1 /* 2 * Filesystem access notification for Linux 3 * 4 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <[email protected]> 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 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 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 47 #define FS_EXCL_UNLINK 0x04000000 /* do not send events if object is unlinked */ 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 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 65 #define FS_MOVE (FS_MOVED_FROM | FS_MOVED_TO) 66 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 76 struct fsnotify_group; 77 struct fsnotify_event; 78 struct fsnotify_mark; 79 struct fsnotify_event_private_data; 80 81 /* 82 * Each group much define these ops. The fsnotify infrastructure will call 83 * these operations for each relevant group. 84 * 85 * should_send_event - given a group, inode, and mask this function determines 86 * if the group is interested in this event. 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 - 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. 92 */ 93 struct fsnotify_ops { 94 bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, 95 struct fsnotify_mark *inode_mark, 96 struct fsnotify_mark *vfsmount_mark, 97 __u32 mask, void *data, int data_type); 98 int (*handle_event)(struct fsnotify_group *group, 99 struct fsnotify_mark *inode_mark, 100 struct fsnotify_mark *vfsmount_mark, 101 struct fsnotify_event *event); 102 void (*free_group_priv)(struct fsnotify_group *group); 103 void (*freeing_mark)(struct fsnotify_mark *mark, struct fsnotify_group *group); 104 void (*free_event_priv)(struct fsnotify_event_private_data *priv); 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 */ 113 struct fsnotify_group { 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 */ 123 124 const struct fsnotify_ops *ops; /* how this group handles things */ 125 126 /* 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 */ 132 133 /* stores all fastpath marks assoc with this group so they can be cleaned on unregister */ 134 spinlock_t mark_lock; /* protect marks_list */ 135 atomic_t num_marks; /* 1 for each mark and 1 for not being 136 * past the point of no return when freeing 137 * a group */ 138 struct list_head marks_list; /* all inode marks for this group */ 139 140 /* groups can define private fields here or use the void *private */ 141 union { 142 void *private; 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; 151 #endif 152 #ifdef CONFIG_FANOTIFY 153 struct fanotify_group_private_data { 154 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 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; 159 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 160 int f_flags; 161 } fanotify_data; 162 #endif /* CONFIG_FANOTIFY */ 163 }; 164 }; 165 166 /* 167 * A single event can be queued in multiple group->notification_lists. 168 * 169 * each group->notification_list will point to an event_holder which in turns points 170 * to the actual event that needs to be sent to userspace. 171 * 172 * Seemed cheaper to create a refcnt'd event and a small holder for every group 173 * than create a different event for every group 174 * 175 */ 176 struct fsnotify_event_holder { 177 struct fsnotify_event *event; 178 struct list_head event_list; 179 }; 180 181 /* 182 * Inotify needs to tack data onto an event. This struct lets us later find the 183 * correct private data of the correct group. 184 */ 185 struct fsnotify_event_private_data { 186 struct fsnotify_group *group; 187 struct list_head event_list; 188 }; 189 190 /* 191 * all of the information about the original object we want to now send to 192 * a group. If you want to carry more info from the accessing task to the 193 * listener this structure is where you need to be adding fields. 194 */ 195 struct fsnotify_event { 196 /* 197 * If we create an event we are also likely going to need a holder 198 * to link to a group. So embed one holder in the event. Means only 199 * one allocation for the common case where we only have one group 200 */ 201 struct fsnotify_event_holder holder; 202 spinlock_t lock; /* protection for the associated event_holder and private_list */ 203 /* to_tell may ONLY be dereferenced during handle_event(). */ 204 struct inode *to_tell; /* either the inode the event happened to or its parent */ 205 /* 206 * depending on the event type we should have either a path or inode 207 * We hold a reference on path, but NOT on inode. Since we have the ref on 208 * the path, it may be dereferenced at any point during this object's 209 * lifetime. That reference is dropped when this object's refcnt hits 210 * 0. If this event contains an inode instead of a path, the inode may 211 * ONLY be used during handle_event(). 212 */ 213 union { 214 struct path path; 215 struct inode *inode; 216 }; 217 /* when calling fsnotify tell it if the data is a path or inode */ 218 #define FSNOTIFY_EVENT_NONE 0 219 #define FSNOTIFY_EVENT_PATH 1 220 #define FSNOTIFY_EVENT_INODE 2 221 int data_type; /* which of the above union we have */ 222 atomic_t refcnt; /* how many groups still are using/need to send this event */ 223 __u32 mask; /* the type of access, bitwise OR for FS_* event types */ 224 225 u32 sync_cookie; /* used to corrolate events, namely inotify mv events */ 226 const unsigned char *file_name; 227 size_t name_len; 228 struct pid *tgid; 229 230 #ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS 231 __u32 response; /* userspace answer to question */ 232 #endif /* CONFIG_FANOTIFY_ACCESS_PERMISSIONS */ 233 234 struct list_head private_data_list; /* groups can store private data here */ 235 }; 236 237 /* 238 * Inode specific fields in an fsnotify_mark 239 */ 240 struct fsnotify_inode_mark { 241 struct inode *inode; /* inode this mark is associated with */ 242 struct hlist_node i_list; /* list of marks by inode->i_fsnotify_marks */ 243 struct list_head free_i_list; /* tmp list used when freeing this mark */ 244 }; 245 246 /* 247 * Mount point specific fields in an fsnotify_mark 248 */ 249 struct fsnotify_vfsmount_mark { 250 struct vfsmount *mnt; /* vfsmount this mark is associated with */ 251 struct hlist_node m_list; /* list of marks by inode->i_fsnotify_marks */ 252 struct list_head free_m_list; /* tmp list used when freeing this mark */ 253 }; 254 255 /* 256 * a mark is simply an object attached to an in core inode which allows an 257 * fsnotify listener to indicate they are either no longer interested in events 258 * of a type matching mask or only interested in those events. 259 * 260 * these are flushed when an inode is evicted from core and may be flushed 261 * when the inode is modified (as seen by fsnotify_access). Some fsnotify users 262 * (such as dnotify) will flush these when the open fd is closed and not at 263 * inode eviction or modification. 264 */ 265 struct fsnotify_mark { 266 __u32 mask; /* mask this mark is for */ 267 /* we hold ref for each i_list and g_list. also one ref for each 'thing' 268 * in kernel that found and may be using this mark. */ 269 atomic_t refcnt; /* active things looking at this mark */ 270 struct fsnotify_group *group; /* group this mark is for */ 271 struct list_head g_list; /* list of marks by group->i_fsnotify_marks */ 272 spinlock_t lock; /* protect group and inode */ 273 union { 274 struct fsnotify_inode_mark i; 275 struct fsnotify_vfsmount_mark m; 276 }; 277 __u32 ignored_mask; /* events types to ignore */ 278 struct list_head free_g_list; /* tmp list used when freeing this mark */ 279 #define FSNOTIFY_MARK_FLAG_INODE 0x01 280 #define FSNOTIFY_MARK_FLAG_VFSMOUNT 0x02 281 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED 0x04 282 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY 0x08 283 #define FSNOTIFY_MARK_FLAG_ALIVE 0x10 284 unsigned int flags; /* vfsmount or inode mark? */ 285 struct list_head destroy_list; 286 void (*free_mark)(struct fsnotify_mark *mark); /* called on final put+free */ 287 }; 288 289 #ifdef CONFIG_FSNOTIFY 290 291 /* called from the vfs helpers */ 292 293 /* main fsnotify call to send events */ 294 extern int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 295 const unsigned char *name, u32 cookie); 296 extern void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask); 297 extern void __fsnotify_inode_delete(struct inode *inode); 298 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt); 299 extern u32 fsnotify_get_cookie(void); 300 301 static inline int fsnotify_inode_watches_children(struct inode *inode) 302 { 303 /* FS_EVENT_ON_CHILD is set if the inode may care */ 304 if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) 305 return 0; 306 /* this inode might care about child events, does it care about the 307 * specific set of events that can happen on a child? */ 308 return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; 309 } 310 311 /* 312 * Update the dentry with a flag indicating the interest of its parent to receive 313 * filesystem events when those events happens to this dentry->d_inode. 314 */ 315 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 316 { 317 struct dentry *parent; 318 319 assert_spin_locked(&dcache_lock); 320 assert_spin_locked(&dentry->d_lock); 321 322 parent = dentry->d_parent; 323 if (parent->d_inode && fsnotify_inode_watches_children(parent->d_inode)) 324 dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; 325 else 326 dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; 327 } 328 329 /* 330 * fsnotify_d_instantiate - instantiate a dentry for inode 331 * Called with dcache_lock held. 332 */ 333 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 334 { 335 if (!inode) 336 return; 337 338 assert_spin_locked(&dcache_lock); 339 340 spin_lock(&dentry->d_lock); 341 __fsnotify_update_dcache_flags(dentry); 342 spin_unlock(&dentry->d_lock); 343 } 344 345 /* called from fsnotify listeners, such as fanotify or dnotify */ 346 347 /* get a reference to an existing or create a new group */ 348 extern struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops); 349 /* drop reference on a group from fsnotify_alloc_group */ 350 extern void fsnotify_put_group(struct fsnotify_group *group); 351 352 /* take a reference to an event */ 353 extern void fsnotify_get_event(struct fsnotify_event *event); 354 extern void fsnotify_put_event(struct fsnotify_event *event); 355 /* find private data previously attached to an event and unlink it */ 356 extern struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, 357 struct fsnotify_event *event); 358 359 /* attach the event to the group notification queue */ 360 extern struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, 361 struct fsnotify_event *event, 362 struct fsnotify_event_private_data *priv, 363 struct fsnotify_event *(*merge)(struct list_head *, 364 struct fsnotify_event *)); 365 /* true if the group notification queue is empty */ 366 extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); 367 /* return, but do not dequeue the first event on the notification queue */ 368 extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); 369 /* return AND dequeue the first event on the notification queue */ 370 extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); 371 372 /* functions used to manipulate the marks attached to inodes */ 373 374 /* run all marks associated with a vfsmount and update mnt->mnt_fsnotify_mask */ 375 extern void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt); 376 /* run all marks associated with an inode and update inode->i_fsnotify_mask */ 377 extern void fsnotify_recalc_inode_mask(struct inode *inode); 378 extern void fsnotify_init_mark(struct fsnotify_mark *mark, void (*free_mark)(struct fsnotify_mark *mark)); 379 /* find (and take a reference) to a mark associated with group and inode */ 380 extern struct fsnotify_mark *fsnotify_find_inode_mark(struct fsnotify_group *group, struct inode *inode); 381 /* find (and take a reference) to a mark associated with group and vfsmount */ 382 extern struct fsnotify_mark *fsnotify_find_vfsmount_mark(struct fsnotify_group *group, struct vfsmount *mnt); 383 /* copy the values from old into new */ 384 extern void fsnotify_duplicate_mark(struct fsnotify_mark *new, struct fsnotify_mark *old); 385 /* set the ignored_mask of a mark */ 386 extern void fsnotify_set_mark_ignored_mask_locked(struct fsnotify_mark *mark, __u32 mask); 387 /* set the mask of a mark (might pin the object into memory */ 388 extern void fsnotify_set_mark_mask_locked(struct fsnotify_mark *mark, __u32 mask); 389 /* attach the mark to both the group and the inode */ 390 extern int fsnotify_add_mark(struct fsnotify_mark *mark, struct fsnotify_group *group, 391 struct inode *inode, struct vfsmount *mnt, int allow_dups); 392 /* given a mark, flag it to be freed when all references are dropped */ 393 extern void fsnotify_destroy_mark(struct fsnotify_mark *mark); 394 /* run all the marks in a group, and clear all of the vfsmount marks */ 395 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group); 396 /* run all the marks in a group, and clear all of the inode marks */ 397 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group); 398 /* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/ 399 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags); 400 /* run all the marks in a group, and flag them to be freed */ 401 extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); 402 extern void fsnotify_get_mark(struct fsnotify_mark *mark); 403 extern void fsnotify_put_mark(struct fsnotify_mark *mark); 404 extern void fsnotify_unmount_inodes(struct list_head *list); 405 406 /* put here because inotify does some weird stuff when destroying watches */ 407 extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, 408 void *data, int data_is, 409 const unsigned char *name, 410 u32 cookie, gfp_t gfp); 411 412 /* fanotify likes to change events after they are on lists... */ 413 extern struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event); 414 extern int fsnotify_replace_event(struct fsnotify_event_holder *old_holder, 415 struct fsnotify_event *new_event); 416 417 #else 418 419 static inline int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, 420 const unsigned char *name, u32 cookie) 421 { 422 return 0; 423 } 424 425 static inline void __fsnotify_parent(struct path *path, struct dentry *dentry, __u32 mask) 426 {} 427 428 static inline void __fsnotify_inode_delete(struct inode *inode) 429 {} 430 431 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 432 {} 433 434 static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) 435 {} 436 437 static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) 438 {} 439 440 static inline u32 fsnotify_get_cookie(void) 441 { 442 return 0; 443 } 444 445 static inline void fsnotify_unmount_inodes(struct list_head *list) 446 {} 447 448 #endif /* CONFIG_FSNOTIFY */ 449 450 #endif /* __KERNEL __ */ 451 452 #endif /* __LINUX_FSNOTIFY_BACKEND_H */ 453