btrfs: add regression for inode bad compression ratio detection

This test add a regression test to make sure btrfs dosen't set
inode NOCOMPRESS flag when a small write(<=blocksize) happens.

Signed-off-by: Wang Shilong <wangshilong1991@gmail.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

tests/btrfs/076

@@ -0,0 +1,74 @@
+#! /bin/bash
+# FS QA Test No. btrfs/076
+#
+# Regression test for btrfs incorrect inode ratio detection.
+# This was fixed in the following linux kernel patch:
+#
+#     Btrfs: fix incorrect compression ratio detection
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2014 Wang Shilong.  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 -fr $tmp
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+. ./common/defrag
+
+# real QA test starts here
+_supported_fs btrfs
+_supported_os Linux
+_require_test
+_require_scratch
+_need_to_be_root
+
+rm -f $seqres.full
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount "-o compress=lzo"
+
+$XFS_IO_PROG -f -c "pwrite 0 10M" -c "fsync" \
+	$SCRATCH_MNT/data >> $seqres.full 2>&1
+
+_extent_count $SCRATCH_MNT/data
+
+$XFS_IO_PROG -f -c "pwrite 0 $((4096*33))" -c "fsync" \
+	$SCRATCH_MNT/data >> $seqres.full 2>&1
+
+$XFS_IO_PROG -f -c "pwrite 0 10M" -c "fsync" \
+	$SCRATCH_MNT/data >> $seqres.full 2>&1
+
+_extent_count $SCRATCH_MNT/data
+
+status=0
+exit

tests/btrfs/076.out

@@ -0,0 +1,3 @@
+QA output created by 076
+80
+80

tests/btrfs/group

@@ -78,3 +78,4 @@
 073 auto scrub remount compress
 074 auto defrag remount compress
 075 auto quick subvol
+076 auto quick