target: Merge sbc_verify_dif_read|write

Instead of providing DIF verify routines for read/write
that are almost identical and conditionally copy protection
information, just let the caller do the right thing.

Have a single sbc_dif_verify that handles an sgl (that
does NOT copy any data) and a protection information copy
routine used by rd_mcp and fileio backend.

In the WRITE case, call sbc_dif_verify with cmd->t_prot_sg
and then do the copy from it to local sgl (assuming the verify
succeeded of course). In the READ case, call sbc_dif_verify
with the local sgl and if it succeeds, copy it to t_prot_sg (or
not if we are stripping it).

(Fix apply breakage from commit c836777 - nab)

Tested-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 675f2d9..105f4fd 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1766,8 +1766,8 @@
 			break;
 
 		sectors = cmd->data_length >> ilog2(cmd->se_dev->dev_attrib.block_size);
-		cmd->pi_err = sbc_dif_verify_write(cmd, cmd->t_task_lba,
-						   sectors, 0, NULL, 0);
+		cmd->pi_err = sbc_dif_verify(cmd, cmd->t_task_lba,
+					     sectors, 0, cmd->t_prot_sg, 0);
 		if (unlikely(cmd->pi_err)) {
 			spin_lock_irq(&cmd->t_state_lock);
 			cmd->transport_state &= ~(CMD_T_BUSY|CMD_T_SENT);
@@ -1991,16 +1991,17 @@
 
 static bool target_read_prot_action(struct se_cmd *cmd)
 {
-	sense_reason_t rc;
-
 	switch (cmd->prot_op) {
 	case TARGET_PROT_DIN_STRIP:
 		if (!(cmd->se_sess->sup_prot_ops & TARGET_PROT_DIN_STRIP)) {
-			rc = sbc_dif_read_strip(cmd);
-			if (rc) {
-				cmd->pi_err = rc;
+			u32 sectors = cmd->data_length >>
+				  ilog2(cmd->se_dev->dev_attrib.block_size);
+
+			cmd->pi_err = sbc_dif_verify(cmd, cmd->t_task_lba,
+						     sectors, 0, cmd->t_prot_sg,
+						     0);
+			if (cmd->pi_err)
 				return true;
-			}
 		}
 		break;
 	case TARGET_PROT_DIN_INSERT: