Hi, James, thanks for sending this in. Sorry for the delay, I've been out of the office for a couple of weeks. A few comments below. On Thu, Jun 08, 2017 at 08:28:12PM +0800, James Wang wrote: > Add a regression testing for loop device. when an unbound device > be close that take too long time. kernel will consume serveral orders > of magnitude more wall time than it does for a mounted device. > > Signed-off-by: James Wang <jnwang@xxxxxxxx> > --- > tests/loop/002 | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > tests/loop/002.out | 2 ++ > 2 files changed, 79 insertions(+) > > diff --git a/tests/loop/002 b/tests/loop/002 > new file mode 100755 > index 0000000..fd607d1 > --- /dev/null > +++ b/tests/loop/002 > @@ -0,0 +1,77 @@ > +#!/bin/bash > +# > +# Test if close()ing a unbound loop device is too slow > +# Copyright (C) 2017 James Wang > +# > +# 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, either version 3 of the License, or > +# (at your option) any later version. > +# > +# This program is distributed in the hope that it will 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, see <http://www.gnu.org/licenses/>. > + > +DESCRIPTION="Test if close()ing a unbound loop device is too slow" > + > +QUICK=1 > + > +function run_test() { For consistency with everything else in blktests, please don't use "function" when defining a function. > + TIMEFORMAT='%5R' > + time { > + for f in `ls /dev/loop[0-9]*|sort`; do dd if=$f of=/dev/null bs=512 count=1 >/dev/null 2>&1; done > + } > +} > +function clean_up() { > + if lsmod | grep loop >/dev/null 2>&1; then > + umount /dev/loop* >/dev/null 2>&1 > + losetup -D > + sleep 5 > + > + if ! rmmod loop;then > + return 2; > + fi > + fi > +} > + > +function prepare() { > + modprobe loop max_loop=64 If loop is already loaded, this won't work, right? > + dd if=/dev/zero of=${TMPDIR}/disk bs=512 count=200K >/dev/null 2>&1 > + for((i=0;i<4;i++)) > + do > + losetup -f ${TMPDIR}/disk; > + done > + mkfs.ext4 -F /dev/loop0 >/dev/null 2>&1 Hm, so if I happened to have something I care about on /dev/loop0, running blktests will destroy it? This is a no-go. > + for((i=0;i<4;i++)) > + do > + mkdir -p t$i; > + mount /dev/loop$i t$i; > + done > + > +} > + > + > +test() { > + echo "Running ${TEST_NAME}" > + > + prepare > + SECONDS=0 > + run_test >/dev/null 2>&1 > + DURATION=${SECONDS} Nifty, I didn't know about $SECONDS. > + > + clean_up > + if ! clean_up; then > + echo "Test complete" > + return 2 > + fi > + echo "Test complete" > + if [[ "${DURATION}" -gt 1 ]]; then > + return 1 > + else > + return 0 > + fi I'd really like a meaningful output if this test fails, so something like this instead of the if/else if [[ "${DURATION}" -gt 1 ]]; then echo "test took too long ($DURATION seconds)" fi > +} > diff --git a/tests/loop/002.out b/tests/loop/002.out > new file mode 100644 > index 0000000..5c34a37 > --- /dev/null > +++ b/tests/loop/002.out > @@ -0,0 +1,2 @@ > +Running loop/002 > +Test complete > -- > 2.12.3 > Overall, is there an easier way to test this than setting up 64 loop devices at modprobe time? E.g., can you losetup -f and run it on a single loop device many times to measure the same issue? Thanks again!
