ocfs2: add fsdlm to stackglue
[linux-3.10.git] / fs / ocfs2 / stackglue.c
1 /* -*- mode: c; c-basic-offset: 8; -*-
2  * vim: noexpandtab sw=8 ts=8 sts=0:
3  *
4  * stackglue.c
5  *
6  * Code which implements an OCFS2 specific interface to underlying
7  * cluster stacks.
8  *
9  * Copyright (C) 2007 Oracle.  All rights reserved.
10  *
11  * This program is free software; you can redistribute it and/or
12  * modify it under the terms of the GNU General Public
13  * License as published by the Free Software Foundation, version 2.
14  *
15  * This program is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  */
20
21 #include <linux/list.h>
22 #include <linux/spinlock.h>
23 #include <linux/module.h>
24 #include <linux/slab.h>
25 #include <linux/kmod.h>
26 #include <linux/fs.h>
27 #include <linux/kobject.h>
28 #include <linux/sysfs.h>
29
30 #include "ocfs2_fs.h"
31
32 #include "stackglue.h"
33
34 #define OCFS2_STACK_PLUGIN_O2CB         "o2cb"
35 #define OCFS2_STACK_PLUGIN_USER         "user"
36
37 static struct ocfs2_locking_protocol *lproto;
38 static DEFINE_SPINLOCK(ocfs2_stack_lock);
39 static LIST_HEAD(ocfs2_stack_list);
40 static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
41
42 /*
43  * The stack currently in use.  If not null, active_stack->sp_count > 0,
44  * the module is pinned, and the locking protocol cannot be changed.
45  */
46 static struct ocfs2_stack_plugin *active_stack;
47
48 static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
49 {
50         struct ocfs2_stack_plugin *p;
51
52         assert_spin_locked(&ocfs2_stack_lock);
53
54         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
55                 if (!strcmp(p->sp_name, name))
56                         return p;
57         }
58
59         return NULL;
60 }
61
62 static int ocfs2_stack_driver_request(const char *stack_name,
63                                       const char *plugin_name)
64 {
65         int rc;
66         struct ocfs2_stack_plugin *p;
67
68         spin_lock(&ocfs2_stack_lock);
69
70         /*
71          * If the stack passed by the filesystem isn't the selected one,
72          * we can't continue.
73          */
74         if (strcmp(stack_name, cluster_stack_name)) {
75                 rc = -EBUSY;
76                 goto out;
77         }
78
79         if (active_stack) {
80                 /*
81                  * If the active stack isn't the one we want, it cannot
82                  * be selected right now.
83                  */
84                 if (!strcmp(active_stack->sp_name, plugin_name))
85                         rc = 0;
86                 else
87                         rc = -EBUSY;
88                 goto out;
89         }
90
91         p = ocfs2_stack_lookup(plugin_name);
92         if (!p || !try_module_get(p->sp_owner)) {
93                 rc = -ENOENT;
94                 goto out;
95         }
96
97         /* Ok, the stack is pinned */
98         p->sp_count++;
99         active_stack = p;
100
101         rc = 0;
102
103 out:
104         spin_unlock(&ocfs2_stack_lock);
105         return rc;
106 }
107
108 /*
109  * This function looks up the appropriate stack and makes it active.  If
110  * there is no stack, it tries to load it.  It will fail if the stack still
111  * cannot be found.  It will also fail if a different stack is in use.
112  */
113 static int ocfs2_stack_driver_get(const char *stack_name)
114 {
115         int rc;
116         char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
117
118         /*
119          * Classic stack does not pass in a stack name.  This is
120          * compatible with older tools as well.
121          */
122         if (!stack_name || !*stack_name)
123                 stack_name = OCFS2_STACK_PLUGIN_O2CB;
124
125         if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
126                 printk(KERN_ERR
127                        "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
128                        stack_name);
129                 return -EINVAL;
130         }
131
132         /* Anything that isn't the classic stack is a user stack */
133         if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
134                 plugin_name = OCFS2_STACK_PLUGIN_USER;
135
136         rc = ocfs2_stack_driver_request(stack_name, plugin_name);
137         if (rc == -ENOENT) {
138                 request_module("ocfs2_stack_%s", plugin_name);
139                 rc = ocfs2_stack_driver_request(stack_name, plugin_name);
140         }
141
142         if (rc == -ENOENT) {
143                 printk(KERN_ERR
144                        "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
145                        plugin_name);
146         } else if (rc == -EBUSY) {
147                 printk(KERN_ERR
148                        "ocfs2: A different cluster stack is in use\n");
149         }
150
151         return rc;
152 }
153
154 static void ocfs2_stack_driver_put(void)
155 {
156         spin_lock(&ocfs2_stack_lock);
157         BUG_ON(active_stack == NULL);
158         BUG_ON(active_stack->sp_count == 0);
159
160         active_stack->sp_count--;
161         if (!active_stack->sp_count) {
162                 module_put(active_stack->sp_owner);
163                 active_stack = NULL;
164         }
165         spin_unlock(&ocfs2_stack_lock);
166 }
167
168 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
169 {
170         int rc;
171
172         spin_lock(&ocfs2_stack_lock);
173         if (!ocfs2_stack_lookup(plugin->sp_name)) {
174                 plugin->sp_count = 0;
175                 plugin->sp_proto = lproto;
176                 list_add(&plugin->sp_list, &ocfs2_stack_list);
177                 printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
178                        plugin->sp_name);
179                 rc = 0;
180         } else {
181                 printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
182                        plugin->sp_name);
183                 rc = -EEXIST;
184         }
185         spin_unlock(&ocfs2_stack_lock);
186
187         return rc;
188 }
189 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
190
191 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
192 {
193         struct ocfs2_stack_plugin *p;
194
195         spin_lock(&ocfs2_stack_lock);
196         p = ocfs2_stack_lookup(plugin->sp_name);
197         if (p) {
198                 BUG_ON(p != plugin);
199                 BUG_ON(plugin == active_stack);
200                 BUG_ON(plugin->sp_count != 0);
201                 list_del_init(&plugin->sp_list);
202                 printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
203                        plugin->sp_name);
204         } else {
205                 printk(KERN_ERR "Stack \"%s\" is not registered\n",
206                        plugin->sp_name);
207         }
208         spin_unlock(&ocfs2_stack_lock);
209 }
210 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
211
212 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
213 {
214         struct ocfs2_stack_plugin *p;
215
216         BUG_ON(proto == NULL);
217
218         spin_lock(&ocfs2_stack_lock);
219         BUG_ON(active_stack != NULL);
220
221         lproto = proto;
222         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
223                 p->sp_proto = lproto;
224         }
225
226         spin_unlock(&ocfs2_stack_lock);
227 }
228 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
229
230
231 /*
232  * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
233  * "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
234  * underlying stack plugins need to pilfer the lksb off of the lock_res.
235  * If some other structure needs to be passed as an astarg, the plugins
236  * will need to be given a different avenue to the lksb.
237  */
238 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
239                    int mode,
240                    union ocfs2_dlm_lksb *lksb,
241                    u32 flags,
242                    void *name,
243                    unsigned int namelen,
244                    struct ocfs2_lock_res *astarg)
245 {
246         BUG_ON(lproto == NULL);
247
248         return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
249                                               name, namelen, astarg);
250 }
251 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
252
253 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
254                      union ocfs2_dlm_lksb *lksb,
255                      u32 flags,
256                      struct ocfs2_lock_res *astarg)
257 {
258         BUG_ON(lproto == NULL);
259
260         return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
261 }
262 EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
263
264 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
265 {
266         return active_stack->sp_ops->lock_status(lksb);
267 }
268 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
269
270 /*
271  * Why don't we cast to ocfs2_meta_lvb?  The "clean" answer is that we
272  * don't cast at the glue level.  The real answer is that the header
273  * ordering is nigh impossible.
274  */
275 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
276 {
277         return active_stack->sp_ops->lock_lvb(lksb);
278 }
279 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
280
281 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
282 {
283         active_stack->sp_ops->dump_lksb(lksb);
284 }
285 EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
286
287 int ocfs2_cluster_connect(const char *stack_name,
288                           const char *group,
289                           int grouplen,
290                           void (*recovery_handler)(int node_num,
291                                                    void *recovery_data),
292                           void *recovery_data,
293                           struct ocfs2_cluster_connection **conn)
294 {
295         int rc = 0;
296         struct ocfs2_cluster_connection *new_conn;
297
298         BUG_ON(group == NULL);
299         BUG_ON(conn == NULL);
300         BUG_ON(recovery_handler == NULL);
301
302         if (grouplen > GROUP_NAME_MAX) {
303                 rc = -EINVAL;
304                 goto out;
305         }
306
307         new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
308                            GFP_KERNEL);
309         if (!new_conn) {
310                 rc = -ENOMEM;
311                 goto out;
312         }
313
314         memcpy(new_conn->cc_name, group, grouplen);
315         new_conn->cc_namelen = grouplen;
316         new_conn->cc_recovery_handler = recovery_handler;
317         new_conn->cc_recovery_data = recovery_data;
318
319         /* Start the new connection at our maximum compatibility level */
320         new_conn->cc_version = lproto->lp_max_version;
321
322         /* This will pin the stack driver if successful */
323         rc = ocfs2_stack_driver_get(stack_name);
324         if (rc)
325                 goto out_free;
326
327         rc = active_stack->sp_ops->connect(new_conn);
328         if (rc) {
329                 ocfs2_stack_driver_put();
330                 goto out_free;
331         }
332
333         *conn = new_conn;
334
335 out_free:
336         if (rc)
337                 kfree(new_conn);
338
339 out:
340         return rc;
341 }
342 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
343
344 /* If hangup_pending is 0, the stack driver will be dropped */
345 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
346                              int hangup_pending)
347 {
348         int ret;
349
350         BUG_ON(conn == NULL);
351
352         ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
353
354         /* XXX Should we free it anyway? */
355         if (!ret) {
356                 kfree(conn);
357                 if (!hangup_pending)
358                         ocfs2_stack_driver_put();
359         }
360
361         return ret;
362 }
363 EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
364
365 void ocfs2_cluster_hangup(const char *group, int grouplen)
366 {
367         BUG_ON(group == NULL);
368         BUG_ON(group[grouplen] != '\0');
369
370         if (active_stack->sp_ops->hangup)
371                 active_stack->sp_ops->hangup(group, grouplen);
372
373         /* cluster_disconnect() was called with hangup_pending==1 */
374         ocfs2_stack_driver_put();
375 }
376 EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
377
378 int ocfs2_cluster_this_node(unsigned int *node)
379 {
380         return active_stack->sp_ops->this_node(node);
381 }
382 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
383
384
385 /*
386  * Sysfs bits
387  */
388
389 static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
390                                                struct kobj_attribute *attr,
391                                                char *buf)
392 {
393         ssize_t ret = 0;
394
395         spin_lock(&ocfs2_stack_lock);
396         if (lproto)
397                 ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
398                                lproto->lp_max_version.pv_major,
399                                lproto->lp_max_version.pv_minor);
400         spin_unlock(&ocfs2_stack_lock);
401
402         return ret;
403 }
404
405 static struct kobj_attribute ocfs2_attr_max_locking_protocol =
406         __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
407                ocfs2_max_locking_protocol_show, NULL);
408
409 static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
410                                                  struct kobj_attribute *attr,
411                                                  char *buf)
412 {
413         ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
414         struct ocfs2_stack_plugin *p;
415
416         spin_lock(&ocfs2_stack_lock);
417         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
418                 ret = snprintf(buf, remain, "%s\n",
419                                p->sp_name);
420                 if (ret < 0) {
421                         total = ret;
422                         break;
423                 }
424                 if (ret == remain) {
425                         /* snprintf() didn't fit */
426                         total = -E2BIG;
427                         break;
428                 }
429                 total += ret;
430                 remain -= ret;
431         }
432         spin_unlock(&ocfs2_stack_lock);
433
434         return total;
435 }
436
437 static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
438         __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
439                ocfs2_loaded_cluster_plugins_show, NULL);
440
441 static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
442                                                 struct kobj_attribute *attr,
443                                                 char *buf)
444 {
445         ssize_t ret = 0;
446
447         spin_lock(&ocfs2_stack_lock);
448         if (active_stack) {
449                 ret = snprintf(buf, PAGE_SIZE, "%s\n",
450                                active_stack->sp_name);
451                 if (ret == PAGE_SIZE)
452                         ret = -E2BIG;
453         }
454         spin_unlock(&ocfs2_stack_lock);
455
456         return ret;
457 }
458
459 static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
460         __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
461                ocfs2_active_cluster_plugin_show, NULL);
462
463 static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
464                                         struct kobj_attribute *attr,
465                                         char *buf)
466 {
467         ssize_t ret;
468         spin_lock(&ocfs2_stack_lock);
469         ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
470         spin_unlock(&ocfs2_stack_lock);
471
472         return ret;
473 }
474
475 static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
476                                          struct kobj_attribute *attr,
477                                          const char *buf, size_t count)
478 {
479         size_t len = count;
480         ssize_t ret;
481
482         if (len == 0)
483                 return len;
484
485         if (buf[len - 1] == '\n')
486                 len--;
487
488         if ((len != OCFS2_STACK_LABEL_LEN) ||
489             (strnlen(buf, len) != len))
490                 return -EINVAL;
491
492         spin_lock(&ocfs2_stack_lock);
493         if (active_stack) {
494                 if (!strncmp(buf, cluster_stack_name, len))
495                         ret = count;
496                 else
497                         ret = -EBUSY;
498         } else {
499                 memcpy(cluster_stack_name, buf, len);
500                 ret = count;
501         }
502         spin_unlock(&ocfs2_stack_lock);
503
504         return ret;
505 }
506
507
508 static struct kobj_attribute ocfs2_attr_cluster_stack =
509         __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
510                ocfs2_cluster_stack_show,
511                ocfs2_cluster_stack_store);
512
513 static struct attribute *ocfs2_attrs[] = {
514         &ocfs2_attr_max_locking_protocol.attr,
515         &ocfs2_attr_loaded_cluster_plugins.attr,
516         &ocfs2_attr_active_cluster_plugin.attr,
517         &ocfs2_attr_cluster_stack.attr,
518         NULL,
519 };
520
521 static struct attribute_group ocfs2_attr_group = {
522         .attrs = ocfs2_attrs,
523 };
524
525 static struct kset *ocfs2_kset;
526
527 static void ocfs2_sysfs_exit(void)
528 {
529         kset_unregister(ocfs2_kset);
530 }
531
532 static int ocfs2_sysfs_init(void)
533 {
534         int ret;
535
536         ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
537         if (!ocfs2_kset)
538                 return -ENOMEM;
539
540         ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
541         if (ret)
542                 goto error;
543
544         return 0;
545
546 error:
547         kset_unregister(ocfs2_kset);
548         return ret;
549 }
550
551 static int __init ocfs2_stack_glue_init(void)
552 {
553         strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
554
555         return ocfs2_sysfs_init();
556 }
557
558 static void __exit ocfs2_stack_glue_exit(void)
559 {
560         lproto = NULL;
561         ocfs2_sysfs_exit();
562 }
563
564 MODULE_AUTHOR("Oracle");
565 MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
566 MODULE_LICENSE("GPL");
567 module_init(ocfs2_stack_glue_init);
568 module_exit(ocfs2_stack_glue_exit);