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         if (ret) {
  66                 inotify_free_event_priv(fsn_event_priv);
  67                 /* EEXIST says we tail matched, EOVERFLOW isn't something
  68                  * to report up the stack. */
  69                 if ((ret == -EEXIST) ||
  70                     (ret == -EOVERFLOW))
  71                         ret = 0;
  72         }
  73
  74         /*
  75          * If we hold the entry until after the event is on the queue
  76          * IN_IGNORED won't be able to pass this event in the queue
  77          */
  78         fsnotify_put_mark(entry);
  79
  80         return ret;
  81 }
  82
  83 static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
  84 {
  85         inotify_ignored_and_remove_idr(entry, group);
  86 }
  87
  88 static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
  89 {
  90         struct fsnotify_mark_entry *entry;
  91         bool send;
  92
  93         spin_lock(&inode->i_lock);
  94         entry = fsnotify_find_mark_entry(group, inode);
  95         spin_unlock(&inode->i_lock);
  96         if (!entry)
  97                 return false;
  98
  99         mask = (mask & ~FS_EVENT_ON_CHILD);
 100         send = (entry->mask & mask);
 101
 102         /* find took a reference */
 103         fsnotify_put_mark(entry);
 104
 105         return send;
 106 }
 107
 108 /*
 109  * This is NEVER supposed to be called.  Inotify marks should either have been
 110  * removed from the idr when the watch was removed or in the
 111  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 112  * torn down.  This is only called if the idr is about to be freed but there
 113  * are still marks in it.
 114  */
 115 static int idr_callback(int id, void *p, void *data)
 116 {
 117         struct fsnotify_mark_entry *entry;
 118         struct inotify_inode_mark_entry *ientry;
 119         static bool warned = false;
 120
 121         if (warned)
 122                 return 0;
 123
 124         warned = true;
 125         entry = p;
 126         ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
 127
 128         WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in "
 129                 "idr.  Probably leaking memory\n", id, p, data);
 130
 131         /*
 132          * I'm taking the liberty of assuming that the mark in question is a
 133          * valid address and I'm dereferencing it.  This might help to figure
 134          * out why we got here and the panic is no worse than the original
 135          * BUG() that was here.
 136          */
 137         if (entry)
 138                 printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n",
 139                         entry->group, entry->inode, ientry->wd);
 140         return 0;
 141 }
 142
 143 static void inotify_free_group_priv(struct fsnotify_group *group)
 144 {
 145         /* ideally the idr is empty and we won't hit the BUG in teh callback */
 146         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 147         idr_remove_all(&group->inotify_data.idr);
 148         idr_destroy(&group->inotify_data.idr);
 149 }
 150
 151 void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
 152 {
 153         struct inotify_event_private_data *event_priv;
 154
 155
 156         event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
 157                                   fsnotify_event_priv_data);
 158
 159         kmem_cache_free(event_priv_cachep, event_priv);
 160 }
 161
 162 const struct fsnotify_ops inotify_fsnotify_ops = {
 163         .handle_event = inotify_handle_event,
 164         .should_send_event = inotify_should_send_event,
 165         .free_group_priv = inotify_free_group_priv,
 166         .free_event_priv = inotify_free_event_priv,
 167         .freeing_mark = inotify_freeing_mark,
 168 };