target: pass sense_reason as a return value

Pass the sense reason as an explicit return value from the I/O submission
path instead of storing it in struct se_cmd and using negative return
values.  This cleans up a lot of the code pathes, and with the sparse
annotations for the new sense_reason_t type allows for much better
error checking.

(nab: Convert spc_emulate_modesense + spc_emulate_modeselect to use
      sense_reason_t with Roland's MODE SELECT changes)

Signed-off-by: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

3 files changed, 34 insertions, 59 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 035c2c762537..093fb6010272 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -767,9 +767,8 @@ static int iscsit_handle_scsi_cmd(
         struct iscsi_conn *conn,
         unsigned char *buf)
 {
-        int     data_direction, cmdsn_ret = 0, immed_ret, ret, transport_ret;
-        int     dump_immediate_data = 0, send_check_condition = 0, payload_length;
-        struct iscsi_cmd        *cmd = NULL;
+        int data_direction, payload_length, cmdsn_ret = 0, immed_ret;
+        struct iscsi_cmd *cmd = NULL;
         struct iscsi_scsi_req *hdr;
         int iscsi_task_attr;
         int sam_task_attr;
@@ -956,38 +955,26 @@ done:
                 " ExpXferLen: %u, Length: %u, CID: %hu\n", hdr->itt,
                 hdr->cmdsn, hdr->data_length, payload_length, conn->cid);
 
-        /*
-         * The CDB is going to an se_device_t.
-         */
-        ret = transport_lookup_cmd_lun(&cmd->se_cmd,
-                                       scsilun_to_int(&hdr->lun));
-        if (ret < 0) {
-                if (cmd->se_cmd.scsi_sense_reason == TCM_NON_EXISTENT_LUN) {
-                        pr_debug("Responding to non-acl'ed,"
-                                " non-existent or non-exported iSCSI LUN:"
-                                " 0x%016Lx\n", get_unaligned_le64(&hdr->lun));
+        cmd->sense_reason = transport_lookup_cmd_lun(&cmd->se_cmd,
+                                                     scsilun_to_int(&hdr->lun));
+        if (cmd->sense_reason)
+                goto attach_cmd;
+
+        cmd->sense_reason = target_setup_cmd_from_cdb(&cmd->se_cmd, hdr->cdb);
+        if (cmd->sense_reason) {
+                if (cmd->sense_reason == TCM_OUT_OF_RESOURCES) {
+                        return iscsit_add_reject_from_cmd(
+                                        ISCSI_REASON_BOOKMARK_NO_RESOURCES,
+                                        1, 1, buf, cmd);
                 }
-                send_check_condition = 1;
+
                 goto attach_cmd;
         }
 
-        transport_ret = target_setup_cmd_from_cdb(&cmd->se_cmd, hdr->cdb);
-        if (transport_ret == -ENOMEM) {
+        if (iscsit_build_pdu_and_seq_lists(cmd, payload_length) < 0) {
                 return iscsit_add_reject_from_cmd(
-                                ISCSI_REASON_BOOKMARK_NO_RESOURCES,
-                                1, 1, buf, cmd);
-        } else if (transport_ret < 0) {
-                /*
-                 * Unsupported SAM Opcode.  CHECK_CONDITION will be sent
-                 * in iscsit_execute_cmd() during the CmdSN OOO Execution
-                 * Mechinism.
-                 */
-                send_check_condition = 1;
-        } else {
-                if (iscsit_build_pdu_and_seq_lists(cmd, payload_length) < 0)
-                        return iscsit_add_reject_from_cmd(
-                                ISCSI_REASON_BOOKMARK_NO_RESOURCES,
-                                1, 1, buf, cmd);
+                        ISCSI_REASON_BOOKMARK_NO_RESOURCES,
+                        1, 1, buf, cmd);
         }
 
 attach_cmd:
@@ -1000,11 +987,12 @@ attach_cmd:
          */
         core_alua_check_nonop_delay(&cmd->se_cmd);
 
-        ret = iscsit_allocate_iovecs(cmd);
-        if (ret < 0)
+        if (iscsit_allocate_iovecs(cmd) < 0) {
                 return iscsit_add_reject_from_cmd(
                                 ISCSI_REASON_BOOKMARK_NO_RESOURCES,
                                 1, 0, buf, cmd);
+        }
+
         /*
          * Check the CmdSN against ExpCmdSN/MaxCmdSN here if
          * the Immediate Bit is not set, and no Immediate
@@ -1031,10 +1019,7 @@ attach_cmd:
          * If no Immediate Data is attached, it's OK to return now.
          */
         if (!cmd->immediate_data) {
-                if (send_check_condition)
-                        return 0;
-
-                if (cmd->unsolicited_data) {
+                if (!cmd->sense_reason && cmd->unsolicited_data) {
                         iscsit_set_dataout_sequence_values(cmd);
 
                         spin_lock_bh(&cmd->dataout_timeout_lock);
@@ -1050,19 +1035,17 @@ attach_cmd:
          * thread.  They are processed in CmdSN order by
          * iscsit_check_received_cmdsn() below.
          */
-        if (send_check_condition) {
+        if (cmd->sense_reason) {
                 immed_ret = IMMEDIATE_DATA_NORMAL_OPERATION;
-                dump_immediate_data = 1;
                 goto after_immediate_data;
         }
         /*
          * Call directly into transport_generic_new_cmd() to perform
          * the backend memory allocation.
          */
-        ret = transport_generic_new_cmd(&cmd->se_cmd);
-        if (ret < 0) {
+        cmd->sense_reason = transport_generic_new_cmd(&cmd->se_cmd);
+        if (cmd->sense_reason) {
                 immed_ret = IMMEDIATE_DATA_NORMAL_OPERATION;
-                dump_immediate_data = 1;
                 goto after_immediate_data;
         }
 
@@ -1079,7 +1062,7 @@ after_immediate_data:
                  * Special case for Unsupported SAM WRITE Opcodes
                  * and ImmediateData=Yes.
                  */
-                if (dump_immediate_data) {
+                if (cmd->sense_reason) {
                         if (iscsit_dump_data_payload(conn, payload_length, 1) < 0)
                                 return -1;
                 } else if (cmd->unsolicited_data) {
@@ -1272,8 +1255,7 @@ static int iscsit_handle_data_out(struct iscsi_conn *conn, unsigned char *buf)
                 spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
 
                 spin_lock_irqsave(&se_cmd->t_state_lock, flags);
-                if (!(se_cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE) ||
-                     (se_cmd->se_cmd_flags & SCF_SCSI_CDB_EXCEPTION))
+                if (!(se_cmd->se_cmd_flags & SCF_SUPPORTED_SAM_OPCODE))
                         dump_unsolicited_data = 1;
                 spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);
 
@@ -1742,7 +1724,6 @@ static int iscsit_handle_task_mgt_cmd(
                 ret = transport_lookup_tmr_lun(&cmd->se_cmd,
                                                scsilun_to_int(&hdr->lun));
                 if (ret < 0) {
-                        cmd->se_cmd.se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                         se_tmr->response = ISCSI_TMF_RSP_NO_LUN;
                         goto attach;
                 }
@@ -1751,10 +1732,8 @@ static int iscsit_handle_task_mgt_cmd(
         switch (function) {
         case ISCSI_TM_FUNC_ABORT_TASK:
                 se_tmr->response = iscsit_tmr_abort_task(cmd, buf);
-                if (se_tmr->response != ISCSI_TMF_RSP_COMPLETE) {
-                        cmd->se_cmd.se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
+                if (se_tmr->response)
                         goto attach;
-                }
                 break;
         case ISCSI_TM_FUNC_ABORT_TASK_SET:
         case ISCSI_TM_FUNC_CLEAR_ACA:
@@ -1763,14 +1742,12 @@ static int iscsit_handle_task_mgt_cmd(
                 break;
         case ISCSI_TM_FUNC_TARGET_WARM_RESET:
                 if (iscsit_tmr_task_warm_reset(conn, tmr_req, buf) < 0) {
-                        cmd->se_cmd.se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                         se_tmr->response = ISCSI_TMF_RSP_AUTH_FAILED;
                         goto attach;
                 }
                 break;
         case ISCSI_TM_FUNC_TARGET_COLD_RESET:
                 if (iscsit_tmr_task_cold_reset(conn, tmr_req, buf) < 0) {
-                        cmd->se_cmd.se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                         se_tmr->response = ISCSI_TMF_RSP_AUTH_FAILED;
                         goto attach;
                 }
@@ -1781,7 +1758,7 @@ static int iscsit_handle_task_mgt_cmd(
                  * Perform sanity checks on the ExpDataSN only if the
                  * TASK_REASSIGN was successful.
                  */
-                if (se_tmr->response != ISCSI_TMF_RSP_COMPLETE)
+                if (se_tmr->response)
                         break;
 
                 if (iscsit_check_task_reassign_expdatasn(tmr_req, conn) < 0)
@@ -1792,7 +1769,6 @@ static int iscsit_handle_task_mgt_cmd(
         default:
                 pr_err("Unknown TMR function: 0x%02x, protocol"
                         " error.\n", function);
-                cmd->se_cmd.se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
                 se_tmr->response = ISCSI_TMF_RSP_NOT_SUPPORTED;
                 goto attach;
         }
diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
index 21048dbf7d13..7a333d28d9a2 100644
--- a/drivers/target/iscsi/iscsi_target_core.h
+++ b/drivers/target/iscsi/iscsi_target_core.h
@@ -474,7 +474,7 @@ struct iscsi_cmd {
         struct scatterlist      *first_data_sg;
         u32                     first_data_sg_off;
         u32                     kmapped_nents;
-
+        sense_reason_t          sense_reason;
 }  ____cacheline_aligned;
 
 struct iscsi_tmr_req {
diff --git a/drivers/target/iscsi/iscsi_target_erl1.c b/drivers/target/iscsi/iscsi_target_erl1.c
index 21f29d91a8cb..0b52a2371305 100644
--- a/drivers/target/iscsi/iscsi_target_erl1.c
+++ b/drivers/target/iscsi/iscsi_target_erl1.c
@@ -929,11 +929,10 @@ int iscsit_execute_cmd(struct iscsi_cmd *cmd, int ooo)
         case ISCSI_OP_SCSI_CMD:
                 /*
                  * Go ahead and send the CHECK_CONDITION status for
-                 * any SCSI CDB exceptions that may have occurred, also
-                 * handle the SCF_SCSI_RESERVATION_CONFLICT case here as well.
+                 * any SCSI CDB exceptions that may have occurred.
                  */
-                if (se_cmd->se_cmd_flags & SCF_SCSI_CDB_EXCEPTION) {
-                        if (se_cmd->scsi_sense_reason == TCM_RESERVATION_CONFLICT) {
+                if (cmd->sense_reason) {
+                        if (cmd->sense_reason == TCM_RESERVATION_CONFLICT) {
                                 cmd->i_state = ISTATE_SEND_STATUS;
                                 spin_unlock_bh(&cmd->istate_lock);
                                 iscsit_add_cmd_to_response_queue(cmd, cmd->conn,
@@ -956,7 +955,7 @@ int iscsit_execute_cmd(struct iscsi_cmd *cmd, int ooo)
                          * exception
                          */
                         return transport_send_check_condition_and_sense(se_cmd,
-                                        se_cmd->scsi_sense_reason, 0);
+                                        cmd->sense_reason, 0);
                 }
                 /*
                  * Special case for delayed CmdSN with Immediate
@@ -1013,7 +1012,7 @@ int iscsit_execute_cmd(struct iscsi_cmd *cmd, int ooo)
                 iscsit_add_cmd_to_response_queue(cmd, cmd->conn, cmd->i_state);
                 break;
         case ISCSI_OP_SCSI_TMFUNC:
-                if (se_cmd->se_cmd_flags & SCF_SCSI_CDB_EXCEPTION) {
+                if (cmd->se_cmd.se_tmr_req->response) {
                         spin_unlock_bh(&cmd->istate_lock);
                         iscsit_add_cmd_to_response_queue(cmd, cmd->conn,
                                         cmd->i_state);