Re: [PATCH v2 15/16] generic: add race test that mmap write to source of reflink

["Darrick J. Wong" <djwong@kernel.org>]

On Thu, Nov 25, 2021 at 03:47:51PM +0800, Shiyang Ruan wrote:
> Test for races or FS corruption when mmap writing to a file that's also
> the source of a reflink operation. (MMAP version of generic/167,166)
> 
> Signed-off-by: Shiyang Ruan <ruansy.fnst@fujitsu.com>
> ---
>  tests/generic/914     | 64 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/914.out |  4 +++
>  2 files changed, 68 insertions(+)
>  create mode 100755 tests/generic/914
>  create mode 100644 tests/generic/914.out
> 
> diff --git a/tests/generic/914 b/tests/generic/914
> new file mode 100755
> index 00000000..c51c44c7
> --- /dev/null
> +++ b/tests/generic/914
> @@ -0,0 +1,64 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# FS QA Test No. 914
> +#
> +# Test for races or FS corruption when mmap writing to a file that's also
> +# the source of a reflink operation. (MMAP version of generic/167,166)
> +#
> +. ./common/preamble
> +_begin_fstest auto clone
> +
> +_register_cleanup "_cleanup" BUS
> +
> +# Import common functions.
> +. ./common/filter
> +. ./common/reflink
> +
> +# real QA test starts here
> +_require_scratch_reflink
> +_require_cp_reflink
> +
> +echo "Format and mount"
> +_scratch_mkfs > $seqres.full 2>&1
> +_scratch_mount >> $seqres.full 2>&1
> +
> +testdir=$SCRATCH_MNT/test-$seq
> +finished_file=/tmp/finished
> +rm -rf $finished_file
> +mkdir $testdir
> +
> +loops=1024
> +nr_loops=$((loops - 1))
> +blksz=65536
> +
> +echo "Initialize file"
> +echo >> $seqres.full
> +_pwrite_byte 0x61 0 $((loops * blksz)) $testdir/file1 >> $seqres.full
> +_scratch_cycle_mount
> +
> +# Snapshot creator...
> +snappy() {
> +	n=0
> +	while [ ! -e $finished_file ]; do
> +		out="$(_cp_reflink $testdir/file1 $testdir/snap_$n 2>&1)"

Just out of curiosity, did you notice any of the slow-writes effects
that caused Dave to add throttling to generic/166?  I'm kinda assuming
no since he only changed the directio write tester, but <shrug> now
you're the expert in this area. ;)

In any case, looks correct to me, so
Reviewed-by: Darrick J. Wong <djwong@kernel.org>

--D

> +		res=$?
> +		echo "$out" | grep -q "No space left" && break
> +		test -n "$out" && echo "$out"
> +		test $res -ne 0 && break
> +		n=$((n + 1))
> +	done
> +}
> +
> +echo "Snapshot a file undergoing mmap rewrite"
> +snappy &
> +seq $nr_loops -1 0 | while read i; do
> +	$XFS_IO_PROG -f -c "mmap -rw $((i * blksz)) $blksz" \
> +		-c "mwrite -S 0x63 $((i * blksz)) $blksz" $testdir/file1 >> $seqres.full
> +done
> +touch $finished_file
> +wait
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/914.out b/tests/generic/914.out
> new file mode 100644
> index 00000000..1472055f
> --- /dev/null
> +++ b/tests/generic/914.out
> @@ -0,0 +1,4 @@
> +QA output created by 914
> +Format and mount
> +Initialize file
> +Snapshot a file undergoing mmap rewrite
> -- 
> 2.34.0
> 
> 
>