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  *   - the caller has already initialized req->lr_tmp
  92  *   - must call this function with the resource lock held
  93  *
  94  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
  95  *   - blocking ASTs have not been sent
  96  *   - the caller has NOT initialized req->lr_tmp, so we must
  97  *   - must call this function with the resource lock held */
  98 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
  99                             ldlm_error_t *err, struct list_head *work_list)
 100 {
 101         struct ldlm_resource *res = lock->l_resource;
 102         struct list_head rpc_list = CFS_LIST_HEAD_INIT(rpc_list);
 103         int rc;
 104         ENTRY;
 105
 106         check_res_locked(res);
 107         LASSERT(list_empty(&res->lr_converting));
 108
 109         if (!first_enq) {
 110                 LASSERT(work_list != NULL);
 111                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, NULL);
 112                 if (!rc)
 113                         RETURN(LDLM_ITER_STOP);
 114                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, NULL);
 115                 if (!rc)
 116                         RETURN(LDLM_ITER_STOP);
 117
 118                 ldlm_resource_unlink_lock(lock);
 119                 ldlm_grant_lock(lock, work_list);
 120                 RETURN(LDLM_ITER_CONTINUE);
 121         }
 122
 123  restart:
 124         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, &rpc_list);
 125         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, &rpc_list);
 126
 127         if (rc != 2) {
 128                 /* If either of the compat_queue()s returned 0, then we
 129                  * have ASTs to send and must go onto the waiting list.
 130                  *
 131                  * bug 2322: we used to unlink and re-add here, which was a
 132                  * terrible folly -- if we goto restart, we could get
 133                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 134                 if (list_empty(&lock->l_res_link))
 135                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 136                 unlock_res(res);
 137                 rc = ldlm_run_bl_ast_work(&rpc_list);
 138                 lock_res(res);
 139                 if (rc == -ERESTART)
 140                         GOTO(restart, -ERESTART);
 141                 *flags |= LDLM_FL_BLOCK_GRANTED;
 142         } else {
 143                 ldlm_resource_unlink_lock(lock);
 144                 ldlm_grant_lock(lock, NULL);
 145         }
 146         RETURN(0);
 147 }