summaryrefslogtreecommitdiffstats
path: root/fs/notify/inotify/inotify_fsnotify.c
blob: 8b73332735ba5071f67c5f39b6079c506cdea6f7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
/*
 * fs/inotify_user.c - inotify support for userspace
 *
 * Authors:
 *	John McCutchan	<ttb@tentacle.dhs.org>
 *	Robert Love	<rml@novell.com>
 *
 * Copyright (C) 2005 John McCutchan
 * Copyright 2006 Hewlett-Packard Development Company, L.P.
 *
 * Copyright (C) 2009 Eric Paris <Red Hat Inc>
 * inotify was largely rewriten to make use of the fsnotify infrastructure
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#include <linux/dcache.h> /* d_unlinked */
#include <linux/fs.h> /* struct inode */
#include <linux/fsnotify_backend.h>
#include <linux/inotify.h>
#include <linux/path.h> /* struct path */
#include <linux/slab.h> /* kmem_* */
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/sched/user.h>

#include "inotify.h"

/*
 * Check if 2 events contain the same information.
 */
static bool event_compare(struct fsnotify_event *old_fsn,
			  struct fsnotify_event *new_fsn)
{
	struct inotify_event_info *old, *new;

	if (old_fsn->mask & FS_IN_IGNORED)
		return false;
	old = INOTIFY_E(old_fsn);
	new = INOTIFY_E(new_fsn);
	if ((old_fsn->mask == new_fsn->mask) &&
	    (old_fsn->inode == new_fsn->inode) &&
	    (old->name_len == new->name_len) &&
	    (!old->name_len || !strcmp(old->name, new->name)))
		return true;
	return false;
}

static int inotify_merge(struct list_head *list,
			  struct fsnotify_event *event)
{
	struct fsnotify_event *last_event;

	last_event = list_entry(list->prev, struct fsnotify_event, list);
	return event_compare(last_event, event);
}

int inotify_handle_event(struct fsnotify_group *group,
			 struct inode *inode,
			 struct fsnotify_mark *inode_mark,
			 struct fsnotify_mark *vfsmount_mark,
			 u32 mask, const void *data, int data_type,
			 const unsigned char *file_name, u32 cookie,
			 struct fsnotify_iter_info *iter_info)
{
	struct inotify_inode_mark *i_mark;
	struct inotify_event_info *event;
	struct fsnotify_event *fsn_event;
	int ret;
	int len = 0;
	int alloc_len = sizeof(struct inotify_event_info);

	BUG_ON(vfsmount_mark);

	if ((inode_mark->mask & FS_EXCL_UNLINK) &&
	    (data_type == FSNOTIFY_EVENT_PATH)) {
		const struct path *path = data;

		if (d_unlinked(path->dentry))
			return 0;
	}
	if (file_name) {
		len = strlen(file_name);
		alloc_len += len + 1;
	}

	pr_debug("%s: group=%p inode=%p mask=%x\n", __func__, group, inode,
		 mask);

	i_mark = container_of(inode_mark, struct inotify_inode_mark,
			      fsn_mark);

	event = kmalloc(alloc_len, GFP_KERNEL);
	if (unlikely(!event))
		return -ENOMEM;

	fsn_event = &event->fse;
	fsnotify_init_event(fsn_event, inode, mask);
	event->wd = i_mark->wd;
	event->sync_cookie = cookie;
	event->name_len = len;
	if (len)
		strcpy(event->name, file_name);

	ret = fsnotify_add_event(group, fsn_event, inotify_merge);
	if (ret) {
		/* Our event wasn't used in the end. Free it. */
		fsnotify_destroy_event(group, fsn_event);
	}

	if (inode_mark->mask & IN_ONESHOT)
		fsnotify_destroy_mark(inode_mark, group);

	return 0;
}

static void inotify_freeing_mark(struct fsnotify_mark *fsn_mark, struct fsnotify_group *group)
{
	inotify_ignored_and_remove_idr(fsn_mark, group);
}

/*
 * This is NEVER supposed to be called.  Inotify marks should either have been
 * removed from the idr when the watch was removed or in the
 * fsnotify_destroy_mark_by_group() call when the inotify instance was being
 * torn down.  This is only called if the idr is about to be freed but there
 * are still marks in it.
 */
static int idr_callback(int id, void *p, void *data)
{
	struct fsnotify_mark *fsn_mark;
	struct inotify_inode_mark *i_mark;
	static bool warned = false;

	if (warned)
		return 0;

	warned = true;
	fsn_mark = p;
	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);

	WARN(1, "inotify closing but id=%d for fsn_mark=%p in group=%p still in "
		"idr.  Probably leaking memory\n", id, p, data);

	/*
	 * I'm taking the liberty of assuming that the mark in question is a
	 * valid address and I'm dereferencing it.  This might help to figure
	 * out why we got here and the panic is no worse than the original
	 * BUG() that was here.
	 */
	if (fsn_mark)
		printk(KERN_WARNING "fsn_mark->group=%p wd=%d\n",
			fsn_mark->group, i_mark->wd);
	return 0;
}

static void inotify_free_group_priv(struct fsnotify_group *group)
{
	/* ideally the idr is empty and we won't hit the BUG in the callback */
	idr_for_each(&group->inotify_data.idr, idr_callback, group);
	idr_destroy(&group->inotify_data.idr);
	if (group->inotify_data.ucounts)
		dec_inotify_instances(group->inotify_data.ucounts);
}

static void inotify_free_event(struct fsnotify_event *fsn_event)
{
	kfree(INOTIFY_E(fsn_event));
}

/* ding dong the mark is dead */
static void inotify_free_mark(struct fsnotify_mark *fsn_mark)
{
	struct inotify_inode_mark *i_mark;

	i_mark = container_of(fsn_mark, struct inotify_inode_mark, fsn_mark);

	kmem_cache_free(inotify_inode_mark_cachep, i_mark);
}

const struct fsnotify_ops inotify_fsnotify_ops = {
	.handle_event = inotify_handle_event,
	.free_group_priv = inotify_free_group_priv,
	.free_event = inotify_free_event,
	.freeing_mark = inotify_freeing_mark,
	.free_mark = inotify_free_mark,
};
OpenPOWER on IntegriCloud