block: refactor __bio_iov_bvec_add_pages

Return early on error, and add an unlikely annotation for that case.
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -873,7 +873,9 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
 	len = min_t(size_t, bv->bv_len - iter->iov_offset, iter->count);
 	size = bio_add_page(bio, bv->bv_page, len,
 				bv->bv_offset + iter->iov_offset);
-	if (size == len) {
+	if (unlikely(size != len))
+		return -EINVAL;
+
 	if (!bio_flagged(bio, BIO_NO_PAGE_REF)) {
 		struct page *page;
 		int i;
@@ -884,9 +886,6 @@ static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
 
 	iov_iter_advance(iter, size);
 	return 0;
-	}
-
-	return -EINVAL;
 }
 
 #define PAGE_PTRS_PER_BVEC     (sizeof(struct bio_vec) / sizeof(struct page *))