Assuming we are reading data from the device, if the bio_vec contains a contiguous segment in memory where to data can be written by the driver, is the bvec->len field a multiple of our device's sector (or better yet, a multiple of a block)?
In case it's not, should the driver create memory regions where the data should be written by the device, and only then write len bytes to the page + offset address of the bio_vec struct?