btrfs: update __btrfs_map_block for REQ_OP transition

We no longer pass in a bitmap of rq_flag_bits bits to __btrfs_map_block.
It will always be a REQ_OP, or the btrfs specific REQ_GET_READ_MIRRORS,
so this drops the bit tests.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 0ac90f8..3b78700 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -375,10 +375,10 @@
 				   u64 end, u64 *length);
 void btrfs_get_bbio(struct btrfs_bio *bbio);
 void btrfs_put_bbio(struct btrfs_bio *bbio);
-int btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
+int btrfs_map_block(struct btrfs_fs_info *fs_info, int op,
 		    u64 logical, u64 *length,
 		    struct btrfs_bio **bbio_ret, int mirror_num);
-int btrfs_map_sblock(struct btrfs_fs_info *fs_info, int rw,
+int btrfs_map_sblock(struct btrfs_fs_info *fs_info, int op,
 		     u64 logical, u64 *length,
 		     struct btrfs_bio **bbio_ret, int mirror_num,
 		     int need_raid_map);