Re: [PATCH v2 00/10] evacuate struct page from the block layer, introduce __pfn_t
On Thu, May 7, 2015 at 8:58 AM, Linus Torvalds
<torvalds(a)linux-foundation.org> wrote:
On Thu, May 7, 2015 at 8:40 AM, Dan Williams
<dan.j.williams(a)intel.com> wrote:
>
> blkdev_get(FMODE_EXCL) is the protection in this case.
Ugh. That looks like a horrible nasty big hammer that will bite us
badly some day. Since you'd have to hold it for the whole IO. But I
guess it at least works.
Oh no, that wouldn't be per-I/O that would be permanent at
configuration set up time just like a raid member device.
Something like:
mdadm --create /dev/md0 --cache=/dev/pmem0p1 --storage=/dev/sda
Anyway, I did want to say that while I may not be convinced about
the
approach, I think the patches themselves don't look horrible. I
actually like your "__pfn_t". So while I (very obviously) have some
doubts about this approach, it may be that the most convincing
argument is just in the code.
Ok, I'll keep thinking about this and come back when we have a better
story about passing mmap'd persistent memory around in userspace.