| Jeff Layton | f779002 | 2014-09-12 16:40:20 -0400 | [diff] [blame] | 1 | /* |
| 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 | |
| 12 | static int grace_net_id; |
| 13 | static 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 | */ |
| 27 | void |
| 28 | locks_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 | } |
| 36 | EXPORT_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 | */ |
| 49 | void |
| 50 | locks_end_grace(struct lock_manager *lm) |
| 51 | { |
| 52 | spin_lock(&grace_lock); |
| 53 | list_del_init(&lm->list); |
| 54 | spin_unlock(&grace_lock); |
| 55 | } |
| 56 | EXPORT_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 | */ |
| 65 | int |
| 66 | locks_in_grace(struct net *net) |
| 67 | { |
| 68 | struct list_head *grace_list = net_generic(net, grace_net_id); |
| 69 | |
| 70 | return !list_empty(grace_list); |
| 71 | } |
| 72 | EXPORT_SYMBOL_GPL(locks_in_grace); |
| 73 | |
| 74 | static int __net_init |
| 75 | grace_init_net(struct net *net) |
| 76 | { |
| 77 | struct list_head *grace_list = net_generic(net, grace_net_id); |
| 78 | |
| 79 | INIT_LIST_HEAD(grace_list); |
| 80 | return 0; |
| 81 | } |
| 82 | |
| 83 | static void __net_exit |
| 84 | grace_exit_net(struct net *net) |
| 85 | { |
| 86 | struct list_head *grace_list = net_generic(net, grace_net_id); |
| 87 | |
| 88 | BUG_ON(!list_empty(grace_list)); |
| 89 | } |
| 90 | |
| 91 | static struct pernet_operations grace_net_ops = { |
| 92 | .init = grace_init_net, |
| 93 | .exit = grace_exit_net, |
| 94 | .id = &grace_net_id, |
| 95 | .size = sizeof(struct list_head), |
| 96 | }; |
| 97 | |
| 98 | static int __init |
| 99 | init_grace(void) |
| 100 | { |
| 101 | return register_pernet_subsys(&grace_net_ops); |
| 102 | } |
| 103 | |
| 104 | static void __exit |
| 105 | exit_grace(void) |
| 106 | { |
| 107 | unregister_pernet_subsys(&grace_net_ops); |
| 108 | } |
| 109 | |
| 110 | MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>"); |
| 111 | MODULE_LICENSE("GPL"); |
| 112 | module_init(init_grace) |
| 113 | module_exit(exit_grace) |