On Wed, May 18, 2022 at 08:27:31PM -0700, Eric Biggers wrote: > > So the bio ends up with a total length that is a multiple of the logical block > size, but the lengths of the individual bvecs in the bio are *not* necessarily > multiples of the logical block size. That's the problem. I'm surely missing something here. I know the bvecs are not necessarily lbs aligned, but why does that matter? Is there some driver that can only take exactly 1 bvec, but allows it to be unaligned? If so, we could take the segment queue limit into account, but I am not sure that we need to. > Note, there's also lots of code that assumes that bio_vec::bv_len is a multiple > of 512. Could you point me to some examples? > That was implied by it being a multiple of the logical block size. But > the DMA alignment can be much lower, like 8 bytes (see nvme_set_queue_limits()). That's the driver this was tested on, though I just changed it to 4 bytes for 5.19.
