net: splice: fix __splice_segment()

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>

1 files changed, 15 insertions, 13 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 1e1b9ea0296d..2568c449fe36 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1652,7 +1652,7 @@ 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);
 
@@ -1685,14 +1685,14 @@ 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;
         }
@@ -1711,13 +1711,11 @@ 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;
 
@@ -1732,12 +1730,16 @@ 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;
 }
@@ -1760,7 +1762,7 @@ 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;
@@ -1773,7 +1775,7 @@ 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;
         }