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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>
This commit is contained in:
Al Viro 2014-02-05 12:44:24 -05:00
parent 240f3905f5
commit 70eca12d80
1 changed files with 39 additions and 58 deletions
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97
mm/process_vm_access.c
View File

@ -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 @@ static int process_vm_rw_single_vec(unsigned long addr,
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 @@ static int process_vm_rw_single_vec(unsigned long addr,
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;