On Wed, Mar 25, 2020 at 01:23:33PM -0400, Martin K. Petersen wrote:

Christoph,

quoted

I am very much against that for the following reason:

 - the current REQ_OP_DISCARD is purely a hint, and implementations can
   (and do) choose to ignore it

 - REQ_OP_WRITE_ZEROES is an actual data integrity operation with
   everything that entails

If you want to keep emphasis on the "integrity operation" instead of the
provisioning aspect, would you expect REQ_ALLOCATE (which may or may not
zero blocks) to be considered a deterministic operation or a
non-deterministic one? Should this depend on whether the device
guarantees zeroing when provisioning blocks or not?

That's why I don't like the whole flags game very much.  I'd rather
have REQ_OP_WRITE_ZEROES as the integrity operation that gurantees
zeroing, and a REQ_ALLOCATE that doesn't guarantee zeroing, just some
deterministic state of the blocks.