writeback: remove vm_dirties and task->dirties

They are not used any more.
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>

include/linux/init_task.h

@@ -184,7 +184,6 @@ extern struct cred init_cred;
 		[PIDTYPE_SID]  = INIT_PID_LINK(PIDTYPE_SID),		\
 	},								\
 	.thread_group	= LIST_HEAD_INIT(tsk.thread_group),		\
-	.dirties = INIT_PROP_LOCAL_SINGLE(dirties),			\
 	INIT_IDS							\
 	INIT_PERF_EVENTS(tsk)						\
 	INIT_TRACE_IRQFLAGS						\

include/linux/sched.h

@@ -1521,7 +1521,6 @@ struct task_struct {
 #ifdef CONFIG_FAULT_INJECTION
 	int make_it_fail;
 #endif
-	struct prop_local_single dirties;
 	/*
 	 * when (nr_dirtied >= nr_dirtied_pause), it's time to call
 	 * balance_dirty_pages() for some dirty throttling pause

kernel/fork.c

@@ -162,7 +162,6 @@ static void account_kernel_stack(struct thread_info *ti, int account)
 
 void free_task(struct task_struct *tsk)
 {
-	prop_local_destroy_single(&tsk->dirties);
 	account_kernel_stack(tsk->stack, -1);
 	free_thread_info(tsk->stack);
 	rt_mutex_debug_task_free(tsk);
@@ -274,10 +273,6 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 
 	tsk->stack = ti;
 
-	err = prop_local_init_single(&tsk->dirties);
-	if (err)
-		goto out;
-
 	setup_thread_stack(tsk, orig);
 	clear_user_return_notifier(tsk);
 	clear_tsk_need_resched(tsk);

mm/page-writeback.c

@@ -128,7 +128,6 @@ unsigned long global_dirty_limit;
  *
  */
 static struct prop_descriptor vm_completions;
-static struct prop_descriptor vm_dirties;
 
 /*
  * couple the period to the dirty_ratio:
@@ -154,7 +153,6 @@ static void update_completion_period(void)
 {
 	int shift = calc_period_shift();
 	prop_change_shift(&vm_completions, shift);
-	prop_change_shift(&vm_dirties, shift);
 
 	writeback_set_ratelimit();
 }
@@ -235,11 +233,6 @@ void bdi_writeout_inc(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL_GPL(bdi_writeout_inc);
 
-void task_dirty_inc(struct task_struct *tsk)
-{
-	prop_inc_single(&vm_dirties, &tsk->dirties);
-}
-
 /*
  * Obtain an accurate fraction of the BDI's portion.
  */
@@ -1395,7 +1388,6 @@ void __init page_writeback_init(void)
 
 	shift = calc_period_shift();
 	prop_descriptor_init(&vm_completions, shift);
-	prop_descriptor_init(&vm_dirties, shift);
 }
 
 /**
@@ -1724,7 +1716,6 @@ void account_page_dirtied(struct page *page, struct address_space *mapping)
 		__inc_zone_page_state(page, NR_DIRTIED);
 		__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
 		__inc_bdi_stat(mapping->backing_dev_info, BDI_DIRTIED);
-		task_dirty_inc(current);
 		task_io_account_write(PAGE_CACHE_SIZE);
 	}
 }