be run when nfs-client.target is
     started.
 
+ nfs-config.service
+    Invoked by nfs-client.target to export values from nfs.conf to
+    any kernel modules that require it, such as setting nfs4_unique_id
+    for the nfs client modules
+
 Another special unit is "nfs-utils.service".  This doesn't really do
 anything, but exists so that other units may declare themselves as
 "PartOf" nfs-utils.service.
diff --git a/systemd/nfs-conf-export.sh b/systemd/nfs-conf-export.sh
new file mode 100755
index 00000000..486e8df9
--- /dev/null
+++ b/systemd/nfs-conf-export.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+#
+# This script pulls values out of /etc/nfs.conf and configures
+# the appropriate kernel modules which cannot read it directly
+
+NFSMOD=/sys/module/nfs/parameters/nfs4_unique_id
+NFSPROBE=/etc/modprobe.d/nfs.conf
+
+# Now read the values from nfs.conf
+MACHINEID=`nfsconf --get general nfs4_unique_id`
+if [ $? -ne 0 ] || [ "$MACHINEID" == "" ]
+then
+# No config vaue found, assume blank
+MACHINEID=""
+fi
+
+# Kernel module is already loaded, update the live one
+if [ -e $NFSMOD ]; then
+echo -n "$MACHINEID" >> $NFSMOD
+fi
+
+# Rewrite the modprobe file for next reboot
+echo "# This file is overwritten by systemd nfs-config.service" > $NFSPROBE
+echo "# with values taken from /etc/nfs.conf" >> $NFSPROBE
+echo "# Do not hand modify" >> $NFSPROBE
+echo "options nfs nfs4_unique_id=\"$MACHINEID\"" >> $NFSPROBE
+
+echo "Set to: $MACHINEID"
diff --git a/systemd/nfs-config.service.in b/systemd/nfs-config.service.in
new file mode 100644
index 00000000..c5ef1024
--- /dev/null
+++ b/systemd/nfs-config.service.in
@@ -0,0 +1,17 @@
+[Unit]
+Description=Preprocess NFS configuration
+PartOf=nfs-client.target
+After=nfs-client.target
+DefaultDependencies=no
+
+[Service]
+Type=oneshot
+# This service needs to run any time any nfs service
+# is started, so changes to local config files get
+# incorporated.  Having "RemainAfterExit=no" (the default)
+# ensures this happens.
+RemainAfterExit=no
+ExecStart=@_libexecdir@/nfs-utils/nfs-conf-export.sh
+
+[Install]
+WantedBy=nfs-client.target
diff --git a/systemd/nfs.conf.man b/systemd/nfs.conf.man
index 28dbaa99..fb9d2dab 100644
--- a/systemd/nfs.conf.man
+++ b/systemd/nfs.conf.man
@@ -101,8 +101,11 @@ When a list is given, the members should be comma-separated.
 .TP
 .B general
 Recognized values:
-.BR pipefs-directory .
+.BR pipefs-directory ,
+.BR nfs4_unique_id .
 
+For 
+.BR pipefs-directory
 See
 .BR blkmapd (8),
 .BR rpc.idmapd (8),
@@ -110,6 +113,13 @@ and
 .BR rpc.gssd (8)
 for details.
 
+The
+.BR nfs4_unique_id
+value is used by the NFS4 client when identifying itself to servers and
+can be used to ensure that this value is unique when the local system name
+perhaps is not. For full details please refer to the kernel Documentation
+.I filesystems/nfs/nfs.txt
+
 .TP
 .B exports
 Recognized values:
-- 
2.18.1