Re: [PATCH 4/6] dm,dax,pmem: prepare dax_copy_to/from_iter() APIs with DAXDEV_F_RECOVERY

[Jane Chu]

On 10/21/2021 10:33 PM, Christoph Hellwig wrote:
> On Fri, Oct 22, 2021 at 12:49:15AM +0000, Jane Chu wrote:
>> I've looked through your "futher decouple DAX from block devices" series
>> and likes the use of xarray in place of the host hash list.
>> Which upstream version is the series based upon?
>> If it's based on your development repo, I'd be happy to take a clone
>> and rebase my patches on yours if you provide a link. Please let me
>> know the best way to cooperate.
> 
> It is based on linux-next from when it was posted.  A git tree is here:
> 
> http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dax-block-cleanup
> 
>> That said, I'm unclear at what you're trying to suggest with respect
>> to the 'DAXDEV_F_RECOVERY' flag.  The flag came from upper dax-fs
>> call stack to the dm target layer, and the dm targets are equipped
>> with handling pmem driver specific task, so it appears that the flag
>> would need to be passed down to the native pmem layer, right?
>> Am I totally missing your point?
> 
> We'll need to pass it through (assuming we want to keep supporting
> dm, see the recent discussion with Dan).
> 
> FYI, here is a sketch where I'd like to move to, but this isn't properly
> tested yet:
> 
> http://git.infradead.org/users/hch/misc.git/shortlog/refs/heads/dax-devirtualize
> 
> To support something like DAXDEV_F_RECOVERYwe'd need a separate
> dax_operations methods.  Which to me suggest it probably should be
> a different operation (fallocate / ioctl / etc) as Darrick did earlier.
> 

Thanks for the info!
-jane