On Mon, Jan 23, 2017 at 8:00 AM, Christoph Hellwig <hch(a)lst.de> wrote:
On Sun, Jan 22, 2017 at 11:10:04PM -0800, Dan Williams wrote:
> How about we solve the copy_from_user() abuse first before we hijack
> this thread for some future feature that afaics has no patches posted
Solving copy_from_user abuse first sounds perfectly fine to me. But
please do so without abusing the block layer for persistent memory
access. Given that we don't have use cases for different pmem access
methods in a single OS image yet let's avoid introducing new ops
for now and just remove the copy_from_user abuse.
The use case that we have now is distinguishing volatile vs persistent
memory (brd vs pmem).
I took a look at mtd layering approach and the main difference is that
layers above the block layer do not appear to know anything about mtd
specifics. For fs/dax.c we currently need some path to retrieve a dax
anchor object through the block device.
In the longer run I like your dax_operations, but they need to be
separate from the block layer.
I'll move them from block_device_operations to dax data hanging off of
the bdev_inode, or is there a better way to go from bdev-to-dax?