inet: Add skb_copy_datagram_iter

This patch adds skb_copy_datagram_iter, which is identical to
skb_copy_datagram_iovec except that it operates on iov_iter
instead of iovec.

Eventually all users of skb_copy_datagram_iovec should switch
over to iov_iter and then we can remove skb_copy_datagram_iovec.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 53f4f6c..933cfce 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -150,6 +150,7 @@
 struct net_device;
 struct scatterlist;
 struct pipe_inode_info;
+struct iov_iter;
 
 #if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
 struct nf_conntrack {
@@ -2653,6 +2654,8 @@ int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *frm,
 int skb_copy_datagram_const_iovec(const struct sk_buff *from, int offset,
                                  const struct iovec *to, int to_offset,
                                  int size);
+int skb_copy_datagram_iter(const struct sk_buff *from, int offset,
+                          struct iov_iter *to, int size);
 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 fdbc9a8..84d90d0 100644 (file)
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -49,6 +49,7 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/pagemap.h>
+#include <linux/uio.h>
 
 #include <net/protocol.h>
 #include <linux/skbuff.h>
@@ -481,6 +482,92 @@ fault:
 }
 EXPORT_SYMBOL(skb_copy_datagram_const_iovec);
 
+/**
+ *     skb_copy_datagram_iter - Copy a datagram to an iovec iterator.
+ *     @skb: buffer to copy
+ *     @offset: offset in the buffer to start copying from
+ *     @to: iovec iterator to copy to
+ *     @len: amount of data to copy from buffer to iovec
+ */
+int skb_copy_datagram_iter(const struct sk_buff *skb, int offset,
+                          struct iov_iter *to, int len)
+{
+       int start = skb_headlen(skb);
+       int i, copy = start - offset;
+       struct sk_buff *frag_iter;
+
+       trace_skb_copy_datagram_iovec(skb, len);
+
+       /* Copy header. */
+       if (copy > 0) {
+               if (copy > len)
+                       copy = len;
+               if (copy_to_iter(skb->data + offset, copy, to) != copy)
+                       goto short_copy;
+               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) {
+                       if (copy > len)
+                               copy = len;
+                       if (copy_page_to_iter(skb_frag_page(frag),
+                                             frag->page_offset + offset -
+                                             start, copy, to) != copy)
+                               goto short_copy;
+                       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_iter(frag_iter, offset - start,
+                                                  to, copy))
+                               goto fault;
+                       if ((len -= copy) == 0)
+                               return 0;
+                       offset += copy;
+               }
+               start = end;
+       }
+       if (!len)
+               return 0;
+
+       /* This is not really a user copy fault, but rather someone
+        * gave us a bogus length on the skb.  We should probably
+        * print a warning here as it may indicate a kernel bug.
+        */
+
+fault:
+       return -EFAULT;
+
+short_copy:
+       if (iov_iter_count(to))
+               goto fault;
+
+       return 0;
+}
+EXPORT_SYMBOL(skb_copy_datagram_iter);
+
 /**
  *     skb_copy_datagram_from_iovec - Copy a datagram from an iovec.
  *     @skb: buffer to copy