aboutsummaryrefslogtreecommitdiffstats
path: root/fs/dlm/ast.c
blob: abc49f292454afa387d42a9be4b5437c2ad3f46d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

#include "dlm_internal.h"
#include "lock.h"
#include "user.h"
#include "ast.h"

#define WAKE_ASTS  0

static uint64_t			ast_seq_count;
static struct list_head		ast_queue;
static spinlock_t		ast_queue_lock;
static struct task_struct *	astd_task;
static unsigned long		astd_wakeflags;
static struct mutex		astd_running;


static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
{
	int i;

	log_print("last_bast %x %llu flags %x mode %d sb %d %x",
		  lkb->lkb_id,
		  (unsigned long long)lkb->lkb_last_bast.seq,
		  lkb->lkb_last_bast.flags,
		  lkb->lkb_last_bast.mode,
		  lkb->lkb_last_bast.sb_status,
		  lkb->lkb_last_bast.sb_flags);

	log_print("last_cast %x %llu flags %x mode %d sb %d %x",
		  lkb->lkb_id,
		  (unsigned long long)lkb->lkb_last_cast.seq,
		  lkb->lkb_last_cast.flags,
		  lkb->lkb_last_cast.mode,
		  lkb->lkb_last_cast.sb_status,
		  lkb->lkb_last_cast.sb_flags);

	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
		log_print("cb %x %llu flags %x mode %d sb %d %x",
			  lkb->lkb_id,
			  (unsigned long long)lkb->lkb_callbacks[i].seq,
			  lkb->lkb_callbacks[i].flags,
			  lkb->lkb_callbacks[i].mode,
			  lkb->lkb_callbacks[i].sb_status,
			  lkb->lkb_callbacks[i].sb_flags);
	}
}

void dlm_del_ast(struct dlm_lkb *lkb)
{
	spin_lock(&ast_queue_lock);
	if (!list_empty(&lkb->lkb_astqueue))
		list_del_init(&lkb->lkb_astqueue);
	spin_unlock(&ast_queue_lock);
}

int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
			 int status, uint32_t sbflags, uint64_t seq)
{
	struct dlm_ls *ls = lkb->lkb_resource->res_ls;
	uint64_t prev_seq;
	int prev_mode;
	int i;

	for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
		if (lkb->lkb_callbacks[i].seq)
			continue;

		/*
		 * Suppress some redundant basts here, do more on removal.
		 * Don't even add a bast if the callback just before it
		 * is a bast for the same mode or a more restrictive mode.
		 * (the addional > PR check is needed for PR/CW inversion)
		 */

		if ((i > 0) && (flags & DLM_CB_BAST) &&
		    (lkb->lkb_callbacks[i-1].flags & DLM_CB_BAST)) {

			prev_seq = lkb->lkb_callbacks[i-1].seq;
			prev_mode = lkb->lkb_callbacks[i-1].mode;

			if ((prev_mode == mode) ||
			    (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {

				log_debug(ls, "skip %x add bast %llu mode %d "
					  "for bast %llu mode %d",
					  lkb->lkb_id,
					  (unsigned long long)seq,
					  mode,
					  (unsigned long long)prev_seq,
					  prev_mode);
				return 0;
			}
		}

		lkb->lkb_callbacks[i].seq = seq;
		lkb->lkb_callbacks[i].flags = flags;
		lkb->lkb_callbacks[i].mode = mode;
		lkb->lkb_callbacks[i].sb_status = status;
		lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
		break;
	}

	if (i == DLM_CALLBACKS_SIZE) {
		log_error(ls, "no callbacks %x %llu flags %x mode %d sb %d %x",
			  lkb->lkb_id, (unsigned long long)seq,
			  flags, mode, status, sbflags);
		dlm_dump_lkb_callbacks(lkb);
		return -1;
	}

	return 0;
}

int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
			 struct dlm_callback *cb, int *resid)
{
	int i;

	*resid = 0;

	if (!lkb->lkb_callbacks[0].seq)
		return -ENOENT;

	/* oldest undelivered cb is callbacks[0] */

	memcpy(cb, &lkb->lkb_callbacks[0], sizeof(struct dlm_callback));
	memset(&lkb->lkb_callbacks[0], 0, sizeof(struct dlm_callback));

	/* shift others down */

	for (i = 1; i < DLM_CALLBACKS_SIZE; i++) {
		if (!lkb->lkb_callbacks[i].seq)
			break;
		memcpy(&lkb->lkb_callbacks[i-1], &lkb->lkb_callbacks[i],
		       sizeof(struct dlm_callback));
		memset(&lkb->lkb_callbacks[i], 0, sizeof(struct dlm_callback));
		(*resid)++;
	}

	/* if cb is a bast, it should be skipped if the blocking mode is
	   compatible with the last granted mode */

	if ((cb->flags & DLM_CB_BAST) && lkb->lkb_last_cast.seq) {
		if (dlm_modes_compat(cb->mode, lkb->lkb_last_cast.mode)) {
			cb->flags |= DLM_CB_SKIP;

			log_debug(ls, "skip %x bast %llu mode %d "
				  "for cast %llu mode %d",
				  lkb->lkb_id,
				  (unsigned long long)cb->seq,
				  cb->mode,
				  (unsigned long long)lkb->lkb_last_cast.seq,
				  lkb->lkb_last_cast.mode);
			return 0;
		}
	}

	if (cb->flags & DLM_CB_CAST) {
		memcpy(&lkb->lkb_last_cast, cb, sizeof(struct dlm_callback));
		lkb->lkb_last_cast_time = ktime_get();
	}

	if (cb->flags & DLM_CB_BAST) {
		memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
		lkb->lkb_last_bast_time = ktime_get();
	}

	return 0;
}

void dlm_add_ast(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
		 uint32_t sbflags)
{
	uint64_t seq;
	int rv;

	spin_lock(&ast_queue_lock);

	seq = ++ast_seq_count;

	if (lkb->lkb_flags & DLM_IFL_USER) {
		spin_unlock(&ast_queue_lock);
		dlm_user_add_ast(lkb, flags, mode, status, sbflags, seq);
		return;
	}

	rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, seq);
	if (rv < 0) {
		spin_unlock(&ast_queue_lock);
		return;
	}

	if (list_empty(&lkb->lkb_astqueue)) {
		kref_get(&lkb->lkb_ref);
		list_add_tail(&lkb->lkb_astqueue, &ast_queue);
	}
	spin_unlock(&ast_queue_lock);

	set_bit(WAKE_ASTS, &astd_wakeflags);
	wake_up_process(astd_task);
}

static void process_asts(void)
{
	struct dlm_ls *ls = NULL;
	struct dlm_rsb *r = NULL;
	struct dlm_lkb *lkb;
	void (*castfn) (void *astparam);
	void (*bastfn) (void *astparam, int mode);
	struct dlm_callback callbacks[DLM_CALLBACKS_SIZE];
	int i, rv, resid;

repeat:
	spin_lock(&ast_queue_lock);
	list_for_each_entry(lkb, &ast_queue, lkb_astqueue) {
		r = lkb->lkb_resource;
		ls = r->res_ls;

		if (dlm_locking_stopped(ls))
			continue;

		/* we remove from astqueue list and remove everything in
		   lkb_callbacks before releasing the spinlock so empty
		   lkb_astqueue is always consistent with empty lkb_callbacks */

		list_del_init(&lkb->lkb_astqueue);

		castfn = lkb->lkb_astfn;
		bastfn = lkb->lkb_bastfn;

		memset(&callbacks, 0, sizeof(callbacks));

		for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
			rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
			if (rv < 0)
				break;
		}
		spin_unlock(&ast_queue_lock);

		if (resid) {
			/* shouldn't happen, for loop should have removed all */
			log_error(ls, "callback resid %d lkb %x",
				  resid, lkb->lkb_id);
		}

		for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
			if (!callbacks[i].seq)
				break;
			if (callbacks[i].flags & DLM_CB_SKIP) {
				continue;
			} else if (callbacks[i].flags & DLM_CB_BAST) {
				bastfn(lkb->lkb_astparam, callbacks[i].mode);
			} else if (callbacks[i].flags & DLM_CB_CAST) {
				lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
				lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
				castfn(lkb->lkb_astparam);
			}
		}

		/* removes ref for ast_queue, may cause lkb to be freed */
		dlm_put_lkb(lkb);

		cond_resched();
		goto repeat;
	}
	spin_unlock(&ast_queue_lock);
}

static inline int no_asts(void)
{
	int ret;

	spin_lock(&ast_queue_lock);
	ret = list_empty(&ast_queue);
	spin_unlock(&ast_queue_lock);
	return ret;
}

static int dlm_astd(void *data)
{
	while (!kthread_should_stop()) {
		set_current_state(TASK_INTERRUPTIBLE);
		if (!test_bit(WAKE_ASTS, &astd_wakeflags))
			schedule();
		set_current_state(TASK_RUNNING);

		mutex_lock(&astd_running);
		if (test_and_clear_bit(WAKE_ASTS, &astd_wakeflags))
			process_asts();
		mutex_unlock(&astd_running);
	}
	return 0;
}

void dlm_astd_wake(void)
{
	if (!no_asts()) {
		set_bit(WAKE_ASTS, &astd_wakeflags);
		wake_up_process(astd_task);
	}
}

int dlm_astd_start(void)
{
	struct task_struct *p;
	int error = 0;

	INIT_LIST_HEAD(&ast_queue);
	spin_lock_init(&ast_queue_lock);
	mutex_init(&astd_running);

	p = kthread_run(dlm_astd, NULL, "dlm_astd");
	if (IS_ERR(p))
		error = PTR_ERR(p);
	else
		astd_task = p;
	return error;
}

void dlm_astd_stop(void)
{
	kthread_stop(astd_task);
}

void dlm_astd_suspend(void)
{
	mutex_lock(&astd_running);
}

void dlm_astd_resume(void)
{
	mutex_unlock(&astd_running);
}