block: mark bio_add_folio as __must_check

Now that all callers of bio_add_folio() check the return value, mark it as
__must_check.
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/381360a45ac3684120cfbe1e07685e9c36256e47.1685532726.git.johannes.thumshirn@wdc.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/bio.h

@@ -467,7 +467,8 @@ void bio_chain(struct bio *, struct bio *);
 
 int __must_check bio_add_page(struct bio *bio, struct page *page, unsigned len,
 			      unsigned off);
-bool bio_add_folio(struct bio *, struct folio *, size_t len, size_t off);
+bool __must_check bio_add_folio(struct bio *bio, struct folio *folio,
+				size_t len, size_t off);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
 int bio_add_zone_append_page(struct bio *bio, struct page *page,