Re: [PATCH v2] generic: test fsync of directory with renamed symlink

[Filipe Manana <fdmanana@kernel.org>]

On Mon, May 09, 2022 at 11:31:58PM +0800, Zorro Lang wrote:
> On Mon, May 09, 2022 at 03:31:02PM +0100, fdmanana@kernel.org wrote:
> > From: Filipe Manana <fdmanana@suse.com>
> > 
> > Test that if we fsync a directory, create a symlink inside it, rename
> > the symlink, fsync again the directory and then power fail, after the
> > filesystem is mounted again, the symlink exists with the new name and
> > it has the correct content.
> > 
> > This currently fails on btrfs, because the symlink ends up empty (which
> > is illegal on Linux), but it is fixed by kernel commit:
> > 
> >     d0e64a981fd841 ("btrfs: always log symlinks in full mode")
> > 
> > Reviewed-by: David Disseldorp <ddiss@suse.de>
> > Signed-off-by: Filipe Manana <fdmanana@suse.com>
> > ---
> > 
> > v2: Rebased on latest for-next, quoted $SCRATCH_MNT references (David Disseldorp)
> >     and added David's review tag.
> 
> This case is nearly copied from generic/066, so there's not debatable things

I think you mean the part of setting the special mount option for f2fs, right?

Because otherwise 066 is very different (testing xattrs and not symlink stuff).

> from code format. It's in my local testing branch now, and will be pushed in
> next release, after regression test done. Thanks for this new test.

Thanks!

> 
> Zorro
> 
> > 
> >  tests/generic/690     | 90 +++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/690.out |  2 +
> >  2 files changed, 92 insertions(+)
> >  create mode 100755 tests/generic/690
> >  create mode 100644 tests/generic/690.out
> > 
> > diff --git a/tests/generic/690 b/tests/generic/690
> > new file mode 100755
> > index 00000000..f03295a5
> > --- /dev/null
> > +++ b/tests/generic/690
> > @@ -0,0 +1,90 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2022 SUSE Linux Products GmbH.  All Rights Reserved.
> > +#
> > +# FS QA Test 690
> > +#
> > +# Test that if we fsync a directory, create a symlink inside it, rename the
> > +# symlink, fsync again the directory and then power fail, after the filesystem
> > +# is mounted again, the symlink exists with the new name and it has the correct
> > +# content.
> > +#
> > +# On btrfs this used to result in the symlink being empty (i_size 0), and it was
> > +# fixed by kernel commit:
> > +#
> > +#    d0e64a981fd841 ("btrfs: always log symlinks in full mode")
> > +#
> > +. ./common/preamble
> > +_begin_fstest auto quick log
> > +
> > +_cleanup()
> > +{
> > +	_cleanup_flakey
> > +	cd /
> > +	rm -r -f $tmp.*
> > +}
> > +
> > +. ./common/rc
> > +. ./common/filter
> > +. ./common/dmflakey
> > +
> > +# real QA test starts here
> > +
> > +_supported_fs generic
> > +_require_scratch
> > +_require_symlinks
> > +_require_dm_target flakey
> > +
> > +rm -f $seqres.full
> > +
> > +# f2fs doesn't support fs-op level transaction functionality, so it has no way
> > +# to persist all metadata updates in one transaction. We have to use its mount
> > +# option "fastboot" so that it triggers a metadata checkpoint to persist all
> > +# metadata updates that happen before a fsync call. Without this, after the
> > +# last fsync in the test, the symlink named "baz" will not exist.
> > +if [ $FSTYP = "f2fs" ]; then
> > +	export MOUNT_OPTIONS="-o fastboot $MOUNT_OPTIONS"
> > +fi
> > +
> > +_scratch_mkfs >>$seqres.full 2>&1
> > +_require_metadata_journaling $SCRATCH_DEV
> > +_init_flakey
> > +_mount_flakey
> > +
> > +# Create our test directory.
> > +mkdir "$SCRATCH_MNT"/testdir
> > +
> > +# Commit the current transaction and persist the directory.
> > +sync
> > +
> > +# Create a file in the test directory, so that the next fsync on the directory
> > +# actually does something (it logs the directory).
> > +echo -n > "$SCRATCH_MNT"/testdir/foo
> > +
> > +# Fsync the directory.
> > +$XFS_IO_PROG -c "fsync" "$SCRATCH_MNT"/testdir
> > +
> > +# Now create a symlink inside the test directory.
> > +ln -s "$SCRATCH_MNT"/testdir/foo "$SCRATCH_MNT"/testdir/bar
> > +
> > +# Rename the symlink.
> > +mv "$SCRATCH_MNT"/testdir/bar "$SCRATCH_MNT"/testdir/baz
> > +
> > +# Fsync again the directory.
> > +$XFS_IO_PROG -c "fsync" "$SCRATCH_MNT"/testdir
> > +
> > +# Simulate a power failure and then mount again the filesystem to replay the
> > +# journal/log.
> > +_flakey_drop_and_remount
> > +
> > +# The symlink should exist, with the name "baz" and its content must be
> > +# "$SCRATCH_MNT/testdir/foo".
> > +[ -L "$SCRATCH_MNT"/testdir/baz ] || echo "symlink 'baz' is missing"
> > +symlink_content=$(readlink "$SCRATCH_MNT"/testdir/baz | _filter_scratch)
> > +echo "symlink content: ${symlink_content}"
> > +
> > +_unmount_flakey
> > +
> > +# success, all done
> > +status=0
> > +exit
> > diff --git a/tests/generic/690.out b/tests/generic/690.out
> > new file mode 100644
> > index 00000000..84be1247
> > --- /dev/null
> > +++ b/tests/generic/690.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 690
> > +symlink content: SCRATCH_MNT/testdir/foo
> > -- 
> > 2.35.1
> >