From: Dan Williams [mailto:[email protected]]
> A couple weeks back, in the course of reviewing the memcpy_nocache()
> proposal from Brian, Linus subtly suggested that the pmem specific
> memcpy_to_pmem() routine be moved to be implemented at the driver
> level [1]:
Of course, there may not be a backing device either! That will depend on the
filesystem.
I see two possible routes here:
1. Add a new address_space_operation:
const struct dax_operations *(*get_dax_ops)(struct address_space *);
2. Add two of the dax_operations to address_space_operations:
size_t (*copy_from_iter)(struct address_space *, void *, size_t, struct
iov_iter *);
void (*flush)(struct address_space *, void *, size_t);
(we won't need ->direct_access as an address_space op because that'll be
handled a different way in the brave new world that supports non-bdev-based
filesystems)
Obviously in either case we'd have generic bdev versions for ext4, xfs and
other block based filesystems, but filesystems with a character device or a
network protocol behind them would do whatever it is they need to do.
I kind of prefer the second option, but does anyone else have a preference?
