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| 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 | */ |
| 22 | void 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 | */ |
| 40 | void 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 | */ |
| 55 | int locks_in_grace(void) |
| 56 | { |
| 57 | return !list_empty(&grace_list); |
| 58 | } |
| 59 | EXPORT_SYMBOL_GPL(locks_in_grace); |
| 60 |
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