On 3/25/21 6:39 PM, Satya Tangirala wrote:

On Thu, Mar 25, 2021 at 02:51:31PM -0700, Bart Van Assche wrote:

quoted

Are you sure that the block layer core splits bios at logical block
boundaries? Commit 9cc5169cd478 ("block: Improve physical block
alignment of split bios") should have changed the behavior from
splitting at logical block boundaries into splitting at physical block
boundaries.

Ah, what I really meant with that sentence was "Currently, if a bio is
split, the size of the resulting bio is guaranteed to be aligned to a
the lbs. The endpoint of the bio might also be aligned to a physical
block boundary (which 9cc5169cd478 tries to achieve if possible), but
the bio's size (and hence also its endpoint since the start of the bio
is always lbs aligned) is *at least* lbs aligned". Does that sound
accurate?

That sounds better to me :-)

quoted

Without having looked at this patch series, can the same
effect be achieved by reporting the crypto data unit size as the
physical block size?

That would've been awesome, but I don't think we can do that :(
1) There isn't only one crypto data unit size. A device can support,
   and upper layers are free to use, many different data unit sizes.
2) IIUC 9cc5169cd478 (or more accurately get_max_io_size() since the
   function has been changed slightly since your original patch)
   doesn't align the size of the bio to the pbs - it only aligns the
   endpoint of the bio to the pbs (and it may actually not even do
   that if it turns out to not be possible). Is that right? If so,
   that means that if the startpoint of the bio isn't pbs aligned, the
   size of the bio won't be pbs aligned either.

Hmm ... if the start of a bio is not aligned to the physical block size
I don't think that the block layer can do anything about the start of
the bio. Anyway, I have taken a quick look at this patch series and the
patch series looks pretty clean to me. I will let Christoph review this
patch series since he already reviewed the previous version of this series.

Bart.