linux/fs/ocfs2/dlm/userdlm.c
Joel Becker d24fbcda0c ocfs2: Negotiate locking protocol versions.
Currently, when ocfs2 nodes connect via TCP, they advertise their
compatibility level.  If the versions do not match, two nodes cannot speak
to each other and they disconnect. As a result, this provides no forward or
backwards compatibility.

This patch implements a simple protocol negotiation at the dlm level by
introducing a major/minor version number scheme for entities that
communicate.  Specifically, o2dlm has a major/minor version for interaction
with o2dlm on other nodes, and ocfs2 itself has a major/minor version for
interacting with the filesystem on other nodes.

This will allow rolling upgrades of ocfs2 clusters when changes to the
locking or network protocols can be done in a backwards compatible manner.
In those cases, only the minor number is changed and the negotatied protocol
minor is returned from dlm join. In the far less likely event that a
required protocol change makes backwards compatibility impossible, we simply
bump the major number.

Signed-off-by: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>
2008-02-06 16:11:29 -08:00

677 lines
16 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* userdlm.c
*
* Code which implements the kernel side of a minimal userspace
* interface to our DLM.
*
* Many of the functions here are pared down versions of dlmglue.c
* functions.
*
* Copyright (C) 2003, 2004 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; either
* version 2 of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <linux/signal.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/crc32.h>
#include "cluster/nodemanager.h"
#include "cluster/heartbeat.h"
#include "cluster/tcp.h"
#include "dlmapi.h"
#include "userdlm.h"
#define MLOG_MASK_PREFIX ML_DLMFS
#include "cluster/masklog.h"
static inline int user_check_wait_flag(struct user_lock_res *lockres,
int flag)
{
int ret;
spin_lock(&lockres->l_lock);
ret = lockres->l_flags & flag;
spin_unlock(&lockres->l_lock);
return ret;
}
static inline void user_wait_on_busy_lock(struct user_lock_res *lockres)
{
wait_event(lockres->l_event,
!user_check_wait_flag(lockres, USER_LOCK_BUSY));
}
static inline void user_wait_on_blocked_lock(struct user_lock_res *lockres)
{
wait_event(lockres->l_event,
!user_check_wait_flag(lockres, USER_LOCK_BLOCKED));
}
/* I heart container_of... */
static inline struct dlm_ctxt *
dlm_ctxt_from_user_lockres(struct user_lock_res *lockres)
{
struct dlmfs_inode_private *ip;
ip = container_of(lockres,
struct dlmfs_inode_private,
ip_lockres);
return ip->ip_dlm;
}
static struct inode *
user_dlm_inode_from_user_lockres(struct user_lock_res *lockres)
{
struct dlmfs_inode_private *ip;
ip = container_of(lockres,
struct dlmfs_inode_private,
ip_lockres);
return &ip->ip_vfs_inode;
}
static inline void user_recover_from_dlm_error(struct user_lock_res *lockres)
{
spin_lock(&lockres->l_lock);
lockres->l_flags &= ~USER_LOCK_BUSY;
spin_unlock(&lockres->l_lock);
}
#define user_log_dlm_error(_func, _stat, _lockres) do { \
mlog(ML_ERROR, "Dlm error \"%s\" while calling %s on " \
"resource %.*s: %s\n", dlm_errname(_stat), _func, \
_lockres->l_namelen, _lockres->l_name, dlm_errmsg(_stat)); \
} while (0)
/* WARNING: This function lives in a world where the only three lock
* levels are EX, PR, and NL. It *will* have to be adjusted when more
* lock types are added. */
static inline int user_highest_compat_lock_level(int level)
{
int new_level = LKM_EXMODE;
if (level == LKM_EXMODE)
new_level = LKM_NLMODE;
else if (level == LKM_PRMODE)
new_level = LKM_PRMODE;
return new_level;
}
static void user_ast(void *opaque)
{
struct user_lock_res *lockres = opaque;
struct dlm_lockstatus *lksb;
mlog(0, "AST fired for lockres %.*s\n", lockres->l_namelen,
lockres->l_name);
spin_lock(&lockres->l_lock);
lksb = &(lockres->l_lksb);
if (lksb->status != DLM_NORMAL) {
mlog(ML_ERROR, "lksb status value of %u on lockres %.*s\n",
lksb->status, lockres->l_namelen, lockres->l_name);
spin_unlock(&lockres->l_lock);
return;
}
mlog_bug_on_msg(lockres->l_requested == LKM_IVMODE,
"Lockres %.*s, requested ivmode. flags 0x%x\n",
lockres->l_namelen, lockres->l_name, lockres->l_flags);
/* we're downconverting. */
if (lockres->l_requested < lockres->l_level) {
if (lockres->l_requested <=
user_highest_compat_lock_level(lockres->l_blocking)) {
lockres->l_blocking = LKM_NLMODE;
lockres->l_flags &= ~USER_LOCK_BLOCKED;
}
}
lockres->l_level = lockres->l_requested;
lockres->l_requested = LKM_IVMODE;
lockres->l_flags |= USER_LOCK_ATTACHED;
lockres->l_flags &= ~USER_LOCK_BUSY;
spin_unlock(&lockres->l_lock);
wake_up(&lockres->l_event);
}
static inline void user_dlm_grab_inode_ref(struct user_lock_res *lockres)
{
struct inode *inode;
inode = user_dlm_inode_from_user_lockres(lockres);
if (!igrab(inode))
BUG();
}
static void user_dlm_unblock_lock(struct work_struct *work);
static void __user_dlm_queue_lockres(struct user_lock_res *lockres)
{
if (!(lockres->l_flags & USER_LOCK_QUEUED)) {
user_dlm_grab_inode_ref(lockres);
INIT_WORK(&lockres->l_work, user_dlm_unblock_lock);
queue_work(user_dlm_worker, &lockres->l_work);
lockres->l_flags |= USER_LOCK_QUEUED;
}
}
static void __user_dlm_cond_queue_lockres(struct user_lock_res *lockres)
{
int queue = 0;
if (!(lockres->l_flags & USER_LOCK_BLOCKED))
return;
switch (lockres->l_blocking) {
case LKM_EXMODE:
if (!lockres->l_ex_holders && !lockres->l_ro_holders)
queue = 1;
break;
case LKM_PRMODE:
if (!lockres->l_ex_holders)
queue = 1;
break;
default:
BUG();
}
if (queue)
__user_dlm_queue_lockres(lockres);
}
static void user_bast(void *opaque, int level)
{
struct user_lock_res *lockres = opaque;
mlog(0, "Blocking AST fired for lockres %.*s. Blocking level %d\n",
lockres->l_namelen, lockres->l_name, level);
spin_lock(&lockres->l_lock);
lockres->l_flags |= USER_LOCK_BLOCKED;
if (level > lockres->l_blocking)
lockres->l_blocking = level;
__user_dlm_queue_lockres(lockres);
spin_unlock(&lockres->l_lock);
wake_up(&lockres->l_event);
}
static void user_unlock_ast(void *opaque, enum dlm_status status)
{
struct user_lock_res *lockres = opaque;
mlog(0, "UNLOCK AST called on lock %.*s\n", lockres->l_namelen,
lockres->l_name);
if (status != DLM_NORMAL && status != DLM_CANCELGRANT)
mlog(ML_ERROR, "Dlm returns status %d\n", status);
spin_lock(&lockres->l_lock);
/* The teardown flag gets set early during the unlock process,
* so test the cancel flag to make sure that this ast isn't
* for a concurrent cancel. */
if (lockres->l_flags & USER_LOCK_IN_TEARDOWN
&& !(lockres->l_flags & USER_LOCK_IN_CANCEL)) {
lockres->l_level = LKM_IVMODE;
} else if (status == DLM_CANCELGRANT) {
/* We tried to cancel a convert request, but it was
* already granted. Don't clear the busy flag - the
* ast should've done this already. */
BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
goto out_noclear;
} else {
BUG_ON(!(lockres->l_flags & USER_LOCK_IN_CANCEL));
/* Cancel succeeded, we want to re-queue */
lockres->l_requested = LKM_IVMODE; /* cancel an
* upconvert
* request. */
lockres->l_flags &= ~USER_LOCK_IN_CANCEL;
/* we want the unblock thread to look at it again
* now. */
if (lockres->l_flags & USER_LOCK_BLOCKED)
__user_dlm_queue_lockres(lockres);
}
lockres->l_flags &= ~USER_LOCK_BUSY;
out_noclear:
spin_unlock(&lockres->l_lock);
wake_up(&lockres->l_event);
}
static inline void user_dlm_drop_inode_ref(struct user_lock_res *lockres)
{
struct inode *inode;
inode = user_dlm_inode_from_user_lockres(lockres);
iput(inode);
}
static void user_dlm_unblock_lock(struct work_struct *work)
{
int new_level, status;
struct user_lock_res *lockres =
container_of(work, struct user_lock_res, l_work);
struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
mlog(0, "processing lockres %.*s\n", lockres->l_namelen,
lockres->l_name);
spin_lock(&lockres->l_lock);
mlog_bug_on_msg(!(lockres->l_flags & USER_LOCK_QUEUED),
"Lockres %.*s, flags 0x%x\n",
lockres->l_namelen, lockres->l_name, lockres->l_flags);
/* notice that we don't clear USER_LOCK_BLOCKED here. If it's
* set, we want user_ast clear it. */
lockres->l_flags &= ~USER_LOCK_QUEUED;
/* It's valid to get here and no longer be blocked - if we get
* several basts in a row, we might be queued by the first
* one, the unblock thread might run and clear the queued
* flag, and finally we might get another bast which re-queues
* us before our ast for the downconvert is called. */
if (!(lockres->l_flags & USER_LOCK_BLOCKED)) {
spin_unlock(&lockres->l_lock);
goto drop_ref;
}
if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
spin_unlock(&lockres->l_lock);
goto drop_ref;
}
if (lockres->l_flags & USER_LOCK_BUSY) {
if (lockres->l_flags & USER_LOCK_IN_CANCEL) {
spin_unlock(&lockres->l_lock);
goto drop_ref;
}
lockres->l_flags |= USER_LOCK_IN_CANCEL;
spin_unlock(&lockres->l_lock);
status = dlmunlock(dlm,
&lockres->l_lksb,
LKM_CANCEL,
user_unlock_ast,
lockres);
if (status != DLM_NORMAL)
user_log_dlm_error("dlmunlock", status, lockres);
goto drop_ref;
}
/* If there are still incompat holders, we can exit safely
* without worrying about re-queueing this lock as that will
* happen on the last call to user_cluster_unlock. */
if ((lockres->l_blocking == LKM_EXMODE)
&& (lockres->l_ex_holders || lockres->l_ro_holders)) {
spin_unlock(&lockres->l_lock);
mlog(0, "can't downconvert for ex: ro = %u, ex = %u\n",
lockres->l_ro_holders, lockres->l_ex_holders);
goto drop_ref;
}
if ((lockres->l_blocking == LKM_PRMODE)
&& lockres->l_ex_holders) {
spin_unlock(&lockres->l_lock);
mlog(0, "can't downconvert for pr: ex = %u\n",
lockres->l_ex_holders);
goto drop_ref;
}
/* yay, we can downconvert now. */
new_level = user_highest_compat_lock_level(lockres->l_blocking);
lockres->l_requested = new_level;
lockres->l_flags |= USER_LOCK_BUSY;
mlog(0, "Downconvert lock from %d to %d\n",
lockres->l_level, new_level);
spin_unlock(&lockres->l_lock);
/* need lock downconvert request now... */
status = dlmlock(dlm,
new_level,
&lockres->l_lksb,
LKM_CONVERT|LKM_VALBLK,
lockres->l_name,
lockres->l_namelen,
user_ast,
lockres,
user_bast);
if (status != DLM_NORMAL) {
user_log_dlm_error("dlmlock", status, lockres);
user_recover_from_dlm_error(lockres);
}
drop_ref:
user_dlm_drop_inode_ref(lockres);
}
static inline void user_dlm_inc_holders(struct user_lock_res *lockres,
int level)
{
switch(level) {
case LKM_EXMODE:
lockres->l_ex_holders++;
break;
case LKM_PRMODE:
lockres->l_ro_holders++;
break;
default:
BUG();
}
}
/* predict what lock level we'll be dropping down to on behalf
* of another node, and return true if the currently wanted
* level will be compatible with it. */
static inline int
user_may_continue_on_blocked_lock(struct user_lock_res *lockres,
int wanted)
{
BUG_ON(!(lockres->l_flags & USER_LOCK_BLOCKED));
return wanted <= user_highest_compat_lock_level(lockres->l_blocking);
}
int user_dlm_cluster_lock(struct user_lock_res *lockres,
int level,
int lkm_flags)
{
int status, local_flags;
struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
if (level != LKM_EXMODE &&
level != LKM_PRMODE) {
mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
lockres->l_namelen, lockres->l_name);
status = -EINVAL;
goto bail;
}
mlog(0, "lockres %.*s: asking for %s lock, passed flags = 0x%x\n",
lockres->l_namelen, lockres->l_name,
(level == LKM_EXMODE) ? "LKM_EXMODE" : "LKM_PRMODE",
lkm_flags);
again:
if (signal_pending(current)) {
status = -ERESTARTSYS;
goto bail;
}
spin_lock(&lockres->l_lock);
/* We only compare against the currently granted level
* here. If the lock is blocked waiting on a downconvert,
* we'll get caught below. */
if ((lockres->l_flags & USER_LOCK_BUSY) &&
(level > lockres->l_level)) {
/* is someone sitting in dlm_lock? If so, wait on
* them. */
spin_unlock(&lockres->l_lock);
user_wait_on_busy_lock(lockres);
goto again;
}
if ((lockres->l_flags & USER_LOCK_BLOCKED) &&
(!user_may_continue_on_blocked_lock(lockres, level))) {
/* is the lock is currently blocked on behalf of
* another node */
spin_unlock(&lockres->l_lock);
user_wait_on_blocked_lock(lockres);
goto again;
}
if (level > lockres->l_level) {
local_flags = lkm_flags | LKM_VALBLK;
if (lockres->l_level != LKM_IVMODE)
local_flags |= LKM_CONVERT;
lockres->l_requested = level;
lockres->l_flags |= USER_LOCK_BUSY;
spin_unlock(&lockres->l_lock);
BUG_ON(level == LKM_IVMODE);
BUG_ON(level == LKM_NLMODE);
/* call dlm_lock to upgrade lock now */
status = dlmlock(dlm,
level,
&lockres->l_lksb,
local_flags,
lockres->l_name,
lockres->l_namelen,
user_ast,
lockres,
user_bast);
if (status != DLM_NORMAL) {
if ((lkm_flags & LKM_NOQUEUE) &&
(status == DLM_NOTQUEUED))
status = -EAGAIN;
else {
user_log_dlm_error("dlmlock", status, lockres);
status = -EINVAL;
}
user_recover_from_dlm_error(lockres);
goto bail;
}
user_wait_on_busy_lock(lockres);
goto again;
}
user_dlm_inc_holders(lockres, level);
spin_unlock(&lockres->l_lock);
status = 0;
bail:
return status;
}
static inline void user_dlm_dec_holders(struct user_lock_res *lockres,
int level)
{
switch(level) {
case LKM_EXMODE:
BUG_ON(!lockres->l_ex_holders);
lockres->l_ex_holders--;
break;
case LKM_PRMODE:
BUG_ON(!lockres->l_ro_holders);
lockres->l_ro_holders--;
break;
default:
BUG();
}
}
void user_dlm_cluster_unlock(struct user_lock_res *lockres,
int level)
{
if (level != LKM_EXMODE &&
level != LKM_PRMODE) {
mlog(ML_ERROR, "lockres %.*s: invalid request!\n",
lockres->l_namelen, lockres->l_name);
return;
}
spin_lock(&lockres->l_lock);
user_dlm_dec_holders(lockres, level);
__user_dlm_cond_queue_lockres(lockres);
spin_unlock(&lockres->l_lock);
}
void user_dlm_write_lvb(struct inode *inode,
const char *val,
unsigned int len)
{
struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
char *lvb = lockres->l_lksb.lvb;
BUG_ON(len > DLM_LVB_LEN);
spin_lock(&lockres->l_lock);
BUG_ON(lockres->l_level < LKM_EXMODE);
memcpy(lvb, val, len);
spin_unlock(&lockres->l_lock);
}
void user_dlm_read_lvb(struct inode *inode,
char *val,
unsigned int len)
{
struct user_lock_res *lockres = &DLMFS_I(inode)->ip_lockres;
char *lvb = lockres->l_lksb.lvb;
BUG_ON(len > DLM_LVB_LEN);
spin_lock(&lockres->l_lock);
BUG_ON(lockres->l_level < LKM_PRMODE);
memcpy(val, lvb, len);
spin_unlock(&lockres->l_lock);
}
void user_dlm_lock_res_init(struct user_lock_res *lockres,
struct dentry *dentry)
{
memset(lockres, 0, sizeof(*lockres));
spin_lock_init(&lockres->l_lock);
init_waitqueue_head(&lockres->l_event);
lockres->l_level = LKM_IVMODE;
lockres->l_requested = LKM_IVMODE;
lockres->l_blocking = LKM_IVMODE;
/* should have been checked before getting here. */
BUG_ON(dentry->d_name.len >= USER_DLM_LOCK_ID_MAX_LEN);
memcpy(lockres->l_name,
dentry->d_name.name,
dentry->d_name.len);
lockres->l_namelen = dentry->d_name.len;
}
int user_dlm_destroy_lock(struct user_lock_res *lockres)
{
int status = -EBUSY;
struct dlm_ctxt *dlm = dlm_ctxt_from_user_lockres(lockres);
mlog(0, "asked to destroy %.*s\n", lockres->l_namelen, lockres->l_name);
spin_lock(&lockres->l_lock);
if (lockres->l_flags & USER_LOCK_IN_TEARDOWN) {
spin_unlock(&lockres->l_lock);
return 0;
}
lockres->l_flags |= USER_LOCK_IN_TEARDOWN;
while (lockres->l_flags & USER_LOCK_BUSY) {
spin_unlock(&lockres->l_lock);
user_wait_on_busy_lock(lockres);
spin_lock(&lockres->l_lock);
}
if (lockres->l_ro_holders || lockres->l_ex_holders) {
spin_unlock(&lockres->l_lock);
goto bail;
}
status = 0;
if (!(lockres->l_flags & USER_LOCK_ATTACHED)) {
spin_unlock(&lockres->l_lock);
goto bail;
}
lockres->l_flags &= ~USER_LOCK_ATTACHED;
lockres->l_flags |= USER_LOCK_BUSY;
spin_unlock(&lockres->l_lock);
status = dlmunlock(dlm,
&lockres->l_lksb,
LKM_VALBLK,
user_unlock_ast,
lockres);
if (status != DLM_NORMAL) {
user_log_dlm_error("dlmunlock", status, lockres);
status = -EINVAL;
goto bail;
}
user_wait_on_busy_lock(lockres);
status = 0;
bail:
return status;
}
struct dlm_ctxt *user_dlm_register_context(struct qstr *name,
struct dlm_protocol_version *proto)
{
struct dlm_ctxt *dlm;
u32 dlm_key;
char *domain;
domain = kmalloc(name->len + 1, GFP_NOFS);
if (!domain) {
mlog_errno(-ENOMEM);
return ERR_PTR(-ENOMEM);
}
dlm_key = crc32_le(0, name->name, name->len);
snprintf(domain, name->len + 1, "%.*s", name->len, name->name);
dlm = dlm_register_domain(domain, dlm_key, proto);
if (IS_ERR(dlm))
mlog_errno(PTR_ERR(dlm));
kfree(domain);
return dlm;
}
void user_dlm_unregister_context(struct dlm_ctxt *dlm)
{
dlm_unregister_domain(dlm);
}