Re: [PATCH 3/4] bdi: add error handle for bdi_debug_register

[Jan Kara <jack@suse.cz>]

On Fri 27-10-17 01:36:14, weiping zhang wrote:
> In order to make error handle more cleaner we call bdi_debug_register
> before set state to WB_registered, that we can avoid call bdi_unregister
> in release_bdi().
> 
> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com>
> ---
>  mm/backing-dev.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> index e9d6a1ede12b..54396d53f471 100644
> --- a/mm/backing-dev.c
> +++ b/mm/backing-dev.c
> @@ -893,10 +893,13 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args)
>  	if (IS_ERR(dev))
>  		return PTR_ERR(dev);
>  
> +	if (bdi_debug_register(bdi, dev_name(dev))) {
> +		device_destroy(bdi_class, dev->devt);
> +		return -ENOMEM;
> +	}
>  	cgwb_bdi_register(bdi);
>  	bdi->dev = dev;
>  
> -	bdi_debug_register(bdi, dev_name(dev));
>  	set_bit(WB_registered, &bdi->wb.state);
>  
>  	spin_lock_bh(&bdi_lock);
> @@ -916,6 +919,8 @@ int bdi_register(struct backing_dev_info *bdi, const char *fmt, ...)
>  	va_start(args, fmt);
>  	ret = bdi_register_va(bdi, fmt, args);
>  	va_end(args);
> +	if (ret)
> +		bdi_put(bdi);

Why do you drop bdi reference here in case of error? We didn't do it
previously if bdi_register_va() failed for other reasons...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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