/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dlmast.c
 *
 * AST and BAST functionality for local and remote nodes
 *
 * Copyright (C) 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/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/random.h>
#include <linux/blkdev.h>
#include <linux/socket.h>
#include <linux/inet.h>
#include <linux/spinlock.h>


#include "cluster/heartbeat.h"
#include "cluster/nodemanager.h"
#include "cluster/tcp.h"

#include "dlmapi.h"
#include "dlmcommon.h"

#define MLOG_MASK_PREFIX ML_DLM
#include "cluster/masklog.h"

static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                           struct dlm_lock *lock);
static int dlm_should_cancel_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock);

/* Should be called as an ast gets queued to see if the new
 * lock level will obsolete a pending bast.
 * For example, if dlm_thread queued a bast for an EX lock that
 * was blocking another EX, but before sending the bast the
 * lock owner downconverted to NL, the bast is now obsolete.
 * Only the ast should be sent.
 * This is needed because the lock and convert paths can queue
 * asts out-of-band (not waiting for dlm_thread) in order to
 * allow for LKM_NOQUEUE to get immediate responses. */
static int dlm_should_cancel_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
{
        assert_spin_locked(&dlm->ast_lock);
        assert_spin_locked(&lock->spinlock);

        if (lock->ml.highest_blocked == LKM_IVMODE)
                return 0;
        BUG_ON(lock->ml.highest_blocked == LKM_NLMODE);

        if (lock->bast_pending &&
            list_empty(&lock->bast_list))
                /* old bast already sent, ok */
                return 0;

        if (lock->ml.type == LKM_EXMODE)
                /* EX blocks anything left, any bast still valid */
                return 0;
        else if (lock->ml.type == LKM_NLMODE)
                /* NL blocks nothing, no reason to send any bast, cancel it */
                return 1;
        else if (lock->ml.highest_blocked != LKM_EXMODE)
                /* PR only blocks EX */
                return 1;

        return 0;
}

static void __dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
{
        mlog_entry_void();

        BUG_ON(!dlm);
        BUG_ON(!lock);

        assert_spin_locked(&dlm->ast_lock);
        if (!list_empty(&lock->ast_list)) {
                mlog(ML_ERROR, "ast list not empty!!  pending=%d, newlevel=%d\n",
                     lock->ast_pending, lock->ml.type);
                BUG();
        }
        if (lock->ast_pending)
                mlog(0, "lock has an ast getting flushed right now\n");

        /* putting lock on list, add a ref */
        dlm_lock_get(lock);
        spin_lock(&lock->spinlock);

        /* check to see if this ast obsoletes the bast */
        if (dlm_should_cancel_bast(dlm, lock)) {
                struct dlm_lock_resource *res = lock->lockres;
                mlog(0, "%s: cancelling bast for %.*s\n",
                     dlm->name, res->lockname.len, res->lockname.name);
                lock->bast_pending = 0;
                list_del_init(&lock->bast_list);
                lock->ml.highest_blocked = LKM_IVMODE;
                /* removing lock from list, remove a ref.  guaranteed
                 * this won't be the last ref because of the get above,
                 * so res->spinlock will not be taken here */
                dlm_lock_put(lock);
                /* free up the reserved bast that we are cancelling.
                 * guaranteed that this will not be the last reserved
                 * ast because *both* an ast and a bast were reserved 
                 * to get to this point.  the res->spinlock will not be
                 * taken here */
                dlm_lockres_release_ast(dlm, res);
        }
        list_add_tail(&lock->ast_list, &dlm->pending_asts);
        lock->ast_pending = 1;
        spin_unlock(&lock->spinlock);
}

void dlm_queue_ast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
{
        mlog_entry_void();

        BUG_ON(!dlm);
        BUG_ON(!lock);

        spin_lock(&dlm->ast_lock);
        __dlm_queue_ast(dlm, lock);
        spin_unlock(&dlm->ast_lock);
}


static void __dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
{
        mlog_entry_void();

        BUG_ON(!dlm);
        BUG_ON(!lock);
        assert_spin_locked(&dlm->ast_lock);

        BUG_ON(!list_empty(&lock->bast_list));
        if (lock->bast_pending)
                mlog(0, "lock has a bast getting flushed right now\n");

        /* putting lock on list, add a ref */
        dlm_lock_get(lock);
        spin_lock(&lock->spinlock);
        list_add_tail(&lock->bast_list, &dlm->pending_basts);
        lock->bast_pending = 1;
        spin_unlock(&lock->spinlock);
}

void dlm_queue_bast(struct dlm_ctxt *dlm, struct dlm_lock *lock)
{
        mlog_entry_void();

        BUG_ON(!dlm);
        BUG_ON(!lock);

        spin_lock(&dlm->ast_lock);
        __dlm_queue_bast(dlm, lock);
        spin_unlock(&dlm->ast_lock);
}

static void dlm_update_lvb(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                           struct dlm_lock *lock)
{
        struct dlm_lockstatus *lksb = lock->lksb;
        BUG_ON(!lksb);

        /* only updates if this node masters the lockres */
        if (res->owner == dlm->node_num) {

                spin_lock(&res->spinlock);
                /* check the lksb flags for the direction */
                if (lksb->flags & DLM_LKSB_GET_LVB) {
                        mlog(0, "getting lvb from lockres for %s node\n",
                                  lock->ml.node == dlm->node_num ? "master" :
                                  "remote");
                        memcpy(lksb->lvb, res->lvb, DLM_LVB_LEN);
                }
                /* Do nothing for lvb put requests - they should be done in
                 * place when the lock is downconverted - otherwise we risk
                 * racing gets and puts which could result in old lvb data
                 * being propagated. We leave the put flag set and clear it
                 * here. In the future we might want to clear it at the time
                 * the put is actually done.
                 */
                spin_unlock(&res->spinlock);
        }

        /* reset any lvb flags on the lksb */
        lksb->flags &= ~(DLM_LKSB_PUT_LVB|DLM_LKSB_GET_LVB);
}

void dlm_do_local_ast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                      struct dlm_lock *lock)
{
        dlm_astlockfunc_t *fn;
        struct dlm_lockstatus *lksb;

        mlog_entry_void();

        lksb = lock->lksb;
        fn = lock->ast;
        BUG_ON(lock->ml.node != dlm->node_num);

        dlm_update_lvb(dlm, res, lock);
        (*fn)(lock->astdata);
}


int dlm_do_remote_ast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                      struct dlm_lock *lock)
{
        int ret;
        struct dlm_lockstatus *lksb;
        int lksbflags;

        mlog_entry_void();

        lksb = lock->lksb;
        BUG_ON(lock->ml.node == dlm->node_num);

        lksbflags = lksb->flags;
        dlm_update_lvb(dlm, res, lock);

        /* lock request came from another node
         * go do the ast over there */
        ret = dlm_send_proxy_ast(dlm, res, lock, lksbflags);
        return ret;
}

void dlm_do_local_bast(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                       struct dlm_lock *lock, int blocked_type)
{
        dlm_bastlockfunc_t *fn = lock->bast;

        mlog_entry_void();
        BUG_ON(lock->ml.node != dlm->node_num);

        (*fn)(lock->astdata, blocked_type);
}



int dlm_proxy_ast_handler(struct o2net_msg *msg, u32 len, void *data,
                          void **ret_data)
{
        int ret;
        unsigned int locklen;
        struct dlm_ctxt *dlm = data;
        struct dlm_lock_resource *res = NULL;
        struct dlm_lock *lock = NULL;
        struct dlm_proxy_ast *past = (struct dlm_proxy_ast *) msg->buf;
        char *name;
        struct list_head *iter, *head=NULL;
        u64 cookie;
        u32 flags;
        u8 node;

        if (!dlm_grab(dlm)) {
                dlm_error(DLM_REJECTED);
                return DLM_REJECTED;
        }

        mlog_bug_on_msg(!dlm_domain_fully_joined(dlm),
                        "Domain %s not fully joined!\n", dlm->name);

        name = past->name;
        locklen = past->namelen;
        cookie = past->cookie;
        flags = be32_to_cpu(past->flags);
        node = past->node_idx;

        if (locklen > DLM_LOCKID_NAME_MAX) {
                ret = DLM_IVBUFLEN;
                mlog(ML_ERROR, "Invalid name length (%d) in proxy ast "
                     "handler!\n", locklen);
                goto leave;
        }

        if ((flags & (LKM_PUT_LVB|LKM_GET_LVB)) ==
             (LKM_PUT_LVB|LKM_GET_LVB)) {
                mlog(ML_ERROR, "Both PUT and GET lvb specified, (0x%x)\n",
                     flags);
                ret = DLM_BADARGS;
                goto leave;
        }

        mlog(0, "lvb: %s\n", flags & LKM_PUT_LVB ? "put lvb" :
                  (flags & LKM_GET_LVB ? "get lvb" : "none"));

        mlog(0, "type=%d, blocked_type=%d\n", past->type, past->blocked_type);

        if (past->type != DLM_AST &&
            past->type != DLM_BAST) {
                mlog(ML_ERROR, "Unknown ast type! %d, cookie=%u:%llu"
                     "name=%.*s, node=%u\n", past->type,
                     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
                     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
                     locklen, name, node);
                ret = DLM_IVLOCKID;
                goto leave;
        }

        res = dlm_lookup_lockres(dlm, name, locklen);
        if (!res) {
                mlog(0, "Got %sast for unknown lockres! cookie=%u:%llu, "
                     "name=%.*s, node=%u\n", (past->type == DLM_AST ? "" : "b"),
                     dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
                     dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
                     locklen, name, node);
                ret = DLM_IVLOCKID;
                goto leave;
        }

        /* cannot get a proxy ast message if this node owns it */
        BUG_ON(res->owner == dlm->node_num);

        mlog(0, "lockres %.*s\n", res->lockname.len, res->lockname.name);

        spin_lock(&res->spinlock);
        if (res->state & DLM_LOCK_RES_RECOVERING) {
                mlog(0, "Responding with DLM_RECOVERING!\n");
                ret = DLM_RECOVERING;
                goto unlock_out;
        }
        if (res->state & DLM_LOCK_RES_MIGRATING) {
                mlog(0, "Responding with DLM_MIGRATING!\n");
                ret = DLM_MIGRATING;
                goto unlock_out;
        }
        /* try convert queue for both ast/bast */
        head = &res->converting;
        lock = NULL;
        list_for_each(iter, head) {
                lock = list_entry (iter, struct dlm_lock, list);
                if (lock->ml.cookie == cookie)
                        goto do_ast;
        }

        /* if not on convert, try blocked for ast, granted for bast */
        if (past->type == DLM_AST)
                head = &res->blocked;
        else
                head = &res->granted;

        list_for_each(iter, head) {
                lock = list_entry (iter, struct dlm_lock, list);
                if (lock->ml.cookie == cookie)
                        goto do_ast;
        }

        mlog(0, "Got %sast for unknown lock! cookie=%u:%llu, name=%.*s, "
             "node=%u\n", past->type == DLM_AST ? "" : "b",
             dlm_get_lock_cookie_node(be64_to_cpu(cookie)),
             dlm_get_lock_cookie_seq(be64_to_cpu(cookie)),
             locklen, name, node);

        ret = DLM_NORMAL;
unlock_out:
        spin_unlock(&res->spinlock);
        goto leave;

do_ast:
        ret = DLM_NORMAL;
        if (past->type == DLM_AST) {
                /* do not alter lock refcount.  switching lists. */
                list_move_tail(&lock->list, &res->granted);
                mlog(0, "ast: Adding to granted list... type=%d, "
                     "convert_type=%d\n", lock->ml.type, lock->ml.convert_type);
                if (lock->ml.convert_type != LKM_IVMODE) {
                        lock->ml.type = lock->ml.convert_type;
                        lock->ml.convert_type = LKM_IVMODE;
                } else {
                        // should already be there....
                }

                lock->lksb->status = DLM_NORMAL;

                /* if we requested the lvb, fetch it into our lksb now */
                if (flags & LKM_GET_LVB) {
                        BUG_ON(!(lock->lksb->flags & DLM_LKSB_GET_LVB));
                        memcpy(lock->lksb->lvb, past->lvb, DLM_LVB_LEN);
                }
        }
        spin_unlock(&res->spinlock);

        if (past->type == DLM_AST)
                dlm_do_local_ast(dlm, res, lock);
        else
                dlm_do_local_bast(dlm, res, lock, past->blocked_type);

leave:
        if (res)
                dlm_lockres_put(res);

        dlm_put(dlm);
        return ret;
}



int dlm_send_proxy_ast_msg(struct dlm_ctxt *dlm, struct dlm_lock_resource *res,
                           struct dlm_lock *lock, int msg_type,
                           int blocked_type, int flags)
{
        int ret = 0;
        struct dlm_proxy_ast past;
        struct kvec vec[2];
        size_t veclen = 1;
        int status;

        mlog_entry("res %.*s, to=%u, type=%d, blocked_type=%d\n",
                   res->lockname.len, res->lockname.name, lock->ml.node,
                   msg_type, blocked_type);

        memset(&past, 0, sizeof(struct dlm_proxy_ast));
        past.node_idx = dlm->node_num;
        past.type = msg_type;
        past.blocked_type = blocked_type;
        past.namelen = res->lockname.len;
        memcpy(past.name, res->lockname.name, past.namelen);
        past.cookie = lock->ml.cookie;

        vec[0].iov_len = sizeof(struct dlm_proxy_ast);
        vec[0].iov_base = &past;
        if (flags & DLM_LKSB_GET_LVB) {
                mlog(0, "returning requested LVB data\n");
                be32_add_cpu(&past.flags, LKM_GET_LVB);
                vec[1].iov_len = DLM_LVB_LEN;
                vec[1].iov_base = lock->lksb->lvb;
                veclen++;
        }

        ret = o2net_send_message_vec(DLM_PROXY_AST_MSG, dlm->key, vec, veclen,
                                     lock->ml.node, &status);
        if (ret < 0)
                mlog_errno(ret);
        else {
                if (status == DLM_RECOVERING) {
                        mlog(ML_ERROR, "sent AST to node %u, it thinks this "
                             "node is dead!\n", lock->ml.node);
                        BUG();
                } else if (status == DLM_MIGRATING) {
                        mlog(ML_ERROR, "sent AST to node %u, it returned "
                             "DLM_MIGRATING!\n", lock->ml.node);
                        BUG();
                } else if (status != DLM_NORMAL && status != DLM_IVLOCKID) {
                        mlog(ML_ERROR, "AST to node %u returned %d!\n",
                             lock->ml.node, status);
                        /* ignore it */
                }
                ret = 0;
        }
        return ret;
}