2 * Common code for control of lockd and nfsv4 grace periods.
4 * Transplanted from lockd code
7 #include <linux/module.h>
8 #include <net/net_namespace.h>
9 #include <net/netns/generic.h>
12 static int grace_net_id;
13 static DEFINE_SPINLOCK(grace_lock);
17 * @net: net namespace that this lock manager belongs to
18 * @lm: who this grace period is for
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.
25 * This function is called to start a grace period.
28 locks_start_grace(struct net *net, struct lock_manager *lm)
30 struct list_head *grace_list = net_generic(net, grace_net_id);
32 spin_lock(&grace_lock);
33 list_add(&lm->list, grace_list);
34 spin_unlock(&grace_lock);
36 EXPORT_SYMBOL_GPL(locks_start_grace);
40 * @net: net namespace that this lock manager belongs to
41 * @lm: who this grace period is for
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.
50 locks_end_grace(struct lock_manager *lm)
52 spin_lock(&grace_lock);
53 list_del_init(&lm->list);
54 spin_unlock(&grace_lock);
56 EXPORT_SYMBOL_GPL(locks_end_grace);
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
66 locks_in_grace(struct net *net)
68 struct list_head *grace_list = net_generic(net, grace_net_id);
70 return !list_empty(grace_list);
72 EXPORT_SYMBOL_GPL(locks_in_grace);
75 grace_init_net(struct net *net)
77 struct list_head *grace_list = net_generic(net, grace_net_id);
79 INIT_LIST_HEAD(grace_list);
83 static void __net_exit
84 grace_exit_net(struct net *net)
86 struct list_head *grace_list = net_generic(net, grace_net_id);
88 BUG_ON(!list_empty(grace_list));
91 static struct pernet_operations grace_net_ops = {
92 .init = grace_init_net,
93 .exit = grace_exit_net,
95 .size = sizeof(struct list_head),
101 return register_pernet_subsys(&grace_net_ops);
107 unregister_pernet_subsys(&grace_net_ops);
110 MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>");
111 MODULE_LICENSE("GPL");
112 module_init(init_grace)
113 module_exit(exit_grace)