block: don't run get_page() on pages from non-bvec iov iter

The refcount has been increased for pages retrieved from non-bvec iov iter
via __bio_iov_iter_get_pages(), so don't need to do that again.

Otherwise, IO pages are leaked easily.

Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Fixes: 7321ecbfc7 ("block: change how we get page references in bio_iov_iter_get_pages")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -992,7 +992,7 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 
 	if (iov_iter_bvec_no_ref(iter))
 		bio_set_flag(bio, BIO_NO_PAGE_REF);
-	else
+	else if (is_bvec)
 		bio_get_pages(bio);
 
 	return bio->bi_vcnt ? 0 : ret;