Re: [PATCH] fstests: fix btrfs/255 to fail on deadlock

Eryu Guan
2022-02-20T17:07:43Z

On Wed, Feb 16, 2022 at 11:05:35AM +0100, Gabriel Niebler wrote:
> In its current implementation, the test btrfs/255 would hang forever
> on any kernel w/o patch "btrfs: fix deadlock between quota disable
> and qgroup rescan worker", rather than failing, as it should.
> Fix this by introducing generous timeouts.
>
> Signed-off-by: Gabriel Niebler <gniebler@suse.com>

If deadlock was already triggered, I don't think killing the userspace
program with timeout will help, as the kernel already deadlocked, and
filesystem and/or device can't be used by next test either.

I think we should just exclude the test when running tests on unpatched
kernel.

Thanks,
Eryu

> ---
> tests/btrfs/255 | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/tests/btrfs/255 b/tests/btrfs/255
> index 7e70944a..4c779458 100755
> --- a/tests/btrfs/255
> +++ b/tests/btrfs/255
> @@ -14,6 +14,7 @@ _begin_fstest auto qgroup balance
>
> # real QA test starts here
> _supported_fs btrfs
> +_require_command "$TIMEOUT_PROG" timeout
> _require_scratch
>
> _scratch_mkfs >> $seqres.full 2>&1
> @@ -37,15 +38,23 @@ done
> _btrfs_stress_balance $SCRATCH_MNT >> $seqres.full &
> balance_pid=$!
> echo $balance_pid >> $seqres.full
> +timeout=$((30 * 60))
> for ((i = 0; i < 20; i++)); do
> - $BTRFS_UTIL_PROG quota enable $SCRATCH_MNT
> - $BTRFS_UTIL_PROG quota disable $SCRATCH_MNT
> + $TIMEOUT_PROG -s KILL ${timeout}s $BTRFS_UTIL_PROG quota enable $SCRATCH_MNT
> + [ $? -eq 0 ] || _fail "quota enable timed out"
> + $TIMEOUT_PROG -s KILL ${timeout}s $BTRFS_UTIL_PROG quota disable $SCRATCH_MNT
> + [ $? -eq 0 ] || _fail "quota disable timed out"
> done
> kill $balance_pid &> /dev/null
> -wait
> +
> # wait for the balance operation to finish
> +elapsed=0
> while ps aux | grep "balance start" | grep -qv grep; do
> + if [ $elapsed -gt $timeout ]; then
> + _fail "balance not finished after $timeout seconds"
> + fi
> sleep 1
> + elapsed=$(( ++elapsed ))
> done
>
> echo "Silence is golden"
> --
> 2.35.1