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

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

On Sun, Aug 27, 2023 at 09:06:44PM +0800, Zorro Lang 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" >> $seqres.full
> > +_scratch_mkfs -d "agsize=${desired_agsize}b" | _filter_mkfs 2> $tmp.mkfs >> $seqres.full
> > +source $tmp.mkfs
> > +
> > +test "$desired_agsize" -eq "$agsize" || _notrun "wanted agsize=$desired_agsize, got $agsize"
> > +
> > +_scratch_mount
> > +$XFS_IO_PROG -c 'fsmap -n 1024 -v' $SCRATCH_MNT >> $tmp.big
> > +$XFS_IO_PROG -c 'fsmap -n 1 -v' $SCRATCH_MNT >> $tmp.small
> 
> This line reports:
> 
>   xfs_io: xfsctl(XFS_IOC_GETFSMAP) iflags=0x0 ["/mnt/xfstests/scratch"]: Invalid argument
> 
> when the test case fails. Is that normal?

Yes.  The attached bugfix should make that go away.

--D

> > +
> > +diff -Naurpw $tmp.big $tmp.small
> > +
> > +# success, all done
> > +echo Silence is golden
> > +status=0
> > +exit
> > diff --git a/tests/xfs/935.out b/tests/xfs/935.out
> > new file mode 100644
> > index 0000000000..1b5422d1e3
> > --- /dev/null
> > +++ b/tests/xfs/935.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 935
> > +Silence is golden
> > 
>