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 /*
  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_plain.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
  44 #ifdef __KERNEL__
  45 #include <lustre_dlm.h>
  46 #include <obd_support.h>
  47 #include <lustre_lib.h>
  48 #else
  49 #include <liblustre.h>
  50 #endif
  51
  52 #include "ldlm_internal.h"
  53
  54 static inline int
  55 ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req,
  56                         cfs_list_t *work_list)
  57 {
  58         cfs_list_t *tmp;
  59         struct ldlm_lock *lock;
  60         ldlm_mode_t req_mode = req->l_req_mode;
  61         int compat = 1;
  62         ENTRY;
  63
  64         lockmode_verify(req_mode);
  65
  66         cfs_list_for_each(tmp, queue) {
  67                 lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link);
  68
  69                 if (req == lock)
  70                         RETURN(compat);
  71
  72                  /* last lock in mode group */
  73                  tmp = &cfs_list_entry(lock->l_sl_mode.prev,
  74                                        struct ldlm_lock,
  75                                        l_sl_mode)->l_res_link;
  76
  77                  if (lockmode_compat(lock->l_req_mode, req_mode))
  78                         continue;
  79
  80                 if (!work_list)
  81                         RETURN(0);
  82
  83                 compat = 0;
  84
  85                 /* add locks of the mode group to @work_list as
  86                  * blocking locks for @req */
  87                 if (lock->l_blocking_ast)
  88                         ldlm_add_ast_work_item(lock, req, work_list);
  89
  90                 {
  91                         cfs_list_t *head;
  92
  93                         head = &lock->l_sl_mode;
  94                         cfs_list_for_each_entry(lock, head, l_sl_mode)
  95                                 if (lock->l_blocking_ast)
  96                                         ldlm_add_ast_work_item(lock, req,
  97                                                                work_list);
  98                 }
  99         }
 100
 101         RETURN(compat);
 102 }
 103
 104 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 105  *   - blocking ASTs have already been sent
 106  *   - must call this function with the resource lock held
 107  *
 108  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 109  *   - blocking ASTs have not been sent
 110  *   - must call this function with the resource lock held */
 111 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
 112                             ldlm_error_t *err, cfs_list_t *work_list)
 113 {
 114         struct ldlm_resource *res = lock->l_resource;
 115         CFS_LIST_HEAD(rpc_list);
 116         int rc;
 117         ENTRY;
 118
 119         check_res_locked(res);
 120         LASSERT(cfs_list_empty(&res->lr_converting));
 121
 122         if (!first_enq) {
 123                 LASSERT(work_list != NULL);
 124                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
 125                 if (!rc)
 126                         RETURN(LDLM_ITER_STOP);
 127                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
 128                 if (!rc)
 129                         RETURN(LDLM_ITER_STOP);
 130
 131                 ldlm_resource_unlink_lock(lock);
 132                 ldlm_grant_lock(lock, work_list);
 133                 RETURN(LDLM_ITER_CONTINUE);
 134         }
 135
 136  restart:
 137         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
 138         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
 139
 140         if (rc != 2) {
 141                 /* If either of the compat_queue()s returned 0, then we
 142                  * have ASTs to send and must go onto the waiting list.
 143                  *
 144                  * bug 2322: we used to unlink and re-add here, which was a
 145                  * terrible folly -- if we goto restart, we could get
 146                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 147                 if (cfs_list_empty(&lock->l_res_link))
 148                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 149                 unlock_res(res);
 150                 rc = ldlm_run_ast_work(&rpc_list, LDLM_WORK_BL_AST);
 151                 lock_res(res);
 152                 if (rc == -ERESTART)
 153                         GOTO(restart, -ERESTART);
 154                 *flags |= LDLM_FL_BLOCK_GRANTED;
 155         } else {
 156                 ldlm_resource_unlink_lock(lock);
 157                 ldlm_grant_lock(lock, NULL);
 158         }
 159         RETURN(0);
 160 }