#include <linux/fsnotify_backend.h>
#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);
/**
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;
+ group->ops->free_event(event);
}
/*
* 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 *fsnotify_add_notify_event(struct fsnotify_group *group,
+ struct fsnotify_event *event,
struct fsnotify_event *(*merge)(struct list_head *,
struct fsnotify_event *))
{
struct fsnotify_event *return_event = NULL;
- struct fsnotify_event_holder *holder = NULL;
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);
+ /* Queue overflow event only if it isn't already queued */
+ if (list_empty(&group->overflow_event.list))
+ event = &group->overflow_event;
return_event = event;
-
- /* sorry, no private data on the overflow event */
- priv = NULL;
}
if (!list_empty(list) && merge) {
- struct fsnotify_event *tmp;
-
- tmp = merge(list, event);
- if (tmp) {
- mutex_unlock(&group->notification_mutex);
-
- if (return_event)
- fsnotify_put_event(return_event);
- if (holder != &event->holder)
- fsnotify_destroy_event_holder(holder);
- return tmp;
- }
- }
-
- 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);
-
+ return_event = merge(list, event);
if (return_event) {
- fsnotify_put_event(return_event);
- return_event = NULL;
+ mutex_unlock(&group->notification_mutex);
+ return return_event;
}
-
- goto alloc_holder;
}
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);
}
/*
- * 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 *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);
+ list_del(&event->list);
group->q_len--;
return event;
*/
struct fsnotify_event *fsnotify_peek_notify_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);
}
/*
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 */
+ 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);
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