On Fri, Dec 11, 2020 at 04:45:08PM +0800, Zorro Lang wrote: > On Thu, Dec 10, 2020 at 11:14:26AM -0500, Brian Foster wrote: > > cgroup writeback accounting does not track partition level > > statistics. Instead, I/O is accounted against the parent device. As > > a result, the test fails if the scratch device happens to be a > > device partition. Since parent level stats are potentially polluted > > by factors external to the test, wrap the scratch device in a > > loopback device to guarantee the test always runs on a top-level > > block device. > > > > Reported-by: Boyang Xue <bxue@xxxxxxxxxx> > > Signed-off-by: Brian Foster <bfoster@xxxxxxxxxx> > > --- > > tests/generic/563 | 21 ++++++++++++++------- > > 1 file changed, 14 insertions(+), 7 deletions(-) > > > > diff --git a/tests/generic/563 b/tests/generic/563 > > index 51deaa2f..9292dece 100755 > > --- a/tests/generic/563 > > +++ b/tests/generic/563 > > @@ -2,7 +2,7 @@ > > # SPDX-License-Identifier: GPL-2.0 > > # Copyright (c) 2019 Red Hat, Inc. All Rights Reserved. > > # > > -# FS QA Test No. 011 > > +# FS QA Test No. 563 > > # > > # This test verifies that cgroup aware writeback properly accounts I/Os in > > # various scenarios. We perform reads/writes from different combinations of > > @@ -26,6 +26,8 @@ _cleanup() > > > > echo $$ > $cgdir/cgroup.procs > > rmdir $cgdir/$seq-cg* > /dev/null 2>&1 > > + umount $SCRATCH_MNT > /dev/null 2>&1 > > + _destroy_loop_device $LOOP_DEV > /dev/null 2>&1 > > } > > > > # get standard environment, filters and checks > > @@ -42,14 +44,12 @@ rm -f $seqres.full > > _supported_fs generic > > _require_scratch > > _require_cgroup2 io > > +_require_loop > > > > # cgroup v2 writeback is only support on block devices so far > > _require_block_device $SCRATCH_DEV > > > > -smajor=$((0x`stat -L -c %t $SCRATCH_DEV`)) > > -sminor=$((0x`stat -L -c %T $SCRATCH_DEV`)) > > cgdir=$CGROUP2_PATH > > - > > iosize=$((1024 * 1024 * 8)) > > > > # Check cgroup read/write charges against expected values. Allow for some > > @@ -89,12 +89,19 @@ reset() > > rmdir $cgdir/$seq-cg* > /dev/null 2>&1 > > $XFS_IO_PROG -fc "pwrite 0 $iosize" $SCRATCH_MNT/file \ > > >> $seqres.full 2>&1 > > - _scratch_cycle_mount || _fail "mount failed" > > + umount $SCRATCH_MNT || _fail "umount failed" > > + _mount $LOOP_DEV $SCRATCH_MNT || _fail "mount failed" > > stat $SCRATCH_MNT/file > /dev/null > > } > > > > -_scratch_mkfs >> $seqres.full 2>&1 > > -_scratch_mount > > +# cgroup I/O accounting doesn't work on partitions. Use a loop device to rule > > +# that out. > > +LOOP_DEV=$(_create_loop_device $SCRATCH_DEV) > > I recommend using a file to create loop device. If you'd like to use SCRATCH_DEV > to create loop device directly, you'd better to change the "_require_scratch" > to "_require_scratch_nocheck". Or I think it might be failed, e.g. if SCRATCH_DEV > is a 4k sector size device. > What's the error that occurs with a 4k device, out of curiosity? I suppose if it's just a repair thing then using _nocheck probably makes sense (or technically might make sense regardless since we're not formatting the scratch device directly). I don't mind creating a file and using loop on that, but would like to make sure I understand if/why it's necessary. > Others look good to me. > Thanks for the feedback. Brian > Thanks, > Zorro > > > +smajor=$((0x`stat -L -c %t $LOOP_DEV`)) > > +sminor=$((0x`stat -L -c %T $LOOP_DEV`)) > > + > > +_mkfs_dev $LOOP_DEV >> $seqres.full 2>&1 > > +_mount $LOOP_DEV $SCRATCH_MNT || _fail "mount failed" > > > > echo "+io" > $cgdir/cgroup.subtree_control || _fail "subtree control" > > > > -- > > 2.26.2 > > >
