[PATCH 19/32] block: add helper to get data dir from op

[mchristi@redhat.com]

From: Mike Christie <mchristi@redhat.com>

In later patches the op will no longer be a bitmap, so we will
not have REQ_WRITE set for all non reads like discard, flush,
and write same. Drivers will still want to treat them as writes
for accounting reasons, so this patch adds a helper to translate
a op to a data direction.

Signed-off-by: Mike Christie <mchristi@redhat.com>
---
 include/linux/blkdev.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 19c2e94..cf5f518 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -586,6 +586,18 @@ static inline void queue_flag_clear(unsigned int flag, struct request_queue *q)
 
 #define list_entry_rq(ptr)	list_entry((ptr), struct request, queuelist)
 
+/*
+ * Non REQ_OP_WRITE requests like discard, write same, etc, are
+ * considered WRITEs.
+ */
+static inline int op_to_data_dir(int op)
+{
+	if (op == REQ_OP_READ)
+		return READ;
+	else
+		return WRITE;
+}
+
 #define rq_data_dir(rq)		((int)((rq)->cmd_flags & 1))
 
 /*
-- 
1.8.3.1