block: unify flags for struct bio and struct request

Remove the current bio flags and reuse the request flags for the bio, too.
This allows to more easily trace the type of I/O from the filesystem
down to the block driver.  There were two flags in the bio that were
missing in the requests:  BIO_RW_UNPLUG and BIO_RW_AHEAD.  Also I've
renamed two request flags that had a superflous RW in them.

Note that the flags are in bio.h despite having the REQ_ name - as
blkdev.h includes bio.h that is the only way to go for now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index d4edeb8..eb4086f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -458,7 +458,7 @@
  */
 static inline bool cfq_bio_sync(struct bio *bio)
 {
-	return bio_data_dir(bio) == READ || bio_rw_flagged(bio, BIO_RW_SYNCIO);
+	return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC);
 }
 
 /*
@@ -646,10 +646,10 @@
 		return rq1;
 	else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
 		return rq2;
-	if ((rq1->cmd_flags & REQ_RW_META) && !(rq2->cmd_flags & REQ_RW_META))
+	if ((rq1->cmd_flags & REQ_META) && !(rq2->cmd_flags & REQ_META))
 		return rq1;
-	else if ((rq2->cmd_flags & REQ_RW_META) &&
-		 !(rq1->cmd_flags & REQ_RW_META))
+	else if ((rq2->cmd_flags & REQ_META) &&
+		 !(rq1->cmd_flags & REQ_META))
 		return rq2;
 
 	s1 = blk_rq_pos(rq1);
@@ -1485,7 +1485,7 @@
 	cfqq->cfqd->rq_queued--;
 	cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
 					rq_data_dir(rq), rq_is_sync(rq));
-	if (rq->cmd_flags & REQ_RW_META) {
+	if (rq->cmd_flags & REQ_META) {
 		WARN_ON(!cfqq->meta_pending);
 		cfqq->meta_pending--;
 	}
@@ -3177,7 +3177,7 @@
 	 * So both queues are sync. Let the new request get disk time if
 	 * it's a metadata request and the current queue is doing regular IO.
 	 */
-	if ((rq->cmd_flags & REQ_RW_META) && !cfqq->meta_pending)
+	if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
 		return true;
 
 	/*
@@ -3231,7 +3231,7 @@
 	struct cfq_io_context *cic = RQ_CIC(rq);
 
 	cfqd->rq_queued++;
-	if (rq->cmd_flags & REQ_RW_META)
+	if (rq->cmd_flags & REQ_META)
 		cfqq->meta_pending++;
 
 	cfq_update_io_thinktime(cfqd, cic);