Re: [PATCH v2] btrfs: test a directory fsync scenaro after replacing a subdir with a file

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

On Tue, Mar 03, 2026 at 06:07:33PM +0000, fdmanana@kernel.org wrote:
> From: Filipe Manana <fdmanana@suse.com>
> 
> Test a scenario where we remove a directory previously persisted, create
> a file with the same name and parent directory, create two directories in
> the same parent directory, create a hard link for the new file in one of
> the new directories, fsync the directory with the hard link and fsync the
> parent directory. After a power failure we expect both directories to be
> persisted as well as the new file and its hard link.
> 
> This exercises a bug on btrfs fixed by the following kernel patch:
> 
>   "btrfs: log new dentries when logging parent dir of a conflicting inode"
> 
> Signed-off-by: Filipe Manana <fdmanana@suse.com>
> ---
> 
> V2: Add missing scratch filter for the ls output.

Looks good to me now,
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D

> 
>  tests/generic/790     | 70 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/790.out | 12 ++++++++
>  2 files changed, 82 insertions(+)
>  create mode 100755 tests/generic/790
>  create mode 100644 tests/generic/790.out
> 
> diff --git a/tests/generic/790 b/tests/generic/790
> new file mode 100755
> index 00000000..c9bac6d0
> --- /dev/null
> +++ b/tests/generic/790
> @@ -0,0 +1,70 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2026 SUSE S.A.  All Rights Reserved.
> +#
> +# FS QA Test 790
> +#
> +# Test a scenario where we remove a directory previously persisted, create a
> +# file with the same name and parent directory, create two directories in the
> +# same parent directory, create a hard link for the new file in one of the
> +# new directories, fsync the directory with the hard link and fsync the parent
> +# directory. After a power failure we expect both directories to be persisted
> +# as well as the new file and its hard link.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick log
> +
> +_cleanup()
> +{
> +	_cleanup_flakey
> +	cd /
> +	rm -r -f $tmp.*
> +}
> +
> +. ./common/filter
> +. ./common/dmflakey
> +
> +_require_scratch
> +_require_dm_target flakey
> +
> +[ "$FSTYP" = "btrfs" ] && _fixed_by_kernel_commit xxxxxxxxxxxx \
> +	"btrfs: log new dentries when logging parent dir of a conflicting inode"
> +
> +_scratch_mkfs >>$seqres.full 2>&1 || _fail "mkfs failed"
> +_require_metadata_journaling $SCRATCH_DEV
> +_init_flakey
> +_scratch_mount
> +
> +mkdir $SCRATCH_MNT/foo
> +
> +_scratch_sync
> +
> +rmdir $SCRATCH_MNT/foo
> +
> +# Create two new directories in the same parent directory as the new file.
> +mkdir $SCRATCH_MNT/dir1
> +mkdir $SCRATCH_MNT/dir2
> +
> +# Create a file with the name of the directly we deleted and was persisted
> +# before.
> +touch $SCRATCH_MNT/foo
> +
> +# Create a hard link for the new file inside one of the new directories.
> +ln $SCRATCH_MNT/foo $SCRATCH_MNT/dir2/link
> +
> +$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/dir2
> +$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/
> +
> +# Simulate a power failure and then mount again the filesystem to replay the
> +# journal/log.
> +_flakey_drop_and_remount
> +
> +# We expect to see dir1, dir2, file foo and its hard link, since dir2 was
> +# explicitly fsynced as well as the parent directory.
> +echo -e "Filesystem content after power failure:\n"
> +# Exclude 'lost+found' dir from ext4 and last line if it's blank (due to removal
> +# of 'lost+found').
> +ls -R $SCRATCH_MNT/ | grep -v 'lost+found' | sed -e '${/^$/d;}' | _filter_scratch
> +
> +# success, all done
> +_exit 0
> diff --git a/tests/generic/790.out b/tests/generic/790.out
> new file mode 100644
> index 00000000..d9c0592d
> --- /dev/null
> +++ b/tests/generic/790.out
> @@ -0,0 +1,12 @@
> +QA output created by 790
> +Filesystem content after power failure:
> +
> +SCRATCH_MNT/:
> +dir1
> +dir2
> +foo
> +
> +SCRATCH_MNT/dir1:
> +
> +SCRATCH_MNT/dir2:
> +link
> -- 
> 2.47.2
> 
>