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[net-next-2.6.git] / include / linux / fsnotify_backend.h
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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 */
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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
19#include <asm/atomic.h>
20
21/*
22 * IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
23 * convert between them. dnotify only needs conversion at watch creation
24 * so no perf loss there. fanotify isn't defined yet, so it can use the
25 * wholes if it needs more events.
26 */
27#define FS_ACCESS 0x00000001 /* File was accessed */
28#define FS_MODIFY 0x00000002 /* File was modified */
29#define FS_ATTRIB 0x00000004 /* Metadata changed */
30#define FS_CLOSE_WRITE 0x00000008 /* Writtable file was closed */
31#define FS_CLOSE_NOWRITE 0x00000010 /* Unwrittable file closed */
32#define FS_OPEN 0x00000020 /* File was opened */
33#define FS_MOVED_FROM 0x00000040 /* File was moved from X */
34#define FS_MOVED_TO 0x00000080 /* File was moved to Y */
35#define FS_CREATE 0x00000100 /* Subfile was created */
36#define FS_DELETE 0x00000200 /* Subfile was deleted */
37#define FS_DELETE_SELF 0x00000400 /* Self was deleted */
38#define FS_MOVE_SELF 0x00000800 /* Self was moved */
39
40#define FS_UNMOUNT 0x00002000 /* inode on umount fs */
41#define FS_Q_OVERFLOW 0x00004000 /* Event queued overflowed */
42#define FS_IN_IGNORED 0x00008000 /* last inotify event here */
43
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44#define FS_OPEN_PERM 0x00010000 /* open event in an permission hook */
45#define FS_ACCESS_PERM 0x00020000 /* access event in a permissions hook */
46
8c1934c8 47#define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */
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48#define FS_IN_ISDIR 0x40000000 /* event occurred against dir */
49#define FS_IN_ONESHOT 0x80000000 /* only send event once */
50
51#define FS_DN_RENAME 0x10000000 /* file renamed */
52#define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */
53
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54/* This inode cares about things that happen to its children. Always set for
55 * dnotify and inotify. */
56#define FS_EVENT_ON_CHILD 0x08000000
57
58/* This is a list of all events that may get sent to a parernt based on fs event
59 * happening to inodes inside that directory */
60#define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\
61 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
62 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
63 FS_DELETE)
64
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65#define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO)
66
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67#define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
68 FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
69 FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
70 FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
71 FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
72 FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
73 FS_IN_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
74 FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
75
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76struct fsnotify_group;
77struct fsnotify_event;
e61ce867 78struct fsnotify_mark;
e4aff117 79struct fsnotify_event_private_data;
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80
81/*
82 * Each group much define these ops. The fsnotify infrastructure will call
83 * these operations for each relevant group.
84 *
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85 * should_send_event - given a group, inode, and mask this function determines
86 * if the group is interested in this event.
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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
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89 * freeing-mark - this means that a mark has been flagged to die when everything
90 * finishes using it. The function is supplied with what must be a
91 * valid group and inode to use to clean up.
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92 */
93struct fsnotify_ops {
7b0a04fb 94 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode,
1968f5ee 95 struct fsnotify_mark *inode_mark,
ce8f76fb 96 struct fsnotify_mark *vfsmount_mark,
3a9b16b4 97 __u32 mask, void *data, int data_type);
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98 int (*handle_event)(struct fsnotify_group *group,
99 struct fsnotify_mark *inode_mark,
100 struct fsnotify_mark *vfsmount_mark,
3a9b16b4 101 struct fsnotify_event *event);
90586523 102 void (*free_group_priv)(struct fsnotify_group *group);
841bdc10 103 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group);
e4aff117 104 void (*free_event_priv)(struct fsnotify_event_private_data *priv);
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105};
106
107/*
108 * A group is a "thing" that wants to receive notification about filesystem
109 * events. The mask holds the subset of event types this group cares about.
110 * refcnt on a group is up to the implementor and at any moment if it goes 0
111 * everything will be cleaned up.
112 */
113struct fsnotify_group {
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114 /*
115 * How the refcnt is used is up to each group. When the refcnt hits 0
116 * fsnotify will clean up all of the resources associated with this group.
117 * As an example, the dnotify group will always have a refcnt=1 and that
118 * will never change. Inotify, on the other hand, has a group per
119 * inotify_init() and the refcnt will hit 0 only when that fd has been
120 * closed.
121 */
122 atomic_t refcnt; /* things with interest in this group */
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123
124 const struct fsnotify_ops *ops; /* how this group handles things */
125
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126 /* needed to send notification to userspace */
127 struct mutex notification_mutex; /* protect the notification_list */
128 struct list_head notification_list; /* list of event_holder this group needs to send to userspace */
129 wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */
130 unsigned int q_len; /* events on the queue */
131 unsigned int max_events; /* maximum events allowed on the list */
132
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133 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */
134 spinlock_t mark_lock; /* protect marks_list */
841bdc10 135 atomic_t num_marks; /* 1 for each mark and 1 for not being
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136 * past the point of no return when freeing
137 * a group */
e61ce867 138 struct list_head marks_list; /* all inode marks for this group */
3be25f49 139
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140 /* groups can define private fields here or use the void *private */
141 union {
142 void *private;
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143#ifdef CONFIG_INOTIFY_USER
144 struct inotify_group_private_data {
145 spinlock_t idr_lock;
146 struct idr idr;
147 u32 last_wd;
148 struct fasync_struct *fa; /* async notification */
149 struct user_struct *user;
150 } inotify_data;
9e66e423 151#endif
80af2588 152#ifdef CONFIG_FANOTIFY
9e66e423 153 struct fanotify_group_private_data {
80af2588 154#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
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155 /* allows a group to block waiting for a userspace response */
156 struct mutex access_mutex;
157 struct list_head access_list;
158 wait_queue_head_t access_waitq;
2eebf582 159 bool bypass_perm; /* protected by access_mutex */
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160#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
161 int f_flags;
9e66e423 162 } fanotify_data;
80af2588 163#endif /* CONFIG_FANOTIFY */
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164 };
165};
166
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167/*
168 * A single event can be queued in multiple group->notification_lists.
169 *
170 * each group->notification_list will point to an event_holder which in turns points
171 * to the actual event that needs to be sent to userspace.
172 *
173 * Seemed cheaper to create a refcnt'd event and a small holder for every group
174 * than create a different event for every group
175 *
176 */
177struct fsnotify_event_holder {
178 struct fsnotify_event *event;
179 struct list_head event_list;
180};
181
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182/*
183 * Inotify needs to tack data onto an event. This struct lets us later find the
184 * correct private data of the correct group.
185 */
186struct fsnotify_event_private_data {
187 struct fsnotify_group *group;
188 struct list_head event_list;
189};
190
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191/*
192 * all of the information about the original object we want to now send to
193 * a group. If you want to carry more info from the accessing task to the
194 * listener this structure is where you need to be adding fields.
195 */
196struct fsnotify_event {
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197 /*
198 * If we create an event we are also likely going to need a holder
199 * to link to a group. So embed one holder in the event. Means only
200 * one allocation for the common case where we only have one group
201 */
202 struct fsnotify_event_holder holder;
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203 spinlock_t lock; /* protection for the associated event_holder and private_list */
204 /* to_tell may ONLY be dereferenced during handle_event(). */
205 struct inode *to_tell; /* either the inode the event happened to or its parent */
206 /*
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207 * depending on the event type we should have either a path or inode
208 * We hold a reference on path, but NOT on inode. Since we have the ref on
209 * the path, it may be dereferenced at any point during this object's
90586523 210 * lifetime. That reference is dropped when this object's refcnt hits
2069601b 211 * 0. If this event contains an inode instead of a path, the inode may
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212 * ONLY be used during handle_event().
213 */
214 union {
2069601b 215 struct path path;
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216 struct inode *inode;
217 };
218/* when calling fsnotify tell it if the data is a path or inode */
219#define FSNOTIFY_EVENT_NONE 0
2069601b 220#define FSNOTIFY_EVENT_PATH 1
90586523 221#define FSNOTIFY_EVENT_INODE 2
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222 int data_type; /* which of the above union we have */
223 atomic_t refcnt; /* how many groups still are using/need to send this event */
224 __u32 mask; /* the type of access, bitwise OR for FS_* event types */
62ffe5df 225
47882c6f 226 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */
59b0df21 227 const unsigned char *file_name;
62ffe5df 228 size_t name_len;
32c32632 229 struct pid *tgid;
e4aff117 230
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231#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS
232 __u32 response; /* userspace answer to question */
233#endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */
234
e4aff117 235 struct list_head private_data_list; /* groups can store private data here */
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236};
237
2823e04d 238/*
e61ce867 239 * Inode specific fields in an fsnotify_mark
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240 */
241struct fsnotify_inode_mark {
841bdc10 242 struct inode *inode; /* inode this mark is associated with */
e61ce867 243 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */
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244 struct list_head free_i_list; /* tmp list used when freeing this mark */
245};
246
4136510d 247/*
e61ce867 248 * Mount point specific fields in an fsnotify_mark
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249 */
250struct fsnotify_vfsmount_mark {
841bdc10 251 struct vfsmount *mnt; /* vfsmount this mark is associated with */
e61ce867 252 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */
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253 struct list_head free_m_list; /* tmp list used when freeing this mark */
254};
255
3be25f49 256/*
841bdc10 257 * a mark is simply an object attached to an in core inode which allows an
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258 * fsnotify listener to indicate they are either no longer interested in events
259 * of a type matching mask or only interested in those events.
260 *
261 * these are flushed when an inode is evicted from core and may be flushed
262 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users
263 * (such as dnotify) will flush these when the open fd is closed and not at
264 * inode eviction or modification.
265 */
e61ce867 266struct fsnotify_mark {
841bdc10 267 __u32 mask; /* mask this mark is for */
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268 /* we hold ref for each i_list and g_list. also one ref for each 'thing'
269 * in kernel that found and may be using this mark. */
270 atomic_t refcnt; /* active things looking at this mark */
841bdc10 271 struct fsnotify_group *group; /* group this mark is for */
e61ce867 272 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */
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273 spinlock_t lock; /* protect group and inode */
274 union {
275 struct fsnotify_inode_mark i;
4136510d 276 struct fsnotify_vfsmount_mark m;
2823e04d 277 };
33af5e32 278 __u32 ignored_mask; /* events types to ignore */
3be25f49 279 struct list_head free_g_list; /* tmp list used when freeing this mark */
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280#define FSNOTIFY_MARK_FLAG_INODE 0x01
281#define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02
282#define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04
c908370f 283#define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08
700307a2 284#define FSNOTIFY_MARK_FLAG_ALIVE 0x10
098cf2fc 285 unsigned int flags; /* vfsmount or inode mark? */
75c1be48 286 struct list_head destroy_list;
841bdc10 287 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */
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288};
289
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290#ifdef CONFIG_FSNOTIFY
291
292/* called from the vfs helpers */
293
294/* main fsnotify call to send events */
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295extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
296 const unsigned char *name, u32 cookie);
2069601b 297extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask);
3be25f49 298extern void __fsnotify_inode_delete(struct inode *inode);
ca9c726e 299extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
47882c6f 300extern u32 fsnotify_get_cookie(void);
90586523 301
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302static inline int fsnotify_inode_watches_children(struct inode *inode)
303{
304 /* FS_EVENT_ON_CHILD is set if the inode may care */
305 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD))
306 return 0;
307 /* this inode might care about child events, does it care about the
308 * specific set of events that can happen on a child? */
309 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD;
310}
311
312/*
313 * Update the dentry with a flag indicating the interest of its parent to receive
314 * filesystem events when those events happens to this dentry->d_inode.
315 */
316static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
317{
318 struct dentry *parent;
319
320 assert_spin_locked(&dcache_lock);
321 assert_spin_locked(&dentry->d_lock);
322
323 parent = dentry->d_parent;
e6ce3066 324 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode))
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325 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED;
326 else
327 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED;
328}
329
330/*
331 * fsnotify_d_instantiate - instantiate a dentry for inode
332 * Called with dcache_lock held.
333 */
334static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
335{
336 if (!inode)
337 return;
338
339 assert_spin_locked(&dcache_lock);
340
341 spin_lock(&dentry->d_lock);
342 __fsnotify_update_dcache_flags(dentry);
343 spin_unlock(&dentry->d_lock);
344}
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345
346/* called from fsnotify listeners, such as fanotify or dnotify */
347
90586523 348/* get a reference to an existing or create a new group */
0d2e2a1d 349extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops);
ffab8340 350/* drop reference on a group from fsnotify_alloc_group */
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351extern void fsnotify_put_group(struct fsnotify_group *group);
352
353/* take a reference to an event */
354extern void fsnotify_get_event(struct fsnotify_event *event);
355extern void fsnotify_put_event(struct fsnotify_event *event);
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356/* find private data previously attached to an event and unlink it */
357extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group,
358 struct fsnotify_event *event);
90586523 359
a2d8bc6c 360/* attach the event to the group notification queue */
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361extern struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group,
362 struct fsnotify_event *event,
363 struct fsnotify_event_private_data *priv,
364 struct fsnotify_event *(*merge)(struct list_head *,
365 struct fsnotify_event *));
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366/* true if the group notification queue is empty */
367extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group);
368/* return, but do not dequeue the first event on the notification queue */
369extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group);
e4aff117 370/* return AND dequeue the first event on the notification queue */
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371extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group);
372
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373/* functions used to manipulate the marks attached to inodes */
374
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375/* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */
376extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt);
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377/* run all marks associated with an inode and update inode->i_fsnotify_mask */
378extern void fsnotify_recalc_inode_mask(struct inode *inode);
841bdc10 379extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark));
3be25f49 380/* find (and take a reference) to a mark associated with group and inode */
5444e298 381extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode);
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382/* find (and take a reference) to a mark associated with group and vfsmount */
383extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt);
9e1c7432 384/* copy the values from old into new */
e61ce867 385extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old);
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386/* set the ignored_mask of a mark */
387extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask);
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388/* set the mask of a mark (might pin the object into memory */
389extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask);
3be25f49 390/* attach the mark to both the group and the inode */
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391extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group,
392 struct inode *inode, struct vfsmount *mnt, int allow_dups);
3be25f49 393/* given a mark, flag it to be freed when all references are dropped */
841bdc10 394extern void fsnotify_destroy_mark(struct fsnotify_mark *mark);
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395/* run all the marks in a group, and clear all of the vfsmount marks */
396extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
397/* run all the marks in a group, and clear all of the inode marks */
398extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
399/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
400extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
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401/* run all the marks in a group, and flag them to be freed */
402extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group);
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403extern void fsnotify_get_mark(struct fsnotify_mark *mark);
404extern void fsnotify_put_mark(struct fsnotify_mark *mark);
164bc619 405extern void fsnotify_unmount_inodes(struct list_head *list);
3be25f49 406
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407/* put here because inotify does some weird stuff when destroying watches */
408extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask,
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409 void *data, int data_is,
410 const unsigned char *name,
f44aebcc 411 u32 cookie, gfp_t gfp);
62ffe5df 412
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413/* fanotify likes to change events after they are on lists... */
414extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event);
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415extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder,
416 struct fsnotify_event *new_event);
b4e4e140 417
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418#else
419
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420static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
421 const unsigned char *name, u32 cookie)
422{
423 return 0;
424}
3be25f49 425
2069601b 426static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask)
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427{}
428
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429static inline void __fsnotify_inode_delete(struct inode *inode)
430{}
431
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432static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
433{}
434
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435static inline void __fsnotify_update_dcache_flags(struct dentry *dentry)
436{}
437
438static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode)
439{}
440
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441static inline u32 fsnotify_get_cookie(void)
442{
443 return 0;
444}
445
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446static inline void fsnotify_unmount_inodes(struct list_head *list)
447{}
448
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449#endif /* CONFIG_FSNOTIFY */
450
451#endif /* __KERNEL __ */
452
453#endif /* __LINUX_FSNOTIFY_BACKEND_H */