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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>
This commit is contained in:
Al Viro 2014-02-05 12:55:11 -05:00
parent 70eca12d80
commit e21345f9c3
1 changed files with 14 additions and 8 deletions
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22
mm/process_vm_access.c
View File

@ -41,20 +41,22 @@
*/ */
static int process_vm_rw_pages(struct page **pages, static int process_vm_rw_pages(struct page **pages,
unsigned offset, unsigned offset,
unsigned long len, size_t len,
struct iov_iter *iter, struct iov_iter *iter,
int vm_write, int vm_write,
unsigned int nr_pages_to_copy,
ssize_t *bytes_copied) ssize_t *bytes_copied)
{ {
*bytes_copied = 0; *bytes_copied = 0;
/* Do the copy for each page */ /* 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++; struct page *page = *pages++;
size_t copy = min_t(ssize_t, PAGE_SIZE - offset, len); size_t copy = PAGE_SIZE - offset;
size_t copied; size_t copied;
if (copy > len)
copy = len;
if (vm_write) { if (vm_write) {
if (copy > iov_iter_count(iter)) if (copy > iov_iter_count(iter))
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)) { while ((nr_pages_copied < nr_pages) && iov_iter_count(iter)) {
int nr_pages_to_copy; int nr_pages_to_copy;
int pages_pinned; int pages_pinned;
size_t n;
nr_pages_to_copy = min(nr_pages - nr_pages_copied, nr_pages_to_copy = min(nr_pages - nr_pages_copied,
max_pages_per_loop); max_pages_per_loop);
@ -134,18 +137,21 @@ static int process_vm_rw_single_vec(unsigned long addr,
if (pages_pinned <= 0) if (pages_pinned <= 0)
return -EFAULT; return -EFAULT;
n = pages_pinned * PAGE_SIZE - start_offset;
if (n > len)
n = len;
rc = process_vm_rw_pages(process_pages, rc = process_vm_rw_pages(process_pages,
start_offset, len, iter, start_offset, n, iter,
vm_write, pages_pinned, vm_write,
&bytes_copied_loop); &bytes_copied_loop);
len -= n;
start_offset = 0; start_offset = 0;
*bytes_copied += bytes_copied_loop; *bytes_copied += bytes_copied_loop;
len -= bytes_copied_loop;
nr_pages_copied += pages_pinned; nr_pages_copied += pages_pinned;
pa += pages_pinned * PAGE_SIZE; pa += pages_pinned * PAGE_SIZE;
while (pages_pinned) while (pages_pinned)
put_page(process_pages[--pages_pinned]); put_page(process_pages[--pages_pinned]);
if (rc < 0) if (rc < 0)
break; break;
} }