Re: [PATCH v9 02/10] dax: Introduce holder for dax_device

[Shiyang Ruan]

在 2022/1/20 16:46, Christoph Hellwig 写道:
> On Wed, Jan 05, 2022 at 04:12:04PM -0800, Dan Williams wrote:
> > We ended up with explicit callbacks after hch balked at a notifier
> > call-chain, but I think we're back to that now. The partition mistake
> > might be unfixable, but at least bdev_dax_pgoff() is dead. Notifier
> > call chains have their own locking so, Ruan, this still does not need
> > to touch dax_read_lock().
>
> I think we have a few options here:
>
>   (1) don't allow error notifications on partitions.  And error return from
>       the holder registration with proper error handling in the file
>       system would give us that
>   (2) extent the holder mechanism to cover a range
>   (3) bite the bullet and create a new stacked dax_device for each
>       partition
>
> I think (1) is the best option for now.  If people really do need
> partitions we'll have to go for (3)

Yes, I agree.  I'm doing it the first way right now.

I think that since we can use namespace to divide a big NVDIMM into 
multiple pmems, partition on a pmem seems not so meaningful.


--
Thanks,
Ruan.