@@ -957,11 +957,9 @@ static inline bool page_copy_sane(struct page *page, size_t offset, size_t n)
return false;
}
-size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+static size_t __copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (unlikely(!page_copy_sane(page, offset, bytes)))
- return 0;
if (i->type & (ITER_BVEC | ITER_KVEC | ITER_XARRAY)) {
void *kaddr = kmap_atomic(page);
size_t wanted = copy_to_iter(kaddr + offset, bytes, i);
@@ -974,6 +972,30 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
else
return copy_page_to_iter_pipe(page, offset, bytes, i);
}
+
+size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
+ struct iov_iter *i)
+{
+ size_t res = 0;
+ if (unlikely(!page_copy_sane(page, offset, bytes)))
+ return 0;
+ page += offset / PAGE_SIZE; // first subpage
+ offset %= PAGE_SIZE;
+ while (1) {
+ size_t n = __copy_page_to_iter(page, offset,
+ min(bytes, (size_t)PAGE_SIZE - offset), i);
+ res += n;
+ bytes -= n;
+ if (!bytes || !n)
+ break;
+ offset += n;
+ if (offset == PAGE_SIZE) {
+ page++;
+ offset = 0;
+ }
+ }
+ return res;
+}
EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
In situation when copy_page_to_iter() got a compound page the current code would only work on systems with no CONFIG_HIGHMEM. It *is* the majority of real-world setups, or we would've drown in bug reports by now. Still needs fixing. Current variant works for solitary page; rename that to __copy_page_to_iter() and turn the handling of compound pages into a loop over subpages. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> --- lib/iov_iter.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-)