generic: Add test for fallocate() PUNCH_HOLE|KEEP_SIZE

Verify that punching holes at ends of files does not alter st_size
if we pass FALLOC_FL_KEEP_SIZE to fallocate().

[eguan: add comment about xfs_io's fpunch KEEP_SIZE flag]

Signed-off-by: Calvin Owens <calvinowens@fb.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

tests/generic/420

@@ -0,0 +1,65 @@
+#! /bin/bash
+# FS QA Test 420
+#
+# Verify fallocate(mode=FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE) does
+# not alter the file size.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2017 Calvin Owens.  All Rights Reserved.
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License as
+# published by the Free Software Foundation.
+#
+# This program is distributed in the hope that it would be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write the Free Software Foundation,
+# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+#-----------------------------------------------------------------------
+#
+
+seq=`basename $0`
+seqres=$RESULT_DIR/$seq
+echo "QA output created by $seq"
+
+here=`pwd`
+tmp=/tmp/$$
+status=1	# failure is the default!
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+_cleanup()
+{
+	cd /
+	rm -f $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# remove previous $seqres.full before test
+rm -f $seqres.full
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs generic
+_supported_os Linux
+_require_test
+_require_xfs_io_command fpunch
+
+testfile="${TEST_DIR}/testfile"
+
+echo "Testing fallocate(mode=FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)"
+$XFS_IO_PROG -fc "pwrite -b 2048 0 2048" $testfile | head -n1
+# fpunch from xfs_io has KEEP_SIZE flag set
+$XFS_IO_PROG -c "fpunch 2048 2048" $testfile
+$XFS_IO_PROG -c "stat" $testfile | grep -F 'stat.size'
+
+# success, all done
+status=0
+exit

tests/generic/420.out

@@ -0,0 +1,4 @@
+QA output created by 420
+Testing fallocate(mode=FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE)
+wrote 2048/2048 bytes at offset 0
+stat.size = 2048

tests/generic/group

@@ -422,3 +422,4 @@
 417 auto quick shutdown log
 418 auto rw
 419 auto quick encrypt
+420 auto quick punch