Re: [PATCH 0/5] target/rbd: distributed lun reset support

[Christoph Hellwig <hch@infradead.org>]

On Tue, May 05, 2015 at 11:49:10PM -0500, Mike Christie wrote:
> On 05/05/2015 12:49 PM, Christoph Hellwig wrote:
> > Can you explain why you want to hook into the lun reset code?  I know
> > the PR code needs to issue implicit task aborts, but I don't
> > understand the need to do something with lun resets.
> 
> I thought if you exported a LU through multiple LIO nodes and its ALUA
> state was active optimized/non-optimized on those nodes, then you would
> have to do similar cleanup across the cluster. For example, don't we
> have to fail commands on those other nodes, and then also depending on
> the TAS bit value return task aborted statuses?

Oh, you're actually implementing active/active exports.  Yes, in that
case we'll need to distribute LUN resets.

> > As for the API:  I would much prefer to have things at the block layer
> > in some form than adding side band protocol for specific functionality.
> > 
> 
> Ok. For what you need for your NFS cluster work, will you have a
> request_queue or block_device or gendisk?

All of them.  It's just another consumer of the in-kernel block devices
interface.