Re: [PATCH v2] fstests: Vertify dir permissions when creating a stub subvolume

[Josef Bacik <josef@toxicpanda.com>]

On Sun, Aug 13, 2023 at 10:13:42PM -0700, Lee Trager wrote:
> btrfs supports creating nesting subvolumes however snapshots are not
> recurive. When a snapshot is taken of a volume which contains a subvolume
> the subvolume is replaced with a stub subvolume which has the same name and
> uses inode number 2. This test validates that the stub volume copies
> permissions of the original volume.
> Signed-off-by: Lee Trager <lee@trager.us>
> ---
> v2:
> - Migrated _require_unshare from overlay/020 into common_rc. Updated the error
>   message as most Linux systems should have unshare from util-linux.
> - Added note about why the test must be done in one subshell process.
> - chown command now uses $qa_user:$qa_group instead of hard coded values.
> common/rc           |  6 ++++++
>  tests/btrfs/300     | 46 +++++++++++++++++++++++++++++++++++++++++++++
>  tests/btrfs/300.out | 18 ++++++++++++++++++
>  tests/overlay/020   |  7 +------
>  4 files changed, 71 insertions(+), 6 deletions(-)
>  create mode 100755 tests/btrfs/300
>  create mode 100644 tests/btrfs/300.out
> 
> diff --git a/common/rc b/common/rc
> index 5c4429ed..ca7c5c14 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -5224,6 +5224,12 @@ _soak_loop_running() {
>  	return 0
>  }
>  
> +
> +_require_unshare() {
> +	unshare -f -r -m -p -U  true &>/dev/null || \
> +		_notrun "unshare $@: not found, should be in util-linux"
> +}
> +
>  init_rc
>  
>  ################################################################################
> diff --git a/tests/btrfs/300 b/tests/btrfs/300
> new file mode 100755
> index 00000000..c86ed268
> --- /dev/null
> +++ b/tests/btrfs/300
> @@ -0,0 +1,46 @@
> +#!/bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2022 Meta Platforms, Inc.  All Rights Reserved.
> +#
> +# FS QA Test 300
> +#
> +# Validate that snapshots taken while in a remapped namespace preserve
> +# the permissions of the user.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick subvol snapshot
> +
> +_supported_fs btrfs
> +
> +_require_test
> +_require_user
> +_require_group
> +_require_unix_perm_checking
> +_require_unshare
> +_register_cleanup "cleanup"
> +
> +test_dir="${TEST_DIR}/$(basename $0)"
> +cleanup() {
> +    [ -d "$test_dir" ] && rm -rf $test_dir
> +}
> +
> +mkdir $test_dir
> +chown $qa_user:$qa_group $test_dir
> +
> +# _user_do executes each command as $qa_user in its own subshell. unshare
> +# sets the namespace for the running shell. The test must run in one user
> +# subshell to preserve the namespace over multiple commands.
> +_user_do "
> +cd ${test_dir};
> +unshare --user --keep-caps --map-auto --map-root-user;
> +$BTRFS_UTIL_PROG subvolume create subvol;
> +touch subvol/{1,2,3};
> +$BTRFS_UTIL_PROG subvolume create subvol/subsubvol;
> +touch subvol/subsubvol/{4,5,6};
> +$BTRFS_UTIL_PROG subvolume snapshot subvol snapshot;
> +"
> +
> +find $test_dir -printf "%M %u %g %P\n"
> +
> +status=0
> +exit
> diff --git a/tests/btrfs/300.out b/tests/btrfs/300.out
> new file mode 100644
> index 00000000..33b5fb44
> --- /dev/null
> +++ b/tests/btrfs/300.out
> @@ -0,0 +1,18 @@
> +QA output created by 300
> +Create subvolume './subvol'
> +Create subvolume 'subvol/subsubvol'
> +Create a snapshot of 'subvol' in './snapshot'
> +drwxr-xr-x fsgqa fsgqa 

There's an extra whitespace here, did it come from the output or is it
extraneous?  Either way it should probably be removed.  Thanks,

Josef