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 #include <linux/sched.h>
  32
  33 #include "inotify.h"
  34
  35 static int inotify_handle_event(struct fsnotify_group *group, struct fsnotify_event *event)
  36 {
  37         struct fsnotify_mark_entry *entry;
  38         struct inotify_inode_mark_entry *ientry;
  39         struct inode *to_tell;
  40         struct inotify_event_private_data *event_priv;
  41         struct fsnotify_event_private_data *fsn_event_priv;
  42         int wd, ret;
  43
  44         to_tell = event->to_tell;
  45
  46         spin_lock(&to_tell->i_lock);
  47         entry = fsnotify_find_mark_entry(group, to_tell);
  48         spin_unlock(&to_tell->i_lock);
  49         /* race with watch removal?  We already passes should_send */
  50         if (unlikely(!entry))
  51                 return 0;
  52         ientry = container_of(entry, struct inotify_inode_mark_entry,
  53                               fsn_entry);
  54         wd = ientry->wd;
  55
  56         event_priv = kmem_cache_alloc(event_priv_cachep, GFP_KERNEL);
  57         if (unlikely(!event_priv))
  58                 return -ENOMEM;
  59
  60         fsn_event_priv = &event_priv->fsnotify_event_priv_data;
  61
  62         fsn_event_priv->group = group;
  63         event_priv->wd = wd;
  64
  65         ret = fsnotify_add_notify_event(group, event, fsn_event_priv);
  66         if (ret) {
  67                 inotify_free_event_priv(fsn_event_priv);
  68                 /* EEXIST says we tail matched, EOVERFLOW isn't something
  69                  * to report up the stack. */
  70                 if ((ret == -EEXIST) ||
  71                     (ret == -EOVERFLOW))
  72                         ret = 0;
  73         }
  74
  75         /*
  76          * If we hold the entry until after the event is on the queue
  77          * IN_IGNORED won't be able to pass this event in the queue
  78          */
  79         fsnotify_put_mark(entry);
  80
  81         return ret;
  82 }
  83
  84 static void inotify_freeing_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group)
  85 {
  86         inotify_ignored_and_remove_idr(entry, group);
  87 }
  88
  89 static bool inotify_should_send_event(struct fsnotify_group *group, struct inode *inode, __u32 mask)
  90 {
  91         struct fsnotify_mark_entry *entry;
  92         bool send;
  93
  94         spin_lock(&inode->i_lock);
  95         entry = fsnotify_find_mark_entry(group, inode);
  96         spin_unlock(&inode->i_lock);
  97         if (!entry)
  98                 return false;
  99
 100         mask = (mask & ~FS_EVENT_ON_CHILD);
 101         send = (entry->mask & mask);
 102
 103         /* find took a reference */
 104         fsnotify_put_mark(entry);
 105
 106         return send;
 107 }
 108
 109 /*
 110  * This is NEVER supposed to be called.  Inotify marks should either have been
 111  * removed from the idr when the watch was removed or in the
 112  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 113  * torn down.  This is only called if the idr is about to be freed but there
 114  * are still marks in it.
 115  */
 116 static int idr_callback(int id, void *p, void *data)
 117 {
 118         struct fsnotify_mark_entry *entry;
 119         struct inotify_inode_mark_entry *ientry;
 120         static bool warned = false;
 121
 122         if (warned)
 123                 return 0;
 124
 125         warned = true;
 126         entry = p;
 127         ientry = container_of(entry, struct inotify_inode_mark_entry, fsn_entry);
 128
 129         WARN(1, "inotify closing but id=%d for entry=%p in group=%p still in "
 130                 "idr.  Probably leaking memory\n", id, p, data);
 131
 132         /*
 133          * I'm taking the liberty of assuming that the mark in question is a
 134          * valid address and I'm dereferencing it.  This might help to figure
 135          * out why we got here and the panic is no worse than the original
 136          * BUG() that was here.
 137          */
 138         if (entry)
 139                 printk(KERN_WARNING "entry->group=%p inode=%p wd=%d\n",
 140                         entry->group, entry->inode, ientry->wd);
 141         return 0;
 142 }
 143
 144 static void inotify_free_group_priv(struct fsnotify_group *group)
 145 {
 146         /* ideally the idr is empty and we won't hit the BUG in teh callback */
 147         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 148         idr_remove_all(&group->inotify_data.idr);
 149         idr_destroy(&group->inotify_data.idr);
 150         free_uid(group->inotify_data.user);
 151 }
 152
 153 void inotify_free_event_priv(struct fsnotify_event_private_data *fsn_event_priv)
 154 {
 155         struct inotify_event_private_data *event_priv;
 156
 157
 158         event_priv = container_of(fsn_event_priv, struct inotify_event_private_data,
 159                                   fsnotify_event_priv_data);
 160
 161         kmem_cache_free(event_priv_cachep, event_priv);
 162 }
 163
 164 const struct fsnotify_ops inotify_fsnotify_ops = {
 165         .handle_event = inotify_handle_event,
 166         .should_send_event = inotify_should_send_event,
 167         .free_group_priv = inotify_free_group_priv,
 168         .free_event_priv = inotify_free_event_priv,
 169         .freeing_mark = inotify_freeing_mark,
 170 };