/* * 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, 2010, Oracle and/or its affiliates. All rights reserved. * Use is subject to license terms. * * Copyright (c) 2011, Intel Corporation. */ /* * This file is part of Lustre, http://www.lustre.org/ * Lustre is a trademark of Sun Microsystems, Inc. * * lustre/ldlm/ldlm_plain.c * * Author: Peter Braam * Author: Phil Schwan */ /** * This file contains implementation of PLAIN lock type. * * PLAIN locks are the simplest form of LDLM locking, and are used when * there only needs to be a single lock on a resource. This avoids some * of the complexity of EXTENT and IBITS lock types, but doesn't allow * different "parts" of a resource to be locked concurrently. Example * use cases for PLAIN locks include locking of MGS configuration logs * and (as of Lustre 2.4) quota records. */ #define DEBUG_SUBSYSTEM S_LDLM #ifdef __KERNEL__ #include #include #include #else #include #endif #include "ldlm_internal.h" #ifdef HAVE_SERVER_SUPPORT /** * Determine if the lock is compatible with all locks on the queue. * * If \a work_list is provided, conflicting locks are linked there. * If \a work_list is not provided, we exit this function on first conflict. * * \retval 0 if there are conflicting locks in the \a queue * \retval 1 if the lock is compatible to all locks in \a queue */ static inline int ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req, cfs_list_t *work_list) { cfs_list_t *tmp; struct ldlm_lock *lock; ldlm_mode_t req_mode = req->l_req_mode; int compat = 1; ENTRY; lockmode_verify(req_mode); cfs_list_for_each(tmp, queue) { lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link); /* We stop walking the queue if we hit ourselves so we don't * take conflicting locks enqueued after us into account, * or we'd wait forever. */ if (req == lock) RETURN(compat); /* Advance loop cursor to last lock of mode group. */ tmp = &cfs_list_entry(lock->l_sl_mode.prev, struct ldlm_lock, l_sl_mode)->l_res_link; if (lockmode_compat(lock->l_req_mode, req_mode)) continue; if (!work_list) RETURN(0); compat = 0; /* Add locks of the mode group to \a work_list as * blocking locks for \a req. */ if (lock->l_blocking_ast) ldlm_add_ast_work_item(lock, req, work_list); { cfs_list_t *head; head = &lock->l_sl_mode; cfs_list_for_each_entry(lock, head, l_sl_mode) if (lock->l_blocking_ast) ldlm_add_ast_work_item(lock, req, work_list); } } RETURN(compat); } /** * Process a granting attempt for plain lock. * Must be called with 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. * * 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_plain_lock(struct ldlm_lock *lock, __u64 *flags, int first_enq, ldlm_error_t *err, cfs_list_t *work_list) { struct ldlm_resource *res = lock->l_resource; CFS_LIST_HEAD(rpc_list); int rc; ENTRY; check_res_locked(res); LASSERT(cfs_list_empty(&res->lr_converting)); if (!first_enq) { LASSERT(work_list != NULL); rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL); if (!rc) RETURN(LDLM_ITER_STOP); rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL); if (!rc) RETURN(LDLM_ITER_STOP); ldlm_resource_unlink_lock(lock); ldlm_grant_lock(lock, work_list); RETURN(LDLM_ITER_CONTINUE); } restart: rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list); rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list); if (rc != 2) { /* If either of the compat_queue()s returned 0, then we * have ASTs to send and must go onto the waiting list. * * bug 2322: we used to unlink and re-add here, which was a * terrible folly -- if we goto restart, we could get * re-ordered! Causes deadlock, because ASTs aren't sent! */ if (cfs_list_empty(&lock->l_res_link)) ldlm_resource_add_lock(res, &res->lr_waiting, lock); unlock_res(res); rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list, LDLM_WORK_BL_AST); lock_res(res); if (rc == -ERESTART) GOTO(restart, -ERESTART); *flags |= LDLM_FL_BLOCK_GRANTED; } else { ldlm_resource_unlink_lock(lock); ldlm_grant_lock(lock, NULL); } RETURN(0); } #endif /* HAVE_SERVER_SUPPORT */ void ldlm_plain_policy_wire_to_local(const ldlm_wire_policy_data_t *wpolicy, ldlm_policy_data_t *lpolicy) { /* No policy for plain locks */ } void ldlm_plain_policy_local_to_wire(const ldlm_policy_data_t *lpolicy, ldlm_wire_policy_data_t *wpolicy) { /* No policy for plain locks */ }