Ratelimit deadman zevents as with delay zevents

Just as delay zevents can flood the zevent pipe when a vdev becomes
unresponsive, so do the deadman zevents.

Ratelimit deadman zevents according to the same tunable as for delay
zevents.

Enable deadman tests on FreeBSD and add a test for deadman event
ratelimiting. 

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Ryan Moeller <ryan@iXsystems.com>
Closes openzfs#11786

include/sys/vdev_impl.h

@@ -441,10 +441,11 @@ struct vdev {
 	kmutex_t	vdev_probe_lock; /* protects vdev_probe_zio	*/
 
 	/*
-	 * We rate limit ZIO delay and ZIO checksum events, since they
+	 * We rate limit ZIO delay, deadman, and checksum events, since they
 	 * can flood ZED with tons of events when a drive is acting up.
 	 */
 	zfs_ratelimit_t vdev_delay_rl;
+	zfs_ratelimit_t vdev_deadman_rl;
 	zfs_ratelimit_t vdev_checksum_rl;
 };
 

man/man5/zfs-module-parameters.5

@@ -1620,7 +1620,8 @@ Default value: \fB64\fR.
 \fBzfs_slow_io_events_per_second\fR (int)
 .ad
 .RS 12n
-Rate limit delay zevents (which report slow I/Os) to this many per second.
+Rate limit delay and deadman zevents (which report slow I/Os) to this many per
+second.
 .sp
 Default value: 20
 .RE

module/zfs/vdev.c

@@ -543,6 +543,8 @@ vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
 	 */
 	zfs_ratelimit_init(&vd->vdev_delay_rl, &zfs_slow_io_events_per_second,
 	    1);
+	zfs_ratelimit_init(&vd->vdev_deadman_rl, &zfs_slow_io_events_per_second,
+	    1);
 	zfs_ratelimit_init(&vd->vdev_checksum_rl,
 	    &zfs_checksum_events_per_second, 1);
 
@@ -1033,6 +1035,7 @@ vdev_free(vdev_t *vd)
 	cv_destroy(&vd->vdev_rebuild_io_cv);
 
 	zfs_ratelimit_fini(&vd->vdev_delay_rl);
+	zfs_ratelimit_fini(&vd->vdev_deadman_rl);
 	zfs_ratelimit_fini(&vd->vdev_checksum_rl);
 
 	if (vd == spa->spa_root_vdev)

module/zfs/zfs_fm.c

@@ -357,8 +357,8 @@ zfs_zevent_post_cb(nvlist_t *nvl, nvlist_t *detector)
 }
 
 /*
- * We want to rate limit ZIO delay and checksum events so as to not
- * flood ZED when a disk is acting up.
+ * We want to rate limit ZIO delay, deadman, and checksum events so as to not
+ * flood zevent consumers when a disk is acting up.
  *
  * Returns 1 if we're ratelimiting, 0 if not.
  */
@@ -367,11 +367,13 @@ zfs_is_ratelimiting_event(const char *subclass, vdev_t *vd)
 {
 	int rc = 0;
 	/*
-	 * __ratelimit() returns 1 if we're *not* ratelimiting and 0 if we
+	 * zfs_ratelimit() returns 1 if we're *not* ratelimiting and 0 if we
 	 * are.  Invert it to get our return value.
 	 */
 	if (strcmp(subclass, FM_EREPORT_ZFS_DELAY) == 0) {
 		rc = !zfs_ratelimit(&vd->vdev_delay_rl);
+	} else if (strcmp(subclass, FM_EREPORT_ZFS_DEADMAN) == 0) {
+		rc = !zfs_ratelimit(&vd->vdev_deadman_rl);
 	} else if (strcmp(subclass, FM_EREPORT_ZFS_CHECKSUM) == 0) {
 		rc = !zfs_ratelimit(&vd->vdev_checksum_rl);
 	}

tests/runfiles/common.run

@@ -571,6 +571,12 @@ tags = ['functional', 'cp_files']
 tests = ['ctime_001_pos' ]
 tags = ['functional', 'ctime']
 
+[tests/functional/deadman]
+tests = ['deadman_ratelimit', 'deadman_sync', 'deadman_zio']
+pre =
+post =
+tags = ['functional', 'deadman']
+
 [tests/functional/delegate]
 tests = ['zfs_allow_001_pos', 'zfs_allow_002_pos', 'zfs_allow_003_pos',
     'zfs_allow_004_pos', 'zfs_allow_005_pos', 'zfs_allow_006_pos',

tests/runfiles/linux.run

@@ -85,12 +85,6 @@ tags = ['functional', 'cli_root', 'zpool_split']
 tests = ['compress_004_pos']
 tags = ['functional', 'compression']
 
-[tests/functional/deadman:Linux]
-tests = ['deadman_sync', 'deadman_zio']
-pre =
-post =
-tags = ['functional', 'deadman']
-
 [tests/functional/devices:Linux]
 tests = ['devices_001_pos', 'devices_002_neg', 'devices_003_pos']
 tags = ['functional', 'devices']

tests/zfs-tests/tests/functional/deadman/Makefile.am

@@ -1,5 +1,6 @@
 pkgdatadir = $(datadir)/@PACKAGE@/zfs-tests/tests/functional/deadman
 dist_pkgdata_SCRIPTS = \
+	deadman_ratelimit.ksh \
 	deadman_sync.ksh \
 	deadman_zio.ksh
 

tests/zfs-tests/tests/functional/deadman/deadman_ratelimit.ksh

@@ -0,0 +1,78 @@
+#!/bin/ksh -p
+#
+# CDDL HEADER START
+#
+# The contents of this file are subject to the terms of the
+# Common Development and Distribution License (the "License").
+# You may not use this file except in compliance with the License.
+#
+# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+# or http://www.opensolaris.org/os/licensing.
+# See the License for the specific language governing permissions
+# and limitations under the License.
+#
+# When distributing Covered Code, include this CDDL HEADER in each
+# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+# If applicable, add the following below this CDDL HEADER, with the
+# fields enclosed by brackets "[]" replaced with your own identifying
+# information: Portions Copyright [yyyy] [name of copyright owner]
+#
+# CDDL HEADER END
+#
+
+#
+# Portions Copyright 2021 iXsystems, Inc.
+#
+
+# DESCRIPTION:
+#	Verify spa deadman events are rate limited
+#
+# STRATEGY:
+#	1. Reduce the zfs_slow_io_events_per_second to 1.
+#	2. Reduce the zfs_deadman_ziotime_ms to 1ms.
+#	3. Write data to a pool and read it back.
+#	4. Verify deadman events have been produced at a reasonable rate.
+#
+
+. $STF_SUITE/include/libtest.shlib
+. $STF_SUITE/tests/functional/deadman/deadman.cfg
+
+verify_runnable "both"
+
+function cleanup
+{
+	zinject -c all
+	default_cleanup_noexit
+
+	set_tunable64 SLOW_IO_EVENTS_PER_SECOND $OLD_SLOW_IO_EVENTS
+	set_tunable64 DEADMAN_ZIOTIME_MS $ZIOTIME_DEFAULT
+}
+
+log_assert "Verify spa deadman events are rate limited"
+log_onexit cleanup
+
+OLD_SLOW_IO_EVENTS=$(get_tunable SLOW_IO_EVENTS_PER_SECOND)
+log_must set_tunable64 SLOW_IO_EVENTS_PER_SECOND 1
+log_must set_tunable64 DEADMAN_ZIOTIME_MS 1
+
+# Create a new pool in order to use the updated deadman settings.
+default_setup_noexit $DISK1
+log_must zpool events -c
+
+mntpnt=$(get_prop mountpoint $TESTPOOL/$TESTFS)
+log_must file_write -b 1048576 -c 8 -o create -d 0 -f $mntpnt/file
+log_must zpool export $TESTPOOL
+log_must zpool import $TESTPOOL
+log_must zinject -d $DISK1 -D 5:1 $TESTPOOL
+log_must dd if=$mntpnt/file of=$TEST_BASE_DIR/devnull oflag=sync
+
+events=$(zpool events $TESTPOOL | grep -c ereport.fs.zfs.deadman)
+log_note "events=$events"
+if [ "$events" -lt 1 ]; then
+	log_fail "Expect >= 1 deadman events, $events found"
+fi
+if [ "$events" -gt 10 ]; then
+	log_fail "Expect <= 10 deadman events, $events found"
+fi
+
+log_pass "Verify spa deadman events are rate limited"

tests/zfs-tests/tests/functional/deadman/deadman_sync.ksh

@@ -73,7 +73,11 @@ log_must zinject -c all
 log_must zpool sync
 
 # Log txg sync times for reference and the zpool event summary.
-log_must cat /proc/spl/kstat/zfs/$TESTPOOL/txgs
+if is_freebsd; then
+	log_must sysctl -n kstat.zfs.$TESTPOOL.txgs
+else
+	log_must cat /proc/spl/kstat/zfs/$TESTPOOL/txgs
+fi
 log_must zpool events
 
 # Verify at least 5 deadman events were logged.  The first after 5 seconds,