[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>

4 files changed, 7 insertions, 10 deletions

diff --git a/net/atm/common.c b/net/atm/common.c
index 6dc12305799e..a3ca922d307b 100644
--- a/net/atm/common.c
+++ b/net/atm/common.c
@@ -630,7 +630,7 @@ int vcc_sendmsg(struct socket *sock, struct msghdr *m, size_t size)
 		goto out;
 	skb->dev = NULL; /* for paths shared with net_device interfaces */
 	ATM_SKB(skb)->atm_options = vcc->atm_options;
-	if (copy_from_iter(skb_put(skb, size), size, &m->msg_iter) != size) {
+	if (!copy_from_iter_full(skb_put(skb, size), size, &m->msg_iter)) {
 		kfree_skb(skb);
 		error = -EFAULT;
 		goto out;
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 577f1c01454a..ce0b5dd01953 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -2127,7 +2127,7 @@ static inline int l2cap_skbuff_fromiovec(struct l2cap_chan *chan,
 	struct sk_buff **frag;
 	int sent = 0;
 
-	if (copy_from_iter(skb_put(skb, count), count, &msg->msg_iter) != count)
+	if (!copy_from_iter_full(skb_put(skb, count), count, &msg->msg_iter))
 		return -EFAULT;
 
 	sent += count;
@@ -2147,8 +2147,8 @@ static inline int l2cap_skbuff_fromiovec(struct l2cap_chan *chan,
 
 		*frag = tmp;
 
-		if (copy_from_iter(skb_put(*frag, count), count,
-				   &msg->msg_iter) != count)
+		if (!copy_from_iter_full(skb_put(*frag, count), count,
+				   &msg->msg_iter))
 			return -EFAULT;
 
 		sent += count;
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);
diff --git a/net/tipc/msg.c b/net/tipc/msg.c
index 17201aa8423d..a22be502f1bd 100644
--- a/net/tipc/msg.c
+++ b/net/tipc/msg.c
@@ -268,7 +268,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
 		__skb_queue_tail(list, skb);
 		skb_copy_to_linear_data(skb, mhdr, mhsz);
 		pktpos = skb->data + mhsz;
-		if (copy_from_iter(pktpos, dsz, &m->msg_iter) == dsz)
+		if (copy_from_iter_full(pktpos, dsz, &m->msg_iter))
 			return dsz;
 		rc = -EFAULT;
 		goto error;
@@ -299,7 +299,7 @@ int tipc_msg_build(struct tipc_msg *mhdr, struct msghdr *m,
 		if (drem < pktrem)
 			pktrem = drem;
 
-		if (copy_from_iter(pktpos, pktrem, &m->msg_iter) != pktrem) {
+		if (!copy_from_iter_full(pktpos, pktrem, &m->msg_iter)) {
 			rc = -EFAULT;
 			goto error;
 		}