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