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>

1 files changed, 24 insertions, 27 deletions

diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index aa3e80a2f8db..b5c722bdd993 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -60,7 +60,7 @@ static inline struct pscsi_dev_virt *PSCSI_DEV(struct se_device *dev)
 
 static struct se_subsystem_api pscsi_template;
 
-static int pscsi_execute_cmd(struct se_cmd *cmd);
+static sense_reason_t pscsi_execute_cmd(struct se_cmd *cmd);
 static void pscsi_req_done(struct request *, int);
 
 /*      pscsi_attach_hba():
@@ -642,7 +642,11 @@ static void pscsi_transport_complete(struct se_cmd *cmd, struct scatterlist *sg,
         if (((cdb[0] == MODE_SENSE) || (cdb[0] == MODE_SENSE_10)) &&
              (status_byte(result) << 1) == SAM_STAT_GOOD) {
                 if (cmd->se_deve->lun_flags & TRANSPORT_LUNFLAGS_READ_ONLY) {
-                        unsigned char *buf = transport_kmap_data_sg(cmd);
+                        unsigned char *buf;
+
+                        buf = transport_kmap_data_sg(cmd);
+                        if (!buf)
+                                ; /* XXX: TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE */
 
                         if (cdb[0] == MODE_SENSE_10) {
                                 if (!(buf[3] & 0x80))
@@ -856,9 +860,9 @@ static inline struct bio *pscsi_get_bio(int sg_num)
         return bio;
 }
 
-static int pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl,
-                u32 sgl_nents, enum dma_data_direction data_direction,
-                struct bio **hbio)
+static sense_reason_t
+pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
+                enum dma_data_direction data_direction, struct bio **hbio)
 {
         struct pscsi_dev_virt *pdv = PSCSI_DEV(cmd->se_dev);
         struct bio *bio = NULL, *tbio = NULL;
@@ -946,7 +950,7 @@ static int pscsi_map_sg(struct se_cmd *cmd, struct scatterlist *sgl,
                 }
         }
 
-        return sgl_nents;
+        return 0;
 fail:
         while (*hbio) {
                 bio = *hbio;
@@ -954,8 +958,7 @@ fail:
                 bio->bi_next = NULL;
                 bio_endio(bio, 0);      /* XXX: should be error */
         }
-        cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-        return -ENOMEM;
+        return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 }
 
 /*
@@ -982,15 +985,13 @@ static inline void pscsi_clear_cdb_lun(unsigned char *cdb)
         }
 }
 
-static int pscsi_parse_cdb(struct se_cmd *cmd)
+static sense_reason_t
+pscsi_parse_cdb(struct se_cmd *cmd)
 {
         unsigned char *cdb = cmd->t_task_cdb;
 
-        if (cmd->se_cmd_flags & SCF_BIDI) {
-                cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
-                cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
-                return -EINVAL;
-        }
+        if (cmd->se_cmd_flags & SCF_BIDI)
+                return TCM_UNSUPPORTED_SCSI_OPCODE;
 
         pscsi_clear_cdb_lun(cdb);
 
@@ -1020,7 +1021,8 @@ static int pscsi_parse_cdb(struct se_cmd *cmd)
         }
 }
 
-static int pscsi_execute_cmd(struct se_cmd *cmd)
+static sense_reason_t
+pscsi_execute_cmd(struct se_cmd *cmd)
 {
         struct scatterlist *sgl = cmd->t_data_sg;
         u32 sgl_nents = cmd->t_data_nents;
@@ -1029,7 +1031,7 @@ static int pscsi_execute_cmd(struct se_cmd *cmd)
         struct pscsi_plugin_task *pt;
         struct request *req;
         struct bio *hbio;
-        int ret;
+        sense_reason_t ret;
 
         /*
          * Dynamically alloc cdb space, since it may be larger than
@@ -1037,8 +1039,7 @@ static int pscsi_execute_cmd(struct se_cmd *cmd)
          */
         pt = kzalloc(sizeof(*pt) + scsi_command_size(cmd->t_task_cdb), GFP_KERNEL);
         if (!pt) {
-                cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
-                return -ENOMEM;
+                return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
         }
         cmd->priv = pt;
 
@@ -1052,24 +1053,21 @@ static int pscsi_execute_cmd(struct se_cmd *cmd)
                 if (!req || IS_ERR(req)) {
                         pr_err("PSCSI: blk_get_request() failed: %ld\n",
                                         req ? IS_ERR(req) : -ENOMEM);
-                        cmd->scsi_sense_reason =
-                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+                        ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                         goto fail;
                 }
         } else {
                 BUG_ON(!cmd->data_length);
 
                 ret = pscsi_map_sg(cmd, sgl, sgl_nents, data_direction, &hbio);
-                if (ret < 0) {
-                        cmd->scsi_sense_reason =
-                                TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+                if (ret)
                         goto fail;
-                }
 
                 req = blk_make_request(pdv->pdv_sd->request_queue, hbio,
                                        GFP_KERNEL);
                 if (IS_ERR(req)) {
                         pr_err("pSCSI: blk_make_request() failed\n");
+                        ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
                         goto fail_free_bio;
                 }
         }
@@ -1100,10 +1098,10 @@ fail_free_bio:
                 bio->bi_next = NULL;
                 bio_endio(bio, 0);      /* XXX: should be error */
         }
-        cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
+        ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 fail:
         kfree(pt);
-        return -ENOMEM;
+        return ret;
 }
 
 /*      pscsi_get_device_type():
@@ -1152,7 +1150,6 @@ static void pscsi_req_done(struct request *req, int uptodate)
                 pr_debug("PSCSI Host Byte exception at cmd: %p CDB:"
                         " 0x%02x Result: 0x%08x\n", cmd, pt->pscsi_cdb[0],
                         pt->pscsi_result);
-                cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
                 target_complete_cmd(cmd, SAM_STAT_CHECK_CONDITION);
                 break;
         }