[SCSI] tgt: add I_T nexus support

tgt uses scsi_host as I_T nexus. This works for ibmvstgt because it
creates one scsi_host for one initiator. However, other target drivers
don't work like that.

This adds I_T nexus support, which enable one scsi_host to handle
multiple initiators. New scsi_tgt_it_nexus_create/destroy functions
are expected be called transport classes. For example, ibmvstgt
creates an initiator remote port, then the srp transport calls
tgt_it_nexus_create. tgt doesn't manages I_T nexus, instead it tells
tgtd, user-space daemon, to create a new I_T nexus.

On the receiving the response from tgtd, tgt calls
shost->transportt->it_nexus_response. transports should notify a
lld. The srp transport uses it_nexus_response callback in
srp_function_template to do that.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

4 files changed, 39 insertions, 12 deletions

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index 3b8a6a85c2f8..89c40c4bd5c4 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -146,7 +146,7 @@ struct scsi_host_template {
                                   void (*done)(struct scsi_cmnd *));
 
         /* Used as callback for the completion of task management request. */
-        int (* tsk_mgmt_response)(u64 mid, int result);
+        int (* tsk_mgmt_response)(struct Scsi_Host *, u64, u64 mid, int result);
 
         /*
          * This is an error handling strategy routine.  You don't need to
diff --git a/include/scsi/scsi_tgt.h b/include/scsi/scsi_tgt.h
index 4f4427937af2..d0fefb96158f 100644
--- a/include/scsi/scsi_tgt.h
+++ b/include/scsi/scsi_tgt.h
@@ -11,9 +11,11 @@ struct scsi_lun;
 extern struct Scsi_Host *scsi_tgt_cmd_to_host(struct scsi_cmnd *);
 extern int scsi_tgt_alloc_queue(struct Scsi_Host *);
 extern void scsi_tgt_free_queue(struct Scsi_Host *);
-extern int scsi_tgt_queue_command(struct scsi_cmnd *, struct scsi_lun *, u64);
-extern int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *, int, u64, struct scsi_lun *,
-                                     void *);
+extern int scsi_tgt_queue_command(struct scsi_cmnd *, u64, struct scsi_lun *, u64);
+extern int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *, u64, int, u64,
+                                     struct scsi_lun *, void *);
 extern struct scsi_cmnd *scsi_host_get_command(struct Scsi_Host *,
                                                enum dma_data_direction, gfp_t);
 extern void scsi_host_put_command(struct Scsi_Host *, struct scsi_cmnd *);
+extern int scsi_tgt_it_nexus_create(struct Scsi_Host *, u64, char *);
+extern int scsi_tgt_it_nexus_destroy(struct Scsi_Host *, u64);
diff --git a/include/scsi/scsi_tgt_if.h b/include/scsi/scsi_tgt_if.h
index 4cf9dff29a2f..f2ee7c238a45 100644
--- a/include/scsi/scsi_tgt_if.h
+++ b/include/scsi/scsi_tgt_if.h
@@ -23,13 +23,15 @@
 #define __SCSI_TARGET_IF_H
 
 /* user -> kernel */
-#define TGT_UEVENT_CMD_RSP      0x0001
-#define TGT_UEVENT_TSK_MGMT_RSP 0x0002
+#define TGT_UEVENT_CMD_RSP              0x0001
+#define TGT_UEVENT_IT_NEXUS_RSP         0x0002
+#define TGT_UEVENT_TSK_MGMT_RSP         0x0003
 
 /* kernel -> user */
-#define TGT_KEVENT_CMD_REQ      0x1001
-#define TGT_KEVENT_CMD_DONE     0x1002
-#define TGT_KEVENT_TSK_MGMT_REQ 0x1003
+#define TGT_KEVENT_CMD_REQ              0x1001
+#define TGT_KEVENT_CMD_DONE             0x1002
+#define TGT_KEVENT_IT_NEXUS_REQ         0x1003
+#define TGT_KEVENT_TSK_MGMT_REQ         0x1004
 
 struct tgt_event_hdr {
         uint16_t version;
@@ -46,6 +48,7 @@ struct tgt_event {
                 struct {
                         int host_no;
                         int result;
+                        aligned_u64 itn_id;
                         aligned_u64 tag;
                         aligned_u64 uaddr;
                         aligned_u64 sense_uaddr;
@@ -55,15 +58,22 @@ struct tgt_event {
                 } cmd_rsp;
                 struct {
                         int host_no;
-                        aligned_u64 mid;
                         int result;
+                        aligned_u64 itn_id;
+                        aligned_u64 mid;
                 } tsk_mgmt_rsp;
-
+                struct {
+                        __s32 host_no;
+                        __s32 result;
+                        aligned_u64 itn_id;
+                        __u32 function;
+                } it_nexus_rsp;
 
                 /* kernel -> user */
                 struct {
                         int host_no;
                         uint32_t data_len;
+                        aligned_u64 itn_id;
                         uint8_t scb[16];
                         uint8_t lun[8];
                         int attribute;
@@ -71,16 +81,25 @@ struct tgt_event {
                 } cmd_req;
                 struct {
                         int host_no;
-                        aligned_u64 tag;
                         int result;
+                        aligned_u64 itn_id;
+                        aligned_u64 tag;
                 } cmd_done;
                 struct {
                         int host_no;
                         int function;
+                        aligned_u64 itn_id;
                         aligned_u64 tag;
                         uint8_t lun[8];
                         aligned_u64 mid;
                 } tsk_mgmt_req;
+                struct {
+                        __s32 host_no;
+                        __u32 function;
+                        aligned_u64 itn_id;
+                        __u32 max_cmds;
+                        __u8 initiator_id[16];
+                } it_nexus_req;
         } p;
 } __attribute__ ((aligned (sizeof(uint64_t))));
 
diff --git a/include/scsi/scsi_transport.h b/include/scsi/scsi_transport.h
index 3c18baa65a72..af5b3e15e64e 100644
--- a/include/scsi/scsi_transport.h
+++ b/include/scsi/scsi_transport.h
@@ -65,6 +65,12 @@ struct scsi_transport_template {
          * EH_NOT_HANDLED       Begin normal error recovery
          */
         enum scsi_eh_timer_return (* eh_timed_out)(struct scsi_cmnd *);
+
+        /*
+         * Used as callback for the completion of i_t_nexus request
+         * for target drivers.
+         */
+        int (* it_nexus_response)(struct Scsi_Host *, u64, int);
 };
 
 #define transport_class_to_shost(tc) \