block: move the BIO_CLONED checks out of __bio_try_merge_page

__bio_try_merge_page is a way too low-level helper to assert that the
bio is not cloned.  Move the check into bio_add_page and
bio_iov_iter_get_pages instead, which are the high level entry points
that should enforce this variant.  bio_add_hw_page already this
check, coverig the third (indirect) caller of __bio_try_merge_page.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jinyoung Choi <j-young.choi@samsung.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20230724165433.117645-4-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -945,9 +945,6 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
 static bool __bio_try_merge_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off, bool *same_page)
 {
-	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
-		return false;
-
 	if (bio->bi_vcnt > 0) {
 		struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
 
@@ -1127,6 +1124,9 @@ int bio_add_page(struct bio *bio, struct page *page,
 {
 	bool same_page = false;
 
+	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+		return 0;
+
 	if (!__bio_try_merge_page(bio, page, len, offset, &same_page)) {
 		if (bio_full(bio, len))
 			return 0;
@@ -1335,6 +1335,9 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
 	int ret = 0;
 
+	if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED)))
+		return -EIO;
+
 	if (iov_iter_is_bvec(iter)) {
 		bio_iov_bvec_set(bio, iter);
 		iov_iter_advance(iter, bio->bi_iter.bi_size);