[deliverable/linux.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/idr.h> /* inotify uses this */
#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 <linux/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_OPEN_PERM		0x00010000	/* open event in an permission hook */
#define FS_ACCESS_PERM		0x00020000	/* access event in a permissions hook */

#define FS_EXCL_UNLINK		0x04000000	/* do not send events if object is unlinked */
#define FS_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 */

/* This inode cares about things that happen to its children.  Always set for
 * dnotify and inotify. */
#define FS_EVENT_ON_CHILD	0x08000000

/* This is a list of all events that may get sent to a parernt based on fs event
 * happening to inodes inside that directory */
#define FS_EVENTS_POSS_ON_CHILD   (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
				   FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
				   FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
				   FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)

#define FS_MOVE			(FS_MOVED_FROM | FS_MOVED_TO)

#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)

#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
			     FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
			     FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
			     FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
			     FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
			     FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)

struct fsnotify_group;
struct fsnotify_event;
struct fsnotify_mark;
struct fsnotify_event_private_data;
struct fsnotify_fname;

/*
 * 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
 * freeing_mark - called when a mark is being destroyed for some reason.  The group
 * 		MUST be holding a reference on each mark and that reference must be
 * 		dropped in this function.  inotify uses this function to send
 * 		userspace messages that marks have been removed.
 */
struct fsnotify_ops {
	int (*handle_event)(struct fsnotify_group *group,
			    struct inode *inode,
			    struct fsnotify_mark *inode_mark,
			    struct fsnotify_mark *vfsmount_mark,
			    u32 mask, void *data, int data_type,
			    const unsigned char *file_name, u32 cookie);
	void (*free_group_priv)(struct fsnotify_group *group);
	void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
	void (*free_event)(struct fsnotify_event *event);
};

/*
 * 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 {
	struct list_head list;
	/* inode may ONLY be dereferenced during handle_event(). */
	struct inode *inode;	/* either the inode the event happened to or its parent */
	u32 mask;		/* the type of access, bitwise OR for FS_* event types */
};

/*
 * 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 {
	/*
	 * 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 */

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

	/* needed to send notification to userspace */
	struct mutex notification_mutex;	/* protect the notification_list */
	struct list_head notification_list;	/* list of event_holder this group needs to send to userspace */
	wait_queue_head_t notification_waitq;	/* read() on the notification file blocks on this waitq */
	unsigned int q_len;			/* events on the queue */
	unsigned int max_events;		/* maximum events allowed on the list */
	/*
	 * Valid fsnotify group priorities.  Events are send in order from highest
	 * priority to lowest priority.  We default to the lowest priority.
	 */
	#define FS_PRIO_0	0 /* normal notifiers, no permissions */
	#define FS_PRIO_1	1 /* fanotify content based access control */
	#define FS_PRIO_2	2 /* fanotify pre-content access */
	unsigned int priority;
	bool shutdown;		/* group is being shut down, don't queue more events */

	/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
	struct mutex mark_mutex;	/* protect marks_list */
	atomic_t num_marks;		/* 1 for each mark and 1 for not being
					 * past the point of no return when freeing
					 * a group */
	struct list_head marks_list;	/* all inode marks for this group */

	struct fasync_struct *fsn_fa;    /* async notification */

	struct fsnotify_event *overflow_event;	/* Event we queue when the
						 * notification list is too
						 * full */

	/* groups can define private fields here or use the void *private */
	union {
		void *private;
#ifdef CONFIG_INOTIFY_USER
		struct inotify_group_private_data {
			spinlock_t	idr_lock;
			struct idr      idr;
			struct user_struct      *user;
		} inotify_data;
#endif
#ifdef CONFIG_FANOTIFY
		struct fanotify_group_private_data {
#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
			/* allows a group to block waiting for a userspace response */
			spinlock_t access_lock;
			struct list_head access_list;
			wait_queue_head_t access_waitq;
#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
			int f_flags;
			unsigned int max_marks;
			struct user_struct *user;
		} fanotify_data;
#endif /* CONFIG_FANOTIFY */
	};
};

/* 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

/*
 * A mark is simply an object 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.
 *
 * Text in brackets is showing the lock(s) protecting modifications of a
 * particular entry. obj_lock means either inode->i_lock or
 * mnt->mnt_root->d_lock depending on the mark type.
 */
struct fsnotify_mark {
	/* Mask this mark is for [mark->lock, group->mark_mutex] */
	__u32 mask;
	/* We hold one for presence in g_list. Also one ref for each 'thing'
	 * in kernel that found and may be using this mark. */
	atomic_t refcnt;
	/* Group this mark is for. Set on mark creation, stable until last ref
	 * is dropped */
	struct fsnotify_group *group;
	/* List of marks by group->i_fsnotify_marks. Also reused for queueing
	 * mark into destroy_list when it's waiting for the end of SRCU period
	 * before it can be freed. [group->mark_mutex] */
	struct list_head g_list;
	/* Protects inode / mnt pointers, flags, masks */
	spinlock_t lock;
	/* List of marks for inode / vfsmount [obj_lock] */
	struct hlist_node obj_list;
	union {	/* Object pointer [mark->lock, group->mark_mutex] */
		struct inode *inode;	/* inode this mark is associated with */
		struct vfsmount *mnt;	/* vfsmount this mark is associated with */
	};
	/* Events types to ignore [mark->lock, group->mark_mutex] */
	__u32 ignored_mask;
#define FSNOTIFY_MARK_FLAG_INODE		0x01
#define FSNOTIFY_MARK_FLAG_VFSMOUNT		0x02
#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED	0x04
#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY	0x08
#define FSNOTIFY_MARK_FLAG_ALIVE		0x10
#define FSNOTIFY_MARK_FLAG_ATTACHED		0x20
	unsigned int flags;		/* flags [mark->lock] */
	void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
};

#ifdef CONFIG_FSNOTIFY

/* called from the vfs helpers */

/* main fsnotify call to send events */
extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
		    const unsigned char *name, u32 cookie);
extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
extern void __fsnotify_inode_delete(struct inode *inode);
extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
extern u32 fsnotify_get_cookie(void);

static inline int fsnotify_inode_watches_children(struct inode *inode)
{
	/* FS_EVENT_ON_CHILD is set if the inode may care */
	if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
		return 0;
	/* this inode might care about child events, does it care about the
	 * specific set of events that can happen on a child? */
	return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
}

/*
 * Update the dentry with a flag indicating the interest of its parent to receive
 * filesystem events when those events happens to this dentry->d_inode.
 */
static inline void fsnotify_update_flags(struct dentry *dentry)
{
	assert_spin_locked(&dentry->d_lock);

	/*
	 * Serialisation of setting PARENT_WATCHED on the dentries is provided
	 * by d_lock. If inotify_inode_watched changes after we have taken
	 * d_lock, the following __fsnotify_update_child_dentry_flags call will
	 * find our entry, so it will spin until we complete here, and update
	 * us with the new state.
	 */
	if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
		dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
	else
		dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
}

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

/* create a new group */
extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
/* get reference to a group */
extern void fsnotify_get_group(struct fsnotify_group *group);
/* drop reference on a group from fsnotify_alloc_group */
extern void fsnotify_put_group(struct fsnotify_group *group);
/* group destruction begins, stop queuing new events */
extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
/* destroy group */
extern void fsnotify_destroy_group(struct fsnotify_group *group);
/* fasync handler function */
extern int fsnotify_fasync(int fd, struct file *file, int on);
/* Free event from memory */
extern void fsnotify_destroy_event(struct fsnotify_group *group,
				   struct fsnotify_event *event);
/* attach the event to the group notification queue */
extern int fsnotify_add_event(struct fsnotify_group *group,
			      struct fsnotify_event *event,
			      int (*merge)(struct list_head *,
					   struct fsnotify_event *));
/* true if the group notification queue is empty */
extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
/* return, but do not dequeue the first event on the notification queue */
extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
/* return AND dequeue the first event on the notification queue */
extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);

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

/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
/* 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 *mark, void (*free_mark)(struct fsnotify_mark *mark));
/* find (and take a reference) to a mark associated with group and inode */
extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
/* find (and take a reference) to a mark associated with group and vfsmount */
extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
/* copy the values from old into new */
extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
/* set the ignored_mask of a mark */
extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
/* set the mask of a mark (might pin the object into memory */
extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
/* attach the mark to both the group and the inode */
extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
			     struct inode *inode, struct vfsmount *mnt, int allow_dups);
extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
				    struct inode *inode, struct vfsmount *mnt, int allow_dups);
/* given a group and a mark, flag mark to be freed when all references are dropped */
extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
				  struct fsnotify_group *group);
/* detach mark from inode / mount list, group list, drop inode reference */
extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
/* free mark */
extern void fsnotify_free_mark(struct fsnotify_mark *mark);
/* run all the marks in a group, and clear all of the vfsmount marks */
extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
/* run all the marks in a group, and clear all of the inode marks */
extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
extern void fsnotify_get_mark(struct fsnotify_mark *mark);
extern void fsnotify_put_mark(struct fsnotify_mark *mark);
extern void fsnotify_unmount_inodes(struct super_block *sb);

/* put here because inotify does some weird stuff when destroying watches */
extern void fsnotify_init_event(struct fsnotify_event *event,
				struct inode *to_tell, u32 mask);

#else

static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
			   const unsigned char *name, u32 cookie)
{
	return 0;
}

static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
{
	return 0;
}

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

static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
{}

static inline void fsnotify_update_flags(struct dentry *dentry)
{}

static inline u32 fsnotify_get_cookie(void)
{
	return 0;
}

static inline void fsnotify_unmount_inodes(struct super_block *sb)
{}

#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
63c882a0	12	#include <linux/idr.h> /* inotify uses this */
90586523 EP	13	#include <linux/fs.h> /* struct inode */
	14	#include <linux/list.h>
	15	#include <linux/path.h> /* struct path */
	16	#include <linux/spinlock.h>
	17	#include <linux/types.h>
60063497	18	#include <linux/atomic.h>
90586523 EP	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
c4ec54b4 EP	43	#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
	44	#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
	45
8c1934c8	46	#define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
b29866aa	47	#define FS_ISDIR 0x40000000 /* event occurred against dir */
90586523 EP	48	#define FS_IN_ONESHOT 0x80000000 /* only send event once */
	49
	50	#define FS_DN_RENAME 0x10000000 /* file renamed */
	51	#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
	52
c28f7e56 EP	53	/* This inode cares about things that happen to its children. Always set for
	54	* dnotify and inotify. */
	55	#define FS_EVENT_ON_CHILD 0x08000000
	56
	57	/* This is a list of all events that may get sent to a parernt based on fs event
	58	* happening to inodes inside that directory */
	59	#define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS \| FS_MODIFY \| FS_ATTRIB \|\
	60	FS_CLOSE_WRITE \| FS_CLOSE_NOWRITE \| FS_OPEN \|\
	61	FS_MOVED_FROM \| FS_MOVED_TO \| FS_CREATE \|\
a4f9a9a6	62	FS_DELETE \| FS_OPEN_PERM \| FS_ACCESS_PERM)
c28f7e56	63
e9fd702a EP	64	#define FS_MOVE (FS_MOVED_FROM \| FS_MOVED_TO)
e9fd702a EP	65
ff8bcbd0 EP	66	#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM \| FS_ACCESS_PERM)
ff8bcbd0 EP	67
20dee624 EP	68	#define ALL_FSNOTIFY_EVENTS (FS_ACCESS \| FS_MODIFY \| FS_ATTRIB \| \
	69	FS_CLOSE_WRITE \| FS_CLOSE_NOWRITE \| FS_OPEN \| \
	70	FS_MOVED_FROM \| FS_MOVED_TO \| FS_CREATE \| \
	71	FS_DELETE \| FS_DELETE_SELF \| FS_MOVE_SELF \| \
	72	FS_UNMOUNT \| FS_Q_OVERFLOW \| FS_IN_IGNORED \| \
	73	FS_OPEN_PERM \| FS_ACCESS_PERM \| FS_EXCL_UNLINK \| \
b29866aa	74	FS_ISDIR \| FS_IN_ONESHOT \| FS_DN_RENAME \| \
20dee624 EP	75	FS_DN_MULTISHOT \| FS_EVENT_ON_CHILD)
20dee624 EP	76
90586523 EP	77	struct fsnotify_group;
90586523 EP	78	struct fsnotify_event;
e61ce867	79	struct fsnotify_mark;
e4aff117	80	struct fsnotify_event_private_data;
7053aee2	81	struct fsnotify_fname;
90586523 EP	82
	83	/*
	84	* Each group much define these ops. The fsnotify infrastructure will call
	85	* these operations for each relevant group.
	86	*
	87	* handle_event - main call for a group to handle an fs event
	88	* free_group_priv - called when a group refcnt hits 0 to clean up the private union
6960b0d9 LS	89	* freeing_mark - called when a mark is being destroyed for some reason. The group
	90	* MUST be holding a reference on each mark and that reference must be
	91	* dropped in this function. inotify uses this function to send
	92	* userspace messages that marks have been removed.
90586523 EP	93	*/
90586523 EP	94	struct fsnotify_ops {
ce8f76fb	95	int (handle_event)(struct fsnotify_group group,
7053aee2	96	struct inode *inode,
ce8f76fb EP	97	struct fsnotify_mark *inode_mark,
ce8f76fb EP	98	struct fsnotify_mark *vfsmount_mark,
7053aee2	99	u32 mask, void *data, int data_type,
45a22f4c	100	const unsigned char *file_name, u32 cookie);
90586523	101	void (free_group_priv)(struct fsnotify_group group);
841bdc10	102	void (freeing_mark)(struct fsnotify_mark mark, struct fsnotify_group *group);
7053aee2 JK	103	void (free_event)(struct fsnotify_event event);
	104	};
	105
	106	/*
	107	* all of the information about the original object we want to now send to
	108	* a group. If you want to carry more info from the accessing task to the
	109	* listener this structure is where you need to be adding fields.
	110	*/
	111	struct fsnotify_event {
	112	struct list_head list;
	113	/* inode may ONLY be dereferenced during handle_event(). */
	114	struct inode inode; / either the inode the event happened to or its parent */
	115	u32 mask; /* the type of access, bitwise OR for FS_* event types */
90586523 EP	116	};
	117
	118	/*
	119	* A group is a "thing" that wants to receive notification about filesystem
	120	* events. The mask holds the subset of event types this group cares about.
	121	* refcnt on a group is up to the implementor and at any moment if it goes 0
	122	* everything will be cleaned up.
	123	*/
	124	struct fsnotify_group {
90586523 EP	125	/*
	126	* How the refcnt is used is up to each group. When the refcnt hits 0
	127	* fsnotify will clean up all of the resources associated with this group.
	128	* As an example, the dnotify group will always have a refcnt=1 and that
	129	* will never change. Inotify, on the other hand, has a group per
	130	* inotify_init() and the refcnt will hit 0 only when that fd has been
	131	* closed.
	132	*/
	133	atomic_t refcnt; /* things with interest in this group */
90586523 EP	134
	135	const struct fsnotify_ops ops; / how this group handles things */
	136
a2d8bc6c EP	137	/* needed to send notification to userspace */
	138	struct mutex notification_mutex; /* protect the notification_list */
	139	struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
	140	wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
	141	unsigned int q_len; /* events on the queue */
	142	unsigned int max_events; /* maximum events allowed on the list */
6ad2d4e3 EP	143	/*
	144	* Valid fsnotify group priorities. Events are send in order from highest
	145	* priority to lowest priority. We default to the lowest priority.
	146	*/
	147	#define FS_PRIO_0 0 /* normal notifiers, no permissions */
	148	#define FS_PRIO_1 1 /* fanotify content based access control */
	149	#define FS_PRIO_2 2 /* fanotify pre-content access */
	150	unsigned int priority;
12703dbf	151	bool shutdown; /* group is being shut down, don't queue more events */
a2d8bc6c	152
e61ce867	153	/* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
986ab098	154	struct mutex mark_mutex; /* protect marks_list */
841bdc10	155	atomic_t num_marks; /* 1 for each mark and 1 for not being
3be25f49 EP	156	* past the point of no return when freeing
3be25f49 EP	157	* a group */
e61ce867	158	struct list_head marks_list; /* all inode marks for this group */
3be25f49	159
7053aee2 JK	160	struct fasync_struct fsn_fa; / async notification */
7053aee2 JK	161
ff57cd58	162	struct fsnotify_event overflow_event; / Event we queue when the
7053aee2 JK	163	* notification list is too
7053aee2 JK	164	* full */
0a6b6bd5	165
90586523 EP	166	/* groups can define private fields here or use the void private /
	167	union {
	168	void *private;
63c882a0 EP	169	#ifdef CONFIG_INOTIFY_USER
	170	struct inotify_group_private_data {
	171	spinlock_t idr_lock;
	172	struct idr idr;
63c882a0 EP	173	struct user_struct *user;
63c882a0 EP	174	} inotify_data;
9e66e423	175	#endif
80af2588	176	#ifdef CONFIG_FANOTIFY
9e66e423	177	struct fanotify_group_private_data {
80af2588	178	#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
9e66e423	179	/* allows a group to block waiting for a userspace response */
9573f793	180	spinlock_t access_lock;
9e66e423 EP	181	struct list_head access_list;
9e66e423 EP	182	wait_queue_head_t access_waitq;
80af2588 EP	183	#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
80af2588 EP	184	int f_flags;
e7099d8a	185	unsigned int max_marks;
4afeff85	186	struct user_struct *user;
9e66e423	187	} fanotify_data;
80af2588	188	#endif /* CONFIG_FANOTIFY */
90586523 EP	189	};
	190	};
	191
90586523 EP	192	/* when calling fsnotify tell it if the data is a path or inode */
90586523 EP	193	#define FSNOTIFY_EVENT_NONE 0
2069601b	194	#define FSNOTIFY_EVENT_PATH 1
90586523	195	#define FSNOTIFY_EVENT_INODE 2
90586523	196
3be25f49	197	/*
1e39fc01	198	* A mark is simply an object attached to an in core inode which allows an
3be25f49 EP	199	* fsnotify listener to indicate they are either no longer interested in events
	200	* of a type matching mask or only interested in those events.
	201	*
1e39fc01 JK	202	* These are flushed when an inode is evicted from core and may be flushed
	203	* when the inode is modified (as seen by fsnotify_access). Some fsnotify
	204	* users (such as dnotify) will flush these when the open fd is closed and not
	205	* at inode eviction or modification.
	206	*
	207	* Text in brackets is showing the lock(s) protecting modifications of a
	208	* particular entry. obj_lock means either inode->i_lock or
	209	* mnt->mnt_root->d_lock depending on the mark type.
3be25f49	210	*/
e61ce867	211	struct fsnotify_mark {
1e39fc01 JK	212	/* Mask this mark is for [mark->lock, group->mark_mutex] */
	213	__u32 mask;
	214	/* We hold one for presence in g_list. Also one ref for each 'thing'
3be25f49	215	* in kernel that found and may be using this mark. */
1e39fc01 JK	216	atomic_t refcnt;
	217	/* Group this mark is for. Set on mark creation, stable until last ref
	218	* is dropped */
	219	struct fsnotify_group *group;
	220	/* List of marks by group->i_fsnotify_marks. Also reused for queueing
	221	* mark into destroy_list when it's waiting for the end of SRCU period
	222	* before it can be freed. [group->mark_mutex] */
13d34ac6	223	struct list_head g_list;
1e39fc01 JK	224	/* Protects inode / mnt pointers, flags, masks */
	225	spinlock_t lock;
	226	/* List of marks for inode / vfsmount [obj_lock] */
	227	struct hlist_node obj_list;
1e39fc01	228	union { /* Object pointer [mark->lock, group->mark_mutex] */
0809ab69 JK	229	struct inode inode; / inode this mark is associated with */
0809ab69 JK	230	struct vfsmount mnt; / vfsmount this mark is associated with */
2823e04d	231	};
1e39fc01 JK	232	/* Events types to ignore [mark->lock, group->mark_mutex] */
1e39fc01 JK	233	__u32 ignored_mask;
90b1e7a5 EP	234	#define FSNOTIFY_MARK_FLAG_INODE 0x01
	235	#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
	236	#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
c908370f	237	#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
700307a2	238	#define FSNOTIFY_MARK_FLAG_ALIVE 0x10
4712e722	239	#define FSNOTIFY_MARK_FLAG_ATTACHED 0x20
1e39fc01	240	unsigned int flags; /* flags [mark->lock] */
841bdc10	241	void (free_mark)(struct fsnotify_mark mark); /* called on final put+free */
3be25f49 EP	242	};
3be25f49 EP	243
90586523 EP	244	#ifdef CONFIG_FSNOTIFY
	245
	246	/* called from the vfs helpers */
	247
	248	/* main fsnotify call to send events */
c4ec54b4 EP	249	extern int fsnotify(struct inode to_tell, __u32 mask, void data, int data_is,
c4ec54b4 EP	250	const unsigned char *name, u32 cookie);
52420392	251	extern int __fsnotify_parent(struct path path, struct dentry dentry, __u32 mask);
3be25f49	252	extern void __fsnotify_inode_delete(struct inode *inode);
ca9c726e	253	extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
47882c6f	254	extern u32 fsnotify_get_cookie(void);
90586523	255
c28f7e56 EP	256	static inline int fsnotify_inode_watches_children(struct inode *inode)
	257	{
	258	/* FS_EVENT_ON_CHILD is set if the inode may care */
	259	if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
	260	return 0;
	261	/* this inode might care about child events, does it care about the
	262	* specific set of events that can happen on a child? */
	263	return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
	264	}
	265
	266	/*
	267	* Update the dentry with a flag indicating the interest of its parent to receive
	268	* filesystem events when those events happens to this dentry->d_inode.
	269	*/
affda484	270	static inline void fsnotify_update_flags(struct dentry *dentry)
c28f7e56	271	{
c28f7e56 EP	272	assert_spin_locked(&dentry->d_lock);
c28f7e56 EP	273
b5c84bf6 NP	274	/*
	275	* Serialisation of setting PARENT_WATCHED on the dentries is provided
	276	* by d_lock. If inotify_inode_watched changes after we have taken
	277	* d_lock, the following __fsnotify_update_child_dentry_flags call will
	278	* find our entry, so it will spin until we complete here, and update
	279	* us with the new state.
	280	*/
affda484	281	if (fsnotify_inode_watches_children(dentry->d_parent->d_inode))
c28f7e56 EP	282	dentry->d_flags \|= DCACHE_FSNOTIFY_PARENT_WATCHED;
	283	else
	284	dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
	285	}
	286
90586523 EP	287	/* called from fsnotify listeners, such as fanotify or dnotify */
90586523 EP	288
98612952	289	/* create a new group */
0d2e2a1d	290	extern struct fsnotify_group fsnotify_alloc_group(const struct fsnotify_ops ops);
98612952 LS	291	/* get reference to a group */
98612952 LS	292	extern void fsnotify_get_group(struct fsnotify_group *group);
ffab8340	293	/* drop reference on a group from fsnotify_alloc_group */
90586523	294	extern void fsnotify_put_group(struct fsnotify_group *group);
12703dbf JK	295	/* group destruction begins, stop queuing new events */
12703dbf JK	296	extern void fsnotify_group_stop_queueing(struct fsnotify_group *group);
d8153d4d LS	297	/* destroy group */
d8153d4d LS	298	extern void fsnotify_destroy_group(struct fsnotify_group *group);
0a6b6bd5 EP	299	/* fasync handler function */
0a6b6bd5 EP	300	extern int fsnotify_fasync(int fd, struct file *file, int on);
7053aee2 JK	301	/* Free event from memory */
	302	extern void fsnotify_destroy_event(struct fsnotify_group *group,
	303	struct fsnotify_event *event);
a2d8bc6c	304	/* attach the event to the group notification queue */
8ba8fa91 JK	305	extern int fsnotify_add_event(struct fsnotify_group *group,
	306	struct fsnotify_event *event,
	307	int (merge)(struct list_head ,
	308	struct fsnotify_event *));
a2d8bc6c EP	309	/* true if the group notification queue is empty */
	310	extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
	311	/* return, but do not dequeue the first event on the notification queue */
8ba8fa91	312	extern struct fsnotify_event fsnotify_peek_first_event(struct fsnotify_group group);
e4aff117	313	/* return AND dequeue the first event on the notification queue */
8ba8fa91	314	extern struct fsnotify_event fsnotify_remove_first_event(struct fsnotify_group group);
a2d8bc6c	315
3be25f49 EP	316	/* functions used to manipulate the marks attached to inodes */
3be25f49 EP	317
0d48b7f0 EP	318	/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
0d48b7f0 EP	319	extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
3be25f49 EP	320	/* run all marks associated with an inode and update inode->i_fsnotify_mask */
3be25f49 EP	321	extern void fsnotify_recalc_inode_mask(struct inode *inode);
841bdc10	322	extern void fsnotify_init_mark(struct fsnotify_mark mark, void (free_mark)(struct fsnotify_mark *mark));
3be25f49	323	/* find (and take a reference) to a mark associated with group and inode */
5444e298	324	extern struct fsnotify_mark fsnotify_find_inode_mark(struct fsnotify_group group, struct inode *inode);
1c529063 EP	325	/* find (and take a reference) to a mark associated with group and vfsmount */
1c529063 EP	326	extern struct fsnotify_mark fsnotify_find_vfsmount_mark(struct fsnotify_group group, struct vfsmount *mnt);
9e1c7432	327	/* copy the values from old into new */
e61ce867	328	extern void fsnotify_duplicate_mark(struct fsnotify_mark new, struct fsnotify_mark old);
33af5e32 EP	329	/* set the ignored_mask of a mark */
33af5e32 EP	330	extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
90b1e7a5 EP	331	/* set the mask of a mark (might pin the object into memory */
90b1e7a5 EP	332	extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
3be25f49	333	/* attach the mark to both the group and the inode */
5444e298 EP	334	extern int fsnotify_add_mark(struct fsnotify_mark mark, struct fsnotify_group group,
5444e298 EP	335	struct inode inode, struct vfsmount mnt, int allow_dups);
d5a335b8 LS	336	extern int fsnotify_add_mark_locked(struct fsnotify_mark mark, struct fsnotify_group group,
d5a335b8 LS	337	struct inode inode, struct vfsmount mnt, int allow_dups);
e2a29943 LS	338	/* given a group and a mark, flag mark to be freed when all references are dropped */
	339	extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
	340	struct fsnotify_group *group);
4712e722 JK	341	/* detach mark from inode / mount list, group list, drop inode reference */
	342	extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
	343	/* free mark */
	344	extern void fsnotify_free_mark(struct fsnotify_mark *mark);
4d92604c EP	345	/* run all the marks in a group, and clear all of the vfsmount marks */
	346	extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
	347	/* run all the marks in a group, and clear all of the inode marks */
	348	extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
	349	/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
	350	extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
841bdc10 EP	351	extern void fsnotify_get_mark(struct fsnotify_mark *mark);
841bdc10 EP	352	extern void fsnotify_put_mark(struct fsnotify_mark *mark);
74278da9	353	extern void fsnotify_unmount_inodes(struct super_block *sb);
3be25f49	354
90586523	355	/* put here because inotify does some weird stuff when destroying watches */
7053aee2 JK	356	extern void fsnotify_init_event(struct fsnotify_event *event,
7053aee2 JK	357	struct inode *to_tell, u32 mask);
b4e4e140	358
90586523 EP	359	#else
90586523 EP	360
c4ec54b4 EP	361	static inline int fsnotify(struct inode to_tell, __u32 mask, void data, int data_is,
	362	const unsigned char *name, u32 cookie)
	363	{
	364	return 0;
	365	}
3be25f49	366
52420392 EP	367	static inline int __fsnotify_parent(struct path path, struct dentry dentry, __u32 mask)
	368	{
	369	return 0;
	370	}
c28f7e56	371
3be25f49 EP	372	static inline void __fsnotify_inode_delete(struct inode *inode)
	373	{}
	374
ca9c726e AG	375	static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
	376	{}
	377
affda484	378	static inline void fsnotify_update_flags(struct dentry *dentry)
c28f7e56 EP	379	{}
c28f7e56 EP	380
47882c6f EP	381	static inline u32 fsnotify_get_cookie(void)
	382	{
	383	return 0;
	384	}
	385
74278da9	386	static inline void fsnotify_unmount_inodes(struct super_block *sb)
164bc619 EP	387	{}
164bc619 EP	388
90586523 EP	389	#endif /* CONFIG_FSNOTIFY */
	390
	391	#endif /* __KERNEL __ */
	392
	393	#endif /* __LINUX_FSNOTIFY_BACKEND_H */