Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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/idr.h> /* inotify uses this */
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>
18#include <linux/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_OPEN_PERM 0x00010000 /* open event in an permission hook */
44#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
45
46#define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
47#define FS_ISDIR 0x40000000 /* event occurred against dir */
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
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 |\
62 FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM)
63
64#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
65
66#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
67
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 | \
74 FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
75 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
76
77struct fsnotify_group;
78struct fsnotify_event;
79struct fsnotify_mark;
80struct fsnotify_event_private_data;
81struct fsnotify_fname;
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
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.
93 */
94struct fsnotify_ops {
95 int (*handle_event)(struct fsnotify_group *group,
96 struct inode *inode,
97 struct fsnotify_mark *inode_mark,
98 struct fsnotify_mark *vfsmount_mark,
99 u32 mask, void *data, int data_type,
100 const unsigned char *file_name, u32 cookie);
101 void (*free_group_priv)(struct fsnotify_group *group);
102 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
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 */
111struct 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 */
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 */
124struct fsnotify_group {
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 */
134
135 const struct fsnotify_ops *ops; /* how this group handles things */
136
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 */
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;
151
152 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
153 struct mutex mark_mutex; /* protect marks_list */
154 atomic_t num_marks; /* 1 for each mark and 1 for not being
155 * past the point of no return when freeing
156 * a group */
157 struct list_head marks_list; /* all inode marks for this group */
158
159 struct fasync_struct *fsn_fa; /* async notification */
160
161 struct fsnotify_event *overflow_event; /* Event we queue when the
162 * notification list is too
163 * full */
164
165 /* groups can define private fields here or use the void *private */
166 union {
167 void *private;
168#ifdef CONFIG_INOTIFY_USER
169 struct inotify_group_private_data {
170 spinlock_t idr_lock;
171 struct idr idr;
172 struct user_struct *user;
173 } inotify_data;
174#endif
175#ifdef CONFIG_FANOTIFY
176 struct fanotify_group_private_data {
177#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
178 /* allows a group to block waiting for a userspace response */
179 spinlock_t access_lock;
180 struct list_head access_list;
181 wait_queue_head_t access_waitq;
182 atomic_t bypass_perm;
183#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
184 int f_flags;
185 unsigned int max_marks;
186 struct user_struct *user;
187 } fanotify_data;
188#endif /* CONFIG_FANOTIFY */
189 };
190};
191
192/* when calling fsnotify tell it if the data is a path or inode */
193#define FSNOTIFY_EVENT_NONE 0
194#define FSNOTIFY_EVENT_PATH 1
195#define FSNOTIFY_EVENT_INODE 2
196
197/*
198 * A mark is simply an object attached to an in core inode which allows an
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 *
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.
210 */
211struct fsnotify_mark {
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'
215 * in kernel that found and may be using this mark. */
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] */
223 struct list_head g_list;
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;
228 union { /* Object pointer [mark->lock, group->mark_mutex] */
229 struct inode *inode; /* inode this mark is associated with */
230 struct vfsmount *mnt; /* vfsmount this mark is associated with */
231 };
232 /* Events types to ignore [mark->lock, group->mark_mutex] */
233 __u32 ignored_mask;
234#define FSNOTIFY_MARK_FLAG_INODE 0x01
235#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
236#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
237#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
238#define FSNOTIFY_MARK_FLAG_ALIVE 0x10
239#define FSNOTIFY_MARK_FLAG_ATTACHED 0x20
240 unsigned int flags; /* flags [mark->lock] */
241 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
242};
243
244#ifdef CONFIG_FSNOTIFY
245
246/* called from the vfs helpers */
247
248/* main fsnotify call to send events */
249extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
250 const unsigned char *name, u32 cookie);
251extern int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
252extern void __fsnotify_inode_delete(struct inode *inode);
253extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
254extern u32 fsnotify_get_cookie(void);
255
256static 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 */
270static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
271{
272 struct dentry *parent;
273
274 assert_spin_locked(&dentry->d_lock);
275
276 /*
277 * Serialisation of setting PARENT_WATCHED on the dentries is provided
278 * by d_lock. If inotify_inode_watched changes after we have taken
279 * d_lock, the following __fsnotify_update_child_dentry_flags call will
280 * find our entry, so it will spin until we complete here, and update
281 * us with the new state.
282 */
283 parent = dentry->d_parent;
284 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
285 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
286 else
287 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
288}
289
290/*
291 * fsnotify_d_instantiate - instantiate a dentry for inode
292 */
293static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
294{
295 if (!inode)
296 return;
297
298 spin_lock(&dentry->d_lock);
299 __fsnotify_update_dcache_flags(dentry);
300 spin_unlock(&dentry->d_lock);
301}
302
303/* called from fsnotify listeners, such as fanotify or dnotify */
304
305/* create a new group */
306extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
307/* get reference to a group */
308extern void fsnotify_get_group(struct fsnotify_group *group);
309/* drop reference on a group from fsnotify_alloc_group */
310extern void fsnotify_put_group(struct fsnotify_group *group);
311/* destroy group */
312extern void fsnotify_destroy_group(struct fsnotify_group *group);
313/* fasync handler function */
314extern int fsnotify_fasync(int fd, struct file *file, int on);
315/* Free event from memory */
316extern void fsnotify_destroy_event(struct fsnotify_group *group,
317 struct fsnotify_event *event);
318/* attach the event to the group notification queue */
319extern int fsnotify_add_event(struct fsnotify_group *group,
320 struct fsnotify_event *event,
321 int (*merge)(struct list_head *,
322 struct fsnotify_event *));
323/* Remove passed event from groups notification queue */
324extern void fsnotify_remove_event(struct fsnotify_group *group, struct fsnotify_event *event);
325/* true if the group notification queue is empty */
326extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
327/* return, but do not dequeue the first event on the notification queue */
328extern struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group);
329/* return AND dequeue the first event on the notification queue */
330extern struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group);
331
332/* functions used to manipulate the marks attached to inodes */
333
334/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
335extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
336/* run all marks associated with an inode and update inode->i_fsnotify_mask */
337extern void fsnotify_recalc_inode_mask(struct inode *inode);
338extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
339/* find (and take a reference) to a mark associated with group and inode */
340extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
341/* find (and take a reference) to a mark associated with group and vfsmount */
342extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
343/* copy the values from old into new */
344extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
345/* set the ignored_mask of a mark */
346extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
347/* set the mask of a mark (might pin the object into memory */
348extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
349/* attach the mark to both the group and the inode */
350extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
351 struct inode *inode, struct vfsmount *mnt, int allow_dups);
352extern int fsnotify_add_mark_locked(struct fsnotify_mark *mark, struct fsnotify_group *group,
353 struct inode *inode, struct vfsmount *mnt, int allow_dups);
354/* given a group and a mark, flag mark to be freed when all references are dropped */
355extern void fsnotify_destroy_mark(struct fsnotify_mark *mark,
356 struct fsnotify_group *group);
357/* detach mark from inode / mount list, group list, drop inode reference */
358extern void fsnotify_detach_mark(struct fsnotify_mark *mark);
359/* free mark */
360extern void fsnotify_free_mark(struct fsnotify_mark *mark);
361/* run all the marks in a group, and clear all of the vfsmount marks */
362extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
363/* run all the marks in a group, and clear all of the inode marks */
364extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
365/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
366extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
367/* run all the marks in a group, and flag them to be freed */
368extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
369extern void fsnotify_get_mark(struct fsnotify_mark *mark);
370extern void fsnotify_put_mark(struct fsnotify_mark *mark);
371extern void fsnotify_unmount_inodes(struct super_block *sb);
372
373/* put here because inotify does some weird stuff when destroying watches */
374extern void fsnotify_init_event(struct fsnotify_event *event,
375 struct inode *to_tell, u32 mask);
376
377#else
378
379static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
380 const unsigned char *name, u32 cookie)
381{
382 return 0;
383}
384
385static inline int __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
386{
387 return 0;
388}
389
390static inline void __fsnotify_inode_delete(struct inode *inode)
391{}
392
393static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
394{}
395
396static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
397{}
398
399static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
400{}
401
402static inline u32 fsnotify_get_cookie(void)
403{
404 return 0;
405}
406
407static inline void fsnotify_unmount_inodes(struct super_block *sb)
408{}
409
410#endif /* CONFIG_FSNOTIFY */
411
412#endif /* __KERNEL __ */
413
414#endif /* __LINUX_FSNOTIFY_BACKEND_H */