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 __state_in_grace(struct net *net, bool open) 67 { 68 struct list_head *grace_list = net_generic(net, grace_net_id); 69 struct lock_manager *lm; 70 71 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 81 int locks_in_grace(struct net *net) 82 { 83 return __state_in_grace(net, 0); 84 } 85 EXPORT_SYMBOL_GPL(locks_in_grace); 86 87 int opens_in_grace(struct net *net) 88 { 89 return __state_in_grace(net, 1); 90 } 91 EXPORT_SYMBOL_GPL(opens_in_grace); 92 93 static int __net_init 94 grace_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 } 101 102 static void __net_exit 103 grace_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 } 109 110 static 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 }; 116 117 static int __init 118 init_grace(void) 119 { 120 return register_pernet_subsys(&grace_net_ops); 121 } 122 123 static void __exit 124 exit_grace(void) 125 { 126 unregister_pernet_subsys(&grace_net_ops); 127 } 128 129 MODULE_AUTHOR("Jeff Layton <jlayton@primarydata.com>"); 130 MODULE_LICENSE("GPL"); 131 module_init(init_grace) 132 module_exit(exit_grace) 133