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;
  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
  51         list_for_each(tmp, queue) {
  52                 struct list_head *mode_tail;
  53
  54                 lock = list_entry(tmp, struct ldlm_lock, l_res_link);
  55
  56                 if (req == lock)
  57                         RETURN(compat);
  58
  59                 /* last lock in mode group */
  60                 LASSERT(lock->l_sl_mode.prev != NULL);
  61                 mode_tail = &list_entry(lock->l_sl_mode.prev,
  62                                         struct ldlm_lock,
  63                                         l_sl_mode)->l_res_link;
  64
  65                 /* locks are compatible, bits don't matter */
  66                 if (lockmode_compat(lock->l_req_mode, req_mode)) {
  67                         /* jump to last lock in mode group */
  68                         tmp = mode_tail;
  69                         continue;
  70                 }
  71
  72                 for (;;) {
  73                         struct list_head *head;
  74
  75                         /* last lock in policy group */
  76                         tmp = &list_entry(lock->l_sl_policy.prev,
  77                                           struct ldlm_lock,
  78                                           l_sl_policy)->l_res_link;
  79
  80                         /* locks with bits overlapped are conflicting locks */
  81                         if (lock->l_policy_data.l_inodebits.bits & req_bits) {
  82                                 /* conflicting policy */
  83                                 if (!work_list)
  84                                         RETURN(0);
  85
  86                                 compat = 0;
  87
  88                                 /* add locks of the policy group to
  89                                  * @work_list as blocking locks for
  90                                  * @req */
  91                                 if (lock->l_blocking_ast)
  92                                         ldlm_add_ast_work_item(lock, req,
  93                                                                work_list);
  94                                 head = &lock->l_sl_policy;
  95                                 list_for_each_entry(lock, head, l_sl_policy)
  96                                         if (lock->l_blocking_ast)
  97                                                 ldlm_add_ast_work_item(lock, req,
  98                                                                        work_list);
  99                         }
 100                         if (tmp == mode_tail)
 101                                 break;
 102
 103                         tmp = tmp->next;
 104                         lock = list_entry(tmp, struct ldlm_lock, l_res_link);
 105                 } /* loop over policy groups within one mode group */
 106         } /* loop over mode groups within @queue */
 107
 108         RETURN(compat);
 109 }
 110
 111 /* If first_enq is 0 (ie, called from ldlm_reprocess_queue):
 112   *   - blocking ASTs have already been sent
 113   *   - must call this function with the ns lock held
 114   *
 115   * If first_enq is 1 (ie, called from ldlm_lock_enqueue):
 116   *   - blocking ASTs have not been sent
 117   *   - must call this function with the ns lock held once */
 118 int ldlm_process_inodebits_lock(struct ldlm_lock *lock, int *flags,
 119                                 int first_enq, ldlm_error_t *err,
 120                                 struct list_head *work_list)
 121 {
 122         struct ldlm_resource *res = lock->l_resource;
 123         CFS_LIST_HEAD(rpc_list);
 124         int rc;
 125         ENTRY;
 126
 127         LASSERT(list_empty(&res->lr_converting));
 128         check_res_locked(res);
 129
 130         if (!first_enq) {
 131                 LASSERT(work_list != NULL);
 132                 rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, NULL);
 133                 if (!rc)
 134                         RETURN(LDLM_ITER_STOP);
 135                 rc = ldlm_inodebits_compat_queue(&res->lr_waiting, lock, NULL);
 136                 if (!rc)
 137                         RETURN(LDLM_ITER_STOP);
 138
 139                 ldlm_resource_unlink_lock(lock);
 140                 ldlm_grant_lock(lock, work_list);
 141                 RETURN(LDLM_ITER_CONTINUE);
 142         }
 143
 144  restart:
 145         rc = ldlm_inodebits_compat_queue(&res->lr_granted, lock, &rpc_list);
 146         rc += ldlm_inodebits_compat_queue(&res->lr_waiting, lock, &rpc_list);
 147
 148         if (rc != 2) {
 149                 /* If either of the compat_queue()s returned 0, then we
 150                  * have ASTs to send and must go onto the waiting list.
 151                  *
 152                  * bug 2322: we used to unlink and re-add here, which was a
 153                  * terrible folly -- if we goto restart, we could get
 154                  * re-ordered!  Causes deadlock, because ASTs aren't sent! */
 155                 if (list_empty(&lock->l_res_link))
 156                         ldlm_resource_add_lock(res, &res->lr_waiting, lock);
 157                 unlock_res(res);
 158                 rc = ldlm_run_ast_work(&rpc_list, LDLM_WORK_BL_AST);
 159                 lock_res(res);
 160                 if (rc == -ERESTART)
 161                         GOTO(restart, -ERESTART);
 162                 *flags |= LDLM_FL_BLOCK_GRANTED;
 163         } else {
 164                 ldlm_resource_unlink_lock(lock);
 165                 ldlm_grant_lock(lock, NULL);
 166         }
 167         RETURN(0);
 168 }