blk_end_request: add/export functions to get request size (take 4)

This patch adds/exports functions to get the size of request in bytes.
They are useful because blk_end_request interfaces take bytes
as a completed I/O size instead of sectors.

Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 3b212f0..aa2341d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -737,6 +737,14 @@
 extern void blk_complete_request(struct request *);
 
 /*
+ * blk_end_request() takes bytes instead of sectors as a complete size.
+ * blk_rq_bytes() returns bytes left to complete in the entire request.
+ * blk_rq_cur_bytes() returns bytes left to complete in the current segment.
+ */
+extern unsigned int blk_rq_bytes(struct request *rq);
+extern unsigned int blk_rq_cur_bytes(struct request *rq);
+
+/*
  * end_that_request_first/chunk() takes an uptodate argument. we account
  * any value <= as an io error. 0 means -EIO for compatability reasons,
  * any other < 0 value is the direct error type. An uptodate value of