Re: [PATCH 2/2] xfs: add mount test for read only log devices

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

On Fri, Apr 25, 2025 at 09:03:23AM +0000, Hans Holmberg wrote:
> Make sure that we can mount log devices read-only if them themselves
> are marked as read-only.
> 
> Also make sure that rw re-mounts are not allowed if the device is
> marked as read-only.
> 
> Based on generic/050.
> 
> Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
> ---
>  tests/xfs/838     | 55 +++++++++++++++++++++++++++++++++++++++++++++++
>  tests/xfs/838.out | 10 +++++++++
>  2 files changed, 65 insertions(+)
>  create mode 100755 tests/xfs/838
>  create mode 100644 tests/xfs/838.out
> 
> diff --git a/tests/xfs/838 b/tests/xfs/838
> new file mode 100755
> index 000000000000..93a39a7ec8e9
> --- /dev/null
> +++ b/tests/xfs/838
> @@ -0,0 +1,55 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2009 Christoph Hellwig.
> +# Copyright (c) 2025 Western Digital Corporation.
> +#
> +# FS QA Test No. 838
> +#
> +# Check out various mount/remount/unmount scenarious on a read-only logdev
> +# Based on generic/050
> +#
> +. ./common/preamble
> +_begin_fstest mount auto quick
> +
> +_cleanup_setrw()
> +{
> +	cd /
> +	blockdev --setrw $SCRATCH_LOGDEV
> +}
> +
> +# Import common functions.
> +. ./common/filter
> +
> +_require_logdev
> +_require_local_device $SCRATCH_LOGDEV
> +_register_cleanup "_cleanup_setrw"
> +
> +_scratch_mkfs >/dev/null 2>&1
> +
> +#
> +# Mark the log device read-only
> +#
> +echo "setting device read-only"
> +blockdev --setro $SCRATCH_LOGDEV
> +
> +#
> +# Mount and make sure it can't be written to.
> +#
> +echo "mounting read-only log block device:"
> +_scratch_mount 2>&1 | _filter_ro_mount | _filter_scratch
> +if [ "${PIPESTATUS[0]}" -eq 0 ]; then
> +	echo "writing to file on read-only filesystem:"
> +	dd if=/dev/zero of=$SCRATCH_MNT/foo bs=1M count=1 oflag=direct 2>&1 | _filter_scratch

As I mentioned over in the other thread, perhaps this test should check
that a readonly log device results in a norecovery mount and that
pending changes don't show up if the mount succeeds?

Also, ext4 supports external log devices, should this be in
tests/generic?

--D

> +else
> +	_fail "failed to mount"
> +fi
> +
> +echo "remounting read-write:"
> +_scratch_remount rw 2>&1 | _filter_scratch | _filter_ro_mount
> +
> +echo "unmounting read-only filesystem"
> +_scratch_unmount 2>&1 | _filter_scratch | _filter_ending_dot
> +
> +# success, all done
> +echo "*** done"
> +status=0
> diff --git a/tests/xfs/838.out b/tests/xfs/838.out
> new file mode 100644
> index 000000000000..673b48f42a4e
> --- /dev/null
> +++ b/tests/xfs/838.out
> @@ -0,0 +1,10 @@
> +QA output created by 838
> +setting device read-only
> +mounting read-only log block device:
> +mount: device write-protected, mounting read-only
> +writing to file on read-only filesystem:
> +dd: failed to open 'SCRATCH_MNT/foo': Read-only file system
> +remounting read-write:
> +mount: cannot remount device read-write, is write-protected
> +unmounting read-only filesystem
> +*** done
> -- 
> 2.34.1
>