Add the rt linux 4.1.3-rt3 as base
[kvmfornfv.git] / kernel / drivers / staging / lustre / lustre / ldlm / ldlm_flock.c
diff --git a/kernel/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c b/kernel/drivers/staging/lustre/lustre/ldlm/ldlm_flock.c
new file mode 100644 (file)
index 0000000..a4c252f
--- /dev/null
@@ -0,0 +1,859 @@
+/*
+ * 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);