Re: [PATCH 1/2] xfs: make sure syncfs(2) passes back super_operations.sync_fs errors

[Zorro Lang <zlang@redhat.com>]

On Tue, Apr 19, 2022 at 10:32:15AM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
> 
> This is a regression test to make sure that nonzero error returns from
> a filesystem's ->sync_fs implementation are actually passed back to
> userspace when the call stack involves syncfs(2).
> 
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> Reviewed-by: Zorro Lang <zlang@redhat.com>
> ---
>  tests/xfs/839     |   42 ++++++++++++++++++++++++++++++++++++++++++
>  tests/xfs/839.out |    2 ++
>  2 files changed, 44 insertions(+)
>  create mode 100755 tests/xfs/839
>  create mode 100644 tests/xfs/839.out
> 
> 
> diff --git a/tests/xfs/839 b/tests/xfs/839
> new file mode 100755
> index 00000000..9bfe93ef
> --- /dev/null
> +++ b/tests/xfs/839
> @@ -0,0 +1,42 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2022 Oracle.  All Rights Reserved.
> +#
> +# FS QA Test No. 839
> +#
> +# Regression test for kernel commits:
> +#
> +# 5679897eb104 ("vfs: make sync_filesystem return errors from ->sync_fs")
> +# 2d86293c7075 ("xfs: return errors in xfs_fs_sync_fs")
> +#
> +# During a code inspection, I noticed that sync_filesystem ignores the return
> +# value of the ->sync_fs calls that it makes.  sync_filesystem, in turn is used
> +# by the syncfs(2) syscall to persist filesystem changes to disk.  This means
> +# that syncfs(2) does not capture internal filesystem errors that are neither
> +# visible from the block device (e.g. media error) nor recorded in s_wb_err.
> +# XFS historically returned 0 from ->sync_fs even if there were log failures,
> +# so that had to be corrected as well.
> +#
> +# The kernel commits above fix this problem, so this test tries to trigger the
> +# bug by using the shutdown ioctl on a clean, freshly mounted filesystem in the
> +# hope that the EIO generated as a result of the filesystem being shut down is
> +# only visible via ->sync_fs.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick shutdown
> +
> +# real QA test starts here
> +
> +# Modify as appropriate.

Good to me, we can help to add the missing "_supported_fs xfs", if you don't
like to send a new version for that again.

Reviewed-by: Zorro Lang <zlang@redhat.com>

> +_require_xfs_io_command syncfs
> +_require_scratch_nocheck
> +_require_scratch_shutdown
> +
> +# Reuse the fs formatted when we checked for the shutdown ioctl, and don't
> +# bother checking the filesystem afterwards since we never wrote anything.
> +_scratch_mount
> +$XFS_IO_PROG -x -c 'shutdown -f ' -c syncfs $SCRATCH_MNT
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/839.out b/tests/xfs/839.out
> new file mode 100644
> index 00000000..f275cdcc
> --- /dev/null
> +++ b/tests/xfs/839.out
> @@ -0,0 +1,2 @@
> +QA output created by 839
> +syncfs: Input/output error
>