Re: [PATCH v4 2/2] generic: new test to check nlink returned by fstat()

[Zorro Lang <zlang@kernel.org>]

On Thu, Jul 30, 2026 at 02:12:38AM +0000, ChenXiaoSong wrote:
> From: ChenXiaoSong <chenxiaosong@kylinos.cn>
> 
> Add a test to verify that fstat(2) returns the expected
> st_nlink value as hardlinks are created and removed.
> 
> Regression test for kernel commit:
> 9dd1964ac59d ("smb/client: fix incorrect nlink returned by fstat()")
> 
> Suggested-by: Zorro Lang <zlang@kernel.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
> ---

This version is good to me now,

Reviewed-by: Zorro Lang <zlang@kernel.org>

(Please To/CC fstests@vger.kernel.org)

>  tests/generic/798     | 59 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/798.out |  2 ++
>  2 files changed, 61 insertions(+)
>  create mode 100755 tests/generic/798
>  create mode 100644 tests/generic/798.out
> 
> diff --git a/tests/generic/798 b/tests/generic/798
> new file mode 100755
> index 00000000..e48a69a1
> --- /dev/null
> +++ b/tests/generic/798
> @@ -0,0 +1,59 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2026 KylinSoft Co., Ltd. All rights reserved.
> +# Author(s): ChenXiaoSong <chenxiaosong@kylinos.cn>
> +#
> +# FS QA Test 798
> +#
> +# Check that fstat(2) returns the correct hard link count for a regular file.
> +#
> +#  from
> +#  tests/generic/002
> +#  Copyright (c) 2000-2001 Silicon Graphics, Inc.  All Rights Reserved.
> +#
> +. ./common/preamble
> +_begin_fstest metadata auto quick hardlink
> +
> +_cleanup()
> +{
> +	cd /
> +	rm -rf "$tmp".* "$testdir"
> +}
> +
> +_require_test
> +_require_hardlinks
> +
> +_fixed_by_fs_commit cifs 9dd1964ac59d \
> +	"smb/client: fix incorrect nlink returned by fstat()"
> +
> +_get_nlink()
> +{
> +	# This calls `fstat()`, see `stat_f()` in xfsprogs-dev.git io/stat.c:
> +	# https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git/tree/io/stat.c
> +	$XFS_IO_PROG -c 'stat -r' "$1" |
> +		sed -n 's/^stat\.nlink = //p'
> +}
> +
> +testdir=$TEST_DIR/$seq
> +rm -rf "$testdir"
> +mkdir "$testdir"
> +
> +touch "$testdir/tmp.1"
> +for ((l = 2; l <= 20; l++)); do
> +	ln "$testdir/tmp.1" "$testdir/tmp.$l"
> +	nlink=$(_get_nlink "$testdir/tmp.1")
> +	if [ "$nlink" != "$l" ]; then
> +		_fail "Expected nlink $l after creating link $testdir/tmp.$l, got ${nlink:-nothing}"
> +	fi
> +done
> +
> +for ((l = 20; l >= 1; l--)); do
> +	nlink=$(_get_nlink "$testdir/tmp.1")
> +	if [ "$nlink" != "$l" ]; then
> +		_fail "Expected nlink $l before removing link $testdir/tmp.$l, got ${nlink:-nothing}"
> +	fi
> +	rm -f "$testdir/tmp.$l"
> +done
> +
> +echo "Silence is golden"
> +_exit 0
> diff --git a/tests/generic/798.out b/tests/generic/798.out
> new file mode 100644
> index 00000000..216d6e93
> --- /dev/null
> +++ b/tests/generic/798.out
> @@ -0,0 +1,2 @@
> +QA output created by 798
> +Silence is golden
> -- 
> 2.43.0
>