LXR linux/fs/notify/inotify/inotify

   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 */
  39static 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
  56static 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
  65int 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, const 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                const 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
 123static 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 */
 135static 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
 163static 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
 174static void inotify_free_event(struct fsnotify_event *fsn_event)
 175{
 176        kfree(INOTIFY_E(fsn_event));
 177}
 178
 179const 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};
 185