block: move struct biovec_slab to bio.c

struct biovec_slab is only used inside of bio.c, so move it there.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -25,6 +25,12 @@
 #include "blk.h"
 #include "blk-rq-qos.h"
 
+struct biovec_slab {
+	int nr_vecs;
+	char *name;
+	struct kmem_cache *slab;
+};
+
 /*
  * if you change this list, also change bvec_alloc or things will
  * break badly! cannot be bigger than what you can fit into an

include/linux/bio.h

@@ -720,12 +720,6 @@ struct bio_set {
 	struct workqueue_struct	*rescue_workqueue;
 };
 
-struct biovec_slab {
-	int nr_vecs;
-	char *name;
-	struct kmem_cache *slab;
-};
-
 static inline bool bioset_initialized(struct bio_set *bs)
 {
 	return bs->bio_slab != NULL;