blob: fd8c9a5bcac44c74101d1b2ba4001c8785875254 [file] [log] [blame]
Jeff Laytonf7790022014-09-12 16:40:20 -04001/*
2 * Common code for control of lockd and nfsv4 grace periods.
3 *
4 * Transplanted from lockd code
5 */
6
7#include <linux/module.h>
8#include <net/net_namespace.h>
9#include <net/netns/generic.h>
10#include <linux/fs.h>
11
12static int grace_net_id;
13static DEFINE_SPINLOCK(grace_lock);
14
15/**
16 * locks_start_grace
17 * @net: net namespace that this lock manager belongs to
18 * @lm: who this grace period is for
19 *
20 * A grace period is a period during which locks should not be given
21 * out. Currently grace periods are only enforced by the two lock
22 * managers (lockd and nfsd), using the locks_in_grace() function to
23 * check when they are in a grace period.
24 *
25 * This function is called to start a grace period.
26 */
27void
28locks_start_grace(struct net *net, struct lock_manager *lm)
29{
30 struct list_head *grace_list = net_generic(net, grace_net_id);
31
32 spin_lock(&grace_lock);
33 list_add(&lm->list, grace_list);
34 spin_unlock(&grace_lock);
35}
36EXPORT_SYMBOL_GPL(locks_start_grace);
37
38/**
39 * locks_end_grace
40 * @net: net namespace that this lock manager belongs to
41 * @lm: who this grace period is for
42 *
43 * Call this function to state that the given lock manager is ready to
44 * resume regular locking. The grace period will not end until all lock
45 * managers that called locks_start_grace() also call locks_end_grace().
46 * Note that callers count on it being safe to call this more than once,
47 * and the second call should be a no-op.
48 */
49void
50locks_end_grace(struct lock_manager *lm)
51{
52 spin_lock(&grace_lock);
53 list_del_init(&lm->list);
54 spin_unlock(&grace_lock);
55}
56EXPORT_SYMBOL_GPL(locks_end_grace);
57
58/**
59 * locks_in_grace
60 *
61 * Lock managers call this function to determine when it is OK for them
62 * to answer ordinary lock requests, and when they should accept only
63 * lock reclaims.
64 */
65int
J. Bruce Fieldsc87fb4a2015-08-06 12:47:02 -040066__state_in_grace(struct net *net, bool open)
Jeff Laytonf7790022014-09-12 16:40:20 -040067{
68 struct list_head *grace_list = net_generic(net, grace_net_id);
J. Bruce Fieldsc87fb4a2015-08-06 12:47:02 -040069 struct lock_manager *lm;
Jeff Laytonf7790022014-09-12 16:40:20 -040070
J. Bruce Fieldsc87fb4a2015-08-06 12:47:02 -040071 if (!open)
72 return !list_empty(grace_list);
73
74 list_for_each_entry(lm, grace_list, list) {
75 if (lm->block_opens)
76 return true;
77 }
78 return false;
79}
80
81int locks_in_grace(struct net *net)
82{
83 return __state_in_grace(net, 0);
Jeff Laytonf7790022014-09-12 16:40:20 -040084}
85EXPORT_SYMBOL_GPL(locks_in_grace);
86
J. Bruce Fieldsc87fb4a2015-08-06 12:47:02 -040087int opens_in_grace(struct net *net)
88{
89 return __state_in_grace(net, 1);
90}
91EXPORT_SYMBOL_GPL(opens_in_grace);
92
Jeff Laytonf7790022014-09-12 16:40:20 -040093static int __net_init
94grace_init_net(struct net *net)
95{
96 struct list_head *grace_list = net_generic(net, grace_net_id);
97
98 INIT_LIST_HEAD(grace_list);
99 return 0;
100}
101
102static void __net_exit
103grace_exit_net(struct net *net)
104{
105 struct list_head *grace_list = net_generic(net, grace_net_id);
106
107 BUG_ON(!list_empty(grace_list));
108}
109
110static struct pernet_operations grace_net_ops = {
111 .init = grace_init_net,
112 .exit = grace_exit_net,
113 .id = &grace_net_id,
114 .size = sizeof(struct list_head),
115};
116
117static int __init
118init_grace(void)
119{
120 return register_pernet_subsys(&grace_net_ops);
121}
122
123static void __exit
124exit_grace(void)
125{
126 unregister_pernet_subsys(&grace_net_ops);
127}
128
129MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>");
130MODULE_LICENSE("GPL");
131module_init(init_grace)
132module_exit(exit_grace)