Re: [PATCH 3/5] fs: explicitly unregister per-superblock BDIs

[Jan Kara <jack@suse.cz>]

On Thu 21-10-21 14:44:39, Christoph Hellwig wrote:
> Add a new SB_I_ flag to mark superblocks that have an ephemeral bdi
> associated with them, an unregister it when the superblock is shut down.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

								Honza

> ---
>  fs/super.c         | 3 +++
>  include/linux/fs.h | 1 +
>  2 files changed, 4 insertions(+)
> 
> diff --git a/fs/super.c b/fs/super.c
> index bcef3a6f4c4b5..3bfc0f8fbd5bc 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -476,6 +476,8 @@ void generic_shutdown_super(struct super_block *sb)
>  	spin_unlock(&sb_lock);
>  	up_write(&sb->s_umount);
>  	if (sb->s_bdi != &noop_backing_dev_info) {
> +		if (sb->s_iflags & SB_I_PERSB_BDI)
> +			bdi_unregister(sb->s_bdi);
>  		bdi_put(sb->s_bdi);
>  		sb->s_bdi = &noop_backing_dev_info;
>  	}
> @@ -1562,6 +1564,7 @@ int super_setup_bdi_name(struct super_block *sb, char *fmt, ...)
>  	}
>  	WARN_ON(sb->s_bdi != &noop_backing_dev_info);
>  	sb->s_bdi = bdi;
> +	sb->s_iflags |= SB_I_PERSB_BDI;
>  
>  	return 0;
>  }
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index e7a633353fd20..226de651f52e6 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1443,6 +1443,7 @@ extern int send_sigurg(struct fown_struct *fown);
>  #define SB_I_UNTRUSTED_MOUNTER		0x00000040
>  
>  #define SB_I_SKIP_SYNC	0x00000100	/* Skip superblock at global sync */
> +#define SB_I_PERSB_BDI	0x00000200	/* has a per-sb bdi */
>  
>  /* Possible states of 'frozen' field */
>  enum {
> -- 
> 2.30.2
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR