linux/fs/ocfs2/stackglue.c
Joel Becker 1c520dfbf3 ocfs2: Provide the ocfs2_dlm_lvb_valid() stack API.
The Lock Value Block (LVB) of a DLM lock can be lost when nodes die and
the DLM cannot reconstruct its state.  Clients of the DLM need to know
this.

ocfs2's internal DLM, o2dlm, explicitly zeroes out the LVB when it loses
track of the state.  This is not a standard behavior, but ocfs2 has
always relied on it.  Thus, an o2dlm LVB is always "valid".

ocfs2 now supports both o2dlm and fs/dlm via the stack glue.  When
fs/dlm loses track of an LVBs state, it sets a flag
(DLM_SBF_VALNOTVALID) on the Lock Status Block (LKSB).  The contents of
the LVB may be garbage or merely stale.

ocfs2 doesn't want to try to guess at the validity of the stale LVB.
Instead, it should be checking the VALNOTVALID flag.  As this is the
'standard' way of treating LVBs, we will promote this behavior.

We add a stack glue API ocfs2_dlm_lvb_valid().  It returns non-zero when
the LVB is valid.  o2dlm will always return valid, while fs/dlm will
check VALNOTVALID.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Acked-by: Mark Fasheh <mfasheh@suse.com>
2009-06-22 14:24:30 -07:00

704 lines
16 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* stackglue.c
*
* Code which implements an OCFS2 specific interface to underlying
* cluster stacks.
*
* Copyright (C) 2007, 2009 Oracle. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation, version 2.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*/
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kmod.h>
#include <linux/fs.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/sysctl.h>
#include "ocfs2_fs.h"
#include "stackglue.h"
#define OCFS2_STACK_PLUGIN_O2CB "o2cb"
#define OCFS2_STACK_PLUGIN_USER "user"
#define OCFS2_MAX_HB_CTL_PATH 256
static struct ocfs2_locking_protocol *lproto;
static DEFINE_SPINLOCK(ocfs2_stack_lock);
static LIST_HEAD(ocfs2_stack_list);
static char cluster_stack_name[OCFS2_STACK_LABEL_LEN + 1];
static char ocfs2_hb_ctl_path[OCFS2_MAX_HB_CTL_PATH] = "/sbin/ocfs2_hb_ctl";
/*
* The stack currently in use. If not null, active_stack->sp_count > 0,
* the module is pinned, and the locking protocol cannot be changed.
*/
static struct ocfs2_stack_plugin *active_stack;
static struct ocfs2_stack_plugin *ocfs2_stack_lookup(const char *name)
{
struct ocfs2_stack_plugin *p;
assert_spin_locked(&ocfs2_stack_lock);
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
if (!strcmp(p->sp_name, name))
return p;
}
return NULL;
}
static int ocfs2_stack_driver_request(const char *stack_name,
const char *plugin_name)
{
int rc;
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
/*
* If the stack passed by the filesystem isn't the selected one,
* we can't continue.
*/
if (strcmp(stack_name, cluster_stack_name)) {
rc = -EBUSY;
goto out;
}
if (active_stack) {
/*
* If the active stack isn't the one we want, it cannot
* be selected right now.
*/
if (!strcmp(active_stack->sp_name, plugin_name))
rc = 0;
else
rc = -EBUSY;
goto out;
}
p = ocfs2_stack_lookup(plugin_name);
if (!p || !try_module_get(p->sp_owner)) {
rc = -ENOENT;
goto out;
}
active_stack = p;
rc = 0;
out:
/* If we found it, pin it */
if (!rc)
active_stack->sp_count++;
spin_unlock(&ocfs2_stack_lock);
return rc;
}
/*
* This function looks up the appropriate stack and makes it active. If
* there is no stack, it tries to load it. It will fail if the stack still
* cannot be found. It will also fail if a different stack is in use.
*/
static int ocfs2_stack_driver_get(const char *stack_name)
{
int rc;
char *plugin_name = OCFS2_STACK_PLUGIN_O2CB;
/*
* Classic stack does not pass in a stack name. This is
* compatible with older tools as well.
*/
if (!stack_name || !*stack_name)
stack_name = OCFS2_STACK_PLUGIN_O2CB;
if (strlen(stack_name) != OCFS2_STACK_LABEL_LEN) {
printk(KERN_ERR
"ocfs2 passed an invalid cluster stack label: \"%s\"\n",
stack_name);
return -EINVAL;
}
/* Anything that isn't the classic stack is a user stack */
if (strcmp(stack_name, OCFS2_STACK_PLUGIN_O2CB))
plugin_name = OCFS2_STACK_PLUGIN_USER;
rc = ocfs2_stack_driver_request(stack_name, plugin_name);
if (rc == -ENOENT) {
request_module("ocfs2_stack_%s", plugin_name);
rc = ocfs2_stack_driver_request(stack_name, plugin_name);
}
if (rc == -ENOENT) {
printk(KERN_ERR
"ocfs2: Cluster stack driver \"%s\" cannot be found\n",
plugin_name);
} else if (rc == -EBUSY) {
printk(KERN_ERR
"ocfs2: A different cluster stack is in use\n");
}
return rc;
}
static void ocfs2_stack_driver_put(void)
{
spin_lock(&ocfs2_stack_lock);
BUG_ON(active_stack == NULL);
BUG_ON(active_stack->sp_count == 0);
active_stack->sp_count--;
if (!active_stack->sp_count) {
module_put(active_stack->sp_owner);
active_stack = NULL;
}
spin_unlock(&ocfs2_stack_lock);
}
int ocfs2_stack_glue_register(struct ocfs2_stack_plugin *plugin)
{
int rc;
spin_lock(&ocfs2_stack_lock);
if (!ocfs2_stack_lookup(plugin->sp_name)) {
plugin->sp_count = 0;
plugin->sp_proto = lproto;
list_add(&plugin->sp_list, &ocfs2_stack_list);
printk(KERN_INFO "ocfs2: Registered cluster interface %s\n",
plugin->sp_name);
rc = 0;
} else {
printk(KERN_ERR "ocfs2: Stack \"%s\" already registered\n",
plugin->sp_name);
rc = -EEXIST;
}
spin_unlock(&ocfs2_stack_lock);
return rc;
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_register);
void ocfs2_stack_glue_unregister(struct ocfs2_stack_plugin *plugin)
{
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
p = ocfs2_stack_lookup(plugin->sp_name);
if (p) {
BUG_ON(p != plugin);
BUG_ON(plugin == active_stack);
BUG_ON(plugin->sp_count != 0);
list_del_init(&plugin->sp_list);
printk(KERN_INFO "ocfs2: Unregistered cluster interface %s\n",
plugin->sp_name);
} else {
printk(KERN_ERR "Stack \"%s\" is not registered\n",
plugin->sp_name);
}
spin_unlock(&ocfs2_stack_lock);
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_unregister);
void ocfs2_stack_glue_set_locking_protocol(struct ocfs2_locking_protocol *proto)
{
struct ocfs2_stack_plugin *p;
BUG_ON(proto == NULL);
spin_lock(&ocfs2_stack_lock);
BUG_ON(active_stack != NULL);
lproto = proto;
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
p->sp_proto = lproto;
}
spin_unlock(&ocfs2_stack_lock);
}
EXPORT_SYMBOL_GPL(ocfs2_stack_glue_set_locking_protocol);
/*
* The ocfs2_dlm_lock() and ocfs2_dlm_unlock() functions take
* "struct ocfs2_lock_res *astarg" instead of "void *astarg" because the
* underlying stack plugins need to pilfer the lksb off of the lock_res.
* If some other structure needs to be passed as an astarg, the plugins
* will need to be given a different avenue to the lksb.
*/
int ocfs2_dlm_lock(struct ocfs2_cluster_connection *conn,
int mode,
union ocfs2_dlm_lksb *lksb,
u32 flags,
void *name,
unsigned int namelen,
struct ocfs2_lock_res *astarg)
{
BUG_ON(lproto == NULL);
return active_stack->sp_ops->dlm_lock(conn, mode, lksb, flags,
name, namelen, astarg);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lock);
int ocfs2_dlm_unlock(struct ocfs2_cluster_connection *conn,
union ocfs2_dlm_lksb *lksb,
u32 flags,
struct ocfs2_lock_res *astarg)
{
BUG_ON(lproto == NULL);
return active_stack->sp_ops->dlm_unlock(conn, lksb, flags, astarg);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_unlock);
int ocfs2_dlm_lock_status(union ocfs2_dlm_lksb *lksb)
{
return active_stack->sp_ops->lock_status(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lock_status);
int ocfs2_dlm_lvb_valid(union ocfs2_dlm_lksb *lksb)
{
return active_stack->sp_ops->lvb_valid(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb_valid);
void *ocfs2_dlm_lvb(union ocfs2_dlm_lksb *lksb)
{
return active_stack->sp_ops->lock_lvb(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_lvb);
void ocfs2_dlm_dump_lksb(union ocfs2_dlm_lksb *lksb)
{
active_stack->sp_ops->dump_lksb(lksb);
}
EXPORT_SYMBOL_GPL(ocfs2_dlm_dump_lksb);
int ocfs2_stack_supports_plocks(void)
{
return active_stack && active_stack->sp_ops->plock;
}
EXPORT_SYMBOL_GPL(ocfs2_stack_supports_plocks);
/*
* ocfs2_plock() can only be safely called if
* ocfs2_stack_supports_plocks() returned true
*/
int ocfs2_plock(struct ocfs2_cluster_connection *conn, u64 ino,
struct file *file, int cmd, struct file_lock *fl)
{
WARN_ON_ONCE(active_stack->sp_ops->plock == NULL);
if (active_stack->sp_ops->plock)
return active_stack->sp_ops->plock(conn, ino, file, cmd, fl);
return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(ocfs2_plock);
int ocfs2_cluster_connect(const char *stack_name,
const char *group,
int grouplen,
void (*recovery_handler)(int node_num,
void *recovery_data),
void *recovery_data,
struct ocfs2_cluster_connection **conn)
{
int rc = 0;
struct ocfs2_cluster_connection *new_conn;
BUG_ON(group == NULL);
BUG_ON(conn == NULL);
BUG_ON(recovery_handler == NULL);
if (grouplen > GROUP_NAME_MAX) {
rc = -EINVAL;
goto out;
}
new_conn = kzalloc(sizeof(struct ocfs2_cluster_connection),
GFP_KERNEL);
if (!new_conn) {
rc = -ENOMEM;
goto out;
}
memcpy(new_conn->cc_name, group, grouplen);
new_conn->cc_namelen = grouplen;
new_conn->cc_recovery_handler = recovery_handler;
new_conn->cc_recovery_data = recovery_data;
/* Start the new connection at our maximum compatibility level */
new_conn->cc_version = lproto->lp_max_version;
/* This will pin the stack driver if successful */
rc = ocfs2_stack_driver_get(stack_name);
if (rc)
goto out_free;
rc = active_stack->sp_ops->connect(new_conn);
if (rc) {
ocfs2_stack_driver_put();
goto out_free;
}
*conn = new_conn;
out_free:
if (rc)
kfree(new_conn);
out:
return rc;
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_connect);
/* If hangup_pending is 0, the stack driver will be dropped */
int ocfs2_cluster_disconnect(struct ocfs2_cluster_connection *conn,
int hangup_pending)
{
int ret;
BUG_ON(conn == NULL);
ret = active_stack->sp_ops->disconnect(conn);
/* XXX Should we free it anyway? */
if (!ret) {
kfree(conn);
if (!hangup_pending)
ocfs2_stack_driver_put();
}
return ret;
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_disconnect);
/*
* Leave the group for this filesystem. This is executed by a userspace
* program (stored in ocfs2_hb_ctl_path).
*/
static void ocfs2_leave_group(const char *group)
{
int ret;
char *argv[5], *envp[3];
argv[0] = ocfs2_hb_ctl_path;
argv[1] = "-K";
argv[2] = "-u";
argv[3] = (char *)group;
argv[4] = NULL;
/* minimal command environment taken from cpu_run_sbin_hotplug */
envp[0] = "HOME=/";
envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
envp[2] = NULL;
ret = call_usermodehelper(argv[0], argv, envp, UMH_WAIT_PROC);
if (ret < 0) {
printk(KERN_ERR
"ocfs2: Error %d running user helper "
"\"%s %s %s %s\"\n",
ret, argv[0], argv[1], argv[2], argv[3]);
}
}
/*
* Hangup is a required post-umount. ocfs2-tools software expects the
* filesystem to call "ocfs2_hb_ctl" during unmount. This happens
* regardless of whether the DLM got started, so we can't do it
* in ocfs2_cluster_disconnect(). The ocfs2_leave_group() function does
* the actual work.
*/
void ocfs2_cluster_hangup(const char *group, int grouplen)
{
BUG_ON(group == NULL);
BUG_ON(group[grouplen] != '\0');
ocfs2_leave_group(group);
/* cluster_disconnect() was called with hangup_pending==1 */
ocfs2_stack_driver_put();
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_hangup);
int ocfs2_cluster_this_node(unsigned int *node)
{
return active_stack->sp_ops->this_node(node);
}
EXPORT_SYMBOL_GPL(ocfs2_cluster_this_node);
/*
* Sysfs bits
*/
static ssize_t ocfs2_max_locking_protocol_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0;
spin_lock(&ocfs2_stack_lock);
if (lproto)
ret = snprintf(buf, PAGE_SIZE, "%u.%u\n",
lproto->lp_max_version.pv_major,
lproto->lp_max_version.pv_minor);
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_max_locking_protocol =
__ATTR(max_locking_protocol, S_IFREG | S_IRUGO,
ocfs2_max_locking_protocol_show, NULL);
static ssize_t ocfs2_loaded_cluster_plugins_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0, total = 0, remain = PAGE_SIZE;
struct ocfs2_stack_plugin *p;
spin_lock(&ocfs2_stack_lock);
list_for_each_entry(p, &ocfs2_stack_list, sp_list) {
ret = snprintf(buf, remain, "%s\n",
p->sp_name);
if (ret < 0) {
total = ret;
break;
}
if (ret == remain) {
/* snprintf() didn't fit */
total = -E2BIG;
break;
}
total += ret;
remain -= ret;
}
spin_unlock(&ocfs2_stack_lock);
return total;
}
static struct kobj_attribute ocfs2_attr_loaded_cluster_plugins =
__ATTR(loaded_cluster_plugins, S_IFREG | S_IRUGO,
ocfs2_loaded_cluster_plugins_show, NULL);
static ssize_t ocfs2_active_cluster_plugin_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret = 0;
spin_lock(&ocfs2_stack_lock);
if (active_stack) {
ret = snprintf(buf, PAGE_SIZE, "%s\n",
active_stack->sp_name);
if (ret == PAGE_SIZE)
ret = -E2BIG;
}
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_active_cluster_plugin =
__ATTR(active_cluster_plugin, S_IFREG | S_IRUGO,
ocfs2_active_cluster_plugin_show, NULL);
static ssize_t ocfs2_cluster_stack_show(struct kobject *kobj,
struct kobj_attribute *attr,
char *buf)
{
ssize_t ret;
spin_lock(&ocfs2_stack_lock);
ret = snprintf(buf, PAGE_SIZE, "%s\n", cluster_stack_name);
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static ssize_t ocfs2_cluster_stack_store(struct kobject *kobj,
struct kobj_attribute *attr,
const char *buf, size_t count)
{
size_t len = count;
ssize_t ret;
if (len == 0)
return len;
if (buf[len - 1] == '\n')
len--;
if ((len != OCFS2_STACK_LABEL_LEN) ||
(strnlen(buf, len) != len))
return -EINVAL;
spin_lock(&ocfs2_stack_lock);
if (active_stack) {
if (!strncmp(buf, cluster_stack_name, len))
ret = count;
else
ret = -EBUSY;
} else {
memcpy(cluster_stack_name, buf, len);
ret = count;
}
spin_unlock(&ocfs2_stack_lock);
return ret;
}
static struct kobj_attribute ocfs2_attr_cluster_stack =
__ATTR(cluster_stack, S_IFREG | S_IRUGO | S_IWUSR,
ocfs2_cluster_stack_show,
ocfs2_cluster_stack_store);
static struct attribute *ocfs2_attrs[] = {
&ocfs2_attr_max_locking_protocol.attr,
&ocfs2_attr_loaded_cluster_plugins.attr,
&ocfs2_attr_active_cluster_plugin.attr,
&ocfs2_attr_cluster_stack.attr,
NULL,
};
static struct attribute_group ocfs2_attr_group = {
.attrs = ocfs2_attrs,
};
static struct kset *ocfs2_kset;
static void ocfs2_sysfs_exit(void)
{
kset_unregister(ocfs2_kset);
}
static int ocfs2_sysfs_init(void)
{
int ret;
ocfs2_kset = kset_create_and_add("ocfs2", NULL, fs_kobj);
if (!ocfs2_kset)
return -ENOMEM;
ret = sysfs_create_group(&ocfs2_kset->kobj, &ocfs2_attr_group);
if (ret)
goto error;
return 0;
error:
kset_unregister(ocfs2_kset);
return ret;
}
/*
* Sysctl bits
*
* The sysctl lives at /proc/sys/fs/ocfs2/nm/hb_ctl_path. The 'nm' doesn't
* make as much sense in a multiple cluster stack world, but it's safer
* and easier to preserve the name.
*/
#define FS_OCFS2_NM 1
static ctl_table ocfs2_nm_table[] = {
{
.ctl_name = 1,
.procname = "hb_ctl_path",
.data = ocfs2_hb_ctl_path,
.maxlen = OCFS2_MAX_HB_CTL_PATH,
.mode = 0644,
.proc_handler = &proc_dostring,
.strategy = &sysctl_string,
},
{ .ctl_name = 0 }
};
static ctl_table ocfs2_mod_table[] = {
{
.ctl_name = FS_OCFS2_NM,
.procname = "nm",
.data = NULL,
.maxlen = 0,
.mode = 0555,
.child = ocfs2_nm_table
},
{ .ctl_name = 0}
};
static ctl_table ocfs2_kern_table[] = {
{
.ctl_name = FS_OCFS2,
.procname = "ocfs2",
.data = NULL,
.maxlen = 0,
.mode = 0555,
.child = ocfs2_mod_table
},
{ .ctl_name = 0}
};
static ctl_table ocfs2_root_table[] = {
{
.ctl_name = CTL_FS,
.procname = "fs",
.data = NULL,
.maxlen = 0,
.mode = 0555,
.child = ocfs2_kern_table
},
{ .ctl_name = 0 }
};
static struct ctl_table_header *ocfs2_table_header = NULL;
/*
* Initialization
*/
static int __init ocfs2_stack_glue_init(void)
{
strcpy(cluster_stack_name, OCFS2_STACK_PLUGIN_O2CB);
ocfs2_table_header = register_sysctl_table(ocfs2_root_table);
if (!ocfs2_table_header) {
printk(KERN_ERR
"ocfs2 stack glue: unable to register sysctl\n");
return -ENOMEM; /* or something. */
}
return ocfs2_sysfs_init();
}
static void __exit ocfs2_stack_glue_exit(void)
{
lproto = NULL;
ocfs2_sysfs_exit();
if (ocfs2_table_header)
unregister_sysctl_table(ocfs2_table_header);
}
MODULE_AUTHOR("Oracle");
MODULE_DESCRIPTION("ocfs2 cluter stack glue layer");
MODULE_LICENSE("GPL");
module_init(ocfs2_stack_glue_init);
module_exit(ocfs2_stack_glue_exit);