target: Simplify fabric sense data length handling

Every fabric driver has to supply a se_tfo->set_fabric_sense_len()
method, just so iSCSI can return an offset of 2.  However, every fabric
driver is already allocating a sense buffer and passing it into the
target core, either via transport_init_se_cmd() or target_submit_cmd().

So instead of having iSCSI pass the start of its sense buffer into the
core and then later tell the core to skip the first 2 bytes, it seems
easier for iSCSI just to do the offset of 2 when it passes the sense
buffer into the core.  Then we can drop the se_tfo->set_fabric_sense_len()
everywhere, and just add a couple of lines of code to iSCSI to set the
sense data length to the beginning of the buffer right before it sends
it over the network.

(nab: Remove .set_fabric_sense_len usage from tcm_qla2xxx_npiv_ops +
      change transport_get_sense_buffer to follow v3.6-rc6 code w/o
      ->set_fabric_sense_len usage)

Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

2 files changed, 8 insertions, 21 deletions

diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 97c0f78c3c9c..9cfdeedaadb6 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -953,7 +953,7 @@ done:
          */
         transport_init_se_cmd(&cmd->se_cmd, &lio_target_fabric_configfs->tf_ops,
                         conn->sess->se_sess, hdr->data_length, cmd->data_direction,
-                        sam_task_attr, &cmd->sense_buffer[0]);
+                        sam_task_attr, cmd->sense_buffer + 2);
 
         pr_debug("Got SCSI Command, ITT: 0x%08x, CmdSN: 0x%08x,"
                 " ExpXferLen: %u, Length: %u, CID: %hu\n", hdr->itt,
@@ -1700,7 +1700,7 @@ static int iscsit_handle_task_mgt_cmd(
                 transport_init_se_cmd(&cmd->se_cmd,
                                       &lio_target_fabric_configfs->tf_ops,
                                       conn->sess->se_sess, 0, DMA_NONE,
-                                      MSG_SIMPLE_TAG, &cmd->sense_buffer[0]);
+                                      MSG_SIMPLE_TAG, cmd->sense_buffer + 2);
 
                 switch (function) {
                 case ISCSI_TM_FUNC_ABORT_TASK:
@@ -3092,15 +3092,18 @@ static int iscsit_send_status(
         if (cmd->se_cmd.sense_buffer &&
            ((cmd->se_cmd.se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
             (cmd->se_cmd.se_cmd_flags & SCF_EMULATED_TASK_SENSE))) {
+                put_unaligned_be16(cmd->se_cmd.scsi_sense_length, cmd->sense_buffer);
+                cmd->se_cmd.scsi_sense_length += sizeof (__be16);
+
                 padding         = -(cmd->se_cmd.scsi_sense_length) & 3;
                 hton24(hdr->dlength, cmd->se_cmd.scsi_sense_length);
-                iov[iov_count].iov_base = cmd->se_cmd.sense_buffer;
+                iov[iov_count].iov_base = cmd->sense_buffer;
                 iov[iov_count++].iov_len =
                                 (cmd->se_cmd.scsi_sense_length + padding);
                 tx_size += cmd->se_cmd.scsi_sense_length;
 
                 if (padding) {
-                        memset(cmd->se_cmd.sense_buffer +
+                        memset(cmd->sense_buffer +
                                 cmd->se_cmd.scsi_sense_length, 0, padding);
                         tx_size += padding;
                         pr_debug("Adding %u bytes of padding to"
@@ -3109,7 +3112,7 @@ static int iscsit_send_status(
 
                 if (conn->conn_ops->DataDigest) {
                         iscsit_do_crypto_hash_buf(&conn->conn_tx_hash,
-                                cmd->se_cmd.sense_buffer,
+                                cmd->sense_buffer,
                                 (cmd->se_cmd.scsi_sense_length + padding),
                                 0, NULL, (u8 *)&cmd->data_crc);
 
diff --git a/drivers/target/iscsi/iscsi_target_configfs.c b/drivers/target/iscsi/iscsi_target_configfs.c
index 518fd4e86409..f86833fcf33c 100644
--- a/drivers/target/iscsi/iscsi_target_configfs.c
+++ b/drivers/target/iscsi/iscsi_target_configfs.c
@@ -1542,21 +1542,6 @@ static int lio_queue_status(struct se_cmd *se_cmd)
         return 0;
 }
 
-static u16 lio_set_fabric_sense_len(struct se_cmd *se_cmd, u32 sense_length)
-{
-        unsigned char *buffer = se_cmd->sense_buffer;
-        /*
-         * From RFC-3720 10.4.7.  Data Segment - Sense and Response Data Segment
-         * 16-bit SenseLength.
-         */
-        buffer[0] = ((sense_length >> 8) & 0xff);
-        buffer[1] = (sense_length & 0xff);
-        /*
-         * Return two byte offset into allocated sense_buffer.
-         */
-        return 2;
-}
-
 static int lio_queue_tm_rsp(struct se_cmd *se_cmd)
 {
         struct iscsi_cmd *cmd = container_of(se_cmd, struct iscsi_cmd, se_cmd);
@@ -1740,7 +1725,6 @@ int iscsi_target_register_configfs(void)
         fabric->tf_ops.queue_data_in = &lio_queue_data_in;
         fabric->tf_ops.queue_status = &lio_queue_status;
         fabric->tf_ops.queue_tm_rsp = &lio_queue_tm_rsp;
-        fabric->tf_ops.set_fabric_sense_len = &lio_set_fabric_sense_len;
         /*
          * Setup function pointers for generic logic in target_core_fabric_configfs.c
          */