On Mon, Aug 04, 2025 at 08:54:00AM +0200, Hannes Reinecke wrote:

On 8/2/25 01:47, Keith Busch wrote:

quoted

+static int bio_align_to_lbs(struct bio *bio, struct iov_iter *iter)
+{
+	struct block_device *bdev = bio->bi_bdev;
+	size_t nbytes;
+
+	if (!bdev)
+		return 0;
+
+	nbytes = bio->bi_iter.bi_size & (bdev_logical_block_size(bdev) - 1);
+	if (!nbytes)
+		return 0;
+
+	bio_revert(bio, nbytes);
+	iov_iter_revert(iter, nbytes);
+	if (!bio->bi_iter.bi_size)
+		return -EFAULT;
+
+	return 0;
+}
+
  /**
   * bio_iov_iter_get_pages - add user or kernel pages to a bio
   * @bio: bio to add pages to

@@ -1336,6 +1355,7 @@ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
  		ret = __bio_iov_iter_get_pages(bio, iter);
  	} while (!ret && iov_iter_count(iter) && !bio_full(bio, 0));
+	ret = bio_align_to_lbs(bio, iter);
  	return bio->bi_vcnt ? 0 : ret;

Wouldn't that cause the error from bio_align_to_lba() to be ignored
if bio->bi_vcnt is greater than 0?

That returns an error only if the alignment reduces the size to 0, so
there would be a bug somewhere if bi_vcnt is not also 0 in that case.