lustre/ldlm/ldlm_inodebits.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * GPL HEADER START
   5  *
   6  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 only,
  10  * as published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License version 2 for more details (a copy is included
  16  * in the LICENSE file that accompanied this code).
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * version 2 along with this program; If not, see [sun.com URL with a
  20  * copy of GPLv2].
  21  *
  22  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  23  * CA 95054 USA or visit www.sun.com if you need additional information or
  24  * have any questions.
  25  *
  26  * GPL HEADER END
  27  */
  28 /*
  29  * Copyright  2008 Sun Microsystems, Inc. All rights reserved
  30  * Use is subject to license terms.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  *
  36  * lustre/ldlm/ldlm_inodebits.c
  37  *
  38  * Author: Peter Braam <braam@clusterfs.com>
  39  * Author: Phil Schwan <phil@clusterfs.com>
  40  */
  41
  42 #define DEBUG_SUBSYSTEM S_LDLM
  43 #ifndef __KERNEL__
  44 # include <liblustre.h>
  45 #endif
  46
  47 #include <lustre_dlm.h>
  48 #include <obd_support.h>
  49 #include <lustre_lib.h>
  50
  51 #include "ldlm_internal.h"
  52
  53 /* Determine if the lock is compatible with all locks on the queue. */
  54 static int
  55 ldlm_inodebits_compat_queue(struct list_head *queue, struct ldlm_lock *req,
  56                             struct list_head *work_list)
  57 {
  58         struct list_head *tmp;
  59         struct ldlm_lock *lock;
  60         ldlm_mode_t req_mode = req->l_req_mode;
  61         __u64 req_bits = req->l_policy_data.l_inodebits.bits;
  62         int compat = 1;
  63         ENTRY;
  64
  65         LASSERT(req_bits); /* There is no sense in lock with no bits set,
  66                               I think. Also such a lock would be compatible
  67                                with any other bit lock */
  68
  69         list_for_each(tmp, queue) {
  70                 struct list_head *mode_tail;
  71
  72                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
  73
  74                 if (req == lock)
  75                         RETURN(compat);
  76
  77                 /* last lock in mode group */
  78                 LASSERT(lock->l_sl_mode.prev != NULL);
  79                 mode_tail = &list_entry(lock->l_sl_mode.prev,
  80                                         struct ldlm_lock,
  81                                         l_sl_mode)->l_res_link;
  82
  83                 /* locks are compatible, bits don't matter */
  84                 if (lockmode_compat(lock->l_req_mode, req_mode)) {
  85                         /* jump to last lock in mode group */
  86                         tmp = mode_tail;
  87                         continue;
  88                 }
  89
  90                 for (;;) {
  91                         struct list_head *head;
  92
  93                         /* last lock in policy group */
  94                         tmp = &list_entry(lock->l_sl_policy.prev,
  95                                           struct ldlm_lock,
  96                                           l_sl_policy)->l_res_link;
  97
  98                         /* locks with bits overlapped are conflicting locks */
  99                         if (lock->l_policy_data.l_inodebits.bits & req_bits) {
 100                                 /* conflicting policy */
 101                                 if (!work_list)
 102                                         RETURN(0);
 103
 104                                 compat = 0;
 105
 106                                 /* add locks of the policy group to
 107                                  * @work_list as blocking locks for
 108                                  * @req */
 109                                 if (lock->l_blocking_ast)
 110                                         ldlm_add_ast_work_item(lock, req,
 111                                                                work_list);
 112                                 head = &lock->l_sl_policy;
 113                                 list_for_each_entry(lock, head, l_sl_policy)
 114                                         if (lock->l_blocking_ast)
 115                                                 ldlm_add_ast_work_item(lock, req,
 116                                                                        work_list);
 117                         }
 118                         if (tmp == mode_tail)
 119                                 break;
 120
 121                         tmp = tmp->next;
 122                         lock = list_entry(tmp, struct ldlm_lock, l_res_link);
 123                 } /* loop over policy groups within one mode group */
 124         } /* loop over mode groups within @queue */
 125
 126         RETURN(compat);
 127 }
 128
 129 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 130   *   - blocking ASTs have already been sent
 131   *   - must call this function with the ns lock held
 132   *
 133   * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 134   *   - blocking ASTs have not been sent
 135   *   - must call this function with the ns lock held once */
 136 int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags,
 137                                 int first_enq, ldlm_error_t *err,
 138                                 struct list_head *work_list)
 139 {
 140         struct ldlm_resource *res = lock->l_resource;
 141         CFS_LIST_HEAD(rpc_list);
 142         int rc;
 143         ENTRY;
 144
 145         LASSERT(list_empty(&res->lr_converting));
 146         check_res_locked(res);
 147
 148         if (!first_enq) {
 149                 LASSERT(work_list != NULL);
 150                 rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, NULL);
 151                 if (!rc)
 152                         RETURN(LDLM_ITER_STOP);
 153                 rc = ldlm_inodebits_compat_queue(&res->lr_waiting, lock, NULL);
 154                 if (!rc)
 155                         RETURN(LDLM_ITER_STOP);
 156
 157                 ldlm_resource_unlink_lock(lock);
 158                 ldlm_grant_lock(lock, work_list);
 159                 RETURN(LDLM_ITER_CONTINUE);
 160         }
 161
 162  restart:
 163         rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, &rpc_list);
 164         rc += ldlm_inodebits_compat_queue(&res->lr_waiting, lock, &rpc_list);
 165
 166         if (rc != 2) {
 167                 /* If either of the compat_queue()s returned 0, then we
 168                  * have ASTs to send and must go onto the waiting list.
 169                  *
 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);
 175                 unlock_res(res);
 176                 rc = ldlm_run_ast_work(&rpc_list, LDLM_WORK_BL_AST);
 177                 lock_res(res);
 178                 if (rc == -ERESTART)
 179                         GOTO(restart, -ERESTART);
 180                 *flags |= LDLM_FL_BLOCK_GRANTED;
 181         } else {
 182                 ldlm_resource_unlink_lock(lock);
 183                 ldlm_grant_lock(lock, NULL);
 184         }
 185         RETURN(0);
 186 }