linux-kernel - Re: [PATCH] loop/010: Add test for mode 0 fallocate() on loop devices

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Date:   Fri, 10 Nov 2023 09:27:48 +0800
From:   Yi Zhang <yi.zhang@...hat.com>
To:     Sarthak Kukreti <sarthakkukreti@...omium.org>
Cc:     dm-devel@...ts.linux.dev, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Jens Axboe <axboe@...nel.dk>,
        Mike Snitzer <snitzer@...nel.org>,
        "Darrick J . Wong" <djwong@...nel.org>,
        Christoph Hellwig <hch@....de>,
        Dave Chinner <david@...morbit.com>,
        Brian Foster <bfoster@...hat.com>
Subject: Re: [PATCH] loop/010: Add test for mode 0 fallocate() on loop devices

On Fri, Nov 10, 2023 at 9:02 AM Sarthak Kukreti
<sarthakkukreti@...omium.org> wrote:
>
> A recent patch series[1] adds support for calling fallocate() in mode 0

The patch link is missing in this patch.

> on block devices. This test adds a basic sanity test for loopback devices
> setup on a sparse file and validates that writes to the loopback device
> succeed, even when the underlying filesystem runs out of space.
>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@...omium.org>
> ---
>  tests/loop/010     | 60 ++++++++++++++++++++++++++++++++++++++++++++++
>  tests/loop/010.out |  2 ++
>  2 files changed, 62 insertions(+)
>  create mode 100644 tests/loop/010
>  create mode 100644 tests/loop/010.out
>
> diff --git a/tests/loop/010 b/tests/loop/010
> new file mode 100644
> index 0000000..091be5e
> --- /dev/null
> +++ b/tests/loop/010
> @@ -0,0 +1,60 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-3.0+
> +# Copyright (C) 2023 Google LLC.
> +# Author: sarthakkukret@...gle.com (Sarthak Kukreti)
> +#
> +# Test if fallocate() on a loopback device provisions space on the underlying
> +# filesystem and writes on the loop device succeed, even if the lower
> +# filesystem is filled up.
> +
> +. tests/loop/rc
> +
> +DESCRIPTION="Loop device fallocate() space provisioning"
> +QUICK=1
> +
> +requires() {
> +       _have_program mkfs.ext4
> +}
> +
> +test() {
> +       echo "Running ${TEST_NAME}"
> +
> +       local mount_dir="$TMPDIR/mnt"
> +       mkdir -p ${mount_dir}
> +
> +       local image_file="$TMPDIR/img"
> +       truncate -s 1G "${image_file}"
> +
> +       local loop_device
> +       loop_device="$(losetup -P -f --show "${image_file}")"
> +
> +       mkfs.ext4 ${loop_device} &> /dev/null
> +       mount -t ext4 ${loop_device} ${mount_dir}
> +
> +       local provisioned_file="${mount_dir}/provisioned"
> +       truncate -s 200M "${provisioned_file}"
> +
> +       local provisioned_loop_device
> +       provisioned_loop_device="$(losetup -P -f --show "${provisioned_file}")"
> +
> +       # Provision space for the file: without provisioning support, this fails
> +       # with EOPNOTSUPP.
> +       fallocate -l 200M "${provisioned_loop_device}"
> +
> +       # Fill the filesystem, this command will error out with ENOSPC.
> +       local fs_fill_file="${mount_dir}/fill"
> +       dd if=/dev/zero of="${fs_fill_file}" bs=1M count=1024 status=none &>/dev/null
> +       sync
> +
> +       # Write to provisioned loop device, ensure that it does not run into ENOSPC.
> +       dd if=/dev/zero of="${provisioned_loop_device}" bs=1M count=200 status=none
> +       sync
> +
> +       # Cleanup.
> +       losetup --detach "${provisioned_loop_device}"
> +       umount "${mount_dir}"
> +       losetup --detach "${loop_device}"
> +       rm "${image_file}"
> +
> +       echo "Test complete"
> +}
> \ No newline at end of file
> diff --git a/tests/loop/010.out b/tests/loop/010.out
> new file mode 100644
> index 0000000..068c489
> --- /dev/null
> +++ b/tests/loop/010.out
> @@ -0,0 +1,2 @@
> +Running loop/009
> +Test complete
> --
> 2.42.0.758.gaed0368e0e-goog
>
>


-- 
Best Regards,
  Yi Zhang