fs/notify/inotify/inotify_fsnotify.c

   1 /*
   2  * fs/inotify_user.c - inotify support for userspace
   3  *
   4  * Authors:
   5  *      John McCutchan  <ttb@tentacle.dhs.org>
   6  *      Robert Love     <rml@novell.com>
   7  *
   8  * Copyright (C) 2005 John McCutchan
   9  * Copyright 2006 Hewlett-Packard Development Company, L.P.
  10  *
  11  * Copyright (C) 2009 Eric Paris <Red Hat Inc>
  12  * inotify was largely rewriten to make use of the fsnotify infrastructure
  13  *
  14  * This program is free software; you can redistribute it and/or modify it
  15  * under the terms of the GNU General Public License as published by the
  16  * Free Software Foundation; either version 2, or (at your option) any
  17  * later version.
  18  *
  19  * This program is distributed in the hope that it will be useful, but
  20  * WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22  * General Public License for more details.
  23  */
  24
  25 #include <linux/fs.h> /* struct inode */
  26 #include <linux/fsnotify_backend.h>
  27 #include <linux/inotify.h>
  28 #include <linux/path.h> /* struct path */
  29 #include <linux/slab.h> /* kmem_* */
  30 #include <linux/types.h>
  31
  32 #include "inotify.h"
  33
  34 static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
  35 {
  36         struct fsnotify_mark_entry *entry;
  37         struct inotify_inode_mark_entry *ientry;
  38         struct inode *to_tell;
  39         struct inotify_event_private_data *event_priv;
  40         struct fsnotify_event_private_data *fsn_event_priv;
  41         int wd, ret;
  42
  43         to_tell = event->to_tell;
  44
  45         spin_lock(&to_tell->i_lock);
  46         entry = fsnotify_find_mark_entry(group, to_tell);
  47         spin_unlock(&to_tell->i_lock);
  48         /* race with watch removal?  We already passes should_send */
  49         if (unlikely(!entry))
  50                 return 0;
  51         ientry = container_of(entry, struct inotify_inode_mark_entry,
  52                               fsn_entry);
  53         wd = ientry->wd;
  54
  55         event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
  56         if (unlikely(!event_priv))
  57                 return -ENOMEM;
  58
  59         fsn_event_priv = &event_priv->fsnotify_event_priv_data;
  60
  61         fsn_event_priv->group = group;
  62         event_priv->wd = wd;
  63
  64         ret = fsnotify_add_notify_event(group, event, fsn_event_priv);
  65         /* EEXIST is not an error */
  66         if (ret == -EEXIST)
  67                 ret = 0;
  68
  69         /* did event_priv get attached? */
  70         if (list_empty(&fsn_event_priv->event_list))
  71                 inotify_free_event_priv(fsn_event_priv);
  72
  73         /*
  74          * If we hold the entry until after the event is on the queue
  75          * IN_IGNORED won't be able to pass this event in the queue
  76          */
  77         fsnotify_put_mark(entry);
  78
  79         return ret;
  80 }
  81
  82 static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
  83 {
  84         inotify_destroy_mark_entry(entry, group);
  85 }
  86
  87 static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
  88 {
  89         struct fsnotify_mark_entry *entry;
  90         bool send;
  91
  92         spin_lock(&inode->i_lock);
  93         entry = fsnotify_find_mark_entry(group, inode);
  94         spin_unlock(&inode->i_lock);
  95         if (!entry)
  96                 return false;
  97
  98         mask = (mask & ~FS_EVENT_ON_CHILD);
  99         send = (entry->mask & mask);
 100
 101         /* find took a reference */
 102         fsnotify_put_mark(entry);
 103
 104         return send;
 105 }
 106
 107 static int idr_callback(int id, void *p, void *data)
 108 {
 109         BUG();
 110         return 0;
 111 }
 112
 113 static void inotify_free_group_priv(struct fsnotify_group *group)
 114 {
 115         /* ideally the idr is empty and we won't hit the BUG in teh callback */
 116         idr_for_each(&group->inotify_data.idr, idr_callback, NULL);
 117         idr_remove_all(&group->inotify_data.idr);
 118         idr_destroy(&group->inotify_data.idr);
 119 }
 120
 121 void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
 122 {
 123         struct inotify_event_private_data *event_priv;
 124
 125
 126         event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
 127                                   fsnotify_event_priv_data);
 128
 129         kmem_cache_free(event_priv_cachep, event_priv);
 130 }
 131
 132 const struct fsnotify_ops inotify_fsnotify_ops = {
 133         .handle_event = inotify_handle_event,
 134         .should_send_event = inotify_should_send_event,
 135         .free_group_priv = inotify_free_group_priv,
 136         .free_event_priv = inotify_free_event_priv,
 137         .freeing_mark = inotify_freeing_mark,
 138 };