smc: add support for splice()

Provide an implementation for splice() when we are using SMC. See
smc_splice_read() for further details.

Signed-off-by: Stefan Raspl <raspl@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com><
Signed-off-by: David S. Miller <davem@davemloft.net>

net/smc/smc.h

@@ -164,6 +164,9 @@ struct smc_connection {
 	atomic_t		bytes_to_rcv;	/* arrived data,
 						 * not yet received
 						 */
+	atomic_t		splice_pending;	/* number of spliced bytes
+						 * pending processing
+						 */
 #ifndef KERNEL_HAS_ATOMIC64
 	spinlock_t		acurs_lock;	/* protect cursors */
 #endif