Re: [PATCH 5/8] reflink: test unlinking a huge extent with a lot of refcount adjustments

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

On Thu, Jun 29, 2017 at 05:36:14PM +0800, Eryu Guan wrote:
> On Wed, Jun 21, 2017 at 02:57:48PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Test a regression in XFS where we blow out a transaction reservation if
> > we create a big file, share every other block, and delete the first
> > file.  There's nothing particularly fs-specific about this stress test,
> > so put it in generic.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> 
> This test took me 3019s to finish with v4.12-rc7 kernel, and another
> host "hung" at "Delete file1" (it had been more than 1 hour, and I lost
> my patience and hard-reboot the host). Are they expected results?

No.  The take-forever-or-crash behavior should be fixed by "xfs: try to
avoid blowing out the transaction reservation when bunmaping a shared
extent" in 4.13.  Feel free to hang on to this one until -rc1. :)

> If the bug is still existed in latest upstream kernel, I tend to merge
> it after the fix landing in linus tree. If v4.12-rc7 doesn't suffer from
> this bug, the test time should be reduced.

<shrug> This is what I saw just now:

FSTYP         -- xfs (debug)
PLATFORM      -- Linux/x86_64 birch-mtr0 4.12.0-rc6-dgc
MKFS_OPTIONS  -- -f -m reflink=1,rmapbt=1, -i sparse=1, /dev/pmem1
MOUNT_OPTIONS -- /dev/pmem1 /opt

generic/931      21s
Ran: generic/931
Passed all 1 tests

Though if it takes forever for everyone else, please kick this one out
of auto/quick.  At least in theory, before the patch the test will
either blow out a transaction reservation and hang the system, or if it
does succeed it'll have done so by scraping long and hard for log space.
That is probably why it takes 3000+ seconds on your test box, unless
you were also testing xfs for-next.

> And another minor nit below.
> 
> > ---
> >  tests/generic/931     |   94 +++++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/generic/931.out |    6 +++
> >  tests/generic/group   |    1 +
> >  3 files changed, 101 insertions(+)
> >  create mode 100755 tests/generic/931
> >  create mode 100644 tests/generic/931.out
> > 
> > 
> > diff --git a/tests/generic/931 b/tests/generic/931
> > new file mode 100755
> > index 0000000..afadf81
> > --- /dev/null
> > +++ b/tests/generic/931
> > @@ -0,0 +1,94 @@
> > +#! /bin/bash
> > +# FS QA Test No. 931
> > +#
> > +# See how well we handle deleting a file with a million refcount extents.
> > +#
> > +#-----------------------------------------------------------------------
> > +# Copyright (c) 2017, Oracle and/or its affiliates.  All Rights Reserved.
> > +#
> > +# This program is free software; you can redistribute it and/or
> > +# modify it under the terms of the GNU General Public License as
> > +# published by the Free Software Foundation.
> > +#
> > +# This program is distributed in the hope that it would be useful,
> > +# but WITHOUT ANY WARRANTY; without even the implied warranty of
> > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > +# GNU General Public License for more details.
> > +#
> > +# You should have received a copy of the GNU General Public License
> > +# along with this program; if not, write the Free Software Foundation,
> > +# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> > +#-----------------------------------------------------------------------
> > +
> > +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 -rf "$tmp".* $testdir/file1
> 
> 'rm -rf' looks a bit scary, and we're only deleting regular files not
> directories, 'rm -f' should be sufficient.

Yes.  Will you fix it on the way in or should I resend?

--D

> Thanks,
> Eryu
> 
> > +}
> > +
> > +# get standard environment, filters and checks
> > +. ./common/rc
> > +. ./common/filter
> > +. ./common/attr
> > +. ./common/reflink
> > +
> > +# real QA test starts here
> > +_supported_os Linux
> > +_require_scratch_reflink
> > +_require_cp_reflink
> > +_require_test_program "punch-alternating"
> > +
> > +rm -f "$seqres.full"
> > +
> > +echo "Format and mount"
> > +_scratch_mkfs > "$seqres.full" 2>&1
> > +_scratch_mount >> "$seqres.full" 2>&1
> > +
> > +testdir="$SCRATCH_MNT/test-$seq"
> > +mkdir "$testdir"
> > +
> > +# Setup for one million blocks, but we'll accept stress testing down to
> > +# 2^17 blocks... that should be plenty for anyone.
> > +fnr=20
> > +free_blocks=$(stat -f -c '%a' "$testdir")
> > +blksz=$(_get_block_size "$testdir")
> > +space_avail=$((free_blocks * blksz))
> > +calc_space() {
> > +	blocks_needed=$(( 2 ** (fnr + 1) ))
> > +	space_needed=$((blocks_needed * blksz * 5 / 4))
> > +}
> > +calc_space
> > +while test $space_needed -gt $space_avail; do
> > +	fnr=$((fnr - 1))
> > +	calc_space
> > +done
> > +test $fnr -lt 17 && _notrun "Insufficient space for stress test; would only create $blocks_needed extents ($space_needed/$space_avail blocks)."
> > +
> > +echo "Create a many-block file"
> > +echo "creating $blocks_needed blocks..." >> "$seqres.full"
> > +$XFS_IO_PROG -f -c "pwrite -S 0x61 -b 4194304 0 $((2 ** (fnr + 1) * blksz))" "$testdir/file1" >> "$seqres.full"
> > +
> > +echo "Reflinking file"
> > +_cp_reflink $testdir/file1 $testdir/file2
> > +
> > +echo "Punch file2"
> > +echo "Punching file2..." >> "$seqres.full"
> > +"$here/src/punch-alternating" "$testdir/file2" >> "$seqres.full"
> > +echo "...done" >> "$seqres.full"
> > +_scratch_cycle_mount
> > +
> > +echo "Delete file1"
> > +rm -rf $testdir/file1
> > +
> > +# success, all done
> > +status=0
> > +exit
> > diff --git a/tests/generic/931.out b/tests/generic/931.out
> > new file mode 100644
> > index 0000000..c7b724e
> > --- /dev/null
> > +++ b/tests/generic/931.out
> > @@ -0,0 +1,6 @@
> > +QA output created by 931
> > +Format and mount
> > +Create a many-block file
> > +Reflinking file
> > +Punch file2
> > +Delete file1
> > diff --git a/tests/generic/group b/tests/generic/group
> > index ab1e9d3..b0d1844 100644
> > --- a/tests/generic/group
> > +++ b/tests/generic/group
> > @@ -443,3 +443,4 @@
> >  438 auto
> >  439 auto quick punch
> >  440 auto quick encrypt
> > +931 auto quick clone
> > 
> --
> To unsubscribe from this list: send the line "unsubscribe fstests" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html