[PATCH 2/4] nvme-fc: marginal path handling

[hare@kernel.org]

From: Hannes Reinecke <hare@kernel.org>

FPIN LI (link integrity) messages are received when the attached
fabric detects hardware errors. In response to these messages I/O
should be directed away from the affected ports, and only used
if the 'optimized' paths are unavailable.
To handle this a new controller flag 'NVME_CTRL_MARGINAL' is added
which will cause the multipath scheduler to skip these paths when
checking for 'optimized' paths. They are, however, still eligible
for non-optimized path selected. The flag is cleared upon reset as then the
faulty hardware might be replaced.

Signed-off-by: Hannes Reinecke <hare@kernel.org>
---
 drivers/nvme/host/core.c       |  1 +
 drivers/nvme/host/fc.c         | 99 ++++++++++++++++++++++++++++++++++
 drivers/nvme/host/multipath.c  | 17 +++---
 drivers/nvme/host/nvme.h       |  6 +++
 include/linux/nvme-fc-driver.h |  3 ++
 5 files changed, 120 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index eb6ea8acb3cc..ab851df98079 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -4833,6 +4833,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 	WRITE_ONCE(ctrl->state, NVME_CTRL_NEW);
 	ctrl->passthru_err_log_enabled = false;
 	clear_bit(NVME_CTRL_FAILFAST_EXPIRED, &ctrl->flags);
+	clear_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
 	spin_lock_init(&ctrl->lock);
 	mutex_init(&ctrl->namespaces_lock);
 
diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index 2257c3c96dd2..475a636d1f7d 100644
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -786,6 +786,10 @@ nvme_fc_ctrl_connectivity_loss(struct nvme_fc_ctrl *ctrl)
 		"Reconnect", ctrl->cnum);
 
 	set_bit(ASSOC_FAILED, &ctrl->flags);
+
+	/* clear 'marginal' flag as controller will be reset */
+	clear_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
+
 	nvme_reset_ctrl(&ctrl->ctrl);
 }
 
@@ -3713,6 +3717,101 @@ static struct nvmf_transport_ops nvme_fc_transport = {
 	.create_ctrl	= nvme_fc_create_ctrl,
 };
 
+static struct nvme_fc_rport *nvme_fc_rport_from_wwpn(struct nvme_fc_lport *lport,
+		u64 rport_wwpn)
+{
+	struct nvme_fc_rport *rport;
+
+	list_for_each_entry(rport, &lport->endp_list, endp_list) {
+		if (!nvme_fc_rport_get(rport))
+			continue;
+		if (rport->remoteport.port_name == rport_wwpn &&
+		    rport->remoteport.port_role & FC_PORT_ROLE_NVME_TARGET)
+			return rport;
+		nvme_fc_rport_put(rport);
+	}
+	return NULL;
+}
+
+static void
+nvme_fc_fpin_li_lport_update(struct nvme_fc_lport *lport, struct fc_fn_li_desc *li)
+{
+	unsigned int i, pname_count = be32_to_cpu(li->pname_count);
+	u64 attached_wwpn = be64_to_cpu(li->attached_wwpn);
+	struct nvme_fc_rport *attached_rport;
+
+	for (i = 0; i < pname_count; i++) {
+		struct nvme_fc_rport *rport;
+		u64 wwpn = be64_to_cpu(li->pname_list[i]);
+
+		rport = nvme_fc_rport_from_wwpn(lport, wwpn);
+		if (!rport)
+			continue;
+		if (wwpn != attached_wwpn) {
+			struct nvme_fc_ctrl *ctrl;
+
+			spin_lock_irq(&rport->lock);
+			list_for_each_entry(ctrl, &rport->ctrl_list, ctrl_list)
+				set_bit(NVME_CTRL_MARGINAL, &ctrl->ctrl.flags);
+			spin_unlock_irq(&rport->lock);
+		}
+		nvme_fc_rport_put(rport);
+	}
+
+	attached_rport = nvme_fc_rport_from_wwpn(lport, attached_wwpn);
+	if (attached_rport) {
+		struct nvme_fc_ctrl *ctrl;
+
+		spin_lock_irq(&attached_rport->lock);
+		list_for_each_entry(ctrl, &attached_rport->ctrl_list, ctrl_list)
+			set_bit(NVME_CTRL_MARGINAL, &ctrl->ctrl.flags);
+		spin_unlock_irq(&attached_rport->lock);
+		nvme_fc_rport_put(attached_rport);
+	}
+}
+
+/**
+ * fc_host_fpin_rcv() - Process a received FPIN.
+ * @localport:		local port the FPIN was received on
+ * @fpin_len:		length of FPIN payload, in bytes
+ * @fpin_buf:		pointer to FPIN payload
+ * Notes:
+ *	This routine assumes no locks are held on entry.
+ */
+void
+nvme_fc_fpin_rcv(struct nvme_fc_local_port *localport,
+		 u32 fpin_len, char *fpin_buf)
+{
+	struct nvme_fc_lport *lport;
+	struct fc_els_fpin *fpin = (struct fc_els_fpin *)fpin_buf;
+	union fc_tlv_desc *tlv;
+	u32 bytes_remain;
+	u32 dtag;
+
+	if (!localport)
+		return;
+	lport = localport_to_lport(localport);
+	tlv = &fpin->fpin_desc[0];
+	bytes_remain = fpin_len - offsetof(struct fc_els_fpin, fpin_desc);
+	bytes_remain = min_t(u32, bytes_remain, be32_to_cpu(fpin->desc_len));
+
+	while (bytes_remain >= FC_TLV_DESC_HDR_SZ &&
+	       bytes_remain >= FC_TLV_DESC_SZ_FROM_LENGTH(tlv)) {
+		dtag = be32_to_cpu(tlv->hdr.desc_tag);
+		switch (dtag) {
+		case ELS_DTAG_LNK_INTEGRITY:
+			nvme_fc_fpin_li_lport_update(lport, &tlv->li);
+			break;
+		default:
+			break;
+		}
+
+		bytes_remain -= FC_TLV_DESC_SZ_FROM_LENGTH(tlv);
+		tlv = fc_tlv_next_desc(tlv);
+	}
+}
+EXPORT_SYMBOL(nvme_fc_fpin_rcv);
+
 /* Arbitrary successive failures max. With lots of subsystems could be high */
 #define DISCOVERY_MAX_FAIL	20
 
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index 250f3da67cc9..6d7425d34dfc 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -273,11 +273,14 @@ static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
 
 		switch (ns->ana_state) {
 		case NVME_ANA_OPTIMIZED:
-			if (distance < found_distance) {
-				found_distance = distance;
-				found = ns;
+			if (!nvme_ctrl_is_marginal(ns->ctrl)) {
+				if (distance < found_distance) {
+					found_distance = distance;
+					found = ns;
+				}
+				break;
 			}
-			break;
+			fallthrough;
 		case NVME_ANA_NONOPTIMIZED:
 			if (distance < fallback_distance) {
 				fallback_distance = distance;
@@ -330,7 +333,8 @@ static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head)
 
 		if (ns->ana_state == NVME_ANA_OPTIMIZED) {
 			found = ns;
-			goto out;
+			if (!nvme_ctrl_is_marginal(ns->ctrl))
+				goto out;
 		}
 		if (ns->ana_state == NVME_ANA_NONOPTIMIZED)
 			found = ns;
@@ -394,7 +398,8 @@ static struct nvme_ns *nvme_queue_depth_path(struct nvme_ns_head *head)
 static inline bool nvme_path_is_optimized(struct nvme_ns *ns)
 {
 	return nvme_ctrl_state(ns->ctrl) == NVME_CTRL_LIVE &&
-		ns->ana_state == NVME_ANA_OPTIMIZED;
+		ns->ana_state == NVME_ANA_OPTIMIZED &&
+		!nvme_ctrl_is_marginal(ns->ctrl);
 }
 
 static struct nvme_ns *nvme_numa_path(struct nvme_ns_head *head)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index c1b4ef6c5233..503df5dc2934 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -275,6 +275,7 @@ enum nvme_ctrl_flags {
 	NVME_CTRL_SKIP_ID_CNS_CS	= 4,
 	NVME_CTRL_DIRTY_CAPABILITY	= 5,
 	NVME_CTRL_FROZEN		= 6,
+	NVME_CTRL_MARGINAL		= 7,
 };
 
 struct nvme_ctrl {
@@ -419,6 +420,11 @@ static inline enum nvme_ctrl_state nvme_ctrl_state(struct nvme_ctrl *ctrl)
 	return READ_ONCE(ctrl->state);
 }
 
+static inline bool nvme_ctrl_is_marginal(struct nvme_ctrl *ctrl)
+{
+	return test_bit(NVME_CTRL_MARGINAL, &ctrl->flags);
+}
+
 enum nvme_iopolicy {
 	NVME_IOPOLICY_NUMA,
 	NVME_IOPOLICY_RR,
diff --git a/include/linux/nvme-fc-driver.h b/include/linux/nvme-fc-driver.h
index 9f6acadfe0c8..bcd3b1e5a256 100644
--- a/include/linux/nvme-fc-driver.h
+++ b/include/linux/nvme-fc-driver.h
@@ -536,6 +536,9 @@ void nvme_fc_rescan_remoteport(struct nvme_fc_remote_port *remoteport);
 int nvme_fc_set_remoteport_devloss(struct nvme_fc_remote_port *remoteport,
 			u32 dev_loss_tmo);
 
+void nvme_fc_fpin_rcv(struct nvme_fc_local_port *localport,
+		      u32 fpin_len, char *fpin_buf);
+
 /*
  * Routine called to pass a NVME-FC LS request, received by the lldd,
  * to the nvme-fc transport.
-- 
2.35.3