bsd/hfs/hfs_chash.c

   1 /*
   2  * Copyright (c) 2002-2012 Apple 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 #define CNODEHASH(hfsmp, inum) (&hfsmp->hfs_cnodehashtbl[(inum) & hfsmp->hfs_cnodehash])
  87
  88
  89 /*
  90  * Initialize cnode hash table.
  91  */
  92 __private_extern__
  93 void
  94 hfs_chashinit()
  95 {
  96         chash_lck_grp_attr= lck_grp_attr_alloc_init();
  97         chash_lck_grp  = lck_grp_alloc_init("cnode_hash", chash_lck_grp_attr);
  98         chash_lck_attr = lck_attr_alloc_init();
  99 }
 100
 101 static void hfs_chash_lock(struct hfsmount *hfsmp)
 102 {
 103         lck_mtx_lock(&hfsmp->hfs_chash_mutex);
 104 }
 105
 106 static void hfs_chash_lock_spin(struct hfsmount *hfsmp)
 107 {
 108         lck_mtx_lock_spin(&hfsmp->hfs_chash_mutex);
 109 }
 110
 111 static void hfs_chash_lock_convert (__unused struct hfsmount *hfsmp)
 112 {
 113         lck_mtx_convert_spin(&hfsmp->hfs_chash_mutex);
 114 }
 115
 116 static void hfs_chash_unlock(struct hfsmount *hfsmp)
 117 {
 118         lck_mtx_unlock(&hfsmp->hfs_chash_mutex);
 119 }
 120
 121 __private_extern__
 122 void
 123 hfs_chashinit_finish(struct hfsmount *hfsmp)
 124 {
 125         lck_mtx_init(&hfsmp->hfs_chash_mutex, chash_lck_grp, chash_lck_attr);
 126
 127         hfsmp->hfs_cnodehashtbl = hashinit(desiredvnodes / 4, M_HFSMNT, &hfsmp->hfs_cnodehash);
 128 }
 129
 130 __private_extern__
 131 void
 132 hfs_delete_chash(struct hfsmount *hfsmp)
 133 {
 134         lck_mtx_destroy(&hfsmp->hfs_chash_mutex, chash_lck_grp);
 135
 136         FREE(hfsmp->hfs_cnodehashtbl, M_HFSMNT);
 137 }
 138
 139
 140 /*
 141  * Use the device, inum pair to find the incore cnode.
 142  *
 143  * If it is in core, but locked, wait for it.
 144  */
 145 struct vnode *
 146 hfs_chash_getvnode(struct hfsmount *hfsmp, ino_t inum, int wantrsrc, int skiplock, int allow_deleted)
 147 {
 148         struct cnode *cp;
 149         struct vnode *vp;
 150         int error;
 151         u_int32_t vid;
 152
 153         /*
 154          * Go through the hash list
 155          * If a cnode is in the process of being cleaned out or being
 156          * allocated, wait for it to be finished and then try again.
 157          */
 158 loop:
 159         hfs_chash_lock_spin(hfsmp);
 160
 161         for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 162                 if (cp->c_fileid != inum)
 163                         continue;
 164                 /* Wait if cnode is being created or reclaimed. */
 165                 if (ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 166                         SET(cp->c_hflag, H_WAITING);
 167
 168                         (void) msleep(cp, &hfsmp->hfs_chash_mutex, PDROP | PINOD,
 169                                       "hfs_chash_getvnode", 0);
 170                         goto loop;
 171                 }
 172                 /* Obtain the desired vnode. */
 173                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 174                 if (vp == NULLVP)
 175                         goto exit;
 176
 177                 vid = vnode_vid(vp);
 178                 hfs_chash_unlock(hfsmp);
 179
 180                 if ((error = vnode_getwithvid(vp, vid))) {
 181                         /*
 182                          * If vnode is being reclaimed, or has
 183                          * already changed identity, no need to wait
 184                          */
 185                         return (NULL);
 186                 }
 187                 if (!skiplock && hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT) != 0) {
 188                         vnode_put(vp);
 189                         return (NULL);
 190                 }
 191
 192                 /*
 193                  * Skip cnodes that are not in the name space anymore
 194                  * we need to check with the cnode lock held because
 195                  * we may have blocked acquiring the vnode ref or the
 196                  * lock on the cnode which would allow the node to be
 197                  * unlinked
 198                  */
 199                 if (!allow_deleted) {
 200                         if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 201                                 if (!skiplock) {
 202                                         hfs_unlock(cp);
 203                                 }
 204                                 vnode_put(vp);
 205                                 return (NULL);
 206                         }
 207                 }
 208                 return (vp);
 209         }
 210 exit:
 211         hfs_chash_unlock(hfsmp);
 212         return (NULL);
 213 }
 214
 215
 216 /*
 217  * Use the device, fileid pair to snoop an incore cnode.
 218  *
 219  * A cnode can exists in chash even after it has been
 220  * deleted from the catalog, so this function returns
 221  * ENOENT if C_NOEXIST is set in the cnode's flag.
 222  *
 223  */
 224 int
 225 hfs_chash_snoop(struct hfsmount *hfsmp, ino_t inum, int existence_only, int (*callout)(const struct cat_desc *,
 226                 const struct cat_attr *, void *), void * arg)
 227 {
 228         struct cnode *cp;
 229         int result = ENOENT;
 230
 231         /*
 232          * Go through the hash list
 233          * If a cnode is in the process of being cleaned out or being
 234          * allocated, wait for it to be finished and then try again.
 235          */
 236         hfs_chash_lock(hfsmp);
 237
 238         for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 239                 if (cp->c_fileid != inum)
 240                         continue;
 241
 242                 /*
 243                  * Under normal circumstances, we would want to return ENOENT if a cnode is in
 244                  * the hash and it is marked C_NOEXISTS or C_DELETED.  However, if the CNID
 245                  * namespace has wrapped around, then we have the possibility of collisions.
 246                  * In that case, we may use this function to validate whether or not we
 247                  * should trust the nextCNID value in the hfs mount point.
 248                  *
 249                  * If we didn't do this, then it would be possible for a cnode that is no longer backed
 250                  * by anything on-disk (C_NOEXISTS) to still exist in the hash along with its
 251                  * vnode.  The cat_create routine could then create a new entry in the catalog
 252                  * re-using that CNID.  Then subsequent hfs_getnewvnode calls will repeatedly fail
 253                  * trying to look it up/validate it because it is marked C_NOEXISTS.  So we want
 254                  * to prevent that from happening as much as possible.
 255                  */
 256                 if (existence_only) {
 257                         result = 0;
 258                         break;
 259                 }
 260
 261                 /* Skip cnodes that have been removed from the catalog */
 262                 if (cp->c_flag & (C_NOEXISTS | C_DELETED)) {
 263                         break;
 264                 }
 265                 /* Skip cnodes being created or reclaimed. */
 266                 if (!ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 267                         result = callout(&cp->c_desc, &cp->c_attr, arg);
 268                 }
 269                 break;
 270         }
 271         hfs_chash_unlock(hfsmp);
 272
 273         return (result);
 274 }
 275
 276
 277 /*
 278  * Use the device, fileid pair to find the incore cnode.
 279  * If no cnode if found one is created
 280  *
 281  * If it is in core, but locked, wait for it.
 282  *
 283  * If the cnode is C_DELETED, then return NULL since that
 284  * inum is no longer valid for lookups (open-unlinked file).
 285  *
 286  * If the cnode is C_DELETED but also marked C_RENAMED, then that means
 287  * the cnode was renamed over and a new entry exists in its place.  The caller
 288  * should re-drive the lookup to get the newer entry.  In that case, we'll still
 289  * return NULL for the cnode, but also return GNV_CHASH_RENAMED in the output flags
 290  * of this function to indicate the caller that they should re-drive.
 291  */
 292 struct cnode *
 293 hfs_chash_getcnode(struct hfsmount *hfsmp, ino_t inum, struct vnode **vpp,
 294                                    int wantrsrc, int skiplock, int *out_flags, int *hflags)
 295 {
 296         struct cnode    *cp;
 297         struct cnode    *ncp = NULL;
 298         vnode_t         vp;
 299         u_int32_t       vid;
 300
 301         /*
 302          * Go through the hash list
 303          * If a cnode is in the process of being cleaned out or being
 304          * allocated, wait for it to be finished and then try again.
 305          */
 306 loop:
 307         hfs_chash_lock_spin(hfsmp);
 308
 309 loop_with_lock:
 310         for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 311                 if (cp->c_fileid != inum)
 312                         continue;
 313                 /*
 314                  * Wait if cnode is being created, attached to or reclaimed.
 315                  */
 316                 if (ISSET(cp->c_hflag, H_ALLOC | H_ATTACH | H_TRANSIT)) {
 317                         SET(cp->c_hflag, H_WAITING);
 318
 319                         (void) msleep(cp, &hfsmp->hfs_chash_mutex, PINOD,
 320                                       "hfs_chash_getcnode", 0);
 321                         goto loop_with_lock;
 322                 }
 323                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 324                 if (vp == NULL) {
 325                         /*
 326                          * The desired vnode isn't there so tag the cnode.
 327                          */
 328                         SET(cp->c_hflag, H_ATTACH);
 329                         *hflags |= H_ATTACH;
 330
 331                         hfs_chash_unlock(hfsmp);
 332                 } else {
 333                         vid = vnode_vid(vp);
 334
 335                         hfs_chash_unlock(hfsmp);
 336
 337                         if (vnode_getwithvid(vp, vid))
 338                                 goto loop;
 339                 }
 340                 if (ncp) {
 341                         /*
 342                          * someone else won the race to create
 343                          * this cnode and add it to the hash
 344                          * just dump our allocation
 345                          */
 346                         FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
 347                         ncp = NULL;
 348                 }
 349
 350                 if (!skiplock) {
 351                         hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_ALLOW_NOEXISTS);
 352                 }
 353
 354                 /*
 355                  * Skip cnodes that are not in the name space anymore
 356                  * we need to check with the cnode lock held because
 357                  * we may have blocked acquiring the vnode ref or the
 358                  * lock on the cnode which would allow the node to be
 359                  * unlinked.
 360                  *
 361                  * Don't return a cnode in this case since the inum
 362                  * is no longer valid for lookups.
 363                  */
 364                 if ((cp->c_flag & (C_NOEXISTS | C_DELETED)) && !wantrsrc) {
 365                         int renamed = 0;
 366                         if (cp->c_flag & C_RENAMED) {
 367                                 renamed = 1;
 368                         }
 369                         if (!skiplock)
 370                                 hfs_unlock(cp);
 371                         if (vp != NULLVP) {
 372                                 vnode_put(vp);
 373                         } else {
 374                                 hfs_chash_lock_spin(hfsmp);
 375                                 CLR(cp->c_hflag, H_ATTACH);
 376                                 *hflags &= ~H_ATTACH;
 377                                 if (ISSET(cp->c_hflag, H_WAITING)) {
 378                                         CLR(cp->c_hflag, H_WAITING);
 379                                         wakeup((caddr_t)cp);
 380                                 }
 381                                 hfs_chash_unlock(hfsmp);
 382                         }
 383                         vp = NULL;
 384                         cp = NULL;
 385                         if (renamed) {
 386                                 *out_flags = GNV_CHASH_RENAMED;
 387                         }
 388                 }
 389                 *vpp = vp;
 390                 return (cp);
 391         }
 392
 393         /*
 394          * Allocate a new cnode
 395          */
 396         if (skiplock && !wantrsrc)
 397                 panic("%s - should never get here when skiplock is set \n", __FUNCTION__);
 398
 399         if (ncp == NULL) {
 400                 hfs_chash_unlock(hfsmp);
 401
 402                 MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
 403                 /*
 404                  * since we dropped the chash lock,
 405                  * we need to go back and re-verify
 406                  * that this node hasn't come into
 407                  * existence...
 408                  */
 409                 goto loop;
 410         }
 411         hfs_chash_lock_convert(hfsmp);
 412
 413         bzero(ncp, sizeof(struct cnode));
 414         SET(ncp->c_hflag, H_ALLOC);
 415         *hflags |= H_ALLOC;
 416         ncp->c_fileid = inum;
 417         TAILQ_INIT(&ncp->c_hintlist); /* make the list empty */
 418         TAILQ_INIT(&ncp->c_originlist);
 419
 420         lck_rw_init(&ncp->c_rwlock, hfs_rwlock_group, hfs_lock_attr);
 421         if (!skiplock)
 422                 (void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT);
 423
 424         /* Insert the new cnode with it's H_ALLOC flag set */
 425         LIST_INSERT_HEAD(CNODEHASH(hfsmp, inum), ncp, c_hash);
 426         hfs_chash_unlock(hfsmp);
 427
 428         *vpp = NULL;
 429         return (ncp);
 430 }
 431
 432
 433 __private_extern__
 434 void
 435 hfs_chashwakeup(struct hfsmount *hfsmp, struct cnode *cp, int hflags)
 436 {
 437         hfs_chash_lock_spin(hfsmp);
 438
 439         CLR(cp->c_hflag, hflags);
 440
 441         if (ISSET(cp->c_hflag, H_WAITING)) {
 442                 CLR(cp->c_hflag, H_WAITING);
 443                 wakeup((caddr_t)cp);
 444         }
 445         hfs_chash_unlock(hfsmp);
 446 }
 447
 448
 449 /*
 450  * Re-hash two cnodes in the hash table.
 451  */
 452 __private_extern__
 453 void
 454 hfs_chash_rehash(struct hfsmount *hfsmp, struct cnode *cp1, struct cnode *cp2)
 455 {
 456         hfs_chash_lock_spin(hfsmp);
 457
 458         LIST_REMOVE(cp1, c_hash);
 459         LIST_REMOVE(cp2, c_hash);
 460         LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp1->c_fileid), cp1, c_hash);
 461         LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp2->c_fileid), cp2, c_hash);
 462
 463         hfs_chash_unlock(hfsmp);
 464 }
 465
 466
 467 /*
 468  * Remove a cnode from the hash table.
 469  */
 470 __private_extern__
 471 int
 472 hfs_chashremove(struct hfsmount *hfsmp, struct cnode *cp)
 473 {
 474         hfs_chash_lock_spin(hfsmp);
 475
 476         /* Check if a vnode is getting attached */
 477         if (ISSET(cp->c_hflag, H_ATTACH)) {
 478                 hfs_chash_unlock(hfsmp);
 479                 return (EBUSY);
 480         }
 481         if (cp->c_hash.le_next || cp->c_hash.le_prev) {
 482             LIST_REMOVE(cp, c_hash);
 483             cp->c_hash.le_next = NULL;
 484             cp->c_hash.le_prev = NULL;
 485         }
 486         hfs_chash_unlock(hfsmp);
 487
 488         return (0);
 489 }
 490
 491 /*
 492  * Remove a cnode from the hash table and wakeup any waiters.
 493  */
 494 __private_extern__
 495 void
 496 hfs_chash_abort(struct hfsmount *hfsmp, struct cnode *cp)
 497 {
 498         hfs_chash_lock_spin(hfsmp);
 499
 500         LIST_REMOVE(cp, c_hash);
 501         cp->c_hash.le_next = NULL;
 502         cp->c_hash.le_prev = NULL;
 503
 504         CLR(cp->c_hflag, H_ATTACH | H_ALLOC);
 505         if (ISSET(cp->c_hflag, H_WAITING)) {
 506                 CLR(cp->c_hflag, H_WAITING);
 507                 wakeup((caddr_t)cp);
 508         }
 509         hfs_chash_unlock(hfsmp);
 510 }
 511
 512
 513 /*
 514  * mark a cnode as in transition
 515  */
 516 __private_extern__
 517 void
 518 hfs_chash_mark_in_transit(struct hfsmount *hfsmp, struct cnode *cp)
 519 {
 520         hfs_chash_lock_spin(hfsmp);
 521
 522         SET(cp->c_hflag, H_TRANSIT);
 523
 524         hfs_chash_unlock(hfsmp);
 525 }
 526
 527 /* Search a cnode in the hash.  This function does not return cnode which
 528  * are getting created, destroyed or in transition.  Note that this function
 529  * does not acquire the cnode hash mutex, and expects the caller to acquire it.
 530  * On success, returns pointer to the cnode found.  On failure, returns NULL.
 531  */
 532 static
 533 struct cnode *
 534 hfs_chash_search_cnid(struct hfsmount *hfsmp, cnid_t cnid)
 535 {
 536         struct cnode *cp;
 537
 538         for (cp = CNODEHASH(hfsmp, cnid)->lh_first; cp; cp = cp->c_hash.le_next) {
 539                 if (cp->c_fileid == cnid) {
 540                         break;
 541                 }
 542         }
 543
 544         /* If cnode is being created or reclaimed, return error. */
 545         if (cp && ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 546                 cp = NULL;
 547         }
 548
 549         return cp;
 550 }
 551
 552 /* Search a cnode corresponding to given device and ID in the hash.  If the
 553  * found cnode has kHFSHasChildLinkBit cleared, set it.  If the cnode is not
 554  * found, no new cnode is created and error is returned.
 555  *
 556  * Return values -
 557  *      -1 : The cnode was not found.
 558  *       0 : The cnode was found, and the kHFSHasChildLinkBit was already set.
 559  *       1 : The cnode was found, the kHFSHasChildLinkBit was not set, and the
 560  *           function had to set that bit.
 561  */
 562 __private_extern__
 563 int
 564 hfs_chash_set_childlinkbit(struct hfsmount *hfsmp, cnid_t cnid)
 565 {
 566         int retval = -1;
 567         struct cnode *cp;
 568
 569         hfs_chash_lock_spin(hfsmp);
 570
 571         cp = hfs_chash_search_cnid(hfsmp, cnid);
 572         if (cp) {
 573                 if (cp->c_attr.ca_recflags & kHFSHasChildLinkMask) {
 574                         retval = 0;
 575                 } else {
 576                         cp->c_attr.ca_recflags |= kHFSHasChildLinkMask;
 577                         retval = 1;
 578                 }
 579         }
 580         hfs_chash_unlock(hfsmp);
 581
 582         return retval;
 583 }