1 files changed, 79 insertions, 0 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
new file mode 100644
index 000000000000..56bee0f10c38
--- /dev/null
+++ b/fs/notify/fsnotify.c
@@ -0,0 +1,79 @@
+/*
+ *  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.
+ */
+
+#include <linux/dcache.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/srcu.h>
+
+#include <linux/fsnotify_backend.h>
+#include "fsnotify.h"
+
+/*
+ * This is the main call to fsnotify.  The VFS calls into hook specific functions
+ * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
+ * out to all of the registered fsnotify_group.  Those groups can then use the
+ * notification event in whatever means they feel necessary.
+ */
+void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
+{
+        struct fsnotify_group *group;
+        struct fsnotify_event *event = NULL;
+        int idx;
+
+        if (list_empty(&fsnotify_groups))
+                return;
+
+        if (!(mask & fsnotify_mask))
+                return;
+
+        /*
+         * SRCU!!  the groups list is very very much read only and the path is
+         * very hot.  The VAST majority of events are not going to need to do
+         * anything other than walk the list so it's crazy to pre-allocate.
+         */
+        idx = srcu_read_lock(&fsnotify_grp_srcu);
+        list_for_each_entry_rcu(group, &fsnotify_groups, group_list) {
+                if (mask & group->mask) {
+                        if (!event) {
+                                event = fsnotify_create_event(to_tell, mask, data, data_is);
+                                /* shit, we OOM'd and now we can't tell, maybe
+                                 * someday someone else will want to do something
+                                 * here */
+                                if (!event)
+                                        break;
+                        }
+                        group->ops->handle_event(group, event);
+                }
+        }
+        srcu_read_unlock(&fsnotify_grp_srcu, idx);
+        /*
+         * fsnotify_create_event() took a reference so the event can't be cleaned
+         * up while we are still trying to add it to lists, drop that one.
+         */
+        if (event)
+                fsnotify_put_event(event);
+}
+EXPORT_SYMBOL_GPL(fsnotify);
+
+static __init int fsnotify_init(void)
+{
+        return init_srcu_struct(&fsnotify_grp_srcu);
+}
+subsys_initcall(fsnotify_init);