[T106][ZXW-22]7520V3SCV2.01.01.02P42U09_VEC_V0.8_AP_VEC origin source commit
Change-Id: Ic6e05d89ecd62fc34f82b23dcf306c93764aec4b
diff --git a/ap/os/linux/linux-3.4.x/fs/notify/notification.c b/ap/os/linux/linux-3.4.x/fs/notify/notification.c
new file mode 100644
index 0000000..c887b13
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/fs/notify/notification.c
@@ -0,0 +1,463 @@
+/*
+ * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING. If not, write to
+ * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+ * Basic idea behind the notification queue: An fsnotify group (like inotify)
+ * sends the userspace notification about events asyncronously some time after
+ * the event happened. When inotify gets an event it will need to add that
+ * event to the group notify queue. Since a single event might need to be on
+ * multiple group's notification queues we can't add the event directly to each
+ * queue and instead add a small "event_holder" to each queue. This event_holder
+ * has a pointer back to the original event. Since the majority of events are
+ * going to end up on one, and only one, notification queue we embed one
+ * event_holder into each event. This means we have a single allocation instead
+ * of always needing two. If the embedded event_holder is already in use by
+ * another group a new event_holder (from fsnotify_event_holder_cachep) will be
+ * allocated and used.
+ */
+
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/mutex.h>
+#include <linux/namei.h>
+#include <linux/path.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include <linux/atomic.h>
+
+#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);
+
+/**
+ * fsnotify_get_cookie - return a unique cookie for use in synchronizing events.
+ * Called from fsnotify_move, which is inlined into filesystem modules.
+ */
+u32 fsnotify_get_cookie(void)
+{
+ return atomic_inc_return(&fsnotify_sync_cookie);
+}
+EXPORT_SYMBOL_GPL(fsnotify_get_cookie);
+
+/* return true if the notify queue is empty, false otherwise */
+bool fsnotify_notify_queue_is_empty(struct fsnotify_group *group)
+{
+ BUG_ON(!mutex_is_locked(&group->notification_mutex));
+ return list_empty(&group->notification_list) ? true : false;
+}
+
+void fsnotify_get_event(struct fsnotify_event *event)
+{
+ atomic_inc(&event->refcnt);
+}
+
+void fsnotify_put_event(struct fsnotify_event *event)
+{
+ if (!event)
+ 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;
+}
+
+/*
+ * 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 *))
+{
+ 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);
+ }
+
+ 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 (!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);
+
+ if (return_event) {
+ fsnotify_put_event(return_event);
+ return_event = NULL;
+ }
+
+ 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);
+ mutex_unlock(&group->notification_mutex);
+
+ wake_up(&group->notification_waitq);
+ return return_event;
+}
+
+/*
+ * 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.
+ */
+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);
+
+ group->q_len--;
+
+ return event;
+}
+
+/*
+ * This will not remove the event, that must be done with fsnotify_remove_notify_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;
+}
+
+/*
+ * Called when a group is being torn down to clean up any outstanding
+ * event notifications.
+ */
+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 */
+ }
+ 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
+ * 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)
+{
+ 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();
+ }
+
+ 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);