Root/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, 2009 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#define OCFS2_MAX_HB_CTL_PATH 256
38
39static struct ocfs2_protocol_version locking_max_version;
40static DEFINE_SPINLOCK(ocfs2_stack_lock);
41static LIST_HEAD(ocfs2_stack_list);
42static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
43static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
44
45/*
46 * The stack currently in use. If not null, active_stack->sp_count > 0,
47 * the module is pinned, and the locking protocol cannot be changed.
48 */
49static struct ocfs2_stack_plugin *active_stack;
50
51static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
52{
53    struct ocfs2_stack_plugin *p;
54
55    assert_spin_locked(&ocfs2_stack_lock);
56
57    list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
58        if (!strcmp(p->sp_name, name))
59            return p;
60    }
61
62    return NULL;
63}
64
65static int ocfs2_stack_driver_request(const char *stack_name,
66                      const char *plugin_name)
67{
68    int rc;
69    struct ocfs2_stack_plugin *p;
70
71    spin_lock(&ocfs2_stack_lock);
72
73    /*
74     * If the stack passed by the filesystem isn't the selected one,
75     * we can't continue.
76     */
77    if (strcmp(stack_name, cluster_stack_name)) {
78        rc = -EBUSY;
79        goto out;
80    }
81
82    if (active_stack) {
83        /*
84         * If the active stack isn't the one we want, it cannot
85         * be selected right now.
86         */
87        if (!strcmp(active_stack->sp_name, plugin_name))
88            rc = 0;
89        else
90            rc = -EBUSY;
91        goto out;
92    }
93
94    p = ocfs2_stack_lookup(plugin_name);
95    if (!p || !try_module_get(p->sp_owner)) {
96        rc = -ENOENT;
97        goto out;
98    }
99
100    active_stack = p;
101    rc = 0;
102
103out:
104    /* If we found it, pin it */
105    if (!rc)
106        active_stack->sp_count++;
107
108    spin_unlock(&ocfs2_stack_lock);
109    return rc;
110}
111
112/*
113 * This function looks up the appropriate stack and makes it active. If
114 * there is no stack, it tries to load it. It will fail if the stack still
115 * cannot be found. It will also fail if a different stack is in use.
116 */
117static int ocfs2_stack_driver_get(const char *stack_name)
118{
119    int rc;
120    char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
121
122    /*
123     * Classic stack does not pass in a stack name. This is
124     * compatible with older tools as well.
125     */
126    if (!stack_name || !*stack_name)
127        stack_name = OCFS2_STACK_PLUGIN_O2CB;
128
129    if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
130        printk(KERN_ERR
131               "ocfs2 passed an invalid cluster stack label: \"%s\"\n",
132               stack_name);
133        return -EINVAL;
134    }
135
136    /* Anything that isn't the classic stack is a user stack */
137    if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
138        plugin_name = OCFS2_STACK_PLUGIN_USER;
139
140    rc = ocfs2_stack_driver_request(stack_name, plugin_name);
141    if (rc == -ENOENT) {
142        request_module("ocfs2_stack_%s", plugin_name);
143        rc = ocfs2_stack_driver_request(stack_name, plugin_name);
144    }
145
146    if (rc == -ENOENT) {
147        printk(KERN_ERR
148               "ocfs2: Cluster stack driver \"%s\" cannot be found\n",
149               plugin_name);
150    } else if (rc == -EBUSY) {
151        printk(KERN_ERR
152               "ocfs2: A different cluster stack is in use\n");
153    }
154
155    return rc;
156}
157
158static void ocfs2_stack_driver_put(void)
159{
160    spin_lock(&ocfs2_stack_lock);
161    BUG_ON(active_stack == NULL);
162    BUG_ON(active_stack->sp_count == 0);
163
164    active_stack->sp_count--;
165    if (!active_stack->sp_count) {
166        module_put(active_stack->sp_owner);
167        active_stack = NULL;
168    }
169    spin_unlock(&ocfs2_stack_lock);
170}
171
172int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
173{
174    int rc;
175
176    spin_lock(&ocfs2_stack_lock);
177    if (!ocfs2_stack_lookup(plugin->sp_name)) {
178        plugin->sp_count = 0;
179        plugin->sp_max_proto = locking_max_version;
180        list_add(&plugin->sp_list, &ocfs2_stack_list);
181        printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
182               plugin->sp_name);
183        rc = 0;
184    } else {
185        printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
186               plugin->sp_name);
187        rc = -EEXIST;
188    }
189    spin_unlock(&ocfs2_stack_lock);
190
191    return rc;
192}
193EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
194
195void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
196{
197    struct ocfs2_stack_plugin *p;
198
199    spin_lock(&ocfs2_stack_lock);
200    p = ocfs2_stack_lookup(plugin->sp_name);
201    if (p) {
202        BUG_ON(p != plugin);
203        BUG_ON(plugin == active_stack);
204        BUG_ON(plugin->sp_count != 0);
205        list_del_init(&plugin->sp_list);
206        printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
207               plugin->sp_name);
208    } else {
209        printk(KERN_ERR "Stack \"%s\" is not registered\n",
210               plugin->sp_name);
211    }
212    spin_unlock(&ocfs2_stack_lock);
213}
214EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
215
216void ocfs2_stack_glue_set_max_proto_version(struct ocfs2_protocol_version *max_proto)
217{
218    struct ocfs2_stack_plugin *p;
219
220    spin_lock(&ocfs2_stack_lock);
221    if (memcmp(max_proto, &locking_max_version,
222           sizeof(struct ocfs2_protocol_version))) {
223        BUG_ON(locking_max_version.pv_major != 0);
224
225        locking_max_version = *max_proto;
226        list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
227            p->sp_max_proto = locking_max_version;
228        }
229    }
230    spin_unlock(&ocfs2_stack_lock);
231}
232EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_max_proto_version);
233
234
235/*
236 * The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take no argument
237 * for the ast and bast functions. They will pass the lksb to the ast
238 * and bast. The caller can wrap the lksb with their own structure to
239 * get more information.
240 */
241int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
242           int mode,
243           struct ocfs2_dlm_lksb *lksb,
244           u32 flags,
245           void *name,
246           unsigned int namelen)
247{
248    if (!lksb->lksb_conn)
249        lksb->lksb_conn = conn;
250    else
251        BUG_ON(lksb->lksb_conn != conn);
252    return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
253                          name, namelen);
254}
255EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
256
257int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
258             struct ocfs2_dlm_lksb *lksb,
259             u32 flags)
260{
261    BUG_ON(lksb->lksb_conn == NULL);
262
263    return active_stack->sp_ops->dlm_unlock(conn, lksb, flags);
264}
265EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
266
267int ocfs2_dlm_lock_status(struct ocfs2_dlm_lksb *lksb)
268{
269    return active_stack->sp_ops->lock_status(lksb);
270}
271EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
272
273int ocfs2_dlm_lvb_valid(struct ocfs2_dlm_lksb *lksb)
274{
275    return active_stack->sp_ops->lvb_valid(lksb);
276}
277EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb_valid);
278
279void *ocfs2_dlm_lvb(struct ocfs2_dlm_lksb *lksb)
280{
281    return active_stack->sp_ops->lock_lvb(lksb);
282}
283EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
284
285void ocfs2_dlm_dump_lksb(struct ocfs2_dlm_lksb *lksb)
286{
287    active_stack->sp_ops->dump_lksb(lksb);
288}
289EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
290
291int ocfs2_stack_supports_plocks(void)
292{
293    return active_stack && active_stack->sp_ops->plock;
294}
295EXPORT_SYMBOL_GPL(ocfs2_stack_supports_plocks);
296
297/*
298 * ocfs2_plock() can only be safely called if
299 * ocfs2_stack_supports_plocks() returned true
300 */
301int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
302        struct file *file, int cmd, struct file_lock *fl)
303{
304    WARN_ON_ONCE(active_stack->sp_ops->plock == NULL);
305    if (active_stack->sp_ops->plock)
306        return active_stack->sp_ops->plock(conn, ino, file, cmd, fl);
307    return -EOPNOTSUPP;
308}
309EXPORT_SYMBOL_GPL(ocfs2_plock);
310
311int ocfs2_cluster_connect(const char *stack_name,
312              const char *group,
313              int grouplen,
314              struct ocfs2_locking_protocol *lproto,
315              void (*recovery_handler)(int node_num,
316                           void *recovery_data),
317              void *recovery_data,
318              struct ocfs2_cluster_connection **conn)
319{
320    int rc = 0;
321    struct ocfs2_cluster_connection *new_conn;
322
323    BUG_ON(group == NULL);
324    BUG_ON(conn == NULL);
325    BUG_ON(recovery_handler == NULL);
326
327    if (grouplen > GROUP_NAME_MAX) {
328        rc = -EINVAL;
329        goto out;
330    }
331
332    if (memcmp(&lproto->lp_max_version, &locking_max_version,
333           sizeof(struct ocfs2_protocol_version))) {
334        rc = -EINVAL;
335        goto out;
336    }
337
338    new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
339               GFP_KERNEL);
340    if (!new_conn) {
341        rc = -ENOMEM;
342        goto out;
343    }
344
345    memcpy(new_conn->cc_name, group, grouplen);
346    new_conn->cc_namelen = grouplen;
347    new_conn->cc_recovery_handler = recovery_handler;
348    new_conn->cc_recovery_data = recovery_data;
349
350    new_conn->cc_proto = lproto;
351    /* Start the new connection at our maximum compatibility level */
352    new_conn->cc_version = lproto->lp_max_version;
353
354    /* This will pin the stack driver if successful */
355    rc = ocfs2_stack_driver_get(stack_name);
356    if (rc)
357        goto out_free;
358
359    rc = active_stack->sp_ops->connect(new_conn);
360    if (rc) {
361        ocfs2_stack_driver_put();
362        goto out_free;
363    }
364
365    *conn = new_conn;
366
367out_free:
368    if (rc)
369        kfree(new_conn);
370
371out:
372    return rc;
373}
374EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
375
376/* The caller will ensure all nodes have the same cluster stack */
377int ocfs2_cluster_connect_agnostic(const char *group,
378                   int grouplen,
379                   struct ocfs2_locking_protocol *lproto,
380                   void (*recovery_handler)(int node_num,
381                                void *recovery_data),
382                   void *recovery_data,
383                   struct ocfs2_cluster_connection **conn)
384{
385    char *stack_name = NULL;
386
387    if (cluster_stack_name[0])
388        stack_name = cluster_stack_name;
389    return ocfs2_cluster_connect(stack_name, group, grouplen, lproto,
390                     recovery_handler, recovery_data, conn);
391}
392EXPORT_SYMBOL_GPL(ocfs2_cluster_connect_agnostic);
393
394/* If hangup_pending is 0, the stack driver will be dropped */
395int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
396                 int hangup_pending)
397{
398    int ret;
399
400    BUG_ON(conn == NULL);
401
402    ret = active_stack->sp_ops->disconnect(conn);
403
404    /* XXX Should we free it anyway? */
405    if (!ret) {
406        kfree(conn);
407        if (!hangup_pending)
408            ocfs2_stack_driver_put();
409    }
410
411    return ret;
412}
413EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
414
415/*
416 * Leave the group for this filesystem. This is executed by a userspace
417 * program (stored in ocfs2_hb_ctl_path).
418 */
419static void ocfs2_leave_group(const char *group)
420{
421    int ret;
422    char *argv[5], *envp[3];
423
424    argv[0] = ocfs2_hb_ctl_path;
425    argv[1] = "-K";
426    argv[2] = "-u";
427    argv[3] = (char *)group;
428    argv[4] = NULL;
429
430    /* minimal command environment taken from cpu_run_sbin_hotplug */
431    envp[0] = "HOME=/";
432    envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
433    envp[2] = NULL;
434
435    ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
436    if (ret < 0) {
437        printk(KERN_ERR
438               "ocfs2: Error %d running user helper "
439               "\"%s %s %s %s\"\n",
440               ret, argv[0], argv[1], argv[2], argv[3]);
441    }
442}
443
444/*
445 * Hangup is a required post-umount. ocfs2-tools software expects the
446 * filesystem to call "ocfs2_hb_ctl" during unmount. This happens
447 * regardless of whether the DLM got started, so we can't do it
448 * in ocfs2_cluster_disconnect(). The ocfs2_leave_group() function does
449 * the actual work.
450 */
451void ocfs2_cluster_hangup(const char *group, int grouplen)
452{
453    BUG_ON(group == NULL);
454    BUG_ON(group[grouplen] != '\0');
455
456    ocfs2_leave_group(group);
457
458    /* cluster_disconnect() was called with hangup_pending==1 */
459    ocfs2_stack_driver_put();
460}
461EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
462
463int ocfs2_cluster_this_node(unsigned int *node)
464{
465    return active_stack->sp_ops->this_node(node);
466}
467EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
468
469
470/*
471 * Sysfs bits
472 */
473
474static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
475                           struct kobj_attribute *attr,
476                           char *buf)
477{
478    ssize_t ret = 0;
479
480    spin_lock(&ocfs2_stack_lock);
481    if (locking_max_version.pv_major)
482        ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
483                   locking_max_version.pv_major,
484                   locking_max_version.pv_minor);
485    spin_unlock(&ocfs2_stack_lock);
486
487    return ret;
488}
489
490static struct kobj_attribute ocfs2_attr_max_locking_protocol =
491    __ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
492           ocfs2_max_locking_protocol_show, NULL);
493
494static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
495                         struct kobj_attribute *attr,
496                         char *buf)
497{
498    ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
499    struct ocfs2_stack_plugin *p;
500
501    spin_lock(&ocfs2_stack_lock);
502    list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
503        ret = snprintf(buf, remain, "%s\n",
504                   p->sp_name);
505        if (ret < 0) {
506            total = ret;
507            break;
508        }
509        if (ret == remain) {
510            /* snprintf() didn't fit */
511            total = -E2BIG;
512            break;
513        }
514        total += ret;
515        remain -= ret;
516    }
517    spin_unlock(&ocfs2_stack_lock);
518
519    return total;
520}
521
522static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
523    __ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
524           ocfs2_loaded_cluster_plugins_show, NULL);
525
526static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
527                        struct kobj_attribute *attr,
528                        char *buf)
529{
530    ssize_t ret = 0;
531
532    spin_lock(&ocfs2_stack_lock);
533    if (active_stack) {
534        ret = snprintf(buf, PAGE_SIZE, "%s\n",
535                   active_stack->sp_name);
536        if (ret == PAGE_SIZE)
537            ret = -E2BIG;
538    }
539    spin_unlock(&ocfs2_stack_lock);
540
541    return ret;
542}
543
544static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
545    __ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
546           ocfs2_active_cluster_plugin_show, NULL);
547
548static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
549                    struct kobj_attribute *attr,
550                    char *buf)
551{
552    ssize_t ret;
553    spin_lock(&ocfs2_stack_lock);
554    ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
555    spin_unlock(&ocfs2_stack_lock);
556
557    return ret;
558}
559
560static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
561                     struct kobj_attribute *attr,
562                     const char *buf, size_t count)
563{
564    size_t len = count;
565    ssize_t ret;
566
567    if (len == 0)
568        return len;
569
570    if (buf[len - 1] == '\n')
571        len--;
572
573    if ((len != OCFS2_STACK_LABEL_LEN) ||
574        (strnlen(buf, len) != len))
575        return -EINVAL;
576
577    spin_lock(&ocfs2_stack_lock);
578    if (active_stack) {
579        if (!strncmp(buf, cluster_stack_name, len))
580            ret = count;
581        else
582            ret = -EBUSY;
583    } else {
584        memcpy(cluster_stack_name, buf, len);
585        ret = count;
586    }
587    spin_unlock(&ocfs2_stack_lock);
588
589    return ret;
590}
591
592
593static struct kobj_attribute ocfs2_attr_cluster_stack =
594    __ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
595           ocfs2_cluster_stack_show,
596           ocfs2_cluster_stack_store);
597
598static struct attribute *ocfs2_attrs[] = {
599    &ocfs2_attr_max_locking_protocol.attr,
600    &ocfs2_attr_loaded_cluster_plugins.attr,
601    &ocfs2_attr_active_cluster_plugin.attr,
602    &ocfs2_attr_cluster_stack.attr,
603    NULL,
604};
605
606static struct attribute_group ocfs2_attr_group = {
607    .attrs = ocfs2_attrs,
608};
609
610static struct kset *ocfs2_kset;
611
612static void ocfs2_sysfs_exit(void)
613{
614    kset_unregister(ocfs2_kset);
615}
616
617static int ocfs2_sysfs_init(void)
618{
619    int ret;
620
621    ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
622    if (!ocfs2_kset)
623        return -ENOMEM;
624
625    ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
626    if (ret)
627        goto error;
628
629    return 0;
630
631error:
632    kset_unregister(ocfs2_kset);
633    return ret;
634}
635
636/*
637 * Sysctl bits
638 *
639 * The sysctl lives at /proc/sys/fs/ocfs2/nm/hb_ctl_path. The 'nm' doesn't
640 * make as much sense in a multiple cluster stack world, but it's safer
641 * and easier to preserve the name.
642 */
643
644#define FS_OCFS2_NM 1
645
646static ctl_table ocfs2_nm_table[] = {
647    {
648        .procname = "hb_ctl_path",
649        .data = ocfs2_hb_ctl_path,
650        .maxlen = OCFS2_MAX_HB_CTL_PATH,
651        .mode = 0644,
652        .proc_handler = proc_dostring,
653    },
654    { }
655};
656
657static ctl_table ocfs2_mod_table[] = {
658    {
659        .procname = "nm",
660        .data = NULL,
661        .maxlen = 0,
662        .mode = 0555,
663        .child = ocfs2_nm_table
664    },
665    { }
666};
667
668static ctl_table ocfs2_kern_table[] = {
669    {
670        .procname = "ocfs2",
671        .data = NULL,
672        .maxlen = 0,
673        .mode = 0555,
674        .child = ocfs2_mod_table
675    },
676    { }
677};
678
679static ctl_table ocfs2_root_table[] = {
680    {
681        .procname = "fs",
682        .data = NULL,
683        .maxlen = 0,
684        .mode = 0555,
685        .child = ocfs2_kern_table
686    },
687    { }
688};
689
690static struct ctl_table_header *ocfs2_table_header = NULL;
691
692
693/*
694 * Initialization
695 */
696
697static int __init ocfs2_stack_glue_init(void)
698{
699    strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
700
701    ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
702    if (!ocfs2_table_header) {
703        printk(KERN_ERR
704               "ocfs2 stack glue: unable to register sysctl\n");
705        return -ENOMEM; /* or something. */
706    }
707
708    return ocfs2_sysfs_init();
709}
710
711static void __exit ocfs2_stack_glue_exit(void)
712{
713    memset(&locking_max_version, 0,
714           sizeof(struct ocfs2_protocol_version));
715    locking_max_version.pv_major = 0;
716    locking_max_version.pv_minor = 0;
717    ocfs2_sysfs_exit();
718    if (ocfs2_table_header)
719        unregister_sysctl_table(ocfs2_table_header);
720}
721
722MODULE_AUTHOR("Oracle");
723MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
724MODULE_LICENSE("GPL");
725module_init(ocfs2_stack_glue_init);
726module_exit(ocfs2_stack_glue_exit);
727

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