new file mode 100755
@@ -0,0 +1,94 @@
+#! /bin/bash
+# FS QA Test 027
+#
+# When btrfs is using cow mode, buffered writes of sub-pagesize can end up with
+# single 4k extents.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2016 Liu Bo. 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.*
+
+ # restore expire
+ echo $default_expire > /proc/sys/vm/dirty_expire_centisecs
+}
+
+# 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 btrfs
+_supported_os Linux
+_require_scratch
+_require_xfs_io_command "fiemap"
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+
+default_expire=`cat /proc/sys/vm/dirty_expire_centisecs`
+echo 50 > /proc/sys/vm/dirty_expire_centisecs
+tfile=$SCRATCH_MNT/testfile
+
+PAGE_SIZE=$(get_page_size)
+SUBLEN=$((RANDOM % PAGE_SIZE))
+
+$XFS_IO_PROG -f -c "pwrite 0 $PAGE_SIZE" $tfile > /dev/null 2>&1
+$XFS_IO_PROG -c "pwrite $PAGE_SIZE $SUBLEN" $tfile > /dev/null 2>&1
+
+toff=$((PAGE_SIZE + SUBLEN))
+for ((i=0; i<10000; i++))
+do
+ tlen=$PAGE_SIZE
+ if [ $((i % 2)) = 0 ]; then
+ tlen=$((PAGE_SIZE * 3))
+ fi
+ if [ $((i % 1000)) = 0 ]; then
+ tlen=$((RANDOM % PAGE_SIZE))
+ fi
+
+ $XFS_IO_PROG -c "pwrite $toff $tlen" $tfile > /dev/null 2>&1
+ toff=$((toff + tlen))
+done
+
+sync
+
+# check for single PAGESIZE extent
+$XFS_IO_PROG -c "fiemap -v" $tfile >> $seqres.full 2>&1
+$XFS_IO_PROG -c "fiemap -v" $tfile | awk '{if ($4 == 8) print $4}'
+
+# success, all done
+status=0
+exit
new file mode 100644
@@ -0,0 +1,2 @@
+QA output created by 027
+8
@@ -29,6 +29,7 @@
024 auto quick compress
025 auto quick send clone
026 auto quick compress prealloc
+027 auto
029 auto quick clone
030 auto quick send
031 auto quick subvol clone
This is to test if COW enabled btrfs can end up with single 4k extents when doing subpagesize buffered writes. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> --- tests/btrfs/027 | 94 +++++++++++++++++++++++++++++++++++++++++++++++++++++ tests/btrfs/027.out | 2 ++ tests/btrfs/group | 1 + 3 files changed, 97 insertions(+) create mode 100755 tests/btrfs/027 create mode 100644 tests/btrfs/027.out