Re: [PATCH 2/3] generic: test shutdowns of a nested filesystem

[Eryu Guan <guan@eryu.me>]

On Tue, Jul 27, 2021 at 05:10:30PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> generic/475, but we're running fsstress on a disk image inside the
> scratch filesystem
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
>  tests/generic/725     |  136 +++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/725.out |    2 +
>  2 files changed, 138 insertions(+)
>  create mode 100755 tests/generic/725
>  create mode 100644 tests/generic/725.out
> 
> 
> diff --git a/tests/generic/725 b/tests/generic/725
> new file mode 100755
> index 00000000..f43bcb37
> --- /dev/null
> +++ b/tests/generic/725
> @@ -0,0 +1,136 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2021 Oracle, Inc.  All Rights Reserved.
> +#
> +# FS QA Test No. 725
> +#
> +# Test nested log recovery with repeated (simulated) disk failures.  We kick
> +# off fsstress on a loopback filesystem mounted on the scratch fs, then switch
> +# out the underlying scratch device with dm-error to see what happens when the
> +# disk goes down.  Having taken down both fses in this manner, remount them and
> +# repeat.  This test simulates VM hosts crashing to try to shake out CoW bugs
> +# in writeback on the host that cause VM guests to fail to recover.

It currently fails for me on btrfs, the loop mount failed in 2nd
iteration, seems like a bug in btrfs.

> +#
> +. ./common/preamble
> +_begin_fstest shutdown auto log metadata eio
> +
> +_cleanup()
> +{
> +	cd /
> +	$KILLALL_PROG -9 fsstress > /dev/null 2>&1
> +	wait
> +	if [ -n "$loopmnt" ]; then
> +		umount $loopmnt 2>/dev/null

$UMOUNT_PROG

> +		rm -r -f $loopmnt
> +	fi
> +	rm -f $tmp.*
> +	_dmerror_unmount
> +	_dmerror_cleanup
> +}
> +
> +# Import common functions.
> +. ./common/dmerror
> +. ./common/reflink
> +
> +# Modify as appropriate.
> +_supported_fs generic
> +
> +_require_scratch_reflink
> +_require_cp_reflink
> +_require_dm_target error
> +_require_command "$KILLALL_PROG" "killall"
> +
> +echo "Silence is golden."
> +
> +_scratch_mkfs >> $seqres.full 2>&1
> +_require_metadata_journaling $SCRATCH_DEV
> +_dmerror_init
> +_dmerror_mount
> +
> +# Create a fs image consuming 1/3 of the scratch fs
> +scratch_freesp_bytes=$(stat -f -c '%a * %S' $SCRATCH_MNT | bc)

_get_available_space $SCRATCH_MNT ?

> +loopimg_bytes=$((scratch_freesp_bytes / 3))
> +
> +loopimg=$SCRATCH_MNT/testfs
> +truncate -s $loopimg_bytes $loopimg
> +_mkfs_dev $loopimg
> +
> +loopmnt=$tmp.mount
> +mkdir -p $loopmnt
> +
> +scratch_aliveflag=$tmp.runsnap
> +snap_aliveflag=$tmp.snapping
> +
> +snap_loop_fs() {
> +	touch "$snap_aliveflag"
> +	while [ -e "$scratch_aliveflag" ]; do
> +		rm -f $loopimg.a
> +		_cp_reflink $loopimg $loopimg.a
> +		sleep 1
> +	done
> +	rm -f "$snap_aliveflag"
> +}
> +
> +fsstress=($FSSTRESS_PROG $FSSTRESS_AVOID -d "$loopmnt" -n 999999 -p "$((LOAD_FACTOR * 4))")
> +
> +for i in $(seq 1 $((25 * TIME_FACTOR)) ); do
> +	touch $scratch_aliveflag
> +	snap_loop_fs >> $seqres.full 2>&1 &
> +
> +	if ! _mount $loopimg $loopmnt -o loop; then
> +		rm -f $scratch_aliveflag
> +		_fail "loop mount failed"

I found it a bit easier to debug if print $i here.

> +		break
> +	fi
> +
> +	("${fsstress[@]}" >> $seqres.full &) > /dev/null 2>&1
> +
> +	# purposely include 0 second sleeps to test shutdown immediately after
> +	# recovery
> +	sleep $((RANDOM % (3 * TIME_FACTOR) ))
> +	rm -f $scratch_aliveflag
> +
> +	# This test aims to simulate sudden disk failure, which means that we
> +	# do not want to quiesce the filesystem or otherwise give it a chance
> +	# to flush its logs.  Therefore we want to call dmsetup with the
> +	# --nolockfs parameter; to make this happen we must call the load
> +	# error table helper *without* 'lockfs'.
> +	_dmerror_load_error_table
> +
> +	ps -e | grep fsstress > /dev/null 2>&1
> +	while [ $? -eq 0 ]; do
> +		$KILLALL_PROG -9 fsstress > /dev/null 2>&1
> +		wait > /dev/null 2>&1
> +		ps -e | grep fsstress > /dev/null 2>&1
> +	done
> +	for ((i = 0; i < 10; i++)); do
> +		test -e "$snap_aliveflag" || break
> +		sleep 1
> +	done
> +
> +	# Mount again to replay log after loading working table, so we have a
> +	# consistent XFS after test.

This is a generic test, fix the XFS specific comments?

> +	$UMOUNT_PROG $loopmnt
> +	_dmerror_unmount || _fail "unmount failed"
> +	_dmerror_load_working_table
> +	if ! _dmerror_mount; then
> +		dmsetup table | tee -a /dev/ttyprintk
> +		lsblk | tee -a /dev/ttyprintk
> +		$XFS_METADUMP_PROG -a -g -o $DMERROR_DEV $seqres.dmfail.md

Above logs all should go to $seqres.full ?

And $XFS_METADUMP_PROG is not suitable for a generic test.

> +		_fail "mount failed"
> +	fi
> +done
> +
> +# Make sure the fs image file is ok
> +if [ -f "$loopimg" ]; then
> +	if _mount $loopimg $loopmnt -o loop; then
> +		$UMOUNT_PROG $loopmnt &> /dev/null
> +	else
> +		echo "final loop mount failed"
> +	fi
> +	_check_xfs_filesystem $loopimg none none

Same here, use _check_scratch_fs?

Thanks,
Eryu

> +fi
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/725.out b/tests/generic/725.out
> new file mode 100644
> index 00000000..ed73a9fc
> --- /dev/null
> +++ b/tests/generic/725.out
> @@ -0,0 +1,2 @@
> +QA output created by 725
> +Silence is golden.