net: splice: fix __splice_segment()

[ Upstream commit bc9540c637c3d8712ccbf9dcf28621f380ed5e64 ]

commit 9ca1b22d6d2 (net: splice: avoid high order page splitting)
forgot that skb->head could need a copy into several page frags.

This could be the case for loopback traffic mostly.

Also remove now useless skb argument from linear_to_page()
and __splice_segment() prototypes.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 5b1b91582217189acaf0be4c9ac453d05298336b..1899d834c91090251d9ebe86fff56e53bf9c30bb 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1620,7 +1620,7 @@ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i)
 
 static struct page *linear_to_page(struct page *page, unsigned int *len,
                                   unsigned int *offset,
-                                  struct sk_buff *skb, struct sock *sk)
+                                  struct sock *sk)
 {
        struct page_frag *pfrag = sk_page_frag(sk);
 
@@ -1653,14 +1653,14 @@ static bool spd_can_coalesce(const struct splice_pipe_desc *spd,
 static bool spd_fill_page(struct splice_pipe_desc *spd,
                          struct pipe_inode_info *pipe, struct page *page,
                          unsigned int *len, unsigned int offset,
-                         struct sk_buff *skb, bool linear,
+                         bool linear,
                          struct sock *sk)
 {
        if (unlikely(spd->nr_pages == MAX_SKB_FRAGS))
                return true;
 
        if (linear) {
-               page = linear_to_page(page, len, &offset, skb, sk);
+               page = linear_to_page(page, len, &offset, sk);
                if (!page)
                        return true;
        }
@@ -1679,13 +1679,11 @@ static bool spd_fill_page(struct splice_pipe_desc *spd,
 
 static bool __splice_segment(struct page *page, unsigned int poff,
                             unsigned int plen, unsigned int *off,
-                            unsigned int *len, struct sk_buff *skb,
+                            unsigned int *len,
                             struct splice_pipe_desc *spd, bool linear,
                             struct sock *sk,
                             struct pipe_inode_info *pipe)
 {
-       unsigned int flen;
-
        if (!*len)
                return true;
 
@@ -1700,12 +1698,16 @@ static bool __splice_segment(struct page *page, unsigned int poff,
        plen -= *off;
        *off = 0;
 
-       flen = min(*len, plen);
-
-       if (spd_fill_page(spd, pipe, page, &flen, poff, skb, linear, sk))
-               return true;
+       do {
+               unsigned int flen = min(*len, plen);
 
-       *len -= flen;
+               if (spd_fill_page(spd, pipe, page, &flen, poff,
+                                 linear, sk))
+                       return true;
+               poff += flen;
+               plen -= flen;
+               *len -= flen;
+       } while (*len && plen);
 
        return false;
 }
@@ -1728,7 +1730,7 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
        if (__splice_segment(virt_to_page(skb->data),
                             (unsigned long) skb->data & (PAGE_SIZE - 1),
                             skb_headlen(skb),
-                            offset, len, skb, spd,
+                            offset, len, spd,
                             skb_head_is_locked(skb),
                             sk, pipe))
                return true;
@@ -1741,7 +1743,7 @@ static bool __skb_splice_bits(struct sk_buff *skb, struct pipe_inode_info *pipe,
 
                if (__splice_segment(skb_frag_page(f),
                                     f->page_offset, skb_frag_size(f),
-                                    offset, len, skb, spd, false, sk, pipe))
+                                    offset, len, spd, false, sk, pipe))
                        return true;
        }