IB/srp: Support SRP rev. 10 targets

There has been a change in the format of port identifiers between
revision 10 of the SRP specification and the current revision 16A.

Revision 10 specifies port identifier format as

  lower 8 bytes :  GUID   upper 8 bytes :  Extension

Whereas revision 16A specifies it as 

 lower 8 bytes :  Extension  upper 8 bytes :  GUID

There are older targets (e.g. SilverStorm Virtual Fibre Channel
Bridge) which conform to revision 10 of the SRP specification.

The I/O class of revision 10 is 0xFF00 and the I/O class of revision
16A is 0x0100.

For supporting older targets, this patch:

1) Adds a new optional target creation parameter "io_class". Default
   value of io_class is 0x0100 (i.e. revision 16A)
2) Uses the correct port identifier format for targets with IO class
   of 0xFF00 (i.e. conforming to revision 10)

Signed-off-by: Ramachandra K <rkuchimanchi@silverstorm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

2 files changed, 42 insertions, 3 deletions

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index f1401e1f2f97..e7fa8b680cb6 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -321,7 +321,29 @@ static int srp_send_req(struct srp_target_port *target)
         req->priv.req_it_iu_len = cpu_to_be32(srp_max_iu_len);
         req->priv.req_buf_fmt   = cpu_to_be16(SRP_BUF_FORMAT_DIRECT |
                                               SRP_BUF_FORMAT_INDIRECT);
-        memcpy(req->priv.initiator_port_id, target->srp_host->initiator_port_id, 16);
+        /*
+         * In the published SRP specification (draft rev. 16a), the 
+         * port identifier format is 8 bytes of ID extension followed
+         * by 8 bytes of GUID.  Older drafts put the two halves in the
+         * opposite order, so that the GUID comes first.
+         *
+         * Targets conforming to these obsolete drafts can be
+         * recognized by the I/O Class they report.
+         */
+        if (target->io_class == SRP_REV10_IB_IO_CLASS) {
+                memcpy(req->priv.initiator_port_id,
+                       target->srp_host->initiator_port_id + 8, 8);
+                memcpy(req->priv.initiator_port_id + 8,
+                       target->srp_host->initiator_port_id, 8);
+                memcpy(req->priv.target_port_id,     &target->ioc_guid, 8);
+                memcpy(req->priv.target_port_id + 8, &target->id_ext, 8);
+        } else {
+                memcpy(req->priv.initiator_port_id,
+                       target->srp_host->initiator_port_id, 16);
+                memcpy(req->priv.target_port_id,     &target->id_ext, 8);
+                memcpy(req->priv.target_port_id + 8, &target->ioc_guid, 8);
+        }
+
         /*
          * Topspin/Cisco SRP targets will reject our login unless we
          * zero out the first 8 bytes of our initiator port ID.  The
@@ -334,8 +356,6 @@ static int srp_send_req(struct srp_target_port *target)
                        (unsigned long long) be64_to_cpu(target->ioc_guid));
                 memset(req->priv.initiator_port_id, 0, 8);
         }
-        memcpy(req->priv.target_port_id,     &target->id_ext, 8);
-        memcpy(req->priv.target_port_id + 8, &target->ioc_guid, 8);
 
         status = ib_send_cm_req(target->cm_id, &req->param);
 
@@ -1511,6 +1531,7 @@ enum {
         SRP_OPT_SERVICE_ID      = 1 << 4,
         SRP_OPT_MAX_SECT        = 1 << 5,
         SRP_OPT_MAX_CMD_PER_LUN = 1 << 6,
+        SRP_OPT_IO_CLASS        = 1 << 7,
         SRP_OPT_ALL             = (SRP_OPT_ID_EXT       |
                                    SRP_OPT_IOC_GUID     |
                                    SRP_OPT_DGID         |
@@ -1526,6 +1547,7 @@ static match_table_t srp_opt_tokens = {
         { SRP_OPT_SERVICE_ID,           "service_id=%s"         },
         { SRP_OPT_MAX_SECT,             "max_sect=%d"           },
         { SRP_OPT_MAX_CMD_PER_LUN,      "max_cmd_per_lun=%d"    },
+        { SRP_OPT_IO_CLASS,             "io_class=%x"           },
         { SRP_OPT_ERR,                  NULL                    }
 };
 
@@ -1610,6 +1632,21 @@ static int srp_parse_options(const char *buf, struct srp_target_port *target)
                         target->scsi_host->cmd_per_lun = min(token, SRP_SQ_SIZE);
                         break;
 
+                case SRP_OPT_IO_CLASS:
+                        if (match_hex(args, &token)) {
+                                printk(KERN_WARNING PFX "bad  IO class parameter '%s' \n", p);
+                                goto out;
+                        }
+                        if (token != SRP_REV10_IB_IO_CLASS &&
+                            token != SRP_REV16A_IB_IO_CLASS) {
+                                printk(KERN_WARNING PFX "unknown IO class parameter value"
+                                       " %x specified (use %x or %x).\n",
+                                       token, SRP_REV10_IB_IO_CLASS, SRP_REV16A_IB_IO_CLASS);
+                                goto out;
+                        }
+                        target->io_class = token;
+                        break;
+
                 default:
                         printk(KERN_WARNING PFX "unknown parameter or missing value "
                                "'%s' in target creation request\n", p);
@@ -1652,6 +1689,7 @@ static ssize_t srp_create_target(struct class_device *class_dev,
         target = host_to_target(target_host);
         memset(target, 0, sizeof *target);
 
+        target->io_class   = SRP_REV16A_IB_IO_CLASS;
         target->scsi_host  = target_host;
         target->srp_host   = host;
 
diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h
index ad45e4856e1c..5b581fb8eb0d 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.h
+++ b/drivers/infiniband/ulp/srp/ib_srp.h
@@ -122,6 +122,7 @@ struct srp_target_port {
         __be64                  id_ext;
         __be64                  ioc_guid;
         __be64                  service_id;
+        u16                     io_class;
         struct srp_host        *srp_host;
         struct Scsi_Host       *scsi_host;
         char                    target_name[32];