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Date:   Fri, 5 May 2023 15:39:29 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Anna Schumaker <anna@kernel.org>
Cc:     linux-nfs@vger.kernel.org, fstests@vger.kernel.org
Subject: Re: [PATCH v2] generic/728: Add a test for xattr ctime updates
Message-ID: <20230505223929.GA15384@frogsfrogsfrogs>
References: <20230505172427.94963-1-anna@kernel.org>
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On Fri, May 05, 2023 at 01:24:27PM -0400, Anna Schumaker wrote:
> From: Anna Schumaker <Anna.Schumaker@Netapp.com>
> 
> The NFS client wasn't updating ctime after a setxattr request. This is a
> test written while fixing the bug.
> 
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> 
> ---
> v2:
>  - Move test to generic/
>  - Address comments from the mailing list
> ---
>  tests/generic/728     | 42 ++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/728.out |  2 ++
>  2 files changed, 44 insertions(+)
>  create mode 100755 tests/generic/728
>  create mode 100644 tests/generic/728.out
> 
> diff --git a/tests/generic/728 b/tests/generic/728
> new file mode 100755
> index 000000000000..ab2414c151db
> --- /dev/null
> +++ b/tests/generic/728
> @@ -0,0 +1,42 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2023 Netapp Inc., All Rights Reserved.
> +#
> +# FS QA Test 728
> +#
> +# Test a bug where the NFS client wasn't sending a post-op GETATTR to the
> +# server after setting an xattr, resulting in `stat` reporting a stale ctime.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick attr
> +
> +# Import common functions
> +. ./common/attr
> +
> +# real QA test starts here
> +_supported_fs generic
> +_require_test
> +_require_attrs
> +
> +rm -rf $TEST_DIR/testfile
> +touch $TEST_DIR/testfile
> +
> +
> +_check_xattr_op()
> +{
> +  what=$1
> +  shift 1
> +
> +  before_ctime=$(stat -c %z $TEST_DIR/testfile)
> +  $SETFATTR_PROG $* $TEST_DIR/testfile
> +  after_ctime=$(stat -c %z $TEST_DIR/testfile)

What happens if the filesystem's timestamp granularity isn't sufficient
to capture a difference across a setxattr operation?  Most of the time
we only update the (fast) timestamps at every clock tick, right?

--D

> +
> +  test "$before_ctime" != "$after_ctime" || echo "Expected ctime to change after $what."
> +}
> +
> +_check_xattr_op setxattr -n user.foobar -v 123
> +_check_xattr_op removexattr -x user.foobar
> +
> +echo "Silence is golden"
> +status=0
> +exit
> diff --git a/tests/generic/728.out b/tests/generic/728.out
> new file mode 100644
> index 000000000000..ab39f45fe5da
> --- /dev/null
> +++ b/tests/generic/728.out
> @@ -0,0 +1,2 @@
> +QA output created by 728
> +Silence is golden
> -- 
> 2.40.1
>