splinter work on generic fs notification framework

[Greg KH]

On Tue, Jul 12, 2005 at 02:18:20PM -0500, Timothy R. Chavez wrote:
> Hi,
> 
> I've CCed some folks that I thought might be interested in this update and may
> not be on linux-audit.

Unfortunatly linux-audit is a closed list, so this post will probably
bounce :(

> Based on recent discussion on LKML and some IRC conversations, a generic file 
> system notification framework is being written to merge common functionality 
> between the "auditfs" component of the audit framework and Inotify.  This 
> framework will be mostly comprised of the watch logic implemented by the 
> "auditfs" component (I_AUDIT, hash table, update hook, helper functions, etc) 
> and the fsnotify hooks written by Robert Love.  User's of this framework will 
> pass their own callback functions in when adding a watch via this framework 
> which will effectively be stored on the watch and called from the watch hook 
> that discovers it.
> 
> We introduce fs/watch.c and include/linux/watch.h

fswatch.h perhaps?

> diff --exclude=.git -Nurp audit-2.6/include/linux/watch.h audit-2.6.git-fsnotify/include/linux/watch.h
> --- audit-2.6/include/linux/watch.h	1969-12-31 18:00:00.000000000 -0600
> +++ audit-2.6.git-fsnotify/include/linux/watch.h	2005-07-11 01:33:45.000000000 -0500
> @@ -0,0 +1,57 @@
> +#ifndef _WATCH_H
> +#define _WATCH_H
> +
> +struct watch {
> +	atomic_t                w_count;

Use a struct kref instead of rolling your own here.

> +	struct hlist_node	w_node;		/* per-directory list         */
> +	struct hlist_node	w_master;	/* Master watch list          */
> +	struct hlist_node	w_watched;	/* Watches on inode           */
> +	dev_t			w_dev;		/* Superblock device          */
> +	__u32			w_perms;	/* Permissions filtering      */
> +	char			*w_name;	/* Watch beneath parent       */
> +	char			*w_path;	/* Insertion path             */
> +	char			*w_filterkey;	/* An arbitrary filtering key */
> +	void			(*w_func);	/* Callback function          */
> +};
> +
> +struct watch_inode_data {
> +        int			count;

same here.

> +        struct watch_inode_data *next_hash;	/* Watch data hash table      */

formatting issue.

> +	struct inode		*inode;		/* Inode to which it belongs  */
> +	struct hlist_head	watches;	/* List of watches on inode   */
> +	struct hlist_head	watchlist;	/* Watches for children       */
> +};
> +
> +/* User */
> +extern int watch_add(struct watch *, struct inode *);
> +extern int watch_rem(struct watch *, struct inode *);
> +extern struct watch *watch_alloc(void);
> +extern struct watch *watch_get(struct watch *);
> +extern void watch_free(struct watch *);
> +extern void watch_put(struct watch *);

Why a difference?  The last watch_put should free the structure, right?

> +
> +/* Internals */
> +
> +extern int watch_init(void);
> +extern void watch_inode_free(struct inode *);
> +extern void watch_update(struct dentry *, int);
> +
> +/* Hooks */
> +#ifdef CONFIG_FSWATCH
> +extern const char *watch_notify_oldname_init(const char *);
> +extern void watch_notify_oldname_free(const char *);
> +extern void watch_notify_move(struct inode *, struct inode *, const char *, const char *, int);
> +extern void watch_notify_unlink(struct dentry *, struct inode *);
> +extern void watch_notify_rmdir(struct dentry *, struct inode *, struct inode *);
> +extern void watch_notify_create(struct inode *, const char *);
> +extern void watch_notify_mkdir(struct inode *, const char *);
> +extern void watch_notify_access(struct dentry *dentry);
> +extern void watch_notify_modify(struct dentry *dentry);
> +extern void watch_notify_open(struct dentry *dentry, int mask);
> +extern void watch_notify_close(struct file *file);
> +extern void watch_notify_xattr(struct dentry *dentry);
> +extern void watch_notify_change(struct dentry *dentry, unsigned int ia_valid);
> +#endif /* CONFIG_FSWATCH */

No static inlines if !CONFIG_FSWATCH?

thanks,

greg k-h