--- zzzz-none-000/linux-3.10.107/fs/notify/notification.c 2017-06-27 09:49:32.000000000 +0000 +++ scorpion-7490-727/linux-3.10.107/fs/notify/notification.c 2021-02-04 17:41:59.000000000 +0000 @@ -48,15 +48,6 @@ #include #include "fsnotify.h" -static struct kmem_cache *fsnotify_event_cachep; -static struct kmem_cache *fsnotify_event_holder_cachep; -/* - * This is a magic event we send when the q is too full. Since it doesn't - * hold real event information we just keep one system wide and use it any time - * it is needed. It's refcnt is set 1 at kernel init time and will never - * get set to 0 so it will never get 'freed' - */ -static struct fsnotify_event *q_overflow_event; static atomic_t fsnotify_sync_cookie = ATOMIC_INIT(0); /** @@ -76,205 +67,104 @@ return list_empty(&group->notification_list) ? true : false; } -void fsnotify_get_event(struct fsnotify_event *event) +void fsnotify_destroy_event(struct fsnotify_group *group, + struct fsnotify_event *event) { - atomic_inc(&event->refcnt); -} - -void fsnotify_put_event(struct fsnotify_event *event) -{ - if (!event) + /* Overflow events are per-group and we don't want to free them */ + if (!event || event->mask == FS_Q_OVERFLOW) return; - - if (atomic_dec_and_test(&event->refcnt)) { - pr_debug("%s: event=%p\n", __func__, event); - - if (event->data_type == FSNOTIFY_EVENT_PATH) - path_put(&event->path); - - BUG_ON(!list_empty(&event->private_data_list)); - - kfree(event->file_name); - put_pid(event->tgid); - kmem_cache_free(fsnotify_event_cachep, event); - } -} - -struct fsnotify_event_holder *fsnotify_alloc_event_holder(void) -{ - return kmem_cache_alloc(fsnotify_event_holder_cachep, GFP_KERNEL); -} - -void fsnotify_destroy_event_holder(struct fsnotify_event_holder *holder) -{ - if (holder) - kmem_cache_free(fsnotify_event_holder_cachep, holder); -} - -/* - * Find the private data that the group previously attached to this event when - * the group added the event to the notification queue (fsnotify_add_notify_event) - */ -struct fsnotify_event_private_data *fsnotify_remove_priv_from_event(struct fsnotify_group *group, struct fsnotify_event *event) -{ - struct fsnotify_event_private_data *lpriv; - struct fsnotify_event_private_data *priv = NULL; - - assert_spin_locked(&event->lock); - - list_for_each_entry(lpriv, &event->private_data_list, event_list) { - if (lpriv->group == group) { - priv = lpriv; - list_del(&priv->event_list); - break; - } - } - return priv; + /* If the event is still queued, we have a problem... */ + WARN_ON(!list_empty(&event->list)); + group->ops->free_event(event); } /* * Add an event to the group notification queue. The group can later pull this - * event off the queue to deal with. If the event is successfully added to the - * group's notification queue, a reference is taken on event. - */ -struct fsnotify_event *fsnotify_add_notify_event(struct fsnotify_group *group, struct fsnotify_event *event, - struct fsnotify_event_private_data *priv, - struct fsnotify_event *(*merge)(struct list_head *, - struct fsnotify_event *)) + * event off the queue to deal with. The function returns 0 if the event was + * added to the queue, 1 if the event was merged with some other queued event, + * 2 if the event was not queued - either the queue of events has overflown + * or the group is shutting down. + */ +int fsnotify_add_event(struct fsnotify_group *group, + struct fsnotify_event *event, + int (*merge)(struct list_head *, + struct fsnotify_event *)) { - struct fsnotify_event *return_event = NULL; - struct fsnotify_event_holder *holder = NULL; + int ret = 0; struct list_head *list = &group->notification_list; - pr_debug("%s: group=%p event=%p priv=%p\n", __func__, group, event, priv); - - /* - * There is one fsnotify_event_holder embedded inside each fsnotify_event. - * Check if we expect to be able to use that holder. If not alloc a new - * holder. - * For the overflow event it's possible that something will use the in - * event holder before we get the lock so we may need to jump back and - * alloc a new holder, this can't happen for most events... - */ - if (!list_empty(&event->holder.event_list)) { -alloc_holder: - holder = fsnotify_alloc_event_holder(); - if (!holder) - return ERR_PTR(-ENOMEM); - } + pr_debug("%s: group=%p event=%p\n", __func__, group, event); mutex_lock(&group->notification_mutex); - if (group->q_len >= group->max_events) { - event = q_overflow_event; - - /* - * we need to return the overflow event - * which means we need a ref - */ - fsnotify_get_event(event); - return_event = event; - - /* sorry, no private data on the overflow event */ - priv = NULL; + if (group->shutdown) { + mutex_unlock(&group->notification_mutex); + return 2; } - if (!list_empty(list) && merge) { - struct fsnotify_event *tmp; - - tmp = merge(list, event); - if (tmp) { + if (group->q_len >= group->max_events) { + ret = 2; + /* Queue overflow event only if it isn't already queued */ + if (!list_empty(&group->overflow_event->list)) { mutex_unlock(&group->notification_mutex); - - if (return_event) - fsnotify_put_event(return_event); - if (holder != &event->holder) - fsnotify_destroy_event_holder(holder); - return tmp; + return ret; } + event = group->overflow_event; + goto queue; } - spin_lock(&event->lock); - - if (list_empty(&event->holder.event_list)) { - if (unlikely(holder)) - fsnotify_destroy_event_holder(holder); - holder = &event->holder; - } else if (unlikely(!holder)) { - /* between the time we checked above and got the lock the in - * event holder was used, go back and get a new one */ - spin_unlock(&event->lock); - mutex_unlock(&group->notification_mutex); - - if (return_event) { - fsnotify_put_event(return_event); - return_event = NULL; + if (!list_empty(list) && merge) { + ret = merge(list, event); + if (ret) { + mutex_unlock(&group->notification_mutex); + return ret; } - - goto alloc_holder; } +queue: group->q_len++; - holder->event = event; - - fsnotify_get_event(event); - list_add_tail(&holder->event_list, list); - if (priv) - list_add_tail(&priv->event_list, &event->private_data_list); - spin_unlock(&event->lock); + list_add_tail(&event->list, list); mutex_unlock(&group->notification_mutex); wake_up(&group->notification_waitq); kill_fasync(&group->fsn_fa, SIGIO, POLL_IN); - return return_event; + return ret; } /* - * Remove and return the first event from the notification list. There is a - * reference held on this event since it was on the list. It is the responsibility - * of the caller to drop this reference. + * Remove and return the first event from the notification list. It is the + * responsibility of the caller to destroy the obtained event */ -struct fsnotify_event *fsnotify_remove_notify_event(struct fsnotify_group *group) +struct fsnotify_event *fsnotify_remove_first_event(struct fsnotify_group *group) { struct fsnotify_event *event; - struct fsnotify_event_holder *holder; BUG_ON(!mutex_is_locked(&group->notification_mutex)); pr_debug("%s: group=%p\n", __func__, group); - holder = list_first_entry(&group->notification_list, struct fsnotify_event_holder, event_list); - - event = holder->event; - - spin_lock(&event->lock); - holder->event = NULL; - list_del_init(&holder->event_list); - spin_unlock(&event->lock); - - /* event == holder means we are referenced through the in event holder */ - if (holder != &event->holder) - fsnotify_destroy_event_holder(holder); - + event = list_first_entry(&group->notification_list, + struct fsnotify_event, list); + /* + * We need to init list head for the case of overflow event so that + * check in fsnotify_add_event() works + */ + list_del_init(&event->list); group->q_len--; return event; } /* - * This will not remove the event, that must be done with fsnotify_remove_notify_event() + * This will not remove the event, that must be done with + * fsnotify_remove_first_event() */ -struct fsnotify_event *fsnotify_peek_notify_event(struct fsnotify_group *group) +struct fsnotify_event *fsnotify_peek_first_event(struct fsnotify_group *group) { - struct fsnotify_event *event; - struct fsnotify_event_holder *holder; - BUG_ON(!mutex_is_locked(&group->notification_mutex)); - holder = list_first_entry(&group->notification_list, struct fsnotify_event_holder, event_list); - event = holder->event; - - return event; + return list_first_entry(&group->notification_list, + struct fsnotify_event, list); } /* @@ -284,181 +174,31 @@ void fsnotify_flush_notify(struct fsnotify_group *group) { struct fsnotify_event *event; - struct fsnotify_event_private_data *priv; mutex_lock(&group->notification_mutex); while (!fsnotify_notify_queue_is_empty(group)) { - event = fsnotify_remove_notify_event(group); - /* if they don't implement free_event_priv they better not have attached any */ - if (group->ops->free_event_priv) { - spin_lock(&event->lock); - priv = fsnotify_remove_priv_from_event(group, event); - spin_unlock(&event->lock); - if (priv) - group->ops->free_event_priv(priv); - } - fsnotify_put_event(event); /* matches fsnotify_add_notify_event */ + event = fsnotify_remove_first_event(group); + fsnotify_destroy_event(group, event); } mutex_unlock(&group->notification_mutex); } -static void initialize_event(struct fsnotify_event *event) -{ - INIT_LIST_HEAD(&event->holder.event_list); - atomic_set(&event->refcnt, 1); - - spin_lock_init(&event->lock); - - INIT_LIST_HEAD(&event->private_data_list); -} - -/* - * Caller damn well better be holding whatever mutex is protecting the - * old_holder->event_list and the new_event must be a clean event which - * cannot be found anywhere else in the kernel. - */ -int fsnotify_replace_event(struct fsnotify_event_holder *old_holder, - struct fsnotify_event *new_event) -{ - struct fsnotify_event *old_event = old_holder->event; - struct fsnotify_event_holder *new_holder = &new_event->holder; - - enum event_spinlock_class { - SPINLOCK_OLD, - SPINLOCK_NEW, - }; - - pr_debug("%s: old_event=%p new_event=%p\n", __func__, old_event, new_event); - - /* - * if the new_event's embedded holder is in use someone - * screwed up and didn't give us a clean new event. - */ - BUG_ON(!list_empty(&new_holder->event_list)); - - spin_lock_nested(&old_event->lock, SPINLOCK_OLD); - spin_lock_nested(&new_event->lock, SPINLOCK_NEW); - - new_holder->event = new_event; - list_replace_init(&old_holder->event_list, &new_holder->event_list); - - spin_unlock(&new_event->lock); - spin_unlock(&old_event->lock); - - /* event == holder means we are referenced through the in event holder */ - if (old_holder != &old_event->holder) - fsnotify_destroy_event_holder(old_holder); - - fsnotify_get_event(new_event); /* on the list take reference */ - fsnotify_put_event(old_event); /* off the list, drop reference */ - - return 0; -} - -struct fsnotify_event *fsnotify_clone_event(struct fsnotify_event *old_event) -{ - struct fsnotify_event *event; - - event = kmem_cache_alloc(fsnotify_event_cachep, GFP_KERNEL); - if (!event) - return NULL; - - pr_debug("%s: old_event=%p new_event=%p\n", __func__, old_event, event); - - memcpy(event, old_event, sizeof(*event)); - initialize_event(event); - - if (event->name_len) { - event->file_name = kstrdup(old_event->file_name, GFP_KERNEL); - if (!event->file_name) { - kmem_cache_free(fsnotify_event_cachep, event); - return NULL; - } - } - event->tgid = get_pid(old_event->tgid); - if (event->data_type == FSNOTIFY_EVENT_PATH) - path_get(&event->path); - - return event; -} - /* * fsnotify_create_event - Allocate a new event which will be sent to each * group's handle_event function if the group was interested in this * particular event. * - * @to_tell the inode which is supposed to receive the event (sometimes a + * @inode the inode which is supposed to receive the event (sometimes a * parent of the inode to which the event happened. * @mask what actually happened. * @data pointer to the object which was actually affected * @data_type flag indication if the data is a file, path, inode, nothing... * @name the filename, if available */ -struct fsnotify_event *fsnotify_create_event(struct inode *to_tell, __u32 mask, void *data, - int data_type, const unsigned char *name, - u32 cookie, gfp_t gfp) +void fsnotify_init_event(struct fsnotify_event *event, struct inode *inode, + u32 mask) { - struct fsnotify_event *event; - - event = kmem_cache_zalloc(fsnotify_event_cachep, gfp); - if (!event) - return NULL; - - pr_debug("%s: event=%p to_tell=%p mask=%x data=%p data_type=%d\n", - __func__, event, to_tell, mask, data, data_type); - - initialize_event(event); - - if (name) { - event->file_name = kstrdup(name, gfp); - if (!event->file_name) { - kmem_cache_free(fsnotify_event_cachep, event); - return NULL; - } - event->name_len = strlen(event->file_name); - } - - event->tgid = get_pid(task_tgid(current)); - event->sync_cookie = cookie; - event->to_tell = to_tell; - event->data_type = data_type; - - switch (data_type) { - case FSNOTIFY_EVENT_PATH: { - struct path *path = data; - event->path.dentry = path->dentry; - event->path.mnt = path->mnt; - path_get(&event->path); - break; - } - case FSNOTIFY_EVENT_INODE: - event->inode = data; - break; - case FSNOTIFY_EVENT_NONE: - event->inode = NULL; - event->path.dentry = NULL; - event->path.mnt = NULL; - break; - default: - BUG(); - } - + INIT_LIST_HEAD(&event->list); + event->inode = inode; event->mask = mask; - - return event; -} - -static __init int fsnotify_notification_init(void) -{ - fsnotify_event_cachep = KMEM_CACHE(fsnotify_event, SLAB_PANIC); - fsnotify_event_holder_cachep = KMEM_CACHE(fsnotify_event_holder, SLAB_PANIC); - - q_overflow_event = fsnotify_create_event(NULL, FS_Q_OVERFLOW, NULL, - FSNOTIFY_EVENT_NONE, NULL, 0, - GFP_KERNEL); - if (!q_overflow_event) - panic("unable to allocate fsnotify q_overflow_event\n"); - - return 0; } -subsys_initcall(fsnotify_notification_init);