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

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Date:   Thu, 9 Nov 2023 22:25:33 -0800
From:   Sarthak Kukreti <sarthakkukreti@...omium.org>
To:     Yi Zhang <yi.zhang@...hat.com>
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

I meant to add a reference to the latest REQ_OP_PROVISION patch series
that this patch accompanied, I'll reword the commit so that it is
clearer:

[1] https://lore.kernel.org/lkml/20231110010139.3901150-1-sarthakkukreti@chromium.org/

Best
Sarthak

On Thu, Nov 9, 2023 at 5:28 PM Yi Zhang <yi.zhang@...hat.com> wrote:
>
> 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
>