block: mark bio_truncate static

bio_truncate is only used in bio.c, so mark it static.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211012161804.991559-9-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

block/bio.c

@@ -546,7 +546,7 @@ EXPORT_SYMBOL(zero_fill_bio);
  *   REQ_OP_READ, zero the truncated part. This function should only
  *   be used for handling corner cases, such as bio eod.
  */
-void bio_truncate(struct bio *bio, unsigned new_size)
+static void bio_truncate(struct bio *bio, unsigned new_size)
 {
 	struct bio_vec bv;
 	struct bvec_iter iter;

include/linux/bio.h

@@ -405,7 +405,6 @@ extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
 			       struct bio *src, struct bvec_iter *src_iter);
 extern void bio_copy_data(struct bio *dst, struct bio *src);
 extern void bio_free_pages(struct bio *bio);
-void bio_truncate(struct bio *bio, unsigned new_size);
 void guard_bio_eod(struct bio *bio);
 void zero_fill_bio(struct bio *bio);