#include <asm/atomic.h>
-/* protects writes to fsnotify_groups and fsnotify_mask */
-static DEFINE_MUTEX(fsnotify_grp_mutex);
-/* protects reads while running the fsnotify_groups list */
-struct srcu_struct fsnotify_grp_srcu;
-/* all groups registered to receive filesystem notifications */
-LIST_HEAD(fsnotify_groups);
-/* bitwise OR of all events (FS_*) interesting to some group on this system */
-__u32 fsnotify_mask;
-
-/*
- * When a new group registers or changes it's set of interesting events
- * this function updates the fsnotify_mask to contain all interesting events
- */
-void fsnotify_recalc_global_mask(void)
-{
- struct fsnotify_group *group;
- __u32 mask = 0;
- int idx;
-
- idx = srcu_read_lock(&fsnotify_grp_srcu);
- list_for_each_entry_rcu(group, &fsnotify_groups, group_list)
- mask |= group->mask;
- srcu_read_unlock(&fsnotify_grp_srcu, idx);
- fsnotify_mask = mask;
-}
-
-/*
- * Update the group->mask by running all of the marks associated with this
- * group and finding the bitwise | of all of the mark->mask. If we change
- * the group->mask we need to update the global mask of events interesting
- * to the system.
- */
-void fsnotify_recalc_group_mask(struct fsnotify_group *group)
-{
- __u32 mask = 0;
- __u32 old_mask = group->mask;
- struct fsnotify_mark_entry *entry;
-
- spin_lock(&group->mark_lock);
- list_for_each_entry(entry, &group->mark_entries, g_list)
- mask |= entry->mask;
- spin_unlock(&group->mark_lock);
-
- group->mask = mask;
-
- if (old_mask != mask)
- fsnotify_recalc_global_mask();
-}
-
-/*
- * Take a reference to a group so things found under the fsnotify_grp_mutex
- * can't get freed under us
- */
-static void fsnotify_get_group(struct fsnotify_group *group)
-{
- atomic_inc(&group->refcnt);
-}
-
/*
* Final freeing of a group
*/
*/
static void fsnotify_destroy_group(struct fsnotify_group *group)
{
- /* clear all inode mark entries for this group */
+ /* clear all inode marks for this group */
fsnotify_clear_marks_by_group(group);
+ synchronize_srcu(&fsnotify_mark_srcu);
+
/* past the point of no return, matches the initial value of 1 */
if (atomic_dec_and_test(&group->num_marks))
fsnotify_final_destroy_group(group);
}
-/*
- * Remove this group from the global list of groups that will get events
- * this can be done even if there are still references and things still using
- * this group. This just stops the group from getting new events.
- */
-static void __fsnotify_evict_group(struct fsnotify_group *group)
-{
- BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
-
- if (group->on_group_list)
- list_del_rcu(&group->group_list);
- group->on_group_list = 0;
-}
-
-/*
- * Called when a group is no longer interested in getting events. This can be
- * used if a group is misbehaving or if for some reason a group should no longer
- * get any filesystem events.
- */
-void fsnotify_evict_group(struct fsnotify_group *group)
-{
- mutex_lock(&fsnotify_grp_mutex);
- __fsnotify_evict_group(group);
- mutex_unlock(&fsnotify_grp_mutex);
-}
-
/*
* Drop a reference to a group. Free it if it's through.
*/
void fsnotify_put_group(struct fsnotify_group *group)
{
- if (!atomic_dec_and_mutex_lock(&group->refcnt, &fsnotify_grp_mutex))
- return;
-
- /*
- * OK, now we know that there's no other users *and* we hold mutex,
- * so no new references will appear
- */
- __fsnotify_evict_group(group);
-
- /*
- * now it's off the list, so the only thing we might care about is
- * srcu access....
- */
- mutex_unlock(&fsnotify_grp_mutex);
- synchronize_srcu(&fsnotify_grp_srcu);
-
- /* and now it is really dead. _Nothing_ could be seeing it */
- fsnotify_recalc_global_mask();
- fsnotify_destroy_group(group);
-}
-
-/*
- * Simply run the fsnotify_groups list and find a group which matches
- * the given parameters. If a group is found we take a reference to that
- * group.
- */
-static struct fsnotify_group *fsnotify_find_group(unsigned int group_num, __u32 mask,
- const struct fsnotify_ops *ops)
-{
- struct fsnotify_group *group_iter;
- struct fsnotify_group *group = NULL;
-
- BUG_ON(!mutex_is_locked(&fsnotify_grp_mutex));
-
- list_for_each_entry_rcu(group_iter, &fsnotify_groups, group_list) {
- if (group_iter->group_num == group_num) {
- if ((group_iter->mask == mask) &&
- (group_iter->ops == ops)) {
- fsnotify_get_group(group_iter);
- group = group_iter;
- } else
- group = ERR_PTR(-EEXIST);
- }
- }
- return group;
+ if (atomic_dec_and_test(&group->refcnt))
+ fsnotify_destroy_group(group);
}
/*
- * Either finds an existing group which matches the group_num, mask, and ops or
- * creates a new group and adds it to the global group list. In either case we
- * take a reference for the group returned.
+ * Create a new fsnotify_group and hold a reference for the group returned.
*/
-struct fsnotify_group *fsnotify_obtain_group(unsigned int group_num, __u32 mask,
- const struct fsnotify_ops *ops)
+struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
{
- struct fsnotify_group *group, *tgroup;
+ struct fsnotify_group *group;
- /* very low use, simpler locking if we just always alloc */
- group = kmalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
+ group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL);
if (!group)
return ERR_PTR(-ENOMEM);
+ /* set to 0 when there a no external references to this group */
atomic_set(&group->refcnt, 1);
-
- group->on_group_list = 0;
- group->group_num = group_num;
- group->mask = mask;
+ /*
+ * hits 0 when there are no external references AND no marks for
+ * this group
+ */
+ atomic_set(&group->num_marks, 1);
mutex_init(&group->notification_mutex);
INIT_LIST_HEAD(&group->notification_list);
init_waitqueue_head(&group->notification_waitq);
- group->q_len = 0;
group->max_events = UINT_MAX;
spin_lock_init(&group->mark_lock);
- atomic_set(&group->num_marks, 0);
- INIT_LIST_HEAD(&group->mark_entries);
+ INIT_LIST_HEAD(&group->marks_list);
group->ops = ops;
- mutex_lock(&fsnotify_grp_mutex);
- tgroup = fsnotify_find_group(group_num, mask, ops);
- if (tgroup) {
- /* group already exists */
- mutex_unlock(&fsnotify_grp_mutex);
- /* destroy the new one we made */
- fsnotify_put_group(group);
- return tgroup;
- }
-
- /* group not found, add a new one */
- list_add_rcu(&group->group_list, &fsnotify_groups);
- group->on_group_list = 1;
- /* being on the fsnotify_groups list holds one num_marks */
- atomic_inc(&group->num_marks);
-
- mutex_unlock(&fsnotify_grp_mutex);
-
- if (mask)
- fsnotify_recalc_global_mask();
-
return group;
}
git://bbs.cooldavid.org / net-next-2.6.git / blobdiff