Re: [PATCH 06/13] bdi: Make wb->bdi a proper reference

[Tejun Heo]

On Tue, Feb 21, 2017 at 06:09:51PM +0100, Jan Kara wrote:
> Make wb->bdi a proper refcounted reference to bdi for all bdi_writeback
> structures except for the one embedded inside struct backing_dev_info.
> That will allow us to simplify bdi unregistration.
> 
> Signed-off-by: Jan Kara 

Acked-by: Tejun Heo 

Thanks.

-- 
tejun

[PATCH 06/13] bdi: Make wb->bdi a proper reference

[Jan Kara]

Make wb->bdi a proper refcounted reference to bdi for all bdi_writeback
structures except for the one embedded inside struct backing_dev_info.
That will allow us to simplify bdi unregistration.

Signed-off-by: Jan Kara 
---
 mm/backing-dev.c | 13 +++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c324eae17f0d..d7aaf2517c30 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -294,6 +294,8 @@ static int wb_init(struct bdi_writeback *wb, struct 
backing_dev_info *bdi,
 
memset(wb, 0, sizeof(*wb));
 
+   if (wb != >wb)
+   bdi_get(bdi);
wb->bdi = bdi;
wb->last_old_flush = jiffies;
INIT_LIST_HEAD(>b_dirty);
@@ -314,8 +316,10 @@ static int wb_init(struct bdi_writeback *wb, struct 
backing_dev_info *bdi,
wb->dirty_sleep = jiffies;
 
wb->congested = wb_congested_get_create(bdi, blkcg_id, gfp);
-   if (!wb->congested)
-   return -ENOMEM;
+   if (!wb->congested) {
+   err = -ENOMEM;
+   goto out_put_bdi;
+   }
 
err = fprop_local_init_percpu(>completions, gfp);
if (err)
@@ -335,6 +339,9 @@ static int wb_init(struct bdi_writeback *wb, struct 
backing_dev_info *bdi,
fprop_local_destroy_percpu(>completions);
 out_put_cong:
wb_congested_put(wb->congested);
+out_put_bdi:
+   if (wb != >wb)
+   bdi_put(bdi);
return err;
 }
 
@@ -372,6 +379,8 @@ static void wb_exit(struct bdi_writeback *wb)
 
fprop_local_destroy_percpu(>completions);
wb_congested_put(wb->congested);
+   if (wb != >bdi->wb)
+   bdi_put(wb->bdi);
 }
 
 #ifdef CONFIG_CGROUP_WRITEBACK
-- 
2.10.2