[SCSI] libiscsi: modify libiscsi so it supports offloaded data paths

This patch modifies libiscsi, so drivers like bnx2i and iser can execute
a command from queuecommand/send_pdu instead of having to be queued to
be run in a workq.

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

1 files changed, 104 insertions, 75 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 4bc63c4b3c10..1e605de07cff 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -79,9 +79,11 @@ iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
                  * xmit thread
                  */
                 if (!list_empty(&session->leadconn->xmitqueue) ||
-                    !list_empty(&session->leadconn->mgmtqueue))
-                        scsi_queue_work(session->host,
-                                        &session->leadconn->xmitwork);
+                    !list_empty(&session->leadconn->mgmtqueue)) {
+                        if (!(session->tt->caps & CAP_DATA_PATH_OFFLOAD))
+                                scsi_queue_work(session->host,
+                                                &session->leadconn->xmitwork);
+                }
         }
 }
 EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);
@@ -298,8 +300,12 @@ static int iscsi_prep_scsi_cmd_pdu(struct iscsi_cmd_task *ctask)
         WARN_ON(hdrlength >= 256);
         hdr->hlength = hdrlength & 0xFF;
 
-        if (conn->session->tt->init_cmd_task(conn->ctask))
-                return EIO;
+        if (conn->session->tt->init_cmd_task &&
+            conn->session->tt->init_cmd_task(ctask))
+                return -EIO;
+
+        ctask->state = ISCSI_TASK_RUNNING;
+        list_move_tail(&ctask->running, &conn->run_list);
 
         conn->scsicmd_pdus_cnt++;
         debug_scsi("iscsi prep [%s cid %d sc %p cdb 0x%x itt 0x%x "
@@ -334,7 +340,9 @@ static void iscsi_complete_command(struct iscsi_cmd_task *ctask)
                 conn->ctask = NULL;
         list_del_init(&ctask->running);
         __kfifo_put(session->cmdpool.queue, (void*)&ctask, sizeof(void*));
-        sc->scsi_done(sc);
+
+        if (sc->scsi_done)
+                sc->scsi_done(sc);
 }
 
 static void __iscsi_get_ctask(struct iscsi_cmd_task *ctask)
@@ -403,6 +411,50 @@ void iscsi_free_mgmt_task(struct iscsi_conn *conn,
 }
 EXPORT_SYMBOL_GPL(iscsi_free_mgmt_task);
 
+static int iscsi_prep_mtask(struct iscsi_conn *conn,
+                            struct iscsi_mgmt_task *mtask)
+{
+        struct iscsi_session *session = conn->session;
+        struct iscsi_hdr *hdr = mtask->hdr;
+        struct iscsi_nopout *nop = (struct iscsi_nopout *)hdr;
+
+        if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
+                return -ENOTCONN;
+
+        if (hdr->opcode != (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) &&
+            hdr->opcode != (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
+                nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
+        /*
+         * pre-format CmdSN for outgoing PDU.
+         */
+        nop->cmdsn = cpu_to_be32(session->cmdsn);
+        if (hdr->itt != RESERVED_ITT) {
+                hdr->itt = build_itt(mtask->itt, session->age);
+                /*
+                 * TODO: We always use immediate, so we never hit this.
+                 * If we start to send tmfs or nops as non-immediate then
+                 * we should start checking the cmdsn numbers for mgmt tasks.
+                 */
+                if (conn->c_stage == ISCSI_CONN_STARTED &&
+                    !(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
+                        session->queued_cmdsn++;
+                        session->cmdsn++;
+                }
+        }
+
+        if (session->tt->init_mgmt_task)
+                session->tt->init_mgmt_task(conn, mtask);
+
+        if ((hdr->opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_LOGOUT)
+                session->state = ISCSI_STATE_LOGGING_OUT;
+
+        list_move_tail(&mtask->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,
+                   mtask->data_count);
+        return 0;
+}
+
 static struct iscsi_mgmt_task *
 __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                       char *data, uint32_t data_size)
@@ -429,6 +481,12 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                 if (!__kfifo_get(session->mgmtpool.queue,
                                  (void*)&mtask, sizeof(void*)))
                         return NULL;
+
+                if ((hdr->opcode == (ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE)) &&
+                     hdr->ttt == RESERVED_ITT) {
+                        conn->ping_mtask = mtask;
+                        conn->last_ping = jiffies;
+                }
         }
 
         if (data_size) {
@@ -440,6 +498,19 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
         memcpy(mtask->hdr, hdr, sizeof(struct iscsi_hdr));
         INIT_LIST_HEAD(&mtask->running);
         list_add_tail(&mtask->running, &conn->mgmtqueue);
+
+        if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
+                if (iscsi_prep_mtask(conn, mtask)) {
+                        iscsi_free_mgmt_task(conn, mtask);
+                        return NULL;
+                }
+
+                if (session->tt->xmit_mgmt_task(conn, mtask))
+                        mtask = NULL;
+
+        } else
+                scsi_queue_work(conn->session->host, &conn->xmitwork);
+
         return mtask;
 }
 
@@ -454,7 +525,6 @@ int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
         if (!__iscsi_conn_send_pdu(conn, hdr, data, data_size))
                 err = -EPERM;
         spin_unlock_bh(&session->lock);
-        scsi_queue_work(session->host, &conn->xmitwork);
         return err;
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_send_pdu);
@@ -581,17 +651,8 @@ static void iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
                 hdr.ttt = RESERVED_ITT;
 
         mtask = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
-        if (!mtask) {
+        if (!mtask)
                 iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n");
-                return;
-        }
-
-        /* only track our nops */
-        if (!rhdr) {
-                conn->ping_mtask = mtask;
-                conn->last_ping = jiffies;
-        }
-        scsi_queue_work(conn->session->host, &conn->xmitwork);
 }
 
 static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
@@ -868,56 +929,15 @@ void iscsi_conn_failure(struct iscsi_conn *conn, enum iscsi_err err)
 }
 EXPORT_SYMBOL_GPL(iscsi_conn_failure);
 
-static void iscsi_prep_mtask(struct iscsi_conn *conn,
-                             struct iscsi_mgmt_task *mtask)
-{
-        struct iscsi_session *session = conn->session;
-        struct iscsi_hdr *hdr = mtask->hdr;
-        struct iscsi_nopout *nop = (struct iscsi_nopout *)hdr;
-
-        if (hdr->opcode != (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) &&
-            hdr->opcode != (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
-                nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
-        /*
-         * pre-format CmdSN for outgoing PDU.
-         */
-        nop->cmdsn = cpu_to_be32(session->cmdsn);
-        if (hdr->itt != RESERVED_ITT) {
-                hdr->itt = build_itt(mtask->itt, session->age);
-                /*
-                 * TODO: We always use immediate, so we never hit this.
-                 * If we start to send tmfs or nops as non-immediate then
-                 * we should start checking the cmdsn numbers for mgmt tasks.
-                 */
-                if (conn->c_stage == ISCSI_CONN_STARTED &&
-                    !(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
-                        session->queued_cmdsn++;
-                        session->cmdsn++;
-                }
-        }
-
-        if (session->tt->init_mgmt_task)
-                session->tt->init_mgmt_task(conn, mtask);
-
-        debug_scsi("mgmtpdu [op 0x%x hdr->itt 0x%x datalen %d]\n",
-                   hdr->opcode & ISCSI_OPCODE_MASK, hdr->itt,
-                   mtask->data_count);
-}
-
 static int iscsi_xmit_mtask(struct iscsi_conn *conn)
 {
-        struct iscsi_hdr *hdr = conn->mtask->hdr;
         int rc;
 
-        if ((hdr->opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_LOGOUT)
-                conn->session->state = ISCSI_STATE_LOGGING_OUT;
         spin_unlock_bh(&conn->session->lock);
-
         rc = conn->session->tt->xmit_mgmt_task(conn, conn->mtask);
         spin_lock_bh(&conn->session->lock);
         if (rc)
                 return rc;
-
         /* done with this in-progress mtask */
         conn->mtask = NULL;
         return 0;
@@ -961,7 +981,8 @@ static int iscsi_xmit_ctask(struct iscsi_conn *conn)
  * @ctask: ctask to requeue
  *
  * LLDs that need to run a ctask from the session workqueue should call
- * this. The session lock must be held.
+ * this. The session lock must be held. This should only be called
+ * by software drivers.
  */
 void iscsi_requeue_ctask(struct iscsi_cmd_task *ctask)
 {
@@ -1013,14 +1034,11 @@ check_mgmt:
         while (!list_empty(&conn->mgmtqueue)) {
                 conn->mtask = list_entry(conn->mgmtqueue.next,
                                          struct iscsi_mgmt_task, running);
-                if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
+                if (iscsi_prep_mtask(conn, conn->mtask)) {
                         iscsi_free_mgmt_task(conn, conn->mtask);
                         conn->mtask = NULL;
                         continue;
                 }
-
-                iscsi_prep_mtask(conn, conn->mtask);
-                list_move_tail(conn->mgmtqueue.next, &conn->mgmt_run_list);
                 rc = iscsi_xmit_mtask(conn);
                 if (rc)
                         goto again;
@@ -1041,9 +1059,6 @@ check_mgmt:
                         fail_command(conn, conn->ctask, DID_ABORT << 16);
                         continue;
                 }
-
-                conn->ctask->state = ISCSI_TASK_RUNNING;
-                list_move_tail(conn->xmitqueue.next, &conn->run_list);
                 rc = iscsi_xmit_ctask(conn);
                 if (rc)
                         goto again;
@@ -1192,8 +1207,6 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
                 reason = FAILURE_OOM;
                 goto reject;
         }
-        session->queued_cmdsn++;
-
         sc->SCp.phase = session->age;
         sc->SCp.ptr = (char *)ctask;
 
@@ -1202,11 +1215,26 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
         ctask->conn = conn;
         ctask->sc = sc;
         INIT_LIST_HEAD(&ctask->running);
-
         list_add_tail(&ctask->running, &conn->xmitqueue);
-        spin_unlock(&session->lock);
 
-        scsi_queue_work(host, &conn->xmitwork);
+        if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
+                if (iscsi_prep_scsi_cmd_pdu(ctask)) {
+                        sc->result = DID_ABORT << 16;
+                        sc->scsi_done = NULL;
+                        iscsi_complete_command(ctask);
+                        goto fault;
+                }
+                if (session->tt->xmit_cmd_task(conn, ctask)) {
+                        sc->scsi_done = NULL;
+                        iscsi_complete_command(ctask);
+                        reason = FAILURE_SESSION_NOT_READY;
+                        goto reject;
+                }
+        } else
+                scsi_queue_work(session->host, &conn->xmitwork);
+
+        session->queued_cmdsn++;
+        spin_unlock(&session->lock);
         spin_lock(host->host_lock);
         return 0;
 
@@ -1225,7 +1253,7 @@ fault:
                 scsi_out(sc)->resid = scsi_out(sc)->length;
                 scsi_in(sc)->resid = scsi_in(sc)->length;
         }
-        sc->scsi_done(sc);
+        done(sc);
         spin_lock(host->host_lock);
         return 0;
 }
@@ -1344,7 +1372,6 @@ static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
 
         spin_unlock_bh(&session->lock);
         mutex_unlock(&session->eh_mutex);
-        scsi_queue_work(session->host, &conn->xmitwork);
 
         /*
          * block eh thread until:
@@ -1412,14 +1439,16 @@ static void fail_all_commands(struct iscsi_conn *conn, unsigned lun,
 void iscsi_suspend_tx(struct iscsi_conn *conn)
 {
         set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-        scsi_flush_work(conn->session->host);
+        if (!(conn->session->tt->caps & CAP_DATA_PATH_OFFLOAD))
+                scsi_flush_work(conn->session->host);
 }
 EXPORT_SYMBOL_GPL(iscsi_suspend_tx);
 
 static void iscsi_start_tx(struct iscsi_conn *conn)
 {
         clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
-        scsi_queue_work(conn->session->host, &conn->xmitwork);
+        if (!(conn->session->tt->caps & CAP_DATA_PATH_OFFLOAD))
+                scsi_queue_work(conn->session->host, &conn->xmitwork);
 }
 
 static enum scsi_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *scmd)