[PATCH] fstests: btrfs, verify fitrim does not discard reserved device area

fdmanana
2016-01-08T11:04:52Z

From: Filipe Manana <fdmanana@suse.com>

Verify that when a fitrim operation is made against a btrfs filesystem,
the ranges [0, 64Kb[ and [68Kb, 1Mb[ of the device are not discarded,
they remain with the content they had before the fitrim operation. These
regions of the device are reserved for a boot loader to use at its will.

In the 4.3 linux kernel we got a regression that allowed a fitrim
operation to discard these reserved ranges of the device, resulting in
the filesystem becoming unbootable after a fitrim. The issue is fixed
by the following patch (targeted for 4.5 and 4.3/4.4 stable releases):

"Btrfs: fix fitrim discarding device area reserved for boot loader's use"

Signed-off-by: Filipe Manana <fdmanana@suse.com>
---
tests/btrfs/116 | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++
tests/btrfs/116.out | 12 +++++++++
tests/btrfs/group | 1 +
3 files changed, 89 insertions(+)
create mode 100755 tests/btrfs/116
create mode 100644 tests/btrfs/116.out

diff --git a/tests/btrfs/116 b/tests/btrfs/116
new file mode 100755
index 0000000..c51e135
--- /dev/null
+++ b/tests/btrfs/116
@@ -0,0 +1,76 @@
+#! /bin/bash
+# FSQA Test No. 116
+#
+# Verify that when a fitrim operation is made against a btrfs filesystem, the
+# ranges [0, 64Kb[ and [68Kb, 1Mb[ of the device are not discarded, they remain
+# with the content they had before the fitrim operation. These regions of the
+# device are reserved for a boot loader to use at its will.
+#
+#-----------------------------------------------------------------------
+#
+# Copyright (C) 2016 SUSE Linux Products GmbH. All Rights Reserved.
+# Author: Filipe Manana <fdmanana@suse.com>
+#
+# 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"
+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
+_need_to_be_root
+_supported_fs btrfs
+_supported_os Linux
+_require_scratch
+
+rm -f $seqres.full
+
+_scratch_mkfs >>$seqres.full 2>&1
+
+# Write to the [0, 64Kb[ and [68Kb, 1Mb[ ranges of the device. These ranges are
+# reserved for a boot loader to use (GRUB for example) and btrfs should never
+# use them - neither for allocating metadata/data nor should trim/discard them.
+# The range [64Kb, 68Kb[ is used for the primary superblock of the filesystem.
+$XFS_IO_PROG -c "pwrite -S 0xfd 0 64K" $SCRATCH_DEV | _filter_xfs_io
+$XFS_IO_PROG -c "pwrite -S 0xfd 68K 956K" $SCRATCH_DEV | _filter_xfs_io
+
+# Now mount the filesystem and perform a fitrim against it.
+_scratch_mount
+_require_batched_discard $SCRATCH_MNT
+$FSTRIM_PROG $SCRATCH_MNT
+
+# Now unmount the filesystem and verify the content of the ranges was not
+# modified (no trim/discard happened on them).
+_scratch_unmount
+echo "Content of the ranges [0, 64Kb] and [68Kb, 1Mb[ after fitrim:"
+od -t x1 -N $((64 * 1024)) $SCRATCH_DEV
+od -t x1 -j $((68 * 1024)) -N $((956 * 1024)) $SCRATCH_DEV
+
+status=0
+exit
diff --git a/tests/btrfs/116.out b/tests/btrfs/116.out
new file mode 100644
index 0000000..9cec94d
--- /dev/null
+++ b/tests/btrfs/116.out
@@ -0,0 +1,12 @@
+QA output created by 116
+wrote 65536/65536 bytes at offset 0
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 978944/978944 bytes at offset 69632
+XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Content of the ranges [0, 64Kb] and [68Kb, 1Mb[ after fitrim:
+0000000 fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
+*
+0200000
+0210000 fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
+*
+4000000
diff --git a/tests/btrfs/group b/tests/btrfs/group
index 3a99289..de628be 100644
--- a/tests/btrfs/group
+++ b/tests/btrfs/group
@@ -116,3 +116,4 @@
113 auto quick compress clone
114 auto qgroup
115 auto qgroup
+116 auto quick metadata
--
2.1.3