reflink: more tests

Add more tests for unaligned copy-on-write things, and explicitly
test the ability to pass "len == 0" to mean reflink/dedupe all
the way to the end of the file".

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/generic/178

@@ -0,0 +1,77 @@
+#! /bin/bash
+# FS QA Test No. 178
+#
+# Ensure that punch-hole doesn't clobber CoW.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015, Oracle and/or its affiliates.  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 -rf "$tmp".* "$TESTDIR"
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/reflink
+
+# real QA test starts here
+_supported_os Linux
+_require_test_reflink
+_require_cp_reflink
+_require_xfs_io_command "fpunch"
+
+rm -f "$seqres.full"
+
+TESTDIR="$TEST_DIR/test-$seq"
+rm -rf "$TESTDIR"
+mkdir "$TESTDIR"
+
+echo "Create the original files"
+BLKSZ=65536
+NR=512
+_pwrite_byte 0x61 0 $((BLKSZ * NR)) "$TESTDIR/file1" >> "$seqres.full"
+
+_cp_reflink "$TESTDIR/file1" "$TESTDIR/file2"
+_test_remount
+
+md5sum "$TESTDIR/file1" | _filter_test_dir
+md5sum "$TESTDIR/file2" | _filter_test_dir
+
+echo "Write and punch"
+_pwrite_byte 0x62 0 $((BLKSZ * 256)) "$TESTDIR/file2" >> "$seqres.full"
+"$XFS_IO_PROG" -f -c "fpunch $BLKSZ $((BLKSZ * 254))" "$TESTDIR/file2"
+_test_remount
+
+echo "Compare results"
+md5sum "$TESTDIR/file1" | _filter_test_dir
+md5sum "$TESTDIR/file2" | _filter_test_dir
+
+# success, all done
+status=0
+exit