lustre/ldlm/ldlm_inodebits.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, 2004 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 #ifndef __KERNEL__
  26 # include <liblustre.h>
  27 #endif
  28
  29 #include <lustre_dlm.h>
  30 #include <obd_support.h>
  31 #include <lustre_lib.h>
  32
  33 #include "ldlm_internal.h"
  34
  35 /* Determine if the lock is compatible with all locks on the queue. */
  36 static int
  37 ldlm_inodebits_compat_queue(struct list_head *queue, struct ldlm_lock *req,
  38                             struct list_head *work_list)
  39 {
  40         struct list_head *tmp, *tmp_tail;
  41         struct ldlm_lock *lock;
  42         ldlm_mode_t req_mode = req->l_req_mode;
  43         __u64 req_bits = req->l_policy_data.l_inodebits.bits;
  44         int compat = 1;
  45         ENTRY;
  46
  47         LASSERT(req_bits); /* There is no sense in lock with no bits set,
  48                               I think. Also such a lock would be compatible
  49                                with any other bit lock */
  50         list_for_each(tmp, queue) {
  51                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
  52
  53                 if (req == lock)
  54                         RETURN(compat);
  55
  56                 /* locks are compatible, bits don't matter */
  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                 tmp_tail = tmp;
  67                 if (LDLM_SL_HEAD(&lock->l_sl_mode))
  68                         tmp_tail = &list_entry(lock->l_sl_mode.next,
  69                                                struct ldlm_lock,
  70                                                l_sl_mode)->l_res_link;
  71                 for (;;) {
  72                         /* locks with bits overlapped are conflicting locks */
  73                         if (lock->l_policy_data.l_inodebits.bits & req_bits) {
  74                                 /* conflicting policy */
  75                                 if (!work_list)
  76                                         RETURN(0);
  77
  78                                 compat = 0;
  79                                 if (lock->l_blocking_ast)
  80                                         ldlm_add_ast_work_item(lock, req,
  81                                                                work_list);
  82                                 /* add all members of the policy group */
  83                                 if (LDLM_SL_HEAD(&lock->l_sl_policy)) {
  84                                         do {
  85                                                 tmp = lock->l_res_link.next;
  86                                                 lock = list_entry(tmp,
  87                                                             struct ldlm_lock,
  88                                                             l_res_link);
  89                                                 if (lock->l_blocking_ast)
  90                                                         ldlm_add_ast_work_item(
  91                                                                      lock,
  92                                                                      req,
  93                                                                      work_list);
  94                                         } while (!LDLM_SL_TAIL(&lock->l_sl_policy));
  95                                 }
  96                         } else if (LDLM_SL_HEAD(&lock->l_sl_policy)) {
  97                                 /* jump to next policy group */
  98                                 tmp = &list_entry(lock->l_sl_policy.next,
  99                                                   struct ldlm_lock,
 100                                                   l_sl_policy)->l_res_link;
 101                         }
 102                         if (tmp == tmp_tail)
 103                                 break;
 104                         else
 105                                 tmp = tmp->next;
 106                         lock = list_entry(tmp, struct ldlm_lock, l_res_link);
 107                 }       /* for locks in a mode group */
 108         }       /* for each lock in the queue */
 109
 110         RETURN(compat);
 111 }
 112
 113 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 114   *   - blocking ASTs have already been sent
 115   *   - must call this function with the ns lock held
 116   *
 117   * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 118   *   - blocking ASTs have not been sent
 119   *   - must call this function with the ns lock held once */
 120 int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags,
 121                                 int first_enq, ldlm_error_t *err,
 122                                 struct list_head *work_list)
 123 {
 124         struct ldlm_resource *res = lock->l_resource;
 125         struct list_head rpc_list = CFS_LIST_HEAD_INIT(rpc_list);
 126         int rc;
 127         ENTRY;
 128
 129         LASSERT(list_empty(&res->lr_converting));
 130         check_res_locked(res);
 131
 132         if (!first_enq) {
 133                 LASSERT(work_list != NULL);
 134                 rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, NULL);
 135                 if (!rc)
 136                         RETURN(LDLM_ITER_STOP);
 137                 rc = ldlm_inodebits_compat_queue(&res->lr_waiting, lock, NULL);
 138                 if (!rc)
 139                         RETURN(LDLM_ITER_STOP);
 140
 141                 ldlm_resource_unlink_lock(lock);
 142                 ldlm_grant_lock(lock, work_list);
 143                 RETURN(LDLM_ITER_CONTINUE);
 144         }
 145
 146  restart:
 147         rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, &rpc_list);
 148         rc += ldlm_inodebits_compat_queue(&res->lr_waiting, lock, &rpc_list);
 149
 150         if (rc != 2) {
 151                 /* If either of the compat_queue()s returned 0, then we
 152                  * have ASTs to send and must go onto the waiting list.
 153                  *
 154                  * bug 2322: we used to unlink and re-add here, which was a
 155                  * terrible folly -- if we goto restart, we could get
 156                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 157                 if (list_empty(&lock->l_res_link))
 158                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 159                 unlock_res(res);
 160                 rc = ldlm_run_bl_ast_work(&rpc_list);
 161                 lock_res(res);
 162                 if (rc == -ERESTART)
 163                         GOTO(restart, -ERESTART);
 164                 *flags |= LDLM_FL_BLOCK_GRANTED;
 165         } else {
 166                 ldlm_resource_unlink_lock(lock);
 167                 ldlm_grant_lock(lock, NULL);
 168         }
 169         RETURN(0);
 170 }