[deliverable/linux.git] / fs / dlm / recover.c

/******************************************************************************
*******************************************************************************
**
**  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
**  Copyright (C) 2004-2005 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 "lockspace.h"
#include "dir.h"
#include "config.h"
#include "ast.h"
#include "memory.h"
#include "rcom.h"
#include "lock.h"
#include "lowcomms.h"
#include "member.h"
#include "recover.h"


/*
 * Recovery waiting routines: these functions wait for a particular reply from
 * a remote node, or for the remote node to report a certain status.  They need
 * to abort if the lockspace is stopped indicating a node has failed (perhaps
 * the one being waited for).
 */

/*
 * Wait until given function returns non-zero or lockspace is stopped
 * (LS_RECOVERY_STOP set due to failure of a node in ls_nodes).  When another
 * function thinks it could have completed the waited-on task, they should wake
 * up ls_wait_general to get an immediate response rather than waiting for the
 * timer to detect the result.  A timer wakes us up periodically while waiting
 * to see if we should abort due to a node failure.  This should only be called
 * by the dlm_recoverd thread.
 */

static void dlm_wait_timer_fn(unsigned long data)
{
        struct dlm_ls *ls = (struct dlm_ls *) data;
        mod_timer(&ls->ls_timer, jiffies + (dlm_config.ci_recover_timer * HZ));
        wake_up(&ls->ls_wait_general);
}

int dlm_wait_function(struct dlm_ls *ls, int (*testfn) (struct dlm_ls *ls))
{
        int error = 0;

        init_timer(&ls->ls_timer);
        ls->ls_timer.function = dlm_wait_timer_fn;
        ls->ls_timer.data = (long) ls;
        ls->ls_timer.expires = jiffies + (dlm_config.ci_recover_timer * HZ);
        add_timer(&ls->ls_timer);

        wait_event(ls->ls_wait_general, testfn(ls) || dlm_recovery_stopped(ls));
        del_timer_sync(&ls->ls_timer);

        if (dlm_recovery_stopped(ls)) {
                log_debug(ls, "dlm_wait_function aborted");
                error = -EINTR;
        }
        return error;
}

/*
 * An efficient way for all nodes to wait for all others to have a certain
 * status.  The node with the lowest nodeid polls all the others for their
 * status (wait_status_all) and all the others poll the node with the low id
 * for its accumulated result (wait_status_low).  When all nodes have set
 * status flag X, then status flag X_ALL will be set on the low nodeid.
 */

uint32_t dlm_recover_status(struct dlm_ls *ls)
{
        uint32_t status;
        spin_lock(&ls->ls_recover_lock);
        status = ls->ls_recover_status;
        spin_unlock(&ls->ls_recover_lock);
        return status;
}

static void _set_recover_status(struct dlm_ls *ls, uint32_t status)
{
        ls->ls_recover_status |= status;
}

void dlm_set_recover_status(struct dlm_ls *ls, uint32_t status)
{
        spin_lock(&ls->ls_recover_lock);
        _set_recover_status(ls, status);
        spin_unlock(&ls->ls_recover_lock);
}

static int wait_status_all(struct dlm_ls *ls, uint32_t wait_status,
                           int save_slots)
{
        struct dlm_rcom *rc = ls->ls_recover_buf;
        struct dlm_member *memb;
        int error = 0, delay;

        list_for_each_entry(memb, &ls->ls_nodes, list) {
                delay = 0;
                for (;;) {
                        if (dlm_recovery_stopped(ls)) {
                                error = -EINTR;
                                goto out;
                        }

                        error = dlm_rcom_status(ls, memb->nodeid, 0);
                        if (error)
                                goto out;

                        if (save_slots)
                                dlm_slot_save(ls, rc, memb);

                        if (rc->rc_result & wait_status)
                                break;
                        if (delay < 1000)
                                delay += 20;
                        msleep(delay);
                }
        }
 out:
        return error;
}

static int wait_status_low(struct dlm_ls *ls, uint32_t wait_status,
                           uint32_t status_flags)
{
        struct dlm_rcom *rc = ls->ls_recover_buf;
        int error = 0, delay = 0, nodeid = ls->ls_low_nodeid;

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

                error = dlm_rcom_status(ls, nodeid, status_flags);
                if (error)
                        break;

                if (rc->rc_result & wait_status)
                        break;
                if (delay < 1000)
                        delay += 20;
                msleep(delay);
        }
 out:
        return error;
}

static int wait_status(struct dlm_ls *ls, uint32_t status)
{
        uint32_t status_all = status << 1;
        int error;

        if (ls->ls_low_nodeid == dlm_our_nodeid()) {
                error = wait_status_all(ls, status, 0);
                if (!error)
                        dlm_set_recover_status(ls, status_all);
        } else
                error = wait_status_low(ls, status_all, 0);

        return error;
}

int dlm_recover_members_wait(struct dlm_ls *ls)
{
        struct dlm_member *memb;
        struct dlm_slot *slots;
        int num_slots, slots_size;
        int error, rv;
        uint32_t gen;

        list_for_each_entry(memb, &ls->ls_nodes, list) {
                memb->slot = -1;
                memb->generation = 0;
        }

        if (ls->ls_low_nodeid == dlm_our_nodeid()) {
                error = wait_status_all(ls, DLM_RS_NODES, 1);
                if (error)
                        goto out;

                /* slots array is sparse, slots_size may be > num_slots */

                rv = dlm_slots_assign(ls, &num_slots, &slots_size, &slots, &gen);
                if (!rv) {
                        spin_lock(&ls->ls_recover_lock);
                        _set_recover_status(ls, DLM_RS_NODES_ALL);
                        ls->ls_num_slots = num_slots;
                        ls->ls_slots_size = slots_size;
                        ls->ls_slots = slots;
                        ls->ls_generation = gen;
                        spin_unlock(&ls->ls_recover_lock);
                } else {
                        dlm_set_recover_status(ls, DLM_RS_NODES_ALL);
                }
        } else {
                error = wait_status_low(ls, DLM_RS_NODES_ALL, DLM_RSF_NEED_SLOTS);
                if (error)
                        goto out;

                dlm_slots_copy_in(ls);
        }
 out:
        return error;
}

int dlm_recover_directory_wait(struct dlm_ls *ls)
{
        return wait_status(ls, DLM_RS_DIR);
}

int dlm_recover_locks_wait(struct dlm_ls *ls)
{
        return wait_status(ls, DLM_RS_LOCKS);
}

int dlm_recover_done_wait(struct dlm_ls *ls)
{
        return wait_status(ls, DLM_RS_DONE);
}

/*
 * The recover_list contains all the rsb's for which we've requested the new
 * master nodeid.  As replies are returned from the resource directories the
 * rsb's are removed from the list.  When the list is empty we're done.
 *
 * The recover_list is later similarly used for all rsb's for which we've sent
 * new lkb's and need to receive new corresponding lkid's.
 *
 * We use the address of the rsb struct as a simple local identifier for the
 * rsb so we can match an rcom reply with the rsb it was sent for.
 */

static int recover_list_empty(struct dlm_ls *ls)
{
        int empty;

        spin_lock(&ls->ls_recover_list_lock);
        empty = list_empty(&ls->ls_recover_list);
        spin_unlock(&ls->ls_recover_list_lock);

        return empty;
}

static void recover_list_add(struct dlm_rsb *r)
{
        struct dlm_ls *ls = r->res_ls;

        spin_lock(&ls->ls_recover_list_lock);
        if (list_empty(&r->res_recover_list)) {
                list_add_tail(&r->res_recover_list, &ls->ls_recover_list);
                ls->ls_recover_list_count++;
                dlm_hold_rsb(r);
        }
        spin_unlock(&ls->ls_recover_list_lock);
}

static void recover_list_del(struct dlm_rsb *r)
{
        struct dlm_ls *ls = r->res_ls;

        spin_lock(&ls->ls_recover_list_lock);
        list_del_init(&r->res_recover_list);
        ls->ls_recover_list_count--;
        spin_unlock(&ls->ls_recover_list_lock);

        dlm_put_rsb(r);
}

static struct dlm_rsb *recover_list_find(struct dlm_ls *ls, uint64_t id)
{
        struct dlm_rsb *r = NULL;

        spin_lock(&ls->ls_recover_list_lock);

        list_for_each_entry(r, &ls->ls_recover_list, res_recover_list) {
                if (id == (unsigned long) r)
                        goto out;
        }
        r = NULL;
 out:
        spin_unlock(&ls->ls_recover_list_lock);
        return r;
}

static void recover_list_clear(struct dlm_ls *ls)
{
        struct dlm_rsb *r, *s;

        spin_lock(&ls->ls_recover_list_lock);
        list_for_each_entry_safe(r, s, &ls->ls_recover_list, res_recover_list) {
                list_del_init(&r->res_recover_list);
                r->res_recover_locks_count = 0;
                dlm_put_rsb(r);
                ls->ls_recover_list_count--;
        }

        if (ls->ls_recover_list_count != 0) {
                log_error(ls, "warning: recover_list_count %d",
                          ls->ls_recover_list_count);
                ls->ls_recover_list_count = 0;
        }
        spin_unlock(&ls->ls_recover_list_lock);
}


/* Master recovery: find new master node for rsb's that were
   mastered on nodes that have been removed.

   dlm_recover_masters
   recover_master
   dlm_send_rcom_lookup            ->  receive_rcom_lookup
                                       dlm_dir_lookup
   receive_rcom_lookup_reply       <-
   dlm_recover_master_reply
   set_new_master
   set_master_lkbs
   set_lock_master
*/

/*
 * Set the lock master for all LKBs in a lock queue
 * If we are the new master of the rsb, we may have received new
 * MSTCPY locks from other nodes already which we need to ignore
 * when setting the new nodeid.
 */

static void set_lock_master(struct list_head *queue, int nodeid)
{
        struct dlm_lkb *lkb;

        list_for_each_entry(lkb, queue, lkb_statequeue) {
                if (!(lkb->lkb_flags & DLM_IFL_MSTCPY)) {
                        lkb->lkb_nodeid = nodeid;
                        lkb->lkb_remid = 0;
                }
        }
}

static void set_master_lkbs(struct dlm_rsb *r)
{
        set_lock_master(&r->res_grantqueue, r->res_nodeid);
        set_lock_master(&r->res_convertqueue, r->res_nodeid);
        set_lock_master(&r->res_waitqueue, r->res_nodeid);
}

/*
 * Propagate the new master nodeid to locks
 * The NEW_MASTER flag tells dlm_recover_locks() which rsb's to consider.
 * The NEW_MASTER2 flag tells recover_lvb() and recover_grant() which
 * rsb's to consider.
 */

static void set_new_master(struct dlm_rsb *r, int nodeid)
{
        r->res_nodeid = nodeid;
        set_master_lkbs(r);
        rsb_set_flag(r, RSB_NEW_MASTER);
        rsb_set_flag(r, RSB_NEW_MASTER2);
}

/*
 * We do async lookups on rsb's that need new masters.  The rsb's
 * waiting for a lookup reply are kept on the recover_list.
 */

static int recover_master(struct dlm_rsb *r)
{
        struct dlm_ls *ls = r->res_ls;
        int error, ret_nodeid;
        int our_nodeid = dlm_our_nodeid();
        int dir_nodeid = dlm_dir_nodeid(r);

        if (dir_nodeid == our_nodeid) {
                error = dlm_dir_lookup(ls, our_nodeid, r->res_name,
                                       r->res_length, &ret_nodeid);
                if (error)
                        log_error(ls, "recover dir lookup error %d", error);

                if (ret_nodeid == our_nodeid)
                        ret_nodeid = 0;
                lock_rsb(r);
                set_new_master(r, ret_nodeid);
                unlock_rsb(r);
        } else {
                recover_list_add(r);
                error = dlm_send_rcom_lookup(r, dir_nodeid);
        }

        return error;
}

/*
 * All MSTCPY locks are purged and rebuilt, even if the master stayed the same.
 * This is necessary because recovery can be started, aborted and restarted,
 * causing the master nodeid to briefly change during the aborted recovery, and
 * change back to the original value in the second recovery.  The MSTCPY locks
 * may or may not have been purged during the aborted recovery.  Another node
 * with an outstanding request in waiters list and a request reply saved in the
 * requestqueue, cannot know whether it should ignore the reply and resend the
 * request, or accept the reply and complete the request.  It must do the
 * former if the remote node purged MSTCPY locks, and it must do the later if
 * the remote node did not.  This is solved by always purging MSTCPY locks, in
 * which case, the request reply would always be ignored and the request
 * resent.
 */

static int recover_master_static(struct dlm_rsb *r)
{
        int dir_nodeid = dlm_dir_nodeid(r);
        int new_master = dir_nodeid;

        if (dir_nodeid == dlm_our_nodeid())
                new_master = 0;

        lock_rsb(r);
        dlm_purge_mstcpy_locks(r);
        set_new_master(r, new_master);
        unlock_rsb(r);
        return 1;
}

/*
 * Go through local root resources and for each rsb which has a master which
 * has departed, get the new master nodeid from the directory.  The dir will
 * assign mastery to the first node to look up the new master.  That means
 * we'll discover in this lookup if we're the new master of any rsb's.
 *
 * We fire off all the dir lookup requests individually and asynchronously to
 * the correct dir node.
 */

int dlm_recover_masters(struct dlm_ls *ls)
{
        struct dlm_rsb *r;
        int error = 0, count = 0;

        log_debug(ls, "dlm_recover_masters");

        down_read(&ls->ls_root_sem);
        list_for_each_entry(r, &ls->ls_root_list, res_root_list) {
                if (dlm_recovery_stopped(ls)) {
                        up_read(&ls->ls_root_sem);
                        error = -EINTR;
                        goto out;
                }

                if (dlm_no_directory(ls))
                        count += recover_master_static(r);
                else if (!is_master(r) &&
                         (dlm_is_removed(ls, r->res_nodeid) ||
                          rsb_flag(r, RSB_NEW_MASTER))) {
                        recover_master(r);
                        count++;
                }

                schedule();
        }
        up_read(&ls->ls_root_sem);

        log_debug(ls, "dlm_recover_masters %d resources", count);

        error = dlm_wait_function(ls, &recover_list_empty);
 out:
        if (error)
                recover_list_clear(ls);
        return error;
}

int dlm_recover_master_reply(struct dlm_ls *ls, struct dlm_rcom *rc)
{
        struct dlm_rsb *r;
        int nodeid;

        r = recover_list_find(ls, rc->rc_id);
        if (!r) {
                log_error(ls, "dlm_recover_master_reply no id %llx",
                          (unsigned long long)rc->rc_id);
                goto out;
        }

        nodeid = rc->rc_result;
        if (nodeid == dlm_our_nodeid())
                nodeid = 0;

        lock_rsb(r);
        set_new_master(r, nodeid);
        unlock_rsb(r);
        recover_list_del(r);

        if (recover_list_empty(ls))
                wake_up(&ls->ls_wait_general);
 out:
        return 0;
}


/* Lock recovery: rebuild the process-copy locks we hold on a
   remastered rsb on the new rsb master.

   dlm_recover_locks
   recover_locks
   recover_locks_queue
   dlm_send_rcom_lock              ->  receive_rcom_lock
                                       dlm_recover_master_copy
   receive_rcom_lock_reply         <-
   dlm_recover_process_copy
*/


/*
 * keep a count of the number of lkb's we send to the new master; when we get
 * an equal number of replies then recovery for the rsb is done
 */

static int recover_locks_queue(struct dlm_rsb *r, struct list_head *head)
{
        struct dlm_lkb *lkb;
        int error = 0;

        list_for_each_entry(lkb, head, lkb_statequeue) {
                error = dlm_send_rcom_lock(r, lkb);
                if (error)
                        break;
                r->res_recover_locks_count++;
        }

        return error;
}

static int recover_locks(struct dlm_rsb *r)
{
        int error = 0;

        lock_rsb(r);

        DLM_ASSERT(!r->res_recover_locks_count, dlm_dump_rsb(r););

        error = recover_locks_queue(r, &r->res_grantqueue);
        if (error)
                goto out;
        error = recover_locks_queue(r, &r->res_convertqueue);
        if (error)
                goto out;
        error = recover_locks_queue(r, &r->res_waitqueue);
        if (error)
                goto out;

        if (r->res_recover_locks_count)
                recover_list_add(r);
        else
                rsb_clear_flag(r, RSB_NEW_MASTER);
 out:
        unlock_rsb(r);
        return error;
}

int dlm_recover_locks(struct dlm_ls *ls)
{
        struct dlm_rsb *r;
        int error, count = 0;

        down_read(&ls->ls_root_sem);
        list_for_each_entry(r, &ls->ls_root_list, res_root_list) {
                if (is_master(r)) {
                        rsb_clear_flag(r, RSB_NEW_MASTER);
                        continue;
                }

                if (!rsb_flag(r, RSB_NEW_MASTER))
                        continue;

                if (dlm_recovery_stopped(ls)) {
                        error = -EINTR;
                        up_read(&ls->ls_root_sem);
                        goto out;
                }

                error = recover_locks(r);
                if (error) {
                        up_read(&ls->ls_root_sem);
                        goto out;
                }

                count += r->res_recover_locks_count;
        }
        up_read(&ls->ls_root_sem);

        log_debug(ls, "dlm_recover_locks %d out", count);

        error = dlm_wait_function(ls, &recover_list_empty);
 out:
        if (error)
                recover_list_clear(ls);
        return error;
}

void dlm_recovered_lock(struct dlm_rsb *r)
{
        DLM_ASSERT(rsb_flag(r, RSB_NEW_MASTER), dlm_dump_rsb(r););

        r->res_recover_locks_count--;
        if (!r->res_recover_locks_count) {
                rsb_clear_flag(r, RSB_NEW_MASTER);
                recover_list_del(r);
        }

        if (recover_list_empty(r->res_ls))
                wake_up(&r->res_ls->ls_wait_general);
}

/*
 * The lvb needs to be recovered on all master rsb's.  This includes setting
 * the VALNOTVALID flag if necessary, and determining the correct lvb contents
 * based on the lvb's of the locks held on the rsb.
 *
 * RSB_VALNOTVALID is set if there are only NL/CR locks on the rsb.  If it
 * was already set prior to recovery, it's not cleared, regardless of locks.
 *
 * The LVB contents are only considered for changing when this is a new master
 * of the rsb (NEW_MASTER2).  Then, the rsb's lvb is taken from any lkb with
 * mode > CR.  If no lkb's exist with mode above CR, the lvb contents are taken
 * from the lkb with the largest lvb sequence number.
 */

static void recover_lvb(struct dlm_rsb *r)
{
        struct dlm_lkb *lkb, *high_lkb = NULL;
        uint32_t high_seq = 0;
        int lock_lvb_exists = 0;
        int big_lock_exists = 0;
        int lvblen = r->res_ls->ls_lvblen;

        list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
                if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
                        continue;

                lock_lvb_exists = 1;

                if (lkb->lkb_grmode > DLM_LOCK_CR) {
                        big_lock_exists = 1;
                        goto setflag;
                }

                if (((int)lkb->lkb_lvbseq - (int)high_seq) >= 0) {
                        high_lkb = lkb;
                        high_seq = lkb->lkb_lvbseq;
                }
        }

        list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
                if (!(lkb->lkb_exflags & DLM_LKF_VALBLK))
                        continue;

                lock_lvb_exists = 1;

                if (lkb->lkb_grmode > DLM_LOCK_CR) {
                        big_lock_exists = 1;
                        goto setflag;
                }

                if (((int)lkb->lkb_lvbseq - (int)high_seq) >= 0) {
                        high_lkb = lkb;
                        high_seq = lkb->lkb_lvbseq;
                }
        }

 setflag:
        if (!lock_lvb_exists)
                goto out;

        if (!big_lock_exists)
                rsb_set_flag(r, RSB_VALNOTVALID);

        /* don't mess with the lvb unless we're the new master */
        if (!rsb_flag(r, RSB_NEW_MASTER2))
                goto out;

        if (!r->res_lvbptr) {
                r->res_lvbptr = dlm_allocate_lvb(r->res_ls);
                if (!r->res_lvbptr)
                        goto out;
        }

        if (big_lock_exists) {
                r->res_lvbseq = lkb->lkb_lvbseq;
                memcpy(r->res_lvbptr, lkb->lkb_lvbptr, lvblen);
        } else if (high_lkb) {
                r->res_lvbseq = high_lkb->lkb_lvbseq;
                memcpy(r->res_lvbptr, high_lkb->lkb_lvbptr, lvblen);
        } else {
                r->res_lvbseq = 0;
                memset(r->res_lvbptr, 0, lvblen);
        }
 out:
        return;
}

/* All master rsb's flagged RECOVER_CONVERT need to be looked at.  The locks
   converting PR->CW or CW->PR need to have their lkb_grmode set. */

static void recover_conversion(struct dlm_rsb *r)
{
        struct dlm_lkb *lkb;
        int grmode = -1;

        list_for_each_entry(lkb, &r->res_grantqueue, lkb_statequeue) {
                if (lkb->lkb_grmode == DLM_LOCK_PR ||
                    lkb->lkb_grmode == DLM_LOCK_CW) {
                        grmode = lkb->lkb_grmode;
                        break;
                }
        }

        list_for_each_entry(lkb, &r->res_convertqueue, lkb_statequeue) {
                if (lkb->lkb_grmode != DLM_LOCK_IV)
                        continue;
                if (grmode == -1)
                        lkb->lkb_grmode = lkb->lkb_rqmode;
                else
                        lkb->lkb_grmode = grmode;
        }
}

/* We've become the new master for this rsb and waiting/converting locks may
   need to be granted in dlm_recover_grant() due to locks that may have
   existed from a removed node. */

static void recover_grant(struct dlm_rsb *r)
{
        if (!list_empty(&r->res_waitqueue) || !list_empty(&r->res_convertqueue))
                rsb_set_flag(r, RSB_RECOVER_GRANT);
}

void dlm_recover_rsbs(struct dlm_ls *ls)
{
        struct dlm_rsb *r;
        unsigned int count = 0;

        down_read(&ls->ls_root_sem);
        list_for_each_entry(r, &ls->ls_root_list, res_root_list) {
                lock_rsb(r);
                if (is_master(r)) {
                        if (rsb_flag(r, RSB_RECOVER_CONVERT))
                                recover_conversion(r);
                        if (rsb_flag(r, RSB_NEW_MASTER2))
                                recover_grant(r);
                        recover_lvb(r);
                        count++;
                }
                rsb_clear_flag(r, RSB_RECOVER_CONVERT);
                rsb_clear_flag(r, RSB_NEW_MASTER2);
                unlock_rsb(r);
        }
        up_read(&ls->ls_root_sem);

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

/* Create a single list of all root rsb's to be used during recovery */

int dlm_create_root_list(struct dlm_ls *ls)
{
        struct rb_node *n;
        struct dlm_rsb *r;
        int i, error = 0;

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

        for (i = 0; i < ls->ls_rsbtbl_size; i++) {
                spin_lock(&ls->ls_rsbtbl[i].lock);
                for (n = rb_first(&ls->ls_rsbtbl[i].keep); n; n = rb_next(n)) {
                        r = rb_entry(n, struct dlm_rsb, res_hashnode);
                        list_add(&r->res_root_list, &ls->ls_root_list);
                        dlm_hold_rsb(r);
                }

                /* If we're using a directory, add tossed rsbs to the root
                   list; they'll have entries created in the new directory,
                   but no other recovery steps should do anything with them. */

                if (dlm_no_directory(ls)) {
                        spin_unlock(&ls->ls_rsbtbl[i].lock);
                        continue;
                }

                for (n = rb_first(&ls->ls_rsbtbl[i].toss); n; n = rb_next(n)) {
                        r = rb_entry(n, struct dlm_rsb, res_hashnode);
                        list_add(&r->res_root_list, &ls->ls_root_list);
                        dlm_hold_rsb(r);
                }
                spin_unlock(&ls->ls_rsbtbl[i].lock);
        }
 out:
        up_write(&ls->ls_root_sem);
        return error;
}

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

        down_write(&ls->ls_root_sem);
        list_for_each_entry_safe(r, safe, &ls->ls_root_list, res_root_list) {
                list_del_init(&r->res_root_list);
                dlm_put_rsb(r);
        }
        up_write(&ls->ls_root_sem);
}

/* If not using a directory, clear the entire toss list, there's no benefit to
   caching the master value since it's fixed.  If we are using a dir, keep the
   rsb's we're the master of.  Recovery will add them to the root list and from
   there they'll be entered in the rebuilt directory. */

void dlm_clear_toss_list(struct dlm_ls *ls)
{
        struct rb_node *n, *next;
        struct dlm_rsb *rsb;
        int i;

        for (i = 0; i < ls->ls_rsbtbl_size; i++) {
                spin_lock(&ls->ls_rsbtbl[i].lock);
                for (n = rb_first(&ls->ls_rsbtbl[i].toss); n; n = next) {
                        next = rb_next(n);;
                        rsb = rb_entry(n, struct dlm_rsb, res_hashnode);
                        if (dlm_no_directory(ls) || !is_master(rsb)) {
                                rb_erase(n, &ls->ls_rsbtbl[i].toss);
                                dlm_free_rsb(rsb);
                        }
                }
                spin_unlock(&ls->ls_rsbtbl[i].lock);
        }
}