178 lines
6.5 KiB
C
178 lines
6.5 KiB
C
![]() |
/*
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* Filesystem access notification for Linux
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*
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* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
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*/
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#ifndef __LINUX_FSNOTIFY_BACKEND_H
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#define __LINUX_FSNOTIFY_BACKEND_H
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#ifdef __KERNEL__
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#include <linux/fs.h> /* struct inode */
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#include <linux/list.h>
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#include <linux/path.h> /* struct path */
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <asm/atomic.h>
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/*
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* IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
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* convert between them. dnotify only needs conversion at watch creation
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* so no perf loss there. fanotify isn't defined yet, so it can use the
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* wholes if it needs more events.
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*/
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#define FS_ACCESS 0x00000001 /* File was accessed */
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#define FS_MODIFY 0x00000002 /* File was modified */
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#define FS_ATTRIB 0x00000004 /* Metadata changed */
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#define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
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#define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
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#define FS_OPEN 0x00000020 /* File was opened */
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#define FS_MOVED_FROM 0x00000040 /* File was moved from X */
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#define FS_MOVED_TO 0x00000080 /* File was moved to Y */
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#define FS_CREATE 0x00000100 /* Subfile was created */
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#define FS_DELETE 0x00000200 /* Subfile was deleted */
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#define FS_DELETE_SELF 0x00000400 /* Self was deleted */
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#define FS_MOVE_SELF 0x00000800 /* Self was moved */
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#define FS_UNMOUNT 0x00002000 /* inode on umount fs */
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#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
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#define FS_IN_IGNORED 0x00008000 /* last inotify event here */
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#define FS_IN_ISDIR 0x40000000 /* event occurred against dir */
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#define FS_IN_ONESHOT 0x80000000 /* only send event once */
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#define FS_DN_RENAME 0x10000000 /* file renamed */
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#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
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struct fsnotify_group;
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struct fsnotify_event;
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/*
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* Each group much define these ops. The fsnotify infrastructure will call
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* these operations for each relevant group.
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*
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* handle_event - main call for a group to handle an fs event
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* free_group_priv - called when a group refcnt hits 0 to clean up the private union
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*/
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struct fsnotify_ops {
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int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event);
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void (*free_group_priv)(struct fsnotify_group *group);
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};
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/*
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* A group is a "thing" that wants to receive notification about filesystem
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* events. The mask holds the subset of event types this group cares about.
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* refcnt on a group is up to the implementor and at any moment if it goes 0
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* everything will be cleaned up.
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*/
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struct fsnotify_group {
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/*
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* global list of all groups receiving events from fsnotify.
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* anchored by fsnotify_groups and protected by either fsnotify_grp_mutex
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* or fsnotify_grp_srcu depending on write vs read.
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*/
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struct list_head group_list;
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/*
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* Defines all of the event types in which this group is interested.
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* This mask is a bitwise OR of the FS_* events from above. Each time
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* this mask changes for a group (if it changes) the correct functions
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* must be called to update the global structures which indicate global
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* interest in event types.
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*/
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__u32 mask;
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/*
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* How the refcnt is used is up to each group. When the refcnt hits 0
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* fsnotify will clean up all of the resources associated with this group.
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* As an example, the dnotify group will always have a refcnt=1 and that
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* will never change. Inotify, on the other hand, has a group per
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* inotify_init() and the refcnt will hit 0 only when that fd has been
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* closed.
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*/
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atomic_t refcnt; /* things with interest in this group */
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unsigned int group_num; /* simply prevents accidental group collision */
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const struct fsnotify_ops *ops; /* how this group handles things */
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/* prevents double list_del of group_list. protected by global fsnotify_gr_mutex */
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bool on_group_list;
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/* groups can define private fields here or use the void *private */
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union {
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void *private;
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};
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};
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/*
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* all of the information about the original object we want to now send to
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* a group. If you want to carry more info from the accessing task to the
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* listener this structure is where you need to be adding fields.
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*/
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struct fsnotify_event {
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spinlock_t lock; /* protection for the associated event_holder and private_list */
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/* to_tell may ONLY be dereferenced during handle_event(). */
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struct inode *to_tell; /* either the inode the event happened to or its parent */
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/*
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* depending on the event type we should have either a path or inode
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* We hold a reference on path, but NOT on inode. Since we have the ref on
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* the path, it may be dereferenced at any point during this object's
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* lifetime. That reference is dropped when this object's refcnt hits
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* 0. If this event contains an inode instead of a path, the inode may
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* ONLY be used during handle_event().
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*/
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union {
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struct path path;
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struct inode *inode;
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};
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/* when calling fsnotify tell it if the data is a path or inode */
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#define FSNOTIFY_EVENT_NONE 0
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#define FSNOTIFY_EVENT_PATH 1
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#define FSNOTIFY_EVENT_INODE 2
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#define FSNOTIFY_EVENT_FILE 3
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int data_type; /* which of the above union we have */
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atomic_t refcnt; /* how many groups still are using/need to send this event */
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__u32 mask; /* the type of access, bitwise OR for FS_* event types */
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};
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#ifdef CONFIG_FSNOTIFY
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/* called from the vfs helpers */
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/* main fsnotify call to send events */
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extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is);
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/* called from fsnotify listeners, such as fanotify or dnotify */
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/* must call when a group changes its ->mask */
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extern void fsnotify_recalc_global_mask(void);
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/* get a reference to an existing or create a new group */
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extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num,
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__u32 mask,
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const struct fsnotify_ops *ops);
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/* drop reference on a group from fsnotify_obtain_group */
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extern void fsnotify_put_group(struct fsnotify_group *group);
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/* take a reference to an event */
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extern void fsnotify_get_event(struct fsnotify_event *event);
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extern void fsnotify_put_event(struct fsnotify_event *event);
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/* find private data previously attached to an event */
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extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group,
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struct fsnotify_event *event);
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/* put here because inotify does some weird stuff when destroying watches */
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extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
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void *data, int data_is);
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#else
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static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
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{}
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#endif /* CONFIG_FSNOTIFY */
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#endif /* __KERNEL __ */
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#endif /* __LINUX_FSNOTIFY_BACKEND_H */
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