new helpers: skb_copy_datagram_from_iter() and zerocopy_sg_from_iter()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index d048347a010a5a50c5c00894fda4cadbba8f08ab..a01cd9ad0b516ea560ed6209d87c1d014c1a1be6 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2659,10 +2659,13 @@ static inline int skb_copy_and_csum_datagram_msg(struct sk_buff *skb, int hlen,
 int skb_copy_datagram_from_iovec(struct sk_buff *skb, int offset,
                                 const struct iovec *from, int from_offset,
                                 int len);
+int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
+                                struct iov_iter *from, int len);
 int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
                           int offset, size_t count);
 int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
                           struct iov_iter *to, int size);
+int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *frm);
 void skb_free_datagram(struct sock *sk, struct sk_buff *skb);
 void skb_free_datagram_locked(struct sock *sk, struct sk_buff *skb);
 int skb_kill_datagram(struct sock *sk, struct sk_buff *skb, unsigned int flags);

diff --git a/net/core/datagram.c b/net/core/datagram.c
index 26391a3fe3e5b384cd8b87ba5d41d9f16eaf42c4..3ea038431ceb1eb93bfddb45c1447ab1e7a01cc3 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -572,6 +572,78 @@ fault:
 }
 EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
 
+int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
+                                struct iov_iter *from,
+                                int len)
+{
+       int start = skb_headlen(skb);
+       int i, copy = start - offset;
+       struct sk_buff *frag_iter;
+
+       /* Copy header. */
+       if (copy > 0) {
+               if (copy > len)
+                       copy = len;
+               if (copy_from_iter(skb->data + offset, copy, from) != copy)
+                       goto fault;
+               if ((len -= copy) == 0)
+                       return 0;
+               offset += copy;
+       }
+
+       /* Copy paged appendix. Hmm... why does this look so complicated? */
+       for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+               int end;
+               const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+               WARN_ON(start > offset + len);
+
+               end = start + skb_frag_size(frag);
+               if ((copy = end - offset) > 0) {
+                       size_t copied;
+
+                       if (copy > len)
+                               copy = len;
+                       copied = copy_page_from_iter(skb_frag_page(frag),
+                                         frag->page_offset + offset - start,
+                                         copy, from);
+                       if (copied != copy)
+                               goto fault;
+
+                       if (!(len -= copy))
+                               return 0;
+                       offset += copy;
+               }
+               start = end;
+       }
+
+       skb_walk_frags(skb, frag_iter) {
+               int end;
+
+               WARN_ON(start > offset + len);
+
+               end = start + frag_iter->len;
+               if ((copy = end - offset) > 0) {
+                       if (copy > len)
+                               copy = len;
+                       if (skb_copy_datagram_from_iter(frag_iter,
+                                                       offset - start,
+                                                       from, copy))
+                               goto fault;
+                       if ((len -= copy) == 0)
+                               return 0;
+                       offset += copy;
+               }
+               start = end;
+       }
+       if (!len)
+               return 0;
+
+fault:
+       return -EFAULT;
+}
+EXPORT_SYMBOL(skb_copy_datagram_from_iter);
+
 /**
  *     zerocopy_sg_from_iovec - Build a zerocopy datagram from an iovec
  *     @skb: buffer to copy
@@ -643,6 +715,50 @@ int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
 }
 EXPORT_SYMBOL(zerocopy_sg_from_iovec);
 
+int zerocopy_sg_from_iter(struct sk_buff *skb, struct iov_iter *from)
+{
+       int len = iov_iter_count(from);
+       int copy = min_t(int, skb_headlen(skb), len);
+       int frag = 0;
+
+       /* copy up to skb headlen */
+       if (skb_copy_datagram_from_iter(skb, 0, from, copy))
+               return -EFAULT;
+
+       while (iov_iter_count(from)) {
+               struct page *pages[MAX_SKB_FRAGS];
+               size_t start;
+               ssize_t copied;
+               unsigned long truesize;
+               int n = 0;
+
+               if (frag == MAX_SKB_FRAGS)
+                       return -EMSGSIZE;
+
+               copied = iov_iter_get_pages(from, pages, ~0U,
+                                           MAX_SKB_FRAGS - frag, &start);
+               if (copied < 0)
+                       return -EFAULT;
+
+               iov_iter_advance(from, copied);
+
+               truesize = PAGE_ALIGN(copied + start);
+               skb->data_len += copied;
+               skb->len += copied;
+               skb->truesize += truesize;
+               atomic_add(truesize, &skb->sk->sk_wmem_alloc);
+               while (copied) {
+                       int size = min_t(int, copied, PAGE_SIZE - start);
+                       skb_fill_page_desc(skb, frag++, pages[n], start, size);
+                       start = 0;
+                       copied -= size;
+                       n++;
+               }
+       }
+       return 0;
+}
+EXPORT_SYMBOL(zerocopy_sg_from_iter);
+
 static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
                                      u8 __user *to, int len,
                                      __wsum *csump)