2 * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2, or (at your option)
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; see the file COPYING. If not, write to
16 * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
20 * fsnotify inode mark locking/lifetime/and refcnting
23 * The group->recnt and mark->refcnt tell how many "things" in the kernel
24 * currently are referencing the objects. Both kind of objects typically will
25 * live inside the kernel with a refcnt of 2, one for its creation and one for
26 * the reference a group and a mark hold to each other.
27 * If you are holding the appropriate locks, you can take a reference and the
28 * object itself is guaranteed to survive until the reference is dropped.
31 * There are 3 locks involved with fsnotify inode marks and they MUST be taken
32 * in order as follows:
36 * mark->connector->lock
38 * group->mark_mutex protects the marks_list anchored inside a given group and
39 * each mark is hooked via the g_list. It also protects the groups private
40 * data (i.e group limits).
42 * mark->lock protects the marks attributes like its masks and flags.
43 * Furthermore it protects the access to a reference of the group that the mark
44 * is assigned to as well as the access to a reference of the inode/vfsmount
45 * that is being watched by the mark.
47 * mark->connector->lock protects the list of marks anchored inside an
48 * inode / vfsmount and each mark is hooked via the i_list.
50 * A list of notification marks relating to inode / mnt is contained in
51 * fsnotify_mark_connector. That structure is alive as long as there are any
52 * marks in the list and is also protected by fsnotify_mark_srcu. A mark gets
53 * detached from fsnotify_mark_connector when last reference to the mark is
54 * dropped. Thus having mark reference is enough to protect mark->connector
55 * pointer and to make sure fsnotify_mark_connector cannot disappear. Also
56 * because we remove mark from g_list before dropping mark reference associated
57 * with that, any mark found through g_list is guaranteed to have
58 * mark->connector set until we drop group->mark_mutex.
61 * Inode marks survive between when they are added to an inode and when their
62 * refcnt==0. Marks are also protected by fsnotify_mark_srcu.
64 * The inode mark can be cleared for a number of different reasons including:
65 * - The inode is unlinked for the last time. (fsnotify_inode_remove)
66 * - The inode is being evicted from cache. (fsnotify_inode_delete)
67 * - The fs the inode is on is unmounted. (fsnotify_inode_delete/fsnotify_unmount_inodes)
68 * - Something explicitly requests that it be removed. (fsnotify_destroy_mark)
69 * - The fsnotify_group associated with the mark is going away and all such marks
70 * need to be cleaned up. (fsnotify_clear_marks_by_group)
72 * This has the very interesting property of being able to run concurrently with
73 * any (or all) other directions.
77 #include <linux/init.h>
78 #include <linux/kernel.h>
79 #include <linux/kthread.h>
80 #include <linux/module.h>
81 #include <linux/mutex.h>
82 #include <linux/slab.h>
83 #include <linux/spinlock.h>
84 #include <linux/srcu.h>
86 #include <linux/atomic.h>
88 #include <linux/fsnotify_backend.h>
91 #define FSNOTIFY_REAPER_DELAY (1) /* 1 jiffy */
93 struct srcu_struct fsnotify_mark_srcu
;
94 struct kmem_cache
*fsnotify_mark_connector_cachep
;
96 static DEFINE_SPINLOCK(destroy_lock
);
97 static LIST_HEAD(destroy_list
);
98 static struct fsnotify_mark_connector
*connector_destroy_list
;
100 static void fsnotify_mark_destroy_workfn(struct work_struct
*work
);
101 static DECLARE_DELAYED_WORK(reaper_work
, fsnotify_mark_destroy_workfn
);
103 static void fsnotify_connector_destroy_workfn(struct work_struct
*work
);
104 static DECLARE_WORK(connector_reaper_work
, fsnotify_connector_destroy_workfn
);
106 void fsnotify_get_mark(struct fsnotify_mark
*mark
)
108 WARN_ON_ONCE(!refcount_read(&mark
->refcnt
));
109 refcount_inc(&mark
->refcnt
);
111 EXPORT_SYMBOL_GPL(fsnotify_put_mark
);
113 static void __fsnotify_recalc_mask(struct fsnotify_mark_connector
*conn
)
116 struct fsnotify_mark
*mark
;
118 assert_spin_locked(&conn
->lock
);
119 hlist_for_each_entry(mark
, &conn
->list
, obj_list
) {
120 if (mark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
)
121 new_mask
|= mark
->mask
;
123 if (conn
->flags
& FSNOTIFY_OBJ_TYPE_INODE
)
124 conn
->inode
->i_fsnotify_mask
= new_mask
;
125 else if (conn
->flags
& FSNOTIFY_OBJ_TYPE_VFSMOUNT
)
126 real_mount(conn
->mnt
)->mnt_fsnotify_mask
= new_mask
;
130 * Calculate mask of events for a list of marks. The caller must make sure
131 * connector and connector->inode cannot disappear under us. Callers achieve
132 * this by holding a mark->lock or mark->group->mark_mutex for a mark on this
135 void fsnotify_recalc_mask(struct fsnotify_mark_connector
*conn
)
140 spin_lock(&conn
->lock
);
141 __fsnotify_recalc_mask(conn
);
142 spin_unlock(&conn
->lock
);
143 if (conn
->flags
& FSNOTIFY_OBJ_TYPE_INODE
)
144 __fsnotify_update_child_dentry_flags(conn
->inode
);
147 /* Free all connectors queued for freeing once SRCU period ends */
148 static void fsnotify_connector_destroy_workfn(struct work_struct
*work
)
150 struct fsnotify_mark_connector
*conn
, *free
;
152 spin_lock(&destroy_lock
);
153 conn
= connector_destroy_list
;
154 connector_destroy_list
= NULL
;
155 spin_unlock(&destroy_lock
);
157 synchronize_srcu(&fsnotify_mark_srcu
);
160 conn
= conn
->destroy_next
;
161 kmem_cache_free(fsnotify_mark_connector_cachep
, free
);
165 static struct inode
*fsnotify_detach_connector_from_object(
166 struct fsnotify_mark_connector
*conn
)
168 struct inode
*inode
= NULL
;
170 if (conn
->flags
& FSNOTIFY_OBJ_TYPE_INODE
) {
172 rcu_assign_pointer(inode
->i_fsnotify_marks
, NULL
);
173 inode
->i_fsnotify_mask
= 0;
175 conn
->flags
&= ~FSNOTIFY_OBJ_TYPE_INODE
;
176 } else if (conn
->flags
& FSNOTIFY_OBJ_TYPE_VFSMOUNT
) {
177 rcu_assign_pointer(real_mount(conn
->mnt
)->mnt_fsnotify_marks
,
179 real_mount(conn
->mnt
)->mnt_fsnotify_mask
= 0;
181 conn
->flags
&= ~FSNOTIFY_OBJ_TYPE_VFSMOUNT
;
187 static void fsnotify_final_mark_destroy(struct fsnotify_mark
*mark
)
189 struct fsnotify_group
*group
= mark
->group
;
191 if (WARN_ON_ONCE(!group
))
193 group
->ops
->free_mark(mark
);
194 fsnotify_put_group(group
);
197 void fsnotify_put_mark(struct fsnotify_mark
*mark
)
199 struct fsnotify_mark_connector
*conn
;
200 struct inode
*inode
= NULL
;
201 bool free_conn
= false;
203 /* Catch marks that were actually never attached to object */
204 if (!mark
->connector
) {
205 if (refcount_dec_and_test(&mark
->refcnt
))
206 fsnotify_final_mark_destroy(mark
);
211 * We have to be careful so that traversals of obj_list under lock can
212 * safely grab mark reference.
214 if (!refcount_dec_and_lock(&mark
->refcnt
, &mark
->connector
->lock
))
217 conn
= mark
->connector
;
218 hlist_del_init_rcu(&mark
->obj_list
);
219 if (hlist_empty(&conn
->list
)) {
220 inode
= fsnotify_detach_connector_from_object(conn
);
223 __fsnotify_recalc_mask(conn
);
225 mark
->connector
= NULL
;
226 spin_unlock(&conn
->lock
);
231 spin_lock(&destroy_lock
);
232 conn
->destroy_next
= connector_destroy_list
;
233 connector_destroy_list
= conn
;
234 spin_unlock(&destroy_lock
);
235 queue_work(system_unbound_wq
, &connector_reaper_work
);
238 * Note that we didn't update flags telling whether inode cares about
239 * what's happening with children. We update these flags from
240 * __fsnotify_parent() lazily when next event happens on one of our
243 spin_lock(&destroy_lock
);
244 list_add(&mark
->g_list
, &destroy_list
);
245 spin_unlock(&destroy_lock
);
246 queue_delayed_work(system_unbound_wq
, &reaper_work
,
247 FSNOTIFY_REAPER_DELAY
);
251 * Get mark reference when we found the mark via lockless traversal of object
252 * list. Mark can be already removed from the list by now and on its way to be
253 * destroyed once SRCU period ends.
255 * Also pin the group so it doesn't disappear under us.
257 static bool fsnotify_get_mark_safe(struct fsnotify_mark
*mark
)
262 if (refcount_inc_not_zero(&mark
->refcnt
)) {
263 spin_lock(&mark
->lock
);
264 if (mark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
) {
265 /* mark is attached, group is still alive then */
266 atomic_inc(&mark
->group
->user_waits
);
267 spin_unlock(&mark
->lock
);
270 spin_unlock(&mark
->lock
);
271 fsnotify_put_mark(mark
);
277 * Puts marks and wakes up group destruction if necessary.
279 * Pairs with fsnotify_get_mark_safe()
281 static void fsnotify_put_mark_wake(struct fsnotify_mark
*mark
)
284 struct fsnotify_group
*group
= mark
->group
;
286 fsnotify_put_mark(mark
);
288 * We abuse notification_waitq on group shutdown for waiting for
289 * all marks pinned when waiting for userspace.
291 if (atomic_dec_and_test(&group
->user_waits
) && group
->shutdown
)
292 wake_up(&group
->notification_waitq
);
296 bool fsnotify_prepare_user_wait(struct fsnotify_iter_info
*iter_info
)
298 /* This can fail if mark is being removed */
299 if (!fsnotify_get_mark_safe(iter_info
->inode_mark
))
301 if (!fsnotify_get_mark_safe(iter_info
->vfsmount_mark
)) {
302 fsnotify_put_mark_wake(iter_info
->inode_mark
);
307 * Now that both marks are pinned by refcount in the inode / vfsmount
308 * lists, we can drop SRCU lock, and safely resume the list iteration
309 * once userspace returns.
311 srcu_read_unlock(&fsnotify_mark_srcu
, iter_info
->srcu_idx
);
316 void fsnotify_finish_user_wait(struct fsnotify_iter_info
*iter_info
)
318 iter_info
->srcu_idx
= srcu_read_lock(&fsnotify_mark_srcu
);
319 fsnotify_put_mark_wake(iter_info
->inode_mark
);
320 fsnotify_put_mark_wake(iter_info
->vfsmount_mark
);
324 * Mark mark as detached, remove it from group list. Mark still stays in object
325 * list until its last reference is dropped. Note that we rely on mark being
326 * removed from group list before corresponding reference to it is dropped. In
327 * particular we rely on mark->connector being valid while we hold
328 * group->mark_mutex if we found the mark through g_list.
330 * Must be called with group->mark_mutex held. The caller must either hold
331 * reference to the mark or be protected by fsnotify_mark_srcu.
333 void fsnotify_detach_mark(struct fsnotify_mark
*mark
)
335 struct fsnotify_group
*group
= mark
->group
;
337 WARN_ON_ONCE(!mutex_is_locked(&group
->mark_mutex
));
338 WARN_ON_ONCE(!srcu_read_lock_held(&fsnotify_mark_srcu
) &&
339 refcount_read(&mark
->refcnt
) < 1 +
340 !!(mark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
));
342 spin_lock(&mark
->lock
);
343 /* something else already called this function on this mark */
344 if (!(mark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
)) {
345 spin_unlock(&mark
->lock
);
348 mark
->flags
&= ~FSNOTIFY_MARK_FLAG_ATTACHED
;
349 list_del_init(&mark
->g_list
);
350 spin_unlock(&mark
->lock
);
352 atomic_dec(&group
->num_marks
);
354 /* Drop mark reference acquired in fsnotify_add_mark_locked() */
355 fsnotify_put_mark(mark
);
359 * Free fsnotify mark. The mark is actually only marked as being freed. The
360 * freeing is actually happening only once last reference to the mark is
361 * dropped from a workqueue which first waits for srcu period end.
363 * Caller must have a reference to the mark or be protected by
364 * fsnotify_mark_srcu.
366 void fsnotify_free_mark(struct fsnotify_mark
*mark
)
368 struct fsnotify_group
*group
= mark
->group
;
370 spin_lock(&mark
->lock
);
371 /* something else already called this function on this mark */
372 if (!(mark
->flags
& FSNOTIFY_MARK_FLAG_ALIVE
)) {
373 spin_unlock(&mark
->lock
);
376 mark
->flags
&= ~FSNOTIFY_MARK_FLAG_ALIVE
;
377 spin_unlock(&mark
->lock
);
380 * Some groups like to know that marks are being freed. This is a
381 * callback to the group function to let it know that this mark
384 if (group
->ops
->freeing_mark
)
385 group
->ops
->freeing_mark(mark
, group
);
388 void fsnotify_destroy_mark(struct fsnotify_mark
*mark
,
389 struct fsnotify_group
*group
)
391 mutex_lock_nested(&group
->mark_mutex
, SINGLE_DEPTH_NESTING
);
392 fsnotify_detach_mark(mark
);
393 mutex_unlock(&group
->mark_mutex
);
394 fsnotify_free_mark(mark
);
396 EXPORT_SYMBOL_GPL(fsnotify_destroy_mark
);
399 * Sorting function for lists of fsnotify marks.
401 * Fanotify supports different notification classes (reflected as priority of
402 * notification group). Events shall be passed to notification groups in
403 * decreasing priority order. To achieve this marks in notification lists for
404 * inodes and vfsmounts are sorted so that priorities of corresponding groups
407 * Furthermore correct handling of the ignore mask requires processing inode
408 * and vfsmount marks of each group together. Using the group address as
409 * further sort criterion provides a unique sorting order and thus we can
410 * merge inode and vfsmount lists of marks in linear time and find groups
411 * present in both lists.
413 * A return value of 1 signifies that b has priority over a.
414 * A return value of 0 signifies that the two marks have to be handled together.
415 * A return value of -1 signifies that a has priority over b.
417 int fsnotify_compare_groups(struct fsnotify_group
*a
, struct fsnotify_group
*b
)
425 if (a
->priority
< b
->priority
)
427 if (a
->priority
> b
->priority
)
434 static int fsnotify_attach_connector_to_object(
435 struct fsnotify_mark_connector __rcu
**connp
,
437 struct vfsmount
*mnt
)
439 struct fsnotify_mark_connector
*conn
;
441 conn
= kmem_cache_alloc(fsnotify_mark_connector_cachep
, GFP_KERNEL
);
444 spin_lock_init(&conn
->lock
);
445 INIT_HLIST_HEAD(&conn
->list
);
447 conn
->flags
= FSNOTIFY_OBJ_TYPE_INODE
;
448 conn
->inode
= igrab(inode
);
450 conn
->flags
= FSNOTIFY_OBJ_TYPE_VFSMOUNT
;
454 * cmpxchg() provides the barrier so that readers of *connp can see
455 * only initialized structure
457 if (cmpxchg(connp
, NULL
, conn
)) {
458 /* Someone else created list structure for us */
461 kmem_cache_free(fsnotify_mark_connector_cachep
, conn
);
468 * Get mark connector, make sure it is alive and return with its lock held.
469 * This is for users that get connector pointer from inode or mount. Users that
470 * hold reference to a mark on the list may directly lock connector->lock as
471 * they are sure list cannot go away under them.
473 static struct fsnotify_mark_connector
*fsnotify_grab_connector(
474 struct fsnotify_mark_connector __rcu
**connp
)
476 struct fsnotify_mark_connector
*conn
;
479 idx
= srcu_read_lock(&fsnotify_mark_srcu
);
480 conn
= srcu_dereference(*connp
, &fsnotify_mark_srcu
);
483 spin_lock(&conn
->lock
);
484 if (!(conn
->flags
& (FSNOTIFY_OBJ_TYPE_INODE
|
485 FSNOTIFY_OBJ_TYPE_VFSMOUNT
))) {
486 spin_unlock(&conn
->lock
);
487 srcu_read_unlock(&fsnotify_mark_srcu
, idx
);
491 srcu_read_unlock(&fsnotify_mark_srcu
, idx
);
496 * Add mark into proper place in given list of marks. These marks may be used
497 * for the fsnotify backend to determine which event types should be delivered
498 * to which group and for which inodes. These marks are ordered according to
499 * priority, highest number first, and then by the group's location in memory.
501 static int fsnotify_add_mark_list(struct fsnotify_mark
*mark
,
502 struct inode
*inode
, struct vfsmount
*mnt
,
505 struct fsnotify_mark
*lmark
, *last
= NULL
;
506 struct fsnotify_mark_connector
*conn
;
507 struct fsnotify_mark_connector __rcu
**connp
;
511 if (WARN_ON(!inode
&& !mnt
))
514 connp
= &inode
->i_fsnotify_marks
;
516 connp
= &real_mount(mnt
)->mnt_fsnotify_marks
;
518 spin_lock(&mark
->lock
);
519 conn
= fsnotify_grab_connector(connp
);
521 spin_unlock(&mark
->lock
);
522 err
= fsnotify_attach_connector_to_object(connp
, inode
, mnt
);
528 /* is mark the first mark? */
529 if (hlist_empty(&conn
->list
)) {
530 hlist_add_head_rcu(&mark
->obj_list
, &conn
->list
);
534 /* should mark be in the middle of the current list? */
535 hlist_for_each_entry(lmark
, &conn
->list
, obj_list
) {
538 if ((lmark
->group
== mark
->group
) &&
539 (lmark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
) &&
545 cmp
= fsnotify_compare_groups(lmark
->group
, mark
->group
);
547 hlist_add_before_rcu(&mark
->obj_list
, &lmark
->obj_list
);
552 BUG_ON(last
== NULL
);
553 /* mark should be the last entry. last is the current last entry */
554 hlist_add_behind_rcu(&mark
->obj_list
, &last
->obj_list
);
556 mark
->connector
= conn
;
558 spin_unlock(&conn
->lock
);
559 spin_unlock(&mark
->lock
);
564 * Attach an initialized mark to a given group and fs object.
565 * These marks may be used for the fsnotify backend to determine which
566 * event types should be delivered to which group.
568 int fsnotify_add_mark_locked(struct fsnotify_mark
*mark
, struct inode
*inode
,
569 struct vfsmount
*mnt
, int allow_dups
)
571 struct fsnotify_group
*group
= mark
->group
;
574 BUG_ON(inode
&& mnt
);
575 BUG_ON(!inode
&& !mnt
);
576 BUG_ON(!mutex_is_locked(&group
->mark_mutex
));
582 * mark->connector->lock
584 spin_lock(&mark
->lock
);
585 mark
->flags
|= FSNOTIFY_MARK_FLAG_ALIVE
| FSNOTIFY_MARK_FLAG_ATTACHED
;
587 list_add(&mark
->g_list
, &group
->marks_list
);
588 atomic_inc(&group
->num_marks
);
589 fsnotify_get_mark(mark
); /* for g_list */
590 spin_unlock(&mark
->lock
);
592 ret
= fsnotify_add_mark_list(mark
, inode
, mnt
, allow_dups
);
597 fsnotify_recalc_mask(mark
->connector
);
601 spin_lock(&mark
->lock
);
602 mark
->flags
&= ~(FSNOTIFY_MARK_FLAG_ALIVE
|
603 FSNOTIFY_MARK_FLAG_ATTACHED
);
604 list_del_init(&mark
->g_list
);
605 spin_unlock(&mark
->lock
);
606 atomic_dec(&group
->num_marks
);
608 fsnotify_put_mark(mark
);
611 EXPORT_SYMBOL_GPL(fsnotify_add_mark
);
613 int fsnotify_add_mark(struct fsnotify_mark
*mark
, struct inode
*inode
,
614 struct vfsmount
*mnt
, int allow_dups
)
617 struct fsnotify_group
*group
= mark
->group
;
619 mutex_lock(&group
->mark_mutex
);
620 ret
= fsnotify_add_mark_locked(mark
, inode
, mnt
, allow_dups
);
621 mutex_unlock(&group
->mark_mutex
);
626 * Given a list of marks, find the mark associated with given group. If found
627 * take a reference to that mark and return it, else return NULL.
629 struct fsnotify_mark
*fsnotify_find_mark(
630 struct fsnotify_mark_connector __rcu
**connp
,
631 struct fsnotify_group
*group
)
633 struct fsnotify_mark_connector
*conn
;
634 struct fsnotify_mark
*mark
;
636 conn
= fsnotify_grab_connector(connp
);
640 hlist_for_each_entry(mark
, &conn
->list
, obj_list
) {
641 if (mark
->group
== group
&&
642 (mark
->flags
& FSNOTIFY_MARK_FLAG_ATTACHED
)) {
643 fsnotify_get_mark(mark
);
644 spin_unlock(&conn
->lock
);
648 spin_unlock(&conn
->lock
);
652 /* Clear any marks in a group with given type */
653 void fsnotify_clear_marks_by_group(struct fsnotify_group
*group
,
656 struct fsnotify_mark
*lmark
, *mark
;
658 struct list_head
*head
= &to_free
;
660 /* Skip selection step if we want to clear all marks. */
661 if (type
== FSNOTIFY_OBJ_ALL_TYPES
) {
662 head
= &group
->marks_list
;
666 * We have to be really careful here. Anytime we drop mark_mutex, e.g.
667 * fsnotify_clear_marks_by_inode() can come and free marks. Even in our
668 * to_free list so we have to use mark_mutex even when accessing that
669 * list. And freeing mark requires us to drop mark_mutex. So we can
670 * reliably free only the first mark in the list. That's why we first
671 * move marks to free to to_free list in one go and then free marks in
672 * to_free list one by one.
674 mutex_lock_nested(&group
->mark_mutex
, SINGLE_DEPTH_NESTING
);
675 list_for_each_entry_safe(mark
, lmark
, &group
->marks_list
, g_list
) {
676 if (mark
->connector
->flags
& type
)
677 list_move(&mark
->g_list
, &to_free
);
679 mutex_unlock(&group
->mark_mutex
);
683 mutex_lock_nested(&group
->mark_mutex
, SINGLE_DEPTH_NESTING
);
684 if (list_empty(head
)) {
685 mutex_unlock(&group
->mark_mutex
);
688 mark
= list_first_entry(head
, struct fsnotify_mark
, g_list
);
689 fsnotify_get_mark(mark
);
690 fsnotify_detach_mark(mark
);
691 mutex_unlock(&group
->mark_mutex
);
692 fsnotify_free_mark(mark
);
693 fsnotify_put_mark(mark
);
697 /* Destroy all marks attached to inode / vfsmount */
698 void fsnotify_destroy_marks(struct fsnotify_mark_connector __rcu
**connp
)
700 struct fsnotify_mark_connector
*conn
;
701 struct fsnotify_mark
*mark
, *old_mark
= NULL
;
704 conn
= fsnotify_grab_connector(connp
);
708 * We have to be careful since we can race with e.g.
709 * fsnotify_clear_marks_by_group() and once we drop the conn->lock, the
710 * list can get modified. However we are holding mark reference and
711 * thus our mark cannot be removed from obj_list so we can continue
712 * iteration after regaining conn->lock.
714 hlist_for_each_entry(mark
, &conn
->list
, obj_list
) {
715 fsnotify_get_mark(mark
);
716 spin_unlock(&conn
->lock
);
718 fsnotify_put_mark(old_mark
);
720 fsnotify_destroy_mark(mark
, mark
->group
);
721 spin_lock(&conn
->lock
);
724 * Detach list from object now so that we don't pin inode until all
725 * mark references get dropped. It would lead to strange results such
726 * as delaying inode deletion or blocking unmount.
728 inode
= fsnotify_detach_connector_from_object(conn
);
729 spin_unlock(&conn
->lock
);
731 fsnotify_put_mark(old_mark
);
736 * Nothing fancy, just initialize lists and locks and counters.
738 void fsnotify_init_mark(struct fsnotify_mark
*mark
,
739 struct fsnotify_group
*group
)
741 memset(mark
, 0, sizeof(*mark
));
742 spin_lock_init(&mark
->lock
);
743 refcount_set(&mark
->refcnt
, 1);
744 fsnotify_get_group(group
);
747 EXPORT_SYMBOL_GPL(fsnotify_init_mark
);
750 * Destroy all marks in destroy_list, waits for SRCU period to finish before
751 * actually freeing marks.
753 static void fsnotify_mark_destroy_workfn(struct work_struct
*work
)
755 struct fsnotify_mark
*mark
, *next
;
756 struct list_head private_destroy_list
;
758 spin_lock(&destroy_lock
);
759 /* exchange the list head */
760 list_replace_init(&destroy_list
, &private_destroy_list
);
761 spin_unlock(&destroy_lock
);
763 synchronize_srcu(&fsnotify_mark_srcu
);
765 list_for_each_entry_safe(mark
, next
, &private_destroy_list
, g_list
) {
766 list_del_init(&mark
->g_list
);
767 fsnotify_final_mark_destroy(mark
);
771 /* Wait for all marks queued for destruction to be actually destroyed */
772 void fsnotify_wait_marks_destroyed(void)
774 flush_delayed_work(&reaper_work
);