[iov_iter] new primitives - copy_from_iter_full() and friends

copy_from_iter_full(), copy_from_iter_full_nocache() and
csum_and_copy_from_iter_full() - counterparts of copy_from_iter()
et.al., advancing iterator only in case of successful full copy
and returning whether it had been successful or not.

Convert some obvious users.  *NOTE* - do not blindly assume that
something is a good candidate for those unless you are sure that
not advancing iov_iter in failure case is the right thing in
this case.  Anything that does short read/short write kind of
stuff (or is in a loop, etc.) is unlikely to be a good one.

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

1 files changed, 1 insertions, 4 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d2238b204691..588ec202d5ba 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2432,14 +2432,11 @@ static int __packet_snd_vnet_parse(struct virtio_net_hdr *vnet_hdr, size_t len)
 static int packet_snd_vnet_parse(struct msghdr *msg, size_t *len,
 				 struct virtio_net_hdr *vnet_hdr)
 {
-	int n;
-
 	if (*len < sizeof(*vnet_hdr))
 		return -EINVAL;
 	*len -= sizeof(*vnet_hdr);
 
-	n = copy_from_iter(vnet_hdr, sizeof(*vnet_hdr), &msg->msg_iter);
-	if (n != sizeof(*vnet_hdr))
+	if (!copy_from_iter_full(vnet_hdr, sizeof(*vnet_hdr), &msg->msg_iter))
 		return -EFAULT;
 
 	return __packet_snd_vnet_parse(vnet_hdr, *len);