root/fs/dlm/requestqueue.c

DEFINITIONS

1. dlm_add_requestqueue
2. dlm_process_requestqueue
3. dlm_wait_requestqueue
4. purge_request
5. dlm_purge_requestqueue

/******************************************************************************
*******************************************************************************
**
**  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;
        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_KERNEL);
        if (!e) {
                log_print("dlm_add_requestqueue: out of memory len %d", length);
                return;
        }

        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;
        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);

                dlm_receive_message_saved(ls, &e->request);

                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;

        /* with no directory, the master is likely to change as a part of
           recovery; requests to/from the defunct master need to be purged */

        switch (type) {
        case DLM_MSG_REQUEST:
        case DLM_MSG_CONVERT:
        case DLM_MSG_UNLOCK:
        case DLM_MSG_CANCEL:
                /* we're no longer the master of this resource, the sender
                   will resend to the new master (see waiter_needs_recovery) */

                if (dlm_hash2nodeid(ls, ms->m_hash) != dlm_our_nodeid())
                        return 1;
                break;

        case DLM_MSG_REQUEST_REPLY:
        case DLM_MSG_CONVERT_REPLY:
        case DLM_MSG_UNLOCK_REPLY:
        case DLM_MSG_CANCEL_REPLY:
        case DLM_MSG_GRANT:
                /* this reply is from the former master of the resource,
                   we'll resend to the new master if needed */

                if (dlm_hash2nodeid(ls, ms->m_hash) != nodeid)
                        return 1;
                break;
        }

        return 0;
}

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);
}