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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: Tejun Heo <tj@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Jan Kara 2017-03-23 01:36:56 +01:00 committed by Jens Axboe
parent 810df54a64
commit e8cb72b322
1 changed files with 28 additions and 6 deletions
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34
mm/backing-dev.c
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@ -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));