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
|
/*
* Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com>
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/dcache.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/srcu.h>
#include <linux/fsnotify_backend.h>
#include "fsnotify.h"
/*
* This is the main call to fsnotify. The VFS calls into hook specific functions
* in linux/fsnotify.h. Those functions then in turn call here. Here will call
* out to all of the registered fsnotify_group. Those groups can then use the
* notification event in whatever means they feel necessary.
*/
void fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is)
{
struct fsnotify_group *group;
struct fsnotify_event *event = NULL;
int idx;
if (list_empty(&fsnotify_groups))
return;
if (!(mask & fsnotify_mask))
return;
/*
* SRCU!! the groups list is very very much read only and the path is
* very hot. The VAST majority of events are not going to need to do
* anything other than walk the list so it's crazy to pre-allocate.
*/
idx = srcu_read_lock(&fsnotify_grp_srcu);
list_for_each_entry_rcu(group, &fsnotify_groups, group_list) {
if (mask & group->mask) {
if (!event) {
event = fsnotify_create_event(to_tell, mask, data, data_is);
/* shit, we OOM'd and now we can't tell, maybe
* someday someone else will want to do something
* here */
if (!event)
break;
}
group->ops->handle_event(group, event);
}
}
srcu_read_unlock(&fsnotify_grp_srcu, idx);
/*
* fsnotify_create_event() took a reference so the event can't be cleaned
* up while we are still trying to add it to lists, drop that one.
*/
if (event)
fsnotify_put_event(event);
}
EXPORT_SYMBOL_GPL(fsnotify);
static __init int fsnotify_init(void)
{
return init_srcu_struct(&fsnotify_grp_srcu);
}
subsys_initcall(fsnotify_init);
|
