md/persistent-data/dm-block-manager.c

32  * trace is also emitted for the previous lock acquisition.
45 	spinlock_t lock;
61 static unsigned int __find_holder(struct block_lock *lock,
67 		if (lock->holders[i] == task)
74 /* call this *after* you increment lock->count */
75 static void __add_holder(struct block_lock *lock, struct task_struct *task)
77 	unsigned int h = __find_holder(lock, NULL);
83 	lock->holders[h] = task;
86 	t = lock->traces + h;
91 /* call this *before* you decrement lock->count */
92 static void __del_holder(struct block_lock *lock, struct task_struct *task)
94 	unsigned int h = __find_holder(lock, task);
96 	lock->holders[h] = NULL;
100 static int __check_holder(struct block_lock *lock)
105 		if (lock->holders[i] == current) {
106 			DMERR("recursive lock detected in metadata");
109 			stack_trace_print(lock->traces[i].entries,
110 					  lock->traces[i].nr_entries, 4);
150 static void __wake_many(struct block_lock *lock)
154 	BUG_ON(lock->count < 0);
155 	list_for_each_entry_safe(w, tmp, &lock->waiters, list) {
156 		if (lock->count >= MAX_HOLDERS)
160 			if (lock->count > 0)
163 			lock->count = -1;
164 			__add_holder(lock, w->task);
169 		lock->count++;
170 		__add_holder(lock, w->task);
175 static void bl_init(struct block_lock *lock)
179 	spin_lock_init(&lock->lock);
180 	lock->count = 0;
181 	INIT_LIST_HEAD(&lock->waiters);
183 		lock->holders[i] = NULL;
186 static int __available_for_read(struct block_lock *lock)
188 	return lock->count >= 0 &&
189 		lock->count < MAX_HOLDERS &&
190 		list_empty(&lock->waiters);
193 static int bl_down_read(struct block_lock *lock)
198 	spin_lock(&lock->lock);
199 	r = __check_holder(lock);
201 		spin_unlock(&lock->lock);
205 	if (__available_for_read(lock)) {
206 		lock->count++;
207 		__add_holder(lock, current);
208 		spin_unlock(&lock->lock);
216 	list_add_tail(&w.list, &lock->waiters);
217 	spin_unlock(&lock->lock);
224 static int bl_down_read_nonblock(struct block_lock *lock)
228 	spin_lock(&lock->lock);
229 	r = __check_holder(lock);
233 	if (__available_for_read(lock)) {
234 		lock->count++;
235 		__add_holder(lock, current);
241 	spin_unlock(&lock->lock);
245 static void bl_up_read(struct block_lock *lock)
247 	spin_lock(&lock->lock);
248 	BUG_ON(lock->count <= 0);
249 	__del_holder(lock, current);
250 	--lock->count;
251 	if (!list_empty(&lock->waiters))
252 		__wake_many(lock);
253 	spin_unlock(&lock->lock);
256 static int bl_down_write(struct block_lock *lock)
261 	spin_lock(&lock->lock);
262 	r = __check_holder(lock);
264 		spin_unlock(&lock->lock);
268 	if (lock->count == 0 && list_empty(&lock->waiters)) {
269 		lock->count = -1;
270 		__add_holder(lock, current);
271 		spin_unlock(&lock->lock);
283 	list_add(&w.list, &lock->waiters);
284 	spin_unlock(&lock->lock);
292 static void bl_up_write(struct block_lock *lock)
294 	spin_lock(&lock->lock);
295 	__del_holder(lock, current);
296 	lock->count = 0;
297 	if (!list_empty(&lock->waiters))
298 		__wake_many(lock);
299 	spin_unlock(&lock->lock);
352 	struct block_lock lock;
361 	bl_init(&aux->lock);
482 	r = bl_down_read(&aux->lock);
493 		bl_up_read(&aux->lock);
518 	r = bl_down_write(&aux->lock);
529 		bl_up_write(&aux->lock);
553 	r = bl_down_read_nonblock(&aux->lock);
563 		bl_up_read(&aux->lock);
589 	r = bl_down_write(&aux->lock);
608 		bl_up_write(&aux->lock);
610 		bl_up_read(&aux->lock);