ast.c

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/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2010 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 "lock.h"
#include "user.h"

static uint64_t dlm_cb_seq;
static DEFINE_SPINLOCK(dlm_cb_seq_spin);

static void dlm_dump_lkb_callbacks(struct dlm_lkb *lkb)
{
    int i;

    log_print("last_bast %x %llu flags %x mode %d sb %d %x",
          lkb->lkb_id,
          (unsigned long long)lkb->lkb_last_bast.seq,
          lkb->lkb_last_bast.flags,
          lkb->lkb_last_bast.mode,
          lkb->lkb_last_bast.sb_status,
          lkb->lkb_last_bast.sb_flags);

    log_print("last_cast %x %llu flags %x mode %d sb %d %x",
          lkb->lkb_id,
          (unsigned long long)lkb->lkb_last_cast.seq,
          lkb->lkb_last_cast.flags,
          lkb->lkb_last_cast.mode,
          lkb->lkb_last_cast.sb_status,
          lkb->lkb_last_cast.sb_flags);

    for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
        log_print("cb %x %llu flags %x mode %d sb %d %x",
              lkb->lkb_id,
              (unsigned long long)lkb->lkb_callbacks[i].seq,
              lkb->lkb_callbacks[i].flags,
              lkb->lkb_callbacks[i].mode,
              lkb->lkb_callbacks[i].sb_status,
              lkb->lkb_callbacks[i].sb_flags);
    }
}

int dlm_add_lkb_callback(struct dlm_lkb *lkb, uint32_t flags, int mode,
             int status, uint32_t sbflags, uint64_t seq)
{
    struct dlm_ls *ls = lkb->lkb_resource->res_ls;
    uint64_t prev_seq;
    int prev_mode;
    int i, rv;

    for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
        if (lkb->lkb_callbacks[i].seq)
            continue;

        /*
         * Suppress some redundant basts here, do more on removal.
         * Don't even add a bast if the callback just before it
         * is a bast for the same mode or a more restrictive mode.
         * (the addional > PR check is needed for PR/CW inversion)
         */

        if ((i > 0) && (flags & DLM_CB_BAST) &&
            (lkb->lkb_callbacks[i-1].flags & DLM_CB_BAST)) {

            prev_seq = lkb->lkb_callbacks[i-1].seq;
            prev_mode = lkb->lkb_callbacks[i-1].mode;

            if ((prev_mode == mode) ||
                (prev_mode > mode && prev_mode > DLM_LOCK_PR)) {

                log_debug(ls, "skip %x add bast %llu mode %d "
                      "for bast %llu mode %d",
                      lkb->lkb_id,
                      (unsigned long long)seq,
                      mode,
                      (unsigned long long)prev_seq,
                      prev_mode);
                rv = 0;
                goto out;
            }
        }

        lkb->lkb_callbacks[i].seq = seq;
        lkb->lkb_callbacks[i].flags = flags;
        lkb->lkb_callbacks[i].mode = mode;
        lkb->lkb_callbacks[i].sb_status = status;
        lkb->lkb_callbacks[i].sb_flags = (sbflags & 0x000000FF);
        rv = 0;
        break;
    }

    if (i == DLM_CALLBACKS_SIZE) {
        log_error(ls, "no callbacks %x %llu flags %x mode %d sb %d %x",
              lkb->lkb_id, (unsigned long long)seq,
              flags, mode, status, sbflags);
        dlm_dump_lkb_callbacks(lkb);
        rv = -1;
        goto out;
    }
 out:
    return rv;
}

int dlm_rem_lkb_callback(struct dlm_ls *ls, struct dlm_lkb *lkb,
             struct dlm_callback *cb, int *resid)
{
    int i, rv;

    *resid = 0;

    if (!lkb->lkb_callbacks[0].seq) {
        rv = -ENOENT;
        goto out;
    }

    /* oldest undelivered cb is callbacks[0] */

    memcpy(cb, &lkb->lkb_callbacks[0], sizeof(struct dlm_callback));
    memset(&lkb->lkb_callbacks[0], 0, sizeof(struct dlm_callback));

    /* shift others down */

    for (i = 1; i < DLM_CALLBACKS_SIZE; i++) {
        if (!lkb->lkb_callbacks[i].seq)
            break;
        memcpy(&lkb->lkb_callbacks[i-1], &lkb->lkb_callbacks[i],
               sizeof(struct dlm_callback));
        memset(&lkb->lkb_callbacks[i], 0, sizeof(struct dlm_callback));
        (*resid)++;
    }

    /* if cb is a bast, it should be skipped if the blocking mode is
       compatible with the last granted mode */

    if ((cb->flags & DLM_CB_BAST) && lkb->lkb_last_cast.seq) {
        if (dlm_modes_compat(cb->mode, lkb->lkb_last_cast.mode)) {
            cb->flags |= DLM_CB_SKIP;

            log_debug(ls, "skip %x bast %llu mode %d "
                  "for cast %llu mode %d",
                  lkb->lkb_id,
                  (unsigned long long)cb->seq,
                  cb->mode,
                  (unsigned long long)lkb->lkb_last_cast.seq,
                  lkb->lkb_last_cast.mode);
            rv = 0;
            goto out;
        }
    }

    if (cb->flags & DLM_CB_CAST) {
        memcpy(&lkb->lkb_last_cast, cb, sizeof(struct dlm_callback));
        lkb->lkb_last_cast_time = ktime_get();
    }

    if (cb->flags & DLM_CB_BAST) {
        memcpy(&lkb->lkb_last_bast, cb, sizeof(struct dlm_callback));
        lkb->lkb_last_bast_time = ktime_get();
    }
    rv = 0;
 out:
    return rv;
}

void dlm_add_cb(struct dlm_lkb *lkb, uint32_t flags, int mode, int status,
        uint32_t sbflags)
{
    struct dlm_ls *ls = lkb->lkb_resource->res_ls;
    uint64_t new_seq, prev_seq;
    int rv;

    spin_lock(&dlm_cb_seq_spin);
    new_seq = ++dlm_cb_seq;
    spin_unlock(&dlm_cb_seq_spin);

    if (lkb->lkb_flags & DLM_IFL_USER) {
        dlm_user_add_ast(lkb, flags, mode, status, sbflags, new_seq);
        return;
    }

    mutex_lock(&lkb->lkb_cb_mutex);
    prev_seq = lkb->lkb_callbacks[0].seq;

    rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, new_seq);
    if (rv < 0)
        goto out;

    if (!prev_seq) {
        kref_get(&lkb->lkb_ref);

        if (test_bit(LSFL_CB_DELAY, &ls->ls_flags)) {
            mutex_lock(&ls->ls_cb_mutex);
            list_add(&lkb->lkb_cb_list, &ls->ls_cb_delay);
            mutex_unlock(&ls->ls_cb_mutex);
        } else {
            queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
        }
    }
 out:
    mutex_unlock(&lkb->lkb_cb_mutex);
}

void dlm_callback_work(struct work_struct *work)
{
    struct dlm_lkb *lkb = container_of(work, struct dlm_lkb, lkb_cb_work);
    struct dlm_ls *ls = lkb->lkb_resource->res_ls;
    void (*castfn) (void *astparam);
    void (*bastfn) (void *astparam, int mode);
    struct dlm_callback callbacks[DLM_CALLBACKS_SIZE];
    int i, rv, resid;

    memset(&callbacks, 0, sizeof(callbacks));

    mutex_lock(&lkb->lkb_cb_mutex);
    if (!lkb->lkb_callbacks[0].seq) {
        /* no callback work exists, shouldn't happen */
        log_error(ls, "dlm_callback_work %x no work", lkb->lkb_id);
        dlm_print_lkb(lkb);
        dlm_dump_lkb_callbacks(lkb);
    }

    for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
        rv = dlm_rem_lkb_callback(ls, lkb, &callbacks[i], &resid);
        if (rv < 0)
            break;
    }

    if (resid) {
        /* cbs remain, loop should have removed all, shouldn't happen */
        log_error(ls, "dlm_callback_work %x resid %d", lkb->lkb_id,
              resid);
        dlm_print_lkb(lkb);
        dlm_dump_lkb_callbacks(lkb);
    }
    mutex_unlock(&lkb->lkb_cb_mutex);

    castfn = lkb->lkb_astfn;
    bastfn = lkb->lkb_bastfn;

    for (i = 0; i < DLM_CALLBACKS_SIZE; i++) {
        if (!callbacks[i].seq)
            break;
        if (callbacks[i].flags & DLM_CB_SKIP) {
            continue;
        } else if (callbacks[i].flags & DLM_CB_BAST) {
            bastfn(lkb->lkb_astparam, callbacks[i].mode);
        } else if (callbacks[i].flags & DLM_CB_CAST) {
            lkb->lkb_lksb->sb_status = callbacks[i].sb_status;
            lkb->lkb_lksb->sb_flags = callbacks[i].sb_flags;
            castfn(lkb->lkb_astparam);
        }
    }

    /* undo kref_get from dlm_add_callback, may cause lkb to be freed */
    dlm_put_lkb(lkb);
}

int dlm_callback_start(struct dlm_ls *ls)
{
    ls->ls_callback_wq = alloc_workqueue("dlm_callback",
                         WQ_UNBOUND |
                         WQ_MEM_RECLAIM |
                         WQ_NON_REENTRANT,
                         0);
    if (!ls->ls_callback_wq) {
        log_print("can't start dlm_callback workqueue");
        return -ENOMEM;
    }
    return 0;
}

void dlm_callback_stop(struct dlm_ls *ls)
{
    if (ls->ls_callback_wq)
        destroy_workqueue(ls->ls_callback_wq);
}

void dlm_callback_suspend(struct dlm_ls *ls)
{
    set_bit(LSFL_CB_DELAY, &ls->ls_flags);

    if (ls->ls_callback_wq)
        flush_workqueue(ls->ls_callback_wq);
}

void dlm_callback_resume(struct dlm_ls *ls)
{
    struct dlm_lkb *lkb, *safe;
    int count = 0;

    clear_bit(LSFL_CB_DELAY, &ls->ls_flags);

    if (!ls->ls_callback_wq)
        return;

    mutex_lock(&ls->ls_cb_mutex);
    list_for_each_entry_safe(lkb, safe, &ls->ls_cb_delay, lkb_cb_list) {
        list_del_init(&lkb->lkb_cb_list);
        queue_work(ls->ls_callback_wq, &lkb->lkb_cb_work);
        count++;
    }
    mutex_unlock(&ls->ls_cb_mutex);

    if (count)
        log_debug(ls, "dlm_callback_resume %d", count);
}