[RFC PATCH 1/9] block: add block_device_operations methods to set and get reserved space

[Carlos Maiolino]

Hi,

Good news about this interface, I just have a small suggestion in this patch:

On Thu, Mar 17, 2016 at 10:30:29AM -0400, Brian Foster wrote:
> From: Mike Snitzer <snitzer at redhat.com>
> 
> Signed-off-by: Mike Snitzer <snitzer at redhat.com>
> ---
>  fs/block_dev.c         | 20 ++++++++++++++++++++
>  include/linux/blkdev.h |  5 +++++
>  2 files changed, 25 insertions(+)
> 
> diff --git a/fs/block_dev.c b/fs/block_dev.c
> index 826b164..375a2e4 100644
> --- a/fs/block_dev.c
> +++ b/fs/block_dev.c
> @@ -497,6 +497,26 @@ long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
>  }
>  EXPORT_SYMBOL_GPL(bdev_direct_access);
>  
> +int blk_reserve_space(struct block_device *bdev, sector_t nr_sects)
> +{
> +	const struct block_device_operations *ops = bdev->bd_disk->fops;
> +
> +	if (!ops->reserve_space)
> +		return -EOPNOTSUPP;
> +	return ops->reserve_space(bdev, nr_sects);
> +}
> +EXPORT_SYMBOL_GPL(blk_reserve_space);

Wouldn't be better to have this function name standardized accordingly to the
next one? Something like blk_set_reserved_space() maybe?

> +
> +int blk_get_reserved_space(struct block_device *bdev, sector_t *nr_sects)
> +{
> +	const struct block_device_operations *ops = bdev->bd_disk->fops;
> +
> +	if (!ops->get_reserved_space)
> +		return -EOPNOTSUPP;
> +	return ops->get_reserved_space(bdev, nr_sects);
> +}
> +EXPORT_SYMBOL_GPL(blk_get_reserved_space);
> +
>  /*
>   * pseudo-fs
>   */
> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> index 413c84f..f212fe5 100644
> --- a/include/linux/blkdev.h
> +++ b/include/linux/blkdev.h
> @@ -1664,6 +1664,8 @@ 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 *, sector_t);
> +	int (*get_reserved_space) (struct block_device *, sector_t *);
>  	struct module *owner;
>  	const struct pr_ops *pr_ops;
>  };
> @@ -1674,6 +1676,9 @@ extern int bdev_read_page(struct block_device *, sector_t, struct page *);
>  extern int bdev_write_page(struct block_device *, sector_t, struct page *,
>  						struct writeback_control *);
>  extern long bdev_direct_access(struct block_device *, struct blk_dax_ctl *);
> +
> +extern int blk_reserve_space(struct block_device *, sector_t);
> +extern int blk_get_reserved_space(struct block_device *, sector_t *);
>  #else /* CONFIG_BLOCK */
>  
>  struct block_device;
> -- 
> 2.4.3
> 
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-- 
Carlos