[PATCH v2 04/35] fs: super: consolidate the get_super class functions

[Jan Kara]

On Thu 30-07-15 13:48:00, Dongsheng Yang wrote:
> There is a lot of duplicated code in get_super and user_get_super.
> This commit introduc a __get_super as a common function to reduce
> the duplication of it.
> 
> Signed-off-by: Dongsheng Yang <yangds.fnst at cn.fujitsu.com>

The patch looks good to me. You can add:

Reviewed-by: Jan Kara <jack at suse.com>

								Honza

> ---
>  fs/super.c | 64 ++++++++++++++++++++++++++++++--------------------------------
>  1 file changed, 31 insertions(+), 33 deletions(-)
> 
> diff --git a/fs/super.c b/fs/super.c
> index fadb677..46fd1f1 100644
> --- a/fs/super.c
> +++ b/fs/super.c
> @@ -559,19 +559,20 @@ void iterate_supers_type(struct file_system_type *type,
>  }
>  EXPORT_SYMBOL(iterate_supers_type);
>  
> -/**
> - * get_super - get the superblock of a device
> - * @bdev: device to get the superblock for
> - * 
> - * Scans the superblock list and finds the superblock of the file system
> - * mounted on the device given. %NULL is returned if no match is found.
> +/*
> + * __get_super - helper function for the other functions in get_super class
> + * @compare: function pointer to compare sb in list and key
> + * @key: key of the sb you want
> + *
> + * Scans the superblock list and finds the superblock you want. %NULL is
> + * returned if no match is found.
>   */
> -
> -struct super_block *get_super(struct block_device *bdev)
> +static struct super_block *__get_super(
> +		int (*compare)(struct super_block *, void *), void *key)
>  {
>  	struct super_block *sb;
>  
> -	if (!bdev)
> +	if (!key)
>  		return NULL;
>  
>  	spin_lock(&sb_lock);
> @@ -579,7 +580,7 @@ rescan:
>  	list_for_each_entry(sb, &super_blocks, s_list) {
>  		if (hlist_unhashed(&sb->s_instances))
>  			continue;
> -		if (sb->s_bdev == bdev) {
> +		if (compare(sb, key)) {
>  			sb->s_count++;
>  			spin_unlock(&sb_lock);
>  			down_read(&sb->s_umount);
> @@ -596,6 +597,20 @@ rescan:
>  	spin_unlock(&sb_lock);
>  	return NULL;
>  }
> +
> +static int bdev_compare(struct super_block *sb, void *key)
> +{
> +	return (sb->s_bdev == (struct block_device *)key);
> +}
> +
> +/**
> + * get_super - get the superblock of a device
> + * @bdev: device to get the superblock for
> + */
> +struct super_block *get_super(struct block_device *bdev)
> +{
> +	return __get_super(bdev_compare, bdev);
> +}
>  EXPORT_SYMBOL(get_super);
>  
>  /**
> @@ -651,32 +666,15 @@ restart:
>  	spin_unlock(&sb_lock);
>  	return NULL;
>  }
> +
> +static int user_compare(struct super_block *sb, void *key)
> +{
> +	return (sb->s_dev == *(dev_t *)key);
> +}
>   
>  struct super_block *user_get_super(dev_t dev)
>  {
> -	struct super_block *sb;
> -
> -	spin_lock(&sb_lock);
> -rescan:
> -	list_for_each_entry(sb, &super_blocks, s_list) {
> -		if (hlist_unhashed(&sb->s_instances))
> -			continue;
> -		if (sb->s_dev ==  dev) {
> -			sb->s_count++;
> -			spin_unlock(&sb_lock);
> -			down_read(&sb->s_umount);
> -			/* still alive? */
> -			if (sb->s_root && (sb->s_flags & MS_BORN))
> -				return sb;
> -			up_read(&sb->s_umount);
> -			/* nope, got unmounted */
> -			spin_lock(&sb_lock);
> -			__put_super(sb);
> -			goto rescan;
> -		}
> -	}
> -	spin_unlock(&sb_lock);
> -	return NULL;
> +	return __get_super(user_compare, &dev);
>  }
>  
>  /**
> -- 
> 1.8.4.2
> 
-- 
Jan Kara <jack at suse.com>
SUSE Labs, CR