Re: [PATCH v4 6/6] f2fs/009: detect and repair nlink corruption

[Dave Chinner <david@fromorbit.com>]

On Wed, Mar 12, 2025 at 03:23:09PM +0800, Chao Yu wrote:
> This is a regression test to check whether fsck can handle corrupted
> nlinks correctly, it uses inject.f2fs to inject nlinks w/ wrong value,
> and expects fsck.f2fs can detect such corruption and do the repair.
> 
> Cc: Jaegeuk Kim <jaegeuk@kernel.org>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> v4:
> - remove unnecessary "_require_command fsck.f2fs"
> - clean up _fixed_by_git_commit line
> - fix to clean all tmp files in _cleanup
>  tests/f2fs/009     | 147 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/f2fs/009.out |   2 +
>  2 files changed, 149 insertions(+)
>  create mode 100755 tests/f2fs/009
>  create mode 100644 tests/f2fs/009.out
> 
> diff --git a/tests/f2fs/009 b/tests/f2fs/009
> new file mode 100755
> index 00000000..9120d8a5
> --- /dev/null
> +++ b/tests/f2fs/009
> @@ -0,0 +1,147 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2025 Chao Yu.  All Rights Reserved.
> +#
> +# FS QA Test No. f2fs/009
> +#
> +# This is a regression test to check whether fsck can handle corrupted
> +# nlinks correctly, it uses inject.f2fs to inject nlinks w/ wrong value,
> +# and expects fsck.f2fs can detect such corruption and do the repair.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick
> +
> +if [ ! -x "$(type -P socket)" ]; then
> +	_notrun "Couldn't find socket"
> +fi
> +
> +_require_scratch
> +_require_command "$F2FS_INJECT_PROG" inject.f2fs
> +
> +_fixed_by_git_commit f2fs-tools 958cd6e \
> +	"fsck.f2fs: support to repair corrupted i_links"
> +
> +filename=$SCRATCH_MNT/foo
> +hardlink=$SCRATCH_MNT/bar
> +
> +_cleanup()
> +{
> +	if [ -n "$pid" ]; then
> +		kill $pid &> /dev/null
> +		wait
> +	fi
> +	cd /
> +	rm -r -f $tmp.*
> +}
> +
> +for ((i=0;i<14;i++)) do
> +	echo "round: " $i >> $seqres.full
> +
> +	_scratch_mkfs >> $seqres.full
> +	_scratch_mount
> +
> +	if [ $i == 0 ]; then
> +		touch $filename
> +		ino=`stat -c '%i' $filename`
> +		nlink=0
> +	elif [ $i == 1 ]; then
.....

Ok, it works, but it's a bit nasty. You want to run the same
injection and checking on all types of inodes, so factor that out
like so:

inject_and_check()
{
	local nlink=$1
	local ino=`stat -c '%i' $filename`

	echo "ino:"$ino >> $seqres.full
	echo "nlink:"$nlink >> $seqres.full

	_scratch_unmount

	$F2FS_INJECT_PROG --node --mb i_links --nid $ino --val $nlink $SCRATCH_DEV \
		>> $seqres.full || _fail "fail to inject"

	_check_scratch_fs >> $seqres.full 2>&1 && _fail "can't find corruption"
	_repair_scratch_fs >> $seqres.full
	_check_scratch_fs >> $seqres.full 2>&1 || _fail "fsck can't fix corruption"

	_scratch_mount
	_scratch_unmount

	_scratch_mkfs >> $seqres.full
	_scratch_mount
}

And now most of the test cases become this:

_scratch_mkfs >> $seqres.full
_scratch_mount

touch $filename
inject_and_check 0

mkdir $filename
inject_and_check 1

mknod $filename c 9 0
inject_and_check 0

mknod $filename b 8 0
inject_and_check 0

.....

The whacky cases with socket and orphan inodes can be handled
by factoring inject_and_check so there's a second function that
takes both ino and nlink as parameters.

This gets rid of all the unnecessary if/elif logic and looping, 
leaving only the test code that does the work behind.

-Dave.
-- 
Dave Chinner
david@fromorbit.com