Re: [PATCH 3/5] nvme: add support for copy offload

Caleb Sander Mateos
2025-05-23T14:22:39Z

On Fri, May 23, 2025 at 5:50 AM Christoph Hellwig <hch@infradead.org> wrote:
>
> On Thu, May 22, 2025 at 03:54:46PM +0200, Hannes Reinecke wrote:
> > > + if (req->cmd_flags & REQ_FUA)
> > > + control |= NVME_RW_FUA;
> > > + if (req->cmd_flags & REQ_FAILFAST_DEV)
> > > + control |= NVME_RW_LR;
> >
> > FAILFAST_DEV? Is that even set anywhere?
>
> That is a good question, but this is consistent with what we do for
> other I/O commands.

Looks like it might be set by blk_mq_bio_to_request() and
blk_update_mixed_merge() for read-ahead bios:
#define REQ_FAILFAST_MASK \
(REQ_FAILFAST_DEV | REQ_FAILFAST_TRANSPORT | REQ_FAILFAST_DRIVER)

if (bio->bi_opf & REQ_RAHEAD)
rq->cmd_flags |= REQ_FAILFAST_MASK;

Best,
Caleb