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authorAl Viro <viro@zeniv.linux.org.uk>2014-02-05 12:14:11 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2014-04-01 23:19:27 -0400
commit240f3905f513cd5f27cc3f79bf03bf3f88323f41 (patch)
tree69247be2e360e3cceb330773df9d50f34652dd73
parent9f78bdfabf0de0bc8d3cc97d06908651b577a567 (diff)
process_vm_access: switch to copy_page_to_iter/iov_iter_copy_from_user
... rather than open-coding those. As a side benefit, we get much saner loop calling those; we can just feed entire pages, instead of the "copy would span the iovec boundary, let's do it in two loop iterations" mess. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--mm/process_vm_access.c91
1 files changed, 23 insertions, 68 deletions
diff --git a/mm/process_vm_access.c b/mm/process_vm_access.c
index 1e3c81103b2c..70ec3156f45a 100644
--- a/mm/process_vm_access.c
+++ b/mm/process_vm_access.c
@@ -51,13 +51,11 @@ static int process_vm_rw_pages(struct task_struct *task,
ssize_t *bytes_copied)
{
int pages_pinned;
- void *target_kaddr;
int pgs_copied = 0;
int j;
int ret;
ssize_t bytes_to_copy;
ssize_t rc = 0;
- const struct iovec *iov = iter->iov;
*bytes_copied = 0;
@@ -75,77 +73,34 @@ static int process_vm_rw_pages(struct task_struct *task,
/* Do the copy for each page */
for (pgs_copied = 0;
- (pgs_copied < nr_pages_to_copy) && iter->nr_segs;
+ (pgs_copied < nr_pages_to_copy) && iov_iter_count(iter);
pgs_copied++) {
- /* Make sure we have a non zero length iovec */
- while (iter->nr_segs && iov->iov_len == 0) {
- iov++;
- iter->nr_segs--;
+ struct page *page = process_pages[pgs_copied];
+ bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset, len);
+
+ 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);
+ set_page_dirty_lock(page);
+ } else {
+ ret = copy_page_to_iter(page, start_offset,
+ bytes_to_copy, iter);
}
- if (!iter->nr_segs)
- break;
-
- /*
- * Will copy smallest of:
- * - bytes remaining in page
- * - bytes remaining in destination iovec
- */
- bytes_to_copy = min_t(ssize_t, PAGE_SIZE - start_offset,
- len - *bytes_copied);
- bytes_to_copy = min_t(ssize_t, bytes_to_copy,
- iov->iov_len
- - iter->iov_offset);
-
- target_kaddr = kmap(process_pages[pgs_copied]) + start_offset;
-
- if (vm_write)
- ret = copy_from_user(target_kaddr,
- iov->iov_base
- + iter->iov_offset,
- bytes_to_copy);
- else
- ret = copy_to_user(iov->iov_base
- + iter->iov_offset,
- target_kaddr, bytes_to_copy);
- kunmap(process_pages[pgs_copied]);
- if (ret) {
- *bytes_copied += bytes_to_copy - ret;
- pgs_copied++;
+ *bytes_copied += ret;
+ len -= ret;
+ if (ret < bytes_to_copy && iov_iter_count(iter)) {
rc = -EFAULT;
- goto end;
- }
- *bytes_copied += bytes_to_copy;
- iter->iov_offset += bytes_to_copy;
- if (iter->iov_offset == iov->iov_len) {
- /*
- * Need to copy remaining part of page into the
- * next iovec if there are any bytes left in page
- */
- iter->nr_segs--;
- iov++;
- iter->iov_offset = 0;
- start_offset = (start_offset + bytes_to_copy)
- % PAGE_SIZE;
- if (start_offset)
- pgs_copied--;
- } else {
- start_offset = 0;
+ break;
}
+ start_offset = 0;
}
end:
- if (vm_write) {
- for (j = 0; j < pages_pinned; j++) {
- if (j < pgs_copied)
- set_page_dirty_lock(process_pages[j]);
- put_page(process_pages[j]);
- }
- } else {
- for (j = 0; j < pages_pinned; j++)
- put_page(process_pages[j]);
- }
-
- iter->iov = iov;
+ for (j = 0; j < pages_pinned; j++)
+ put_page(process_pages[j]);
return rc;
}
@@ -194,7 +149,7 @@ static int process_vm_rw_single_vec(unsigned long addr,
return 0;
nr_pages = (addr + len - 1) / PAGE_SIZE - addr / PAGE_SIZE + 1;
- while ((nr_pages_copied < nr_pages) && iter->nr_segs) {
+ while ((nr_pages_copied < nr_pages) && iov_iter_count(iter)) {
nr_pages_to_copy = min(nr_pages - nr_pages_copied,
max_pages_per_loop);
@@ -303,7 +258,7 @@ static ssize_t process_vm_rw_core(pid_t pid, struct iov_iter *iter,
goto put_task_struct;
}
- for (i = 0; i < riovcnt && iter->nr_segs; i++) {
+ for (i = 0; i < riovcnt && iov_iter_count(iter); i++) {
rc = process_vm_rw_single_vec(
(unsigned long)rvec[i].iov_base, rvec[i].iov_len,
iter, process_pages, mm, task, vm_write,