[PATCH] sparse: beginning of iovec cleanups - infrastructure

Beginning of iovec cleanups - added two helpers (kernel_{send,recv}msg)
that do sock_sendmsg/sock_recvmsg with kvec instead of iovec; basically,
they were abstracted from earlier afs patch.  They take kvec/length of
kvec as separate arguments, do set_fs(), stick kvec into msghdr and call
sock_...msg(). 

The next group of patches will switch network filesystems to use of kvec
for kernel data + use of these helpers.  Basically, the same thing we'd
done for afs.

include/linux/net.h

@@ -142,6 +142,7 @@ struct net_proto_family {
 };
 
 struct iovec;
+struct kvec;
 
 extern int	     sock_wake_async(struct socket *sk, int how, int band);
 extern int	     sock_register(struct net_proto_family *fam);
@@ -169,6 +170,12 @@ extern int	     net_ratelimit(void);
 extern unsigned long net_random(void);
 extern void	     net_srandom(unsigned long);
 
+extern int   	     kernel_sendmsg(struct socket *sock, struct msghdr *msg,
+				    struct kvec *vec, size_t num, size_t len);
+extern int   	     kernel_recvmsg(struct socket *sock, struct msghdr *msg,
+				    struct kvec *vec, size_t num,
+				    size_t len, int flags);
+
 #ifndef CONFIG_SMP
 #define SOCKOPS_WRAPPED(name) name
 #define SOCKOPS_WRAP(name, fam)

net/socket.c

@@ -559,6 +559,23 @@ int sock_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	return ret;
 }
 
+int kernel_sendmsg(struct socket *sock, struct msghdr *msg,
+		   struct kvec *vec, size_t num, size_t size)
+{
+	mm_segment_t oldfs = get_fs();
+	int result;
+
+	set_fs(KERNEL_DS);
+	/*
+	 * the following is safe, since for compiler definitions of kvec and
+	 * iovec are identical, yielding the same in-core layout and alignment
+	 */
+	msg->msg_iov = (struct iovec *)vec,
+	msg->msg_iovlen = num;
+	result = sock_sendmsg(sock, msg, size);
+	set_fs(oldfs);
+	return result;
+}
 
 static inline int __sock_recvmsg(struct kiocb *iocb, struct socket *sock, 
 				 struct msghdr *msg, size_t size, int flags)
@@ -594,6 +611,25 @@ int sock_recvmsg(struct socket *sock, struct msghdr *msg,
 	return ret;
 }
 
+int kernel_recvmsg(struct socket *sock, struct msghdr *msg, 
+		   struct kvec *vec, size_t num,
+		   size_t size, int flags)
+{
+	mm_segment_t oldfs = get_fs();
+	int result;
+
+	set_fs(KERNEL_DS);
+	/*
+	 * the following is safe, since for compiler definitions of kvec and
+	 * iovec are identical, yielding the same in-core layout and alignment
+	 */
+	msg->msg_iov = (struct iovec *)vec,
+	msg->msg_iovlen = num;
+	result = sock_recvmsg(sock, msg, size, flags);
+	set_fs(oldfs);
+	return result;
+}
+
 static void sock_aio_dtor(struct kiocb *iocb)
 {
 	kfree(iocb->private);
@@ -2069,3 +2105,5 @@ EXPORT_SYMBOL(sock_sendmsg);
 EXPORT_SYMBOL(sock_unregister);
 EXPORT_SYMBOL(sock_wake_async);
 EXPORT_SYMBOL(sockfd_lookup);
+EXPORT_SYMBOL(kernel_sendmsg);
+EXPORT_SYMBOL(kernel_recvmsg);