Re: [RFC PATCH] fstests: test fix for an agbno overflow in __xfs_getfsmap_datadev

[Dave Chinner <david@fromorbit.com>]

On Wed, Aug 23, 2023 at 08:19:39PM -0700, Darrick J. Wong wrote:
> On Thu, Aug 24, 2023 at 12:36:11PM +1000, Dave Chinner wrote:
> > On Tue, Aug 22, 2023 at 06:02:39PM -0700, Darrick J. Wong wrote:
> > > From: Darrick J. Wong <djwong@kernel.org>
> > > 
> > > Dave Chinner reported that xfs/273 fails if the AG size happens to be an
> > > exact power of two.  I traced this to an agbno integer overflow when the
> > > current GETFSMAP call is a continuation of a previous GETFSMAP call, and
> > > the last record returned was non-shareable space at the end of an AG.
> > > 
> > > This is the regression test for that bug.
> > > 
> > > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > > ---
> > >  tests/xfs/935     |   55 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> > >  tests/xfs/935.out |    2 ++
> > >  2 files changed, 57 insertions(+)
> > >  create mode 100755 tests/xfs/935
> > >  create mode 100644 tests/xfs/935.out
> > > 
> > > diff --git a/tests/xfs/935 b/tests/xfs/935
> > > new file mode 100755
> > > index 0000000000..a06f2fc8dc
> > > --- /dev/null
> > > +++ b/tests/xfs/935
> > > @@ -0,0 +1,55 @@
> > > +#! /bin/bash
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +# Copyright (c) 2023 Oracle.  All Rights Reserved.
> > > +#
> > > +# FS QA Test 935
> > > +#
> > > +# Regression test for an agbno overflow bug in XFS GETFSMAP involving an
> > > +# fsmap_advance call.  Userspace can indicate that a GETFSMAP call is actually
> > > +# a continuation of a previous call by setting the "low" key to the last record
> > > +# returned by the previous call.
> > > +#
> > > +# If the last record returned by GETFSMAP is a non-shareable extent at the end
> > > +# of an AG and the AG size is exactly a power of two, the startblock in the low
> > > +# key of the rmapbt query can be set to a value larger than EOAG.  When this
> > > +# happens, GETFSMAP will return EINVAL instead of returning records for the
> > > +# next AG.
> > > +#
> > > +. ./common/preamble
> > > +_begin_fstest auto quick fsmap
> > > +
> > > +. ./common/filter
> > > +
> > > +_fixed_by_git_commit kernel XXXXXXXXXXXXX \
> > > +	"xfs: fix an agbno overflow in __xfs_getfsmap_datadev"
> > > +
> > > +# Modify as appropriate.
> > > +_supported_fs generic
> > > +_require_xfs_io_command fsmap
> > > +_require_xfs_scratch_rmapbt
> > > +
> > > +_scratch_mkfs | _filter_mkfs 2> $tmp.mkfs >> $seqres.full
> > > +source $tmp.mkfs
> > > +
> > > +# Find the next power of two agsize smaller than whatever the default is.
> > > +for ((p = 31; p > 0; p--)); do
> > > +	desired_agsize=$((2 ** p))
> > > +	test "$desired_agsize" -lt "$agsize" && break
> > > +done
> > > +
> > > +echo "desired asize=$desired_agsize" >> $seqres.full
> >                  agsize
> 
> Fixed.
> 
> > Otherwise looks fine.
> > 
> > Reviewed-by: Dave Chinner <dchinner@redhat.com>
> 
> Does the kernel patch fix the bug on your end too?

Haven't had a chance to test it yet. I'll let you know when I do.

-Dave.
-- 
Dave Chinner
david@fromorbit.com