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DEFINITIONS
This source file includes following definitions.
- user_check_wait_flag
- user_wait_on_busy_lock
- user_wait_on_blocked_lock
- dlm_ctxt_from_user_lockres
- user_dlm_inode_from_user_lockres
- user_recover_from_dlm_error
- user_highest_compat_lock_level
- user_ast
- user_dlm_grab_inode_ref
- __user_dlm_queue_lockres
- __user_dlm_cond_queue_lockres
- user_bast
- user_unlock_ast
- user_dlm_drop_inode_ref
- user_dlm_unblock_lock
- user_dlm_inc_holders
- user_may_continue_on_blocked_lock
- user_dlm_cluster_lock
- user_dlm_dec_holders
- user_dlm_cluster_unlock
- user_dlm_write_lvb
- user_dlm_read_lvb
- user_dlm_lock_res_init
- user_dlm_destroy_lock
- user_dlm_register_context
- user_dlm_unregister_context
/* -*- 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);
}