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 Lustre, http://www.lustre.org.
   9  *
  10  *   Lustre is free software; you can redistribute it and/or
  11  *   modify it under the terms of version 2 of the GNU General Public
  12  *   License as published by the Free Software Foundation.
  13  *
  14  *   Lustre is distributed in the hope that it will be useful,
  15  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *   GNU General Public License for more details.
  18  *
  19  *   You should have received a copy of the GNU General Public License
  20  *   along with Lustre; if not, write to the Free Software
  21  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22  */
  23
  24 #define DEBUG_SUBSYSTEM S_LDLM
  25
  26 #ifdef __KERNEL__
  27 #include <linux/lustre_dlm.h>
  28 #include <linux/obd_support.h>
  29 #include <linux/lustre_lib.h>
  30 #else
  31 #include <liblustre.h>
  32 #endif
  33
  34 #include "ldlm_internal.h"
  35
  36 static inline int
  37 ldlm_plain_compat_queue(struct list_head *queue, struct ldlm_lock *req,
  38                         int send_cbs)
  39 {
  40         struct list_head *tmp;
  41         struct ldlm_lock *lock;
  42         ldlm_mode_t req_mode = req->l_req_mode;
  43         int compat = 1;
  44         ENTRY;
  45
  46         list_for_each(tmp, queue) {
  47                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
  48
  49                 if (req == lock)
  50                         RETURN(compat);
  51
  52                 if (lockmode_compat(lock->l_req_mode, req_mode))
  53                         continue;
  54
  55                 if (!send_cbs)
  56                         RETURN(0);
  57
  58                 compat = 0;
  59                 if (lock->l_blocking_ast)
  60                         ldlm_add_ast_work_item(lock, req, NULL, 0);
  61         }
  62
  63         RETURN(compat);
  64 }
  65
  66 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
  67  *   - blocking ASTs have already been sent
  68  *   - the caller has already initialized req->lr_tmp
  69  *   - must call this function with the ns lock held
  70  *
  71  * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
  72  *   - blocking ASTs have not been sent
  73  *   - the caller has NOT initialized req->lr_tmp, so we must
  74  *   - must call this function with the ns lock held once */
  75 int ldlm_process_plain_lock(struct ldlm_lock *lock, int *flags, int first_enq,
  76                             ldlm_error_t *err)
  77 {
  78         struct ldlm_resource *res = lock->l_resource;
  79         struct list_head rpc_list = LIST_HEAD_INIT(rpc_list);
  80         int rc;
  81         ENTRY;
  82
  83         LASSERT(list_empty(&res->lr_converting));
  84
  85         if (!first_enq) {
  86                 LASSERT(res->lr_tmp != NULL);
  87                 rc = ldlm_plain_compat_queue(&res->lr_granted, lock, 0);
  88                 if (!rc)
  89                         RETURN(LDLM_ITER_STOP);
  90                 rc = ldlm_plain_compat_queue(&res->lr_waiting, lock, 0);
  91                 if (!rc)
  92                         RETURN(LDLM_ITER_STOP);
  93
  94                 ldlm_resource_unlink_lock(lock);
  95                 ldlm_grant_lock(lock, NULL, 0, 1);
  96                 RETURN(LDLM_ITER_CONTINUE);
  97         }
  98
  99  restart:
 100         LASSERT(res->lr_tmp == NULL);
 101         res->lr_tmp = &rpc_list;
 102         rc = ldlm_plain_compat_queue(&res->lr_granted, lock, 1);
 103         rc += ldlm_plain_compat_queue(&res->lr_waiting, lock, 1);
 104         res->lr_tmp = NULL;
 105
 106         if (rc != 2) {
 107                 /* If either of the compat_queue()s returned 0, then we
 108                  * have ASTs to send and must go onto the waiting list. */
 109                 ldlm_resource_unlink_lock(lock);
 110                 ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 111                 l_unlock(&res->lr_namespace->ns_lock);
 112                 rc = ldlm_run_ast_work(res->lr_namespace, &rpc_list);
 113                 l_lock(&res->lr_namespace->ns_lock);
 114                 if (rc == -ERESTART)
 115                         GOTO(restart, -ERESTART);
 116                 *flags |= LDLM_FL_BLOCK_GRANTED;
 117         } else {
 118                 ldlm_resource_unlink_lock(lock);
 119                 ldlm_grant_lock(lock, NULL, 0, 0);
 120         }
 121         RETURN(0);
 122 }