rxrpc: Fix call interruptibility handling

Fix the interruptibility of kernel-initiated client calls so that they're
either only interruptible when they're waiting for a call slot to come
available or they're not interruptible at all.  Either way, they're not
interruptible during transmission.

This should help prevent StoreData calls from being interrupted when
writeback is in progress.  It doesn't, however, handle interruption during
the receive phase.

Userspace-initiated calls are still interruptable.  After the signal has
been handled, sendmsg() will return the amount of data copied out of the
buffer and userspace can perform another sendmsg() call to continue
transmission.

Fixes: bc5e3a546d ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/ar-internal.h

@@ -489,7 +489,6 @@ enum rxrpc_call_flag {
 	RXRPC_CALL_BEGAN_RX_TIMER,	/* We began the expect_rx_by timer */
 	RXRPC_CALL_RX_HEARD,		/* The peer responded at least once to this call */
 	RXRPC_CALL_RX_UNDERRUN,		/* Got data underrun */
-	RXRPC_CALL_IS_INTR,		/* The call is interruptible */
 	RXRPC_CALL_DISCONNECTED,	/* The call has been disconnected */
 };
 
@@ -598,6 +597,7 @@ struct rxrpc_call {
 	atomic_t		usage;
 	u16			service_id;	/* service ID */
 	u8			security_ix;	/* Security type */
+	enum rxrpc_interruptibility interruptibility; /* At what point call may be interrupted */
 	u32			call_id;	/* call ID on connection  */
 	u32			cid;		/* connection ID plus channel index */
 	int			debug_id;	/* debug ID for printks */
@@ -721,7 +721,7 @@ struct rxrpc_call_params {
 		u32		normal;		/* Max time since last call packet (msec) */
 	} timeouts;
 	u8			nr_timeouts;	/* Number of timeouts specified */
-	bool			intr;		/* The call is interruptible */
+	enum rxrpc_interruptibility interruptibility; /* How is interruptible is the call? */
 };
 
 struct rxrpc_send_params {