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>
This commit is contained in:
Jason Wang
David S. Miller
Родитель
b4bf07771f
Коммит
c3bdeb5c7c
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@ -536,86 +536,6 @@ static inline struct sk_buff *macvtap_alloc_skb(struct sock *sk, size_t prepad,
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return skb;
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}
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/* set skb frags from iovec, this can move to core network code for reuse */
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static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
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int offset, size_t count)
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{
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int len = iov_length(from, count) - offset;
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int copy = skb_headlen(skb);
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int size, offset1 = 0;
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int i = 0;
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/* Skip over from offset */
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while (count && (offset >= from->iov_len)) {
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offset -= from->iov_len;
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++from;
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--count;
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}
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/* copy up to skb headlen */
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while (count && (copy > 0)) {
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size = min_t(unsigned int, copy, from->iov_len - offset);
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if (copy_from_user(skb->data + offset1, from->iov_base + offset,
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size))
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return -EFAULT;
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if (copy > size) {
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++from;
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--count;
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offset = 0;
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} else
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offset += size;
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copy -= size;
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offset1 += size;
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}
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if (len == offset1)
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return 0;
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while (count--) {
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struct page *page[MAX_SKB_FRAGS];
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int num_pages;
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unsigned long base;
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unsigned long truesize;
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len = from->iov_len - offset;
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if (!len) {
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offset = 0;
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++from;
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continue;
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}
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base = (unsigned long)from->iov_base + offset;
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size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
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if (i + size > MAX_SKB_FRAGS)
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return -EMSGSIZE;
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num_pages = get_user_pages_fast(base, size, 0, &page[i]);
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if (num_pages != size) {
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int j;
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for (j = 0; j < num_pages; j++)
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put_page(page[i + j]);
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return -EFAULT;
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}
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truesize = size * PAGE_SIZE;
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skb->data_len += len;
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skb->len += len;
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skb->truesize += truesize;
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atomic_add(truesize, &skb->sk->sk_wmem_alloc);
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while (len) {
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int off = base & ~PAGE_MASK;
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int size = min_t(int, len, PAGE_SIZE - off);
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__skb_fill_page_desc(skb, i, page[i], off, size);
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skb_shinfo(skb)->nr_frags++;
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/* increase sk_wmem_alloc */
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base += size;
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len -= size;
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i++;
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}
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offset = 0;
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++from;
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}
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return 0;
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}
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/*
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* macvtap_skb_from_vnet_hdr and macvtap_skb_to_vnet_hdr should
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* be shared with the tun/tap driver.
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@ -961,86 +961,6 @@ static struct sk_buff *tun_alloc_skb(struct tun_file *tfile,
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return skb;
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}
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/* set skb frags from iovec, this can move to core network code for reuse */
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static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
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int offset, size_t count)
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{
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int len = iov_length(from, count) - offset;
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int copy = skb_headlen(skb);
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int size, offset1 = 0;
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int i = 0;
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/* Skip over from offset */
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while (count && (offset >= from->iov_len)) {
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offset -= from->iov_len;
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++from;
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--count;
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}
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/* copy up to skb headlen */
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while (count && (copy > 0)) {
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size = min_t(unsigned int, copy, from->iov_len - offset);
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if (copy_from_user(skb->data + offset1, from->iov_base + offset,
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size))
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return -EFAULT;
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if (copy > size) {
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++from;
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--count;
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offset = 0;
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} else
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offset += size;
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copy -= size;
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offset1 += size;
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}
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if (len == offset1)
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return 0;
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while (count--) {
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struct page *page[MAX_SKB_FRAGS];
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int num_pages;
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unsigned long base;
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unsigned long truesize;
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len = from->iov_len - offset;
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if (!len) {
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offset = 0;
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++from;
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continue;
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}
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base = (unsigned long)from->iov_base + offset;
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size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
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if (i + size > MAX_SKB_FRAGS)
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return -EMSGSIZE;
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num_pages = get_user_pages_fast(base, size, 0, &page[i]);
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if (num_pages != size) {
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int j;
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for (j = 0; j < num_pages; j++)
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put_page(page[i + j]);
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return -EFAULT;
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}
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truesize = size * PAGE_SIZE;
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skb->data_len += len;
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skb->len += len;
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skb->truesize += truesize;
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atomic_add(truesize, &skb->sk->sk_wmem_alloc);
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while (len) {
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int off = base & ~PAGE_MASK;
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int size = min_t(int, len, PAGE_SIZE - off);
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__skb_fill_page_desc(skb, i, page[i], off, size);
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skb_shinfo(skb)->nr_frags++;
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/* increase sk_wmem_alloc */
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base += size;
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len -= size;
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i++;
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}
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offset = 0;
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++from;
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}
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return 0;
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}
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/* Get packet from user space buffer */
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static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
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void *msg_control, const struct iovec *iv,
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@ -2359,6 +2359,10 @@ extern int skb_copy_datagram_from_iovec(struct sk_buff *skb,
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const struct iovec *from,
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int from_offset,
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int len);
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extern int zerocopy_sg_from_iovec(struct sk_buff *skb,
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const struct iovec *frm,
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int offset,
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size_t count);
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extern int skb_copy_datagram_const_iovec(const struct sk_buff *from,
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int offset,
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const struct iovec *to,
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@ -573,6 +573,99 @@ fault:
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}
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EXPORT_SYMBOL(skb_copy_datagram_from_iovec);
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/**
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* zerocopy_sg_from_iovec - Build a zerocopy datagram from an iovec
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* @skb: buffer to copy
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* @from: io vector to copy to
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* @offset: offset in the io vector to start copying from
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* @count: amount of vectors to copy to buffer from
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*
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* The function will first copy up to headlen, and then pin the userspace
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* pages and build frags through them.
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*
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* Returns 0, -EFAULT or -EMSGSIZE.
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* Note: the iovec is not modified during the copy
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*/
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int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from,
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int offset, size_t count)
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{
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int len = iov_length(from, count) - offset;
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int copy = skb_headlen(skb);
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int size, offset1 = 0;
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int i = 0;
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/* Skip over from offset */
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while (count && (offset >= from->iov_len)) {
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offset -= from->iov_len;
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++from;
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--count;
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}
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/* copy up to skb headlen */
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while (count && (copy > 0)) {
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size = min_t(unsigned int, copy, from->iov_len - offset);
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if (copy_from_user(skb->data + offset1, from->iov_base + offset,
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size))
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return -EFAULT;
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if (copy > size) {
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++from;
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--count;
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offset = 0;
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} else
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offset += size;
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copy -= size;
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offset1 += size;
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}
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if (len == offset1)
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return 0;
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while (count--) {
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struct page *page[MAX_SKB_FRAGS];
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int num_pages;
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unsigned long base;
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unsigned long truesize;
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len = from->iov_len - offset;
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if (!len) {
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offset = 0;
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++from;
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continue;
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}
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base = (unsigned long)from->iov_base + offset;
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size = ((base & ~PAGE_MASK) + len + ~PAGE_MASK) >> PAGE_SHIFT;
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if (i + size > MAX_SKB_FRAGS)
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return -EMSGSIZE;
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num_pages = get_user_pages_fast(base, size, 0, &page[i]);
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if (num_pages != size) {
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int j;
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for (j = 0; j < num_pages; j++)
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put_page(page[i + j]);
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return -EFAULT;
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}
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truesize = size * PAGE_SIZE;
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skb->data_len += len;
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skb->len += len;
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skb->truesize += truesize;
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atomic_add(truesize, &skb->sk->sk_wmem_alloc);
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while (len) {
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int off = base & ~PAGE_MASK;
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int size = min_t(int, len, PAGE_SIZE - off);
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__skb_fill_page_desc(skb, i, page[i], off, size);
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skb_shinfo(skb)->nr_frags++;
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/* increase sk_wmem_alloc */
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base += size;
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len -= size;
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i++;
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}
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offset = 0;
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++from;
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}
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return 0;
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}
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EXPORT_SYMBOL(zerocopy_sg_from_iovec);
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static int skb_copy_and_csum_datagram(const struct sk_buff *skb, int offset,
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u8 __user *to, int len,
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__wsum *csump)
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