[SCSI] zfcp: attach and release SAN nameserver port on demand

Changing the zfcp behaviour from always having the nameserver port
open to an on-demand strategy.  This strategy reduces the use of
limited resources like port connections. The patch provides a common
infrastructure which could be used for all WKA ports in future.

Also reduce the number of nameserver lookups by changing the zfcp
behaviour of always querying the nameserver for the corresponding
destination ID of the remote port.  If the destination ID has changed
during the reopen process we will be informed and then trigger a
nameserver query on demand.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 151 insertions, 64 deletions

diff --git a/drivers/s390/scsi/zfcp_fc.c b/drivers/s390/scsi/zfcp_fc.c
index 44456f74a12d..899e45b9e60b 100644
--- a/drivers/s390/scsi/zfcp_fc.c
+++ b/drivers/s390/scsi/zfcp_fc.c
@@ -39,6 +39,84 @@ struct zfcp_gpn_ft {
         struct scatterlist sg_resp[ZFCP_GPN_FT_BUFFERS];
 };
 
+struct zfcp_fc_ns_handler_data {
+        struct completion done;
+        void (*handler)(unsigned long);
+        unsigned long handler_data;
+};
+
+static int zfcp_wka_port_get(struct zfcp_wka_port *wka_port)
+{
+        if (mutex_lock_interruptible(&wka_port->mutex))
+                return -ERESTARTSYS;
+
+        if (wka_port->status != ZFCP_WKA_PORT_ONLINE) {
+                wka_port->status = ZFCP_WKA_PORT_OPENING;
+                if (zfcp_fsf_open_wka_port(wka_port))
+                        wka_port->status = ZFCP_WKA_PORT_OFFLINE;
+        }
+
+        mutex_unlock(&wka_port->mutex);
+
+        wait_event_timeout(
+                wka_port->completion_wq,
+                wka_port->status == ZFCP_WKA_PORT_ONLINE ||
+                wka_port->status == ZFCP_WKA_PORT_OFFLINE,
+                HZ >> 1);
+
+        if (wka_port->status == ZFCP_WKA_PORT_ONLINE) {
+                atomic_inc(&wka_port->refcount);
+                return 0;
+        }
+        return -EIO;
+}
+
+static void zfcp_wka_port_offline(struct work_struct *work)
+{
+        struct delayed_work *dw = container_of(work, struct delayed_work, work);
+        struct zfcp_wka_port *wka_port =
+                        container_of(dw, struct zfcp_wka_port, work);
+
+        wait_event(wka_port->completion_wq,
+                        atomic_read(&wka_port->refcount) == 0);
+
+        mutex_lock(&wka_port->mutex);
+        if ((atomic_read(&wka_port->refcount) != 0) ||
+            (wka_port->status != ZFCP_WKA_PORT_ONLINE))
+                goto out;
+
+        wka_port->status = ZFCP_WKA_PORT_CLOSING;
+        if (zfcp_fsf_close_wka_port(wka_port)) {
+                wka_port->status = ZFCP_WKA_PORT_OFFLINE;
+                wake_up(&wka_port->completion_wq);
+        }
+out:
+        mutex_unlock(&wka_port->mutex);
+}
+
+static void zfcp_wka_port_put(struct zfcp_wka_port *wka_port)
+{
+        if (atomic_dec_return(&wka_port->refcount) != 0)
+                return;
+        /* wait 10 miliseconds, other reqs might pop in */
+        schedule_delayed_work(&wka_port->work, HZ / 100);
+}
+
+void zfcp_fc_nameserver_init(struct zfcp_adapter *adapter)
+{
+        struct zfcp_wka_port *wka_port = &adapter->nsp;
+
+        init_waitqueue_head(&wka_port->completion_wq);
+
+        wka_port->adapter = adapter;
+        wka_port->d_id = ZFCP_DID_DIRECTORY_SERVICE;
+
+        wka_port->status = ZFCP_WKA_PORT_OFFLINE;
+        atomic_set(&wka_port->refcount, 0);
+        mutex_init(&wka_port->mutex);
+        INIT_DELAYED_WORK(&wka_port->work, zfcp_wka_port_offline);
+}
+
 static void _zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req, u32 range,
                                    struct fcp_rscn_element *elem)
 {
@@ -47,9 +125,6 @@ static void _zfcp_fc_incoming_rscn(struct zfcp_fsf_req *fsf_req, u32 range,
 
         read_lock_irqsave(&zfcp_data.config_lock, flags);
         list_for_each_entry(port, &fsf_req->adapter->port_list_head, list) {
-                if ((atomic_read(&port->status) & ZFCP_STATUS_PORT_WKA) ==
-                      ZFCP_STATUS_PORT_WKA)
-                        continue;
                 /* FIXME: ZFCP_STATUS_PORT_DID_DID check is racy */
                 if (!(atomic_read(&port->status) & ZFCP_STATUS_PORT_DID_DID))
                         /* Try to connect to unused ports anyway. */
@@ -158,7 +233,18 @@ void zfcp_fc_incoming_els(struct zfcp_fsf_req *fsf_req)
                 zfcp_fc_incoming_rscn(fsf_req);
 }
 
-static void zfcp_ns_gid_pn_handler(unsigned long data)
+static void zfcp_fc_ns_handler(unsigned long data)
+{
+        struct zfcp_fc_ns_handler_data *compl_rec =
+                        (struct zfcp_fc_ns_handler_data *) data;
+
+        if (compl_rec->handler)
+                compl_rec->handler(compl_rec->handler_data);
+
+        complete(&compl_rec->done);
+}
+
+static void zfcp_fc_ns_gid_pn_eval(unsigned long data)
 {
         struct zfcp_gid_pn_data *gid_pn = (struct zfcp_gid_pn_data *) data;
         struct zfcp_send_ct *ct = &gid_pn->ct;
@@ -167,43 +253,31 @@ static void zfcp_ns_gid_pn_handler(unsigned long data)
         struct zfcp_port *port = gid_pn->port;
 
         if (ct->status)
-                goto out;
+                return;
         if (ct_iu_resp->header.cmd_rsp_code != ZFCP_CT_ACCEPT) {
                 atomic_set_mask(ZFCP_STATUS_PORT_INVALID_WWPN, &port->status);
-                goto out;
+                return;
         }
         /* paranoia */
         if (ct_iu_req->wwpn != port->wwpn)
-                goto out;
+                return;
         /* looks like a valid d_id */
         port->d_id = ct_iu_resp->d_id & ZFCP_DID_MASK;
         atomic_set_mask(ZFCP_STATUS_PORT_DID_DID, &port->status);
-out:
-        mempool_free(gid_pn, port->adapter->pool.data_gid_pn);
 }
 
-/**
- * zfcp_fc_ns_gid_pn_request - initiate GID_PN nameserver request
- * @erp_action: pointer to zfcp_erp_action where GID_PN request is needed
- * return: -ENOMEM on error, 0 otherwise
- */
-int zfcp_fc_ns_gid_pn_request(struct zfcp_erp_action *erp_action)
+int static zfcp_fc_ns_gid_pn_request(struct zfcp_erp_action *erp_action,
+                                     struct zfcp_gid_pn_data *gid_pn)
 {
-        int ret;
-        struct zfcp_gid_pn_data *gid_pn;
         struct zfcp_adapter *adapter = erp_action->adapter;
-
-        gid_pn = mempool_alloc(adapter->pool.data_gid_pn, GFP_ATOMIC);
-        if (!gid_pn)
-                return -ENOMEM;
-
-        memset(gid_pn, 0, sizeof(*gid_pn));
+        struct zfcp_fc_ns_handler_data compl_rec;
+        int ret;
 
         /* setup parameters for send generic command */
         gid_pn->port = erp_action->port;
-        gid_pn->ct.port = adapter->nameserver_port;
-        gid_pn->ct.handler = zfcp_ns_gid_pn_handler;
-        gid_pn->ct.handler_data = (unsigned long) gid_pn;
+        gid_pn->ct.wka_port = &adapter->nsp;
+        gid_pn->ct.handler = zfcp_fc_ns_handler;
+        gid_pn->ct.handler_data = (unsigned long) &compl_rec;
         gid_pn->ct.timeout = ZFCP_NS_GID_PN_TIMEOUT;
         gid_pn->ct.req = &gid_pn->req;
         gid_pn->ct.resp = &gid_pn->resp;
@@ -223,10 +297,42 @@ int zfcp_fc_ns_gid_pn_request(struct zfcp_erp_action *erp_action)
         gid_pn->ct_iu_req.header.max_res_size = ZFCP_CT_MAX_SIZE;
         gid_pn->ct_iu_req.wwpn = erp_action->port->wwpn;
 
+        init_completion(&compl_rec.done);
+        compl_rec.handler = zfcp_fc_ns_gid_pn_eval;
+        compl_rec.handler_data = (unsigned long) gid_pn;
         ret = zfcp_fsf_send_ct(&gid_pn->ct, adapter->pool.fsf_req_erp,
                                erp_action);
+        if (!ret)
+                wait_for_completion(&compl_rec.done);
+        return ret;
+}
+
+/**
+ * zfcp_fc_ns_gid_pn_request - initiate GID_PN nameserver request
+ * @erp_action: pointer to zfcp_erp_action where GID_PN request is needed
+ * return: -ENOMEM on error, 0 otherwise
+ */
+int zfcp_fc_ns_gid_pn(struct zfcp_erp_action *erp_action)
+{
+        int ret;
+        struct zfcp_gid_pn_data *gid_pn;
+        struct zfcp_adapter *adapter = erp_action->adapter;
+
+        gid_pn = mempool_alloc(adapter->pool.data_gid_pn, GFP_ATOMIC);
+        if (!gid_pn)
+                return -ENOMEM;
+
+        memset(gid_pn, 0, sizeof(*gid_pn));
+
+        ret = zfcp_wka_port_get(&adapter->nsp);
         if (ret)
-                mempool_free(gid_pn, adapter->pool.data_gid_pn);
+                goto out;
+
+        ret = zfcp_fc_ns_gid_pn_request(erp_action, gid_pn);
+
+        zfcp_wka_port_put(&adapter->nsp);
+out:
+        mempool_free(gid_pn, adapter->pool.data_gid_pn);
         return ret;
 }
 
@@ -339,30 +445,6 @@ void zfcp_test_link(struct zfcp_port *port)
                 zfcp_erp_port_forced_reopen(port, 0, 65, NULL);
 }
 
-static int zfcp_scan_get_nameserver(struct zfcp_adapter *adapter)
-{
-        int ret;
-
-        if (!adapter->nameserver_port)
-                return -EINTR;
-
-        if (!(atomic_read(&adapter->nameserver_port->status) &
-              ZFCP_STATUS_COMMON_UNBLOCKED)) {
-                ret = zfcp_erp_port_reopen(adapter->nameserver_port, 0, 148,
-                                           NULL);
-                if (ret)
-                        return ret;
-                zfcp_erp_wait(adapter);
-        }
-        return !(atomic_read(&adapter->nameserver_port->status) &
-                 ZFCP_STATUS_COMMON_UNBLOCKED);
-}
-
-static void zfcp_gpn_ft_handler(unsigned long _done)
-{
-        complete((struct completion *)_done);
-}
-
 static void zfcp_free_sg_env(struct zfcp_gpn_ft *gpn_ft)
 {
         struct scatterlist *sg = &gpn_ft->sg_req;
@@ -404,7 +486,7 @@ static int zfcp_scan_issue_gpn_ft(struct zfcp_gpn_ft *gpn_ft,
 {
         struct zfcp_send_ct *ct = &gpn_ft->ct;
         struct ct_iu_gpn_ft_req *req = sg_virt(&gpn_ft->sg_req);
-        struct completion done;
+        struct zfcp_fc_ns_handler_data compl_rec;
         int ret;
 
         /* prepare CT IU for GPN_FT */
@@ -421,19 +503,20 @@ static int zfcp_scan_issue_gpn_ft(struct zfcp_gpn_ft *gpn_ft,
         req->fc4_type = ZFCP_CT_SCSI_FCP;
 
         /* prepare zfcp_send_ct */
-        ct->port = adapter->nameserver_port;
-        ct->handler = zfcp_gpn_ft_handler;
-        ct->handler_data = (unsigned long)&done;
+        ct->wka_port = &adapter->nsp;
+        ct->handler = zfcp_fc_ns_handler;
+        ct->handler_data = (unsigned long)&compl_rec;
         ct->timeout = 10;
         ct->req = &gpn_ft->sg_req;
         ct->resp = gpn_ft->sg_resp;
         ct->req_count = 1;
         ct->resp_count = ZFCP_GPN_FT_BUFFERS;
 
-        init_completion(&done);
+        init_completion(&compl_rec.done);
+        compl_rec.handler = NULL;
         ret = zfcp_fsf_send_ct(ct, NULL, NULL);
         if (!ret)
-                wait_for_completion(&done);
+                wait_for_completion(&compl_rec.done);
         return ret;
 }
 
@@ -443,8 +526,6 @@ static void zfcp_validate_port(struct zfcp_port *port)
 
         atomic_clear_mask(ZFCP_STATUS_COMMON_NOESC, &port->status);
 
-        if (port == adapter->nameserver_port)
-                return;
         if ((port->supported_classes != 0) || (port->units != 0)) {
                 zfcp_port_put(port);
                 return;
@@ -461,7 +542,7 @@ static int zfcp_scan_eval_gpn_ft(struct zfcp_gpn_ft *gpn_ft)
         struct scatterlist *sg = gpn_ft->sg_resp;
         struct ct_hdr *hdr = sg_virt(sg);
         struct gpn_ft_resp_acc *acc = sg_virt(sg);
-        struct zfcp_adapter *adapter = ct->port->adapter;
+        struct zfcp_adapter *adapter = ct->wka_port->adapter;
         struct zfcp_port *port, *tmp;
         u32 d_id;
         int ret = 0, x, last = 0;
@@ -491,6 +572,9 @@ static int zfcp_scan_eval_gpn_ft(struct zfcp_gpn_ft *gpn_ft)
                 d_id = acc->port_id[0] << 16 | acc->port_id[1] << 8 |
                        acc->port_id[2];
 
+                /* don't attach ports with a well known address */
+                if ((d_id & ZFCP_DID_WKA) == ZFCP_DID_WKA)
+                        continue;
                 /* skip the adapter's port and known remote ports */
                 if (acc->wwpn == fc_host_port_name(adapter->scsi_host))
                         continue;
@@ -529,13 +613,15 @@ int zfcp_scan_ports(struct zfcp_adapter *adapter)
         if (fc_host_port_type(adapter->scsi_host) != FC_PORTTYPE_NPORT)
                 return 0;
 
-        ret = zfcp_scan_get_nameserver(adapter);
+        ret = zfcp_wka_port_get(&adapter->nsp);
         if (ret)
                 return ret;
 
         gpn_ft = zfcp_alloc_sg_env();
-        if (!gpn_ft)
-                return -ENOMEM;
+        if (!gpn_ft) {
+                ret = -ENOMEM;
+                goto out;
+        }
 
         for (i = 0; i < 3; i++) {
                 ret = zfcp_scan_issue_gpn_ft(gpn_ft, adapter);
@@ -548,7 +634,8 @@ int zfcp_scan_ports(struct zfcp_adapter *adapter)
                 }
         }
         zfcp_free_sg_env(gpn_ft);
-
+out:
+        zfcp_wka_port_put(&adapter->nsp);
         return ret;
 }