On Tue, Mar 17, 2015 at 6:02 AM, Matthew Wilcox <willy@xxxxxxxxxxxxxxx> wrote:
> On Mon, Mar 16, 2015 at 11:05:33PM +0000, Al Viro wrote:
>> > diff --git a/mm/iov_iter.c b/mm/iov_iter.c
>> > index 827732047da1..be9a7c5b8703 100644
>> > --- a/mm/iov_iter.c
>> > +++ b/mm/iov_iter.c
>> > @@ -61,7 +61,7 @@
>> > __p = i->bvec; \
>> > __v.bv_len = min_t(size_t, n, __p->bv_len - skip); \
>> > if (likely(__v.bv_len)) { \
>> > - __v.bv_page = __p->bv_page; \
>> > + __v.bv_pfn = __p->bv_pfn; \
>> > __v.bv_offset = __p->bv_offset + skip; \
>> > (void)(STEP); \
>> > skip += __v.bv_len; \
>> > @@ -72,7 +72,7 @@
>> > __v.bv_len = min_t(size_t, n, __p->bv_len); \
>> > if (unlikely(!__v.bv_len)) \
>> > continue; \
>> > - __v.bv_page = __p->bv_page; \
>> > + __v.bv_pfn = __p->bv_pfn; \
>> > __v.bv_offset = __p->bv_offset; \
>> > (void)(STEP); \
>> > skip = __v.bv_len; \
>> > @@ -369,7 +369,7 @@ size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i)
>> > iterate_and_advance(i, bytes, v,
>> > __copy_to_user(v.iov_base, (from += v.iov_len) - v.iov_len,
>> > v.iov_len),
>> > - memcpy_to_page(v.bv_page, v.bv_offset,
>> > + memcpy_to_page(bvec_page(&v), v.bv_offset,
>>
>> How had memcpy_to_page(NULL, ...) worked for you?
>
> static inline struct page *bvec_page(const struct bio_vec *bvec)
> {
> - return bvec->bv_page;
> + return pfn_to_page(bvec->bv_pfn.pfn);
> }
>
> (yes, more work to be done here to make copy_to_iter work to a bvec that
> is actually targetting a page-less address, but these are RFC patches
> showing the direction we're heading in while keeping current code working)
>
Right, the next item to tackle is kmap() and kmap_atomic() before we
can start converting paths to be "native" pfn-only.
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