bsd/hfs/hfs_chash.c

   1 /*
   2  * Copyright (c) 2002-2005 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_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. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 /*
  30  * Copyright (c) 1982, 1986, 1989, 1991, 1993, 1995
  31  *      The Regents of the University of California.  All rights reserved.
  32  *
  33  * Redistribution and use in source and binary forms, with or without
  34  * modification, are permitted provided that the following conditions
  35  * are met:
  36  * 1. Redistributions of source code must retain the above copyright
  37  *        notice, this list of conditions and the following disclaimer.
  38  * 2. Redistributions in binary form must reproduce the above copyright
  39  *        notice, this list of conditions and the following disclaimer in the
  40  *        documentation and/or other materials provided with the distribution.
  41  * 3. All advertising materials mentioning features or use of this software
  42  *        must display the following acknowledgement:
  43  *      This product includes software developed by the University of
  44  *      California, Berkeley and its contributors.
  45  * 4. Neither the name of the University nor the names of its contributors
  46  *        may be used to endorse or promote products derived from this software
  47  *        without specific prior written permission.
  48  *
  49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  52  * ARE DISCLAIMED.      IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  59  * SUCH DAMAGE.
  60  *
  61  *      @(#)hfs_chash.c
  62  *      derived from @(#)ufs_ihash.c    8.7 (Berkeley) 5/17/95
  63  */
  64
  65 #include <sys/param.h>
  66 #include <sys/systm.h>
  67 #include <sys/vnode.h>
  68 #include <sys/kernel.h>
  69 #include <sys/malloc.h>
  70 #include <sys/proc.h>
  71 #include <sys/queue.h>
  72
  73
  74 #include "hfs.h"        /* XXX bringup */
  75 #include "hfs_cnode.h"
  76
  77 extern lck_attr_t *  hfs_lock_attr;
  78 extern lck_grp_t *  hfs_mutex_group;
  79 extern lck_grp_t *  hfs_rwlock_group;
  80
  81 lck_grp_t * chash_lck_grp;
  82 lck_grp_attr_t * chash_lck_grp_attr;
  83 lck_attr_t * chash_lck_attr;
  84
  85 /*
  86  * Structures associated with cnode caching.
  87  */
  88 LIST_HEAD(cnodehashhead, cnode) *cnodehashtbl;
  89 u_long  cnodehash;              /* size of hash table - 1 */
  90 #define CNODEHASH(device, inum) (&cnodehashtbl[((device) + (inum)) & cnodehash])
  91
  92 lck_mtx_t  hfs_chash_mutex;
  93
  94
  95 /*
  96  * Initialize cnode hash table.
  97  */
  98 __private_extern__
  99 void
 100 hfs_chashinit()
 101 {
 102         cnodehashtbl = hashinit(desiredvnodes, M_HFSMNT, &cnodehash);
 103
 104         chash_lck_grp_attr= lck_grp_attr_alloc_init();
 105         chash_lck_grp  = lck_grp_alloc_init("cnode_hash", chash_lck_grp_attr);
 106         chash_lck_attr = lck_attr_alloc_init();
 107
 108         lck_mtx_init(&hfs_chash_mutex, chash_lck_grp, chash_lck_attr);
 109 }
 110
 111
 112 /*
 113  * Use the device, inum pair to find the incore cnode.
 114  *
 115  * If it is in core, but locked, wait for it.
 116  */
 117 __private_extern__
 118 struct vnode *
 119 hfs_chash_getvnode(dev_t dev, ino_t inum, int wantrsrc, int skiplock)
 120 {
 121         struct cnode *cp;
 122         struct vnode *vp;
 123         int error;
 124         uint32_t vid;
 125
 126         /*
 127          * Go through the hash list
 128          * If a cnode is in the process of being cleaned out or being
 129          * allocated, wait for it to be finished and then try again.
 130          */
 131 loop:
 132         lck_mtx_lock(&hfs_chash_mutex);
 133         for (cp = CNODEHASH(dev, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 134                 if ((cp->c_fileid != inum) || (cp->c_dev != dev))
 135                         continue;
 136                 /* Wait if cnode is being created or reclaimed. */
 137                 if (ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 138                         SET(cp->c_hflag, H_WAITING);
 139
 140                         (void) msleep(cp, &hfs_chash_mutex, PDROP | PINOD,
 141                                       "hfs_chash_getvnode", 0);
 142                         goto loop;
 143                 }
 144                 /*
 145                  * Skip cnodes that are not in the name space anymore
 146                  * note that this check is done outside of the proper
 147                  * lock to catch nodes already in this state... this
 148                  * state must be rechecked after we acquire the cnode lock
 149                  */
 150                 if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 151                         continue;
 152                 }
 153                 /* Obtain the desired vnode. */
 154                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 155                 if (vp == NULLVP)
 156                         goto exit;
 157
 158                 vid = vnode_vid(vp);
 159                 lck_mtx_unlock(&hfs_chash_mutex);
 160
 161                 if ((error = vnode_getwithvid(vp, vid))) {
 162                         /*
 163                          * If vnode is being reclaimed, or has
 164                          * already changed identity, no need to wait
 165                          */
 166                         return (NULL);
 167                 }
 168                 if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK) != 0) {
 169                         vnode_put(vp);
 170                         return (NULL);
 171                 }
 172
 173                 /*
 174                  * Skip cnodes that are not in the name space anymore
 175                  * we need to check again with the cnode lock held
 176                  * because we may have blocked acquiring the vnode ref
 177                  * or the lock on the cnode which would allow the node
 178                  * to be unlinked
 179                  */
 180                 if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 181                         if (!skiplock)
 182                                 hfs_unlock(cp);
 183                         vnode_put(vp);
 184
 185                         return (NULL);
 186                 }
 187                 return (vp);
 188         }
 189 exit:
 190         lck_mtx_unlock(&hfs_chash_mutex);
 191         return (NULL);
 192 }
 193
 194
 195 /*
 196  * Use the device, fileid pair to find the incore cnode.
 197  * If no cnode if found one is created
 198  *
 199  * If it is in core, but locked, wait for it.
 200  */
 201 __private_extern__
 202 int
 203 hfs_chash_snoop(dev_t dev, ino_t inum, int (*callout)(const struct cat_desc *,
 204                 const struct cat_attr *, void *), void * arg)
 205 {
 206         struct cnode *cp;
 207         int result = ENOENT;
 208
 209         /*
 210          * Go through the hash list
 211          * If a cnode is in the process of being cleaned out or being
 212          * allocated, wait for it to be finished and then try again.
 213          */
 214         lck_mtx_lock(&hfs_chash_mutex);
 215         for (cp = CNODEHASH(dev, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 216                 if ((cp->c_fileid != inum) || (cp->c_dev != dev))
 217                         continue;
 218                 /* Skip cnodes being created or reclaimed. */
 219                 if (!ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 220                         result = callout(&cp->c_desc, &cp->c_attr, arg);
 221                 }
 222                 break;
 223         }
 224         lck_mtx_unlock(&hfs_chash_mutex);
 225         return (result);
 226 }
 227
 228
 229 /*
 230  * Use the device, fileid pair to find the incore cnode.
 231  * If no cnode if found one is created
 232  *
 233  * If it is in core, but locked, wait for it.
 234  */
 235 __private_extern__
 236 struct cnode *
 237 hfs_chash_getcnode(dev_t dev, ino_t inum, struct vnode **vpp, int wantrsrc, int skiplock)
 238 {
 239         struct cnode    *cp;
 240         struct cnode    *ncp = NULL;
 241         vnode_t         vp;
 242         uint32_t        vid;
 243
 244         /*
 245          * Go through the hash list
 246          * If a cnode is in the process of being cleaned out or being
 247          * allocated, wait for it to be finished and then try again.
 248          */
 249 loop:
 250         lck_mtx_lock(&hfs_chash_mutex);
 251
 252 loop_with_lock:
 253         for (cp = CNODEHASH(dev, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 254                 if ((cp->c_fileid != inum) || (cp->c_dev != dev))
 255                         continue;
 256                 /*
 257                  * Wait if cnode is being created, attached to or reclaimed.
 258                  */
 259                 if (ISSET(cp->c_hflag, H_ALLOC | H_ATTACH | H_TRANSIT)) {
 260                         SET(cp->c_hflag, H_WAITING);
 261
 262                         (void) msleep(cp, &hfs_chash_mutex, PINOD,
 263                                       "hfs_chash_getcnode", 0);
 264                         goto loop_with_lock;
 265                 }
 266                 /*
 267                  * Skip cnodes that are not in the name space anymore
 268                  * note that this check is done outside of the proper
 269                  * lock to catch nodes already in this state... this
 270                  * state must be rechecked after we acquire the cnode lock
 271                  */
 272                 if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 273                         continue;
 274                 }
 275                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 276                 if (vp == NULL) {
 277                         /*
 278                          * The desired vnode isn't there so tag the cnode.
 279                          */
 280                         SET(cp->c_hflag, H_ATTACH);
 281
 282                         lck_mtx_unlock(&hfs_chash_mutex);
 283                 } else {
 284                         vid = vnode_vid(vp);
 285
 286                         lck_mtx_unlock(&hfs_chash_mutex);
 287
 288                         if (vnode_getwithvid(vp, vid))
 289                                 goto loop;
 290                 }
 291                 if (ncp) {
 292                         /*
 293                          * someone else won the race to create
 294                          * this cnode and add it to the hash
 295                          * just dump our allocation
 296                          */
 297                         FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
 298                         ncp = NULL;
 299                 }
 300                 if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK) != 0) {
 301                         if (vp != NULLVP)
 302                                 vnode_put(vp);
 303                         lck_mtx_lock(&hfs_chash_mutex);
 304
 305                         if (vp == NULLVP)
 306                                 CLR(cp->c_hflag, H_ATTACH);
 307                         goto loop_with_lock;
 308                 }
 309                 /*
 310                  * Skip cnodes that are not in the name space anymore
 311                  * we need to check again with the cnode lock held
 312                  * because we may have blocked acquiring the vnode ref
 313                  * or the lock on the cnode which would allow the node
 314                  * to be unlinked
 315                  */
 316                 if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 317                         if (!skiplock)
 318                                 hfs_unlock(cp);
 319                         if (vp != NULLVP)
 320                                 vnode_put(vp);
 321                         lck_mtx_lock(&hfs_chash_mutex);
 322
 323                         if (vp == NULLVP)
 324                                 CLR(cp->c_hflag, H_ATTACH);
 325                         goto loop_with_lock;
 326                 }
 327                 *vpp = vp;
 328                 return (cp);
 329         }
 330
 331         /*
 332          * Allocate a new cnode
 333          */
 334         if (skiplock)
 335                 panic("%s - should never get here when skiplock is set \n", __FUNCTION__);
 336
 337         if (ncp == NULL) {
 338                 lck_mtx_unlock(&hfs_chash_mutex);
 339
 340                 MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
 341                 /*
 342                  * since we dropped the chash lock,
 343                  * we need to go back and re-verify
 344                  * that this node hasn't come into
 345                  * existence...
 346                  */
 347                 goto loop;
 348         }
 349         bzero(ncp, sizeof(struct cnode));
 350         SET(ncp->c_hflag, H_ALLOC);
 351         ncp->c_fileid = inum;
 352         ncp->c_dev = dev;
 353         TAILQ_INIT(&ncp->c_hintlist); /* make the list empty */
 354
 355         lck_rw_init(&ncp->c_rwlock, hfs_rwlock_group, hfs_lock_attr);
 356         if (!skiplock)
 357                 (void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK);
 358
 359         /* Insert the new cnode with it's H_ALLOC flag set */
 360         LIST_INSERT_HEAD(CNODEHASH(dev, inum), ncp, c_hash);
 361         lck_mtx_unlock(&hfs_chash_mutex);
 362
 363         *vpp = NULL;
 364         return (ncp);
 365 }
 366
 367
 368 __private_extern__
 369 void
 370 hfs_chashwakeup(struct cnode *cp, int hflags)
 371 {
 372         lck_mtx_lock(&hfs_chash_mutex);
 373
 374         CLR(cp->c_hflag, hflags);
 375
 376         if (ISSET(cp->c_hflag, H_WAITING)) {
 377                 CLR(cp->c_hflag, H_WAITING);
 378                 wakeup((caddr_t)cp);
 379         }
 380         lck_mtx_unlock(&hfs_chash_mutex);
 381 }
 382
 383
 384 /*
 385  * Re-hash two cnodes in the hash table.
 386  */
 387 __private_extern__
 388 void
 389 hfs_chash_rehash(struct cnode *cp1, struct cnode *cp2)
 390 {
 391         lck_mtx_lock(&hfs_chash_mutex);
 392
 393         LIST_REMOVE(cp1, c_hash);
 394         LIST_REMOVE(cp2, c_hash);
 395         LIST_INSERT_HEAD(CNODEHASH(cp1->c_dev, cp1->c_fileid), cp1, c_hash);
 396         LIST_INSERT_HEAD(CNODEHASH(cp2->c_dev, cp2->c_fileid), cp2, c_hash);
 397
 398         lck_mtx_unlock(&hfs_chash_mutex);
 399 }
 400
 401
 402 /*
 403  * Remove a cnode from the hash table.
 404  */
 405 __private_extern__
 406 int
 407 hfs_chashremove(struct cnode *cp)
 408 {
 409         lck_mtx_lock(&hfs_chash_mutex);
 410
 411         /* Check if a vnode is getting attached */
 412         if (ISSET(cp->c_hflag, H_ATTACH)) {
 413                 lck_mtx_unlock(&hfs_chash_mutex);
 414                 return (EBUSY);
 415         }
 416         LIST_REMOVE(cp, c_hash);
 417         cp->c_hash.le_next = NULL;
 418         cp->c_hash.le_prev = NULL;
 419
 420         lck_mtx_unlock(&hfs_chash_mutex);
 421         return (0);
 422 }
 423
 424 /*
 425  * Remove a cnode from the hash table and wakeup any waiters.
 426  */
 427 __private_extern__
 428 void
 429 hfs_chash_abort(struct cnode *cp)
 430 {
 431         lck_mtx_lock(&hfs_chash_mutex);
 432
 433         LIST_REMOVE(cp, c_hash);
 434         cp->c_hash.le_next = NULL;
 435         cp->c_hash.le_prev = NULL;
 436
 437         CLR(cp->c_hflag, H_ATTACH | H_ALLOC);
 438         if (ISSET(cp->c_hflag, H_WAITING)) {
 439                 CLR(cp->c_hflag, H_WAITING);
 440                 wakeup((caddr_t)cp);
 441         }
 442         lck_mtx_unlock(&hfs_chash_mutex);
 443 }
 444
 445
 446 /*
 447  * mark a cnode as in transistion
 448  */
 449 __private_extern__
 450 void
 451 hfs_chash_mark_in_transit(struct cnode *cp)
 452 {
 453         lck_mtx_lock(&hfs_chash_mutex);
 454
 455         SET(cp->c_hflag, H_TRANSIT);
 456
 457         lck_mtx_unlock(&hfs_chash_mutex);
 458 }