Re: [PATCH] btrfs: regression test for subvol deletion after rename

[Josef Bacik <josef@xxxxxxxxxxxxxx>]

On 12/19/19 11:12 AM, Nikolay Borisov wrote:
> On 19.12.19 г. 16:28 ч., Josef Bacik wrote:
> > Test removal of a subvolume via rmdir after it has been renamed into a
> > snapshot of the volume that originally contained the subvolume
> > reference.
> >
> > This currently fails on btrfs but is fixed by the patch with the title
> >
> >    "btrfs: fix invalid removal of root ref"
> >
> > Signed-off-by: Josef Bacik <josef@xxxxxxxxxxxxxx>
> > ---
> >   tests/btrfs/202     | 54 +++++++++++++++++++++++++++++++++++++++++++++
> >   tests/btrfs/202.out |  4 ++++
> >   tests/btrfs/group   |  1 +
> >   3 files changed, 59 insertions(+)
> >   create mode 100755 tests/btrfs/202
> >   create mode 100644 tests/btrfs/202.out
> >
> > diff --git a/tests/btrfs/202 b/tests/btrfs/202
> > new file mode 100755
> > index 00000000..b02ee446
> > --- /dev/null
> > +++ b/tests/btrfs/202
> > @@ -0,0 +1,54 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +#
> > +# FS QA Test 201
> > +#
> > +# Regression test for fix "btrfs: fix invalid removal of root ref"
> > +#
> > +seq=`basename $0`
> > +seqres=$RESULT_DIR/$seq
> > +echo "QA output created by $seq"
> > +
> > +here=`pwd`
> > +tmp=/tmp/$$
> > +status=1	# failure is the default!
> > +trap "_cleanup; exit \$status" 0 1 2 3 15
> > +
> > +_cleanup()
> > +{
> > +	cd /
> > +	rm -f $tmp.*
> > +}
> > +
> > +. ./common/rc
> > +. ./common/filter
> > +
> > +rm -f $seqres.full
> > +
> > +_supported_fs btrfs
> > +_supported_os Linux
> > +
> > +_scratch_mkfs >> $seqres.full 2>&1
> > +_scratch_mount
> > +
> > +# Create a subvol b under a and then snapshot a into c.  This create's a stub
> > +# entry in c for b because c doesn't have a reference for b.
> > +#
> > +# But when we rename b c/foo it creates a ref for b in c.  However if we go to
> > +# remove c/b btrfs used to depend on not finding the root ref to handle the
> > +# unlink properly, but we now have a ref for that root.  We also had a bug that
> > +# would allow us to remove mis-matched refs if the keys matched, so we'd end up
> > +# removing too many entries which would cause a transaction abort.
> > +
> > +$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/a | _filter_scratch
> > +$BTRFS_UTIL_PROG subvolume create $SCRATCH_MNT/a/b | _filter_scratch
> > +$BTRFS_UTIL_PROG subvolume snapshot $SCRATCH_MNT/a $SCRATCH_MNT/c \
> > +	| _filter_scratch
> > +ls $SCRATCH_MNT/c/b
>
> Isn't this ls redundant?

No we need the dummy entry in cache before we add the root ref during the 
rename.  Thanks,

Josef