Add [-m map] option to zpool_layout

By default the zpool_layout command would always use the slot
number assigned by Linux when generating the zdev.conf file.
This is a reasonable default there are cases when it makes
sense to remap the slot id assigned by Linux using your own
custom mapping.

This commit adds support to zpool_layout to provide a custom
slot mapping file.  The file contains in the first column the
Linux slot it and in the second column the custom slot mapping.
By passing this map file with '-m map' to zpool_config the
mapping will be applied when generating zdev.conf.

Additionally, two sample mapping have been added which reflect
different ways to map the slots in the dragon drawers.

cmd/zpool_layout/zpool_layout

@@ -12,26 +12,30 @@
 # /etc/zfs/zdev.conf file, it allows the by-path naming convertion
 # to change and still keep the simple <channel><rank> naming.
 #
+AWK=${AWK:-/bin/awk}
 CONFIG=${CONFIG:-/etc/zfs/zdev.conf}
 BUSES=( 01 02 03 )
 PORTS=( 4 0 )
 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 )
-TRIGGER=
+TRIGGER="no"
+MAPPING=linux
+
 
 usage() {
 	cat << EOF
-Usage: zpool_layout [-th] [-c file] [-b buses] [-p ports] [-n channels]
-  -c    Alternate config file [default=/etc/zfs/zdev.conf]
-  -b    Enumerate buses [default="01 02 03"]
-  -p    Enumerate ports [default="4 0"]
+Usage: zpool_layout [-th] [-c file] [-b buses] [-p ports] [-n channels] [-m map]
+  -c    Alternate config file [default=${CONFIG}]
+  -b    Enumerate buses [default="${BUSES[*]}"]
+  -p    Enumerate ports [default="${PORTS[*]}"]
   -n    Channel names [default="A..Z"]
-  -t    Trigger and wait for udev to settle [default=no]
+  -t    Trigger and wait for udev to settle [default=${TRIGGER}]
+  -m    Slot mapping [default=${MAPPING}]
   -h    Show this message
 EOF
 	exit 0
 }
 
-while getopts 'c:b:p:n:th' OPTION; do
+while getopts 'c:b:p:n:m:th' OPTION; do
 	case ${OPTION} in
 	c)
 		CONFIG=${OPTARG}
@@ -45,8 +49,11 @@ while getopts 'c:b:p:n:th' OPTION; do
 	n)
 		CHANNELS=(${OPTARG})
 		;;
+	m)
+		MAPPING=`readlink -e ${OPTARG}`
+		;;
 	t)
-		TRIGGER=1
+		TRIGGER=yes
 		;;
 	h)
 		usage
@@ -54,11 +61,31 @@ while getopts 'c:b:p:n:th' OPTION; do
 	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}
 pushd /dev/disk/by-path >/dev/null
 
+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 comment header.
 echo "#"
 echo "# Custom /dev/disk/by-path to /dev/disk/zpool mapping, "
@@ -98,28 +125,34 @@ done
 echo "#"
 
 # Generate mapping from <channel><rank> to by-path name.
-TMP_FILE=`mktemp`
-AWK=${AWK:-/bin/awk}
-
 for (( i=0, k=0; i<${#BUSES[*]}; i++ )); do
 	for (( j=0; j<${#PORTS[*]}; j++, k++ )); do
-		ls *:${BUSES[$i]}:*:${PORTS[$j]}*  2>/dev/null | \
-			grep -v part | sort -n -k7 -t'-'>${TMP_FILE}
+		BYPATH=(`ls *:${BUSES[$i]}:*:${PORTS[$j]}* 2>/dev/null | \
+			grep -v part | sort -n -k7 -t'-' | cut -f1-6 -d'-'`)
+		SLOTS=(`ls *:${BUSES[$i]}:*:${PORTS[$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 ${PORTS[$j]}"
-		${AWK} -F '-' -v ch="${CHANNELS[$k]}" \
-			'{print ch$7 "\t" $0 }' ${TMP_FILE}
+		cat ${TMP_FILE} | sort -n -k2 -t${CHANNELS[$k]}
+		rm -f ${TMP_FILE}
 	done
 done
 
 # Restore stdout from fd #8 and close fd #8.
 exec 1>&8 8>&-
-rm -f ${TMP_FILE}
 popd >/dev/null
 
-if [ ${TRIGGER} ]; then
+if [ ${TRIGGER} = "yes" ]; then
 	udevadm trigger
 	udevadm settle
 fi