Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 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/fs.h> /* struct inode */ |
| 13 | #include <linux/list.h> |
| 14 | #include <linux/path.h> /* struct path */ |
| 15 | #include <linux/spinlock.h> |
| 16 | #include <linux/types.h> |
| 17 | |
| 18 | #include <asm/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_IN_ISDIR 0x40000000 /* event occurred against dir */ |
| 44 | #define FS_IN_ONESHOT 0x80000000 /* only send event once */ |
| 45 | |
| 46 | #define FS_DN_RENAME 0x10000000 /* file renamed */ |
| 47 | #define FS_DN_MULTISHOT 0x20000000 /* dnotify multishot */ |
| 48 | |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 49 | /* This inode cares about things that happen to its children. Always set for |
| 50 | * dnotify and inotify. */ |
| 51 | #define FS_EVENT_ON_CHILD 0x08000000 |
| 52 | |
| 53 | /* This is a list of all events that may get sent to a parernt based on fs event |
| 54 | * happening to inodes inside that directory */ |
| 55 | #define FS_EVENTS_POSS_ON_CHILD (FS_ACCESS | FS_MODIFY | FS_ATTRIB |\ |
| 56 | FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\ |
| 57 | FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\ |
| 58 | FS_DELETE) |
| 59 | |
Eric Paris | 3c5119c | 2009-05-21 17:01:33 -0400 | [diff] [blame] | 60 | /* listeners that hard code group numbers near the top */ |
| 61 | #define DNOTIFY_GROUP_NUM UINT_MAX |
| 62 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 63 | struct fsnotify_group; |
| 64 | struct fsnotify_event; |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 65 | struct fsnotify_mark_entry; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 66 | |
| 67 | /* |
| 68 | * Each group much define these ops. The fsnotify infrastructure will call |
| 69 | * these operations for each relevant group. |
| 70 | * |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 71 | * should_send_event - given a group, inode, and mask this function determines |
| 72 | * if the group is interested in this event. |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 73 | * handle_event - main call for a group to handle an fs event |
| 74 | * free_group_priv - called when a group refcnt hits 0 to clean up the private union |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 75 | * freeing-mark - this means that a mark has been flagged to die when everything |
| 76 | * finishes using it. The function is supplied with what must be a |
| 77 | * valid group and inode to use to clean up. |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 78 | */ |
| 79 | struct fsnotify_ops { |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 80 | bool (*should_send_event)(struct fsnotify_group *group, struct inode *inode, __u32 mask); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 81 | int (*handle_event)(struct fsnotify_group *group, struct fsnotify_event *event); |
| 82 | void (*free_group_priv)(struct fsnotify_group *group); |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 83 | void (*freeing_mark)(struct fsnotify_mark_entry *entry, struct fsnotify_group *group); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 84 | }; |
| 85 | |
| 86 | /* |
| 87 | * A group is a "thing" that wants to receive notification about filesystem |
| 88 | * events. The mask holds the subset of event types this group cares about. |
| 89 | * refcnt on a group is up to the implementor and at any moment if it goes 0 |
| 90 | * everything will be cleaned up. |
| 91 | */ |
| 92 | struct fsnotify_group { |
| 93 | /* |
| 94 | * global list of all groups receiving events from fsnotify. |
| 95 | * anchored by fsnotify_groups and protected by either fsnotify_grp_mutex |
| 96 | * or fsnotify_grp_srcu depending on write vs read. |
| 97 | */ |
| 98 | struct list_head group_list; |
| 99 | |
| 100 | /* |
| 101 | * Defines all of the event types in which this group is interested. |
| 102 | * This mask is a bitwise OR of the FS_* events from above. Each time |
| 103 | * this mask changes for a group (if it changes) the correct functions |
| 104 | * must be called to update the global structures which indicate global |
| 105 | * interest in event types. |
| 106 | */ |
| 107 | __u32 mask; |
| 108 | |
| 109 | /* |
| 110 | * How the refcnt is used is up to each group. When the refcnt hits 0 |
| 111 | * fsnotify will clean up all of the resources associated with this group. |
| 112 | * As an example, the dnotify group will always have a refcnt=1 and that |
| 113 | * will never change. Inotify, on the other hand, has a group per |
| 114 | * inotify_init() and the refcnt will hit 0 only when that fd has been |
| 115 | * closed. |
| 116 | */ |
| 117 | atomic_t refcnt; /* things with interest in this group */ |
| 118 | unsigned int group_num; /* simply prevents accidental group collision */ |
| 119 | |
| 120 | const struct fsnotify_ops *ops; /* how this group handles things */ |
| 121 | |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 122 | /* needed to send notification to userspace */ |
| 123 | struct mutex notification_mutex; /* protect the notification_list */ |
| 124 | struct list_head notification_list; /* list of event_holder this group needs to send to userspace */ |
| 125 | wait_queue_head_t notification_waitq; /* read() on the notification file blocks on this waitq */ |
| 126 | unsigned int q_len; /* events on the queue */ |
| 127 | unsigned int max_events; /* maximum events allowed on the list */ |
| 128 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 129 | /* stores all fastapth entries assoc with this group so they can be cleaned on unregister */ |
| 130 | spinlock_t mark_lock; /* protect mark_entries list */ |
| 131 | atomic_t num_marks; /* 1 for each mark entry and 1 for not being |
| 132 | * past the point of no return when freeing |
| 133 | * a group */ |
| 134 | struct list_head mark_entries; /* all inode mark entries for this group */ |
| 135 | |
| 136 | /* prevents double list_del of group_list. protected by global fsnotify_grp_mutex */ |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 137 | bool on_group_list; |
| 138 | |
| 139 | /* groups can define private fields here or use the void *private */ |
| 140 | union { |
| 141 | void *private; |
| 142 | }; |
| 143 | }; |
| 144 | |
| 145 | /* |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 146 | * A single event can be queued in multiple group->notification_lists. |
| 147 | * |
| 148 | * each group->notification_list will point to an event_holder which in turns points |
| 149 | * to the actual event that needs to be sent to userspace. |
| 150 | * |
| 151 | * Seemed cheaper to create a refcnt'd event and a small holder for every group |
| 152 | * than create a different event for every group |
| 153 | * |
| 154 | */ |
| 155 | struct fsnotify_event_holder { |
| 156 | struct fsnotify_event *event; |
| 157 | struct list_head event_list; |
| 158 | }; |
| 159 | |
| 160 | /* |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 161 | * all of the information about the original object we want to now send to |
| 162 | * a group. If you want to carry more info from the accessing task to the |
| 163 | * listener this structure is where you need to be adding fields. |
| 164 | */ |
| 165 | struct fsnotify_event { |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 166 | /* |
| 167 | * If we create an event we are also likely going to need a holder |
| 168 | * to link to a group. So embed one holder in the event. Means only |
| 169 | * one allocation for the common case where we only have one group |
| 170 | */ |
| 171 | struct fsnotify_event_holder holder; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 172 | spinlock_t lock; /* protection for the associated event_holder and private_list */ |
| 173 | /* to_tell may ONLY be dereferenced during handle_event(). */ |
| 174 | struct inode *to_tell; /* either the inode the event happened to or its parent */ |
| 175 | /* |
| 176 | * depending on the event type we should have either a path or inode |
| 177 | * We hold a reference on path, but NOT on inode. Since we have the ref on |
| 178 | * the path, it may be dereferenced at any point during this object's |
| 179 | * lifetime. That reference is dropped when this object's refcnt hits |
| 180 | * 0. If this event contains an inode instead of a path, the inode may |
| 181 | * ONLY be used during handle_event(). |
| 182 | */ |
| 183 | union { |
| 184 | struct path path; |
| 185 | struct inode *inode; |
| 186 | }; |
| 187 | /* when calling fsnotify tell it if the data is a path or inode */ |
| 188 | #define FSNOTIFY_EVENT_NONE 0 |
| 189 | #define FSNOTIFY_EVENT_PATH 1 |
| 190 | #define FSNOTIFY_EVENT_INODE 2 |
| 191 | #define FSNOTIFY_EVENT_FILE 3 |
| 192 | int data_type; /* which of the above union we have */ |
| 193 | atomic_t refcnt; /* how many groups still are using/need to send this event */ |
| 194 | __u32 mask; /* the type of access, bitwise OR for FS_* event types */ |
Eric Paris | 62ffe5d | 2009-05-21 17:01:43 -0400 | [diff] [blame^] | 195 | |
| 196 | char *file_name; |
| 197 | size_t name_len; |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 198 | }; |
| 199 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 200 | /* |
| 201 | * a mark is simply an entry attached to an in core inode which allows an |
| 202 | * fsnotify listener to indicate they are either no longer interested in events |
| 203 | * of a type matching mask or only interested in those events. |
| 204 | * |
| 205 | * these are flushed when an inode is evicted from core and may be flushed |
| 206 | * when the inode is modified (as seen by fsnotify_access). Some fsnotify users |
| 207 | * (such as dnotify) will flush these when the open fd is closed and not at |
| 208 | * inode eviction or modification. |
| 209 | */ |
| 210 | struct fsnotify_mark_entry { |
| 211 | __u32 mask; /* mask this mark entry is for */ |
| 212 | /* we hold ref for each i_list and g_list. also one ref for each 'thing' |
| 213 | * in kernel that found and may be using this mark. */ |
| 214 | atomic_t refcnt; /* active things looking at this mark */ |
| 215 | struct inode *inode; /* inode this entry is associated with */ |
| 216 | struct fsnotify_group *group; /* group this mark entry is for */ |
| 217 | struct hlist_node i_list; /* list of mark_entries by inode->i_fsnotify_mark_entries */ |
| 218 | struct list_head g_list; /* list of mark_entries by group->i_fsnotify_mark_entries */ |
| 219 | spinlock_t lock; /* protect group, inode, and killme */ |
| 220 | struct list_head free_i_list; /* tmp list used when freeing this mark */ |
| 221 | struct list_head free_g_list; /* tmp list used when freeing this mark */ |
| 222 | void (*free_mark)(struct fsnotify_mark_entry *entry); /* called on final put+free */ |
| 223 | }; |
| 224 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 225 | #ifdef CONFIG_FSNOTIFY |
| 226 | |
| 227 | /* called from the vfs helpers */ |
| 228 | |
| 229 | /* main fsnotify call to send events */ |
Eric Paris | 62ffe5d | 2009-05-21 17:01:43 -0400 | [diff] [blame^] | 230 | extern void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, const char *name); |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 231 | extern void __fsnotify_parent(struct dentry *dentry, __u32 mask); |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 232 | extern void __fsnotify_inode_delete(struct inode *inode); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 233 | |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 234 | static inline int fsnotify_inode_watches_children(struct inode *inode) |
| 235 | { |
| 236 | /* FS_EVENT_ON_CHILD is set if the inode may care */ |
| 237 | if (!(inode->i_fsnotify_mask & FS_EVENT_ON_CHILD)) |
| 238 | return 0; |
| 239 | /* this inode might care about child events, does it care about the |
| 240 | * specific set of events that can happen on a child? */ |
| 241 | return inode->i_fsnotify_mask & FS_EVENTS_POSS_ON_CHILD; |
| 242 | } |
| 243 | |
| 244 | /* |
| 245 | * Update the dentry with a flag indicating the interest of its parent to receive |
| 246 | * filesystem events when those events happens to this dentry->d_inode. |
| 247 | */ |
| 248 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) |
| 249 | { |
| 250 | struct dentry *parent; |
| 251 | |
| 252 | assert_spin_locked(&dcache_lock); |
| 253 | assert_spin_locked(&dentry->d_lock); |
| 254 | |
| 255 | parent = dentry->d_parent; |
| 256 | if (fsnotify_inode_watches_children(parent->d_inode)) |
| 257 | dentry->d_flags |= DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 258 | else |
| 259 | dentry->d_flags &= ~DCACHE_FSNOTIFY_PARENT_WATCHED; |
| 260 | } |
| 261 | |
| 262 | /* |
| 263 | * fsnotify_d_instantiate - instantiate a dentry for inode |
| 264 | * Called with dcache_lock held. |
| 265 | */ |
| 266 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) |
| 267 | { |
| 268 | if (!inode) |
| 269 | return; |
| 270 | |
| 271 | assert_spin_locked(&dcache_lock); |
| 272 | |
| 273 | spin_lock(&dentry->d_lock); |
| 274 | __fsnotify_update_dcache_flags(dentry); |
| 275 | spin_unlock(&dentry->d_lock); |
| 276 | } |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 277 | |
| 278 | /* called from fsnotify listeners, such as fanotify or dnotify */ |
| 279 | |
| 280 | /* must call when a group changes its ->mask */ |
| 281 | extern void fsnotify_recalc_global_mask(void); |
| 282 | /* get a reference to an existing or create a new group */ |
| 283 | extern struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, |
| 284 | __u32 mask, |
| 285 | const struct fsnotify_ops *ops); |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 286 | /* run all marks associated with this group and update group->mask */ |
| 287 | extern void fsnotify_recalc_group_mask(struct fsnotify_group *group); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 288 | /* drop reference on a group from fsnotify_obtain_group */ |
| 289 | extern void fsnotify_put_group(struct fsnotify_group *group); |
| 290 | |
| 291 | /* take a reference to an event */ |
| 292 | extern void fsnotify_get_event(struct fsnotify_event *event); |
| 293 | extern void fsnotify_put_event(struct fsnotify_event *event); |
| 294 | /* find private data previously attached to an event */ |
| 295 | extern struct fsnotify_event_private_data *fsnotify_get_priv_from_event(struct fsnotify_group *group, |
| 296 | struct fsnotify_event *event); |
| 297 | |
Eric Paris | a2d8bc6 | 2009-05-21 17:01:37 -0400 | [diff] [blame] | 298 | /* attach the event to the group notification queue */ |
| 299 | extern int fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event); |
| 300 | /* true if the group notification queue is empty */ |
| 301 | extern bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group); |
| 302 | /* return, but do not dequeue the first event on the notification queue */ |
| 303 | extern struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group); |
| 304 | /* reutnr AND dequeue the first event on the notification queue */ |
| 305 | extern struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group); |
| 306 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 307 | /* functions used to manipulate the marks attached to inodes */ |
| 308 | |
| 309 | /* run all marks associated with an inode and update inode->i_fsnotify_mask */ |
| 310 | extern void fsnotify_recalc_inode_mask(struct inode *inode); |
| 311 | extern void fsnotify_init_mark(struct fsnotify_mark_entry *entry, void (*free_mark)(struct fsnotify_mark_entry *entry)); |
| 312 | /* find (and take a reference) to a mark associated with group and inode */ |
| 313 | extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_group *group, struct inode *inode); |
| 314 | /* attach the mark to both the group and the inode */ |
| 315 | extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode); |
| 316 | /* given a mark, flag it to be freed when all references are dropped */ |
| 317 | extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry); |
| 318 | /* run all the marks in a group, and flag them to be freed */ |
| 319 | extern void fsnotify_clear_marks_by_group(struct fsnotify_group *group); |
| 320 | extern void fsnotify_get_mark(struct fsnotify_mark_entry *entry); |
| 321 | extern void fsnotify_put_mark(struct fsnotify_mark_entry *entry); |
| 322 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 323 | /* put here because inotify does some weird stuff when destroying watches */ |
| 324 | extern struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, |
Eric Paris | 62ffe5d | 2009-05-21 17:01:43 -0400 | [diff] [blame^] | 325 | void *data, int data_is, const char *name); |
| 326 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 327 | #else |
| 328 | |
Eric Paris | 62ffe5d | 2009-05-21 17:01:43 -0400 | [diff] [blame^] | 329 | static inline void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is, |
| 330 | const char *name); |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 331 | {} |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 332 | |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 333 | static inline void __fsnotify_parent(struct dentry *dentry, __u32 mask) |
| 334 | {} |
| 335 | |
Eric Paris | 3be25f4 | 2009-05-21 17:01:26 -0400 | [diff] [blame] | 336 | static inline void __fsnotify_inode_delete(struct inode *inode) |
| 337 | {} |
| 338 | |
Eric Paris | c28f7e5 | 2009-05-21 17:01:29 -0400 | [diff] [blame] | 339 | static inline void __fsnotify_update_dcache_flags(struct dentry *dentry) |
| 340 | {} |
| 341 | |
| 342 | static inline void __fsnotify_d_instantiate(struct dentry *dentry, struct inode *inode) |
| 343 | {} |
| 344 | |
Eric Paris | 9058652 | 2009-05-21 17:01:20 -0400 | [diff] [blame] | 345 | #endif /* CONFIG_FSNOTIFY */ |
| 346 | |
| 347 | #endif /* __KERNEL __ */ |
| 348 | |
| 349 | #endif /* __LINUX_FSNOTIFY_BACKEND_H */ |