linux-kernel - Re: [RFC 1/2] fs: configfs: add check

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Message-ID: <20120702084914.GB13247@dhcp-172-17-9-228.mtv.corp.google.com>
Date:	Mon, 2 Jul 2012 01:49:17 -0700
From:	Joel Becker <jlbec@...lplan.org>
To:	Andrzej Pietrasiewicz <andrzej.p@...sung.com>
Cc:	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Marek Szyprowski <m.szyprowski@...sung.com>
Subject: Re: [RFC 1/2] fs: configfs: add check_rmdir operation

NAK.  You should be using configfs_(un)depend_item() if you require the
item to stay alive.

Joel

On Thu, Jun 21, 2012 at 12:55:28PM +0200, Andrzej Pietrasiewicz wrote:
> The logic behind a subsystem which uses configfs might be that it is not
> desired to allow removing the pseudo directories (items or groups) in a
> mounted configfs while some criterion is not met, e.g. while some
> actions are in progress. This patch adds a check_rmdir operation to
> configfs_item_operations and to configfs_group_operations. The operation,
> if provided, is called before actual remove takes place and if the result
> is nonzero, the remove is not done and the error it returns is reported.
> 
> Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  fs/configfs/dir.c        |   20 ++++++++++++++++++++
>  include/linux/configfs.h |    2 ++
>  2 files changed, 22 insertions(+), 0 deletions(-)
> 
> diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
> index 7e6c52d..de2680f 100644
> --- a/fs/configfs/dir.c
> +++ b/fs/configfs/dir.c
> @@ -1408,12 +1408,32 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
>  		dead_item_owner = item->ci_type->ct_owner;
>  
>  	if (sd->s_type & CONFIGFS_USET_DIR) {
> +		if (item->ci_type && item->ci_type->ct_group_ops &&
> +		    item->ci_type->ct_group_ops->check_rmdir) {
> +		    	ret = item->ci_type->ct_group_ops->check_rmdir(
> +				to_config_group(parent_item), item);
> +			if (ret) {
> +				config_item_put(item);
> +				configfs_detach_rollback(dentry);
> +				return ret;
> +			}
> +		}
>  		configfs_detach_group(item);
>  
>  		mutex_lock(&subsys->su_mutex);
>  		client_disconnect_notify(parent_item, item);
>  		unlink_group(to_config_group(item));
>  	} else {
> +		if (item->ci_type && item->ci_type->ct_item_ops &&
> +		    item->ci_type->ct_item_ops->check_rmdir) {
> +		    	ret = item->ci_type->ct_item_ops->check_rmdir(
> +				to_config_group(parent_item), item);
> +			if (ret) {
> +				config_item_put(item);
> +				configfs_detach_rollback(dentry);
> +				return ret;
> +			}
> +		}
>  		configfs_detach_item(item);
>  
>  		mutex_lock(&subsys->su_mutex);
> diff --git a/include/linux/configfs.h b/include/linux/configfs.h
> index 34025df..f356a55 100644
> --- a/include/linux/configfs.h
> +++ b/include/linux/configfs.h
> @@ -225,6 +225,7 @@ struct configfs_item_operations {
>  	void (*release)(struct config_item *);
>  	ssize_t	(*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
>  	ssize_t	(*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
> +	int (*check_rmdir)(struct config_group *group, struct config_item *item);
>  	int (*allow_link)(struct config_item *src, struct config_item *target);
>  	int (*drop_link)(struct config_item *src, struct config_item *target);
>  };
> @@ -233,6 +234,7 @@ struct configfs_group_operations {
>  	struct config_item *(*make_item)(struct config_group *group, const char *name);
>  	struct config_group *(*make_group)(struct config_group *group, const char *name);
>  	int (*commit_item)(struct config_item *item);
> +	int (*check_rmdir)(struct config_group *group, struct config_item *item);
>  	void (*disconnect_notify)(struct config_group *group, struct config_item *item);
>  	void (*drop_item)(struct config_group *group, struct config_item *item);
>  };
> -- 
> 1.7.0.4
> 
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-- 

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			jlbec@...lplan.org
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