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  * 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
  20  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  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 (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  30  * Use is subject to license terms.
  31  *
  32  * Copyright (c) 2011, Whamcloud, Inc.
  33  */
  34 /*
  35  * This file is part of Lustre, http://www.lustre.org/
  36  * Lustre is a trademark of Sun Microsystems, Inc.
  37  *
  38  * lustre/ldlm/ldlm_plain.c
  39  *
  40  * Author: Peter Braam <braam@clusterfs.com>
  41  * Author: Phil Schwan <phil@clusterfs.com>
  42  */
  43
  44 #define DEBUG_SUBSYSTEM S_LDLM
  45
  46 #ifdef __KERNEL__
  47 #include <lustre_dlm.h>
  48 #include <obd_support.h>
  49 #include <lustre_lib.h>
  50 #else
  51 #include <liblustre.h>
  52 #endif
  53
  54 #include "ldlm_internal.h"
  55
  56 static inline int
  57 ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req,
  58                         cfs_list_t *work_list)
  59 {
  60         cfs_list_t *tmp;
  61         struct ldlm_lock *lock;
  62         ldlm_mode_t req_mode = req->l_req_mode;
  63         int compat = 1;
  64         ENTRY;
  65
  66         lockmode_verify(req_mode);
  67
  68         cfs_list_for_each(tmp, queue) {
  69                 lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link);
  70
  71                 if (req == lock)
  72                         RETURN(compat);
  73
  74                  /* last lock in mode group */
  75                  tmp = &cfs_list_entry(lock->l_sl_mode.prev,
  76                                        struct ldlm_lock,
  77                                        l_sl_mode)->l_res_link;
  78
  79                  if (lockmode_compat(lock->l_req_mode, req_mode))
  80                         continue;
  81
  82                 if (!work_list)
  83                         RETURN(0);
  84
  85                 compat = 0;
  86
  87                 /* add locks of the mode group to @work_list as
  88                  * blocking locks for @req */
  89                 if (lock->l_blocking_ast)
  90                         ldlm_add_ast_work_item(lock, req, work_list);
  91
  92                 {
  93                         cfs_list_t *head;
  94
  95                         head = &lock->l_sl_mode;
  96                         cfs_list_for_each_entry(lock, head, l_sl_mode)
  97                                 if (lock->l_blocking_ast)
  98                                         ldlm_add_ast_work_item(lock, req,
  99                                                                work_list);
 100                 }
 101         }
 102
 103         RETURN(compat);
 104 }
 105
 106 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 107  *   - blocking ASTs have already been sent
 108  *   - must call this function with the resource lock held
 109  *
 110  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 111  *   - blocking ASTs have not been sent
 112  *   - must call this function with the resource lock held */
 113 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
 114                             ldlm_error_t *err, cfs_list_t *work_list)
 115 {
 116         struct ldlm_resource *res = lock->l_resource;
 117         CFS_LIST_HEAD(rpc_list);
 118         int rc;
 119         ENTRY;
 120
 121         check_res_locked(res);
 122         LASSERT(cfs_list_empty(&res->lr_converting));
 123
 124         if (!first_enq) {
 125                 LASSERT(work_list != NULL);
 126                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
 127                 if (!rc)
 128                         RETURN(LDLM_ITER_STOP);
 129                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
 130                 if (!rc)
 131                         RETURN(LDLM_ITER_STOP);
 132
 133                 ldlm_resource_unlink_lock(lock);
 134                 ldlm_grant_lock(lock, work_list);
 135                 RETURN(LDLM_ITER_CONTINUE);
 136         }
 137
 138  restart:
 139         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
 140         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
 141
 142         if (rc != 2) {
 143                 /* If either of the compat_queue()s returned 0, then we
 144                  * have ASTs to send and must go onto the waiting list.
 145                  *
 146                  * bug 2322: we used to unlink and re-add here, which was a
 147                  * terrible folly -- if we goto restart, we could get
 148                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 149                 if (cfs_list_empty(&lock->l_res_link))
 150                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 151                 unlock_res(res);
 152                 rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list,
 153                                        LDLM_WORK_BL_AST);
 154                 lock_res(res);
 155                 if (rc == -ERESTART)
 156                         GOTO(restart, -ERESTART);
 157                 *flags |= LDLM_FL_BLOCK_GRANTED;
 158         } else {
 159                 ldlm_resource_unlink_lock(lock);
 160                 ldlm_grant_lock(lock, NULL);
 161         }
 162         RETURN(0);
 163 }
 164
 165 void ldlm_plain_policy_wire_to_local(const ldlm_wire_policy_data_t *wpolicy,
 166                                      ldlm_policy_data_t *lpolicy)
 167 {
 168         /* No policy for plain locks */
 169 }
 170
 171 void ldlm_plain_policy_local_to_wire(const ldlm_policy_data_t *lpolicy,
 172                                      ldlm_wire_policy_data_t *wpolicy)
 173 {
 174         /* No policy for plain locks */
 175 }