Re: [PATCH] generic: test truncating mixed written/unwritten XFS realtime extent

[Omar Sandoval <osandov@osandov.com>]

On Tue, Nov 26, 2019 at 05:26:46PM -0800, Darrick J. Wong wrote:
> On Tue, Nov 26, 2019 at 12:13:56PM -0800, Omar Sandoval wrote:
> > From: Omar Sandoval <osandov@fb.com>
> > 
> > The only XFS-specific part of this test is the setup, so we can make the
> > rest a generic test. It's slow, though, as it needs to write 8GB to
> > convert a big unwritten extent to written.
> > 
> > Signed-off-by: Omar Sandoval <osandov@fb.com>
> > ---
> >  tests/generic/586     | 59 +++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/586.out |  2 ++
> >  tests/generic/group   |  1 +
> >  3 files changed, 62 insertions(+)
> >  create mode 100755 tests/generic/586
> >  create mode 100644 tests/generic/586.out
> > 
> > diff --git a/tests/generic/586 b/tests/generic/586
> > new file mode 100755
> > index 00000000..5bcad68b
> > --- /dev/null
> > +++ b/tests/generic/586
> > @@ -0,0 +1,59 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2019 Facebook.  All Rights Reserved.
> > +#
> > +# FS QA Test 586
> > +#
> > +# Test "xfs: fix realtime file data space leak" and "xfs: don't check for AG
> > +# deadlock for realtime files in bunmapi". On XFS without the fix, rm will hang
> > +# forever. On other filesystems, this just tests writing into big fallocates.
> > +#
> > +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 $seqres.full
> > +
> > +_supported_fs generic
> > +_supported_os Linux
> > +_require_scratch
> > +
> > +maxextlen=$((0x1fffff))
> 
> /me wonders if we ought to move this to common/xfs and hoist the other
> place (xfs/507) where we define this.
> 
> > +bs=4096
> > +rextsize=4
> > +
> > +extra_options=""
> > +if [[ $FSTYP = xfs && $USE_EXTERNAL = yes && -n $SCRATCH_RTDEV ]]; then
> > +	extra_options="$extra_options -bsize=$bs"
> 
> Hm.  Could you rework this to _require_realtime, and if the caller
> didn't set SCRATCH_RTDEV, create a file on the test device so that we
> can always do the realtime test if the kernel supports it?  That will
> ensure that this gets more testing that it does now...

Sorry, I don't follow. _require_realtime checks that SCRATCH_RTDEV was
set. Did you mean something like this?

if [[ $USE_EXTERNAL = yes && -n $SCRATCH_RTDEV ]]; then
	use the configured rtdev
else
	_require_test
	_require_scratch
	set up a loop device on the test filesystem as the rtdev
fi

> > +	extra_options="$extra_options -r extsize=$((bs * rextsize))"
> > +	extra_options="$extra_options -d agsize=$(((maxextlen + 1) * bs / 2)),rtinherit=1"
> 
> ...particularly because I don't think very many people actually run
> fstests with rt enabled /and/ rtinherit set to stress the realtime
> allocator.
> 
> (I did a year ago and out came a torrent of bugs such that someone could
> probably write themselves a nice year end bonus just fixing all that,
> software is terrible :()
> 
> > +fi
> > +_scratch_mkfs $extra_options >>$seqres.full 2>&1
> > +_scratch_mount
> > +_require_fs_space "$SCRATCH_MNT" "$(((maxextlen + 1) * bs / 1024))"
> > +
> > +fallocate -l $(((maxextlen + 1 - rextsize) * bs)) "$SCRATCH_MNT/file"
> > +sync
> 
> $XFS_IO_PROG -c "falloc 0 <math expression>" -c fsync $SCRATCH_MNT/file

Will fix.

> (Hm ok, fallocate the first 2097148 blocks of the file...)

Oops, I'll add some explanations for all of this stuff.

Thanks for taking a look!

> > +fallocate -o $(((maxextlen + 1 - rextsize) * bs)) -l $((rextsize * bs)) "$SCRATCH_MNT/file"
> > +sync
> 
> $XFS_IO_PROG -c "falloc <the -o expression> <the -l expression>" -c fsync $SCRATCH_MNT/file
> 
> (now fallocate blocks 2097148 to 2097152)
> 
> (Not sure why you do the last rtext separately...)
> 
> > +dd if=/dev/zero of="$SCRATCH_MNT/file" bs=$bs count=$((maxextlen + 2 - rextsize)) conv=notrunc status=none
> > +sync
> 
> $XFS_IO_PROG -c "pwrite <count= expression> $bs" -c fsync $SCRATCH_MNT/file
> 
> (and finally write to block 2097149?)
> 
> --D