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.gnu.org/licenses/gpl-2.0.html
23 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
24 * Use is subject to license terms.
26 * Copyright (c) 2011, 2013, Intel Corporation.
29 * This file is part of Lustre, http://www.lustre.org/
30 * Lustre is a trademark of Sun Microsystems, Inc.
32 * lustre/ldlm/ldlm_plain.c
34 * Author: Peter Braam <braam@clusterfs.com>
35 * Author: Phil Schwan <phil@clusterfs.com>
39 * This file contains implementation of PLAIN lock type.
41 * PLAIN locks are the simplest form of LDLM locking, and are used when
42 * there only needs to be a single lock on a resource. This avoids some
43 * of the complexity of EXTENT and IBITS lock types, but doesn't allow
44 * different "parts" of a resource to be locked concurrently. Example
45 * use cases for PLAIN locks include locking of MGS configuration logs
46 * and (as of Lustre 2.4) quota records.
49 #define DEBUG_SUBSYSTEM S_LDLM
51 #include <lustre_dlm.h>
52 #include <obd_support.h>
53 #include <lustre_lib.h>
55 #include "ldlm_internal.h"
57 #ifdef HAVE_SERVER_SUPPORT
59 * Determine if the lock is compatible with all locks on the queue.
61 * If \a work_list is provided, conflicting locks are linked there.
62 * If \a work_list is not provided, we exit this function on first conflict.
64 * \retval 0 if there are conflicting locks in the \a queue
65 * \retval 1 if the lock is compatible to all locks in \a queue
68 ldlm_plain_compat_queue(struct list_head *queue, struct ldlm_lock *req,
69 struct list_head *work_list)
71 enum ldlm_mode req_mode = req->l_req_mode;
72 struct ldlm_lock *lock, *next_lock;
76 lockmode_verify(req_mode);
78 list_for_each_entry_safe(lock, next_lock, queue, l_res_link) {
80 /* We stop walking the queue if we hit ourselves so we don't
81 * take conflicting locks enqueued after us into account,
82 * or we'd wait forever. */
86 /* Advance loop cursor to last lock of mode group. */
87 next_lock = list_entry(list_entry(lock->l_sl_mode.prev,
89 l_sl_mode)->l_res_link.next,
90 struct ldlm_lock, l_res_link);
92 if (lockmode_compat(lock->l_req_mode, req_mode))
100 /* Add locks of the mode group to \a work_list as
101 * blocking locks for \a req. */
102 if (lock->l_blocking_ast)
103 ldlm_add_ast_work_item(lock, req, work_list);
106 struct list_head *head;
108 head = &lock->l_sl_mode;
109 list_for_each_entry(lock, head, l_sl_mode)
110 if (lock->l_blocking_ast)
111 ldlm_add_ast_work_item(lock, req,
120 * Process a granting attempt for plain lock.
121 * Must be called with ns lock held.
123 * This function looks for any conflicts for \a lock in the granted or
124 * waiting queues. The lock is granted if no conflicts are found in
127 * If \a first_enq is 0 (ie, called from ldlm_reprocess_queue):
128 * - blocking ASTs have already been sent
130 * If \a first_enq is 1 (ie, called from ldlm_lock_enqueue):
131 * - blocking ASTs have not been sent yet, so list of conflicting locks
132 * would be collected and ASTs sent.
134 int ldlm_process_plain_lock(struct ldlm_lock *lock, __u64 *flags,
135 int first_enq, enum ldlm_error *err,
136 struct list_head *work_list)
138 struct ldlm_resource *res = lock->l_resource;
139 struct list_head rpc_list;
143 LASSERT(lock->l_granted_mode != lock->l_req_mode);
144 check_res_locked(res);
145 LASSERT(list_empty(&res->lr_converting));
146 INIT_LIST_HEAD(&rpc_list);
149 LASSERT(work_list != NULL);
150 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
152 RETURN(LDLM_ITER_STOP);
153 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
155 RETURN(LDLM_ITER_STOP);
157 ldlm_resource_unlink_lock(lock);
158 ldlm_grant_lock(lock, work_list);
159 RETURN(LDLM_ITER_CONTINUE);
163 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
164 rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
167 /* If either of the compat_queue()s returned 0, then we
168 * have ASTs to send and must go onto the waiting list.
170 * bug 2322: we used to unlink and re-add here, which was a
171 * terrible folly -- if we goto restart, we could get
172 * re-ordered! Causes deadlock, because ASTs aren't sent! */
173 if (list_empty(&lock->l_res_link))
174 ldlm_resource_add_lock(res, &res->lr_waiting, lock);
176 rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list,
179 if (rc == -ERESTART) {
180 /* We were granted while waiting, nothing left to do */
181 if (lock->l_granted_mode == lock->l_req_mode)
183 /* Lock was destroyed while we were waiting, abort */
184 if (ldlm_is_destroyed(lock))
185 GOTO(out, rc = -EAGAIN);
187 /* Otherwise try again */
190 *flags |= LDLM_FL_BLOCK_GRANTED;
192 ldlm_resource_unlink_lock(lock);
193 ldlm_grant_lock(lock, NULL);
199 LASSERT(list_empty(&rpc_list));
203 #endif /* HAVE_SERVER_SUPPORT */
205 void ldlm_plain_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
206 union ldlm_policy_data *lpolicy)
208 /* No policy for plain locks */
211 void ldlm_plain_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
212 union ldlm_wire_policy_data *wpolicy)
214 /* No policy for plain locks */