// SPDX-License-Identifier: GPL-2.0-only
/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2011 Red Hat, Inc.  All rights reserved.
**
**
*******************************************************************************
******************************************************************************/

#include "dlm_internal.h"
#include "lockspace.h"
#include "member.h"
#include "dir.h"
#include "ast.h"
#include "recover.h"
#include "lowcomms.h"
#include "lock.h"
#include "requestqueue.h"
#include "recoverd.h"

static int dlm_create_masters_list(struct dlm_ls *ls)
{
        struct dlm_rsb *r;
        int error = 0;

        write_lock_bh(&ls->ls_masters_lock);
        if (!list_empty(&ls->ls_masters_list)) {
                log_error(ls, "root list not empty");
                error = -EINVAL;
                goto out;
        }

        read_lock_bh(&ls->ls_rsbtbl_lock);
        list_for_each_entry(r, &ls->ls_slow_active, res_slow_list) {
                if (r->res_nodeid)
                        continue;

                list_add(&r->res_masters_list, &ls->ls_masters_list);
                dlm_hold_rsb(r);
        }
        read_unlock_bh(&ls->ls_rsbtbl_lock);
 out:
        write_unlock_bh(&ls->ls_masters_lock);
        return error;
}

static void dlm_release_masters_list(struct dlm_ls *ls)
{
        struct dlm_rsb *r, *safe;

        write_lock_bh(&ls->ls_masters_lock);
        list_for_each_entry_safe(r, safe, &ls->ls_masters_list, res_masters_list) {
                list_del_init(&r->res_masters_list);
                dlm_put_rsb(r);
        }
        write_unlock_bh(&ls->ls_masters_lock);
}

static void dlm_create_root_list(struct dlm_ls *ls, struct list_head *root_list)
{
        struct dlm_rsb *r;

        read_lock_bh(&ls->ls_rsbtbl_lock);
        list_for_each_entry(r, &ls->ls_slow_active, res_slow_list) {
                list_add(&r->res_root_list, root_list);
                dlm_hold_rsb(r);
        }

        WARN_ON_ONCE(!list_empty(&ls->ls_slow_inactive));
        read_unlock_bh(&ls->ls_rsbtbl_lock);
}

static void dlm_release_root_list(struct list_head *root_list)
{
        struct dlm_rsb *r, *safe;

        list_for_each_entry_safe(r, safe, root_list, res_root_list) {
                list_del_init(&r->res_root_list);
                dlm_put_rsb(r);
        }
}

/* If the start for which we're re-enabling locking (seq) has been superseded
   by a newer stop (ls_recover_seq), we need to leave locking disabled.

   We suspend dlm_recv threads here to avoid the race where dlm_recv a) sees
   locking stopped and b) adds a message to the requestqueue, but dlm_recoverd
   enables locking and clears the requestqueue between a and b. */

static int enable_locking(struct dlm_ls *ls, uint64_t seq)
{
        int error = -EINTR;

        write_lock_bh(&ls->ls_recv_active);

        spin_lock_bh(&ls->ls_recover_lock);
        if (ls->ls_recover_seq == seq) {
                set_bit(LSFL_RUNNING, &ls->ls_flags);
                /* Schedule next timer if recovery put something on inactive.
                 *
                 * The rsbs that was queued while recovery on toss hasn't
                 * started yet because LSFL_RUNNING was set everything
                 * else recovery hasn't started as well because ls_in_recovery
                 * is still hold. So we should not run into the case that
                 * resume_scan_timer() queues a timer that can occur in
                 * a no op.
                 */
                resume_scan_timer(ls);
                /* unblocks processes waiting to enter the dlm */
                up_write(&ls->ls_in_recovery);
                clear_bit(LSFL_RECOVER_LOCK, &ls->ls_flags);
                error = 0;
        }
        spin_unlock_bh(&ls->ls_recover_lock);

        write_unlock_bh(&ls->ls_recv_active);
        return error;
}

static int ls_recover(struct dlm_ls *ls, struct dlm_recover *rv)
{
        LIST_HEAD(root_list);
        unsigned long start;
        int error, neg = 0;

        log_rinfo(ls, "dlm_recover %llu", (unsigned long long)rv->seq);

        mutex_lock(&ls->ls_recoverd_active);

        dlm_callback_suspend(ls);

        dlm_clear_inactive(ls);

        /*
         * This list of root rsb's will be the basis of most of the recovery
         * routines.
         */

        dlm_create_root_list(ls, &root_list);

        /*
         * Add or remove nodes from the lockspace's ls_nodes list.
         *
         * Due to the fact that we must report all membership changes to lsops
         * or midcomms layer, it is not permitted to abort ls_recover() until
         * this is done.
         */

        error = dlm_recover_members(ls, rv, &neg);
        if (error) {
                log_rinfo(ls, "dlm_recover_members error %d", error);
                goto fail_root_list;
        }

        dlm_recover_dir_nodeid(ls, &root_list);

        /* Create a snapshot of all active rsbs were we are the master of.
         * During the barrier between dlm_recover_members_wait() and
         * dlm_recover_directory() other nodes can dump their necessary
         * directory dlm_rsb (r->res_dir_nodeid == nodeid) in rcom
         * communication dlm_copy_master_names() handling.
         *
         * TODO We should create a per lockspace list that contains rsbs
         * that we are the master of. Instead of creating this list while
         * recovery we keep track of those rsbs while locking handling and
         * recovery can use it when necessary.
         */
        error = dlm_create_masters_list(ls);
        if (error) {
                log_rinfo(ls, "dlm_create_masters_list error %d", error);
                goto fail_root_list;
        }

        ls->ls_recover_locks_in = 0;

        dlm_set_recover_status(ls, DLM_RS_NODES);

        error = dlm_recover_members_wait(ls, rv->seq);
        if (error) {
                log_rinfo(ls, "dlm_recover_members_wait error %d", error);
                dlm_release_masters_list(ls);
                goto fail_root_list;
        }

        start = jiffies;

        /*
         * Rebuild our own share of the directory by collecting from all other
         * nodes their master rsb names that hash to us.
         */

        error = dlm_recover_directory(ls, rv->seq);
        if (error) {
                log_rinfo(ls, "dlm_recover_directory error %d", error);
                dlm_release_masters_list(ls);
                goto fail_root_list;
        }

        dlm_set_recover_status(ls, DLM_RS_DIR);

        error = dlm_recover_directory_wait(ls, rv->seq);
        if (error) {
                log_rinfo(ls, "dlm_recover_directory_wait error %d", error);
                dlm_release_masters_list(ls);
                goto fail_root_list;
        }

        dlm_release_masters_list(ls);

        /*
         * We may have outstanding operations that are waiting for a reply from
         * a failed node.  Mark these to be resent after recovery.  Unlock and
         * cancel ops can just be completed.
         */

        dlm_recover_waiters_pre(ls);

        if (dlm_recovery_stopped(ls)) {
                error = -EINTR;
                goto fail_root_list;
        }

        if (neg || dlm_no_directory(ls)) {
                /*
                 * Clear lkb's for departed nodes.
                 */

                dlm_recover_purge(ls, &root_list);

                /*
                 * Get new master nodeid's for rsb's that were mastered on
                 * departed nodes.
                 */

                error = dlm_recover_masters(ls, rv->seq, &root_list);
                if (error) {
                        log_rinfo(ls, "dlm_recover_masters error %d", error);
                        goto fail_root_list;
                }

                /*
                 * Send our locks on remastered rsb's to the new masters.
                 */

                error = dlm_recover_locks(ls, rv->seq, &root_list);
                if (error) {
                        log_rinfo(ls, "dlm_recover_locks error %d", error);
                        goto fail_root_list;
                }

                dlm_set_recover_status(ls, DLM_RS_LOCKS);

                error = dlm_recover_locks_wait(ls, rv->seq);
                if (error) {
                        log_rinfo(ls, "dlm_recover_locks_wait error %d", error);
                        goto fail_root_list;
                }

                log_rinfo(ls, "dlm_recover_locks %u in",
                          ls->ls_recover_locks_in);

                /*
                 * Finalize state in master rsb's now that all locks can be
                 * checked.  This includes conversion resolution and lvb
                 * settings.
                 */

                dlm_recover_rsbs(ls, &root_list);
        } else {
                /*
                 * Other lockspace members may be going through the "neg" steps
                 * while also adding us to the lockspace, in which case they'll
                 * be doing the recover_locks (RS_LOCKS) barrier.
                 */
                dlm_set_recover_status(ls, DLM_RS_LOCKS);

                error = dlm_recover_locks_wait(ls, rv->seq);
                if (error) {
                        log_rinfo(ls, "dlm_recover_locks_wait error %d", error);
                        goto fail_root_list;
                }
        }

        dlm_release_root_list(&root_list);

        /*
         * Purge directory-related requests that are saved in requestqueue.
         * All dir requests from before recovery are invalid now due to the dir
         * rebuild and will be resent by the requesting nodes.
         */

        dlm_purge_requestqueue(ls);

        dlm_set_recover_status(ls, DLM_RS_DONE);

        error = dlm_recover_done_wait(ls, rv->seq);
        if (error) {
                log_rinfo(ls, "dlm_recover_done_wait error %d", error);
                goto fail;
        }

        dlm_clear_members_gone(ls);

        dlm_callback_resume(ls);

        error = enable_locking(ls, rv->seq);
        if (error) {
                log_rinfo(ls, "enable_locking error %d", error);
                goto fail;
        }

        error = dlm_process_requestqueue(ls);
        if (error) {
                log_rinfo(ls, "dlm_process_requestqueue error %d", error);
                goto fail;
        }

        error = dlm_recover_waiters_post(ls);
        if (error) {
                log_rinfo(ls, "dlm_recover_waiters_post error %d", error);
                goto fail;
        }

        dlm_recover_grant(ls);

        log_rinfo(ls, "dlm_recover %llu generation %u done: %u ms",
                  (unsigned long long)rv->seq, ls->ls_generation,
                  jiffies_to_msecs(jiffies - start));
        mutex_unlock(&ls->ls_recoverd_active);

        return 0;

 fail_root_list:
        dlm_release_root_list(&root_list);
 fail:
        mutex_unlock(&ls->ls_recoverd_active);

        return error;
}

/* The dlm_ls_start() that created the rv we take here may already have been
   stopped via dlm_ls_stop(); in that case we need to leave the RECOVERY_STOP
   flag set. */

static void do_ls_recovery(struct dlm_ls *ls)
{
        struct dlm_recover *rv = NULL;
        int error;

        spin_lock_bh(&ls->ls_recover_lock);
        rv = ls->ls_recover_args;
        ls->ls_recover_args = NULL;
        if (rv && ls->ls_recover_seq == rv->seq)
                clear_bit(LSFL_RECOVER_STOP, &ls->ls_flags);
        spin_unlock_bh(&ls->ls_recover_lock);

        if (rv) {
                error = ls_recover(ls, rv);
                switch (error) {
                case 0:
                        ls->ls_recovery_result = 0;
                        complete(&ls->ls_recovery_done);

                        dlm_lsop_recover_done(ls);
                        break;
                case -EINTR:
                        /* if recovery was interrupted -EINTR we wait for the next
                         * ls_recover() iteration until it hopefully succeeds.
                         */
                        log_rinfo(ls, "%s %llu interrupted and should be queued to run again",
                                  __func__, (unsigned long long)rv->seq);
                        break;
                default:
                        log_rinfo(ls, "%s %llu error %d", __func__,
                                  (unsigned long long)rv->seq, error);

                        /* let new_lockspace() get aware of critical error */
                        ls->ls_recovery_result = error;
                        complete(&ls->ls_recovery_done);
                        break;
                }

                kfree(rv->nodes);
                kfree(rv);
        }
}

static int dlm_recoverd(void *arg)
{
        struct dlm_ls *ls;

        ls = dlm_find_lockspace_local(arg);
        if (!ls) {
                log_print("dlm_recoverd: no lockspace %p", arg);
                return -1;
        }

        down_write(&ls->ls_in_recovery);
        set_bit(LSFL_RECOVER_LOCK, &ls->ls_flags);
        wake_up(&ls->ls_recover_lock_wait);

        while (1) {
                /*
                 * We call kthread_should_stop() after set_current_state().
                 * This is because it works correctly if kthread_stop() is
                 * called just before set_current_state().
                 */
                set_current_state(TASK_INTERRUPTIBLE);
                if (kthread_should_stop()) {
                        set_current_state(TASK_RUNNING);
                        break;
                }
                if (!test_bit(LSFL_RECOVER_WORK, &ls->ls_flags) &&
                    !test_bit(LSFL_RECOVER_DOWN, &ls->ls_flags)) {
                        if (kthread_should_stop())
                                break;
                        schedule();
                }
                set_current_state(TASK_RUNNING);

                if (test_and_clear_bit(LSFL_RECOVER_DOWN, &ls->ls_flags)) {
                        down_write(&ls->ls_in_recovery);
                        set_bit(LSFL_RECOVER_LOCK, &ls->ls_flags);
                        wake_up(&ls->ls_recover_lock_wait);
                }

                if (test_and_clear_bit(LSFL_RECOVER_WORK, &ls->ls_flags))
                        do_ls_recovery(ls);
        }

        if (test_bit(LSFL_RECOVER_LOCK, &ls->ls_flags))
                up_write(&ls->ls_in_recovery);

        dlm_put_lockspace(ls);
        return 0;
}

int dlm_recoverd_start(struct dlm_ls *ls)
{
        struct task_struct *p;
        int error = 0;

        p = kthread_run(dlm_recoverd, ls, "dlm_recoverd");
        if (IS_ERR(p))
                error = PTR_ERR(p);
        else
                ls->ls_recoverd_task = p;
        return error;
}

void dlm_recoverd_stop(struct dlm_ls *ls)
{
        kthread_stop(ls->ls_recoverd_task);
}

void dlm_recoverd_suspend(struct dlm_ls *ls)
{
        wake_up(&ls->ls_wait_general);
        mutex_lock(&ls->ls_recoverd_active);
}

void dlm_recoverd_resume(struct dlm_ls *ls)
{
        mutex_unlock(&ls->ls_recoverd_active);
}