added helper script for block device mounting

diff --git a/fusedisk b/fusedisk
new file mode 100755 (executable)
index 0000000..f7df50e
--- /dev/null
+++ b/fusedisk
@@ -0,0 +1,42 @@
+#!/bin/sh
+#
+# Set up a fusefile as a disk device using device mapper.
+# Note that this requires root access.
+
+if [ $(id -u) != 0 ] ; then
+    echo "block device set up requires root." >&2
+    exit 1
+fi
+
+# fuse blkdev mounting needs to sniff an existing but unmounted block
+# device node for setup. However the device mapping has an empty table
+# and the content is only accessible via the fuse mount that links it
+# to the fusefile process. The device node (major:minor) are still
+# considered in use by the kernel and, and the device node is "open"
+# while mounted.
+
+[ -e /dev/mapper/control ] || modprobe dm_mod || exit 1
+
+# Create up to N fusedisk named as fusedisk0..fusediskN, the device
+# mapper also creates its dm-X device nodes and we also force
+# /dev/mapper/$NAME nodes for them.
+N=15
+DEV=
+for I in $(seq 0 $N) ; do
+    NAME=fusedisk$I
+    C="$(dmsetup info --noheadings -c -o open $NAME 2>/dev/null)"
+    if [ "$C" != "1" ] ; then
+       if [ -z "$C" ] ; then
+            dmsetup create $NAME --notable || exit 1
+           dmsetup mknodes $NAME || exit 1
+       fi
+       DEV=/dev/mapper/$NAME
+       break
+    fi
+done
+if [ -z "$DEV" ] ; then
+    echo "** No more fusedisk devices" >&2
+    exit 1
+fi
+echo "using $DEV for $*" | logger -t fusedisk
+exec fusefile -oblkdev,fsname=$DEV -oallow_other $*