Re: [PATCH] fstests: add a another gap extent testcase for btrfs

[Josef Bacik <josef@toxicpanda.com>]

On 2/20/20 11:24 AM, Filipe Manana wrote:
> On Thu, Feb 20, 2020 at 2:39 PM Josef Bacik <josef@toxicpanda.com> wrote:
>>
>> This is a testcase for a corner that I missed when trying to fix gap
>> extents for btrfs.  We would end up with gaps if we hole punched past
>> isize and then extended past the gap in a specific way.  This is a
>> simple reproducer to show the problem, and has been properly fixed by my
>> patches now.
>>
>> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
>> ---
>>   tests/btrfs/204     | 85 +++++++++++++++++++++++++++++++++++++++++++++
>>   tests/btrfs/204.out |  5 +++
>>   tests/btrfs/group   |  1 +
>>   3 files changed, 91 insertions(+)
>>   create mode 100755 tests/btrfs/204
>>   create mode 100644 tests/btrfs/204.out
>>
>> diff --git a/tests/btrfs/204 b/tests/btrfs/204
>> new file mode 100755
>> index 00000000..0d5c4bed
>> --- /dev/null
>> +++ b/tests/btrfs/204
>> @@ -0,0 +1,85 @@
>> +#! /bin/bash
>> +# SPDX-License-Identifier: GPL-2.0
>> +# Copyright (c) 2020 Facebook.  All Rights Reserved.
>> +#
>> +# FS QA Test 204
>> +#
>> +# Validate that without no-holes we do not get a i_size that is after a gap in
>> +# the file extents on disk when punching a hole past i_size.  This is fixed by
>> +# the following patches
>> +#
>> +#      btrfs: use the file extent tree infrastructure
>> +#      btrfs: replace all uses of btrfs_ordered_update_i_size
>> +#
>> +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
>> +. ./common/dmlogwrites
>> +
>> +# remove previous $seqres.full before test
>> +rm -f $seqres.full
>> +
>> +# real QA test starts here
>> +
>> +# Modify as appropriate.
>> +_supported_fs generic
>> +_supported_os Linux
>> +_require_test
>> +_require_scratch
>> +_require_log_writes
> 
> _require_xfs_io_command "falloc" "-k"
> _require_xfs_io_command "fpunch"
> 
>> +
>> +_log_writes_init $SCRATCH_DEV
>> +_log_writes_mkfs "-O ^no-holes" >> $seqres.full 2>&1
>> +
>> +# There's not a straightforward way to commit the transaction without also
>> +# flushing dirty pages, so shorten the commit interval to 1 so we're sure to get
>> +# a commit with our broken file
>> +_log_writes_mount -o commit=1
>> +
>> +# This creates a gap extent because fpunch doesn't insert hole extents past
>> +# i_size
>> +xfs_io -f -c "falloc -k 4k 8k" $SCRATCH_MNT/file
>> +xfs_io -f -c "fpunch 4k 4k" $SCRATCH_MNT/file
>> +
>> +# The pwrite extends the i_size to cover the gap extent, and then the truncate
>> +# sets the disk_i_size to 12k because it assumes everything was a-ok.
>> +xfs_io -f -c "pwrite 0 4k" $SCRATCH_MNT/file | _filter_xfs_io
>> +xfs_io -f -c "pwrite 0 8k" $SCRATCH_MNT/file | _filter_xfs_io
>> +xfs_io -f -c "truncate 12k" $SCRATCH_MNT/file
>> +
>> +# Wait for a transaction commit
>> +sleep 2
>> +
>> +_log_writes_unmount
>> +_log_writes_remove
>> +
>> +cur=$(_log_writes_find_next_fua 0)
>> +echo "cur=$cur" >> $seqres.full
>> +while [ ! -z "$cur" ]; do
>> +       _log_writes_replay_log_range $cur $SCRATCH_DEV >> $seqres.full
>> +
>> +       # We only care about the fs consistency, so just run fsck, we don't have
>> +       # to mount the fs to validate it
>> +       _check_scratch_fs
>> +
>> +       cur=$(_log_writes_find_next_fua $(($cur + 1)))
>> +done
>> +
>> +# success, all done
>> +status=0
>> +exit
>> diff --git a/tests/btrfs/204.out b/tests/btrfs/204.out
>> new file mode 100644
>> index 00000000..44c7c8ae
>> --- /dev/null
>> +++ b/tests/btrfs/204.out
>> @@ -0,0 +1,5 @@
>> +QA output created by 204
>> +wrote 4096/4096 bytes at offset 0
>> +XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
>> +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 6acc6426..7a840177 100644
>> --- a/tests/btrfs/group
>> +++ b/tests/btrfs/group
>> @@ -206,3 +206,4 @@
>>   201 auto quick punch log
>>   202 auto quick subvol snapshot
>>   203 auto quick send clone
>> +204 auto quick log replay
> 
> "prealloc" and "punch" groups as well.
> 
> Since this just tests another variant of the same problem, maybe it
> could be added to btrfs/172, since that test is very recent and you
> authored it as well.
> Anyway, I don't have a strong preference.
> 
> The test itself looks good to me, and with the _require_xfs_io_command
> thing added and the groups (maybe Eryu can add these at commit time):
> 
> Reviewed-by: Filipe Manana <fdmanana@suse.com>
> 

I like to keep these things discrete, if a test is testing two different things 
and it fails I have to go comment out one part and re-run to figure out which 
actually failed.  Thanks,

Josef