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[fs/lustre-release.git] / lustre / ldlm / ldlm_plain.c
1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
2  * vim:expandtab:shiftwidth=8:tabstop=8:
3  *
4  *  Copyright (c) 2002, 2003 Cluster File Systems, Inc.
5  *   Author: Peter Braam <braam@clusterfs.com>
6  *   Author: Phil Schwan <phil@clusterfs.com>
7  *
8  *   This file is part of the Lustre file system, http://www.lustre.org
9  *   Lustre is a trademark of Cluster File Systems, Inc.
10  *
11  *   You may have signed or agreed to another license before downloading
12  *   this software.  If so, you are bound by the terms and conditions
13  *   of that agreement, and the following does not apply to you.  See the
14  *   LICENSE file included with this distribution for more information.
15  *
16  *   If you did not agree to a different license, then this copy of Lustre
17  *   is open source software; you can redistribute it and/or modify it
18  *   under the terms of version 2 of the GNU General Public License as
19  *   published by the Free Software Foundation.
20  *
21  *   In either case, Lustre is distributed in the hope that it will be
22  *   useful, but WITHOUT ANY WARRANTY; without even the implied warranty
23  *   of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
24  *   license text for more details.
25  */
26
27 #define DEBUG_SUBSYSTEM S_LDLM
28
29 #ifdef __KERNEL__
30 #include <lustre_dlm.h>
31 #include <obd_support.h>
32 #include <lustre_lib.h>
33 #else
34 #include <liblustre.h>
35 #endif
36
37 #include "ldlm_internal.h"
38
39 static inline int
40 ldlm_plain_compat_queue(struct list_head *queue, struct ldlm_lock *req,
41                         struct list_head *work_list)
42 {
43         struct list_head *tmp;
44         struct ldlm_lock *lock;
45         ldlm_mode_t req_mode = req->l_req_mode;
46         int compat = 1;
47         ENTRY;
48
49         lockmode_verify(req_mode);
50
51         list_for_each(tmp, queue) {
52                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
53
54                 if (req == lock)
55                         RETURN(compat);
56
57                 if (lockmode_compat(lock->l_req_mode, req_mode)) {
58                         /* jump to next mode group */
59                         if (LDLM_SL_HEAD(&lock->l_sl_mode))
60                                 tmp = &list_entry(lock->l_sl_mode.next, 
61                                                   struct ldlm_lock,
62                                                   l_sl_mode)->l_res_link;
63                         continue;
64                 }
65
66                 if (!work_list)
67                         RETURN(0);
68
69                 compat = 0;
70                 if (lock->l_blocking_ast)
71                         ldlm_add_ast_work_item(lock, req, work_list);
72
73                 if (LDLM_SL_HEAD(&lock->l_sl_mode)) {
74                         /* add all members of the mode group */
75                         do {
76                                 tmp = lock->l_res_link.next;
77                                 lock = list_entry(tmp, struct ldlm_lock, 
78                                                   l_res_link);
79                                 if (lock->l_blocking_ast)
80                                         ldlm_add_ast_work_item(
81                                                         lock, req, work_list);
82                         } while (!LDLM_SL_TAIL(&lock->l_sl_mode));
83                 }
84         }
85
86         RETURN(compat);
87 }
88
89 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
90  *   - blocking ASTs have already been sent
91  *   - must call this function with the resource lock held
92  *
93  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
94  *   - blocking ASTs have not been sent
95  *   - must call this function with the resource lock held */
96 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
97                             ldlm_error_t *err, struct list_head *work_list)
98 {
99         struct ldlm_resource *res = lock->l_resource;
100         struct list_head rpc_list = CFS_LIST_HEAD_INIT(rpc_list);
101         int rc;
102         ENTRY;
103
104         check_res_locked(res);
105         LASSERT(list_empty(&res->lr_converting));
106
107         if (!first_enq) {
108                 LASSERT(work_list != NULL);
109                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
110                 if (!rc)
111                         RETURN(LDLM_ITER_STOP);
112                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
113                 if (!rc)
114                         RETURN(LDLM_ITER_STOP);
115
116                 ldlm_resource_unlink_lock(lock);
117                 ldlm_grant_lock(lock, work_list);
118                 RETURN(LDLM_ITER_CONTINUE);
119         }
120
121  restart:
122         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
123         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
124
125         if (rc != 2) {
126                 /* If either of the compat_queue()s returned 0, then we
127                  * have ASTs to send and must go onto the waiting list.
128                  *
129                  * bug 2322: we used to unlink and re-add here, which was a
130                  * terrible folly -- if we goto restart, we could get
131                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
132                 if (list_empty(&lock->l_res_link))
133                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
134                 unlock_res(res);
135                 rc = ldlm_run_bl_ast_work(&rpc_list);
136                 lock_res(res);
137                 if (rc == -ERESTART)
138                         GOTO(restart, -ERESTART);
139                 *flags |= LDLM_FL_BLOCK_GRANTED;
140         } else {
141                 ldlm_resource_unlink_lock(lock);
142                 ldlm_grant_lock(lock, NULL);
143         }
144         RETURN(0);
145 }