target: add support for START_STOP_UNIT SCSI opcode

AIX servers using VIOS servers that virtualize FC cards will have a
problem booting without support for START_STOP_UNIT.

Cite sbc3r36 exactly, clean up if conditions (rob + hch)

Signed-off-by: Brian Bunker <brian@purestorage.com>
Signed-off-by: Spencer Baugh <sbaugh@catern.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: "Robert Elliott (Server Storage)" <Elliott@hp.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index ac7215039e5a79420cb5b7bcbdfc14ba98409fbd..4fc8343786f2b94302f9530f5f1514208e9d0fc7 100644 (file)
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -154,6 +154,38 @@ sbc_emulate_readcapacity_16(struct se_cmd *cmd)
        return 0;
 }
 
+static sense_reason_t
+sbc_emulate_startstop(struct se_cmd *cmd)
+{
+       unsigned char *cdb = cmd->t_task_cdb;
+
+       /*
+        * See sbc3r36 section 5.25
+        * Immediate bit should be set since there is nothing to complete
+        * POWER CONDITION MODIFIER 0h
+        */
+       if (!(cdb[1] & 1) || cdb[2] || cdb[3])
+               return TCM_INVALID_CDB_FIELD;
+
+       /*
+        * See sbc3r36 section 5.25
+        * POWER CONDITION 0h START_VALID - process START and LOEJ
+        */
+       if (cdb[4] >> 4 & 0xf)
+               return TCM_INVALID_CDB_FIELD;
+
+       /*
+        * See sbc3r36 section 5.25
+        * LOEJ 0h - nothing to load or unload
+        * START 1h - we are ready
+        */
+       if (!(cdb[4] & 1) || (cdb[4] & 2) || (cdb[4] & 4))
+               return TCM_INVALID_CDB_FIELD;
+
+       target_complete_cmd(cmd, SAM_STAT_GOOD);
+       return 0;
+}
+
 sector_t sbc_get_write_same_sectors(struct se_cmd *cmd)
 {
        u32 num_blocks;
@@ -1069,6 +1101,10 @@ sbc_parse_cdb(struct se_cmd *cmd, struct sbc_ops *ops)
                size = 0;
                cmd->execute_cmd = sbc_emulate_noop;
                break;
+       case START_STOP:
+               size = 0;
+               cmd->execute_cmd = sbc_emulate_startstop;
+               break;
        default:
                ret = spc_parse_cdb(cmd, &size);
                if (ret)