dlmlock.c

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/* -*- mode: c; c-basic-offset: 8; -*-
 * vim: noexpandtab sw=8 ts=8 sts=0:
 *
 * dlmlock.c
 *
 * underlying calls for lock creation
 *
 * Copyright (C) 2004 Oracle.  All rights reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 021110-1307, USA.
 *
 */


#include <linux/module.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/sysctl.h>
#include <linux/random.h>
#include <linux/blkdev.h>
#include <linux/socket.h>
#include <linux/inet.h>
#include <linux/spinlock.h>
#include <linux/delay.h>


#include "cluster/heartbeat.h"
#include "cluster/nodemanager.h"
#include "cluster/tcp.h"

#include "dlmapi.h"
#include "dlmcommon.h"

#include "dlmconvert.h"

#define MLOG_MASK_PREFIX ML_DLM
#include "cluster/masklog.h"

static struct kmem_cache *dlm_lock_cache = NULL;

static DEFINE_SPINLOCK(dlm_cookie_lock);
static u64 dlm_next_cookie = 1;

static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
                           struct dlm_lock_resource *res,
                           struct dlm_lock *lock, int flags);
static void dlm_init_lock(struct dlm_lock *newlock, int type,
              u8 node, u64 cookie);
static void dlm_lock_release(struct kref *kref);
static void dlm_lock_detach_lockres(struct dlm_lock *lock);

int dlm_init_lock_cache(void)
{
    dlm_lock_cache = kmem_cache_create("o2dlm_lock",
                       sizeof(struct dlm_lock),
                       0, SLAB_HWCACHE_ALIGN, NULL);
    if (dlm_lock_cache == NULL)
        return -ENOMEM;
    return 0;
}

void dlm_destroy_lock_cache(void)
{
    if (dlm_lock_cache)
        kmem_cache_destroy(dlm_lock_cache);
}

/* Tell us whether we can grant a new lock request.
 * locking:
 *   caller needs:  res->spinlock
 *   taken:         none
 *   held on exit:  none
 * returns: 1 if the lock can be granted, 0 otherwise.
 */
static int dlm_can_grant_new_lock(struct dlm_lock_resource *res,
                  struct dlm_lock *lock)
{
    struct list_head *iter;
    struct dlm_lock *tmplock;

    list_for_each(iter, &res->granted) {
        tmplock = list_entry(iter, struct dlm_lock, list);

        if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
            return 0;
    }

    list_for_each(iter, &res->converting) {
        tmplock = list_entry(iter, struct dlm_lock, list);

        if (!dlm_lock_compatible(tmplock->ml.type, lock->ml.type))
            return 0;
        if (!dlm_lock_compatible(tmplock->ml.convert_type,
                     lock->ml.type))
            return 0;
    }

    return 1;
}

/* performs lock creation at the lockres master site
 * locking:
 *   caller needs:  none
 *   taken:         takes and drops res->spinlock
 *   held on exit:  none
 * returns: DLM_NORMAL, DLM_NOTQUEUED
 */
static enum dlm_status dlmlock_master(struct dlm_ctxt *dlm,
                      struct dlm_lock_resource *res,
                      struct dlm_lock *lock, int flags)
{
    int call_ast = 0, kick_thread = 0;
    enum dlm_status status = DLM_NORMAL;

    mlog(0, "type=%d\n", lock->ml.type);

    spin_lock(&res->spinlock);
    /* if called from dlm_create_lock_handler, need to
     * ensure it will not sleep in dlm_wait_on_lockres */
    status = __dlm_lockres_state_to_status(res);
    if (status != DLM_NORMAL &&
        lock->ml.node != dlm->node_num) {
        /* erf.  state changed after lock was dropped. */
        spin_unlock(&res->spinlock);
        dlm_error(status);
        return status;
    }
    __dlm_wait_on_lockres(res);
    __dlm_lockres_reserve_ast(res);

    if (dlm_can_grant_new_lock(res, lock)) {
        mlog(0, "I can grant this lock right away\n");
        /* got it right away */
        lock->lksb->status = DLM_NORMAL;
        status = DLM_NORMAL;
        dlm_lock_get(lock);
        list_add_tail(&lock->list, &res->granted);

        /* for the recovery lock, we can't allow the ast
         * to be queued since the dlmthread is already
         * frozen.  but the recovery lock is always locked
         * with LKM_NOQUEUE so we do not need the ast in
         * this special case */
        if (!dlm_is_recovery_lock(res->lockname.name,
                      res->lockname.len)) {
            kick_thread = 1;
            call_ast = 1;
        } else {
            mlog(0, "%s: returning DLM_NORMAL to "
                 "node %u for reco lock\n", dlm->name,
                 lock->ml.node);
        }
    } else {
        /* for NOQUEUE request, unless we get the
         * lock right away, return DLM_NOTQUEUED */
        if (flags & LKM_NOQUEUE) {
            status = DLM_NOTQUEUED;
            if (dlm_is_recovery_lock(res->lockname.name,
                         res->lockname.len)) {
                mlog(0, "%s: returning NOTQUEUED to "
                     "node %u for reco lock\n", dlm->name,
                     lock->ml.node);
            }
        } else {
            dlm_lock_get(lock);
            list_add_tail(&lock->list, &res->blocked);
            kick_thread = 1;
        }
    }

    spin_unlock(&res->spinlock);
    wake_up(&res->wq);

    /* either queue the ast or release it */
    if (call_ast)
        dlm_queue_ast(dlm, lock);
    else
        dlm_lockres_release_ast(dlm, res);

    dlm_lockres_calc_usage(dlm, res);
    if (kick_thread)
        dlm_kick_thread(dlm, res);

    return status;
}

void dlm_revert_pending_lock(struct dlm_lock_resource *res,
                 struct dlm_lock *lock)
{
    /* remove from local queue if it failed */
    list_del_init(&lock->list);
    lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
}


/*
 * locking:
 *   caller needs:  none
 *   taken:         takes and drops res->spinlock
 *   held on exit:  none
 * returns: DLM_DENIED, DLM_RECOVERING, or net status
 */
static enum dlm_status dlmlock_remote(struct dlm_ctxt *dlm,
                      struct dlm_lock_resource *res,
                      struct dlm_lock *lock, int flags)
{
    enum dlm_status status = DLM_DENIED;
    int lockres_changed = 1;

    mlog(0, "type=%d, lockres %.*s, flags = 0x%x\n",
         lock->ml.type, res->lockname.len,
         res->lockname.name, flags);

    /*
     * Wait if resource is getting recovered, remastered, etc.
     * If the resource was remastered and new owner is self, then exit.
     */
    spin_lock(&res->spinlock);
    __dlm_wait_on_lockres(res);
    if (res->owner == dlm->node_num) {
        spin_unlock(&res->spinlock);
        return DLM_RECOVERING;
    }
    res->state |= DLM_LOCK_RES_IN_PROGRESS;

    /* add lock to local (secondary) queue */
    dlm_lock_get(lock);
    list_add_tail(&lock->list, &res->blocked);
    lock->lock_pending = 1;
    spin_unlock(&res->spinlock);

    /* spec seems to say that you will get DLM_NORMAL when the lock
     * has been queued, meaning we need to wait for a reply here. */
    status = dlm_send_remote_lock_request(dlm, res, lock, flags);

    spin_lock(&res->spinlock);
    res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
    lock->lock_pending = 0;
    if (status != DLM_NORMAL) {
        if (status == DLM_RECOVERING &&
            dlm_is_recovery_lock(res->lockname.name,
                     res->lockname.len)) {
            /* recovery lock was mastered by dead node.
             * we need to have calc_usage shoot down this
             * lockres and completely remaster it. */
            mlog(0, "%s: recovery lock was owned by "
                 "dead node %u, remaster it now.\n",
                 dlm->name, res->owner);
        } else if (status != DLM_NOTQUEUED) {
            /*
             * DO NOT call calc_usage, as this would unhash
             * the remote lockres before we ever get to use
             * it.  treat as if we never made any change to
             * the lockres.
             */
            lockres_changed = 0;
            dlm_error(status);
        }
        dlm_revert_pending_lock(res, lock);
        dlm_lock_put(lock);
    } else if (dlm_is_recovery_lock(res->lockname.name,
                    res->lockname.len)) {
        /* special case for the $RECOVERY lock.
         * there will never be an AST delivered to put
         * this lock on the proper secondary queue
         * (granted), so do it manually. */
        mlog(0, "%s: $RECOVERY lock for this node (%u) is "
             "mastered by %u; got lock, manually granting (no ast)\n",
             dlm->name, dlm->node_num, res->owner);
        list_move_tail(&lock->list, &res->granted);
    }
    spin_unlock(&res->spinlock);

    if (lockres_changed)
        dlm_lockres_calc_usage(dlm, res);

    wake_up(&res->wq);
    return status;
}


/* for remote lock creation.
 * locking:
 *   caller needs:  none, but need res->state & DLM_LOCK_RES_IN_PROGRESS
 *   taken:         none
 *   held on exit:  none
 * returns: DLM_NOLOCKMGR, or net status
 */
static enum dlm_status dlm_send_remote_lock_request(struct dlm_ctxt *dlm,
                           struct dlm_lock_resource *res,
                           struct dlm_lock *lock, int flags)
{
    struct dlm_create_lock create;
    int tmpret, status = 0;
    enum dlm_status ret;

    memset(&create, 0, sizeof(create));
    create.node_idx = dlm->node_num;
    create.requested_type = lock->ml.type;
    create.cookie = lock->ml.cookie;
    create.namelen = res->lockname.len;
    create.flags = cpu_to_be32(flags);
    memcpy(create.name, res->lockname.name, create.namelen);

    tmpret = o2net_send_message(DLM_CREATE_LOCK_MSG, dlm->key, &create,
                    sizeof(create), res->owner, &status);
    if (tmpret >= 0) {
        ret = status;
        if (ret == DLM_REJECTED) {
            mlog(ML_ERROR, "%s: res %.*s, Stale lockres no longer "
                 "owned by node %u. That node is coming back up "
                 "currently.\n", dlm->name, create.namelen,
                 create.name, res->owner);
            dlm_print_one_lock_resource(res);
            BUG();
        }
    } else {
        mlog(ML_ERROR, "%s: res %.*s, Error %d send CREATE LOCK to "
             "node %u\n", dlm->name, create.namelen, create.name,
             tmpret, res->owner);
        if (dlm_is_host_down(tmpret))
            ret = DLM_RECOVERING;
        else
            ret = dlm_err_to_dlm_status(tmpret);
    }

    return ret;
}

void dlm_lock_get(struct dlm_lock *lock)
{
    kref_get(&lock->lock_refs);
}

void dlm_lock_put(struct dlm_lock *lock)
{
    kref_put(&lock->lock_refs, dlm_lock_release);
}

static void dlm_lock_release(struct kref *kref)
{
    struct dlm_lock *lock;

    lock = container_of(kref, struct dlm_lock, lock_refs);

    BUG_ON(!list_empty(&lock->list));
    BUG_ON(!list_empty(&lock->ast_list));
    BUG_ON(!list_empty(&lock->bast_list));
    BUG_ON(lock->ast_pending);
    BUG_ON(lock->bast_pending);

    dlm_lock_detach_lockres(lock);

    if (lock->lksb_kernel_allocated) {
        mlog(0, "freeing kernel-allocated lksb\n");
        kfree(lock->lksb);
    }
    kmem_cache_free(dlm_lock_cache, lock);
}

/* associate a lock with it's lockres, getting a ref on the lockres */
void dlm_lock_attach_lockres(struct dlm_lock *lock,
                 struct dlm_lock_resource *res)
{
    dlm_lockres_get(res);
    lock->lockres = res;
}

/* drop ref on lockres, if there is still one associated with lock */
static void dlm_lock_detach_lockres(struct dlm_lock *lock)
{
    struct dlm_lock_resource *res;

    res = lock->lockres;
    if (res) {
        lock->lockres = NULL;
        mlog(0, "removing lock's lockres reference\n");
        dlm_lockres_put(res);
    }
}

static void dlm_init_lock(struct dlm_lock *newlock, int type,
              u8 node, u64 cookie)
{
    INIT_LIST_HEAD(&newlock->list);
    INIT_LIST_HEAD(&newlock->ast_list);
    INIT_LIST_HEAD(&newlock->bast_list);
    spin_lock_init(&newlock->spinlock);
    newlock->ml.type = type;
    newlock->ml.convert_type = LKM_IVMODE;
    newlock->ml.highest_blocked = LKM_IVMODE;
    newlock->ml.node = node;
    newlock->ml.pad1 = 0;
    newlock->ml.list = 0;
    newlock->ml.flags = 0;
    newlock->ast = NULL;
    newlock->bast = NULL;
    newlock->astdata = NULL;
    newlock->ml.cookie = cpu_to_be64(cookie);
    newlock->ast_pending = 0;
    newlock->bast_pending = 0;
    newlock->convert_pending = 0;
    newlock->lock_pending = 0;
    newlock->unlock_pending = 0;
    newlock->cancel_pending = 0;
    newlock->lksb_kernel_allocated = 0;

    kref_init(&newlock->lock_refs);
}

struct dlm_lock * dlm_new_lock(int type, u8 node, u64 cookie,
                   struct dlm_lockstatus *lksb)
{
    struct dlm_lock *lock;
    int kernel_allocated = 0;

    lock = kmem_cache_zalloc(dlm_lock_cache, GFP_NOFS);
    if (!lock)
        return NULL;

    if (!lksb) {
        /* zero memory only if kernel-allocated */
        lksb = kzalloc(sizeof(*lksb), GFP_NOFS);
        if (!lksb) {
            kmem_cache_free(dlm_lock_cache, lock);
            return NULL;
        }
        kernel_allocated = 1;
    }

    dlm_init_lock(lock, type, node, cookie);
    if (kernel_allocated)
        lock->lksb_kernel_allocated = 1;
    lock->lksb = lksb;
    lksb->lockid = lock;
    return lock;
}

/* handler for lock creation net message
 * locking:
 *   caller needs:  none
 *   taken:         takes and drops res->spinlock
 *   held on exit:  none
 * returns: DLM_NORMAL, DLM_SYSERR, DLM_IVLOCKID, DLM_NOTQUEUED
 */
int dlm_create_lock_handler(struct o2net_msg *msg, u32 len, void *data,
                void **ret_data)
{
    struct dlm_ctxt *dlm = data;
    struct dlm_create_lock *create = (struct dlm_create_lock *)msg->buf;
    struct dlm_lock_resource *res = NULL;
    struct dlm_lock *newlock = NULL;
    struct dlm_lockstatus *lksb = NULL;
    enum dlm_status status = DLM_NORMAL;
    char *name;
    unsigned int namelen;

    BUG_ON(!dlm);

    if (!dlm_grab(dlm))
        return DLM_REJECTED;

    name = create->name;
    namelen = create->namelen;
    status = DLM_REJECTED;
    if (!dlm_domain_fully_joined(dlm)) {
        mlog(ML_ERROR, "Domain %s not fully joined, but node %u is "
             "sending a create_lock message for lock %.*s!\n",
             dlm->name, create->node_idx, namelen, name);
        dlm_error(status);
        goto leave;
    }

    status = DLM_IVBUFLEN;
    if (namelen > DLM_LOCKID_NAME_MAX) {
        dlm_error(status);
        goto leave;
    }

    status = DLM_SYSERR;
    newlock = dlm_new_lock(create->requested_type,
                   create->node_idx,
                   be64_to_cpu(create->cookie), NULL);
    if (!newlock) {
        dlm_error(status);
        goto leave;
    }

    lksb = newlock->lksb;

    if (be32_to_cpu(create->flags) & LKM_GET_LVB) {
        lksb->flags |= DLM_LKSB_GET_LVB;
        mlog(0, "set DLM_LKSB_GET_LVB flag\n");
    }

    status = DLM_IVLOCKID;
    res = dlm_lookup_lockres(dlm, name, namelen);
    if (!res) {
        dlm_error(status);
        goto leave;
    }

    spin_lock(&res->spinlock);
    status = __dlm_lockres_state_to_status(res);
    spin_unlock(&res->spinlock);

    if (status != DLM_NORMAL) {
        mlog(0, "lockres recovering/migrating/in-progress\n");
        goto leave;
    }

    dlm_lock_attach_lockres(newlock, res);

    status = dlmlock_master(dlm, res, newlock, be32_to_cpu(create->flags));
leave:
    if (status != DLM_NORMAL)
        if (newlock)
            dlm_lock_put(newlock);

    if (res)
        dlm_lockres_put(res);

    dlm_put(dlm);

    return status;
}


/* fetch next node-local (u8 nodenum + u56 cookie) into u64 */
static inline void dlm_get_next_cookie(u8 node_num, u64 *cookie)
{
    u64 tmpnode = node_num;

    /* shift single byte of node num into top 8 bits */
    tmpnode <<= 56;

    spin_lock(&dlm_cookie_lock);
    *cookie = (dlm_next_cookie | tmpnode);
    if (++dlm_next_cookie & 0xff00000000000000ull) {
        mlog(0, "This node's cookie will now wrap!\n");
        dlm_next_cookie = 1;
    }
    spin_unlock(&dlm_cookie_lock);
}

enum dlm_status dlmlock(struct dlm_ctxt *dlm, int mode,
            struct dlm_lockstatus *lksb, int flags,
            const char *name, int namelen, dlm_astlockfunc_t *ast,
            void *data, dlm_bastlockfunc_t *bast)
{
    enum dlm_status status;
    struct dlm_lock_resource *res = NULL;
    struct dlm_lock *lock = NULL;
    int convert = 0, recovery = 0;

    /* yes this function is a mess.
     * TODO: clean this up.  lots of common code in the
     *       lock and convert paths, especially in the retry blocks */
    if (!lksb) {
        dlm_error(DLM_BADARGS);
        return DLM_BADARGS;
    }

    status = DLM_BADPARAM;
    if (mode != LKM_EXMODE && mode != LKM_PRMODE && mode != LKM_NLMODE) {
        dlm_error(status);
        goto error;
    }

    if (flags & ~LKM_VALID_FLAGS) {
        dlm_error(status);
        goto error;
    }

    convert = (flags & LKM_CONVERT);
    recovery = (flags & LKM_RECOVERY);

    if (recovery &&
        (!dlm_is_recovery_lock(name, namelen) || convert) ) {
        dlm_error(status);
        goto error;
    }
    if (convert && (flags & LKM_LOCAL)) {
        mlog(ML_ERROR, "strange LOCAL convert request!\n");
        goto error;
    }

    if (convert) {
        /* CONVERT request */

        /* if converting, must pass in a valid dlm_lock */
        lock = lksb->lockid;
        if (!lock) {
            mlog(ML_ERROR, "NULL lock pointer in convert "
                 "request\n");
            goto error;
        }

        res = lock->lockres;
        if (!res) {
            mlog(ML_ERROR, "NULL lockres pointer in convert "
                 "request\n");
            goto error;
        }
        dlm_lockres_get(res);

        /* XXX: for ocfs2 purposes, the ast/bast/astdata/lksb are
         * static after the original lock call.  convert requests will
         * ensure that everything is the same, or return DLM_BADARGS.
         * this means that DLM_DENIED_NOASTS will never be returned.
         */
        if (lock->lksb != lksb || lock->ast != ast ||
            lock->bast != bast || lock->astdata != data) {
            status = DLM_BADARGS;
            mlog(ML_ERROR, "new args:  lksb=%p, ast=%p, bast=%p, "
                 "astdata=%p\n", lksb, ast, bast, data);
            mlog(ML_ERROR, "orig args: lksb=%p, ast=%p, bast=%p, "
                 "astdata=%p\n", lock->lksb, lock->ast,
                 lock->bast, lock->astdata);
            goto error;
        }
retry_convert:
        dlm_wait_for_recovery(dlm);

        if (res->owner == dlm->node_num)
            status = dlmconvert_master(dlm, res, lock, flags, mode);
        else
            status = dlmconvert_remote(dlm, res, lock, flags, mode);
        if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
            status == DLM_FORWARD) {
            /* for now, see how this works without sleeping
             * and just retry right away.  I suspect the reco
             * or migration will complete fast enough that
             * no waiting will be necessary */
            mlog(0, "retrying convert with migration/recovery/"
                 "in-progress\n");
            msleep(100);
            goto retry_convert;
        }
    } else {
        u64 tmpcookie;

        /* LOCK request */
        status = DLM_BADARGS;
        if (!name) {
            dlm_error(status);
            goto error;
        }

        status = DLM_IVBUFLEN;
        if (namelen > DLM_LOCKID_NAME_MAX || namelen < 1) {
            dlm_error(status);
            goto error;
        }

        dlm_get_next_cookie(dlm->node_num, &tmpcookie);
        lock = dlm_new_lock(mode, dlm->node_num, tmpcookie, lksb);
        if (!lock) {
            dlm_error(status);
            goto error;
        }

        if (!recovery)
            dlm_wait_for_recovery(dlm);

        /* find or create the lock resource */
        res = dlm_get_lock_resource(dlm, name, namelen, flags);
        if (!res) {
            status = DLM_IVLOCKID;
            dlm_error(status);
            goto error;
        }

        mlog(0, "type=%d, flags = 0x%x\n", mode, flags);
        mlog(0, "creating lock: lock=%p res=%p\n", lock, res);

        dlm_lock_attach_lockres(lock, res);
        lock->ast = ast;
        lock->bast = bast;
        lock->astdata = data;

retry_lock:
        if (flags & LKM_VALBLK) {
            mlog(0, "LKM_VALBLK passed by caller\n");

            /* LVB requests for non PR, PW or EX locks are
             * ignored. */
            if (mode < LKM_PRMODE)
                flags &= ~LKM_VALBLK;
            else {
                flags |= LKM_GET_LVB;
                lock->lksb->flags |= DLM_LKSB_GET_LVB;
            }
        }

        if (res->owner == dlm->node_num)
            status = dlmlock_master(dlm, res, lock, flags);
        else
            status = dlmlock_remote(dlm, res, lock, flags);

        if (status == DLM_RECOVERING || status == DLM_MIGRATING ||
            status == DLM_FORWARD) {
            msleep(100);
            if (recovery) {
                if (status != DLM_RECOVERING)
                    goto retry_lock;
                /* wait to see the node go down, then
                 * drop down and allow the lockres to
                 * get cleaned up.  need to remaster. */
                dlm_wait_for_node_death(dlm, res->owner,
                        DLM_NODE_DEATH_WAIT_MAX);
            } else {
                dlm_wait_for_recovery(dlm);
                goto retry_lock;
            }
        }

        /* Inflight taken in dlm_get_lock_resource() is dropped here */
        spin_lock(&res->spinlock);
        dlm_lockres_drop_inflight_ref(dlm, res);
        spin_unlock(&res->spinlock);

        dlm_lockres_calc_usage(dlm, res);
        dlm_kick_thread(dlm, res);

        if (status != DLM_NORMAL) {
            lock->lksb->flags &= ~DLM_LKSB_GET_LVB;
            if (status != DLM_NOTQUEUED)
                dlm_error(status);
            goto error;
        }
    }

error:
    if (status != DLM_NORMAL) {
        if (lock && !convert)
            dlm_lock_put(lock);
        // this is kind of unnecessary
        lksb->status = status;
    }

    /* put lockres ref from the convert path
     * or from dlm_get_lock_resource */
    if (res)
        dlm_lockres_put(res);

    return status;
}
EXPORT_SYMBOL_GPL(dlmlock);