[PATCH 41/44] block: switch disk_part_iter_* to use a struct block_device

[Jan Kara]

On Thu 26-11-20 14:04:19, Christoph Hellwig wrote:
> Switch the partition iter infrastructure to iterate over block_device
> references instead of hd_struct ones mostly used to get at the
> block_device.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>

The patch mostly looks good. Two comments below.

> diff --git a/block/genhd.c b/block/genhd.c
> index 28299b24173be1..b58595f2ca33b1 100644
> --- a/block/genhd.c
> +++ b/block/genhd.c
> @@ -233,7 +233,7 @@ EXPORT_SYMBOL_GPL(disk_part_iter_init);
>   * CONTEXT:
>   * Don't care.
>   */
> -struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
> +struct block_device *disk_part_iter_next(struct disk_part_iter *piter)
>  {
>  	struct disk_part_tbl *ptbl;
>  	int inc, end;

There's:

        /* put the last partition */
        disk_put_part(piter->part);
        piter->part = NULL;

at the beginning of disk_part_iter_next() which also needs switching to
bdput(), doesn't it?

> @@ -271,8 +271,7 @@ struct hd_struct *disk_part_iter_next(struct disk_part_iter *piter)
>  		      piter->idx == 0))
>  			continue;
>  
> -		get_device(part_to_dev(part->bd_part));
> -		piter->part = part->bd_part;
> +		piter->part = bdgrab(part);

bdgrab() could return NULL if we are racing with delete_partition() so I
think we need to take care of that.

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