Re: [PATCH] nilfs2: fix backing_dev_info reference leak

[Viacheslav Dubeyko]

On Thu, 2026-05-07 at 11:50 -0400, Shuangpeng Bai wrote:
> setup_bdev_super() already initializes sb->s_bdev and takes a
> reference on the block device backing_dev_info when assigning sb->s_bdi.
> 
> nilfs_fill_super() takes another reference to the same
> backing_dev_info and stores it in sb->s_bdi again. The extra
> reference is not paired with a matching bdi_put(), since
> generic_shutdown_super() releases sb->s_bdi only once.
> 
> Drop the redundant bdi_get() in nilfs_fill_super(). The single
> reference taken by setup_bdev_super() is enough and is released
> during superblock shutdown.
> 
> Fixes: c1e012ea9e83 ("nilfs2: use setup_bdev_super to de-duplicate the mount code")
> Signed-off-by: Shuangpeng Bai <shuangpeng.kernel@xxxxxxxxx>
> ---
>  fs/nilfs2/super.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
> index 7aa5ef8606cd..893a504cb80c 100644
> --- a/fs/nilfs2/super.c
> +++ b/fs/nilfs2/super.c
> @@ -1070,8 +1070,6 @@ nilfs_fill_super(struct super_block *sb, struct fs_context *fc)
>  	sb->s_time_gran = 1;
>  	sb->s_max_links = NILFS_LINK_MAX;
>  
> -	sb->s_bdi = bdi_get(sb->s_bdev->bd_disk->bdi);
> -
>  	err = load_nilfs(nilfs, sb);
>  	if (err)
>  		goto failed_nilfs;

Makes sense to me.

Reviewed-by: Viacheslav Dubeyko <slava@xxxxxxxxxxx>

Thanks,
Slava.