4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 only,
8 * as published by the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License version 2 for more details (a copy is included
14 * in the LICENSE file that accompanied this code).
16 * You should have received a copy of the GNU General Public License
17 * version 2 along with this program; If not, see
18 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
20 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
21 * CA 95054 USA or visit www.sun.com if you need additional information or
27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
28 * Use is subject to license terms.
30 * Copyright (c) 2011, Intel Corporation.
33 * This file is part of Lustre, http://www.lustre.org/
34 * Lustre is a trademark of Sun Microsystems, Inc.
36 * lustre/ldlm/ldlm_plain.c
38 * Author: Peter Braam <braam@clusterfs.com>
39 * Author: Phil Schwan <phil@clusterfs.com>
43 * This file contains implementation of PLAIN lock type.
45 * PLAIN locks are the simplest form of LDLM locking, and are used when
46 * there only needs to be a single lock on a resource. This avoids some
47 * of the complexity of EXTENT and IBITS lock types, but doesn't allow
48 * different "parts" of a resource to be locked concurrently. Example
49 * use cases for PLAIN locks include locking of MGS configuration logs
50 * and (as of Lustre 2.4) quota records.
53 #define DEBUG_SUBSYSTEM S_LDLM
55 #include <lustre_dlm.h>
56 #include <obd_support.h>
57 #include <lustre_lib.h>
59 #include "ldlm_internal.h"
61 #ifdef HAVE_SERVER_SUPPORT
63 * Determine if the lock is compatible with all locks on the queue.
65 * If \a work_list is provided, conflicting locks are linked there.
66 * If \a work_list is not provided, we exit this function on first conflict.
68 * \retval 0 if there are conflicting locks in the \a queue
69 * \retval 1 if the lock is compatible to all locks in \a queue
72 ldlm_plain_compat_queue(struct list_head *queue, struct ldlm_lock *req,
73 struct list_head *work_list)
75 ldlm_mode_t req_mode = req->l_req_mode;
76 struct ldlm_lock *lock;
77 struct list_head *tmp;
81 lockmode_verify(req_mode);
83 list_for_each_entry(lock, queue, l_res_link) {
84 /* We stop walking the queue if we hit ourselves so we don't
85 * take conflicting locks enqueued after us into account,
86 * or we'd wait forever. */
90 /* Advance loop cursor to last lock of mode group. */
91 tmp = &list_entry(lock->l_sl_mode.prev, struct ldlm_lock,
92 l_sl_mode)->l_res_link;
94 if (lockmode_compat(lock->l_req_mode, req_mode))
102 /* Add locks of the mode group to \a work_list as
103 * blocking locks for \a req. */
104 if (lock->l_blocking_ast)
105 ldlm_add_ast_work_item(lock, req, work_list);
108 struct list_head *head;
110 head = &lock->l_sl_mode;
111 list_for_each_entry(lock, head, l_sl_mode)
112 if (lock->l_blocking_ast)
113 ldlm_add_ast_work_item(lock, req,
122 * Process a granting attempt for plain lock.
123 * Must be called with ns lock held.
125 * This function looks for any conflicts for \a lock in the granted or
126 * waiting queues. The lock is granted if no conflicts are found in
129 * If \a first_enq is 0 (ie, called from ldlm_reprocess_queue):
130 * - blocking ASTs have already been sent
132 * If \a first_enq is 1 (ie, called from ldlm_lock_enqueue):
133 * - blocking ASTs have not been sent yet, so list of conflicting locks
134 * would be collected and ASTs sent.
136 int ldlm_process_plain_lock(struct ldlm_lock *lock, __u64 *flags,
137 int first_enq, ldlm_error_t *err,
138 struct list_head *work_list)
140 struct ldlm_resource *res = lock->l_resource;
141 struct list_head rpc_list;
145 LASSERT(lock->l_granted_mode != lock->l_req_mode);
146 check_res_locked(res);
147 LASSERT(list_empty(&res->lr_converting));
148 INIT_LIST_HEAD(&rpc_list);
151 LASSERT(work_list != NULL);
152 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
154 RETURN(LDLM_ITER_STOP);
155 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
157 RETURN(LDLM_ITER_STOP);
159 ldlm_resource_unlink_lock(lock);
160 ldlm_grant_lock(lock, work_list);
161 RETURN(LDLM_ITER_CONTINUE);
165 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
166 rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
169 /* If either of the compat_queue()s returned 0, then we
170 * have ASTs to send and must go onto the waiting list.
172 * bug 2322: we used to unlink and re-add here, which was a
173 * terrible folly -- if we goto restart, we could get
174 * re-ordered! Causes deadlock, because ASTs aren't sent! */
175 if (list_empty(&lock->l_res_link))
176 ldlm_resource_add_lock(res, &res->lr_waiting, lock);
178 rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list,
183 *flags |= LDLM_FL_BLOCK_GRANTED;
185 ldlm_resource_unlink_lock(lock);
186 ldlm_grant_lock(lock, NULL);
190 #endif /* HAVE_SERVER_SUPPORT */
192 void ldlm_plain_policy_wire_to_local(const ldlm_wire_policy_data_t *wpolicy,
193 ldlm_policy_data_t *lpolicy)
195 /* No policy for plain locks */
198 void ldlm_plain_policy_local_to_wire(const ldlm_policy_data_t *lpolicy,
199 ldlm_wire_policy_data_t *wpolicy)
201 /* No policy for plain locks */