#! /bin/sh
#
#       try-xfs-prealloc
#
# This script will create a file on an XFS file system and let it grow
# (in increments of 10 * 16 kB) continuously, without closing it.
#
# In parallel, "ls -l" and "du" will be used to check the file size
# and disk allocation.


# Settings
TESTDISK=/XFS_try
TESTFILE=${TESTDISK}/somedir/bigfile
FILLBYTES=/Downloads/ISO/SLE-12-Server-DVD-x86_64-GM-DVD2.iso # Any big file will do

# The terminal is ...
TTY=`ps -fp $$ | sed -n 's=.* \(pts/[0-9]*\) .*=\1=p'`
echo
echo "Test '$0' is running on TTY '$TTY'."

# Ensure initial status
mkdir -p `dirname $TESTFILE`
rm -f $TESTFILE

# Log the test settings
echo
uname -a
mount | fgrep $TESTDISK
df $TESTDISK

# Set up a pipe for the data, ensure it will not be closed too early.
DATAPIPE=/tmp/xfs-tst-$$
mkfifo $DATAPIPE
cat </dev/tty >$DATAPIPE &  # Will run until killed.
PID_CAT=$!

# Cleanup function
cleanup ()
{
    kill -9 $PID_CAT
    rm -f $DATAPIPE
}

# Establish cleanup function
trap cleanup 0

# The test file must not be closed, but should grow in clear increments.
# Use "dd" for the increments.
# Feed it in pieces via a named pipe to limit the speed.

# The process to extend the test file.
# Run forever. Will die when its input pipe is closed and removed.
dd if=$DATAPIPE of=$TESTFILE obs=16k >/dev/null 2>&1 &

# A loop to get the data to write, but in discrete portions.
CNT=0
while [ $CNT -lt 17500 ]
do
    CNT=`expr $CNT + 1`
    dd if=$FILLBYTES bs=16k count=10 skip=$CNT of=$DATAPIPE >/dev/null 2>&1
    echo -n .
    if [ `expr $CNT % 100` -eq 0 ]; then
	echo
        ls -ld --block-size=K $TESTFILE
	du -k  $TESTFILE
    fi
    if [ `expr $CNT % 5` -eq 0 ]; then
        sleep 1
    fi
done

# The end ...
echo
echo =====
echo "No further writes, file still open, status:"
ls -ld --block-size=K $TESTFILE ; du -k  $TESTFILE

cleanup >/dev/null 2>&1
trap '' 0

echo
echo "Writer process finished, status:"
ls -ld --block-size=K $TESTFILE ; du -k  $TESTFILE