[dm-devel] [PATCH v5] blk-mq: introduce BLK_STS_DEV_RESOURCE

[Bart Van Assche]

On Tue, 2018-01-30 at 20:22 -0700, Jens Axboe wrote:
> On 1/30/18 8:21 PM, Bart Van Assche wrote:
> > On Tue, 2018-01-30 at 20:17 -0700, Jens Axboe wrote:
> > > BLK_STS_RESOURCE should always be safe to return, and it should work
> > > the same as STS_DEV_RESOURCE, except it may cause an extra queue
> > > run.
> > > 
> > > Well written drivers should use STS_DEV_RESOURCE where it makes
> > > sense.
> > 
> > Hello Jens,
> > 
> > I would appreciate it if other names would be chosen than BLK_STS_RESOURCE
> > and BLK_STS_DEV_RESOURCE, e.g. names that directly refer to the fact that
> > one of the two status codes causes the queue to be rerun and the other not.
> > I'm afraid that the currently chosen names will cause confusion.
> 
> DEV_RESOURCE is pretty clear I think, but I agree that STS_RESOURCE
> could perhaps be better. STS_SYSTEM_RESOURCE? It makes the distinction
> a bit clearer.

I'm concerned about both. A block driver can namely run out of device resources
without receiving a notification if that resource becomes available again. In
that case the appropriate return code is BLK_STS_RESOURCE. Hence my concern ...

Bart.