From: Eric Dumazet <edumazet@google.com>
Date: Thu, 19 Apr 2012 09:38:17 +0000 (+0000)
Subject: net: allow better page reuse in splice(sock -> pipe)
X-Git-Tag: v3.5-rc1~109^2~323
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e66e9a31474dcce5be6f1186dc933d8a991c707b;p=profile%2Fivi%2Fkernel-adaptation-intel-automotive.git

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
--- 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) {