/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * 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 version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003 Hewlett-Packard Development Company LP.
 * Developed under the sponsorship of the US Government under
 * Subcontract No. B514193
 *
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2010, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

/**
 * This file implements POSIX lock type for Lustre.
 * Its policy properties are start and end of extent and PID.
 *
 * These locks are only done through MDS due to POSIX semantics requiring
 * e.g. that locks could be only partially released and as such split into
 * two parts, and also that two adjacent locks from the same process may be
 * merged into a single wider lock.
 *
 * Lock modes are mapped like this:
 * PR and PW for READ and WRITE locks
 * NL to request a releasing of a portion of the lock
 *
 * These flock locks never timeout.
 */

#define DEBUG_SUBSYSTEM S_LDLM

#include "../include/lustre_dlm.h"
#include "../include/obd_support.h"
#include "../include/obd_class.h"
#include "../include/lustre_lib.h"
#include <linux/list.h>
#include "ldlm_internal.h"

int ldlm_flock_blocking_ast(struct ldlm_lock *lock, struct ldlm_lock_desc *desc,
                            void *data, int flag);

/**
 * list_for_remaining_safe - iterate over the remaining entries in a list
 *            and safeguard against removal of a list entry.
 * \param pos   the &struct list_head to use as a loop counter. pos MUST
 *            have been initialized prior to using it in this macro.
 * \param n     another &struct list_head to use as temporary storage
 * \param head  the head for your list.
 */
#define list_for_remaining_safe(pos, n, head) \
        for (n = pos->next; pos != (head); pos = n, n = pos->next)

static inline int
ldlm_same_flock_owner(struct ldlm_lock *lock, struct ldlm_lock *new)
{
        return((new->l_policy_data.l_flock.owner ==
                lock->l_policy_data.l_flock.owner) &&
               (new->l_export == lock->l_export));
}

static inline int
ldlm_flocks_overlap(struct ldlm_lock *lock, struct ldlm_lock *new)
{
        return((new->l_policy_data.l_flock.start <=
                lock->l_policy_data.l_flock.end) &&
               (new->l_policy_data.l_flock.end >=
                lock->l_policy_data.l_flock.start));
}

static inline void ldlm_flock_blocking_link(struct ldlm_lock *req,
                                            struct ldlm_lock *lock)
{
        /* For server only */
        if (req->l_export == NULL)
                return;

        LASSERT(hlist_unhashed(&req->l_exp_flock_hash));

        req->l_policy_data.l_flock.blocking_owner =
                lock->l_policy_data.l_flock.owner;
        req->l_policy_data.l_flock.blocking_export =
                lock->l_export;
        req->l_policy_data.l_flock.blocking_refs = 0;

        cfs_hash_add(req->l_export->exp_flock_hash,
                     &req->l_policy_data.l_flock.owner,
                     &req->l_exp_flock_hash);
}

static inline void ldlm_flock_blocking_unlink(struct ldlm_lock *req)
{
        /* For server only */
        if (req->l_export == NULL)
                return;

        check_res_locked(req->l_resource);
        if (req->l_export->exp_flock_hash != NULL &&
            !hlist_unhashed(&req->l_exp_flock_hash))
                cfs_hash_del(req->l_export->exp_flock_hash,
                             &req->l_policy_data.l_flock.owner,
                             &req->l_exp_flock_hash);
}

static inline void
ldlm_flock_destroy(struct ldlm_lock *lock, ldlm_mode_t mode, __u64 flags)
{
        LDLM_DEBUG(lock, "ldlm_flock_destroy(mode: %d, flags: 0x%llx)",
                   mode, flags);

        /* Safe to not lock here, since it should be empty anyway */
        LASSERT(hlist_unhashed(&lock->l_exp_flock_hash));

        list_del_init(&lock->l_res_link);
        if (flags == LDLM_FL_WAIT_NOREPROC &&
            !(lock->l_flags & LDLM_FL_FAILED)) {
                /* client side - set a flag to prevent sending a CANCEL */
                lock->l_flags |= LDLM_FL_LOCAL_ONLY | LDLM_FL_CBPENDING;

                /* when reaching here, it is under lock_res_and_lock(). Thus,
                   need call the nolock version of ldlm_lock_decref_internal*/
                ldlm_lock_decref_internal_nolock(lock, mode);
        }

        ldlm_lock_destroy_nolock(lock);
}

/**
 * POSIX locks deadlock detection code.
 *
 * Given a new lock \a req and an existing lock \a bl_lock it conflicts
 * with, we need to iterate through all blocked POSIX locks for this
 * export and see if there is a deadlock condition arising. (i.e. when
 * one client holds a lock on something and want a lock on something
 * else and at the same time another client has the opposite situation).
 */
static int
ldlm_flock_deadlock(struct ldlm_lock *req, struct ldlm_lock *bl_lock)
{
        struct obd_export *req_exp = req->l_export;
        struct obd_export *bl_exp = bl_lock->l_export;
        __u64 req_owner = req->l_policy_data.l_flock.owner;
        __u64 bl_owner = bl_lock->l_policy_data.l_flock.owner;

        /* For server only */
        if (req_exp == NULL)
                return 0;

        class_export_get(bl_exp);
        while (1) {
                struct obd_export *bl_exp_new;
                struct ldlm_lock *lock = NULL;
                struct ldlm_flock *flock;

                if (bl_exp->exp_flock_hash != NULL)
                        lock = cfs_hash_lookup(bl_exp->exp_flock_hash,
                                               &bl_owner);
                if (lock == NULL)
                        break;

                LASSERT(req != lock);
                flock = &lock->l_policy_data.l_flock;
                LASSERT(flock->owner == bl_owner);
                bl_owner = flock->blocking_owner;
                bl_exp_new = class_export_get(flock->blocking_export);
                class_export_put(bl_exp);

                cfs_hash_put(bl_exp->exp_flock_hash, &lock->l_exp_flock_hash);
                bl_exp = bl_exp_new;

                if (bl_owner == req_owner && bl_exp == req_exp) {
                        class_export_put(bl_exp);
                        return 1;
                }
        }
        class_export_put(bl_exp);

        return 0;
}

static void ldlm_flock_cancel_on_deadlock(struct ldlm_lock *lock,
                                          struct list_head *work_list)
{
        CDEBUG(D_INFO, "reprocess deadlock req=%p\n", lock);

        if ((exp_connect_flags(lock->l_export) &
                                OBD_CONNECT_FLOCK_DEAD) == 0) {
                CERROR(
                      "deadlock found, but client doesn't support flock canceliation\n");
        } else {
                LASSERT(lock->l_completion_ast);
                LASSERT((lock->l_flags & LDLM_FL_AST_SENT) == 0);
                lock->l_flags |= LDLM_FL_AST_SENT | LDLM_FL_CANCEL_ON_BLOCK |
                        LDLM_FL_FLOCK_DEADLOCK;
                ldlm_flock_blocking_unlink(lock);
                ldlm_resource_unlink_lock(lock);
                ldlm_add_ast_work_item(lock, NULL, work_list);
        }
}

/**
 * Process a granting attempt for flock lock.
 * Must be called under ns lock held.
 *
 * This function looks for any conflicts for \a lock in the granted or
 * waiting queues. The lock is granted if no conflicts are found in
 * either queue.
 *
 * It is also responsible for splitting a lock if a portion of the lock
 * is released.
 *
 * If \a first_enq is 0 (ie, called from ldlm_reprocess_queue):
 *   - blocking ASTs have already been sent
 *
 * If \a first_enq is 1 (ie, called from ldlm_lock_enqueue):
 *   - blocking ASTs have not been sent yet, so list of conflicting locks
 *     would be collected and ASTs sent.
 */
int
ldlm_process_flock_lock(struct ldlm_lock *req, __u64 *flags, int first_enq,
                        ldlm_error_t *err, struct list_head *work_list)
{
        struct ldlm_resource *res = req->l_resource;
        struct ldlm_namespace *ns = ldlm_res_to_ns(res);
        struct list_head *tmp;
        struct list_head *ownlocks = NULL;
        struct ldlm_lock *lock = NULL;
        struct ldlm_lock *new = req;
        struct ldlm_lock *new2 = NULL;
        ldlm_mode_t mode = req->l_req_mode;
        int local = ns_is_client(ns);
        int added = (mode == LCK_NL);
        int overlaps = 0;
        int splitted = 0;
        const struct ldlm_callback_suite null_cbs = { NULL };

        CDEBUG(D_DLMTRACE,
               "flags %#llx owner %llu pid %u mode %u start %llu end %llu\n",
               *flags, new->l_policy_data.l_flock.owner,
               new->l_policy_data.l_flock.pid, mode,
               req->l_policy_data.l_flock.start,
               req->l_policy_data.l_flock.end);

        *err = ELDLM_OK;

        if (local) {
                /* No blocking ASTs are sent to the clients for
                 * Posix file & record locks */
                req->l_blocking_ast = NULL;
        } else {
                /* Called on the server for lock cancels. */
                req->l_blocking_ast = ldlm_flock_blocking_ast;
        }

reprocess:
        if ((*flags == LDLM_FL_WAIT_NOREPROC) || (mode == LCK_NL)) {
                /* This loop determines where this processes locks start
                 * in the resource lr_granted list. */
                list_for_each(tmp, &res->lr_granted) {
                        lock = list_entry(tmp, struct ldlm_lock,
                                              l_res_link);
                        if (ldlm_same_flock_owner(lock, req)) {
                                ownlocks = tmp;
                                break;
                        }
                }
        } else {
                int reprocess_failed = 0;

                lockmode_verify(mode);

                /* This loop determines if there are existing locks
                 * that conflict with the new lock request. */
                list_for_each(tmp, &res->lr_granted) {
                        lock = list_entry(tmp, struct ldlm_lock,
                                              l_res_link);

                        if (ldlm_same_flock_owner(lock, req)) {
                                if (!ownlocks)
                                        ownlocks = tmp;
                                continue;
                        }

                        /* locks are compatible, overlap doesn't matter */
                        if (lockmode_compat(lock->l_granted_mode, mode))
                                continue;

                        if (!ldlm_flocks_overlap(lock, req))
                                continue;

                        if (!first_enq) {
                                reprocess_failed = 1;
                                if (ldlm_flock_deadlock(req, lock)) {
                                        ldlm_flock_cancel_on_deadlock(req,
                                                        work_list);
                                        return LDLM_ITER_CONTINUE;
                                }
                                continue;
                        }

                        if (*flags & LDLM_FL_BLOCK_NOWAIT) {
                                ldlm_flock_destroy(req, mode, *flags);
                                *err = -EAGAIN;
                                return LDLM_ITER_STOP;
                        }

                        if (*flags & LDLM_FL_TEST_LOCK) {
                                ldlm_flock_destroy(req, mode, *flags);
                                req->l_req_mode = lock->l_granted_mode;
                                req->l_policy_data.l_flock.pid =
                                        lock->l_policy_data.l_flock.pid;
                                req->l_policy_data.l_flock.start =
                                        lock->l_policy_data.l_flock.start;
                                req->l_policy_data.l_flock.end =
                                        lock->l_policy_data.l_flock.end;
                                *flags |= LDLM_FL_LOCK_CHANGED;
                                return LDLM_ITER_STOP;
                        }

                        /* add lock to blocking list before deadlock
                         * check to prevent race */
                        ldlm_flock_blocking_link(req, lock);

                        if (ldlm_flock_deadlock(req, lock)) {
                                ldlm_flock_blocking_unlink(req);
                                ldlm_flock_destroy(req, mode, *flags);
                                *err = -EDEADLK;
                                return LDLM_ITER_STOP;
                        }

                        ldlm_resource_add_lock(res, &res->lr_waiting, req);
                        *flags |= LDLM_FL_BLOCK_GRANTED;
                        return LDLM_ITER_STOP;
                }
                if (reprocess_failed)
                        return LDLM_ITER_CONTINUE;
        }

        if (*flags & LDLM_FL_TEST_LOCK) {
                ldlm_flock_destroy(req, mode, *flags);
                req->l_req_mode = LCK_NL;
                *flags |= LDLM_FL_LOCK_CHANGED;
                return LDLM_ITER_STOP;
        }

        /* In case we had slept on this lock request take it off of the
         * deadlock detection hash list. */
        ldlm_flock_blocking_unlink(req);

        /* Scan the locks owned by this process that overlap this request.
         * We may have to merge or split existing locks. */

        if (!ownlocks)
                ownlocks = &res->lr_granted;

        list_for_remaining_safe(ownlocks, tmp, &res->lr_granted) {
                lock = list_entry(ownlocks, struct ldlm_lock, l_res_link);

                if (!ldlm_same_flock_owner(lock, new))
                        break;

                if (lock->l_granted_mode == mode) {
                        /* If the modes are the same then we need to process
                         * locks that overlap OR adjoin the new lock. The extra
                         * logic condition is necessary to deal with arithmetic
                         * overflow and underflow. */
                        if ((new->l_policy_data.l_flock.start >
                             (lock->l_policy_data.l_flock.end + 1))
                            && (lock->l_policy_data.l_flock.end !=
                                OBD_OBJECT_EOF))
                                continue;

                        if ((new->l_policy_data.l_flock.end <
                             (lock->l_policy_data.l_flock.start - 1))
                            && (lock->l_policy_data.l_flock.start != 0))
                                break;

                        if (new->l_policy_data.l_flock.start <
                            lock->l_policy_data.l_flock.start) {
                                lock->l_policy_data.l_flock.start =
                                        new->l_policy_data.l_flock.start;
                        } else {
                                new->l_policy_data.l_flock.start =
                                        lock->l_policy_data.l_flock.start;
                        }

                        if (new->l_policy_data.l_flock.end >
                            lock->l_policy_data.l_flock.end) {
                                lock->l_policy_data.l_flock.end =
                                        new->l_policy_data.l_flock.end;
                        } else {
                                new->l_policy_data.l_flock.end =
                                        lock->l_policy_data.l_flock.end;
                        }

                        if (added) {
                                ldlm_flock_destroy(lock, mode, *flags);
                        } else {
                                new = lock;
                                added = 1;
                        }
                        continue;
                }

                if (new->l_policy_data.l_flock.start >
                    lock->l_policy_data.l_flock.end)
                        continue;

                if (new->l_policy_data.l_flock.end <
                    lock->l_policy_data.l_flock.start)
                        break;

                ++overlaps;

                if (new->l_policy_data.l_flock.start <=
                    lock->l_policy_data.l_flock.start) {
                        if (new->l_policy_data.l_flock.end <
                            lock->l_policy_data.l_flock.end) {
                                lock->l_policy_data.l_flock.start =
                                        new->l_policy_data.l_flock.end + 1;
                                break;
                        }
                        ldlm_flock_destroy(lock, lock->l_req_mode, *flags);
                        continue;
                }
                if (new->l_policy_data.l_flock.end >=
                    lock->l_policy_data.l_flock.end) {
                        lock->l_policy_data.l_flock.end =
                                new->l_policy_data.l_flock.start - 1;
                        continue;
                }

                /* split the existing lock into two locks */

                /* if this is an F_UNLCK operation then we could avoid
                 * allocating a new lock and use the req lock passed in
                 * with the request but this would complicate the reply
                 * processing since updates to req get reflected in the
                 * reply. The client side replays the lock request so
                 * it must see the original lock data in the reply. */

                /* XXX - if ldlm_lock_new() can sleep we should
                 * release the lr_lock, allocate the new lock,
                 * and restart processing this lock. */
                if (!new2) {
                        unlock_res_and_lock(req);
                        new2 = ldlm_lock_create(ns, &res->lr_name, LDLM_FLOCK,
                                                lock->l_granted_mode, &null_cbs,
                                                NULL, 0, LVB_T_NONE);
                        lock_res_and_lock(req);
                        if (!new2) {
                                ldlm_flock_destroy(req, lock->l_granted_mode,
                                                   *flags);
                                *err = -ENOLCK;
                                return LDLM_ITER_STOP;
                        }
                        goto reprocess;
                }

                splitted = 1;

                new2->l_granted_mode = lock->l_granted_mode;
                new2->l_policy_data.l_flock.pid =
                        new->l_policy_data.l_flock.pid;
                new2->l_policy_data.l_flock.owner =
                        new->l_policy_data.l_flock.owner;
                new2->l_policy_data.l_flock.start =
                        lock->l_policy_data.l_flock.start;
                new2->l_policy_data.l_flock.end =
                        new->l_policy_data.l_flock.start - 1;
                lock->l_policy_data.l_flock.start =
                        new->l_policy_data.l_flock.end + 1;
                new2->l_conn_export = lock->l_conn_export;
                if (lock->l_export != NULL) {
                        new2->l_export = class_export_lock_get(lock->l_export,
                                                               new2);
                        if (new2->l_export->exp_lock_hash &&
                            hlist_unhashed(&new2->l_exp_hash))
                                cfs_hash_add(new2->l_export->exp_lock_hash,
                                             &new2->l_remote_handle,
                                             &new2->l_exp_hash);
                }
                if (*flags == LDLM_FL_WAIT_NOREPROC)
                        ldlm_lock_addref_internal_nolock(new2,
                                                         lock->l_granted_mode);

                /* insert new2 at lock */
                ldlm_resource_add_lock(res, ownlocks, new2);
                LDLM_LOCK_RELEASE(new2);
                break;
        }

        /* if new2 is created but never used, destroy it*/
        if (splitted == 0 && new2 != NULL)
                ldlm_lock_destroy_nolock(new2);

        /* At this point we're granting the lock request. */
        req->l_granted_mode = req->l_req_mode;

        /* Add req to the granted queue before calling ldlm_reprocess_all(). */
        if (!added) {
                list_del_init(&req->l_res_link);
                /* insert new lock before ownlocks in list. */
                ldlm_resource_add_lock(res, ownlocks, req);
        }

        if (*flags != LDLM_FL_WAIT_NOREPROC) {
                /* The only one possible case for client-side calls flock
                 * policy function is ldlm_flock_completion_ast inside which
                 * carries LDLM_FL_WAIT_NOREPROC flag. */
                CERROR("Illegal parameter for client-side-only module.\n");
                LBUG();
        }

        /* In case we're reprocessing the requested lock we can't destroy
         * it until after calling ldlm_add_ast_work_item() above so that laawi()
         * can bump the reference count on \a req. Otherwise \a req
         * could be freed before the completion AST can be sent.  */
        if (added)
                ldlm_flock_destroy(req, mode, *flags);

        ldlm_resource_dump(D_INFO, res);
        return LDLM_ITER_CONTINUE;
}

struct ldlm_flock_wait_data {
        struct ldlm_lock *fwd_lock;
        int            fwd_generation;
};

static void
ldlm_flock_interrupted_wait(void *data)
{
        struct ldlm_lock *lock;

        lock = ((struct ldlm_flock_wait_data *)data)->fwd_lock;

        /* take lock off the deadlock detection hash list. */
        lock_res_and_lock(lock);
        ldlm_flock_blocking_unlink(lock);

        /* client side - set flag to prevent lock from being put on LRU list */
        lock->l_flags |= LDLM_FL_CBPENDING;
        unlock_res_and_lock(lock);
}

/**
 * Flock completion callback function.
 *
 * \param lock [in,out]: A lock to be handled
 * \param flags    [in]: flags
 * \param *data    [in]: ldlm_work_cp_ast_lock() will use ldlm_cb_set_arg
 *
 * \retval 0    : success
 * \retval <0   : failure
 */
int
ldlm_flock_completion_ast(struct ldlm_lock *lock, __u64 flags, void *data)
{
        struct file_lock                *getlk = lock->l_ast_data;
        struct obd_device             *obd;
        struct obd_import             *imp = NULL;
        struct ldlm_flock_wait_data     fwd;
        struct l_wait_info            lwi;
        ldlm_error_t                err;
        int                          rc = 0;

        CDEBUG(D_DLMTRACE, "flags: 0x%llx data: %p getlk: %p\n",
               flags, data, getlk);

        /* Import invalidation. We need to actually release the lock
         * references being held, so that it can go away. No point in
         * holding the lock even if app still believes it has it, since
         * server already dropped it anyway. Only for granted locks too. */
        if ((lock->l_flags & (LDLM_FL_FAILED|LDLM_FL_LOCAL_ONLY)) ==
            (LDLM_FL_FAILED|LDLM_FL_LOCAL_ONLY)) {
                if (lock->l_req_mode == lock->l_granted_mode &&
                    lock->l_granted_mode != LCK_NL &&
                    NULL == data)
                        ldlm_lock_decref_internal(lock, lock->l_req_mode);

                /* Need to wake up the waiter if we were evicted */
                wake_up(&lock->l_waitq);
                return 0;
        }

        LASSERT(flags != LDLM_FL_WAIT_NOREPROC);

        if (!(flags & (LDLM_FL_BLOCK_WAIT | LDLM_FL_BLOCK_GRANTED |
                       LDLM_FL_BLOCK_CONV))) {
                if (NULL == data)
                        /* mds granted the lock in the reply */
                        goto granted;
                /* CP AST RPC: lock get granted, wake it up */
                wake_up(&lock->l_waitq);
                return 0;
        }

        LDLM_DEBUG(lock, "client-side enqueue returned a blocked lock, sleeping");
        fwd.fwd_lock = lock;
        obd = class_exp2obd(lock->l_conn_export);

        /* if this is a local lock, there is no import */
        if (NULL != obd)
                imp = obd->u.cli.cl_import;

        if (NULL != imp) {
                spin_lock(&imp->imp_lock);
                fwd.fwd_generation = imp->imp_generation;
                spin_unlock(&imp->imp_lock);
        }

        lwi = LWI_TIMEOUT_INTR(0, NULL, ldlm_flock_interrupted_wait, &fwd);

        /* Go to sleep until the lock is granted. */
        rc = l_wait_event(lock->l_waitq, is_granted_or_cancelled(lock), &lwi);

        if (rc) {
                LDLM_DEBUG(lock, "client-side enqueue waking up: failed (%d)",
                           rc);
                return rc;
        }

granted:
        OBD_FAIL_TIMEOUT(OBD_FAIL_LDLM_CP_CB_WAIT, 10);

        if (lock->l_flags & LDLM_FL_DESTROYED) {
                LDLM_DEBUG(lock, "client-side enqueue waking up: destroyed");
                return 0;
        }

        if (lock->l_flags & LDLM_FL_FAILED) {
                LDLM_DEBUG(lock, "client-side enqueue waking up: failed");
                return -EIO;
        }

        if (rc) {
                LDLM_DEBUG(lock, "client-side enqueue waking up: failed (%d)",
                           rc);
                return rc;
        }

        LDLM_DEBUG(lock, "client-side enqueue granted");

        lock_res_and_lock(lock);

        /* take lock off the deadlock detection hash list. */
        ldlm_flock_blocking_unlink(lock);

        /* ldlm_lock_enqueue() has already placed lock on the granted list. */
        list_del_init(&lock->l_res_link);

        if (lock->l_flags & LDLM_FL_FLOCK_DEADLOCK) {
                LDLM_DEBUG(lock, "client-side enqueue deadlock received");
                rc = -EDEADLK;
        } else if (flags & LDLM_FL_TEST_LOCK) {
                /* fcntl(F_GETLK) request */
                /* The old mode was saved in getlk->fl_type so that if the mode
                 * in the lock changes we can decref the appropriate refcount.*/
                ldlm_flock_destroy(lock, getlk->fl_type, LDLM_FL_WAIT_NOREPROC);
                switch (lock->l_granted_mode) {
                case LCK_PR:
                        getlk->fl_type = F_RDLCK;
                        break;
                case LCK_PW:
                        getlk->fl_type = F_WRLCK;
                        break;
                default:
                        getlk->fl_type = F_UNLCK;
                }
                getlk->fl_pid = (pid_t)lock->l_policy_data.l_flock.pid;
                getlk->fl_start = (loff_t)lock->l_policy_data.l_flock.start;
                getlk->fl_end = (loff_t)lock->l_policy_data.l_flock.end;
        } else {
                __u64 noreproc = LDLM_FL_WAIT_NOREPROC;

                /* We need to reprocess the lock to do merges or splits
                 * with existing locks owned by this process. */
                ldlm_process_flock_lock(lock, &noreproc, 1, &err, NULL);
        }
        unlock_res_and_lock(lock);
        return rc;
}
EXPORT_SYMBOL(ldlm_flock_completion_ast);

int ldlm_flock_blocking_ast(struct ldlm_lock *lock, struct ldlm_lock_desc *desc,
                            void *data, int flag)
{
        LASSERT(lock);
        LASSERT(flag == LDLM_CB_CANCELING);

        /* take lock off the deadlock detection hash list. */
        lock_res_and_lock(lock);
        ldlm_flock_blocking_unlink(lock);
        unlock_res_and_lock(lock);
        return 0;
}

void ldlm_flock_policy_wire18_to_local(const ldlm_wire_policy_data_t *wpolicy,
                                       ldlm_policy_data_t *lpolicy)
{
        memset(lpolicy, 0, sizeof(*lpolicy));
        lpolicy->l_flock.start = wpolicy->l_flock.lfw_start;
        lpolicy->l_flock.end = wpolicy->l_flock.lfw_end;
        lpolicy->l_flock.pid = wpolicy->l_flock.lfw_pid;
        /* Compat code, old clients had no idea about owner field and
         * relied solely on pid for ownership. Introduced in LU-104, 2.1,
         * April 2011 */
        lpolicy->l_flock.owner = wpolicy->l_flock.lfw_pid;
}


void ldlm_flock_policy_wire21_to_local(const ldlm_wire_policy_data_t *wpolicy,
                                       ldlm_policy_data_t *lpolicy)
{
        memset(lpolicy, 0, sizeof(*lpolicy));
        lpolicy->l_flock.start = wpolicy->l_flock.lfw_start;
        lpolicy->l_flock.end = wpolicy->l_flock.lfw_end;
        lpolicy->l_flock.pid = wpolicy->l_flock.lfw_pid;
        lpolicy->l_flock.owner = wpolicy->l_flock.lfw_owner;
}

void ldlm_flock_policy_local_to_wire(const ldlm_policy_data_t *lpolicy,
                                     ldlm_wire_policy_data_t *wpolicy)
{
        memset(wpolicy, 0, sizeof(*wpolicy));
        wpolicy->l_flock.lfw_start = lpolicy->l_flock.start;
        wpolicy->l_flock.lfw_end = lpolicy->l_flock.end;
        wpolicy->l_flock.lfw_pid = lpolicy->l_flock.pid;
        wpolicy->l_flock.lfw_owner = lpolicy->l_flock.owner;
}

/*
 * Export handle<->flock hash operations.
 */
static unsigned
ldlm_export_flock_hash(struct cfs_hash *hs, const void *key, unsigned mask)
{
        return cfs_hash_u64_hash(*(__u64 *)key, mask);
}

static void *
ldlm_export_flock_key(struct hlist_node *hnode)
{
        struct ldlm_lock *lock;

        lock = hlist_entry(hnode, struct ldlm_lock, l_exp_flock_hash);
        return &lock->l_policy_data.l_flock.owner;
}

static int
ldlm_export_flock_keycmp(const void *key, struct hlist_node *hnode)
{
        return !memcmp(ldlm_export_flock_key(hnode), key, sizeof(__u64));
}

static void *
ldlm_export_flock_object(struct hlist_node *hnode)
{
        return hlist_entry(hnode, struct ldlm_lock, l_exp_flock_hash);
}

static void
ldlm_export_flock_get(struct cfs_hash *hs, struct hlist_node *hnode)
{
        struct ldlm_lock *lock;
        struct ldlm_flock *flock;

        lock = hlist_entry(hnode, struct ldlm_lock, l_exp_flock_hash);
        LDLM_LOCK_GET(lock);

        flock = &lock->l_policy_data.l_flock;
        LASSERT(flock->blocking_export != NULL);
        class_export_get(flock->blocking_export);
        flock->blocking_refs++;
}

static void
ldlm_export_flock_put(struct cfs_hash *hs, struct hlist_node *hnode)
{
        struct ldlm_lock *lock;
        struct ldlm_flock *flock;

        lock = hlist_entry(hnode, struct ldlm_lock, l_exp_flock_hash);
        LDLM_LOCK_RELEASE(lock);

        flock = &lock->l_policy_data.l_flock;
        LASSERT(flock->blocking_export != NULL);
        class_export_put(flock->blocking_export);
        if (--flock->blocking_refs == 0) {
                flock->blocking_owner = 0;
                flock->blocking_export = NULL;
        }
}

static cfs_hash_ops_t ldlm_export_flock_ops = {
        .hs_hash        = ldlm_export_flock_hash,
        .hs_key  = ldlm_export_flock_key,
        .hs_keycmp      = ldlm_export_flock_keycmp,
        .hs_object      = ldlm_export_flock_object,
        .hs_get  = ldlm_export_flock_get,
        .hs_put  = ldlm_export_flock_put,
        .hs_put_locked  = ldlm_export_flock_put,
};

int ldlm_init_flock_export(struct obd_export *exp)
{
        if (strcmp(exp->exp_obd->obd_type->typ_name, LUSTRE_MDT_NAME) != 0)
                return 0;

        exp->exp_flock_hash =
                cfs_hash_create(obd_uuid2str(&exp->exp_client_uuid),
                                HASH_EXP_LOCK_CUR_BITS,
                                HASH_EXP_LOCK_MAX_BITS,
                                HASH_EXP_LOCK_BKT_BITS, 0,
                                CFS_HASH_MIN_THETA, CFS_HASH_MAX_THETA,
                                &ldlm_export_flock_ops,
                                CFS_HASH_DEFAULT | CFS_HASH_NBLK_CHANGE);
        if (!exp->exp_flock_hash)
                return -ENOMEM;

        return 0;
}
EXPORT_SYMBOL(ldlm_init_flock_export);

void ldlm_destroy_flock_export(struct obd_export *exp)
{
        if (exp->exp_flock_hash) {
                cfs_hash_putref(exp->exp_flock_hash);
                exp->exp_flock_hash = NULL;
        }
}
EXPORT_SYMBOL(ldlm_destroy_flock_export);