#!/bin/sh

# This is an example CTDB NFS callout script for Ganesha.  It is based
# on the last version of 60.ganesha shipped with CTDB.  As such, it
# does not try to monitor RPC services that were not monitored by
# 60.ganesha - this might be a useful improvement.  It has also not
# been properly tested.

# You should check your version of NFS Ganesha to see if it ships with
# a newer callout.

# To use this:
#
# * Set CTDB_NFS_CALLOUT in your CTDB configuration to point to (a
#   copy of) this script, making sure it is executable.
#
# * Create a new directory alongside the nfs-checks.d directory, for
#   example nfs-checks-ganesha.d.  Install 20.nfs_ganesha.check and
#   21.nfs.check in this directory.  Symlink to any other check files
#   from nfs-checks.d that should still be used, such as
#   00.portmapper.check.  Set CTDB_NFS_CHECKS_DIR to point to this new
#   directory of check files.
#
# * It is recommended, but not required, to install the grace_period
#   script (usually shipped in a utils package for NFS-Ganesha) to
#   /usr/bin/grace_period

# I (Martin Schwenke) hereby relicense all of my contributions to this
# callout (and, previously, to 60.ganesha) to a license compatible
# with NFS Ganesha (right now this is LGPLv3, but I'm flexible).
# There may be other contributions to be considered for relicensing,
# particularly those in commit 28cbe527d47822f870e8252495ab2a1c8fddd12f.

######################################################################

# Exit on 1st error
set -e

die()
{
	echo "$1"
	exit 1
}

# Shared directory, typically on a cluster filesystem, that will
# contain the NFS-Ganesha state
if [ -z "$CTDB_NFS_SHARED_STATE_DIR" ]; then
	die "$0: CTDB_NFS_SHARED_STATE_DIR is not set"
fi

if [ ! -d "$CTDB_NFS_SHARED_STATE_DIR" ]; then
	t="$CTDB_NFS_SHARED_STATE_DIR" # Readability, below
	die "$0: CTDB_NFS_SHARED_STATE_DIR=${t} not found"
fi

state_fs=$(findmnt -n --target "$CTDB_NFS_SHARED_STATE_DIR" -o FSTYPE)

case "$state_fs" in
glusterfs | gpfs)
	:
	;;
fuse.glusterfs)
	state_fs="glusterfs"
	;;
*)
	d="$CTDB_NFS_SHARED_STATE_DIR"
	die "$0: filesystem type \"${state_fs}\" is not supported for ${d}"
	;;
esac

# Always put NFS-Ganesha state in its own subdirectory
state_dir="${CTDB_NFS_SHARED_STATE_DIR}/ganesha"

# Location of exports file
nfs_exports_file="${CTDB_NFS_EXPORTS_FILE:-/etc/ganesha/ganesha.conf}"

# To change the following, edit the default values below.  Do not set
# these - they aren't configuration variables, just hooks for testing.
nfs_service="${CTDB_NFS_SERVICE:-nfs-ganesha}"
procfs=${PROCFS_PATH:-/proc}

case "$state_fs" in
gpfs)
	GANRECDIR="/var/lib/nfs/ganesha"
	;;
glusterfs)
	host=$(hostname)
	NODESTATEDIR="${state_dir}/${host}"
	GANSTATEDIR="${state_dir}/.noderefs"
	NODESTATELN="$GANSTATEDIR/$host"
	;;
esac

##################################################

usage()
{
	_c=$(basename "$0")
	cat <<EOF
usage: $_c { shutdown | startup }
       $_c { stop | start | check | stats } nfs
       $_c { releaseip | takeip } <iface> <ip> <maskbits>
       $_c { monitor-list-shares }
EOF
	exit 1
}

##################################################
# Basic service stop and start

basic_stop()
{
	case "$1" in
	nfs)
		service "$nfs_service" stop
		;;
	*)
		usage
		;;
	esac
}

basic_start()
{
	case "$1" in
	nfs)
		service "$nfs_service" start
		;;
	*)
		usage
		;;
	esac
}

##################################################
# "stop" and "start" options for restarting

service_stop()
{
	case "$1" in
	nfs)
		basic_stop "nfs"
		;;
	nlockmgr)
		# Do nothing - used by statd-callout
		:
		;;
	*)
		usage
		;;
	esac
}

service_start()
{
	case "$1" in
	nfs)
		basic_start "nfs"
		;;
	nlockmgr)
		# Do nothing - used by statd-callout
		:
		;;
	*)
		usage
		;;
	esac
}

##################################################
# Nitty gritty - monitoring and IP handling

# Check that a symlink exists, create it otherwise.
# Usage: check_ln <TARGET> <LINK>
check_ln()
{
	if [ ! -L "${2}" ]; then
		rm -vrf "${2}"
	else
		_t=$(readlink "${2}")
		if [ "$_t" != "${1}" ]; then
			rm -v "${2}"
		fi
	fi
	# This is not an "else".  It also re-creates the link if it was
	# removed above!
	if [ ! -e "${2}" ]; then
		ln -sfv "${1}" "${2}"
	fi
}

# Return 'active' if the shared filesystem is accessible.
get_cluster_fs_state()
{
	case "$state_fs" in
	gpfs)
		/usr/lpp/mmfs/bin/mmgetstate | awk 'NR == 4 { print $3 }'
		;;
	glusterfs)
		# Since we're past create_ganesha_recdirs(), we're active.
		echo "active"
		;;
	*)
		echo "File system $state_fs not supported"
		exit 1
		;;
	esac
}

create_ganesha_recdirs()
{
	case "$state_fs" in
	gpfs)
		mkdir -vp "$state_dir"
		check_ln "$state_dir" "$GANRECDIR"
		;;
	glusterfs)
		[ -d /var/lib/nfs.backup ] ||
			mv /var/lib/nfs /var/lib/nfs.backup
		check_ln "$NODESTATEDIR" /var/lib/nfs

		mkdir -p "${NODESTATEDIR}/ganesha/v4recov"
		mkdir -p "${NODESTATEDIR}/ganesha/v4old"
		mkdir -p "${NODESTATEDIR}/statd/sm"
		mkdir -p "${NODESTATEDIR}/statd/sm.bak"
		touch "${NODESTATEDIR}/state"
		touch "${NODESTATEDIR}/statd/state"

		mkdir -p "$GANSTATEDIR"
		check_ln "$NODESTATEDIR" "$NODESTATELN"
		for _dir in "${GANSTATEDIR}/"*; do
			# Handle no directories case
			if [ ! -d "$_dir" ]; then
				break
			fi

			_node="${_dir##*/}" # basename
			if [ "${_node}" != "${host}" ]; then
				check_ln "${GANSTATEDIR}/${_node}/ganesha" \
					"${NODESTATEDIR}/ganesha/${_node}"
				check_ln "${GANSTATEDIR}/${_node}/statd" \
					"${NODESTATEDIR}/statd/${_node}"
			fi
		done
		;;
	esac
}

is_ganesha_running()
{
	# Check that NFS Ganesha is running, according to PID file
	_pidfile="/var/run/ganesha/ganesha.pid"
	_ganesha="ganesha.nfsd"
	if ! {
		read -r _pid <"$_pidfile" &&
			[ "$(ps -p "$_pid" -o comm=)" = "$_ganesha" ]
	} >/dev/null 2>&1; then

		return 1
	fi

	return 0
}

service_check()
{
	create_ganesha_recdirs

	# Always succeed if cluster filesystem is not active
	_cluster_fs_state=$(get_cluster_fs_state)
	if [ "$_cluster_fs_state" != "active" ]; then
		return 0
	fi

	if ! is_ganesha_running; then
		echo "ERROR: NFS Ganesha not running according to PID file"
		return 1
	fi

	return 0
}

nfs_stats()
{
	_service="$1"

	case "$_service" in
	nfs)
		timeout -v 5 ganesha_stats | grep '^Total NFSv.* ops:'
		;;
	*)
		# This will never change, so is intentionally
		# unhelpful for avoiding an unhealthy service
		echo "Not implemented" >&2
		exit 1
		;;
	esac
}

#-------------------------------------------------

grace_period()
{
	_arg="$1"

	_gp_status=0
	if [ -x "/usr/bin/grace_period" ]; then
		_out=$(/usr/bin/grace_period "$_arg" 2>&1) ||
			_gp_status=$?
		_down_msg="Error: Can't talk to ganesha service on d-bus"
	else
		_out=$(dbus-send \
			--print-reply --system --dest=org.ganesha.nfsd \
			/org/ganesha/nfsd/admin org.ganesha.nfsd.admin.grace \
			string:"$_arg" 2>&1) ||
			_gp_status=$?
		_down_msg="Error org.freedesktop.DBus.Error.ServiceUnknown"
	fi

	if [ -n "$_out" ]; then
		echo "$_out"
	fi

	if [ $_gp_status -ne 0 ]; then
		# If $_out contains $_down_msg then NFS-Ganesha is
		# either down or is starting, so will be in grace
		# anyway.
		if [ "${_out#*"${_down_msg}"}" != "$_out" ]; then
			return 3 # ESRCH - No such process
		fi
	fi

	return $_gp_status
}

grace_period_if_running()
{
	_arg="$1"

	if ! is_ganesha_running; then
		echo "WARNING: NFS Ganesha not running according to PID file"
		return 0
	fi

	_status=0
	grace_period "$_arg" || _status=$?
	case $_status in
	3)
		# Convert to success
		return 0
		;;
	*)
		return $_status
		;;
	esac
}

nfs_startipreallocate()
{
	grace_period_if_running "0:"
}

nfs_releaseip()
{
	_ip="$2"

	# NFS-Ganesha recovery code only processes items matching $_ip
	grace_period_if_running "2:${_ip}"
}

nfs_takeip()
{
	_ip="$2"

	case "$state_fs" in
	glusterfs)
		check_ln "$NODESTATEDIR" "${GANSTATEDIR}/${_ip}"
		;;
	esac

	grace_period "5:${_ip}"
}

##################################################
# service init startup and final shutdown

nfs_shutdown()
{
	basic_stop "nfs"
}

nfs_startup()
{
	basic_stop "nfs" || true

	create_ganesha_recdirs

	basic_start "nfs"
	_f="${procfs}/sys/net/ipv4/tcp_tw_recycle"
	if [ -f "$_f" ]; then
		echo 1 >"$_f"
	fi
}

##################################################
# list share directories

nfs_monitor_list_shares()
{
	# The 1st sed command prints anything after "Path = ", where
	# Path is matched case-insensitively, and must be on a word
	# boundary.  This also deletes any semicolon-terminated items
	# before Path.  Each output line now starts with a value for
	# Path, but may have other settings after a semicolon.
	_s1='s/.*;*[[:space:]]*\<path\>[[:space:]]*=[[:space:]]*//ip'

	# The 2nd sed command has 2 steps:
	#
	# a. Attempt to match an unquoted value not containing
	#    semicolon or double-quote, followed by an optional
	#    line-terminating semicolon or a semicolon followed by
	#    anything else.  Keep the value and double-quote it.  If
	#    the value was already quoted then the line will be
	#    unchanged.  The pattern space now starts with a
	#    double-quoted value.
	_s2a='s/^\([^";][^";]*\)[[:space:]]*\(;*[[:space:]]*$\|;.*\)/"\1"/'
	# b. Finally, print the contents of double-quotes at the
	#    beginning of the pattern space, discarding anything
	#    that follows.
	_s2b='s/^"\([^"][^"]*\)".*/\1/p'

	sed -n -e "$_s1" "$nfs_exports_file" | sed -n -e "$_s2a" -e "$_s2b"
}

##################################################

nfs_register()
{
	cat <<EOF
shutdown
startup
stop
start
check
stats
startipreallocate
releaseip
takeip
monitor-list-shares
EOF
}

##################################################

action="$1"
shift

case "$action" in
shutdown) nfs_shutdown ;;
startup) nfs_startup ;;
stop) service_stop "$1" ;;
start) service_start "$1" ;;
check) service_check "$1" ;;
stats) nfs_stats "$1" ;;
startipreallocate) nfs_startipreallocate ;;
releaseip) nfs_releaseip "$@" ;;
takeip) nfs_takeip "$@" ;;
monitor-list-shares) nfs_monitor_list_shares ;;
register) nfs_register ;;
monitor-pre | monitor-post)
	# Not required/implemented
	:
	;;
*)
	usage
	;;
esac