[SCSI] libiscsi: prepare libiscsi for new offload engines by modifying unsol data code

cxgb3i offloads data transfers. It does not offload the entire scsi/iscsi
procssing like qla4xxx and it does not offload the iscsi sequence
processing like how bnx2i does. cxgb3i relies on iscsi_tcp for the
seqeunce handling so this changes how we transfer unsolicitied data by
adding a common r2t struct and helpers.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

3 files changed, 156 insertions, 70 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 3fdee7370ccc..80cbcdce7fa3 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -88,34 +88,47 @@ iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
 }
 EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);
 
-void iscsi_prep_unsolicit_data_pdu(struct iscsi_task *task,
-                                   struct iscsi_data *hdr)
+/**
+ * iscsi_prep_data_out_pdu - initialize Data-Out
+ * @task: scsi command task
+ * @r2t: R2T info
+ * @hdr: iscsi data in pdu
+ *
+ * Notes:
+ *      Initialize Data-Out within this R2T sequence and finds
+ *      proper data_offset within this SCSI command.
+ *
+ *      This function is called with connection lock taken.
+ **/
+void iscsi_prep_data_out_pdu(struct iscsi_task *task, struct iscsi_r2t_info *r2t,
+                           struct iscsi_data *hdr)
 {
         struct iscsi_conn *conn = task->conn;
+        unsigned int left = r2t->data_length - r2t->sent;
+
+        task->hdr_len = sizeof(struct iscsi_data);
 
         memset(hdr, 0, sizeof(struct iscsi_data));
-        hdr->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
-        hdr->datasn = cpu_to_be32(task->unsol_datasn);
-        task->unsol_datasn++;
+        hdr->ttt = r2t->ttt;
+        hdr->datasn = cpu_to_be32(r2t->datasn);
+        r2t->datasn++;
         hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
-        memcpy(hdr->lun, task->hdr->lun, sizeof(hdr->lun));
-
-        hdr->itt = task->hdr->itt;
-        hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
-        hdr->offset = cpu_to_be32(task->unsol_offset);
-
-        if (task->unsol_count > conn->max_xmit_dlength) {
+        memcpy(hdr->lun, task->lun, sizeof(hdr->lun));
+        hdr->itt = task->hdr_itt;
+        hdr->exp_statsn = r2t->exp_statsn;
+        hdr->offset = cpu_to_be32(r2t->data_offset + r2t->sent);
+        if (left > conn->max_xmit_dlength) {
                 hton24(hdr->dlength, conn->max_xmit_dlength);
-                task->data_count = conn->max_xmit_dlength;
-                task->unsol_offset += task->data_count;
+                r2t->data_count = conn->max_xmit_dlength;
                 hdr->flags = 0;
         } else {
-                hton24(hdr->dlength, task->unsol_count);
-                task->data_count = task->unsol_count;
+                hton24(hdr->dlength, left);
+                r2t->data_count = left;
                 hdr->flags = ISCSI_FLAG_CMD_FINAL;
         }
+        conn->dataout_pdus_cnt++;
 }
-EXPORT_SYMBOL_GPL(iscsi_prep_unsolicit_data_pdu);
+EXPORT_SYMBOL_GPL(iscsi_prep_data_out_pdu);
 
 static int iscsi_add_hdr(struct iscsi_task *task, unsigned len)
 {
@@ -206,11 +219,17 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
 {
         struct iscsi_conn *conn = task->conn;
         struct iscsi_session *session = conn->session;
-        struct iscsi_cmd *hdr = task->hdr;
         struct scsi_cmnd *sc = task->sc;
+        struct iscsi_cmd *hdr;
         unsigned hdrlength, cmd_len;
         int rc;
 
+        rc = conn->session->tt->alloc_pdu(task);
+        if (rc)
+                return rc;
+        hdr = (struct iscsi_cmd *) task->hdr;
+        memset(hdr, 0, sizeof(*hdr));
+
         task->hdr_len = 0;
         rc = iscsi_add_hdr(task, sizeof(*hdr));
         if (rc)
@@ -218,8 +237,9 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
         hdr->opcode = ISCSI_OP_SCSI_CMD;
         hdr->flags = ISCSI_ATTR_SIMPLE;
         int_to_scsilun(sc->device->lun, (struct scsi_lun *)hdr->lun);
-        hdr->itt = build_itt(task->itt, session->age);
-        hdr->cmdsn = cpu_to_be32(session->cmdsn);
+        memcpy(task->lun, hdr->lun, sizeof(task->lun));
+        hdr->itt = task->hdr_itt = build_itt(task->itt, session->age);
+        hdr->cmdsn = task->cmdsn = cpu_to_be32(session->cmdsn);
         session->cmdsn++;
         hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
         cmd_len = sc->cmd_len;
@@ -242,6 +262,8 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
         }
         if (sc->sc_data_direction == DMA_TO_DEVICE) {
                 unsigned out_len = scsi_out(sc)->length;
+                struct iscsi_r2t_info *r2t = &task->unsol_r2t;
+
                 hdr->data_length = cpu_to_be32(out_len);
                 hdr->flags |= ISCSI_FLAG_CMD_WRITE;
                 /*
@@ -254,13 +276,11 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
                  *                      without R2T ack right after
                  *                      immediate data
                  *
-                 *      r2t_data_count  bytes to be sent via R2T ack's
+                 *      r2t data_length bytes to be sent via R2T ack's
                  *
                  *      pad_count       bytes to be sent as zero-padding
                  */
-                task->unsol_count = 0;
-                task->unsol_offset = 0;
-                task->unsol_datasn = 0;
+                memset(r2t, 0, sizeof(*r2t));
 
                 if (session->imm_data_en) {
                         if (out_len >= session->first_burst)
@@ -274,12 +294,14 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
                         zero_data(hdr->dlength);
 
                 if (!session->initial_r2t_en) {
-                        task->unsol_count = min(session->first_burst, out_len)
-                                                             - task->imm_count;
-                        task->unsol_offset = task->imm_count;
+                        r2t->data_length = min(session->first_burst, out_len) -
+                                               task->imm_count;
+                        r2t->data_offset = task->imm_count;
+                        r2t->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
+                        r2t->exp_statsn = cpu_to_be32(conn->exp_statsn);
                 }
 
-                if (!task->unsol_count)
+                if (!task->unsol_r2t.data_length)
                         /* No unsolicit Data-Out's */
                         hdr->flags |= ISCSI_FLAG_CMD_FINAL;
         } else {
@@ -300,8 +322,7 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
         WARN_ON(hdrlength >= 256);
         hdr->hlength = hdrlength & 0xFF;
 
-        if (conn->session->tt->init_task &&
-            conn->session->tt->init_task(task))
+        if (session->tt->init_task && session->tt->init_task(task))
                 return -EIO;
 
         task->state = ISCSI_TASK_RUNNING;
@@ -332,6 +353,7 @@ static void iscsi_complete_command(struct iscsi_task *task)
         struct iscsi_session *session = conn->session;
         struct scsi_cmnd *sc = task->sc;
 
+        session->tt->cleanup_task(task);
         list_del_init(&task->running);
         task->state = ISCSI_TASK_COMPLETED;
         task->sc = NULL;
@@ -402,8 +424,6 @@ static void fail_command(struct iscsi_conn *conn, struct iscsi_task *task,
                  * the cmd in the sequencing
                  */
                 conn->session->queued_cmdsn--;
-        else
-                conn->session->tt->cleanup_task(conn, task);
 
         sc->result = err;
         if (!scsi_bidi_cmnd(sc))
@@ -423,7 +443,7 @@ static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
                                 struct iscsi_task *task)
 {
         struct iscsi_session *session = conn->session;
-        struct iscsi_hdr *hdr = (struct iscsi_hdr *)task->hdr;
+        struct iscsi_hdr *hdr = task->hdr;
         struct iscsi_nopout *nop = (struct iscsi_nopout *)hdr;
 
         if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
@@ -456,6 +476,7 @@ static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
         if ((hdr->opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_LOGOUT)
                 session->state = ISCSI_STATE_LOGGING_OUT;
 
+        task->state = ISCSI_TASK_RUNNING;
         list_move_tail(&task->running, &conn->mgmt_run_list);
         debug_scsi("mgmtpdu [op 0x%x hdr->itt 0x%x datalen %d]\n",
                    hdr->opcode & ISCSI_OPCODE_MASK, hdr->itt,
@@ -505,23 +526,38 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
         } else
                 task->data_count = 0;
 
+        if (conn->session->tt->alloc_pdu(task)) {
+                iscsi_conn_printk(KERN_ERR, conn, "Could not allocate "
+                                 "pdu for mgmt task.\n");
+                goto requeue_task;
+        }
+        task->hdr_len = sizeof(struct iscsi_hdr);
+
         memcpy(task->hdr, hdr, sizeof(struct iscsi_hdr));
         INIT_LIST_HEAD(&task->running);
         list_add_tail(&task->running, &conn->mgmtqueue);
 
         if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
-                if (iscsi_prep_mgmt_task(conn, task)) {
-                        __iscsi_put_task(task);
-                        return NULL;
-                }
+                if (iscsi_prep_mgmt_task(conn, task))
+                        goto free_task;
 
                 if (session->tt->xmit_task(task))
-                        task = NULL;
+                        goto free_task;
 
         } else
                 scsi_queue_work(conn->session->host, &conn->xmitwork);
 
         return task;
+
+free_task:
+        __iscsi_put_task(task);
+        return NULL;
+
+requeue_task:
+        if (task != conn->login_task)
+                __kfifo_put(session->cmdpool.queue, (void*)&task,
+                            sizeof(void*));
+        return NULL;
 }
 
 int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
@@ -1136,8 +1172,13 @@ check_mgmt:
                         fail_command(conn, conn->task, DID_IMM_RETRY << 16);
                         continue;
                 }
-                if (iscsi_prep_scsi_cmd_pdu(conn->task)) {
-                        fail_command(conn, conn->task, DID_ABORT << 16);
+                rc = iscsi_prep_scsi_cmd_pdu(conn->task);
+                if (rc) {
+                        if (rc == -ENOMEM) {
+                                conn->task = NULL;
+                                goto again;
+                        } else
+                                fail_command(conn, conn->task, DID_ABORT << 16);
                         continue;
                 }
                 rc = iscsi_xmit_task(conn);
@@ -1195,6 +1236,26 @@ static void iscsi_xmitworker(struct work_struct *work)
         } while (rc >= 0 || rc == -EAGAIN);
 }
 
+static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn,
+                                                  struct scsi_cmnd *sc)
+{
+        struct iscsi_task *task;
+
+        if (!__kfifo_get(conn->session->cmdpool.queue,
+                         (void *) &task, sizeof(void *)))
+                return NULL;
+
+        sc->SCp.phase = conn->session->age;
+        sc->SCp.ptr = (char *) task;
+
+        atomic_set(&task->refcount, 1);
+        task->state = ISCSI_TASK_PENDING;
+        task->conn = conn;
+        task->sc = sc;
+        INIT_LIST_HEAD(&task->running);
+        return task;
+}
+
 enum {
         FAILURE_BAD_HOST = 1,
         FAILURE_SESSION_FAILED,
@@ -1281,33 +1342,27 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
                 goto reject;
         }
 
-        if (!__kfifo_get(session->cmdpool.queue, (void*)&task,
-                         sizeof(void*))) {
+        task = iscsi_alloc_task(conn, sc);
+        if (!task) {
                 reason = FAILURE_OOM;
                 goto reject;
         }
-        sc->SCp.phase = session->age;
-        sc->SCp.ptr = (char *)task;
-
-        atomic_set(&task->refcount, 1);
-        task->state = ISCSI_TASK_PENDING;
-        task->conn = conn;
-        task->sc = sc;
-        INIT_LIST_HEAD(&task->running);
         list_add_tail(&task->running, &conn->xmitqueue);
 
         if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
-                if (iscsi_prep_scsi_cmd_pdu(task)) {
-                        sc->result = DID_ABORT << 16;
-                        sc->scsi_done = NULL;
-                        iscsi_complete_command(task);
-                        goto fault;
+                reason = iscsi_prep_scsi_cmd_pdu(task);
+                if (reason) {
+                        if (reason == -ENOMEM) {
+                                reason = FAILURE_OOM;
+                                goto prepd_reject;
+                        } else {
+                                sc->result = DID_ABORT << 16;
+                                goto prepd_fault;
+                        }
                 }
                 if (session->tt->xmit_task(task)) {
-                        sc->scsi_done = NULL;
-                        iscsi_complete_command(task);
                         reason = FAILURE_SESSION_NOT_READY;
-                        goto reject;
+                        goto prepd_reject;
                 }
         } else
                 scsi_queue_work(session->host, &conn->xmitwork);
@@ -1317,12 +1372,18 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
         spin_lock(host->host_lock);
         return 0;
 
+prepd_reject:
+        sc->scsi_done = NULL;
+        iscsi_complete_command(task);
 reject:
         spin_unlock(&session->lock);
         debug_scsi("cmd 0x%x rejected (%d)\n", sc->cmnd[0], reason);
         spin_lock(host->host_lock);
         return SCSI_MLQUEUE_TARGET_BUSY;
 
+prepd_fault:
+        sc->scsi_done = NULL;
+        iscsi_complete_command(task);
 fault:
         spin_unlock(&session->lock);
         debug_scsi("iscsi: cmd 0x%x is not queued (%d)\n", sc->cmnd[0], reason);
@@ -1634,9 +1695,9 @@ static void iscsi_prep_abort_task_pdu(struct iscsi_task *task,
         hdr->opcode = ISCSI_OP_SCSI_TMFUNC | ISCSI_OP_IMMEDIATE;
         hdr->flags = ISCSI_TM_FUNC_ABORT_TASK & ISCSI_FLAG_TM_FUNC_MASK;
         hdr->flags |= ISCSI_FLAG_CMD_FINAL;
-        memcpy(hdr->lun, task->hdr->lun, sizeof(hdr->lun));
-        hdr->rtt = task->hdr->itt;
-        hdr->refcmdsn = task->hdr->cmdsn;
+        memcpy(hdr->lun, task->lun, sizeof(hdr->lun));
+        hdr->rtt = task->hdr_itt;
+        hdr->refcmdsn = task->cmdsn;
 }
 
 int iscsi_eh_abort(struct scsi_cmnd *sc)
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 61e53f14f7e1..51500573c0b8 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -93,24 +93,38 @@ enum {
         ISCSI_TASK_RUNNING,
 };
 
+struct iscsi_r2t_info {
+        __be32                  ttt;            /* copied from R2T */
+        __be32                  exp_statsn;     /* copied from R2T */
+        uint32_t                data_length;    /* copied from R2T */
+        uint32_t                data_offset;    /* copied from R2T */
+        int                     data_count;     /* DATA-Out payload progress */
+        int                     datasn;
+        /* LLDs should set/update these values */
+        int                     sent;           /* R2T sequence progress */
+};
+
 struct iscsi_task {
         /*
          * Because LLDs allocate their hdr differently, this is a pointer
          * and length to that storage. It must be setup at session
          * creation time.
          */
-        struct iscsi_cmd        *hdr;
+        struct iscsi_hdr        *hdr;
         unsigned short          hdr_max;
         unsigned short          hdr_len;        /* accumulated size of hdr used */
+        /* copied values in case we need to send tmfs */
+        itt_t                   hdr_itt;
+        __be32                  cmdsn;
+        uint8_t                 lun[8];
+
         int                     itt;            /* this ITT */
 
-        uint32_t                unsol_datasn;
         unsigned                imm_count;      /* imm-data (bytes)   */
-        unsigned                unsol_count;    /* unsolicited (bytes)*/
         /* offset in unsolicited stream (bytes); */
-        unsigned                unsol_offset;
-        unsigned                data_count;     /* remaining Data-Out */
+        struct iscsi_r2t_info   unsol_r2t;
         char                    *data;          /* mgmt payload */
+        unsigned                data_count;
         struct scsi_cmnd        *sc;            /* associated SCSI cmd*/
         struct iscsi_conn       *conn;          /* used connection    */
 
@@ -121,6 +135,11 @@ struct iscsi_task {
         void                    *dd_data;       /* driver/transport data */
 };
 
+static inline int iscsi_task_has_unsol_data(struct iscsi_task *task)
+{
+        return task->unsol_r2t.data_length > task->unsol_r2t.sent;
+}
+
 static inline void* iscsi_next_hdr(struct iscsi_task *task)
 {
         return (void*)task->hdr + task->hdr_len;
@@ -376,8 +395,9 @@ extern void iscsi_suspend_tx(struct iscsi_conn *conn);
  * pdu and task processing
  */
 extern void iscsi_update_cmdsn(struct iscsi_session *, struct iscsi_nopin *);
-extern void iscsi_prep_unsolicit_data_pdu(struct iscsi_task *,
-                                        struct iscsi_data *hdr);
+extern void iscsi_prep_data_out_pdu(struct iscsi_task *task,
+                                    struct iscsi_r2t_info *r2t,
+                                    struct iscsi_data *hdr);
 extern int iscsi_conn_send_pdu(struct iscsi_cls_conn *, struct iscsi_hdr *,
                                 char *, uint32_t);
 extern int iscsi_complete_pdu(struct iscsi_conn *, struct iscsi_hdr *,
diff --git a/include/scsi/scsi_transport_iscsi.h b/include/scsi/scsi_transport_iscsi.h
index c667cc396545..c928234c018f 100644
--- a/include/scsi/scsi_transport_iscsi.h
+++ b/include/scsi/scsi_transport_iscsi.h
@@ -113,10 +113,15 @@ struct iscsi_transport {
                          char *data, uint32_t data_size);
         void (*get_stats) (struct iscsi_cls_conn *conn,
                            struct iscsi_stats *stats);
+
         int (*init_task) (struct iscsi_task *task);
         int (*xmit_task) (struct iscsi_task *task);
-        void (*cleanup_task) (struct iscsi_conn *conn,
-                                  struct iscsi_task *task);
+        void (*cleanup_task) (struct iscsi_task *task);
+
+        int (*alloc_pdu) (struct iscsi_task *task);
+        int (*xmit_pdu) (struct iscsi_task *task);
+        int (*init_pdu) (struct iscsi_task *task, unsigned int offset,
+                         unsigned int count);
         void (*session_recovery_timedout) (struct iscsi_cls_session *session);
         struct iscsi_endpoint *(*ep_connect) (struct sockaddr *dst_addr,
                                               int non_blocking);