#!/bin/bash
#
# Direct-Attached Mode
# --------------------
# Set BUSES and HOST_PORTS to match the topology of your system.  As
# each port is enumerated it will be assigned the next channel name.
# The current script enumerates each port on a bus before moving on
# to enumerate the next bus.
#
# Every distribution, version of udev, and type of attached storage
# seems to result in slightly different formatting of the by-path
# name.   For this reason you may need to adjust the parsing below
# to suit your needs.  This is one of the reasons to use a custom
# /etc/zfs/zdev.conf file, it allows the by-path naming convention
# to change and still keep the simple <channel><rank> naming.
#
# SAS-Switch Mode
# -------------------------
# When the host accesses disk via SAS switches the combination of
# bus and port number does not necessarily uniquely identify a
# channel or disk drawer.  In this case we must resort to other
# means to infer the physical topology.  For a single-level network
# (i.e. no switch cascading) we can assign alphabetic channel labels
# based on the switch port number that the drawer is connected to.
# If support for more complex topologies is needed this script will
# need to be customized or replaced.
#
# In SAS-Switch mode (enabled with "-g switch" ) we require that
# udev has been configured to create per-disk symbolic links in
# /dev/disk/by-id of the form
# <label>-<UUID>-switch-port:<X>-slot:<Y>.  <label> is a string that
# depends on the subsystem that created the link and defaults to
# "dm-uuid-mpath" (this prefix is used by multipathd).  <UUID> is a
# unique identifier for the disk typically obtained from the scsi_id
# program.  <X> and <Y> denote the switch port and disk slot
# numbers, respectively, and are typically obtained from sysfs.

AWK=${AWK:-/usr/bin/awk}
CONFIG=${CONFIG:-/etc/zfs/zdev.conf}
BUSES=( 01 02 03 )
HOST_PORTS=( 4 0 )
SWITCH_PORTS=( 0 1 2 3 4 5 6 7 8 9 )
CHANNELS=( A B C D E F G H I J K L M N O P Q R S T U V W X Y Z )
TOPOLOGY="direct"
TRIGGER="no"
MAPPING=linux
LABEL=${LABEL:-"dm-uuid-mpath"}
DEV_DISK_DIR="/dev/disk/by-path"

shopt -s extglob

usage() {
	cat << EOF
Usage: zpool_layout [-th] [-c file] [-b buses] [-o switch_ports]
           [-p host_ports] [-n channels] [-m map] [-l label]
           [-g direct|switch]
  -c    Alternate config file [default=${CONFIG}]
  -b    Enumerate buses [default="${BUSES[*]}"]
  -o    Enumerate switch ports [default="${SWITCH_PORTS[*]}"]
  -p    Enumerate host ports [default="${HOST_PORTS[*]}"]
  -n    Channel names [default="A..Z"]
  -g    Storage network topology [default="${TOPOLOGY}"]
  -t    Trigger and wait for udev to settle [default=${TRIGGER}]
  -l    Prefix of SAS-switch-mode device links [default=${LABEL}]
  -m    Slot mapping [default=${MAPPING}]
  -h    Show this message
EOF
	exit 0
}

while getopts 'c:b:o:p:n:l:m:g:th' OPTION; do
	case ${OPTION} in
	c)
		CONFIG=${OPTARG}
		;;
	b)
		BUSES=(${OPTARG})
		;;
	o)
		SWITCH_PORTS=(${OPTARG})
		;;
	p)
		HOST_PORTS=(${OPTARG})
		;;
	n)
		CHANNELS=(${OPTARG})
		;;
	l)
		LABEL=${OPTARG}
		;;
	m)
		MAPPING=`readlink -e ${OPTARG}`
		;;
	g)
		TOPOLOGY=${OPTARG}
		;;
	t)
		TRIGGER=yes
		;;
	h)
		usage
		;;
	esac
done

# Verify mapping file exists if specified.
# Linux-Slot	Custom-Slot
if [ ${MAPPING} != "linux" ] && [ ! -e ${MAPPING} ]; then
	echo "Error: Mapping file '${MAPPING}' does not exist"
	exit 1
fi

# Save stdout as fd #8, then redirect stdout to the config file.
exec 8>&1
exec >${CONFIG}

map_slot() {
	local LINUX_SLOT=$1
	local MAPPED_SLOT=

	if [ ${MAPPING} = "linux" ]; then
		MAPPED_SLOT=${LINUX_SLOT}
	else
		MAPPED_SLOT=`${AWK} "\\$1 == ${LINUX_SLOT} && !/^#/ \
			{ print \\$2; exit }" $MAPPING`
	fi
	printf "%d" ${MAPPED_SLOT}
}

# Generate host port layout table for comment header.
print_host_port_layout() {
	echo "# ------------------ Host Port Layout ---------------------"
	echo -n "#          "
	for (( i=0; i<${#BUSES[*]}; i++ )); do
		printf "%-8d" ${BUSES[$i]}
	done
	echo

	for (( i=0, k=0; i<${#HOST_PORTS[*]}; i++ )); do
		printf "# Port %-2d  " ${HOST_PORTS[$i]}

		for (( j=0; j<${#BUSES[*]}; j++, k++ )); do
			let k=$j*${#HOST_PORTS[*]}+$i
			printf "%-8s" ${CHANNELS[$k]}
		done
		echo
	done
	echo "#"
}

# Generate SAS switch port layout table for comment header.
print_switch_port_layout() {
	echo "# --------------- SAS Switch Port Layout ------------------"
	echo -n "# Switch Port   "
	for (( i=0; i<${#SWITCH_PORTS[*]}; i++ )); do
		printf "%3d" ${SWITCH_PORTS[$i]}
	done
	echo
	echo -n "# Channel       "
	for (( i=0; i<${#SWITCH_PORTS[*]}; i++ )); do
		printf "%3s" ${CHANNELS[$i]}
	done
	echo
	echo "#"
}

# Generate channel/disk layout table for comment header.
print_channel_layout() {
	pushd ${DEV_DISK_DIR} >/dev/null
	echo "# ----------------- Channel/Disk Layout -------------------"
	echo "# Channel  Disks"
	if [ ${TOPOLOGY} = "switch" ] ; then
		for (( i=0; i<${#SWITCH_PORTS[*]}; i++ )); do
			printf "# %-9s" ${CHANNELS[$i]}
			p=${SWITCH_PORTS[$i]}
			ls ${LABEL}-+([0-9a-f])-switch-port:${p}-slot:+([0-9]) \
				2>/dev/null | cut -f3 -d':' | sort -u -n | \
				xargs | tr ' ' ','
		done
	else
		for (( i=0, k=0; i<${#BUSES[*]}; i++ )); do
			for (( j=0; j<${#HOST_PORTS[*]}; j++, k++ )); do
				printf "# %-9s" ${CHANNELS[$k]}
				ls *:${BUSES[$i]}:*:${HOST_PORTS[$j]}* \
					2>/dev/null | cut -f7 -d'-' | \
					sort -u -n | xargs | tr ' ' ','
			done
		done
	fi
	echo "#"
	popd > /dev/null
}

# Generate mapping from <channel><rank> to by-path name.
map_shortname_to_by_path() {
	pushd ${DEV_DISK_DIR} >/dev/null
	for (( i=0, k=0; i<${#BUSES[*]}; i++ )); do
		for (( j=0; j<${#HOST_PORTS[*]}; j++, k++ )); do
			BYPATH=(`ls *:${BUSES[$i]}:*:${HOST_PORTS[$j]}* \
				2>/dev/null | grep -v part | \
				sort -n -k7 -t'-' | cut -f1-6 -d'-'`)
			SLOTS=(`ls *:${BUSES[$i]}:*:${HOST_PORTS[$j]}* \
				2>/dev/null | grep -v part | \
				sort -n -k7 -t'-' | cut -f7 -d'-'`)
			TMP_FILE=`mktemp`

			for (( l=0; l<${#SLOTS[*]}; l++ )); do
				MAPPED_SLOT=`map_slot ${SLOTS[$l]}`
				printf "%s%d\t%s-%d\n" \
					${CHANNELS[$k]} ${MAPPED_SLOT} \
					${BYPATH[$l]} ${SLOTS[$l]} >>${TMP_FILE}
			done

			echo
			echo -n "# Channel ${CHANNELS[$k]}, "
			echo "Bus ${BUSES[$i]}, Port ${HOST_PORTS[$j]}"
			cat ${TMP_FILE} | sort -n -k2 -t${CHANNELS[$k]}
			rm -f ${TMP_FILE}
		done
	done
	popd >/dev/null
}

# Generate mapping from <channel><rank> to by-id name.
map_shortname_to_by_id() {
	pushd ${DEV_DISK_DIR} >/dev/null
	for (( i=0; i<${#SWITCH_PORTS[*]}; i++ )); do
		p=${SWITCH_PORTS[$i]}
		BYID=(`ls ${LABEL}-+([0-9a-f])-switch-port:${p}-slot:+([0-9]) \
			2>/dev/null | grep -v part | sort -k3n -t':' | \
			cut -f1-2 -d':'`)
		SLOTS=(`ls ${LABEL}-+([0-9a-f])-switch-port:${p}-slot:+([0-9]) \
			2>/dev/null | grep -v part | sort -k3n -t':' | \
			cut -f3 -d':'`)
		TMP_FILE=`mktemp`

		for (( l=0; l<${#SLOTS[*]}; l++ )); do
			MAPPED_SLOT=`map_slot ${SLOTS[$l]}`
			printf "%s%d\t%s:%d\n" \
				${CHANNELS[$i]} ${MAPPED_SLOT} ${BYID[$l]} \
				${SLOTS[$l]} >>${TMP_FILE}
		done

		echo
		echo -n "# Channel ${CHANNELS[$i]}, "
		echo "SAS Switch Port ${SWITCH_PORTS[$i]}"
		cat ${TMP_FILE} | sort -n -k2 -t${CHANNELS[$i]}
		rm -f ${TMP_FILE}
	done
	popd > /dev/null
}

# Generate comment header.
echo "#"
echo "# Custom ${DEV_DISK_DIR}  to /dev/disk/zpool mapping, "
echo "# based of the following physical cable layout."
echo "#"

case ${TOPOLOGY} in
	direct)
		print_host_port_layout
		print_channel_layout
		map_shortname_to_by_path
		;;
	switch)
		DEV_DISK_DIR="/dev/disk/by-id"
		print_switch_port_layout
		print_channel_layout
		map_shortname_to_by_id
		;;
esac

# Restore stdout from fd #8 and close fd #8.
exec 1>&8 8>&-

if [ ${TRIGGER} = "yes" ]; then
	udevadm trigger --action=change --subsystem-match=block
	udevadm settle
fi

exit 0