process_vm_access: take get_user_pages/put_pages one level up
... and trim the fuck out of process_vm_rw_pages() argument list.
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 70ec315..c2a1916 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -39,69 +39,39 @@
* @bytes_copied: returns number of bytes successfully copied
* Returns 0 on success, error code otherwise
*/
-static int process_vm_rw_pages(struct task_struct *task,
- struct mm_struct *mm,
- struct page **process_pages,
- unsigned long pa,
- unsigned long start_offset,
+static int process_vm_rw_pages(struct page **pages,
+ unsigned offset,
unsigned long len,
struct iov_iter *iter,
int vm_write,
unsigned int nr_pages_to_copy,
ssize_t *bytes_copied)
{
- int pages_pinned;
- int pgs_copied = 0;
- int j;
- int ret;
- ssize_t bytes_to_copy;
- ssize_t rc = 0;
-
*bytes_copied = 0;
- /* Get the pages we're interested in */
- down_read(&mm->mmap_sem);
- pages_pinned = get_user_pages(task, mm, pa,
- nr_pages_to_copy,
- vm_write, 0, process_pages, NULL);
- up_read(&mm->mmap_sem);
-
- if (pages_pinned != nr_pages_to_copy) {
- rc = -EFAULT;
- goto end;
- }
-
/* Do the copy for each page */
- for (pgs_copied = 0;
- (pgs_copied < nr_pages_to_copy) && iov_iter_count(iter);
- pgs_copied++) {
- struct page *page = process_pages[pgs_copied];
- bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset, len);
+ while (iov_iter_count(iter) && nr_pages_to_copy--) {
+ struct page *page = *pages++;
+ size_t copy = min_t(ssize_t, PAGE_SIZE - offset, len);
+ size_t copied;
if (vm_write) {
- if (bytes_to_copy > iov_iter_count(iter))
- bytes_to_copy = iov_iter_count(iter);
- ret = iov_iter_copy_from_user(page,
- iter, start_offset, bytes_to_copy);
- iov_iter_advance(iter, ret);
+ if (copy > iov_iter_count(iter))
+ copy = iov_iter_count(iter);
+ copied = iov_iter_copy_from_user(page, iter,
+ offset, copy);
+ iov_iter_advance(iter, copied);
set_page_dirty_lock(page);
} else {
- ret = copy_page_to_iter(page, start_offset,
- bytes_to_copy, iter);
+ copied = copy_page_to_iter(page, offset, copy, iter);
}
- *bytes_copied += ret;
- len -= ret;
- if (ret < bytes_to_copy && iov_iter_count(iter)) {
- rc = -EFAULT;
- break;
- }
- start_offset = 0;
+ *bytes_copied += copied;
+ len -= copied;
+ if (copied < copy && iov_iter_count(iter))
+ return -EFAULT;
+ offset = 0;
}
-
-end:
- for (j = 0; j < pages_pinned; j++)
- put_page(process_pages[j]);
- return rc;
+ return 0;
}
/* Maximum number of pages kmalloc'd to hold struct page's during copy */
@@ -138,7 +108,6 @@
ssize_t bytes_copied_loop;
ssize_t rc = 0;
unsigned long nr_pages_copied = 0;
- unsigned long nr_pages_to_copy;
unsigned long max_pages_per_loop = PVM_MAX_KMALLOC_PAGES
/ sizeof(struct pages *);
@@ -150,23 +119,35 @@
nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
while ((nr_pages_copied < nr_pages) && iov_iter_count(iter)) {
+ int nr_pages_to_copy;
+ int pages_pinned;
nr_pages_to_copy = min(nr_pages - nr_pages_copied,
max_pages_per_loop);
- rc = process_vm_rw_pages(task, mm, process_pages, pa,
+ /* Get the pages we're interested in */
+ down_read(&mm->mmap_sem);
+ pages_pinned = get_user_pages(task, mm, pa,
+ nr_pages_to_copy,
+ vm_write, 0, process_pages, NULL);
+ up_read(&mm->mmap_sem);
+
+ if (pages_pinned <= 0)
+ return -EFAULT;
+
+ rc = process_vm_rw_pages(process_pages,
start_offset, len, iter,
- vm_write, nr_pages_to_copy,
+ vm_write, pages_pinned,
&bytes_copied_loop);
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) {
- return rc;
- } else {
- len -= bytes_copied_loop;
- nr_pages_copied += nr_pages_to_copy;
- pa += nr_pages_to_copy * PAGE_SIZE;
- }
+ if (rc < 0)
+ break;
}
return rc;