# No mdadm? No mdraid support.
which mdadm >/dev/null 2>&1 || exit 1
-# We were asked to run in hostonly mode, so pass the check only if there
-# is an mdraid volume in use somewhere. This should really check to see if
-# root is on an mdraid volume only, but I am lazy.
-if [[ $1 = -h ]]; then
- blkid | grep -q linux_raid || exit 1
+is_mdraid() { /lib/udev/vol_id /dev/block/$1 |egrep -q '(linux|isw)_raid'; }
+
+check_block_and_slaves() (
+ # $1 = block device in major:minor format
+ local x
+ cd /sys/dev/block/$1
+ [[ -b /dev/block/$1 ]] || return 1 # Not a block device? So sorry.
+ is_mdraid $1 && return
+ [[ -d slaves ]] || return 1 # there are no underlying devices, done.
+ # we want to search the tree breadthwise, so...
+ for x in slaves/*/dev; do
+ is_mdraid $(cat "$x") && return 0
+ done
+ for x in slaves/*/dev; do
+ check_block_and_slaves $(cat "$x") && return 0
+ done
+ return 1
+)
+
+if [[ $1 = '-h' ]] ; then
+ rootdev=''
+ while read blkdev fs type opts misc; do
+ [[ $blkdev = rootfs ]] && continue # skip rootfs entry
+ [[ $fs = / ]] && { rootdev=$blkdev; break; }
+ done < /proc/mounts
+ [[ -b $rootdev ]] || exit 1 # Not on a block device? Definitly not mdraid.
+ # get major/minor for the device
+ majmin=$(ls -nLl "$rootdev" | \
+ (read x x x x maj min x; maj=${maj//,/}; echo $maj:$min))
+ # now, walk backwards though our master/slave relationships looking
+ # for a mdraid device
+ check_block_and_slaves $majmin || exit 1
fi
exit 0