[dm-devel] [RFC v2 PATCH 03/10] block: add block_device_operations methods to set and get reserved space

[Dave Chinner]

On Tue, Apr 12, 2016 at 12:42:46PM -0400, Brian Foster wrote:
> From: Mike Snitzer <snitzer at redhat.com>
> 
> [BF:
>  - Killed wrapper functions.
>  - Condensed to single bdev op.]
> 
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
>  include/linux/blkdev.h | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 669e419..6c6ea96 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1650,6 +1650,10 @@ struct blk_dax_ctl {
>  	pfn_t pfn;
>  };
>  
> +#define BDEV_RES_GET		0
> +#define BDEV_RES_MOD		(1 << 0)
> +#define BDEV_RES_PROVISION	(1 << 1)
> +
>  struct block_device_operations {
>  	int (*open) (struct block_device *, fmode_t);
>  	void (*release) (struct gendisk *, fmode_t);
> @@ -1667,6 +1671,8 @@ struct block_device_operations {
>  	int (*getgeo)(struct block_device *, struct hd_geometry *);
>  	/* this callback is with swap_lock and sometimes page table lock held */
>  	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
> +	int (*reserve_space) (struct block_device *, int, sector_t, sector_t,
> +			      sector_t *);
>  	struct module *owner;
>  	const struct pr_ops *pr_ops;

You know, I'm now wondering how much of this has overlap with the
iomap interface we are adding for the VFS IO paths to map and
allocate extents....

Cheers,

Dave.
-- 
Dave Chinner
david at fromorbit.com