bsd/hfs/hfscommon/BTree/BTreeNodeReserve.c

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