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Commit e8cb72b3 authored by Jan Kara's avatar Jan Kara Committed by Jens Axboe
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bdi: Unify bdi->wb_list handling for root wb_writeback 



Currently root wb_writeback structure is added to bdi->wb_list in
bdi_init() and never removed. That is different from all other
wb_writeback structures which get added to the list when created and
removed from it before wb_shutdown().

So move list addition of root bdi_writeback to bdi_register() and list
removal of all wb_writeback structures to wb_shutdown(). That way a
wb_writeback structure is on bdi->wb_list if and only if it can handle
writeback and it will make it easier for us to handle shutdown of all
wb_writeback structures in bdi_unregister().

Acked-by: default avatarTejun Heo <tj@kernel.org>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 810df54a

mm/backing-dev.c

+28 −6
Original line number Diff line number Diff line
@@ -345,6 +345,8 @@ static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi, 
	return err;

}



static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb);



/*

 * Remove bdi from the global list and shutdown any threads we have running

 */
@@ -358,6 +360,7 @@ static void wb_shutdown(struct bdi_writeback *wb) 
	}

	spin_unlock_bh(&wb->work_lock);



	cgwb_remove_from_bdi_list(wb);

	/*

	 * Drain work list and shutdown the delayed_work.  !WB_registered

	 * tells wb_workfn() that @wb is dying and its work_list needs to
@@ -491,10 +494,6 @@ static void cgwb_release_workfn(struct work_struct *work) 
						release_work);

	struct backing_dev_info *bdi = wb->bdi;



	spin_lock_irq(&cgwb_lock);

	list_del_rcu(&wb->bdi_node);

	spin_unlock_irq(&cgwb_lock);



	wb_shutdown(wb);



	css_put(wb->memcg_css);
@@ -526,6 +525,13 @@ static void cgwb_kill(struct bdi_writeback *wb) 
	percpu_ref_kill(&wb->refcnt);

}



static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)

{

	spin_lock_irq(&cgwb_lock);

	list_del_rcu(&wb->bdi_node);

	spin_unlock_irq(&cgwb_lock);

}



static int cgwb_create(struct backing_dev_info *bdi,

		       struct cgroup_subsys_state *memcg_css, gfp_t gfp)

{
@@ -766,6 +772,13 @@ static void cgwb_bdi_exit(struct backing_dev_info *bdi) 
	spin_unlock_irq(&cgwb_lock);

}



static void cgwb_bdi_register(struct backing_dev_info *bdi)

{

	spin_lock_irq(&cgwb_lock);

	list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);

	spin_unlock_irq(&cgwb_lock);

}



#else	/* CONFIG_CGROUP_WRITEBACK */



static int cgwb_bdi_init(struct backing_dev_info *bdi)
@@ -793,6 +806,16 @@ static void cgwb_bdi_exit(struct backing_dev_info *bdi) 
	wb_congested_put(bdi->wb_congested);

}



static void cgwb_bdi_register(struct backing_dev_info *bdi)

{

	list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);

}



static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb)

{

	list_del_rcu(&wb->bdi_node);

}



#endif	/* CONFIG_CGROUP_WRITEBACK */



int bdi_init(struct backing_dev_info *bdi)
@@ -811,8 +834,6 @@ int bdi_init(struct backing_dev_info *bdi) 


	ret = cgwb_bdi_init(bdi);



	list_add_tail_rcu(&bdi->wb.bdi_node, &bdi->wb_list);



	return ret;

}

EXPORT_SYMBOL(bdi_init);
@@ -848,6 +869,7 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, 
	if (IS_ERR(dev))

		return PTR_ERR(dev);



	cgwb_bdi_register(bdi);

	bdi->dev = dev;



	bdi_debug_register(bdi, dev_name(dev));