Network drivers are using sendpage_ok() to check the first page of an
iterator in order to disable MSG_SPLICE_PAGES. The iterator can
represent list of contiguous pages.
When MSG_SPLICE_PAGES is enabled skb_splice_from_iter() is being used,
it requires all pages in the iterator to be sendable. Therefore it needs
to check that each page is sendable.
The patch introduces a helper sendpages_ok(), it returns true if all the
contiguous pages are sendable.
Drivers who want to send contiguous pages with MSG_SPLICE_PAGES may use
this helper to check whether the page list is OK. If the helper does not
return true, the driver should remove MSG_SPLICE_PAGES flag.
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
Signed-off-by: Ofir Gal <ofir.gal@xxxxxxxxxxx>
---
include/linux/net.h | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/include/linux/net.h b/include/linux/net.h
index 688320b79fcc..b75bc534c1b3 100644
--- a/include/linux/net.h
+++ b/include/linux/net.h
@@ -322,6 +322,25 @@ static inline bool sendpage_ok(struct page *page)
return !PageSlab(page) && page_count(page) >= 1;
}
+/*
+ * Check sendpage_ok on contiguous pages.
+ */
+static inline bool sendpages_ok(struct page *page, size_t len, size_t offset)
+{
+ struct page *p = page + (offset >> PAGE_SHIFT);
+ size_t count = 0;
+
+ while (count < len) {
+ if (!sendpage_ok(p))
+ return false;
+
+ p++;
+ count += PAGE_SIZE;
+ }
+
+ return true;
+}
+
int kernel_sendmsg(struct socket *sock, struct msghdr *msg, struct kvec *vec,
size_t num, size_t len);
int kernel_sendmsg_locked(struct sock *sk, struct msghdr *msg,
--
2.45.1
