[SCSI] libiscsi: fix cmd seqeunce number checking

We should not be checking the cmd windown for just handling r2t responses.
And if the window closes in on us, always have scsi-ml requeue the command
from our queuecommand function.

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

2 files changed, 28 insertions, 21 deletions

diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
index 271a2d671b89..5606d1e62978 100644
--- a/drivers/scsi/libiscsi.c
+++ b/drivers/scsi/libiscsi.c
@@ -596,9 +596,16 @@ static void iscsi_prep_mtask(struct iscsi_conn *conn,
         nop->cmdsn = cpu_to_be32(session->cmdsn);
         if (hdr->itt != RESERVED_ITT) {
                 hdr->itt = build_itt(mtask->itt, conn->id, 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))
+                    !(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
+                        session->queued_cmdsn++;
                         session->cmdsn++;
+                }
         }
 
         if (session->tt->init_mgmt_task)
@@ -641,9 +648,11 @@ static int iscsi_check_cmdsn_window_closed(struct iscsi_conn *conn)
         /*
          * Check for iSCSI window and take care of CmdSN wrap-around
          */
-        if (!iscsi_sna_lte(session->cmdsn, session->max_cmdsn)) {
-                debug_scsi("iSCSI CmdSN closed. MaxCmdSN %u CmdSN %u\n",
-                           session->max_cmdsn, session->cmdsn);
+        if (!iscsi_sna_lte(session->queued_cmdsn, session->max_cmdsn)) {
+                debug_scsi("iSCSI CmdSN closed. ExpCmdSn %u MaxCmdSN %u "
+                           "CmdSN %u/%u\n", session->exp_cmdsn,
+                           session->max_cmdsn, session->cmdsn,
+                           session->queued_cmdsn);
                 return -ENOSPC;
         }
         return 0;
@@ -722,11 +731,6 @@ check_mgmt:
 
         /* process command queue */
         while (!list_empty(&conn->xmitqueue)) {
-                rc = iscsi_check_cmdsn_window_closed(conn);
-                if (rc) {
-                        spin_unlock_bh(&conn->session->lock);
-                        return rc;
-                }
                 /*
                  * iscsi tcp may readd the task to the xmitqueue to send
                  * write data
@@ -834,12 +838,6 @@ int iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
                 goto fault;
         }
 
-        /*
-         * We check this here and in data xmit, because if we get to the point
-         * that this check is hitting the window then we have enough IO in
-         * flight and enough IO waiting to be transmitted it is better
-         * to let the scsi/block layer queue up.
-         */
         if (iscsi_check_cmdsn_window_closed(conn)) {
                 reason = FAILURE_WINDOW_CLOSED;
                 goto reject;
@@ -850,6 +848,8 @@ 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;
 
@@ -1140,7 +1140,13 @@ static void fail_command(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
         if (!sc)
                 return;
 
-        if (ctask->state != ISCSI_TASK_PENDING)
+        if (ctask->state == ISCSI_TASK_PENDING)
+                /*
+                 * cmd never made it to the xmit thread, so we should not count
+                 * the cmd in the sequencing
+                 */
+                conn->session->queued_cmdsn--;
+        else
                 conn->session->tt->cleanup_cmd_task(conn, ctask);
         iscsi_ctask_mtask_cleanup(ctask);
 
@@ -1392,7 +1398,7 @@ iscsi_session_setup(struct iscsi_transport *iscsit,
         session->state = ISCSI_STATE_FREE;
         session->mgmtpool_max = ISCSI_MGMT_CMDS_MAX;
         session->cmds_max = cmds_max;
-        session->cmdsn = initial_cmdsn;
+        session->queued_cmdsn = session->cmdsn = initial_cmdsn;
         session->exp_cmdsn = initial_cmdsn + 1;
         session->max_cmdsn = initial_cmdsn + 1;
         session->max_r2t = 1;
@@ -1616,11 +1622,8 @@ void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
         kfree(conn->persistent_address);
         __kfifo_put(session->mgmtpool.queue, (void*)&conn->login_mtask,
                     sizeof(void*));
-        if (session->leadconn == conn) {
+        if (session->leadconn == conn)
                 session->leadconn = NULL;
-                /* no connections exits.. reset sequencing */
-                session->cmdsn = session->max_cmdsn = session->exp_cmdsn = 1;
-        }
         spin_unlock_bh(&session->lock);
 
         kfifo_free(conn->mgmtqueue);
@@ -1650,6 +1653,7 @@ int iscsi_conn_start(struct iscsi_cls_conn *cls_conn)
         spin_lock_bh(&session->lock);
         conn->c_stage = ISCSI_CONN_STARTED;
         session->state = ISCSI_STATE_LOGGED_IN;
+        session->queued_cmdsn = session->cmdsn;
 
         switch(conn->stop_stage) {
         case STOP_CONN_RECOVER:
diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
index 3f631b08a1ab..007d442412e2 100644
--- a/include/scsi/libiscsi.h
+++ b/include/scsi/libiscsi.h
@@ -210,6 +210,9 @@ struct iscsi_session {
         uint32_t                exp_cmdsn;
         uint32_t                max_cmdsn;
 
+        /* This tracks the reqs queued into the initiator */
+        uint32_t                queued_cmdsn;
+
         /* configuration */
         int                     initial_r2t_en;
         unsigned                max_r2t;