Re: [dm-devel] [PATCH 3/5] block: simplify holder symlink handling

[Mike Snitzer <snitzer redhat com>]

On Mon, Nov 01 2010 at 12:15pm -0400,
Tejun Heo <tj kernel org> wrote:

> Code to manage symlinks in /sys/block/*/{holders|slaves} are overly
> complex with multiple holder considerations, redundant extra
> references to all involved kobjects, unused generic kobject holder
> support and unnecessary mixup with bd_claim/release functionalities.
> 
> Strip it down to what's necessary (single gendisk holder) and make it
> use a separate interface.  This is a step for cleaning up
> bd_claim/release.  This patch makes dm-table slightly more complex but
> it will be simplified again with further changes.
> 
> Signed-off-by: Tejun Heo <tj kernel org>
> Cc: Neil Brown <neilb suse de>
> Cc: dm-devel redhat com

Acked-by: Mike Snitzer <snitzer redhat com>

> ---
>  drivers/md/dm-table.c |   23 +++-
>  drivers/md/md.c       |    4 +-
>  fs/block_dev.c        |  322 +++++++------------------------------------------
>  include/linux/fs.h    |   16 ++-
>  4 files changed, 74 insertions(+), 291 deletions(-)
> 
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 90267f8..2c876ff 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -328,12 +328,22 @@ static int open_dev(struct dm_dev_internal *d, dev_t dev,
>  	bdev = open_by_devnum(dev, d->dm_dev.mode);
>  	if (IS_ERR(bdev))
>  		return PTR_ERR(bdev);
> -	r = bd_claim_by_disk(bdev, _claim_ptr, dm_disk(md));
> -	if (r)
> +
> +	r = bd_claim(bdev, _claim_ptr);
> +	if (r) {
>  		blkdev_put(bdev, d->dm_dev.mode);
> -	else
> -		d->dm_dev.bdev = bdev;
> -	return r;
> +		return r;
> +	}
> +
> +	r = bd_link_disk_holder(bdev, dm_disk(md));
> +	if (r) {
> +		bd_release(bdev);
> +		blkdev_put(bdev, d->dm_dev.mode);
> +		return r;
> +	}
> +
> +	d->dm_dev.bdev = bdev;
> +	return 0;
>  }
>  
>  /*
> @@ -344,7 +354,8 @@ static void close_dev(struct dm_dev_internal *d, struct mapped_device *md)
>  	if (!d->dm_dev.bdev)
>  		return;
>  
> -	bd_release_from_disk(d->dm_dev.bdev, dm_disk(md));
> +	bd_unlink_disk_holder(d->dm_dev.bdev);
> +	bd_release(d->dm_dev.bdev);
>  	blkdev_put(d->dm_dev.bdev, d->dm_dev.mode);
>  	d->dm_dev.bdev = NULL;
>  }