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

[Brian Foster <bfoster@redhat.com>]

On Sun, Oct 28, 2018 at 09:56:33PM +0800, Eryu Guan wrote:
> 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.
> 

Yep. I probably should have been more clear and/or set this RFC. This
test is wholly dependent on if/whether/how to deal with the associated
error handling issue, which atm is still up in the air. The tag/test is
primarily to demonstrate the problem and may not be independently useful
until there's a supporting fix. I may float a patch for that soon..

> > 
> > 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.
> 

Will fix, thanks.

Brian

> 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
> >