GNU Linux-libre 4.9.308-gnu1
[releases.git] / fs / dlm / ast.c
1 /******************************************************************************
2 *******************************************************************************
3 **
4 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
5 **  Copyright (C) 2004-2010 Red Hat, Inc.  All rights reserved.
6 **
7 **  This copyrighted material is made available to anyone wishing to use,
8 **  modify, copy, or redistribute it subject to the terms and conditions
9 **  of the GNU General Public License v.2.
10 **
11 *******************************************************************************
12 ******************************************************************************/
13
14 #include "dlm_internal.h"
15 #include "lock.h"
16 #include "user.h"
17 #include "ast.h"
18
19 static uint64_t dlm_cb_seq;
20 static DEFINE_SPINLOCK(dlm_cb_seq_spin);
21
22 static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
23 {
24         int i;
25
26         log_print("last_bast %x %llu flags %x mode %d sb %d %x",
27                   lkb->lkb_id,
28                   (unsigned long long)lkb->lkb_last_bast.seq,
29                   lkb->lkb_last_bast.flags,
30                   lkb->lkb_last_bast.mode,
31                   lkb->lkb_last_bast.sb_status,
32                   lkb->lkb_last_bast.sb_flags);
33
34         log_print("last_cast %x %llu flags %x mode %d sb %d %x",
35                   lkb->lkb_id,
36                   (unsigned long long)lkb->lkb_last_cast.seq,
37                   lkb->lkb_last_cast.flags,
38                   lkb->lkb_last_cast.mode,
39                   lkb->lkb_last_cast.sb_status,
40                   lkb->lkb_last_cast.sb_flags);
41
42         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
43                 log_print("cb %x %llu flags %x mode %d sb %d %x",
44                           lkb->lkb_id,
45                           (unsigned long long)lkb->lkb_callbacks[i].seq,
46                           lkb->lkb_callbacks[i].flags,
47                           lkb->lkb_callbacks[i].mode,
48                           lkb->lkb_callbacks[i].sb_status,
49                           lkb->lkb_callbacks[i].sb_flags);
50         }
51 }
52
53 int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
54                          int status, uint32_t sbflags, uint64_t seq)
55 {
56         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
57         uint64_t prev_seq;
58         int prev_mode;
59         int i, rv;
60
61         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
62                 if (lkb->lkb_callbacks[i].seq)
63                         continue;
64
65                 /*
66                  * Suppress some redundant basts here, do more on removal.
67                  * Don't even add a bast if the callback just before it
68                  * is a bast for the same mode or a more restrictive mode.
69                  * (the addional > PR check is needed for PR/CW inversion)
70                  */
71
72                 if ((i > 0) && (flags & DLM_CB_BAST) &&
73                     (lkb->lkb_callbacks[i-1].flags & DLM_CB_BAST)) {
74
75                         prev_seq = lkb->lkb_callbacks[i-1].seq;
76                         prev_mode = lkb->lkb_callbacks[i-1].mode;
77
78                         if ((prev_mode == mode) ||
79                             (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {
80
81                                 log_debug(ls, "skip %x add bast %llu mode %d "
82                                           "for bast %llu mode %d",
83                                           lkb->lkb_id,
84                                           (unsigned long long)seq,
85                                           mode,
86                                           (unsigned long long)prev_seq,
87                                           prev_mode);
88                                 rv = 0;
89                                 goto out;
90                         }
91                 }
92
93                 lkb->lkb_callbacks[i].seq = seq;
94                 lkb->lkb_callbacks[i].flags = flags;
95                 lkb->lkb_callbacks[i].mode = mode;
96                 lkb->lkb_callbacks[i].sb_status = status;
97                 lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
98                 rv = 0;
99                 break;
100         }
101
102         if (i == DLM_CALLBACKS_SIZE) {
103                 log_error(ls, "no callbacks %x %llu flags %x mode %d sb %d %x",
104                           lkb->lkb_id, (unsigned long long)seq,
105                           flags, mode, status, sbflags);
106                 dlm_dump_lkb_callbacks(lkb);
107                 rv = -1;
108                 goto out;
109         }
110  out:
111         return rv;
112 }
113
114 int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
115                          struct dlm_callback *cb, int *resid)
116 {
117         int i, rv;
118
119         *resid = 0;
120
121         if (!lkb->lkb_callbacks[0].seq) {
122                 rv = -ENOENT;
123                 goto out;
124         }
125
126         /* oldest undelivered cb is callbacks[0] */
127
128         memcpy(cb, &lkb->lkb_callbacks[0], sizeof(struct dlm_callback));
129         memset(&lkb->lkb_callbacks[0], 0, sizeof(struct dlm_callback));
130
131         /* shift others down */
132
133         for (i = 1; i < DLM_CALLBACKS_SIZE; i++) {
134                 if (!lkb->lkb_callbacks[i].seq)
135                         break;
136                 memcpy(&lkb->lkb_callbacks[i-1], &lkb->lkb_callbacks[i],
137                        sizeof(struct dlm_callback));
138                 memset(&lkb->lkb_callbacks[i], 0, sizeof(struct dlm_callback));
139                 (*resid)++;
140         }
141
142         /* if cb is a bast, it should be skipped if the blocking mode is
143            compatible with the last granted mode */
144
145         if ((cb->flags & DLM_CB_BAST) && lkb->lkb_last_cast.seq) {
146                 if (dlm_modes_compat(cb->mode, lkb->lkb_last_cast.mode)) {
147                         cb->flags |= DLM_CB_SKIP;
148
149                         log_debug(ls, "skip %x bast %llu mode %d "
150                                   "for cast %llu mode %d",
151                                   lkb->lkb_id,
152                                   (unsigned long long)cb->seq,
153                                   cb->mode,
154                                   (unsigned long long)lkb->lkb_last_cast.seq,
155                                   lkb->lkb_last_cast.mode);
156                         rv = 0;
157                         goto out;
158                 }
159         }
160
161         if (cb->flags & DLM_CB_CAST) {
162                 memcpy(&lkb->lkb_last_cast, cb, sizeof(struct dlm_callback));
163                 lkb->lkb_last_cast_time = ktime_get();
164         }
165
166         if (cb->flags & DLM_CB_BAST) {
167                 memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
168                 lkb->lkb_last_bast_time = ktime_get();
169         }
170         rv = 0;
171  out:
172         return rv;
173 }
174
175 void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
176                 uint32_t sbflags)
177 {
178         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
179         uint64_t new_seq, prev_seq;
180         int rv;
181
182         spin_lock(&dlm_cb_seq_spin);
183         new_seq = ++dlm_cb_seq;
184         spin_unlock(&dlm_cb_seq_spin);
185
186         if (lkb->lkb_flags & DLM_IFL_USER) {
187                 dlm_user_add_ast(lkb, flags, mode, status, sbflags, new_seq);
188                 return;
189         }
190
191         mutex_lock(&lkb->lkb_cb_mutex);
192         prev_seq = lkb->lkb_callbacks[0].seq;
193
194         rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, new_seq);
195         if (rv < 0)
196                 goto out;
197
198         if (!prev_seq) {
199                 kref_get(&lkb->lkb_ref);
200
201                 if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
202                         mutex_lock(&ls->ls_cb_mutex);
203                         list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
204                         mutex_unlock(&ls->ls_cb_mutex);
205                 } else {
206                         queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
207                 }
208         }
209  out:
210         mutex_unlock(&lkb->lkb_cb_mutex);
211 }
212
213 void dlm_callback_work(struct work_struct *work)
214 {
215         struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
216         struct dlm_ls *ls = lkb->lkb_resource->res_ls;
217         void (*castfn) (void *astparam);
218         void (*bastfn) (void *astparam, int mode);
219         struct dlm_callback callbacks[DLM_CALLBACKS_SIZE];
220         int i, rv, resid;
221
222         memset(&callbacks, 0, sizeof(callbacks));
223
224         mutex_lock(&lkb->lkb_cb_mutex);
225         if (!lkb->lkb_callbacks[0].seq) {
226                 /* no callback work exists, shouldn't happen */
227                 log_error(ls, "dlm_callback_work %x no work", lkb->lkb_id);
228                 dlm_print_lkb(lkb);
229                 dlm_dump_lkb_callbacks(lkb);
230         }
231
232         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
233                 rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
234                 if (rv < 0)
235                         break;
236         }
237
238         if (resid) {
239                 /* cbs remain, loop should have removed all, shouldn't happen */
240                 log_error(ls, "dlm_callback_work %x resid %d", lkb->lkb_id,
241                           resid);
242                 dlm_print_lkb(lkb);
243                 dlm_dump_lkb_callbacks(lkb);
244         }
245         mutex_unlock(&lkb->lkb_cb_mutex);
246
247         castfn = lkb->lkb_astfn;
248         bastfn = lkb->lkb_bastfn;
249
250         for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
251                 if (!callbacks[i].seq)
252                         break;
253                 if (callbacks[i].flags & DLM_CB_SKIP) {
254                         continue;
255                 } else if (callbacks[i].flags & DLM_CB_BAST) {
256                         bastfn(lkb->lkb_astparam, callbacks[i].mode);
257                 } else if (callbacks[i].flags & DLM_CB_CAST) {
258                         lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
259                         lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
260                         castfn(lkb->lkb_astparam);
261                 }
262         }
263
264         /* undo kref_get from dlm_add_callback, may cause lkb to be freed */
265         dlm_put_lkb(lkb);
266 }
267
268 int dlm_callback_start(struct dlm_ls *ls)
269 {
270         ls->ls_callback_wq = alloc_workqueue("dlm_callback",
271                                              WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
272         if (!ls->ls_callback_wq) {
273                 log_print("can't start dlm_callback workqueue");
274                 return -ENOMEM;
275         }
276         return 0;
277 }
278
279 void dlm_callback_stop(struct dlm_ls *ls)
280 {
281         if (ls->ls_callback_wq)
282                 destroy_workqueue(ls->ls_callback_wq);
283 }
284
285 void dlm_callback_suspend(struct dlm_ls *ls)
286 {
287         set_bit(LSFL_CB_DELAY, &ls->ls_flags);
288
289         if (ls->ls_callback_wq)
290                 flush_workqueue(ls->ls_callback_wq);
291 }
292
293 #define MAX_CB_QUEUE 25
294
295 void dlm_callback_resume(struct dlm_ls *ls)
296 {
297         struct dlm_lkb *lkb, *safe;
298         int count = 0;
299
300         clear_bit(LSFL_CB_DELAY, &ls->ls_flags);
301
302         if (!ls->ls_callback_wq)
303                 return;
304
305 more:
306         mutex_lock(&ls->ls_cb_mutex);
307         list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
308                 list_del_init(&lkb->lkb_cb_list);
309                 queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
310                 count++;
311                 if (count == MAX_CB_QUEUE)
312                         break;
313         }
314         mutex_unlock(&ls->ls_cb_mutex);
315
316         if (count)
317                 log_rinfo(ls, "dlm_callback_resume %d", count);
318         if (count == MAX_CB_QUEUE) {
319                 count = 0;
320                 cond_resched();
321                 goto more;
322         }
323 }
324