On Sat, Nov 04, 2017 at 09:18:25AM +0100, Christoph Hellwig wrote: > On Fri, Nov 03, 2017 at 09:02:04AM -0600, Keith Busch wrote: > > If the namespace has metadata, but the request doesn't have a metadata > > payload attached to it for whatever reason, we can't construct the command > > for that format. We also can't have the controller strip/generate the > > payload with PRACT bit set if it's not a T10 format, so we just fail > > the command. > > The only metadata payload a READ or WRITE request can have is a protection > information one. For a namespace formatted with protection information > bio_integrity_prep as called from blk_mq_make_request will ensure we > always have metadata attached. > > If a namespace is formatted with non-PI metadata we will never have > metadata attached to the bio/request and should not even present the > namespace to the kernel. That's not quite right. For non-PI metadata formats, we use the 'nop_profile', which gets the metadata buffer allocated so we can safely use a metadata formatted namespace. There's no in-kernel user of the allocated payload, but we still need the metadata buffer in order to use the namespace at all.
