process_vm_rw_pages(): pass accurate amount of bytes

... makes passing the amount of pages unnecessary

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index c2a1916..83252d7 100644 (file)
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -41,20 +41,22 @@
  */
 static int process_vm_rw_pages(struct page **pages,
                               unsigned offset,
-                              unsigned long len,
+                              size_t len,
                               struct iov_iter *iter,
                               int vm_write,
-                              unsigned int nr_pages_to_copy,
                               ssize_t *bytes_copied)
 {
        *bytes_copied = 0;
 
        /* Do the copy for each page */
-       while (iov_iter_count(iter) && nr_pages_to_copy--) {
+       while (iov_iter_count(iter) && len) {
                struct page *page = *pages++;
-               size_t copy = min_t(ssize_t, PAGE_SIZE - offset, len);
+               size_t copy = PAGE_SIZE - offset;
                size_t copied;
 
+               if (copy > len)
+                       copy = len;
+
                if (vm_write) {
                        if (copy > iov_iter_count(iter))
                                copy = iov_iter_count(iter);
@@ -121,6 +123,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
        while ((nr_pages_copied < nr_pages) && iov_iter_count(iter)) {
                int nr_pages_to_copy;
                int pages_pinned;
+               size_t n;
                nr_pages_to_copy = min(nr_pages - nr_pages_copied,
                                       max_pages_per_loop);
 
@@ -134,18 +137,21 @@ static int process_vm_rw_single_vec(unsigned long addr,
                if (pages_pinned <= 0)
                        return -EFAULT;
 
+               n = pages_pinned * PAGE_SIZE - start_offset;
+               if (n > len)
+                       n = len;
+
                rc = process_vm_rw_pages(process_pages,
-                                        start_offset, len, iter,
-                                        vm_write, pages_pinned,
+                                        start_offset, n, iter,
+                                        vm_write,
                                         &bytes_copied_loop);
+               len -= n;
                start_offset = 0;
                *bytes_copied += bytes_copied_loop;
-               len -= bytes_copied_loop;
                nr_pages_copied += pages_pinned;
                pa += pages_pinned * PAGE_SIZE;
                while (pages_pinned)
                        put_page(process_pages[--pages_pinned]);
-
                if (rc < 0)
                        break;
        }