btrfs_device_report

#!/usr/bin/env bash

: '
Author: Mark McBride <mark@markmcb.com>

Description: This script provides a concise view of "btrfs device stats" and combines
it with information from lsblk to associate the /btrfs/path, the /dev/sdX and the 
/dev/mapper paths. While it should generally be portable on Linux machines
it has not been extensively tested, so some hacking may be required.

IMPORTANT: This script requires root priviledges as they are required by the btrfs 
command to access device information. Running without root priviledges will exit with
an error.
'

if [[ $EUID -ne 0 ]]; then
	echo "This script requires root priviledges."
	exit 2
fi

# process cli args
OPTIND=1 # Reset in case getopts has been used previously in the shell.
verbose=0
optstring="vh?"

while getopts $optstring opt; do
	case "$opt" in
	v)  verbose=1
		;;
	esac
done

# get paths
paths=( `df -T | grep btrfs | grep -v "/var/lib" | sed -E "s/.*% //" | tr '\n' ' '` )
longest_path=10

# get lsblk info, make it flat per disk
lsblk=$(lsblk -n -i -p -o NAME,TYPE,UUID | while read line; do printf "%s" "$([[ "${line}" == *"disk"* ]] && printf $'\n'"%s" "$line" || printf "%s " "$line")"; done)

# get longest path name
longest_mapping=7    # like /dev/mapper/whatever
for path in "${paths[@]}"
do
	this_path_length=$( echo -n ${path} | wc -m )
	if (( ${this_path_length} > ${longest_path} )); then
		longest_path=$this_path_length
	fi

	# get longest device name
	# loop through all stats output lines
	rawstats=$(btrfs device stats ${path})
	while IFS="" read -r p || [ -n "$p" ]
	do
		this_mapping_length=$( echo -n $p | sed -E "s/\[(.*)\].*/\1/" | wc -m )
		if (( ${this_mapping_length} > ${longest_mapping} )); then
			longest_mapping=$this_mapping_length
		fi
	done <<< ${rawstats}
done

longest_device=7 # like sda
while IFS="" read -r p || [ -n "$p" ]
do
	if [ "${verbose}" == "0" ]; then
		this_device_length=$( echo -n $p | awk '{printf $1}' | sed -E "s/\/dev\///" | wc -m )
	else
		this_device_length=$( echo -n $p | awk '{printf $1}' | wc -m )
	fi
	if (( ${this_device_length} > ${longest_device} )); then
		longest_device=$this_device_length
	fi
done <<< ${lsblk}

# show the first n characters of the device name
if [ "${verbose}" == "0" ]; then
	mapping_length='9'
else
	mapping_length="${longest_mapping}"
fi

# print header
if [ "${verbose}" == "0" ]; then
	valueheaders="WRFCG"
else
	valueheaders='Write IO   Read IO  Flush IO   Corrupt  Generate'
fi
printf "%-${longest_path}s  %-${mapping_length}s  %-${longest_device}s  %s\n" "BTRFS_PATH" "MAPPING" "DEVICE" "${valueheaders}"

for path in "${paths[@]}"
do
	rawstats=$(btrfs device stats ${path})
	lastkey=""

	# loop through all stats output lines
	while IFS="" read -r p || [ -n "$p" ]
	do
	# capture the disk id (key) and value of each line
	# regex1: get stuff in [brackets], regex2: get the first 9 chars after last /
	if [ "${verbose}" == "0" ]; then
		key=$( echo $p | sed -E "s/\[(.*)\].*/\1/" | sed -E "s/.*\/([^/]*)/\1/" )
	else
		key=$( echo $p | sed -E "s/\[(.*)\].*/\1/" )
	fi
	# regex: get what's after the space (the number value)
	rawvalue=$(echo $p | sed -E "s/.* +//")
	
	if [ "${verbose}" == "0" ]; then
		device="$(printf "%s" "${lsblk}" | grep "${key}" | awk '{printf $1}' | sed -E "s/\/dev\///")"
	else
		device="$(printf "%s" "${lsblk}" | grep "${key}" | awk '{printf $1}')"
	fi

	# convert any non-zero values to "x" and zeroes to "."
	if [ "${verbose}" == "0" ]; then
		if [ "${rawvalue}" == "0" ]; then
			value='.'
		else
			value="x"
		fi
		valuesize=1
	else
		value=${rawvalue}
		valuesize=8
	fi

	# if the key changed, and it wasn't blank, put a newline
	if [ "${key}" != "${lastkey}" ] && [ "${lastkey}" != "" ]; then
		echo ""
	fi 

	# if the key changed, put key value, otherwise just value
	if [ "${key}" != "${lastkey}" ]; then
		printf "%-${longest_path}s  %-${mapping_length}.${mapping_length}s  %-${longest_device}s  %${valuesize}s" "${path}" "${key}" "${device}" "${value}" 
	else
		if [ "${verbose}" == "0" ]; then
			printf "%${valuesize}s" "${value}"
		else
			printf "  %${valuesize}s" "${value}"
		fi
	fi

	# record the key for next loop
	lastkey=$key

	done <<< ${rawstats}
	echo ""
done