diff mbox

fstests: btrfs: Add reserved space leak check for rewrite dirty page

Message ID 1439790068-24470-1-git-send-email-quwenruo@cn.fujitsu.com (mailing list archive)
State New, archived
Headers show

Commit Message

Qu Wenruo Aug. 17, 2015, 5:41 a.m. UTC
Btrfs qgroup reserve codes lacks check for rewrite dirty page, causing
every write, even rewriting a uncommitted dirty page, to reserve space.

But only written data will free the reserved space, causing reserved
space leaking.

The bug exists almost from the beginning of btrfs qgroup codes, but
nobody found it.

For example:

1)Write [0, 12K) into file A
  reserve 12K space

File A:
0	4K	8K	12K
|<--------dirty-------->|
reserved: 12K

2)Write [0,4K) into file A
0	4K	8K	12K
|<--------dirty-------->|
reserved: 16K <<< Should be 12K
As the dirty pages are not committed yet, we don't need to reserve extra space.

3) Commit transaction
Dirty pages [0,12) written to disk.
Free 12K reserved space.
reserved: 4K <<< Should be 0

This testcase will test such problem.
Kernel fix will need some huge change, so won't be soon.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
---
 tests/btrfs/089     | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/btrfs/089.out | 13 +++++++++
 tests/btrfs/group   |  1 +
 3 files changed, 96 insertions(+)
 create mode 100755 tests/btrfs/089
 create mode 100644 tests/btrfs/089.out
diff mbox

Patch

diff --git a/tests/btrfs/089 b/tests/btrfs/089
new file mode 100755
index 0000000..76d733e
--- /dev/null
+++ b/tests/btrfs/089
@@ -0,0 +1,82 @@ 
+#! /bin/bash
+# FS QA Test 089
+#
+# Check for btrfs reserved space leaking caused by overlap dirty range.
+# This problem exists almost from qgroup function.
+#
+#-----------------------------------------------------------------------
+# Copyright (c) 2015 Fujitsu. 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 $tmp.*
+}
+
+# get standard environment, filters and checks
+. ./common/rc
+. ./common/filter
+
+# real QA test starts here
+
+# Modify as appropriate.
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+_need_to_be_root
+
+# Use big blocksize to ensure there is still enough space left for metadata
+# space reserve.
+BLOCKSIZE=$(( 2 * 1024 * 1024 )) # 2M block size
+FILESIZE=$(( 128 * 1024 * 1024 )) # 128M file size
+
+_scratch_mkfs >> $seqres.full 2>&1
+_scratch_mount
+_require_fs_space $SCRATCH_MNT $(($FILESIZE * 2 / 1024))
+
+_run_btrfs_util_prog quota enable $SCRATCH_MNT
+_run_btrfs_util_prog qgroup limit $FILESIZE 5 $SCRATCH_MNT
+
+# loop 5 times without sync to ensure reserved space leak will happen
+for i in `seq 1 5`; do
+	$XFS_IO_PROG -f -c "pwrite -b $BLOCKSIZE 0 $(($FILESIZE / 2))" \
+		$SCRATCH_MNT/foo | _filter_xfs_io
+done
+
+# remove the file and sync, to ensure all space freed
+sync
+# shouldn't happen, as BLOCKSIZE is large enough for metdata cow
+rm $SCRATCH_MNT/foo || _fail "reserved space leak detected"
+sync
+
+# We should be able to write $FILESIZE - $BLOCKSIZE data
+$XFS_IO_PROG -f -c "pwrite -b $BLOCKSIZE 0 $(($FILESIZE - $BLOCKSIZE))" \
+	$SCRATCH_MNT/foo | _filter_xfs_io
+
+# success, all done
+status=0
+exit
diff --git a/tests/btrfs/089.out b/tests/btrfs/089.out
new file mode 100644
index 0000000..2690191
--- /dev/null
+++ b/tests/btrfs/089.out
@@ -0,0 +1,13 @@ 
+QA output created by 089
+wrote 67108864/67108864 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 67108864/67108864 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 67108864/67108864 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 67108864/67108864 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 67108864/67108864 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 132120576/132120576 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
diff --git a/tests/btrfs/group b/tests/btrfs/group
index ffe18bf..da37e46 100644
--- a/tests/btrfs/group
+++ b/tests/btrfs/group
@@ -91,6 +91,7 @@ 
 086 auto quick clone
 087 auto quick send
 088 auto quick metadata
+089 auto qgroup
 090 auto quick metadata
 091 auto quick qgroup
 092 auto quick send