[mirror_ubuntu-bionic-kernel.git] / include / linux / fsnotify_backend.h

/*
 * Filesystem access notification for Linux
 *
 *  Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
 */

#ifndef __LINUX_FSNOTIFY_BACKEND_H
#define __LINUX_FSNOTIFY_BACKEND_H

#ifdef __KERNEL__

#include <linux/fs.h> /* struct inode */
#include <linux/list.h>
#include <linux/path.h> /* struct path */
#include <linux/spinlock.h>
#include <linux/types.h>

#include <asm/atomic.h>

/*
 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
 * convert between them.  dnotify only needs conversion at watch creation
 * so no perf loss there.  fanotify isn't defined yet, so it can use the
 * wholes if it needs more events.
 */
#define FS_ACCESS		0x00000001	/* File was accessed */
#define FS_MODIFY		0x00000002	/* File was modified */
#define FS_ATTRIB		0x00000004	/* Metadata changed */
#define FS_CLOSE_WRITE		0x00000008	/* Writtable file was closed */
#define FS_CLOSE_NOWRITE	0x00000010	/* Unwrittable file closed */
#define FS_OPEN			0x00000020	/* File was opened */
#define FS_MOVED_FROM		0x00000040	/* File was moved from X */
#define FS_MOVED_TO		0x00000080	/* File was moved to Y */
#define FS_CREATE		0x00000100	/* Subfile was created */
#define FS_DELETE		0x00000200	/* Subfile was deleted */
#define FS_DELETE_SELF		0x00000400	/* Self was deleted */
#define FS_MOVE_SELF		0x00000800	/* Self was moved */

#define FS_UNMOUNT		0x00002000	/* inode on umount fs */
#define FS_Q_OVERFLOW		0x00004000	/* Event queued overflowed */
#define FS_IN_IGNORED		0x00008000	/* last inotify event here */

#define FS_IN_ISDIR		0x40000000	/* event occurred against dir */
#define FS_IN_ONESHOT		0x80000000	/* only send event once */

#define FS_DN_RENAME		0x10000000	/* file renamed */
#define FS_DN_MULTISHOT		0x20000000	/* dnotify multishot */

struct fsnotify_group;
struct fsnotify_event;

/*
 * Each group much define these ops.  The fsnotify infrastructure will call
 * these operations for each relevant group.
 *
 * handle_event - main call for a group to handle an fs event
 * free_group_priv - called when a group refcnt hits 0 to clean up the private union
 */
struct fsnotify_ops {
	int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
	void (*free_group_priv)(struct fsnotify_group *group);
};

/*
 * A group is a "thing" that wants to receive notification about filesystem
 * events.  The mask holds the subset of event types this group cares about.
 * refcnt on a group is up to the implementor and at any moment if it goes 0
 * everything will be cleaned up.
 */
struct fsnotify_group {
	/*
	 * global list of all groups receiving events from fsnotify.
	 * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex
	 * or fsnotify_grp_srcu depending on write vs read.
	 */
	struct list_head group_list;

	/*
	 * Defines all of the event types in which this group is interested.
	 * This mask is a bitwise OR of the FS_* events from above.  Each time
	 * this mask changes for a group (if it changes) the correct functions
	 * must be called to update the global structures which indicate global
	 * interest in event types.
	 */
	__u32 mask;

	/*
	 * How the refcnt is used is up to each group.  When the refcnt hits 0
	 * fsnotify will clean up all of the resources associated with this group.
	 * As an example, the dnotify group will always have a refcnt=1 and that
	 * will never change.  Inotify, on the other hand, has a group per
	 * inotify_init() and the refcnt will hit 0 only when that fd has been
	 * closed.
	 */
	atomic_t refcnt;		/* things with interest in this group */
	unsigned int group_num;		/* simply prevents accidental group collision */

	const struct fsnotify_ops *ops;	/* how this group handles things */

	/* prevents double list_del of group_list.  protected by global fsnotify_gr_mutex */
	bool on_group_list;

	/* groups can define private fields here or use the void *private */
	union {
		void *private;
	};
};

/*
 * all of the information about the original object we want to now send to
 * a group.  If you want to carry more info from the accessing task to the
 * listener this structure is where you need to be adding fields.
 */
struct fsnotify_event {
	spinlock_t lock;	/* protection for the associated event_holder and private_list */
	/* to_tell may ONLY be dereferenced during handle_event(). */
	struct inode *to_tell;	/* either the inode the event happened to or its parent */
	/*
	 * depending on the event type we should have either a path or inode
	 * We hold a reference on path, but NOT on inode.  Since we have the ref on
	 * the path, it may be dereferenced at any point during this object's
	 * lifetime.  That reference is dropped when this object's refcnt hits
	 * 0.  If this event contains an inode instead of a path, the inode may
	 * ONLY be used during handle_event().
	 */
	union {
		struct path path;
		struct inode *inode;
	};
/* when calling fsnotify tell it if the data is a path or inode */
#define FSNOTIFY_EVENT_NONE	0
#define FSNOTIFY_EVENT_PATH	1
#define FSNOTIFY_EVENT_INODE	2
#define FSNOTIFY_EVENT_FILE	3
	int data_type;		/* which of the above union we have */
	atomic_t refcnt;	/* how many groups still are using/need to send this event */
	__u32 mask;		/* the type of access, bitwise OR for FS_* event types */
};

#ifdef CONFIG_FSNOTIFY

/* called from the vfs helpers */

/* main fsnotify call to send events */
extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is);


/* called from fsnotify listeners, such as fanotify or dnotify */

/* must call when a group changes its ->mask */
extern void fsnotify_recalc_global_mask(void);
/* get a reference to an existing or create a new group */
extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num,
						    __u32 mask,
						    const struct fsnotify_ops *ops);
/* drop reference on a group from fsnotify_obtain_group */
extern void fsnotify_put_group(struct fsnotify_group *group);

/* take a reference to an event */
extern void fsnotify_get_event(struct fsnotify_event *event);
extern void fsnotify_put_event(struct fsnotify_event *event);
/* find private data previously attached to an event */
extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group,
									struct fsnotify_event *event);

/* put here because inotify does some weird stuff when destroying watches */
extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
						    void *data, int data_is);
#else

static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
{}
#endif	/* CONFIG_FSNOTIFY */

#endif	/* __KERNEL __ */

#endif	/* __LINUX_FSNOTIFY_BACKEND_H */
Commit	Line	Data
90586523 EP	1	/*
	2	* Filesystem access notification for Linux
	3	*
	4	* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
	5	*/
	6
	7	#ifndef __LINUX_FSNOTIFY_BACKEND_H
	8	#define __LINUX_FSNOTIFY_BACKEND_H
	9
	10	#ifdef __KERNEL__
	11
	12	#include <linux/fs.h> /* struct inode */
	13	#include <linux/list.h>
	14	#include <linux/path.h> /* struct path */
	15	#include <linux/spinlock.h>
	16	#include <linux/types.h>
	17
	18	#include <asm/atomic.h>
	19
	20	/*
	21	* IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
	22	* convert between them. dnotify only needs conversion at watch creation
	23	* so no perf loss there. fanotify isn't defined yet, so it can use the
	24	* wholes if it needs more events.
	25	*/
	26	#define FS_ACCESS 0x00000001 /* File was accessed */
	27	#define FS_MODIFY 0x00000002 /* File was modified */
	28	#define FS_ATTRIB 0x00000004 /* Metadata changed */
	29	#define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
	30	#define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
	31	#define FS_OPEN 0x00000020 /* File was opened */
	32	#define FS_MOVED_FROM 0x00000040 /* File was moved from X */
	33	#define FS_MOVED_TO 0x00000080 /* File was moved to Y */
	34	#define FS_CREATE 0x00000100 /* Subfile was created */
	35	#define FS_DELETE 0x00000200 /* Subfile was deleted */
	36	#define FS_DELETE_SELF 0x00000400 /* Self was deleted */
	37	#define FS_MOVE_SELF 0x00000800 /* Self was moved */
	38
	39	#define FS_UNMOUNT 0x00002000 /* inode on umount fs */
	40	#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
	41	#define FS_IN_IGNORED 0x00008000 /* last inotify event here */
	42
	43	#define FS_IN_ISDIR 0x40000000 /* event occurred against dir */
	44	#define FS_IN_ONESHOT 0x80000000 /* only send event once */
	45
	46	#define FS_DN_RENAME 0x10000000 /* file renamed */
	47	#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
	48
	49	struct fsnotify_group;
	50	struct fsnotify_event;
	51
	52	/*
	53	* Each group much define these ops. The fsnotify infrastructure will call
	54	* these operations for each relevant group.
	55	*
	56	* handle_event - main call for a group to handle an fs event
	57	* free_group_priv - called when a group refcnt hits 0 to clean up the private union
	58	*/
	59	struct fsnotify_ops {
	60	int (handle_event)(struct fsnotify_group group, struct fsnotify_event *event);
	61	void (free_group_priv)(struct fsnotify_group group);
	62	};
	63
	64	/*
65	* A group is a "thing" that wants to receive notification about filesystem
66	* events. The mask holds the subset of event types this group cares about.
67	* refcnt on a group is up to the implementor and at any moment if it goes 0
68	* everything will be cleaned up.
69	*/
70	struct fsnotify_group {
71	/*
72	* global list of all groups receiving events from fsnotify.
73	* anchored by fsnotify_groups and protected by either fsnotify_grp_mutex
74	* or fsnotify_grp_srcu depending on write vs read.
75	*/
76	struct list_head group_list;
77
78	/*
79	* Defines all of the event types in which this group is interested.
80	* This mask is a bitwise OR of the FS_* events from above. Each time
81	* this mask changes for a group (if it changes) the correct functions
82	* must be called to update the global structures which indicate global
83	* interest in event types.
84	*/
85	__u32 mask;
86
87	/*
88	* How the refcnt is used is up to each group. When the refcnt hits 0
89	* fsnotify will clean up all of the resources associated with this group.
90	* As an example, the dnotify group will always have a refcnt=1 and that
91	* will never change. Inotify, on the other hand, has a group per
92	* inotify_init() and the refcnt will hit 0 only when that fd has been
93	* closed.
94	*/
95	atomic_t refcnt; /* things with interest in this group */
96	unsigned int group_num; /* simply prevents accidental group collision */
97
98	const struct fsnotify_ops ops; / how this group handles things */
99
100	/* prevents double list_del of group_list. protected by global fsnotify_gr_mutex */
101	bool on_group_list;
102
103	/* groups can define private fields here or use the void private /
104	union {
105	void *private;
106	};
107	};
108
109	/*
110	* all of the information about the original object we want to now send to
111	* a group. If you want to carry more info from the accessing task to the
112	* listener this structure is where you need to be adding fields.
113	*/
114	struct fsnotify_event {
115	spinlock_t lock; /* protection for the associated event_holder and private_list */
116	/* to_tell may ONLY be dereferenced during handle_event(). */
117	struct inode to_tell; / either the inode the event happened to or its parent */
118	/*
119	* depending on the event type we should have either a path or inode
120	* We hold a reference on path, but NOT on inode. Since we have the ref on
121	* the path, it may be dereferenced at any point during this object's
122	* lifetime. That reference is dropped when this object's refcnt hits
123	* 0. If this event contains an inode instead of a path, the inode may
124	* ONLY be used during handle_event().
125	*/
126	union {
127	struct path path;
128	struct inode *inode;
129	};
130	/* when calling fsnotify tell it if the data is a path or inode */
131	#define FSNOTIFY_EVENT_NONE 0
132	#define FSNOTIFY_EVENT_PATH 1
133	#define FSNOTIFY_EVENT_INODE 2
134	#define FSNOTIFY_EVENT_FILE 3
135	int data_type; /* which of the above union we have */
136	atomic_t refcnt; /* how many groups still are using/need to send this event */
137	__u32 mask; /* the type of access, bitwise OR for FS_* event types */
138	};
139
140	#ifdef CONFIG_FSNOTIFY
141
142	/* called from the vfs helpers */
143
144	/* main fsnotify call to send events */
145	extern void fsnotify(struct inode to_tell, __u32 mask, void data, int data_is);
146
147
148	/* called from fsnotify listeners, such as fanotify or dnotify */
149
150	/* must call when a group changes its ->mask */
151	extern void fsnotify_recalc_global_mask(void);
152	/* get a reference to an existing or create a new group */
153	extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num,
154	__u32 mask,
155	const struct fsnotify_ops *ops);
156	/* drop reference on a group from fsnotify_obtain_group */
157	extern void fsnotify_put_group(struct fsnotify_group *group);
158
159	/* take a reference to an event */
160	extern void fsnotify_get_event(struct fsnotify_event *event);
161	extern void fsnotify_put_event(struct fsnotify_event *event);
162	/* find private data previously attached to an event */
163	extern struct fsnotify_event_private_data fsnotify_get_priv_from_event(struct fsnotify_group group,
164	struct fsnotify_event *event);
165
166	/* put here because inotify does some weird stuff when destroying watches */
167	extern struct fsnotify_event fsnotify_create_event(struct inode to_tell, __u32 mask,
168	void *data, int data_is);
169	#else
170
171	static inline void fsnotify(struct inode to_tell, __u32 mask, void data, int data_is)
172	{}
173	#endif /* CONFIG_FSNOTIFY */
174
175	#endif /* __KERNEL __ */
176
177	#endif /* __LINUX_FSNOTIFY_BACKEND_H */