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7 * it under the terms of the GNU General Public License version 2 only,
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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
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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, 2013, 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 enum ldlm_mode req_mode = req->l_req_mode;
76 struct ldlm_lock *lock, *next_lock;
80 lockmode_verify(req_mode);
82 list_for_each_entry_safe(lock, next_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 next_lock = list_entry(list_entry(lock->l_sl_mode.prev,
93 l_sl_mode)->l_res_link.next,
94 struct ldlm_lock, l_res_link);
96 if (lockmode_compat(lock->l_req_mode, req_mode))
104 /* Add locks of the mode group to \a work_list as
105 * blocking locks for \a req. */
106 if (lock->l_blocking_ast)
107 ldlm_add_ast_work_item(lock, req, work_list);
110 struct list_head *head;
112 head = &lock->l_sl_mode;
113 list_for_each_entry(lock, head, l_sl_mode)
114 if (lock->l_blocking_ast)
115 ldlm_add_ast_work_item(lock, req,
124 * Process a granting attempt for plain lock.
125 * Must be called with ns lock held.
127 * This function looks for any conflicts for \a lock in the granted or
128 * waiting queues. The lock is granted if no conflicts are found in
131 * If \a first_enq is 0 (ie, called from ldlm_reprocess_queue):
132 * - blocking ASTs have already been sent
134 * If \a first_enq is 1 (ie, called from ldlm_lock_enqueue):
135 * - blocking ASTs have not been sent yet, so list of conflicting locks
136 * would be collected and ASTs sent.
138 int ldlm_process_plain_lock(struct ldlm_lock *lock, __u64 *flags,
139 int first_enq, enum ldlm_error *err,
140 struct list_head *work_list)
142 struct ldlm_resource *res = lock->l_resource;
143 struct list_head rpc_list;
147 LASSERT(lock->l_granted_mode != lock->l_req_mode);
148 check_res_locked(res);
149 LASSERT(list_empty(&res->lr_converting));
150 INIT_LIST_HEAD(&rpc_list);
153 LASSERT(work_list != NULL);
154 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
156 RETURN(LDLM_ITER_STOP);
157 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
159 RETURN(LDLM_ITER_STOP);
161 ldlm_resource_unlink_lock(lock);
162 ldlm_grant_lock(lock, work_list);
163 RETURN(LDLM_ITER_CONTINUE);
167 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
168 rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
171 /* If either of the compat_queue()s returned 0, then we
172 * have ASTs to send and must go onto the waiting list.
174 * bug 2322: we used to unlink and re-add here, which was a
175 * terrible folly -- if we goto restart, we could get
176 * re-ordered! Causes deadlock, because ASTs aren't sent! */
177 if (list_empty(&lock->l_res_link))
178 ldlm_resource_add_lock(res, &res->lr_waiting, lock);
180 rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list,
185 *flags |= LDLM_FL_BLOCK_GRANTED;
187 ldlm_resource_unlink_lock(lock);
188 ldlm_grant_lock(lock, NULL);
192 #endif /* HAVE_SERVER_SUPPORT */
194 void ldlm_plain_policy_wire_to_local(const union ldlm_wire_policy_data *wpolicy,
195 union ldlm_policy_data *lpolicy)
197 /* No policy for plain locks */
200 void ldlm_plain_policy_local_to_wire(const union ldlm_policy_data *lpolicy,
201 union ldlm_wire_policy_data *wpolicy)
203 /* No policy for plain locks */