Re: [PATCH v3 13/14] filesystem-dax: gate calls to dax_flush() on QUEUE_FLAG_WC

[Dan Williams]

On Sun, Jun 18, 2017 at 1:45 AM, Christoph Hellwig <hch@xxxxxx> wrote:
> On Fri, Jun 09, 2017 at 01:24:56PM -0700, Dan Williams wrote:
>> Some platforms arrange for cpu caches to be flushed on power-fail. On
>> those platforms there is no requirement that the kernel track and flush
>> potentially dirty cache lines. Given that we still insert entries into
>> the radix for locking purposes this patch only disables the cache flush
>> loop, not the dirty tracking.
>>
>> Userspace can override the default cache setting via the block device
>> queue "write_cache" attribute in sysfs.
>
> NAK.  Please stop using the block infrastructure for dax values.  Have
> your own flag and sysfs file in the dax infrastructure and only propagate
> it to the block layer for the block devices using dax.

Ok, that makes sense.