[net-next-2.6.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;
struct fsnotify_mark_entry;

/*
 * Each group much define these ops.  The fsnotify infrastructure will call
 * these operations for each relevant group.
 *
 * should_send_event - given a group, inode, and mask this function determines
 *		if the group is interested in this event.
 * 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
 * freeing-mark - this means that a mark has been flagged to die when everything
 *		finishes using it.  The function is supplied with what must be a
 *		valid group and inode to use to clean up.
 */
struct fsnotify_ops {
	bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, __u32 mask);
	int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
	void (*free_group_priv)(struct fsnotify_group *group);
	void (*freeing_mark)(struct fsnotify_mark_entry *entry, 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 */

	/* stores all fastapth entries assoc with this group so they can be cleaned on unregister */
	spinlock_t mark_lock;		/* protect mark_entries list */
	atomic_t num_marks;		/* 1 for each mark entry and 1 for not being
					 * past the point of no return when freeing
					 * a group */
	struct list_head mark_entries;	/* all inode mark entries for this group */

	/* prevents double list_del of group_list.  protected by global fsnotify_grp_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 */
};

/*
 * a mark is simply an entry attached to an in core inode which allows an
 * fsnotify listener to indicate they are either no longer interested in events
 * of a type matching mask or only interested in those events.
 *
 * these are flushed when an inode is evicted from core and may be flushed
 * when the inode is modified (as seen by fsnotify_access).  Some fsnotify users
 * (such as dnotify) will flush these when the open fd is closed and not at
 * inode eviction or modification.
 */
struct fsnotify_mark_entry {
	__u32 mask;			/* mask this mark entry is for */
	/* we hold ref for each i_list and g_list.  also one ref for each 'thing'
	 * in kernel that found and may be using this mark. */
	atomic_t refcnt;		/* active things looking at this mark */
	struct inode *inode;		/* inode this entry is associated with */
	struct fsnotify_group *group;	/* group this mark entry is for */
	struct hlist_node i_list;	/* list of mark_entries by inode->i_fsnotify_mark_entries */
	struct list_head g_list;	/* list of mark_entries by group->i_fsnotify_mark_entries */
	spinlock_t lock;		/* protect group, inode, and killme */
	struct list_head free_i_list;	/* tmp list used when freeing this mark */
	struct list_head free_g_list;	/* tmp list used when freeing this mark */
	void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */
};

#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);
extern void __fsnotify_inode_delete(struct inode *inode);


/* 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);
/* run all marks associated with this group and update group->mask */
extern void fsnotify_recalc_group_mask(struct fsnotify_group *group);
/* 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);

/* functions used to manipulate the marks attached to inodes */

/* run all marks associated with an inode and update inode->i_fsnotify_mask */
extern void fsnotify_recalc_inode_mask(struct inode *inode);
extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry));
/* find (and take a reference) to a mark associated with group and inode */
extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode);
/* attach the mark to both the group and the inode */
extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode);
/* given a mark, flag it to be freed when all references are dropped */
extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry);
/* run all the marks in a group, and flag them to be freed */
extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry);
extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry);

/* 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)
{}

static inline void __fsnotify_inode_delete(struct inode *inode)
{}

#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;
3be25f49	51	struct fsnotify_mark_entry;
90586523 EP	52
	53	/*
	54	* Each group much define these ops. The fsnotify infrastructure will call
	55	* these operations for each relevant group.
	56	*
3be25f49 EP	57	* should_send_event - given a group, inode, and mask this function determines
3be25f49 EP	58	* if the group is interested in this event.
90586523 EP	59	* handle_event - main call for a group to handle an fs event
90586523 EP	60	* free_group_priv - called when a group refcnt hits 0 to clean up the private union
3be25f49 EP	61	* freeing-mark - this means that a mark has been flagged to die when everything
	62	* finishes using it. The function is supplied with what must be a
	63	* valid group and inode to use to clean up.
90586523 EP	64	*/
90586523 EP	65	struct fsnotify_ops {
3be25f49	66	bool (should_send_event)(struct fsnotify_group group, struct inode *inode, __u32 mask);
90586523 EP	67	int (handle_event)(struct fsnotify_group group, struct fsnotify_event *event);
90586523 EP	68	void (free_group_priv)(struct fsnotify_group group);
3be25f49	69	void (freeing_mark)(struct fsnotify_mark_entry entry, struct fsnotify_group *group);
90586523 EP	70	};
	71
	72	/*
	73	* A group is a "thing" that wants to receive notification about filesystem
	74	* events. The mask holds the subset of event types this group cares about.
	75	* refcnt on a group is up to the implementor and at any moment if it goes 0
	76	* everything will be cleaned up.
	77	*/
	78	struct fsnotify_group {
	79	/*
	80	* global list of all groups receiving events from fsnotify.
	81	* anchored by fsnotify_groups and protected by either fsnotify_grp_mutex
	82	* or fsnotify_grp_srcu depending on write vs read.
	83	*/
	84	struct list_head group_list;
	85
	86	/*
	87	* Defines all of the event types in which this group is interested.
	88	* This mask is a bitwise OR of the FS_* events from above. Each time
	89	* this mask changes for a group (if it changes) the correct functions
	90	* must be called to update the global structures which indicate global
	91	* interest in event types.
	92	*/
	93	__u32 mask;
	94
	95	/*
	96	* How the refcnt is used is up to each group. When the refcnt hits 0
	97	* fsnotify will clean up all of the resources associated with this group.
	98	* As an example, the dnotify group will always have a refcnt=1 and that
	99	* will never change. Inotify, on the other hand, has a group per
	100	* inotify_init() and the refcnt will hit 0 only when that fd has been
	101	* closed.
	102	*/
	103	atomic_t refcnt; /* things with interest in this group */
	104	unsigned int group_num; /* simply prevents accidental group collision */
	105
	106	const struct fsnotify_ops ops; / how this group handles things */
	107
3be25f49 EP	108	/* stores all fastapth entries assoc with this group so they can be cleaned on unregister */
	109	spinlock_t mark_lock; /* protect mark_entries list */
	110	atomic_t num_marks; /* 1 for each mark entry and 1 for not being
	111	* past the point of no return when freeing
	112	* a group */
	113	struct list_head mark_entries; /* all inode mark entries for this group */
	114
	115	/* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */
90586523 EP	116	bool on_group_list;
	117
	118	/* groups can define private fields here or use the void private /
	119	union {
	120	void *private;
	121	};
	122	};
	123
	124	/*
	125	* all of the information about the original object we want to now send to
	126	* a group. If you want to carry more info from the accessing task to the
	127	* listener this structure is where you need to be adding fields.
	128	*/
	129	struct fsnotify_event {
	130	spinlock_t lock; /* protection for the associated event_holder and private_list */
	131	/* to_tell may ONLY be dereferenced during handle_event(). */
	132	struct inode to_tell; / either the inode the event happened to or its parent */
	133	/*
	134	* depending on the event type we should have either a path or inode
	135	* We hold a reference on path, but NOT on inode. Since we have the ref on
	136	* the path, it may be dereferenced at any point during this object's
	137	* lifetime. That reference is dropped when this object's refcnt hits
	138	* 0. If this event contains an inode instead of a path, the inode may
	139	* ONLY be used during handle_event().
	140	*/
	141	union {
	142	struct path path;
	143	struct inode *inode;
	144	};
	145	/* when calling fsnotify tell it if the data is a path or inode */
	146	#define FSNOTIFY_EVENT_NONE 0
	147	#define FSNOTIFY_EVENT_PATH 1
	148	#define FSNOTIFY_EVENT_INODE 2
	149	#define FSNOTIFY_EVENT_FILE 3
	150	int data_type; /* which of the above union we have */
	151	atomic_t refcnt; /* how many groups still are using/need to send this event */
	152	__u32 mask; /* the type of access, bitwise OR for FS_* event types */
	153	};
	154
3be25f49 EP	155	/*
	156	* a mark is simply an entry attached to an in core inode which allows an
	157	* fsnotify listener to indicate they are either no longer interested in events
	158	* of a type matching mask or only interested in those events.
	159	*
	160	* these are flushed when an inode is evicted from core and may be flushed
	161	* when the inode is modified (as seen by fsnotify_access). Some fsnotify users
	162	* (such as dnotify) will flush these when the open fd is closed and not at
	163	* inode eviction or modification.
	164	*/
	165	struct fsnotify_mark_entry {
	166	__u32 mask; /* mask this mark entry is for */
	167	/* we hold ref for each i_list and g_list. also one ref for each 'thing'
	168	* in kernel that found and may be using this mark. */
	169	atomic_t refcnt; /* active things looking at this mark */
	170	struct inode inode; / inode this entry is associated with */
	171	struct fsnotify_group group; / group this mark entry is for */
	172	struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */
	173	struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */
	174	spinlock_t lock; /* protect group, inode, and killme */
	175	struct list_head free_i_list; /* tmp list used when freeing this mark */
	176	struct list_head free_g_list; /* tmp list used when freeing this mark */
	177	void (free_mark)(struct fsnotify_mark_entry entry); /* called on final put+free */
	178	};
	179
90586523 EP	180	#ifdef CONFIG_FSNOTIFY
	181
	182	/* called from the vfs helpers */
	183
	184	/* main fsnotify call to send events */
	185	extern void fsnotify(struct inode to_tell, __u32 mask, void data, int data_is);
3be25f49	186	extern void __fsnotify_inode_delete(struct inode *inode);
90586523 EP	187
	188
	189	/* called from fsnotify listeners, such as fanotify or dnotify */
	190
	191	/* must call when a group changes its ->mask */
	192	extern void fsnotify_recalc_global_mask(void);
	193	/* get a reference to an existing or create a new group */
	194	extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num,
	195	__u32 mask,
	196	const struct fsnotify_ops *ops);
3be25f49 EP	197	/* run all marks associated with this group and update group->mask */
3be25f49 EP	198	extern void fsnotify_recalc_group_mask(struct fsnotify_group *group);
90586523 EP	199	/* drop reference on a group from fsnotify_obtain_group */
	200	extern void fsnotify_put_group(struct fsnotify_group *group);
	201
	202	/* take a reference to an event */
	203	extern void fsnotify_get_event(struct fsnotify_event *event);
	204	extern void fsnotify_put_event(struct fsnotify_event *event);
	205	/* find private data previously attached to an event */
	206	extern struct fsnotify_event_private_data fsnotify_get_priv_from_event(struct fsnotify_group group,
	207	struct fsnotify_event *event);
	208
3be25f49 EP	209	/* functions used to manipulate the marks attached to inodes */
	210
	211	/* run all marks associated with an inode and update inode->i_fsnotify_mask */
	212	extern void fsnotify_recalc_inode_mask(struct inode *inode);
	213	extern void fsnotify_init_mark(struct fsnotify_mark_entry entry, void (free_mark)(struct fsnotify_mark_entry *entry));
	214	/* find (and take a reference) to a mark associated with group and inode */
	215	extern struct fsnotify_mark_entry fsnotify_find_mark_entry(struct fsnotify_group group, struct inode *inode);
	216	/* attach the mark to both the group and the inode */
	217	extern int fsnotify_add_mark(struct fsnotify_mark_entry entry, struct fsnotify_group group, struct inode *inode);
	218	/* given a mark, flag it to be freed when all references are dropped */
	219	extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry);
	220	/* run all the marks in a group, and flag them to be freed */
	221	extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
	222	extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry);
	223	extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry);
	224
90586523 EP	225	/* put here because inotify does some weird stuff when destroying watches */
	226	extern struct fsnotify_event fsnotify_create_event(struct inode to_tell, __u32 mask,
	227	void *data, int data_is);
	228	#else
	229
	230	static inline void fsnotify(struct inode to_tell, __u32 mask, void data, int data_is)
	231	{}
3be25f49 EP	232
	233	static inline void __fsnotify_inode_delete(struct inode *inode)
	234	{}
	235
90586523 EP	236	#endif /* CONFIG_FSNOTIFY */
	237
	238	#endif /* __KERNEL __ */
	239
	240	#endif /* __LINUX_FSNOTIFY_BACKEND_H */