diff --git a/nagios/check_btrfs_quota.sh b/nagios/check_btrfs_quota.sh
new file mode 100755
index 0000000..e4ede15
--- /dev/null
+++ b/nagios/check_btrfs_quota.sh
@@ -0,0 +1,244 @@
+#!/bin/sh
+
+# Little check for quota usage on Btrfs subvolumes
+# GPL v3+ (copyright chl-dev@bugness.org)
+
+PROGPATH=$( echo $0 | sed -e 's,[\\/][^\\/][^\\/]*$,,' )
+REVISION="0.1"
+
+# Stop at the first non-catched error
+set -e
+
+# Include check_range()
+# Not needed at the moment
+#. $PROGPATH/utils.sh
+STATE_OK=0
+STATE_WARNING=1
+STATE_CRITICAL=2
+STATE_UNKNOWN=3
+STATE_DEPENDENT=4
+
+# Default values
+RANGE_WARNING="20%"
+RANGE_CRITICAL="10%"
+
+# Output
+OUTPUT_EXIT_STATUS=$STATE_OK
+OUTPUT_DETAIL_OK=""
+OUTPUT_DETAIL_WARNING=""
+OUTPUT_DETAIL_CRITICAL=""
+OUTPUT_PERFDATA=""
+
+#
+# Help function
+#
+usage() {
+	cat <<EOF
+Usage :
+  $0 [-w warning-free-space%] [-c critical-free-space%] -V volume -V...
+
+Example :
+  ./check_btrfs_quota -w 20% -c 10% -V /home
+
+We adopt the same behaviour than check_disks so thresholds are matched
+against "free" space. The example above will trigger a warning if less
+than 20% of maxrfer or maxecl is available.
+
+Note: Since the volumes are checked against the latest thresholds specified, order
+      of the arguments is important. Ex:
+      ./check_btrfs_quota -w 20% -V /home -w 50% -V /tmp
+
+Default values:
+	warning-free-space:	$RANGE_WARNING
+	critical-free-space:	$RANGE_CRITICAL
+EOF
+}
+
+check_range_syntax() {
+	return 0
+}
+#	check_range 0 "$1" >/dev/null 2>&1
+#	if [ "$?" -eq "2" ]; then
+#		return 1
+#	fi
+#	return 0
+#}
+
+#
+# Remove the '%' suffix (or error if no '%')
+#
+get_percent() {
+	if [ "$( echo -n "$1" | tail -c 1 )" = "%" ]; then
+		echo -n "$1" | head -c -1
+		return 0
+	fi
+	return 1
+}
+
+#
+# Returns 0 if freespace is above threshold, 1 if not
+#
+# args:
+# - "free" space value
+# - quota (aka. maximum space possible)
+# - threshold (in percent with a '%' suffix, or plain unit)
+#
+check_freespace_is_above_threshold() {
+	local VALUE="$1"
+	local MAXVALUE="$2"
+	local THRESHOLD="$3"
+
+	if get_percent "$THRESHOLD" >/dev/null; then
+		VALUE="$(( $VALUE * 100 / $MAXVALUE ))"
+		THRESHOLD="$( get_percent "$THRESHOLD" )"
+	fi
+
+	if [ "$VALUE" -le "$THRESHOLD" ]; then
+		return 1
+	fi
+	return 0
+}
+
+#
+# Factorize output in the form of:
+#  /home:0/260 (refr:10M(50%) excl:5M(20%)
+# args:
+# 1: VOLUME
+# 2: QGROUPID
+# 3: REFR
+# 4: EXCL
+# 5: MAXRFER
+# 6: MAXEXCL
+format_output_item() {
+	local LOCAL_OUTPUT=""
+	if [ "$5" != "none" ]; then
+		LOCAL_OUTPUT="$( printf "rfer:%s(%d%%)" \
+			"$( numfmt --to=iec $(( $5 - $3 )) )" \
+			"$(( 100 * ($5 - $3) / $5 ))" \
+			)"
+	fi
+	if [ "$6" != "none" ]; then
+		[ -n "$LOCAL_OUTPUT" ] && LOCAL_OUTPUT="$LOCAL_OUTPUT "
+		LOCAL_OUTPUT="$( printf "excl:%s(%d%%)" \
+			"$( numfmt --to=iec $(( $6 - $4 )) )" \
+			"$(( 100 * ($6 - $4) / $6 ))" \
+			)"
+	fi
+	if [ -n "$LOCAL_OUTPUT" ]; then
+		printf "%s:%s (%s)" "$1" "$2" "$LOCAL_OUTPUT"
+	fi
+}
+
+# Some early checks
+if ! which btrfs 2>&1 >/dev/null; then
+	echo "UNKNOWN 'btrfs' command not found."
+	exit $STATE_UNKNOWN
+fi
+
+#
+# Loop on parameters + tests
+#
+while getopts hw:c:V: f; do
+	case "$f" in
+		'h')
+			usage
+			exit
+			;;
+
+		'w')
+			if check_range_syntax "$OPTARG" >/dev/null; then
+				RANGE_WARNING="$OPTARG"
+			else
+				echo "UNKNOWN: invalid range."
+				exit 3
+			fi
+			;;
+
+		'c')
+			if check_range_syntax "$OPTARG" >/dev/null; then
+				RANGE_CRITICAL="$OPTARG"
+			else
+				echo "UNKNOWN: invalid range."
+				exit 3
+			fi
+			;;
+
+		'V')
+			VOLUME="$OPTARG"
+
+			# Quickly check if we have enough permission to launch btrfs commands
+			if ! btrfs qgroup show "$VOLUME" >/dev/null 2>&1 ; then
+				echo "UNKNOWN: unable to launch 'btrfs qgroup show $VOLUME' command."
+				exit $STATE_UNKNOWN
+			fi
+
+			# Loop on each qgroup
+			# (the kinda weird <<EOF at the end is to avoid entering a sub-shell, so we can keep
+			# our precious vars even with prosix-strict dash)
+			while read QGROUPID RFER EXCL MAXRFER MAXEXCL; do
+				LOOP_OUTPUT_STATUS=$STATE_OK
+				if [ "$MAXRFER" != "none" ]; then
+					FREERFER="$(( $MAXRFER - $RFER ))"
+					if ! check_freespace_is_above_threshold "$FREERFER" "$MAXRFER" "$RANGE_CRITICAL"; then
+						OUTPUT_EXIT_STATUS=$STATE_CRITICAL
+						LOOP_OUTPUT_STATUS=$STATE_CRITICAL
+					elif ! check_freespace_is_above_threshold "$FREERFER" "$MAXRFER" "$RANGE_WARNING"; then
+						[ "$OUTPUT_EXIT_STATUS" = "$STATE_OK" ] && OUTPUT_EXIT_STATUS=$STATE_WARNING
+						LOOP_OUTPUT_STATUS=$STATE_WARNING
+					fi
+				fi
+				if [ "$MAXEXCL" != "none" ]; then
+					FREEEXCL="$(( $MAXEXCL - $EXCL ))"
+					if ! check_freespace_is_above_threshold "$FREEEXCL" "$MAXEXCL" "$RANGE_CRITICAL"; then
+						OUTPUT_EXIT_STATUS=$STATE_CRITICAL
+						LOOP_OUTPUT_STATUS=$STATE_CRITICAL
+					elif ! check_freespace_is_above_threshold "$FREEEXCL" "$MAXEXCL" "$RANGE_WARNING"; then
+						[ "$OUTPUT_EXIT_STATUS" = "$STATE_OK" ] && OUTPUT_EXIT_STATUS=$STATE_WARNING
+						[ "$LOOP_OUTPUT_STATUS" = "$STATE_OK" ] && LOOP_OUTPUT_STATUS=$STATE_WARNING
+					fi
+				fi
+
+				# Depending on the alerts raised during this loop, we store
+				# the output in ok/warning/critical. This way, in case of critical
+				# alert, we don't list all the ok data.
+				TMP="$( format_output_item "$VOLUME" "$QGROUPID" "$RFER" "$EXCL" "$MAXRFER" "$MAXEXCL" )"
+				case "$LOOP_OUTPUT_STATUS" in
+					"$STATE_OK")
+						OUTPUT_DETAIL_OK="$OUTPUT_DETAIL_OK $TMP" ;;
+					"$STATE_WARNING")
+						OUTPUT_DETAIL_WARNING="$OUTPUT_DETAIL_WARNING $TMP" ;;
+					"$STATE_CRITICAL")
+						OUTPUT_DETAIL_CRITICAL="$OUTPUT_DETAIL_CRITICAL $TMP" ;;
+				esac
+
+				OUTPUT_PERFDATA="$( printf "%s\n%s\n%s" "$OUTPUT_PERFDATA" "$VOLUME:$QGROUPID:rfer=$RFER" "$VOLUME:$QGROUPID:excl=$EXCL" )"
+			done <<EOF
+$( btrfs qgroup show -re --raw "$VOLUME" | tail -n +3 )
+EOF
+			;;
+
+		\?)
+			usage
+			exit 1
+			;;
+	esac
+done
+
+case "$OUTPUT_EXIT_STATUS" in
+	'0')
+		printf "OK %s" "$OUTPUT_DETAIL_OK"
+		;;
+	'1')
+		printf "WARNING %s" "$OUTPUT_DETAIL_WARNING"
+		;;
+	'2')
+		printf "CRITICAL %s" "$OUTPUT_DETAIL_CRITICAL"
+		;;
+	*)
+		printf "UNKNOWN"
+		;;
+esac
+
+# We sort the perfdata because of a weird bug in some icinga/pnp4nagios interactions
+printf "|%s\n" "$( printf "%s" "$OUTPUT_PERFDATA" | sort | grep -v "^$" | tr "\n" " " )"
+exit $OUTPUT_EXIT_STATUS