Freezer / sunrpc / NFS: don't allow TASK_KILLABLE sleeps to block the freezer

Allow the freezer to skip wait_on_bit_killable sleeps in the sunrpc
layer. This should allow suspend and hibernate events to proceed, even
when there are RPC's pending on the wire.

Also, wrap the TASK_KILLABLE sleeps in NFS layer in freezer_do_not_count
and freezer_count calls. This allows the freezer to skip tasks that are
sleeping while looping on EJUKEBOX or NFS4ERR_DELAY sorts of errors.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

include/linux/freezer.h

@@ -104,6 +104,29 @@ static inline int freezer_should_skip(struct task_struct *p)
 	return !!(p->flags & PF_FREEZER_SKIP);
 }
 
+/*
+ * These macros are intended to be used whenever you want allow a task that's
+ * sleeping in TASK_UNINTERRUPTIBLE or TASK_KILLABLE state to be frozen. Note
+ * that neither return any clear indication of whether a freeze event happened
+ * while in this function.
+ */
+
+/* Like schedule(), but should not block the freezer. */
+#define freezable_schedule()						\
+({									\
+	freezer_do_not_count();						\
+	schedule();							\
+	freezer_count();						\
+})
+
+/* Like schedule_timeout_killable(), but should not block the freezer. */
+#define freezable_schedule_timeout_killable(timeout)			\
+({									\
+	freezer_do_not_count();						\
+	schedule_timeout_killable(timeout);				\
+	freezer_count();						\
+})
+
 /*
  * Freezer-friendly wrappers around wait_event_interruptible(),
  * wait_event_killable() and wait_event_interruptible_timeout(), originally
@@ -163,6 +186,11 @@ static inline void freezer_count(void) {}
 static inline int freezer_should_skip(struct task_struct *p) { return 0; }
 static inline void set_freezable(void) {}
 
+#define freezable_schedule()  schedule()
+
+#define freezable_schedule_timeout_killable(timeout)			\
+	schedule_timeout_killable(timeout)
+
 #define wait_event_freezable(wq, condition)				\
 		wait_event_interruptible(wq, condition)