linux-kernel - [PATCH blktests v2] loop/002: Regression testing for loop device flush

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Message-Id: <20170627040147.8823-1-jnwang@suse.com>
Date:   Tue, 27 Jun 2017 12:01:47 +0800
From:   James Wang <jnwang@...e.com>
To:     osandov@...com
Cc:     osandov@...ndov.com, hch@...radead.org, axboe@...com,
        hare@...e.com, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, mgorman@...e.com,
        James Wang <jnwang@...e.com>
Subject: [PATCH blktests v2] loop/002: Regression testing for loop device flush

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@...e.com>
---
 tests/loop/002     | 63 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/loop/002.out |  2 ++
 2 files changed, 65 insertions(+)
 create mode 100755 tests/loop/002
 create mode 100644 tests/loop/002.out

diff --git a/tests/loop/002 b/tests/loop/002
new file mode 100755
index 0000000..ef69729
--- /dev/null
+++ b/tests/loop/002
@@ -0,0 +1,63 @@
+#!/bin/bash
+#
+# Test if close()ing a unbound loop device is too slow
+# Copyright (C) 2017 James Wang <jnwang@...e.com>
+#
+# 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
+
+run_test() {
+	TIMEFORMAT='%5R'
+	time {
+		for ((i=0;i<200;i++)); do dd if=/dev/loop0 of=/dev/null  bs=512 count=1 >/dev/null 2>&1; done
+	}
+}
+clean_up() {
+	if lsmod | grep loop >/dev/null 2>&1; then
+		if ! rmmod loop;then
+			return 2;
+		fi
+	fi
+}
+
+prepare() {
+	modprobe loop max_loop=1
+}
+
+
+test() {
+	echo "Running ${TEST_NAME}"
+
+	clean_up
+	prepare
+	SECONDS=0
+	run_test >/dev/null 2>&1
+	DURATION=${SECONDS}
+
+	clean_up
+	if ! clean_up; then
+		echo "Test complete"
+		return 2
+	fi
+	echo "Test complete"
+	if [[ "${DURATION}" -gt 1 ]]; then
+		echo "test took too long ($URATION seconds)"
+		return 1
+	else
+		return 0
+	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