[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, 23 insertions, 8 deletions

diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index 699ecaf2e503..0d6a388882d4 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -253,6 +253,7 @@ struct zfcp_ls_adisc {
 #define ZFCP_STATUS_ADAPTER_LINK_UNPLUGGED      0x00000200
 
 /* FC-PH/FC-GS well-known address identifiers for generic services */
+#define ZFCP_DID_WKA                            0xFFFFF0
 #define ZFCP_DID_MANAGEMENT_SERVICE             0xFFFFFA
 #define ZFCP_DID_TIME_SERVICE                   0xFFFFFB
 #define ZFCP_DID_DIRECTORY_SERVICE              0xFFFFFC
@@ -264,13 +265,15 @@ struct zfcp_ls_adisc {
 #define ZFCP_STATUS_PORT_DID_DID                0x00000002
 #define ZFCP_STATUS_PORT_PHYS_CLOSING           0x00000004
 #define ZFCP_STATUS_PORT_NO_WWPN                0x00000008
-#define ZFCP_STATUS_PORT_NO_SCSI_ID             0x00000010
 #define ZFCP_STATUS_PORT_INVALID_WWPN           0x00000020
 
-/* for ports with well known addresses */
-#define ZFCP_STATUS_PORT_WKA \
-                (ZFCP_STATUS_PORT_NO_WWPN | \
-                 ZFCP_STATUS_PORT_NO_SCSI_ID)
+/* well known address (WKA) port status*/
+enum zfcp_wka_status {
+        ZFCP_WKA_PORT_OFFLINE,
+        ZFCP_WKA_PORT_CLOSING,
+        ZFCP_WKA_PORT_OPENING,
+        ZFCP_WKA_PORT_ONLINE,
+};
 
 /* logical unit status */
 #define ZFCP_STATUS_UNIT_SHARED                 0x00000004
@@ -340,7 +343,7 @@ typedef void (*zfcp_send_ct_handler_t)(unsigned long);
 
 /**
  * struct zfcp_send_ct - used to pass parameters to function zfcp_fsf_send_ct
- * @port: port where the request is sent to
+ * @wka_port: port where the request is sent to
  * @req: scatter-gather list for request
  * @resp: scatter-gather list for response
  * @req_count: number of elements in request scatter-gather list
@@ -352,7 +355,7 @@ typedef void (*zfcp_send_ct_handler_t)(unsigned long);
  * @status: used to pass error status to calling function
  */
 struct zfcp_send_ct {
-        struct zfcp_port *port;
+        struct zfcp_wka_port *wka_port;
         struct scatterlist *req;
         struct scatterlist *resp;
         unsigned int req_count;
@@ -406,6 +409,17 @@ struct zfcp_send_els {
         int status;
 };
 
+struct zfcp_wka_port {
+        struct zfcp_adapter     *adapter;
+        wait_queue_head_t       completion_wq;
+        enum zfcp_wka_status    status;
+        atomic_t                refcount;
+        u32                     d_id;
+        u32                     handle;
+        struct mutex            mutex;
+        struct delayed_work     work;
+};
+
 struct zfcp_qdio_queue {
         struct qdio_buffer *sbal[QDIO_MAX_BUFFERS_PER_Q]; /* SBALs */
         u8                 first;             /* index of next free bfr
@@ -496,7 +510,7 @@ struct zfcp_adapter {
                                                       actions */
         u32                     erp_low_mem_count; /* nr of erp actions waiting
                                                       for memory */
-        struct zfcp_port        *nameserver_port;  /* adapter's nameserver */
+        struct zfcp_wka_port    nsp;               /* adapter's nameserver */
         debug_info_t            *rec_dbf;
         debug_info_t            *hba_dbf;
         debug_info_t            *san_dbf;          /* debug feature areas */
@@ -540,6 +554,7 @@ struct zfcp_port {
         atomic_t               erp_counter;
         u32                    maxframe_size;
         u32                    supported_classes;
+        struct work_struct     gid_pn_work;
 };
 
 struct zfcp_unit {