Re: [PATCH] fstests: btrfs/150 regression test for reading compressed data

[Liu Bo <bo.li.liu@oracle.com>]

On Thu, Sep 21, 2017 at 03:03:45PM +0800, Lu Fengqi wrote:
> On Wed, Sep 20, 2017 at 05:52:43PM -0600, Liu Bo wrote:
> >We had a bug in btrfs compression code which could end up with a
> >kernel panic.
> >
> >This is adding a regression test for the bug and I've also sent a
> >kernel patch to fix the bug.
> >
> >The patch is "Btrfs: fix kernel oops while reading compressed data".
> >
> >Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
> >---
> > tests/btrfs/150     | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> > tests/btrfs/150.out |   3 ++
> > tests/btrfs/group   |   1 +
> > 3 files changed, 106 insertions(+)
> > create mode 100755 tests/btrfs/150
> > create mode 100644 tests/btrfs/150.out
> >
> >diff --git a/tests/btrfs/150 b/tests/btrfs/150
> >new file mode 100755
> >index 0000000..834be51
> >--- /dev/null
> >+++ b/tests/btrfs/150
> >@@ -0,0 +1,102 @@
> >+#! /bin/bash
> >+# FS QA Test btrfs/150
> >+#
> >+# This is a regression test which ends up with a kernel oops in btrfs.
> >+# It occurs when btrfs's read repair happens while reading a compressed
> >+# extent.
> >+# The patch for this is 
> >+# xxxxx
> >+#
> >+#-----------------------------------------------------------------------
> >+# Copyright (c) 2017 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.*
> >+}
> >+
> >+# 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_fail_make_request
> >+_require_scratch_dev_pool 2 
> >+
> >+SYSFS_BDEV=`_sysfs_dev $SCRATCH_DEV`
> >+enable_io_failure()
> >+{
> >+        echo 100 > $DEBUGFS_MNT/fail_make_request/probability
> >+        echo 1000 > $DEBUGFS_MNT/fail_make_request/times
> 
> What does 1000 mean? Enough failures?
> Why not set times to -1?

This was copied from another test, so I kept it as is.

As this test just submits a single 8K read after enabling fault
injection, 1000 is in fact as same as -1(no limit), I think 1000 is OK
to use.

thanks,
-liubo

> 
> >+        echo 0 > $DEBUGFS_MNT/fail_make_request/verbose
> >+        echo 1 > $SYSFS_BDEV/make-it-fail
> >+}
> >+
> >+disable_io_failure()
> >+{
> >+        echo 0 > $SYSFS_BDEV/make-it-fail
> >+        echo 0 > $DEBUGFS_MNT/fail_make_request/probability
> >+        echo 0 > $DEBUGFS_MNT/fail_make_request/times
> >+}
> >+
> >+_scratch_pool_mkfs "-d raid1 -b 1G" >> $seqres.full 2>&1
> >+
> >+# It doesn't matter which compression algorithm we use.
> >+_scratch_mount -ocompress
> >+
> >+# Create a file with all data being compressed
> >+$XFS_IO_PROG -f -c "pwrite -W 0 8K" $SCRATCH_MNT/foobar | _filter_xfs_io
> >+
> >+# Raid1 consists of two copies and btrfs decides which copy to read by reader's
> >+# %pid.  Now we inject errors to copy #1 and copy #0 is good.  We want to read
> >+# the bad copy to trigger read-repair.
> >+while true; do
> >+	disable_io_failure
> >+	# invalidate the page cache
> >+	$XFS_IO_PROG -f -c "fadvise -d 0 128K" $SCRATCH_MNT/foobar | _filter_xfs_io
> >+
> >+	enable_io_failure
> >+	od -x $SCRATCH_MNT/foobar > /dev/null &
> >+	pid=$!
> >+	wait
> >+	[ $((pid % 2)) == 1 ] && break
> >+done
> >+
> >+disable_io_failure
> >+
> >+# success, all done
> >+status=0
> >+exit
> >diff --git a/tests/btrfs/150.out b/tests/btrfs/150.out
> >new file mode 100644
> >index 0000000..c492c24
> >--- /dev/null
> >+++ b/tests/btrfs/150.out
> >@@ -0,0 +1,3 @@
> >+QA output created by 150
> >+wrote 8192/8192 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 70c3f05..b70a122 100644
> >--- a/tests/btrfs/group
> >+++ b/tests/btrfs/group
> >@@ -152,3 +152,4 @@
> > 147 auto quick send
> > 148 auto quick rw
> > 149 auto quick send compress
> >+150 auto quick
> >-- 
> >2.5.0
> >
> >--
> >To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> >the body of a message to majordomo@vger.kernel.org
> >More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> >
> 
> -- 
> Thanks,
> Lu
> 
>