ocfs2: Move the hb_ctl_path sysctl into the stack glue.
[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 #include <linux/sysctl.h>
30
31 #include "ocfs2_fs.h"
32
33 #include "stackglue.h"
34
35 #define OCFS2_STACK_PLUGIN_O2CB         "o2cb"
36 #define OCFS2_STACK_PLUGIN_USER         "user"
37
38 static struct ocfs2_locking_protocol *lproto;
39 static DEFINE_SPINLOCK(ocfs2_stack_lock);
40 static LIST_HEAD(ocfs2_stack_list);
41 static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
42
43 /*
44  * The stack currently in use.  If not null, active_stack->sp_count > 0,
45  * the module is pinned, and the locking protocol cannot be changed.
46  */
47 static struct ocfs2_stack_plugin *active_stack;
48
49 static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
50 {
51         struct ocfs2_stack_plugin *p;
52
53         assert_spin_locked(&ocfs2_stack_lock);
54
55         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
56                 if (!strcmp(p->sp_name, name))
57                         return p;
58         }
59
60         return NULL;
61 }
62
63 static int ocfs2_stack_driver_request(const char *stack_name,
64                                       const char *plugin_name)
65 {
66         int rc;
67         struct ocfs2_stack_plugin *p;
68
69         spin_lock(&ocfs2_stack_lock);
70
71         /*
72          * If the stack passed by the filesystem isn't the selected one,
73          * we can't continue.
74          */
75         if (strcmp(stack_name, cluster_stack_name)) {
76                 rc = -EBUSY;
77                 goto out;
78         }
79
80         if (active_stack) {
81                 /*
82                  * If the active stack isn't the one we want, it cannot
83                  * be selected right now.
84                  */
85                 if (!strcmp(active_stack->sp_name, plugin_name))
86                         rc = 0;
87                 else
88                         rc = -EBUSY;
89                 goto out;
90         }
91
92         p = ocfs2_stack_lookup(plugin_name);
93         if (!p || !try_module_get(p->sp_owner)) {
94                 rc = -ENOENT;
95                 goto out;
96         }
97
98         /* Ok, the stack is pinned */
99         p->sp_count++;
100         active_stack = p;
101
102         rc = 0;
103
104 out:
105         spin_unlock(&ocfs2_stack_lock);
106         return rc;
107 }
108
109 /*
110  * This function looks up the appropriate stack and makes it active.  If
111  * there is no stack, it tries to load it.  It will fail if the stack still
112  * cannot be found.  It will also fail if a different stack is in use.
113  */
114 static int ocfs2_stack_driver_get(const char *stack_name)
115 {
116         int rc;
117         char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
118
119         /*
120          * Classic stack does not pass in a stack name.  This is
121          * compatible with older tools as well.
122          */
123         if (!stack_name || !*stack_name)
124                 stack_name = OCFS2_STACK_PLUGIN_O2CB;
125
126         if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
127                 printk(KERN_ERR
128                        "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
129                        stack_name);
130                 return -EINVAL;
131         }
132
133         /* Anything that isn't the classic stack is a user stack */
134         if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
135                 plugin_name = OCFS2_STACK_PLUGIN_USER;
136
137         rc = ocfs2_stack_driver_request(stack_name, plugin_name);
138         if (rc == -ENOENT) {
139                 request_module("ocfs2_stack_%s", plugin_name);
140                 rc = ocfs2_stack_driver_request(stack_name, plugin_name);
141         }
142
143         if (rc == -ENOENT) {
144                 printk(KERN_ERR
145                        "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
146                        plugin_name);
147         } else if (rc == -EBUSY) {
148                 printk(KERN_ERR
149                        "ocfs2: A different cluster stack is in use\n");
150         }
151
152         return rc;
153 }
154
155 static void ocfs2_stack_driver_put(void)
156 {
157         spin_lock(&ocfs2_stack_lock);
158         BUG_ON(active_stack == NULL);
159         BUG_ON(active_stack->sp_count == 0);
160
161         active_stack->sp_count--;
162         if (!active_stack->sp_count) {
163                 module_put(active_stack->sp_owner);
164                 active_stack = NULL;
165         }
166         spin_unlock(&ocfs2_stack_lock);
167 }
168
169 int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
170 {
171         int rc;
172
173         spin_lock(&ocfs2_stack_lock);
174         if (!ocfs2_stack_lookup(plugin->sp_name)) {
175                 plugin->sp_count = 0;
176                 plugin->sp_proto = lproto;
177                 list_add(&plugin->sp_list, &ocfs2_stack_list);
178                 printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
179                        plugin->sp_name);
180                 rc = 0;
181         } else {
182                 printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
183                        plugin->sp_name);
184                 rc = -EEXIST;
185         }
186         spin_unlock(&ocfs2_stack_lock);
187
188         return rc;
189 }
190 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
191
192 void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
193 {
194         struct ocfs2_stack_plugin *p;
195
196         spin_lock(&ocfs2_stack_lock);
197         p = ocfs2_stack_lookup(plugin->sp_name);
198         if (p) {
199                 BUG_ON(p != plugin);
200                 BUG_ON(plugin == active_stack);
201                 BUG_ON(plugin->sp_count != 0);
202                 list_del_init(&plugin->sp_list);
203                 printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
204                        plugin->sp_name);
205         } else {
206                 printk(KERN_ERR "Stack \"%s\" is not registered\n",
207                        plugin->sp_name);
208         }
209         spin_unlock(&ocfs2_stack_lock);
210 }
211 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
212
213 void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
214 {
215         struct ocfs2_stack_plugin *p;
216
217         BUG_ON(proto == NULL);
218
219         spin_lock(&ocfs2_stack_lock);
220         BUG_ON(active_stack != NULL);
221
222         lproto = proto;
223         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
224                 p->sp_proto = lproto;
225         }
226
227         spin_unlock(&ocfs2_stack_lock);
228 }
229 EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
230
231
232 /*
233  * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
234  * "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
235  * underlying stack plugins need to pilfer the lksb off of the lock_res.
236  * If some other structure needs to be passed as an astarg, the plugins
237  * will need to be given a different avenue to the lksb.
238  */
239 int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
240                    int mode,
241                    union ocfs2_dlm_lksb *lksb,
242                    u32 flags,
243                    void *name,
244                    unsigned int namelen,
245                    struct ocfs2_lock_res *astarg)
246 {
247         BUG_ON(lproto == NULL);
248
249         return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
250                                               name, namelen, astarg);
251 }
252 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
253
254 int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
255                      union ocfs2_dlm_lksb *lksb,
256                      u32 flags,
257                      struct ocfs2_lock_res *astarg)
258 {
259         BUG_ON(lproto == NULL);
260
261         return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
262 }
263 EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
264
265 int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
266 {
267         return active_stack->sp_ops->lock_status(lksb);
268 }
269 EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
270
271 /*
272  * Why don't we cast to ocfs2_meta_lvb?  The "clean" answer is that we
273  * don't cast at the glue level.  The real answer is that the header
274  * ordering is nigh impossible.
275  */
276 void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
277 {
278         return active_stack->sp_ops->lock_lvb(lksb);
279 }
280 EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
281
282 void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
283 {
284         active_stack->sp_ops->dump_lksb(lksb);
285 }
286 EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
287
288 int ocfs2_cluster_connect(const char *stack_name,
289                           const char *group,
290                           int grouplen,
291                           void (*recovery_handler)(int node_num,
292                                                    void *recovery_data),
293                           void *recovery_data,
294                           struct ocfs2_cluster_connection **conn)
295 {
296         int rc = 0;
297         struct ocfs2_cluster_connection *new_conn;
298
299         BUG_ON(group == NULL);
300         BUG_ON(conn == NULL);
301         BUG_ON(recovery_handler == NULL);
302
303         if (grouplen > GROUP_NAME_MAX) {
304                 rc = -EINVAL;
305                 goto out;
306         }
307
308         new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
309                            GFP_KERNEL);
310         if (!new_conn) {
311                 rc = -ENOMEM;
312                 goto out;
313         }
314
315         memcpy(new_conn->cc_name, group, grouplen);
316         new_conn->cc_namelen = grouplen;
317         new_conn->cc_recovery_handler = recovery_handler;
318         new_conn->cc_recovery_data = recovery_data;
319
320         /* Start the new connection at our maximum compatibility level */
321         new_conn->cc_version = lproto->lp_max_version;
322
323         /* This will pin the stack driver if successful */
324         rc = ocfs2_stack_driver_get(stack_name);
325         if (rc)
326                 goto out_free;
327
328         rc = active_stack->sp_ops->connect(new_conn);
329         if (rc) {
330                 ocfs2_stack_driver_put();
331                 goto out_free;
332         }
333
334         *conn = new_conn;
335
336 out_free:
337         if (rc)
338                 kfree(new_conn);
339
340 out:
341         return rc;
342 }
343 EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
344
345 /* If hangup_pending is 0, the stack driver will be dropped */
346 int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
347                              int hangup_pending)
348 {
349         int ret;
350
351         BUG_ON(conn == NULL);
352
353         ret = active_stack->sp_ops->disconnect(conn, hangup_pending);
354
355         /* XXX Should we free it anyway? */
356         if (!ret) {
357                 kfree(conn);
358                 if (!hangup_pending)
359                         ocfs2_stack_driver_put();
360         }
361
362         return ret;
363 }
364 EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
365
366 void ocfs2_cluster_hangup(const char *group, int grouplen)
367 {
368         BUG_ON(group == NULL);
369         BUG_ON(group[grouplen] != '\0');
370
371         if (active_stack->sp_ops->hangup)
372                 active_stack->sp_ops->hangup(group, grouplen);
373
374         /* cluster_disconnect() was called with hangup_pending==1 */
375         ocfs2_stack_driver_put();
376 }
377 EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
378
379 int ocfs2_cluster_this_node(unsigned int *node)
380 {
381         return active_stack->sp_ops->this_node(node);
382 }
383 EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
384
385
386 /*
387  * Sysfs bits
388  */
389
390 static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
391                                                struct kobj_attribute *attr,
392                                                char *buf)
393 {
394         ssize_t ret = 0;
395
396         spin_lock(&ocfs2_stack_lock);
397         if (lproto)
398                 ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
399                                lproto->lp_max_version.pv_major,
400                                lproto->lp_max_version.pv_minor);
401         spin_unlock(&ocfs2_stack_lock);
402
403         return ret;
404 }
405
406 static struct kobj_attribute ocfs2_attr_max_locking_protocol =
407         __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
408                ocfs2_max_locking_protocol_show, NULL);
409
410 static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
411                                                  struct kobj_attribute *attr,
412                                                  char *buf)
413 {
414         ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
415         struct ocfs2_stack_plugin *p;
416
417         spin_lock(&ocfs2_stack_lock);
418         list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
419                 ret = snprintf(buf, remain, "%s\n",
420                                p->sp_name);
421                 if (ret < 0) {
422                         total = ret;
423                         break;
424                 }
425                 if (ret == remain) {
426                         /* snprintf() didn't fit */
427                         total = -E2BIG;
428                         break;
429                 }
430                 total += ret;
431                 remain -= ret;
432         }
433         spin_unlock(&ocfs2_stack_lock);
434
435         return total;
436 }
437
438 static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
439         __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
440                ocfs2_loaded_cluster_plugins_show, NULL);
441
442 static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
443                                                 struct kobj_attribute *attr,
444                                                 char *buf)
445 {
446         ssize_t ret = 0;
447
448         spin_lock(&ocfs2_stack_lock);
449         if (active_stack) {
450                 ret = snprintf(buf, PAGE_SIZE, "%s\n",
451                                active_stack->sp_name);
452                 if (ret == PAGE_SIZE)
453                         ret = -E2BIG;
454         }
455         spin_unlock(&ocfs2_stack_lock);
456
457         return ret;
458 }
459
460 static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
461         __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
462                ocfs2_active_cluster_plugin_show, NULL);
463
464 static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
465                                         struct kobj_attribute *attr,
466                                         char *buf)
467 {
468         ssize_t ret;
469         spin_lock(&ocfs2_stack_lock);
470         ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
471         spin_unlock(&ocfs2_stack_lock);
472
473         return ret;
474 }
475
476 static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
477                                          struct kobj_attribute *attr,
478                                          const char *buf, size_t count)
479 {
480         size_t len = count;
481         ssize_t ret;
482
483         if (len == 0)
484                 return len;
485
486         if (buf[len - 1] == '\n')
487                 len--;
488
489         if ((len != OCFS2_STACK_LABEL_LEN) ||
490             (strnlen(buf, len) != len))
491                 return -EINVAL;
492
493         spin_lock(&ocfs2_stack_lock);
494         if (active_stack) {
495                 if (!strncmp(buf, cluster_stack_name, len))
496                         ret = count;
497                 else
498                         ret = -EBUSY;
499         } else {
500                 memcpy(cluster_stack_name, buf, len);
501                 ret = count;
502         }
503         spin_unlock(&ocfs2_stack_lock);
504
505         return ret;
506 }
507
508
509 static struct kobj_attribute ocfs2_attr_cluster_stack =
510         __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
511                ocfs2_cluster_stack_show,
512                ocfs2_cluster_stack_store);
513
514 static struct attribute *ocfs2_attrs[] = {
515         &ocfs2_attr_max_locking_protocol.attr,
516         &ocfs2_attr_loaded_cluster_plugins.attr,
517         &ocfs2_attr_active_cluster_plugin.attr,
518         &ocfs2_attr_cluster_stack.attr,
519         NULL,
520 };
521
522 static struct attribute_group ocfs2_attr_group = {
523         .attrs = ocfs2_attrs,
524 };
525
526 static struct kset *ocfs2_kset;
527
528 static void ocfs2_sysfs_exit(void)
529 {
530         kset_unregister(ocfs2_kset);
531 }
532
533 static int ocfs2_sysfs_init(void)
534 {
535         int ret;
536
537         ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
538         if (!ocfs2_kset)
539                 return -ENOMEM;
540
541         ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
542         if (ret)
543                 goto error;
544
545         return 0;
546
547 error:
548         kset_unregister(ocfs2_kset);
549         return ret;
550 }
551
552 /*
553  * Sysctl bits
554  *
555  * The sysctl lives at /proc/sys/fs/ocfs2/nm/hb_ctl_path.  The 'nm' doesn't
556  * make as much sense in a multiple cluster stack world, but it's safer
557  * and easier to preserve the name.
558  */
559
560 #define FS_OCFS2_NM             1
561
562 #define OCFS2_MAX_HB_CTL_PATH 256
563 static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
564
565 static ctl_table ocfs2_nm_table[] = {
566         {
567                 .ctl_name       = 1,
568                 .procname       = "hb_ctl_path",
569                 .data           = ocfs2_hb_ctl_path,
570                 .maxlen         = OCFS2_MAX_HB_CTL_PATH,
571                 .mode           = 0644,
572                 .proc_handler   = &proc_dostring,
573                 .strategy       = &sysctl_string,
574         },
575         { .ctl_name = 0 }
576 };
577
578 static ctl_table ocfs2_mod_table[] = {
579         {
580                 .ctl_name       = FS_OCFS2_NM,
581                 .procname       = "nm",
582                 .data           = NULL,
583                 .maxlen         = 0,
584                 .mode           = 0555,
585                 .child          = ocfs2_nm_table
586         },
587         { .ctl_name = 0}
588 };
589
590 static ctl_table ocfs2_kern_table[] = {
591         {
592                 .ctl_name       = FS_OCFS2,
593                 .procname       = "ocfs2",
594                 .data           = NULL,
595                 .maxlen         = 0,
596                 .mode           = 0555,
597                 .child          = ocfs2_mod_table
598         },
599         { .ctl_name = 0}
600 };
601
602 static ctl_table ocfs2_root_table[] = {
603         {
604                 .ctl_name       = CTL_FS,
605                 .procname       = "fs",
606                 .data           = NULL,
607                 .maxlen         = 0,
608                 .mode           = 0555,
609                 .child          = ocfs2_kern_table
610         },
611         { .ctl_name = 0 }
612 };
613
614 static struct ctl_table_header *ocfs2_table_header = NULL;
615
616 const char *ocfs2_get_hb_ctl_path(void)
617 {
618         return ocfs2_hb_ctl_path;
619 }
620 EXPORT_SYMBOL_GPL(ocfs2_get_hb_ctl_path);
621
622
623 /*
624  * Initialization
625  */
626
627 static int __init ocfs2_stack_glue_init(void)
628 {
629         strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
630
631         ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
632         if (!ocfs2_table_header) {
633                 printk(KERN_ERR
634                        "ocfs2 stack glue: unable to register sysctl\n");
635                 return -ENOMEM; /* or something. */
636         }
637
638         return ocfs2_sysfs_init();
639 }
640
641 static void __exit ocfs2_stack_glue_exit(void)
642 {
643         lproto = NULL;
644         ocfs2_sysfs_exit();
645         if (ocfs2_table_header)
646                 unregister_sysctl_table(ocfs2_table_header);
647 }
648
649 MODULE_AUTHOR("Oracle");
650 MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
651 MODULE_LICENSE("GPL");
652 module_init(ocfs2_stack_glue_init);
653 module_exit(ocfs2_stack_glue_exit);