]>
Commit | Line | Data |
---|---|---|
1 | /* | |
2 | * Copyright (C) 2008 Red Hat, Inc., Eric Paris <eparis@redhat.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2, or (at your option) | |
7 | * any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; see the file COPYING. If not, write to | |
16 | * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. | |
17 | */ | |
18 | ||
19 | #include <linux/list.h> | |
20 | #include <linux/mutex.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/srcu.h> | |
23 | #include <linux/rculist.h> | |
24 | #include <linux/wait.h> | |
25 | ||
26 | #include <linux/fsnotify_backend.h> | |
27 | #include "fsnotify.h" | |
28 | ||
29 | #include <asm/atomic.h> | |
30 | ||
31 | /* | |
32 | * Final freeing of a group | |
33 | */ | |
34 | void fsnotify_final_destroy_group(struct fsnotify_group *group) | |
35 | { | |
36 | /* clear the notification queue of all events */ | |
37 | fsnotify_flush_notify(group); | |
38 | ||
39 | if (group->ops->free_group_priv) | |
40 | group->ops->free_group_priv(group); | |
41 | ||
42 | kfree(group); | |
43 | } | |
44 | ||
45 | /* | |
46 | * Trying to get rid of a group. We need to first get rid of any outstanding | |
47 | * allocations and then free the group. Remember that fsnotify_clear_marks_by_group | |
48 | * could miss marks that are being freed by inode and those marks could still | |
49 | * hold a reference to this group (via group->num_marks) If we get into that | |
50 | * situtation, the fsnotify_final_destroy_group will get called when that final | |
51 | * mark is freed. | |
52 | */ | |
53 | static void fsnotify_destroy_group(struct fsnotify_group *group) | |
54 | { | |
55 | /* clear all inode marks for this group */ | |
56 | fsnotify_clear_marks_by_group(group); | |
57 | ||
58 | synchronize_srcu(&fsnotify_mark_srcu); | |
59 | ||
60 | /* past the point of no return, matches the initial value of 1 */ | |
61 | if (atomic_dec_and_test(&group->num_marks)) | |
62 | fsnotify_final_destroy_group(group); | |
63 | } | |
64 | ||
65 | /* | |
66 | * Drop a reference to a group. Free it if it's through. | |
67 | */ | |
68 | void fsnotify_put_group(struct fsnotify_group *group) | |
69 | { | |
70 | if (atomic_dec_and_test(&group->refcnt)) | |
71 | fsnotify_destroy_group(group); | |
72 | } | |
73 | ||
74 | /* | |
75 | * Create a new fsnotify_group and hold a reference for the group returned. | |
76 | */ | |
77 | struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops) | |
78 | { | |
79 | struct fsnotify_group *group; | |
80 | ||
81 | group = kzalloc(sizeof(struct fsnotify_group), GFP_KERNEL); | |
82 | if (!group) | |
83 | return ERR_PTR(-ENOMEM); | |
84 | ||
85 | /* set to 0 when there a no external references to this group */ | |
86 | atomic_set(&group->refcnt, 1); | |
87 | /* | |
88 | * hits 0 when there are no external references AND no marks for | |
89 | * this group | |
90 | */ | |
91 | atomic_set(&group->num_marks, 1); | |
92 | ||
93 | mutex_init(&group->notification_mutex); | |
94 | INIT_LIST_HEAD(&group->notification_list); | |
95 | init_waitqueue_head(&group->notification_waitq); | |
96 | group->max_events = UINT_MAX; | |
97 | ||
98 | spin_lock_init(&group->mark_lock); | |
99 | INIT_LIST_HEAD(&group->marks_list); | |
100 | ||
101 | group->ops = ops; | |
102 | ||
103 | return group; | |
104 | } |