inotify: reimplement inotify using fsnotify

Reimplement inotify_user using fsnotify.  This should be feature for feature
exactly the same as the original inotify_user.  This does not make any changes
to the in kernel inotify feature used by audit.  Those patches (and the eventual
removal of in kernel inotify) will come after the new inotify_user proves to be
working correctly.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

1 files changed, 137 insertions, 0 deletions

diff --git a/fs/notify/inotify/inotify_fsnotify.c b/fs/notify/inotify/inotify_fsnotify.c
new file mode 100644
index 000000000000..160da5486839
--- /dev/null
+++ b/fs/notify/inotify/inotify_fsnotify.c
@@ -0,0 +1,137 @@
+/*
+ * fs/inotify_user.c - inotify support for userspace
+ *
+ * Authors:
+ *      John McCutchan  <ttb@tentacle.dhs.org>
+ *      Robert Love     <rml@novell.com>
+ *
+ * Copyright (C) 2005 John McCutchan
+ * Copyright 2006 Hewlett-Packard Development Company, L.P.
+ *
+ * Copyright (C) 2009 Eric Paris <Red Hat Inc>
+ * inotify was largely rewriten to make use of the fsnotify infrastructure
+ *
+ * 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.
+ */
+
+#include <linux/fs.h> /* struct inode */
+#include <linux/fsnotify_backend.h>
+#include <linux/inotify.h>
+#include <linux/path.h> /* struct path */
+#include <linux/slab.h> /* kmem_* */
+#include <linux/types.h>
+
+#include "inotify.h"
+
+static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
+{
+        struct fsnotify_mark_entry *entry;
+        struct inotify_inode_mark_entry *ientry;
+        struct inode *to_tell;
+        struct inotify_event_private_data *event_priv;
+        struct fsnotify_event_private_data *fsn_event_priv;
+        int wd, ret;
+
+        to_tell = event->to_tell;
+
+        spin_lock(&to_tell->i_lock);
+        entry = fsnotify_find_mark_entry(group, to_tell);
+        spin_unlock(&to_tell->i_lock);
+        /* race with watch removal?  We already passes should_send */
+        if (unlikely(!entry))
+                return 0;
+        ientry = container_of(entry, struct inotify_inode_mark_entry,
+                              fsn_entry);
+        wd = ientry->wd;
+
+        event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
+        if (unlikely(!event_priv))
+                return -ENOMEM;
+
+        fsn_event_priv = &event_priv->fsnotify_event_priv_data;
+
+        fsn_event_priv->group = group;
+        event_priv->wd = wd;
+
+        ret = fsnotify_add_notify_event(group, event, fsn_event_priv);
+        /* EEXIST is not an error */
+        if (ret == -EEXIST)
+                ret = 0;
+
+        /* did event_priv get attached? */
+        if (list_empty(&fsn_event_priv->event_list))
+                inotify_free_event_priv(fsn_event_priv);
+
+        /*
+         * If we hold the entry until after the event is on the queue
+         * IN_IGNORED won't be able to pass this event in the queue
+         */
+        fsnotify_put_mark(entry);
+
+        return ret;
+}
+
+static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
+{
+        inotify_destroy_mark_entry(entry, group);
+}
+
+static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
+{
+        struct fsnotify_mark_entry *entry;
+        bool send;
+
+        spin_lock(&inode->i_lock);
+        entry = fsnotify_find_mark_entry(group, inode);
+        spin_unlock(&inode->i_lock);
+        if (!entry)
+                return false;
+
+        send = (entry->mask & mask);
+
+        /* find took a reference */
+        fsnotify_put_mark(entry);
+
+        return send;
+}
+
+static int idr_callback(int id, void *p, void *data)
+{
+        BUG();
+        return 0;
+}
+
+static void inotify_free_group_priv(struct fsnotify_group *group)
+{
+        /* ideally the idr is empty and we won't hit the BUG in teh callback */
+        idr_for_each(&group->inotify_data.idr, idr_callback, NULL);
+        idr_remove_all(&group->inotify_data.idr);
+        idr_destroy(&group->inotify_data.idr);
+}
+
+void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
+{
+        struct inotify_event_private_data *event_priv;
+
+
+        event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
+                                  fsnotify_event_priv_data);
+
+        kmem_cache_free(event_priv_cachep, event_priv);
+}
+
+const struct fsnotify_ops inotify_fsnotify_ops = {
+        .handle_event = inotify_handle_event,
+        .should_send_event = inotify_should_send_event,
+        .free_group_priv = inotify_free_group_priv,
+        .free_event_priv = inotify_free_event_priv,
+        .freeing_mark = inotify_freeing_mark,
+};