$NetBSD: patch-hotplug_NetBSD_block,v 1.3 2016/05/21 20:12:18 bad Exp $

Use a lock around the allocation of an unused vnd because xl(1) starts
the hotplug scripts in parallel.

Use "stat -L" to get device major/minor numbers through symlinks e.g. for
lvm volumes.

--- hotplug/NetBSD/block.orig	2014-09-02 08:22:57.000000000 +0200
+++ hotplug/NetBSD/block	2016-05-21 17:03:35.000000000 +0200
@@ -6,6 +6,7 @@
 
 DIR=$(dirname "$0")
 . "${DIR}/hotplugpath.sh"
+. "${DIR}/locking.sh"
 
 PATH=${BINDIR}:${SBINDIR}:${LIBEXEC}:${PRIVATE_BINDIR}:/bin:/usr/bin:/sbin:/usr/sbin
 export PATH
@@ -62,6 +63,7 @@
 			available_disks="$available_disks $disk"
 			eval $disk=free
 		done
+		claim_lock block
 		# Mark the used vnd(4) devices as ``used''.
 		for disk in `sysctl hw.disknames`; do
 			case $disk in
@@ -77,6 +79,7 @@
 				break	
 			fi
 		done
+		release_lock block
 		if [ x$device = x ] ; then
 			error "no available vnd device"
 		fi
@@ -86,7 +89,7 @@
 		device=$xparams
 		;;
 	esac
-	physical_device=$(stat -f '%r' "$device")
+	physical_device=$(stat -L -f '%r' "$device")
 	xenstore-write $xpath/physical-device $physical_device
 	xenstore-write $xpath/hotplug-status connected
 	exit 0