fix copy_page_from_iter() for compound destinations
had been broken for ITER_BVEC et.al. since ever (OK, v3.17 when
ITER_BVEC had first appeared)...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4e3696d..4b7fce7 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -738,13 +738,27 @@ EXPORT_SYMBOL(copy_page_to_iter);
size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
- if (page_copy_sane(page, offset, bytes)) {
+ size_t res = 0;
+ if (!page_copy_sane(page, offset, bytes))
+ return 0;
+ page += offset / PAGE_SIZE; // first subpage
+ offset %= PAGE_SIZE;
+ while (1) {
void *kaddr = kmap_local_page(page);
- size_t wanted = _copy_from_iter(kaddr + offset, bytes, i);
+ size_t n = min(bytes, (size_t)PAGE_SIZE - offset);
+ n = _copy_from_iter(kaddr + offset, n, i);
kunmap_local(kaddr);
- return wanted;
+ res += n;
+ bytes -= n;
+ if (!bytes || !n)
+ break;
+ offset += n;
+ if (offset == PAGE_SIZE) {
+ page++;
+ offset = 0;
+ }
}
- return 0;
+ return res;
}
EXPORT_SYMBOL(copy_page_from_iter);
