[PATCH] NVMe: Add rw_page support

[Keith Busch]

On Fri, 14 Nov 2014, Jens Axboe wrote:
> On 11/14/2014 03:50 PM, Keith Busch wrote:
>> But nvme_cmd_info does not contain the opcode. I do have the struct
>> request here, and I can certainly pull the data direction from its
>> cmd_flags, so thanks for the suggestion!
>>
>> Now I wonder if there's something else unused in a request that I
>> can repurpose to save the dma_addr_t in so I don't add it in the
>> nvme_cmd_info...
>
> For the rw_page path, you don't use ->special to store the iod. So you
> could use that... That might break for 32-bit platforms and 64-bit DMA,
> though. If you really want to get nasty, ->__cmd is 16 bytes of unused
> goodness as well, though I do want to make that one dynamically
> allocated for the queues that need it.

Ah, but I already got req->special pointing to the page. Maybe we can
union another field with a new "special_2" field.