On Thu, 2015-08-13 at 14:11 -0700, Dan Williams wrote:
> On Thu, Aug 13, 2015 at 9:51 AM, Ross Zwisler
> <ross.zwisler@xxxxxxxxxxxxxxx> wrote:
> > Update the DAX I/O path so that all operations that store data (I/O
> > writes, zeroing blocks, punching holes, etc.) properly synchronize the
> > stores to media using the PMEM API. This ensures that the data DAX is
> > writing is durable on media before the operation completes.
> >
> > Signed-off-by: Ross Zwisler <ross.zwisler@xxxxxxxxxxxxxxx>
> [..]
> > @@ -145,18 +147,27 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
> > retval = dax_get_addr(bh, &addr, blkbits);
> > if (retval < 0)
> > break;
> > - if (buffer_unwritten(bh) || buffer_new(bh))
> > + if (buffer_unwritten(bh) || buffer_new(bh)) {
> > dax_new_buf(addr, retval, first, pos,
> > end);
> > + need_wmb = true;
> > + }
> > addr += first;
> > size = retval - first;
> > }
> > max = min(pos + size, end);
> > }
> >
> > - if (iov_iter_rw(iter) == WRITE)
> > + if (iov_iter_rw(iter) == WRITE) {
> > len = copy_from_iter_nocache(addr, max - pos, iter);
> > - else if (!hole)
> > + /*
> > + * copy_from_iter_nocache() uses non-temporal stores
> > + * for iovec iterators so we can skip the write back.
> > + */
> > + if (!iter_is_iovec(iter))
> > + wb_cache_pmem((void __pmem *)addr, max - pos);
> > + need_wmb = true;
>
> I think this should become copy_from_iter_pmem() and hide the
> wb_cache_pmem() as an internal arch detail. I.e. wb_cache_pmem()
> should not be a global api when its usage is architecture specific.
> Otherwise are you asserting that all architecture implementations of
> copy_from_iter_nocache() are pmem safe?
Great point. Nope, copy_from_iter_nocache() uses __copy_from_user_nocache(),
which just defaults to __copy_from_user() on non-x86. Dang, the PMEM API just
keeps growing... :(
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