drivers/staging/lustre/lustre/ldlm/ldlm_extent.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) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2010, 2012, Intel Corporation.
  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_extent.c
  37  *
  38  * Author: Peter Braam <braam@clusterfs.com>
  39  * Author: Phil Schwan <phil@clusterfs.com>
  40  */
  41
  42 /**
  43  * This file contains implementation of EXTENT lock type
  44  *
  45  * EXTENT lock type is for locking a contiguous range of values, represented
  46  * by 64-bit starting and ending offsets (inclusive). There are several extent
  47  * lock modes, some of which may be mutually incompatible. Extent locks are
  48  * considered incompatible if their modes are incompatible and their extents
  49  * intersect.  See the lock mode compatibility matrix in lustre_dlm.h.
  50  */
  51
  52 #define DEBUG_SUBSYSTEM S_LDLM
  53 #include "../../include/linux/libcfs/libcfs.h"
  54 #include "../include/lustre_dlm.h"
  55 #include "../include/obd_support.h"
  56 #include "../include/obd.h"
  57 #include "../include/obd_class.h"
  58 #include "../include/lustre_lib.h"
  59 #include "ldlm_internal.h"
  60
  61
  62 /* When a lock is cancelled by a client, the KMS may undergo change if this
  63  * is the "highest lock".  This function returns the new KMS value.
  64  * Caller must hold lr_lock already.
  65  *
  66  * NB: A lock on [x,y] protects a KMS of up to y + 1 bytes! */
  67 __u64 ldlm_extent_shift_kms(struct ldlm_lock *lock, __u64 old_kms)
  68 {
  69         struct ldlm_resource *res = lock->l_resource;
  70         struct list_head *tmp;
  71         struct ldlm_lock *lck;
  72         __u64 kms = 0;
  73
  74         /* don't let another thread in ldlm_extent_shift_kms race in
  75          * just after we finish and take our lock into account in its
  76          * calculation of the kms */
  77         lock->l_flags |= LDLM_FL_KMS_IGNORE;
  78
  79         list_for_each(tmp, &res->lr_granted) {
  80                 lck = list_entry(tmp, struct ldlm_lock, l_res_link);
  81
  82                 if (lck->l_flags & LDLM_FL_KMS_IGNORE)
  83                         continue;
  84
  85                 if (lck->l_policy_data.l_extent.end >= old_kms)
  86                         return old_kms;
  87
  88                 /* This extent _has_ to be smaller than old_kms (checked above)
  89                  * so kms can only ever be smaller or the same as old_kms. */
  90                 if (lck->l_policy_data.l_extent.end + 1 > kms)
  91                         kms = lck->l_policy_data.l_extent.end + 1;
  92         }
  93         LASSERTF(kms <= old_kms, "kms %llu old_kms %llu\n", kms, old_kms);
  94
  95         return kms;
  96 }
  97 EXPORT_SYMBOL(ldlm_extent_shift_kms);
  98
  99 struct kmem_cache *ldlm_interval_slab;
 100 struct ldlm_interval *ldlm_interval_alloc(struct ldlm_lock *lock)
 101 {
 102         struct ldlm_interval *node;
 103
 104         LASSERT(lock->l_resource->lr_type == LDLM_EXTENT);
 105         OBD_SLAB_ALLOC_PTR_GFP(node, ldlm_interval_slab, GFP_NOFS);
 106         if (node == NULL)
 107                 return NULL;
 108
 109         INIT_LIST_HEAD(&node->li_group);
 110         ldlm_interval_attach(node, lock);
 111         return node;
 112 }
 113
 114 void ldlm_interval_free(struct ldlm_interval *node)
 115 {
 116         if (node) {
 117                 LASSERT(list_empty(&node->li_group));
 118                 LASSERT(!interval_is_intree(&node->li_node));
 119                 OBD_SLAB_FREE(node, ldlm_interval_slab, sizeof(*node));
 120         }
 121 }
 122
 123 /* interval tree, for LDLM_EXTENT. */
 124 void ldlm_interval_attach(struct ldlm_interval *n,
 125                           struct ldlm_lock *l)
 126 {
 127         LASSERT(l->l_tree_node == NULL);
 128         LASSERT(l->l_resource->lr_type == LDLM_EXTENT);
 129
 130         list_add_tail(&l->l_sl_policy, &n->li_group);
 131         l->l_tree_node = n;
 132 }
 133
 134 struct ldlm_interval *ldlm_interval_detach(struct ldlm_lock *l)
 135 {
 136         struct ldlm_interval *n = l->l_tree_node;
 137
 138         if (n == NULL)
 139                 return NULL;
 140
 141         LASSERT(!list_empty(&n->li_group));
 142         l->l_tree_node = NULL;
 143         list_del_init(&l->l_sl_policy);
 144
 145         return list_empty(&n->li_group) ? n : NULL;
 146 }
 147
 148 static inline int lock_mode_to_index(ldlm_mode_t mode)
 149 {
 150         int index;
 151
 152         LASSERT(mode != 0);
 153         LASSERT(IS_PO2(mode));
 154         for (index = -1; mode; index++, mode >>= 1) ;
 155         LASSERT(index < LCK_MODE_NUM);
 156         return index;
 157 }
 158
 159 /** Add newly granted lock into interval tree for the resource. */
 160 void ldlm_extent_add_lock(struct ldlm_resource *res,
 161                           struct ldlm_lock *lock)
 162 {
 163         struct interval_node *found, **root;
 164         struct ldlm_interval *node;
 165         struct ldlm_extent *extent;
 166         int idx;
 167
 168         LASSERT(lock->l_granted_mode == lock->l_req_mode);
 169
 170         node = lock->l_tree_node;
 171         LASSERT(node != NULL);
 172         LASSERT(!interval_is_intree(&node->li_node));
 173
 174         idx = lock_mode_to_index(lock->l_granted_mode);
 175         LASSERT(lock->l_granted_mode == 1 << idx);
 176         LASSERT(lock->l_granted_mode == res->lr_itree[idx].lit_mode);
 177
 178         /* node extent initialize */
 179         extent = &lock->l_policy_data.l_extent;
 180         interval_set(&node->li_node, extent->start, extent->end);
 181
 182         root = &res->lr_itree[idx].lit_root;
 183         found = interval_insert(&node->li_node, root);
 184         if (found) { /* The policy group found. */
 185                 struct ldlm_interval *tmp = ldlm_interval_detach(lock);
 186                 LASSERT(tmp != NULL);
 187                 ldlm_interval_free(tmp);
 188                 ldlm_interval_attach(to_ldlm_interval(found), lock);
 189         }
 190         res->lr_itree[idx].lit_size++;
 191
 192         /* even though we use interval tree to manage the extent lock, we also
 193          * add the locks into grant list, for debug purpose, .. */
 194         ldlm_resource_add_lock(res, &res->lr_granted, lock);
 195 }
 196
 197 /** Remove cancelled lock from resource interval tree. */
 198 void ldlm_extent_unlink_lock(struct ldlm_lock *lock)
 199 {
 200         struct ldlm_resource *res = lock->l_resource;
 201         struct ldlm_interval *node = lock->l_tree_node;
 202         struct ldlm_interval_tree *tree;
 203         int idx;
 204
 205         if (!node || !interval_is_intree(&node->li_node)) /* duplicate unlink */
 206                 return;
 207
 208         idx = lock_mode_to_index(lock->l_granted_mode);
 209         LASSERT(lock->l_granted_mode == 1 << idx);
 210         tree = &res->lr_itree[idx];
 211
 212         LASSERT(tree->lit_root != NULL); /* assure the tree is not null */
 213
 214         tree->lit_size--;
 215         node = ldlm_interval_detach(lock);
 216         if (node) {
 217                 interval_erase(&node->li_node, &tree->lit_root);
 218                 ldlm_interval_free(node);
 219         }
 220 }
 221
 222 void ldlm_extent_policy_wire_to_local(const ldlm_wire_policy_data_t *wpolicy,
 223                                      ldlm_policy_data_t *lpolicy)
 224 {
 225         memset(lpolicy, 0, sizeof(*lpolicy));
 226         lpolicy->l_extent.start = wpolicy->l_extent.start;
 227         lpolicy->l_extent.end = wpolicy->l_extent.end;
 228         lpolicy->l_extent.gid = wpolicy->l_extent.gid;
 229 }
 230
 231 void ldlm_extent_policy_local_to_wire(const ldlm_policy_data_t *lpolicy,
 232                                      ldlm_wire_policy_data_t *wpolicy)
 233 {
 234         memset(wpolicy, 0, sizeof(*wpolicy));
 235         wpolicy->l_extent.start = lpolicy->l_extent.start;
 236         wpolicy->l_extent.end = lpolicy->l_extent.end;
 237         wpolicy->l_extent.gid = lpolicy->l_extent.gid;
 238 }