net: allow better page reuse in splice(sock -> pipe)

splice() from socket to pipe needs linear_to_page() helper to transfert
skb header to part of page.

We can reset the offset in the current sk->sk_sndmsg_page if we are the
last user of the page.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 43c490d..bf257de 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1565,6 +1565,9 @@ new_page:
        } else {
                unsigned int mlen;
 
+               /* If we are the only user of the page, we can reset offset */
+               if (page_count(p) == 1)
+                       sk->sk_sndmsg_off = 0;
                off = sk->sk_sndmsg_off;
                mlen = PAGE_SIZE - off;
                if (mlen < 64 && mlen < *len) {