net: move zerocopy_sg_from_iovec() to net/core/datagram.c

To let it be reused and reduce code duplication. Also document this function.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 0 insertions, 80 deletions

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 18527ef0cc75..b1630479d4a1 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -961,86 +961,6 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
         return skb;
 }
 
-/* set skb frags from iovec, this can move to core network code for reuse */
-static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
-                                  int offset, size_t count)
-{
-        int len = iov_length(from, count) - offset;
-        int copy = skb_headlen(skb);
-        int size, offset1 = 0;
-        int i = 0;
-
-        /* Skip over from offset */
-        while (count && (offset >= from->iov_len)) {
-                offset -= from->iov_len;
-                ++from;
-                --count;
-        }
-
-        /* copy up to skb headlen */
-        while (count && (copy > 0)) {
-                size = min_t(unsigned int, copy, from->iov_len - offset);
-                if (copy_from_user(skb->data + offset1, from->iov_base + offset,
-                                   size))
-                        return -EFAULT;
-                if (copy > size) {
-                        ++from;
-                        --count;
-                        offset = 0;
-                } else
-                        offset += size;
-                copy -= size;
-                offset1 += size;
-        }
-
-        if (len == offset1)
-                return 0;
-
-        while (count--) {
-                struct page *page[MAX_SKB_FRAGS];
-                int num_pages;
-                unsigned long base;
-                unsigned long truesize;
-
-                len = from->iov_len - offset;
-                if (!len) {
-                        offset = 0;
-                        ++from;
-                        continue;
-                }
-                base = (unsigned long)from->iov_base + offset;
-                size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
-                if (i + size > MAX_SKB_FRAGS)
-                        return -EMSGSIZE;
-                num_pages = get_user_pages_fast(base, size, 0, &page[i]);
-                if (num_pages != size) {
-                        int j;
-
-                        for (j = 0; j < num_pages; j++)
-                                put_page(page[i + j]);
-                        return -EFAULT;
-                }
-                truesize = size * PAGE_SIZE;
-                skb->data_len += len;
-                skb->len += len;
-                skb->truesize += truesize;
-                atomic_add(truesize, &skb->sk->sk_wmem_alloc);
-                while (len) {
-                        int off = base & ~PAGE_MASK;
-                        int size = min_t(int, len, PAGE_SIZE - off);
-                        __skb_fill_page_desc(skb, i, page[i], off, size);
-                        skb_shinfo(skb)->nr_frags++;
-                        /* increase sk_wmem_alloc */
-                        base += size;
-                        len -= size;
-                        i++;
-                }
-                offset = 0;
-                ++from;
-        }
-        return 0;
-}
-
 /* Get packet from user space buffer */
 static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
                             void *msg_control, const struct iovec *iv,