static size_t copy_page_to_iter_bvec(struct page *page, size_t offset, size_t bytes, struct iov_iter *i) { size_t skip, copy, wanted; const struct bio_vec *bvec; void *kaddr, *from; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; wanted = bytes; bvec = i->bvec; skip = i->iov_offset; copy = min_t(size_t, bytes, bvec->bv_len - skip); kaddr = kmap_atomic(page); from = kaddr + offset; memcpy_to_page(bvec->bv_page, skip + bvec->bv_offset, from, copy); skip += copy; from += copy; bytes -= copy; while (bytes) { bvec++; copy = min(bytes, (size_t)bvec->bv_len); memcpy_to_page(bvec->bv_page, bvec->bv_offset, from, copy); skip = copy; from += copy; bytes -= copy; } kunmap_atomic(kaddr); if (skip == bvec->bv_len) { bvec++; skip = 0; } i->count -= wanted - bytes; i->nr_segs -= bvec - i->bvec; i->bvec = bvec; i->iov_offset = skip; return wanted - bytes; }
size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i) { char *from = addr; if (unlikely(bytes > i->count)) bytes = i->count; if (unlikely(!bytes)) return 0; 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, (from += v.bv_len) - v.bv_len, v.bv_len), memcpy(v.iov_base, (from += v.iov_len) - v.iov_len, v.iov_len) ) return bytes; }