Re: [PATCH] tests/xfs: writepage map error unmount test

Eryu Guan
2018-10-28T22:41:26Z

On Tue, Oct 23, 2018 at 02:16:38PM -0400, Brian Foster wrote:
> Certain failures in the page writeback codepath can cause a broader
> writeback (i.e., a sync) sequence to exit prematurely. If this
> occurs during an unmount, it's likely the filesystem will reclaim
> inodes without having cleared all delayed allocation blocks. This
> produces a warning and leaves the filesystem inconsistent.
>
> This test reproduces this scenario using the 'writepage_map'
> errortag. It performs delayed allocation, injects writeback errors
> and immediately unmounts the filesystem.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> ---
>
> Note that this depends on a not yet available error tag.

I'll wait for the "error tag" patch goes in first, or gets some ACKs
first. One really minor issue below.

>
> Brian
>
> tests/xfs/494 | 57 +++++++++++++++++++++++++++++++++++++++++++++++
> tests/xfs/494.out | 2 ++
> tests/xfs/group | 1 +
> 3 files changed, 60 insertions(+)
> create mode 100755 tests/xfs/494
> create mode 100644 tests/xfs/494.out
>
> diff --git a/tests/xfs/494 b/tests/xfs/494
> new file mode 100755
> index 00000000..30877d38
> --- /dev/null
> +++ b/tests/xfs/494
> @@ -0,0 +1,57 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2018 Red Hat, Inc. All Rights Reserved.
> +#
> +# FS QA Test 494
> +#
> +# Simulate a serialization problem between page writeback error handling and
> +# unmount. If ->writepages() fails and returns an error back to the mm
> +# subsystem, writeback of subsequent pages is interrupted and the filesystem
> +# unmounts before processing all dirty pages. This results in unmounting a
> +# filesystem with dirty+delalloc pages, which in turn causes unmount time
> +# warnings and filesystem inconsistency.
> +#
> +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/inject
> +
> +# remove previous $seqres.full before test
> +rm -f $seqres.full
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.
> +_supported_fs generic

Supported fs should be 'xfs' here.

Thanks,
Eryu

> +_supported_os Linux
> +_require_error_injection
> +_require_xfs_io_error_injection "writepage_map"
> +_require_scratch
> +
> +_scratch_mkfs >> $seqres.full 2>&1
> +
> +_scratch_mount
> +_scratch_inject_error "writepage_map" 1
> +# use 512k to dirty multiple pages on large page size systems
> +$XFS_IO_PROG -fc "pwrite 0 512k" $SCRATCH_MNT/file >> $seqres.full 2>&1
> +_scratch_unmount
> +
> +echo Silence is golden
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/494.out b/tests/xfs/494.out
> new file mode 100644
> index 00000000..827c239a
> --- /dev/null
> +++ b/tests/xfs/494.out
> @@ -0,0 +1,2 @@
> +QA output created by 494
> +Silence is golden
> diff --git a/tests/xfs/group b/tests/xfs/group
> index 2cec0585..136d3707 100644
> --- a/tests/xfs/group
> +++ b/tests/xfs/group
> @@ -491,3 +491,4 @@
> 491 auto quick fuzz
> 492 auto quick fuzz
> 493 auto quick fuzz
> +494 auto quick
> --
> 2.17.2
>