+ if (!write_to_vm) {
+ char __user *p = (char __user *) uaddr;
+
+ /*
+ * for a write, copy in data to kernel pages
+ */
+ ret = -EFAULT;
+ bio_for_each_segment(bvec, bio, i) {
+ char *addr = page_address(bvec->bv_page);
+
+ if (copy_from_user(addr, p, bvec->bv_len))
+ goto cleanup;
+ p += bvec->bv_len;
+ }
+ }
+
+ bio_set_map_data(bmd, bio);
+ return bio;
+cleanup:
+ bio_for_each_segment(bvec, bio, i)
+ __free_page(bvec->bv_page);
+
+ bio_put(bio);
+out_bmd:
+ bio_free_map_data(bmd);
+ return ERR_PTR(ret);
+}
+
+static struct bio *__bio_map_user_iov(request_queue_t *q,
+ struct block_device *bdev,
+ struct sg_iovec *iov, int iov_count,
+ int write_to_vm)
+{
+ int i, j;
+ int nr_pages = 0;
+ struct page **pages;
+ struct bio *bio;
+ int cur_page = 0;
+ int ret, offset;
+
+ for (i = 0; i < iov_count; i++) {
+ unsigned long uaddr = (unsigned long)iov[i].iov_base;
+ unsigned long len = iov[i].iov_len;
+ unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned long start = uaddr >> PAGE_SHIFT;
+
+ nr_pages += end - start;
+ /*
+ * transfer and buffer must be aligned to at least hardsector
+ * size for now, in the future we can relax this restriction
+ */
+ if ((uaddr & queue_dma_alignment(q)) || (len & queue_dma_alignment(q)))
+ return ERR_PTR(-EINVAL);
+ }
+
+ if (!nr_pages)
+ return ERR_PTR(-EINVAL);
+
+ bio = bio_alloc(GFP_KERNEL, nr_pages);
+ if (!bio)
+ return ERR_PTR(-ENOMEM);
+
+ ret = -ENOMEM;
+ pages = kcalloc(nr_pages, sizeof(struct page *), GFP_KERNEL);
+ if (!pages)
+ goto out;
+
+ for (i = 0; i < iov_count; i++) {
+ unsigned long uaddr = (unsigned long)iov[i].iov_base;
+ unsigned long len = iov[i].iov_len;
+ unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ unsigned long start = uaddr >> PAGE_SHIFT;
+ const int local_nr_pages = end - start;
+ const int page_limit = cur_page + local_nr_pages;
+
+ down_read(¤t->mm->mmap_sem);
+ ret = get_user_pages(current, current->mm, uaddr,
+ local_nr_pages,
+ write_to_vm, 0, &pages[cur_page], NULL);
+ up_read(¤t->mm->mmap_sem);
+
+ if (ret < local_nr_pages) {
+ ret = -EFAULT;
+ goto out_unmap;
+ }
+
+ offset = uaddr & ~PAGE_MASK;
+ for (j = cur_page; j < page_limit; j++) {
+ unsigned int bytes = PAGE_SIZE - offset;
+
+ if (len <= 0)
+ break;
+
+ if (bytes > len)
+ bytes = len;
+
+ /*
+ * sorry...
+ */
+ if (bio_add_pc_page(q, bio, pages[j], bytes, offset) <
+ bytes)
+ break;
+
+ len -= bytes;
+ offset = 0;
+ }
+
+ cur_page = j;
+ /*
+ * release the pages we didn't map into the bio, if any
+ */
+ while (j < page_limit)
+ page_cache_release(pages[j++]);
+ }