From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Benjamin Marzinski <bmarzins@redhat.com>
Date: Wed, 14 Oct 2020 18:38:20 -0500
Subject: [PATCH] libmultipath: add eh_deadline multipath.conf parameter

There are times a fc rport is never lost, meaning that fast_io_fail_tmo
and dev_loss_tmo never trigger, but scsi commands still hang. This can
cause problems in cases where users have string timing requirements, and
the easiest way to solve these issues is to set eh_deadline. Since it's
already possible to set fast_io_fail_tmo and dev_loss_tmo from
multipath.conf, and have multipath take care of setting it correctly for
the scsi devices in sysfs, it makes sense to allow users to set
eh_deadline here as well.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/config.c      |  2 ++
 libmultipath/config.h      |  2 ++
 libmultipath/configure.c   |  1 +
 libmultipath/dict.c        | 10 +++++++
 libmultipath/discovery.c   | 58 +++++++++++++++++++++++++++++++++-----
 libmultipath/propsel.c     | 17 +++++++++++
 libmultipath/propsel.h     |  1 +
 libmultipath/structs.h     |  7 +++++
 multipath/multipath.conf.5 | 16 +++++++++++
 9 files changed, 107 insertions(+), 7 deletions(-)

diff --git a/libmultipath/config.c b/libmultipath/config.c
index 26f8e050..a71db2d0 100644
--- a/libmultipath/config.c
+++ b/libmultipath/config.c
@@ -359,6 +359,7 @@ merge_hwe (struct hwentry * dst, struct hwentry * src)
 	merge_num(flush_on_last_del);
 	merge_num(fast_io_fail);
 	merge_num(dev_loss);
+	merge_num(eh_deadline);
 	merge_num(user_friendly_names);
 	merge_num(retain_hwhandler);
 	merge_num(detect_prio);
@@ -514,6 +515,7 @@ store_hwe (vector hwtable, struct hwentry * dhwe)
 	hwe->flush_on_last_del = dhwe->flush_on_last_del;
 	hwe->fast_io_fail = dhwe->fast_io_fail;
 	hwe->dev_loss = dhwe->dev_loss;
+	hwe->eh_deadline = dhwe->eh_deadline;
 	hwe->user_friendly_names = dhwe->user_friendly_names;
 	hwe->retain_hwhandler = dhwe->retain_hwhandler;
 	hwe->detect_prio = dhwe->detect_prio;
diff --git a/libmultipath/config.h b/libmultipath/config.h
index f38c7639..a22c1b4e 100644
--- a/libmultipath/config.h
+++ b/libmultipath/config.h
@@ -64,6 +64,7 @@ struct hwentry {
 	int flush_on_last_del;
 	int fast_io_fail;
 	unsigned int dev_loss;
+	int eh_deadline;
 	int user_friendly_names;
 	int retain_hwhandler;
 	int detect_prio;
@@ -149,6 +150,7 @@ struct config {
 	int attribute_flags;
 	int fast_io_fail;
 	unsigned int dev_loss;
+	int eh_deadline;
 	int log_checker_err;
 	int allow_queueing;
 	int find_multipaths;
diff --git a/libmultipath/configure.c b/libmultipath/configure.c
index 96c79610..b7113291 100644
--- a/libmultipath/configure.c
+++ b/libmultipath/configure.c
@@ -340,6 +340,7 @@ int setup_map(struct multipath *mpp, char *params, int params_size,
 	select_gid(conf, mpp);
 	select_fast_io_fail(conf, mpp);
 	select_dev_loss(conf, mpp);
+	select_eh_deadline(conf, mpp);
 	select_reservation_key(conf, mpp);
 	select_deferred_remove(conf, mpp);
 	select_marginal_path_err_sample_time(conf, mpp);
diff --git a/libmultipath/dict.c b/libmultipath/dict.c
index ce8e1cda..8fd91d8c 100644
--- a/libmultipath/dict.c
+++ b/libmultipath/dict.c
@@ -911,6 +911,13 @@ declare_ovr_snprint(dev_loss, print_dev_loss)
 declare_hw_handler(dev_loss, set_dev_loss)
 declare_hw_snprint(dev_loss, print_dev_loss)
 
+declare_def_handler(eh_deadline, set_undef_off_zero)
+declare_def_snprint(eh_deadline, print_undef_off_zero)
+declare_ovr_handler(eh_deadline, set_undef_off_zero)
+declare_ovr_snprint(eh_deadline, print_undef_off_zero)
+declare_hw_handler(eh_deadline, set_undef_off_zero)
+declare_hw_snprint(eh_deadline, print_undef_off_zero)
+
 static int
 set_pgpolicy(vector strvec, void *ptr)
 {
@@ -1776,6 +1783,7 @@ init_keywords(vector keywords)
 	install_keyword("gid", &def_gid_handler, &snprint_def_gid);
 	install_keyword("fast_io_fail_tmo", &def_fast_io_fail_handler, &snprint_def_fast_io_fail);
 	install_keyword("dev_loss_tmo", &def_dev_loss_handler, &snprint_def_dev_loss);
+	install_keyword("eh_deadline", &def_eh_deadline_handler, &snprint_def_eh_deadline);
 	install_keyword("bindings_file", &def_bindings_file_handler, &snprint_def_bindings_file);
 	install_keyword("wwids_file", &def_wwids_file_handler, &snprint_def_wwids_file);
 	install_keyword("prkeys_file", &def_prkeys_file_handler, &snprint_def_prkeys_file);
@@ -1885,6 +1893,7 @@ init_keywords(vector keywords)
 	install_keyword("flush_on_last_del", &hw_flush_on_last_del_handler, &snprint_hw_flush_on_last_del);
 	install_keyword("fast_io_fail_tmo", &hw_fast_io_fail_handler, &snprint_hw_fast_io_fail);
 	install_keyword("dev_loss_tmo", &hw_dev_loss_handler, &snprint_hw_dev_loss);
+	install_keyword("eh_deadline", &hw_eh_deadline_handler, &snprint_hw_eh_deadline);
 	install_keyword("user_friendly_names", &hw_user_friendly_names_handler, &snprint_hw_user_friendly_names);
 	install_keyword("retain_attached_hw_handler", &hw_retain_hwhandler_handler, &snprint_hw_retain_hwhandler);
 	install_keyword("detect_prio", &hw_detect_prio_handler, &snprint_hw_detect_prio);
@@ -1925,6 +1934,7 @@ init_keywords(vector keywords)
 	install_keyword("flush_on_last_del", &ovr_flush_on_last_del_handler, &snprint_ovr_flush_on_last_del);
 	install_keyword("fast_io_fail_tmo", &ovr_fast_io_fail_handler, &snprint_ovr_fast_io_fail);
 	install_keyword("dev_loss_tmo", &ovr_dev_loss_handler, &snprint_ovr_dev_loss);
+	install_keyword("eh_deadline", &ovr_eh_deadline_handler, &snprint_ovr_eh_deadline);
 	install_keyword("user_friendly_names", &ovr_user_friendly_names_handler, &snprint_ovr_user_friendly_names);
 	install_keyword("retain_attached_hw_handler", &ovr_retain_hwhandler_handler, &snprint_ovr_retain_hwhandler);
 	install_keyword("detect_prio", &ovr_detect_prio_handler, &snprint_ovr_detect_prio);
diff --git a/libmultipath/discovery.c b/libmultipath/discovery.c
index 01aadba9..a328aafa 100644
--- a/libmultipath/discovery.c
+++ b/libmultipath/discovery.c
@@ -577,6 +577,42 @@ sysfs_get_asymmetric_access_state(struct path *pp, char *buff, int buflen)
 	return !!preferred;
 }
 
+static int
+sysfs_set_eh_deadline(struct multipath *mpp, struct path *pp)
+{
+	struct udev_device *hostdev;
+	char host_name[HOST_NAME_LEN], value[16];
+	int ret;
+
+	if (mpp->eh_deadline == EH_DEADLINE_UNSET)
+		return 0;
+
+	sprintf(host_name, "host%d", pp->sg_id.host_no);
+	hostdev = udev_device_new_from_subsystem_sysname(udev,
+			"scsi_host", host_name);
+	if (!hostdev)
+		return 1;
+
+	if (mpp->eh_deadline == EH_DEADLINE_OFF)
+		sprintf(value, "off");
+	else if (mpp->eh_deadline == EH_DEADLINE_ZERO)
+		sprintf(value, "0");
+	else
+		snprintf(value, 16, "%u", mpp->eh_deadline);
+
+	ret = sysfs_attr_set_value(hostdev, "eh_deadline",
+				   value, strlen(value));
+	/*
+	 * not all scsi drivers support setting eh_deadline, so failing
+	 * is totally reasonable
+	 */
+	if (ret <= 0)
+		condlog(4, "%s: failed to set eh_deadline to %s, error %d", udev_device_get_sysname(hostdev), value, -ret);
+
+	udev_device_unref(hostdev);
+	return (ret <= 0);
+}
+
 static void
 sysfs_set_rport_tmo(struct multipath *mpp, struct path *pp)
 {
@@ -787,16 +823,24 @@ sysfs_set_scsi_tmo (struct multipath *mpp, unsigned int checkint)
 			mpp->alias, mpp->fast_io_fail);
 		mpp->fast_io_fail = MP_FAST_IO_FAIL_OFF;
 	}
-	if (!mpp->dev_loss && mpp->fast_io_fail == MP_FAST_IO_FAIL_UNSET)
+	if (!mpp->dev_loss && mpp->fast_io_fail == MP_FAST_IO_FAIL_UNSET &&
+	    mpp->eh_deadline == EH_DEADLINE_UNSET)
 		return 0;
 
 	vector_foreach_slot(mpp->paths, pp, i) {
-		if (pp->sg_id.proto_id == SCSI_PROTOCOL_FCP)
-			sysfs_set_rport_tmo(mpp, pp);
-		if (pp->sg_id.proto_id == SCSI_PROTOCOL_ISCSI)
-			sysfs_set_session_tmo(mpp, pp);
-		if (pp->sg_id.proto_id == SCSI_PROTOCOL_SAS)
-			sysfs_set_nexus_loss_tmo(mpp, pp);
+		if (pp->bus != SYSFS_BUS_SCSI)
+			continue;
+
+		if (mpp->dev_loss ||
+		    mpp->fast_io_fail != MP_FAST_IO_FAIL_UNSET) {
+			if (pp->sg_id.proto_id == SCSI_PROTOCOL_FCP)
+				sysfs_set_rport_tmo(mpp, pp);
+			else if (pp->sg_id.proto_id == SCSI_PROTOCOL_ISCSI)
+				sysfs_set_session_tmo(mpp, pp);
+			else if (pp->sg_id.proto_id == SCSI_PROTOCOL_SAS)
+				sysfs_set_nexus_loss_tmo(mpp, pp);
+		}
+		sysfs_set_eh_deadline(mpp, pp);
 	}
 	return 0;
 }
diff --git a/libmultipath/propsel.c b/libmultipath/propsel.c
index 725db2b1..1150cfe8 100644
--- a/libmultipath/propsel.c
+++ b/libmultipath/propsel.c
@@ -776,6 +776,23 @@ out:
 	return 0;
 }
 
+int select_eh_deadline(struct config *conf, struct multipath *mp)
+{
+	const char *origin;
+	char buff[12];
+
+	mp_set_ovr(eh_deadline);
+	mp_set_hwe(eh_deadline);
+	mp_set_conf(eh_deadline);
+	mp->eh_deadline = EH_DEADLINE_UNSET;
+	/* not changing sysfs in default cause, so don't print anything */
+	return 0;
+out:
+	print_undef_off_zero(buff, 12, mp->eh_deadline);
+	condlog(3, "%s: eh_deadline = %s %s", mp->alias, buff, origin);
+	return 0;
+}
+
 int select_flush_on_last_del(struct config *conf, struct multipath *mp)
 {
 	const char *origin;
diff --git a/libmultipath/propsel.h b/libmultipath/propsel.h
index 3d6edd8a..a68bacf0 100644
--- a/libmultipath/propsel.h
+++ b/libmultipath/propsel.h
@@ -17,6 +17,7 @@ int select_uid(struct config *conf, struct multipath *mp);
 int select_gid(struct config *conf, struct multipath *mp);
 int select_fast_io_fail(struct config *conf, struct multipath *mp);
 int select_dev_loss(struct config *conf, struct multipath *mp);
+int select_eh_deadline(struct config *conf, struct multipath *mp);
 int select_reservation_key(struct config *conf, struct multipath *mp);
 int select_retain_hwhandler (struct config *conf, struct multipath * mp);
 int select_detect_prio(struct config *conf, struct path * pp);
diff --git a/libmultipath/structs.h b/libmultipath/structs.h
index 29209984..65542dea 100644
--- a/libmultipath/structs.h
+++ b/libmultipath/structs.h
@@ -246,6 +246,12 @@ enum fast_io_fail_states {
 	MP_FAST_IO_FAIL_ZERO = UOZ_ZERO,
 };
 
+enum eh_deadline_states {
+	EH_DEADLINE_UNSET = UOZ_UNDEF,
+	EH_DEADLINE_OFF = UOZ_OFF,
+	EH_DEADLINE_ZERO = UOZ_ZERO,
+};
+
 struct vpd_vendor_page {
 	int pg;
 	const char *name;
@@ -366,6 +372,7 @@ struct multipath {
 	int ghost_delay;
 	int ghost_delay_tick;
 	unsigned int dev_loss;
+	int eh_deadline;
 	uid_t uid;
 	gid_t gid;
 	mode_t mode;
diff --git a/multipath/multipath.conf.5 b/multipath/multipath.conf.5
index 6dc26f10..60954574 100644
--- a/multipath/multipath.conf.5
+++ b/multipath/multipath.conf.5
@@ -700,6 +700,22 @@ The default is: \fB600\fR
 .
 .
 .TP
+.B eh_deadline
+Specify the maximum number of seconds the SCSI layer will spend doing error
+handling when scsi devices fail. After this timeout the scsi layer will perform
+a full HBA reset. Setting this may be necessary in cases where the rport is
+never lost, so \fIfast_io_fail_tmo\fR and \fIdev_loss_tmo\fR will never
+trigger, but (frequently do to load) scsi commands still hang. \fBNote:\fR when
+the scsi error handler performs the HBA reset, all target paths on that HBA
+will be affected. eh_deadline should only be set in cases where all targets on
+the affected HBAs are multipathed.
+.RS
+.TP
+The default is: \fB<unset>\fR
+.RE
+.
+.
+.TP
 .B bindings_file
 The full pathname of the binding file to be used when the user_friendly_names
 option is set.
-- 
2.17.2