target: Drop legacy se_cmd->check_release bit

Now with iscsi-target using modern se_cmd->cmd_kref accounting in
v3.10 code, it's safe to go ahead and drop the legacy release
codepath + se_cmd->check_release bit in transport_release_cmd()

Cc: Christoph Hellwig <hch@lst.de>
Cc: Roland Dreier <roland@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>
Cc: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Moussa Ba <moussaba@micron.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_transport.c

@@ -1952,11 +1952,7 @@ static int transport_release_cmd(struct se_cmd *cmd)
 	 * If this cmd has been setup with target_get_sess_cmd(), drop
 	 * the kref and call ->release_cmd() in kref callback.
 	 */
-	 if (cmd->check_release != 0)
-		return target_put_sess_cmd(cmd->se_sess, cmd);
-
-	cmd->se_tfo->release_cmd(cmd);
-	return 1;
+	return target_put_sess_cmd(cmd->se_sess, cmd);
 }
 
 /**
@@ -2175,8 +2171,6 @@ int target_get_sess_cmd(struct se_session *se_sess, struct se_cmd *se_cmd,
 		goto out;
 	}
 	list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
-	se_cmd->check_release = 1;
-
 out:
 	spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);
 	return ret;

include/target/target_core_base.h

@@ -420,8 +420,6 @@ struct se_cmd {
 	int			sam_task_attr;
 	/* Transport protocol dependent state, see transport_state_table */
 	enum transport_state_table t_state;
-	/* Used to signal cmd->se_tfo->check_release_cmd() usage per cmd */
-	unsigned		check_release:1;
 	unsigned		cmd_wait_set:1;
 	unsigned		unknown_data_length:1;
 	/* See se_cmd_flags_table */