block: get rid of bio_rw and READA

These two are confusing leftover of the old world order, combining
values of the REQ_OP_ and REQ_ namespaces.  For callers that don't
special case we mostly just replace bi_rw with bio_data_dir or
op_is_write, except for the few cases where a switch over the REQ_OP_
values makes more sense.  Any check for READA is replaced with an
explicit check for REQ_RAHEAD.  Also remove the READA alias for
REQ_RAHEAD.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/dm-raid1.c

@@ -528,7 +528,7 @@ static void read_callback(unsigned long error, void *context)
 		DMWARN_LIMIT("Read failure on mirror device %s.  "
 			     "Trying alternative device.",
 			     m->dev->name);
-		queue_bio(m->ms, bio, bio_rw(bio));
+		queue_bio(m->ms, bio, bio_data_dir(bio));
 		return;
 	}
 
@@ -1193,7 +1193,7 @@ static void mirror_dtr(struct dm_target *ti)
  */
 static int mirror_map(struct dm_target *ti, struct bio *bio)
 {
-	int r, rw = bio_rw(bio);
+	int r, rw = bio_data_dir(bio);
 	struct mirror *m;
 	struct mirror_set *ms = ti->private;
 	struct dm_dirty_log *log = dm_rh_dirty_log(ms->rh);
@@ -1217,7 +1217,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 	 * If region is not in-sync queue the bio.
 	 */
 	if (!r || (r == -EWOULDBLOCK)) {
-		if (rw == READA)
+		if (bio->bi_rw & REQ_RAHEAD)
 			return -EWOULDBLOCK;
 
 		queue_bio(ms, bio, rw);
@@ -1242,7 +1242,7 @@ static int mirror_map(struct dm_target *ti, struct bio *bio)
 
 static int mirror_end_io(struct dm_target *ti, struct bio *bio, int error)
 {
-	int rw = bio_rw(bio);
+	int rw = bio_data_dir(bio);
 	struct mirror_set *ms = (struct mirror_set *) ti->private;
 	struct mirror *m = NULL;
 	struct dm_bio_details *bd = NULL;

drivers/md/dm-snap.c

@@ -1696,7 +1696,8 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	 * to copy an exception */
 	down_write(&s->lock);
 
-	if (!s->valid || (unlikely(s->snapshot_overflowed) && bio_rw(bio) == WRITE)) {
+	if (!s->valid || (unlikely(s->snapshot_overflowed) &&
+	    bio_data_dir(bio) == WRITE)) {
 		r = -EIO;
 		goto out_unlock;
 	}
@@ -1713,7 +1714,7 @@ static int snapshot_map(struct dm_target *ti, struct bio *bio)
 	 * flags so we should only get this if we are
 	 * writeable.
 	 */
-	if (bio_rw(bio) == WRITE) {
+	if (bio_data_dir(bio) == WRITE) {
 		pe = __lookup_pending_exception(s, chunk);
 		if (!pe) {
 			up_write(&s->lock);
@@ -1819,7 +1820,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio)
 	e = dm_lookup_exception(&s->complete, chunk);
 	if (e) {
 		/* Queue writes overlapping with chunks being merged */
-		if (bio_rw(bio) == WRITE &&
+		if (bio_data_dir(bio) == WRITE &&
 		    chunk >= s->first_merging_chunk &&
 		    chunk < (s->first_merging_chunk +
 			     s->num_merging_chunks)) {
@@ -1831,7 +1832,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio)
 
 		remap_exception(s, e, bio, chunk);
 
-		if (bio_rw(bio) == WRITE)
+		if (bio_data_dir(bio) == WRITE)
 			track_chunk(s, bio, chunk);
 		goto out_unlock;
 	}
@@ -1839,7 +1840,7 @@ static int snapshot_merge_map(struct dm_target *ti, struct bio *bio)
 redirect_to_origin:
 	bio->bi_bdev = s->origin->bdev;
 
-	if (bio_rw(bio) == WRITE) {
+	if (bio_data_dir(bio) == WRITE) {
 		up_write(&s->lock);
 		return do_origin(s->origin, bio);
 	}
@@ -2288,7 +2289,7 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
 	if (unlikely(bio->bi_rw & REQ_PREFLUSH))
 		return DM_MAPIO_REMAPPED;
 
-	if (bio_rw(bio) != WRITE)
+	if (bio_data_dir(bio) != WRITE)
 		return DM_MAPIO_REMAPPED;
 
 	available_sectors = o->split_boundary -

drivers/md/dm-zero.c

@@ -35,16 +35,19 @@ static int zero_ctr(struct dm_target *ti, unsigned int argc, char **argv)
  */
 static int zero_map(struct dm_target *ti, struct bio *bio)
 {
-	switch(bio_rw(bio)) {
-	case READ:
+	switch (bio_op(bio)) {
+	case REQ_OP_READ:
+		if (bio->bi_rw & REQ_RAHEAD) {
+			/* readahead of null bytes only wastes buffer cache */
+			return -EIO;
+		}
 		zero_fill_bio(bio);
 		break;
-	case READA:
-		/* readahead of null bytes only wastes buffer cache */
-		return -EIO;
-	case WRITE:
+	case REQ_OP_WRITE:
 		/* writes get silently dropped */
 		break;
+	default:
+		return -EIO;
 	}
 
 	bio_endio(bio);

drivers/md/dm.c

@@ -1833,7 +1833,7 @@ static blk_qc_t dm_make_request(struct request_queue *q, struct bio *bio)
 	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
 		dm_put_live_table(md, srcu_idx);
 
-		if (bio_rw(bio) != READA)
+		if (!(bio->bi_rw & REQ_RAHEAD))
 			queue_io(md, bio);
 		else
 			bio_io_error(bio);

drivers/md/raid1.c

@@ -1105,7 +1105,7 @@ static void raid1_make_request(struct mddev *mddev, struct bio * bio)
 	bitmap = mddev->bitmap;
 
 	/*
-	 * make_request() can abort the operation when READA is being
+	 * make_request() can abort the operation when read-ahead is being
 	 * used and no empty request is available.
 	 *
 	 */

drivers/md/raid5.c

@@ -5233,7 +5233,7 @@ static void raid5_make_request(struct mddev *mddev, struct bio * bi)
 			(unsigned long long)logical_sector);
 
 		sh = raid5_get_active_stripe(conf, new_sector, previous,
-				       (bi->bi_rw&RWA_MASK), 0);
+				       (bi->bi_rw & REQ_RAHEAD), 0);
 		if (sh) {
 			if (unlikely(previous)) {
 				/* expansion might have moved on while waiting for a