create_job_tmdir: Add helper script

Add helpder script to set up and mount a tmpdir volume for a job. Use
ext4, because is causes less load on the system than xfs. Tune
filesystem for speed, not for durability.

Makefile

@@ -596,6 +596,11 @@ build: mxqps
 
 clean: CLEAN += mxqps
 
+### script helper -----------------------------------------------------
+
+install:: helper/create_job_tmpdir
+	$(call quiet-install,0755,$^,${DESTDIR}${LIBEXECDIR}/mxq/create_job_tmpdir)
+
 ########################################################################
 
 fix: FIX += mxqdctl-hostconfig.sh

helper/create_job_tmpdir

@@ -0,0 +1,40 @@
+#! /usr/bin/bash
+
+# Input (environment):
+#
+#   MXQ_JOBID   : job ident
+#   MXQ_SIZE    : size in GB
+#   MXQ_UID     : uid
+
+# Output:
+#
+#   /dev/shm/mxqd/tmp/$JOBID  mounted, space from /scratch/local2
+
+tmpdir=/scratch/local2/mxqd/tmp
+mntdir=/dev/shm/mxqd/mnt/job
+filename=$tmpdir/$MXQ_JOBID.tmp
+mountpoint=$mntdir/$MXQ_JOBID
+
+umask 006
+mkdir -p $tmpdir
+mkdir -p $mntdir
+
+status=1;
+
+if fallocate -l ${MXQ_SIZE}G $filename; then
+    if loopdevice=$(losetup --find --show $filename); then
+        if mkfs.ext4 \
+                -m 0 \
+                -E nodiscard,mmp_update_interval=300,lazy_journal_init=1,root_owner=$MXQ_UID:0 \
+                -O '64bit,ext_attr,filetype,^has_journal,huge_file,inline_data,^mmp,^quota,sparse_super2' \
+                $loopdevice \
+                && mkdir -p $mountpoint && mount -Odata=writeback,barrier=0  $loopdevice $mountpoint; then
+            status=0
+        fi
+        losetup -d $loopdevice
+    fi
+    rm $filename
+else
+    test -e $fileame && rm $filename
+fi
+exit $status