bsd/hfs/hfscommon/BTree/BTreeNodeReserve.c

   1 /*
   2  * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 #include "../headers/BTreesPrivate.h"
  31 #include "sys/malloc.h"
  32 #include <kern/locks.h>
  33
  34
  35 /*
  36  * B-tree Node Reserve
  37  *
  38  * BTReserveSpace
  39  * BTReleaseReserve
  40  * BTUpdateReserve
  41  * BTAvailableNodes
  42  *
  43  * Each kernel thread can have it's own reserve of b-tree
  44  * nodes. This reserve info is kept in a hash table.
  45  *
  46  * Don't forget to call BTReleaseReserve when you're finished
  47  * or you will leave stale node reserves in the hash.
  48  */
  49
  50
  51 /*
  52  * BE CAREFUL WHEN INCREASING THE SIZE OF THIS STRUCT!
  53  *
  54  * It must remain equal in size to the opaque cat_cookie_t
  55  * struct (in hfs_catalog.h).
  56  */
  57 struct nreserve {
  58         LIST_ENTRY(nreserve) nr_hash;  /* hash chain */
  59         int  nr_nodecnt;               /* count of nodes held in reserve */
  60         int  nr_newnodes;              /* nodes that were allocated */
  61         struct  vnode *nr_btvp;        /* b-tree file vnode */
  62         void  *nr_tag;                 /* unique tag (per thread) */
  63 };
  64
  65 #define NR_GET_TAG()    (current_thread())
  66
  67 #define NR_CACHE 17
  68
  69 #define NR_HASH(btvp, tag) \
  70         (&nr_hashtbl[((((int)(btvp)) >> 8) ^ ((int)(tag) >> 4)) & nr_hashmask])
  71
  72 LIST_HEAD(nodereserve, nreserve) *nr_hashtbl;
  73
  74 u_long nr_hashmask;
  75
  76 lck_grp_t * nr_lck_grp;
  77 lck_grp_attr_t * nr_lck_grp_attr;
  78 lck_attr_t * nr_lck_attr;
  79
  80 lck_mtx_t  nr_mutex;
  81
  82 /* Internal Node Reserve Hash Routines (private) */
  83 static void nr_insert (struct vnode *, struct nreserve *nrp, int);
  84 static void nr_delete (struct vnode *, struct nreserve *nrp, int *);
  85 static int  nr_lookup (struct vnode *);
  86 static void nr_update (struct vnode *, int);
  87
  88
  89 /*
  90  * BTReserveSetup - initialize the node reserve hash table
  91  */
  92 __private_extern__
  93 void
  94 BTReserveSetup()
  95 {
  96         if (sizeof(struct nreserve) != sizeof(cat_cookie_t))
  97                 panic("BTReserveSetup: nreserve size != opaque struct size");
  98
  99         nr_hashtbl = hashinit(NR_CACHE, M_HFSMNT, &nr_hashmask);
 100
 101         nr_lck_grp_attr= lck_grp_attr_alloc_init();
 102         nr_lck_grp  = lck_grp_alloc_init("btree_node_reserve", nr_lck_grp_attr);
 103
 104         nr_lck_attr = lck_attr_alloc_init();
 105
 106         lck_mtx_init(&nr_mutex, nr_lck_grp, nr_lck_attr);
 107 }
 108
 109
 110 /*
 111  * BTAvailNodes - obtain the actual available nodes (for current thread)
 112  *
 113  */
 114 __private_extern__
 115 SInt32
 116 BTAvailableNodes(BTreeControlBlock *btree)
 117 {
 118         SInt32 availNodes;
 119
 120         availNodes = (SInt32)btree->freeNodes - (SInt32)btree->reservedNodes;
 121
 122         return (availNodes + nr_lookup(btree->fileRefNum));
 123 }
 124
 125
 126 /*
 127  * BTReserveSpace - obtain a node reserve (for current thread)
 128  *
 129  * Used by the Catalog Layer (hfs_catalog.c) to reserve space.
 130  */
 131 __private_extern__
 132 int
 133 BTReserveSpace(FCB *file, int operations, void* data)
 134 {
 135         BTreeControlBlock *btree;
 136         int rsrvNodes, availNodes, totalNodes;
 137         int height;
 138         int inserts, deletes;
 139         int err = 0;
 140
 141         btree = (BTreeControlBlockPtr)file->fcbBTCBPtr;
 142
 143         REQUIRE_FILE_LOCK(btree->fileRefNum, true);
 144
 145         /*
 146          * The node reserve is based on the number of b-tree
 147          * operations (insert/deletes) and the height of the
 148          * tree.
 149          */
 150         height = btree->treeDepth;
 151         inserts = operations & 0xffff;
 152         deletes = operations >> 16;
 153
 154         rsrvNodes = 1; /* allow for at least one root split */
 155         if (deletes)
 156                 rsrvNodes += (deletes * (height - 1)) - 1;
 157         if (inserts)
 158                 rsrvNodes += (inserts * height) + 1;
 159
 160         availNodes = btree->freeNodes - btree->reservedNodes;
 161
 162         if (rsrvNodes > availNodes) {
 163                 totalNodes = rsrvNodes + btree->totalNodes - availNodes;
 164
 165                 /* See if we also need a map node */
 166                 if (totalNodes > (int)CalcMapBits(btree))
 167                         ++totalNodes;
 168                 if ((err = ExtendBTree(btree, totalNodes)))
 169                         return (err);
 170         }
 171
 172         btree->reservedNodes += rsrvNodes;
 173         nr_insert(btree->fileRefNum, (struct nreserve *)data, rsrvNodes);
 174         return (0);
 175 }
 176
 177
 178 /*
 179  * BTReleaseReserve - release the node reserve held by current thread
 180  *
 181  * Used by the Catalog Layer (hfs_catalog.c) to relinquish reserved space.
 182  */
 183 __private_extern__
 184 int
 185 BTReleaseReserve(FCB *file, void* data)
 186 {
 187         BTreeControlBlock *btree;
 188         int nodecnt;
 189
 190         btree = (BTreeControlBlockPtr)file->fcbBTCBPtr;
 191
 192         REQUIRE_FILE_LOCK(btree->fileRefNum, true);
 193
 194         nr_delete(btree->fileRefNum, (struct nreserve *)data, &nodecnt);
 195
 196         if (nodecnt)
 197                 btree->reservedNodes -= nodecnt;
 198
 199         return (0);
 200 }
 201
 202 /*
 203  * BTUpdateReserve - update a node reserve for allocations that occurred.
 204  */
 205 __private_extern__
 206 void
 207 BTUpdateReserve(BTreeControlBlockPtr btreePtr, int nodes)
 208 {
 209         nr_update(btreePtr->fileRefNum, nodes);
 210 }
 211
 212
 213 /*----------------------------------------------------------------------------*/
 214 /* Node Reserve Hash Functions (private) */
 215
 216
 217 int nrinserts = 0;
 218 int nrdeletes = 0;
 219
 220 /*
 221  * Insert a new node reserve.
 222  */
 223 static void
 224 nr_insert(struct vnode * btvp, struct nreserve *nrp, int nodecnt)
 225 {
 226         struct nodereserve *nrhead;
 227         struct nreserve *tmp_nrp;
 228         void * tag = NR_GET_TAG();
 229
 230         /*
 231          * Check the cache - there may already be a reserve
 232          */
 233         lck_mtx_lock(&nr_mutex);
 234         nrhead = NR_HASH(btvp, tag);
 235         for (tmp_nrp = nrhead->lh_first; tmp_nrp;
 236              tmp_nrp = tmp_nrp->nr_hash.le_next) {
 237                 if ((tmp_nrp->nr_tag == tag) && (tmp_nrp->nr_btvp == btvp)) {
 238                         nrp->nr_tag = 0;
 239                         lck_mtx_unlock(&nr_mutex);
 240                         return;
 241                 }
 242         }
 243
 244         nrp->nr_nodecnt = nodecnt;
 245         nrp->nr_newnodes = 0;
 246         nrp->nr_btvp = btvp;
 247         nrp->nr_tag = tag;
 248         LIST_INSERT_HEAD(nrhead, nrp, nr_hash);
 249         ++nrinserts;
 250         lck_mtx_unlock(&nr_mutex);
 251 }
 252
 253 /*
 254  * Delete a node reserve.
 255  */
 256 static void
 257 nr_delete(struct vnode * btvp, struct nreserve *nrp, int *nodecnt)
 258 {
 259         void * tag = NR_GET_TAG();
 260
 261         lck_mtx_lock(&nr_mutex);
 262         if (nrp->nr_tag) {
 263                 if ((nrp->nr_tag != tag) || (nrp->nr_btvp != btvp))
 264                         panic("nr_delete: invalid NR (%08x)", nrp);
 265                 LIST_REMOVE(nrp, nr_hash);
 266                 *nodecnt = nrp->nr_nodecnt;
 267                 bzero(nrp, sizeof(struct nreserve));
 268                 ++nrdeletes;
 269         } else {
 270                 *nodecnt = 0;
 271         }
 272         lck_mtx_unlock(&nr_mutex);
 273 }
 274
 275 /*
 276  * Lookup a node reserve.
 277  */
 278 static int
 279 nr_lookup(struct vnode * btvp)
 280 {
 281         struct nodereserve *nrhead;
 282         struct nreserve *nrp;
 283         void* tag = NR_GET_TAG();
 284
 285         lck_mtx_lock(&nr_mutex);
 286
 287         nrhead = NR_HASH(btvp, tag);
 288         for (nrp = nrhead->lh_first; nrp; nrp = nrp->nr_hash.le_next) {
 289                 if ((nrp->nr_tag == tag) && (nrp->nr_btvp == btvp)) {
 290                         lck_mtx_unlock(&nr_mutex);
 291                         return (nrp->nr_nodecnt - nrp->nr_newnodes);
 292                 }
 293         }
 294         lck_mtx_unlock(&nr_mutex);
 295         return (0);
 296 }
 297
 298 /*
 299  * Update a node reserve for any allocations that occurred.
 300  */
 301 static void
 302 nr_update(struct vnode * btvp, int nodecnt)
 303 {
 304         struct nodereserve *nrhead;
 305         struct nreserve *nrp;
 306         void* tag = NR_GET_TAG();
 307
 308         lck_mtx_lock(&nr_mutex);
 309
 310         nrhead = NR_HASH(btvp, tag);
 311         for (nrp = nrhead->lh_first; nrp; nrp = nrp->nr_hash.le_next) {
 312                 if ((nrp->nr_tag == tag) && (nrp->nr_btvp == btvp)) {
 313                         nrp->nr_newnodes += nodecnt;
 314                         break;
 315                 }
 316         }
 317         lck_mtx_unlock(&nr_mutex);
 318 }