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/dcache.h> /* d_unlinked */
  26 #include <linux/fs.h> /* struct inode */
  27 #include <linux/fsnotify_backend.h>
  28 #include <linux/inotify.h>
  29 #include <linux/path.h> /* struct path */
  30 #include <linux/slab.h> /* kmem_* */
  31 #include <linux/types.h>
  32 #include <linux/sched.h>
  33
  34 #include "inotify.h"
  35
  36 /*
  37  * Check if 2 events contain the same information.
  38  */
  39 static bool event_compare(struct fsnotify_event *old_fsn,
  40                           struct fsnotify_event *new_fsn)
  41 {
  42         struct inotify_event_info *old, *new;
  43
  44         if (old_fsn->mask & FS_IN_IGNORED)
  45                 return false;
  46         old = INOTIFY_E(old_fsn);
  47         new = INOTIFY_E(new_fsn);
  48         if ((old_fsn->mask == new_fsn->mask) &&
  49             (old_fsn->inode == new_fsn->inode) &&
  50             (old->name_len == new->name_len) &&
  51             (!old->name_len || !strcmp(old->name, new->name)))
  52                 return true;
  53         return false;
  54 }
  55
  56 static int inotify_merge(struct list_head *list,
  57                           struct fsnotify_event *event)
  58 {
  59         struct fsnotify_event *last_event;
  60
  61         last_event = list_entry(list->prev, struct fsnotify_event, list);
  62         return event_compare(last_event, event);
  63 }
  64
  65 int inotify_handle_event(struct fsnotify_group *group,
  66                          struct inode *inode,
  67                          struct fsnotify_mark *inode_mark,
  68                          struct fsnotify_mark *vfsmount_mark,
  69                          u32 mask, void *data, int data_type,
  70                          const unsigned char *file_name, u32 cookie)
  71 {
  72         struct inotify_inode_mark *i_mark;
  73         struct inotify_event_info *event;
  74         struct fsnotify_event *fsn_event;
  75         int ret;
  76         int len = 0;
  77         int alloc_len = sizeof(struct inotify_event_info);
  78
  79         BUG_ON(vfsmount_mark);
  80
  81         if ((inode_mark->mask & FS_EXCL_UNLINK) &&
  82             (data_type == FSNOTIFY_EVENT_PATH)) {
  83                 struct path *path = data;
  84
  85                 if (d_unlinked(path->dentry))
  86                         return 0;
  87         }
  88         if (file_name) {
  89                 len = strlen(file_name);
  90                 alloc_len += len + 1;
  91         }
  92
  93         pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
  94                  mask);
  95
  96         i_mark = container_of(inode_mark, struct inotify_inode_mark,
  97                               fsn_mark);
  98
  99         event = kmalloc(alloc_len, GFP_KERNEL);
 100         if (unlikely(!event))
 101                 return -ENOMEM;
 102
 103         fsn_event = &event->fse;
 104         fsnotify_init_event(fsn_event, inode, mask);
 105         event->wd = i_mark->wd;
 106         event->sync_cookie = cookie;
 107         event->name_len = len;
 108         if (len)
 109                 strcpy(event->name, file_name);
 110
 111         ret = fsnotify_add_event(group, fsn_event, inotify_merge);
 112         if (ret) {
 113                 /* Our event wasn't used in the end. Free it. */
 114                 fsnotify_destroy_event(group, fsn_event);
 115         }
 116
 117         if (inode_mark->mask & IN_ONESHOT)
 118                 fsnotify_destroy_mark(inode_mark, group);
 119
 120         return 0;
 121 }
 122
 123 static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
 124 {
 125         inotify_ignored_and_remove_idr(fsn_mark, group);
 126 }
 127
 128 /*
 129  * This is NEVER supposed to be called.  Inotify marks should either have been
 130  * removed from the idr when the watch was removed or in the
 131  * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 132  * torn down.  This is only called if the idr is about to be freed but there
 133  * are still marks in it.
 134  */
 135 static int idr_callback(int id, void *p, void *data)
 136 {
 137         struct fsnotify_mark *fsn_mark;
 138         struct inotify_inode_mark *i_mark;
 139         static bool warned = false;
 140
 141         if (warned)
 142                 return 0;
 143
 144         warned = true;
 145         fsn_mark = p;
 146         i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);
 147
 148         WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
 149                 "idr.  Probably leaking memory\n", id, p, data);
 150
 151         /*
 152          * I'm taking the liberty of assuming that the mark in question is a
 153          * valid address and I'm dereferencing it.  This might help to figure
 154          * out why we got here and the panic is no worse than the original
 155          * BUG() that was here.
 156          */
 157         if (fsn_mark)
 158                 printk(KERN_WARNING "fsn_mark->group=%p inode=%p wd=%d\n",
 159                         fsn_mark->group, fsn_mark->inode, i_mark->wd);
 160         return 0;
 161 }
 162
 163 static void inotify_free_group_priv(struct fsnotify_group *group)
 164 {
 165         /* ideally the idr is empty and we won't hit the BUG in the callback */
 166         idr_for_each(&group->inotify_data.idr, idr_callback, group);
 167         idr_destroy(&group->inotify_data.idr);
 168         if (group->inotify_data.user) {
 169                 atomic_dec(&group->inotify_data.user->inotify_devs);
 170                 free_uid(group->inotify_data.user);
 171         }
 172 }
 173
 174 static void inotify_free_event(struct fsnotify_event *fsn_event)
 175 {
 176         kfree(INOTIFY_E(fsn_event));
 177 }
 178
 179 const struct fsnotify_ops inotify_fsnotify_ops = {
 180         .handle_event = inotify_handle_event,
 181         .free_group_priv = inotify_free_group_priv,
 182         .free_event = inotify_free_event,
 183         .freeing_mark = inotify_freeing_mark,
 184 };