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new helpers: skb_copy_datagram_from_iter() and zerocopy_sg_from_iter() 

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2014-06-19 14:15:22 -04:00
parent 3af0bfe582
commit 3a654f975b
2 changed files with 119 additions and 0 deletions
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3
include/linux/skbuff.h
View File

@ -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);

116
net/core/datagram.c
View File

@ -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)