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Linux/fs/notify/inotify/inotify_fsnotify.c

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  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_notify_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->i.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         atomic_dec(&group->inotify_data.user->inotify_devs);
169         free_uid(group->inotify_data.user);
170 }
171 
172 static void inotify_free_event(struct fsnotify_event *fsn_event)
173 {
174         kfree(INOTIFY_E(fsn_event));
175 }
176 
177 const struct fsnotify_ops inotify_fsnotify_ops = {
178         .handle_event = inotify_handle_event,
179         .free_group_priv = inotify_free_group_priv,
180         .free_event = inotify_free_event,
181         .freeing_mark = inotify_freeing_mark,
182 };
183 

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