lustre/ldlm/ldlm_plain.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  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).
  15  *
  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
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, Whamcloud, Inc.
  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 #ifdef HAVE_SERVER_SUPPORT
  55 static inline int
  56 ldlm_plain_compat_queue(cfs_list_t *queue, struct ldlm_lock *req,
  57                         cfs_list_t *work_list)
  58 {
  59         cfs_list_t *tmp;
  60         struct ldlm_lock *lock;
  61         ldlm_mode_t req_mode = req->l_req_mode;
  62         int compat = 1;
  63         ENTRY;
  64
  65         lockmode_verify(req_mode);
  66
  67         cfs_list_for_each(tmp, queue) {
  68                 lock = cfs_list_entry(tmp, struct ldlm_lock, l_res_link);
  69
  70                 if (req == lock)
  71                         RETURN(compat);
  72
  73                  /* last lock in mode group */
  74                  tmp = &cfs_list_entry(lock->l_sl_mode.prev,
  75                                        struct ldlm_lock,
  76                                        l_sl_mode)->l_res_link;
  77
  78                  if (lockmode_compat(lock->l_req_mode, req_mode))
  79                         continue;
  80
  81                 if (!work_list)
  82                         RETURN(0);
  83
  84                 compat = 0;
  85
  86                 /* add locks of the mode group to @work_list as
  87                  * blocking locks for @req */
  88                 if (lock->l_blocking_ast)
  89                         ldlm_add_ast_work_item(lock, req, work_list);
  90
  91                 {
  92                         cfs_list_t *head;
  93
  94                         head = &lock->l_sl_mode;
  95                         cfs_list_for_each_entry(lock, head, l_sl_mode)
  96                                 if (lock->l_blocking_ast)
  97                                         ldlm_add_ast_work_item(lock, req,
  98                                                                work_list);
  99                 }
 100         }
 101
 102         RETURN(compat);
 103 }
 104
 105 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 106  *   - blocking ASTs have already been sent
 107  *   - must call this function with the resource lock held
 108  *
 109  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 110  *   - blocking ASTs have not been sent
 111  *   - must call this function with the resource lock held */
 112 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
 113                             ldlm_error_t *err, cfs_list_t *work_list)
 114 {
 115         struct ldlm_resource *res = lock->l_resource;
 116         CFS_LIST_HEAD(rpc_list);
 117         int rc;
 118         ENTRY;
 119
 120         check_res_locked(res);
 121         LASSERT(cfs_list_empty(&res->lr_converting));
 122
 123         if (!first_enq) {
 124                 LASSERT(work_list != NULL);
 125                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
 126                 if (!rc)
 127                         RETURN(LDLM_ITER_STOP);
 128                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
 129                 if (!rc)
 130                         RETURN(LDLM_ITER_STOP);
 131
 132                 ldlm_resource_unlink_lock(lock);
 133                 ldlm_grant_lock(lock, work_list);
 134                 RETURN(LDLM_ITER_CONTINUE);
 135         }
 136
 137  restart:
 138         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
 139         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
 140
 141         if (rc != 2) {
 142                 /* If either of the compat_queue()s returned 0, then we
 143                  * have ASTs to send and must go onto the waiting list.
 144                  *
 145                  * bug 2322: we used to unlink and re-add here, which was a
 146                  * terrible folly -- if we goto restart, we could get
 147                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 148                 if (cfs_list_empty(&lock->l_res_link))
 149                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 150                 unlock_res(res);
 151                 rc = ldlm_run_ast_work(ldlm_res_to_ns(res), &rpc_list,
 152                                        LDLM_WORK_BL_AST);
 153                 lock_res(res);
 154                 if (rc == -ERESTART)
 155                         GOTO(restart, -ERESTART);
 156                 *flags |= LDLM_FL_BLOCK_GRANTED;
 157         } else {
 158                 ldlm_resource_unlink_lock(lock);
 159                 ldlm_grant_lock(lock, NULL);
 160         }
 161         RETURN(0);
 162 }
 163 #endif /* HAVE_SERVER_SUPPORT */
 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 }