diff --git a/fs/block_dev.c b/fs/block_dev.c
index 800f666c75a9..182ed1f788ff 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1919,6 +1919,7 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	struct inode *bd_inode = bdev_file_inode(file);
 	loff_t size = i_size_read(bd_inode);
 	struct blk_plug plug;
+	size_t shorted = 0;
 	ssize_t ret;
 
 	if (bdev_read_only(I_BDEV(bd_inode)))
@@ -1936,12 +1937,17 @@ ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
 	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
 		return -EOPNOTSUPP;
 
-	iov_iter_truncate(from, size - iocb->ki_pos);
+	size -= iocb->ki_pos;
+	if (iov_iter_count(from) > size) {
+		shorted = iov_iter_count(from) - size;
+		iov_iter_truncate(from, size);
+	}
 
 	blk_start_plug(&plug);
 	ret = __generic_file_write_iter(iocb, from);
 	if (ret > 0)
 		ret = generic_write_sync(iocb, ret);
+	iov_iter_reexpand(from, iov_iter_count(from) + shorted);
 	blk_finish_plug(&plug);
 	return ret;
 }
@@ -1953,13 +1959,21 @@ ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 	struct inode *bd_inode = bdev_file_inode(file);
 	loff_t size = i_size_read(bd_inode);
 	loff_t pos = iocb->ki_pos;
+	size_t shorted = 0;
+	ssize_t ret;
 
 	if (pos >= size)
 		return 0;
 
 	size -= pos;
-	iov_iter_truncate(to, size);
-	return generic_file_read_iter(iocb, to);
+	if (iov_iter_count(to) > size) {
+		shorted = iov_iter_count(to) - size;
+		iov_iter_truncate(to, size);
+	}
+
+	ret = generic_file_read_iter(iocb, to);
+	iov_iter_reexpand(to, iov_iter_count(to) + shorted);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(blkdev_read_iter);