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af558e33 BF |
1 | /* |
2 | * Common code for control of lockd and nfsv4 grace periods. | |
3 | */ | |
4 | ||
5 | #include <linux/module.h> | |
6 | #include <linux/lockd/bind.h> | |
db9c4553 SK |
7 | #include <net/net_namespace.h> |
8 | ||
9 | #include "netns.h" | |
af558e33 | 10 | |
af558e33 BF |
11 | static DEFINE_SPINLOCK(grace_lock); |
12 | ||
13 | /** | |
14 | * locks_start_grace | |
15 | * @lm: who this grace period is for | |
16 | * | |
17 | * A grace period is a period during which locks should not be given | |
18 | * out. Currently grace periods are only enforced by the two lock | |
19 | * managers (lockd and nfsd), using the locks_in_grace() function to | |
20 | * check when they are in a grace period. | |
21 | * | |
22 | * This function is called to start a grace period. | |
23 | */ | |
24 | void locks_start_grace(struct lock_manager *lm) | |
25 | { | |
db9c4553 SK |
26 | struct net *net = &init_net; |
27 | struct lockd_net *ln = net_generic(net, lockd_net_id); | |
28 | ||
af558e33 | 29 | spin_lock(&grace_lock); |
db9c4553 | 30 | list_add(&lm->list, &ln->grace_list); |
af558e33 BF |
31 | spin_unlock(&grace_lock); |
32 | } | |
33 | EXPORT_SYMBOL_GPL(locks_start_grace); | |
34 | ||
35 | /** | |
36 | * locks_end_grace | |
37 | * @lm: who this grace period is for | |
38 | * | |
39 | * Call this function to state that the given lock manager is ready to | |
40 | * resume regular locking. The grace period will not end until all lock | |
41 | * managers that called locks_start_grace() also call locks_end_grace(). | |
42 | * Note that callers count on it being safe to call this more than once, | |
43 | * and the second call should be a no-op. | |
44 | */ | |
45 | void locks_end_grace(struct lock_manager *lm) | |
46 | { | |
47 | spin_lock(&grace_lock); | |
48 | list_del_init(&lm->list); | |
49 | spin_unlock(&grace_lock); | |
50 | } | |
51 | EXPORT_SYMBOL_GPL(locks_end_grace); | |
52 | ||
53 | /** | |
54 | * locks_in_grace | |
55 | * | |
56 | * Lock managers call this function to determine when it is OK for them | |
57 | * to answer ordinary lock requests, and when they should accept only | |
58 | * lock reclaims. | |
59 | */ | |
60 | int locks_in_grace(void) | |
61 | { | |
db9c4553 SK |
62 | struct net *net = &init_net; |
63 | struct lockd_net *ln = net_generic(net, lockd_net_id); | |
64 | ||
65 | return !list_empty(&ln->grace_list); | |
af558e33 BF |
66 | } |
67 | EXPORT_SYMBOL_GPL(locks_in_grace); |