Re: [PATCH 4/4] generic: check for reasonable inode creation time

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Sun, Feb 03, 2019 at 05:14:55PM +0800, Eryu Guan wrote:
> On Tue, Jan 29, 2019 at 08:17:31AM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > If statx returns inode creation time (aka btime), check it to make sure
> > that the filesystem is setting a creation time that's reasonably close
> > to when it creates a file.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  tests/generic/709     |   61 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/709.out |    2 ++
> >  tests/generic/group   |    1 +
> >  3 files changed, 64 insertions(+)
> >  create mode 100755 tests/generic/709
> >  create mode 100644 tests/generic/709.out
> > 
> > 
> > diff --git a/tests/generic/709 b/tests/generic/709
> > new file mode 100755
> > index 00000000..724a16a8
> > --- /dev/null
> > +++ b/tests/generic/709
> > @@ -0,0 +1,61 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0+
> > +# Copyright (c) 2019 Oracle, Inc.  All Rights Reserved.
> > +#
> > +# FS QA Test No. 709
> > +#
> > +# Check that statx btime (aka creation time) is plausibly close to when
> > +# we created a file.  A bug caught during code review of xfs patches revealed
> > +# that there weren't any sanity checks of the btime values.
> > +#
> > +seq=`basename $0`
> > +seqres=$RESULT_DIR/$seq
> > +echo "QA output created by $seq"
> > +tmp=/tmp/$$
> > +status=1	# failure is the default!
> > +testfile=$TEST_DIR/$seq.txt
> > +trap "_cleanup; exit \$status" 0 1 2 3 15
> > +
> > +_cleanup()
> > +{
> > +	cd /
> > +	rm -f $tmp.* $testfile
> > +}
> > +
> > +# get standard environment, filters and checks
> > +. ./common/rc
> > +. ./common/attr
> > +. ./common/filter
> > +
> > +# real QA test starts here
> > +_supported_fs generic
> > +_supported_os Linux
> > +_require_xfs_io_command "statx" "-r"
> 
> testfile is in $TEST_DIR, needs _require_test here.
> 
> > +
> > +rm -f $seqres.full
> > +rm -f $testfile
> > +
> > +# Create a file and the time we created it
> > +now=$(date +%s)
> > +touch $testfile
> > +
> > +# Does statx return results with the BTIME flag set in the result mask?
> > +STATX_BTIME=0x800
> > +$XFS_IO_PROG -c "statx -F -r -m $STATX_BTIME" $testfile > $tmp.statx
> > +cat $tmp.statx >> $seqres.full
> > +
> > +result_mask=$(grep 'stat.mask =' $tmp.statx | cut -d ' ' -f 3)
> > +test -n "$result_mask" || _notrun "did not see stat.mask in output"
> > +
> > +test "$(( result_mask & STATX_BTIME ))" -ne 0 || \
> > +	_notrun "statx did not return btime"
> 
> We have a _require_btime helper now, I think that's sufficient.

It almost is, except that filesystems aren't required to report btime
unless the caller passes in STATX_BTIME.  ext4 will report btime whenever
it's available, but XFS does not fill in extra information that wasn't
asked of it.

I think this is a fairly simple patch to _require_btime, so I'll fix it
up in v2 and change the test to use it instead of all this opencoded
detection stuff.

> > +
> > +# Make sure the reported btime is within 5 seconds of the time we recorded
> > +# just prior to creating the file.
> > +btime=$(grep 'stat.btime.tv_sec =' $tmp.statx | cut -d ' ' -f 3)
> 
> And the btime timestamp could be retrieved like
> 
> btime=$(date +%s -d "$($XFS_IO_PROG -c "statx -v" $testfile | grep btime | cut -d= -f2)"
> 
> so we don't have to check the statx masks?

Yes.

--D

> Thanks,
> Eryu
> 
> > +test -n "$btime" || echo "error: did not see btime in output??"
> > +
> > +_within_tolerance "btime" "$btime" "$now" 0 5 -v
> > +
> > +status=0
> > +exit
> > diff --git a/tests/generic/709.out b/tests/generic/709.out
> > new file mode 100644
> > index 00000000..d8495ace
> > --- /dev/null
> > +++ b/tests/generic/709.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 709
> > +btime is in range
> > diff --git a/tests/generic/group b/tests/generic/group
> > index 6f5f28d8..9ce608c0 100644
> > --- a/tests/generic/group
> > +++ b/tests/generic/group
> > @@ -527,3 +527,4 @@
> >  522 soak long_rw
> >  523 auto quick attr
> >  524 auto quick
> > +709 auto quick
> >