requestqueue.c

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/******************************************************************************
*******************************************************************************
**
**  Copyright (C) 2005-2007 Red Hat, Inc.  All rights reserved.
**
**  This copyrighted material is made available to anyone wishing to use,
**  modify, copy, or redistribute it subject to the terms and conditions
**  of the GNU General Public License v.2.
**
*******************************************************************************
******************************************************************************/

#include "dlm_internal.h"
#include "member.h"
#include "lock.h"
#include "dir.h"
#include "config.h"
#include "requestqueue.h"

struct rq_entry {
    struct list_head list;
    uint32_t recover_seq;
    int nodeid;
    struct dlm_message request;
};

/*
 * Requests received while the lockspace is in recovery get added to the
 * request queue and processed when recovery is complete.  This happens when
 * the lockspace is suspended on some nodes before it is on others, or the
 * lockspace is enabled on some while still suspended on others.
 */

void dlm_add_requestqueue(struct dlm_ls *ls, int nodeid, struct dlm_message *ms)
{
    struct rq_entry *e;
    int length = ms->m_header.h_length - sizeof(struct dlm_message);

    e = kmalloc(sizeof(struct rq_entry) + length, GFP_NOFS);
    if (!e) {
        log_print("dlm_add_requestqueue: out of memory len %d", length);
        return;
    }

    e->recover_seq = ls->ls_recover_seq & 0xFFFFFFFF;
    e->nodeid = nodeid;
    memcpy(&e->request, ms, ms->m_header.h_length);

    mutex_lock(&ls->ls_requestqueue_mutex);
    list_add_tail(&e->list, &ls->ls_requestqueue);
    mutex_unlock(&ls->ls_requestqueue_mutex);
}

/*
 * Called by dlm_recoverd to process normal messages saved while recovery was
 * happening.  Normal locking has been enabled before this is called.  dlm_recv
 * upon receiving a message, will wait for all saved messages to be drained
 * here before processing the message it got.  If a new dlm_ls_stop() arrives
 * while we're processing these saved messages, it may block trying to suspend
 * dlm_recv if dlm_recv is waiting for us in dlm_wait_requestqueue.  In that
 * case, we don't abort since locking_stopped is still 0.  If dlm_recv is not
 * waiting for us, then this processing may be aborted due to locking_stopped.
 */

int dlm_process_requestqueue(struct dlm_ls *ls)
{
    struct rq_entry *e;
    struct dlm_message *ms;
    int error = 0;

    mutex_lock(&ls->ls_requestqueue_mutex);

    for (;;) {
        if (list_empty(&ls->ls_requestqueue)) {
            mutex_unlock(&ls->ls_requestqueue_mutex);
            error = 0;
            break;
        }
        e = list_entry(ls->ls_requestqueue.next, struct rq_entry, list);
        mutex_unlock(&ls->ls_requestqueue_mutex);

        ms = &e->request;

        log_limit(ls, "dlm_process_requestqueue msg %d from %d "
              "lkid %x remid %x result %d seq %u",
              ms->m_type, ms->m_header.h_nodeid,
              ms->m_lkid, ms->m_remid, ms->m_result,
              e->recover_seq);

        dlm_receive_message_saved(ls, &e->request, e->recover_seq);

        mutex_lock(&ls->ls_requestqueue_mutex);
        list_del(&e->list);
        kfree(e);

        if (dlm_locking_stopped(ls)) {
            log_debug(ls, "process_requestqueue abort running");
            mutex_unlock(&ls->ls_requestqueue_mutex);
            error = -EINTR;
            break;
        }
        schedule();
    }

    return error;
}

/*
 * After recovery is done, locking is resumed and dlm_recoverd takes all the
 * saved requests and processes them as they would have been by dlm_recv.  At
 * the same time, dlm_recv will start receiving new requests from remote nodes.
 * We want to delay dlm_recv processing new requests until dlm_recoverd has
 * finished processing the old saved requests.  We don't check for locking
 * stopped here because dlm_ls_stop won't stop locking until it's suspended us
 * (dlm_recv).
 */

void dlm_wait_requestqueue(struct dlm_ls *ls)
{
    for (;;) {
        mutex_lock(&ls->ls_requestqueue_mutex);
        if (list_empty(&ls->ls_requestqueue))
            break;
        mutex_unlock(&ls->ls_requestqueue_mutex);
        schedule();
    }
    mutex_unlock(&ls->ls_requestqueue_mutex);
}

static int purge_request(struct dlm_ls *ls, struct dlm_message *ms, int nodeid)
{
    uint32_t type = ms->m_type;

    /* the ls is being cleaned up and freed by release_lockspace */
    if (!ls->ls_count)
        return 1;

    if (dlm_is_removed(ls, nodeid))
        return 1;

    /* directory operations are always purged because the directory is
       always rebuilt during recovery and the lookups resent */

    if (type == DLM_MSG_REMOVE ||
        type == DLM_MSG_LOOKUP ||
        type == DLM_MSG_LOOKUP_REPLY)
        return 1;

    if (!dlm_no_directory(ls))
        return 0;

    return 1;
}

void dlm_purge_requestqueue(struct dlm_ls *ls)
{
    struct dlm_message *ms;
    struct rq_entry *e, *safe;

    mutex_lock(&ls->ls_requestqueue_mutex);
    list_for_each_entry_safe(e, safe, &ls->ls_requestqueue, list) {
        ms =  &e->request;

        if (purge_request(ls, ms, e->nodeid)) {
            list_del(&e->list);
            kfree(e);
        }
    }
    mutex_unlock(&ls->ls_requestqueue_mutex);
}