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,
 226                                 int (*callout)(const cnode_t *cp, 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                         result = EACCES;
 264                         break;
 265                 }
 266
 267                 /* Skip cnodes being created or reclaimed. */
 268                 if (!ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 269                         result = callout(cp, arg);
 270                 }
 271                 break;
 272         }
 273         hfs_chash_unlock(hfsmp);
 274
 275         return (result);
 276 }
 277
 278
 279 /*
 280  * Use the device, fileid pair to find the incore cnode.
 281  * If no cnode if found one is created
 282  *
 283  * If it is in core, but locked, wait for it.
 284  *
 285  * If the cnode is C_DELETED, then return NULL since that
 286  * inum is no longer valid for lookups (open-unlinked file).
 287  *
 288  * If the cnode is C_DELETED but also marked C_RENAMED, then that means
 289  * the cnode was renamed over and a new entry exists in its place.  The caller
 290  * should re-drive the lookup to get the newer entry.  In that case, we'll still
 291  * return NULL for the cnode, but also return GNV_CHASH_RENAMED in the output flags
 292  * of this function to indicate the caller that they should re-drive.
 293  */
 294 struct cnode *
 295 hfs_chash_getcnode(struct hfsmount *hfsmp, ino_t inum, struct vnode **vpp,
 296                                    int wantrsrc, int skiplock, int *out_flags, int *hflags)
 297 {
 298         struct cnode    *cp;
 299         struct cnode    *ncp = NULL;
 300         vnode_t         vp;
 301         u_int32_t       vid;
 302
 303         /*
 304          * Go through the hash list
 305          * If a cnode is in the process of being cleaned out or being
 306          * allocated, wait for it to be finished and then try again.
 307          */
 308 loop:
 309         hfs_chash_lock_spin(hfsmp);
 310
 311 loop_with_lock:
 312         for (cp = CNODEHASH(hfsmp, inum)->lh_first; cp; cp = cp->c_hash.le_next) {
 313                 if (cp->c_fileid != inum)
 314                         continue;
 315                 /*
 316                  * Wait if cnode is being created, attached to or reclaimed.
 317                  */
 318                 if (ISSET(cp->c_hflag, H_ALLOC | H_ATTACH | H_TRANSIT)) {
 319                         SET(cp->c_hflag, H_WAITING);
 320
 321                         (void) msleep(cp, &hfsmp->hfs_chash_mutex, PINOD,
 322                                       "hfs_chash_getcnode", 0);
 323                         goto loop_with_lock;
 324                 }
 325                 vp = wantrsrc ? cp->c_rsrc_vp : cp->c_vp;
 326                 if (vp == NULL) {
 327                         /*
 328                          * The desired vnode isn't there so tag the cnode.
 329                          */
 330                         SET(cp->c_hflag, H_ATTACH);
 331                         *hflags |= H_ATTACH;
 332
 333                         hfs_chash_unlock(hfsmp);
 334                 } else {
 335                         vid = vnode_vid(vp);
 336
 337                         hfs_chash_unlock(hfsmp);
 338
 339                         if (vnode_getwithvid(vp, vid))
 340                                 goto loop;
 341                 }
 342                 if (ncp) {
 343                         /*
 344                          * someone else won the race to create
 345                          * this cnode and add it to the hash
 346                          * just dump our allocation
 347                          */
 348                         FREE_ZONE(ncp, sizeof(struct cnode), M_HFSNODE);
 349                         ncp = NULL;
 350                 }
 351
 352                 if (!skiplock) {
 353                         hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_ALLOW_NOEXISTS);
 354                 }
 355
 356                 /*
 357                  * Skip cnodes that are not in the name space anymore
 358                  * we need to check with the cnode lock held because
 359                  * we may have blocked acquiring the vnode ref or the
 360                  * lock on the cnode which would allow the node to be
 361                  * unlinked.
 362                  *
 363                  * Don't return a cnode in this case since the inum
 364                  * is no longer valid for lookups.
 365                  */
 366                 if ((cp->c_flag & (C_NOEXISTS | C_DELETED)) && !wantrsrc) {
 367                         int renamed = 0;
 368                         if (cp->c_flag & C_RENAMED) {
 369                                 renamed = 1;
 370                         }
 371                         if (!skiplock)
 372                                 hfs_unlock(cp);
 373                         if (vp != NULLVP) {
 374                                 vnode_put(vp);
 375                         } else {
 376                                 hfs_chash_lock_spin(hfsmp);
 377                                 CLR(cp->c_hflag, H_ATTACH);
 378                                 *hflags &= ~H_ATTACH;
 379                                 if (ISSET(cp->c_hflag, H_WAITING)) {
 380                                         CLR(cp->c_hflag, H_WAITING);
 381                                         wakeup((caddr_t)cp);
 382                                 }
 383                                 hfs_chash_unlock(hfsmp);
 384                         }
 385                         vp = NULL;
 386                         cp = NULL;
 387                         if (renamed) {
 388                                 *out_flags = GNV_CHASH_RENAMED;
 389                         }
 390                 }
 391                 *vpp = vp;
 392                 return (cp);
 393         }
 394
 395         /*
 396          * Allocate a new cnode
 397          */
 398         if (skiplock && !wantrsrc)
 399                 panic("%s - should never get here when skiplock is set \n", __FUNCTION__);
 400
 401         if (ncp == NULL) {
 402                 hfs_chash_unlock(hfsmp);
 403
 404                 MALLOC_ZONE(ncp, struct cnode *, sizeof(struct cnode), M_HFSNODE, M_WAITOK);
 405                 /*
 406                  * since we dropped the chash lock,
 407                  * we need to go back and re-verify
 408                  * that this node hasn't come into
 409                  * existence...
 410                  */
 411                 goto loop;
 412         }
 413         hfs_chash_lock_convert(hfsmp);
 414
 415         bzero(ncp, sizeof(struct cnode));
 416         SET(ncp->c_hflag, H_ALLOC);
 417         *hflags |= H_ALLOC;
 418         ncp->c_fileid = inum;
 419         TAILQ_INIT(&ncp->c_hintlist); /* make the list empty */
 420         TAILQ_INIT(&ncp->c_originlist);
 421
 422         lck_rw_init(&ncp->c_rwlock, hfs_rwlock_group, hfs_lock_attr);
 423         if (!skiplock)
 424                 (void) hfs_lock(ncp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT);
 425
 426         /* Insert the new cnode with it's H_ALLOC flag set */
 427         LIST_INSERT_HEAD(CNODEHASH(hfsmp, inum), ncp, c_hash);
 428         hfs_chash_unlock(hfsmp);
 429
 430         *vpp = NULL;
 431         return (ncp);
 432 }
 433
 434
 435 __private_extern__
 436 void
 437 hfs_chashwakeup(struct hfsmount *hfsmp, struct cnode *cp, int hflags)
 438 {
 439         hfs_chash_lock_spin(hfsmp);
 440
 441         CLR(cp->c_hflag, hflags);
 442
 443         if (ISSET(cp->c_hflag, H_WAITING)) {
 444                 CLR(cp->c_hflag, H_WAITING);
 445                 wakeup((caddr_t)cp);
 446         }
 447         hfs_chash_unlock(hfsmp);
 448 }
 449
 450
 451 /*
 452  * Re-hash two cnodes in the hash table.
 453  */
 454 __private_extern__
 455 void
 456 hfs_chash_rehash(struct hfsmount *hfsmp, struct cnode *cp1, struct cnode *cp2)
 457 {
 458         hfs_chash_lock_spin(hfsmp);
 459
 460         LIST_REMOVE(cp1, c_hash);
 461         LIST_REMOVE(cp2, c_hash);
 462         LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp1->c_fileid), cp1, c_hash);
 463         LIST_INSERT_HEAD(CNODEHASH(hfsmp, cp2->c_fileid), cp2, c_hash);
 464
 465         hfs_chash_unlock(hfsmp);
 466 }
 467
 468
 469 /*
 470  * Remove a cnode from the hash table.
 471  */
 472 __private_extern__
 473 int
 474 hfs_chashremove(struct hfsmount *hfsmp, struct cnode *cp)
 475 {
 476         hfs_chash_lock_spin(hfsmp);
 477
 478         /* Check if a vnode is getting attached */
 479         if (ISSET(cp->c_hflag, H_ATTACH)) {
 480                 hfs_chash_unlock(hfsmp);
 481                 return (EBUSY);
 482         }
 483         if (cp->c_hash.le_next || cp->c_hash.le_prev) {
 484             LIST_REMOVE(cp, c_hash);
 485             cp->c_hash.le_next = NULL;
 486             cp->c_hash.le_prev = NULL;
 487         }
 488         hfs_chash_unlock(hfsmp);
 489
 490         return (0);
 491 }
 492
 493 /*
 494  * Remove a cnode from the hash table and wakeup any waiters.
 495  */
 496 __private_extern__
 497 void
 498 hfs_chash_abort(struct hfsmount *hfsmp, struct cnode *cp)
 499 {
 500         hfs_chash_lock_spin(hfsmp);
 501
 502         LIST_REMOVE(cp, c_hash);
 503         cp->c_hash.le_next = NULL;
 504         cp->c_hash.le_prev = NULL;
 505
 506         CLR(cp->c_hflag, H_ATTACH | H_ALLOC);
 507         if (ISSET(cp->c_hflag, H_WAITING)) {
 508                 CLR(cp->c_hflag, H_WAITING);
 509                 wakeup((caddr_t)cp);
 510         }
 511         hfs_chash_unlock(hfsmp);
 512 }
 513
 514
 515 /*
 516  * mark a cnode as in transition
 517  */
 518 __private_extern__
 519 void
 520 hfs_chash_mark_in_transit(struct hfsmount *hfsmp, struct cnode *cp)
 521 {
 522         hfs_chash_lock_spin(hfsmp);
 523
 524         SET(cp->c_hflag, H_TRANSIT);
 525
 526         hfs_chash_unlock(hfsmp);
 527 }
 528
 529 /* Search a cnode in the hash.  This function does not return cnode which
 530  * are getting created, destroyed or in transition.  Note that this function
 531  * does not acquire the cnode hash mutex, and expects the caller to acquire it.
 532  * On success, returns pointer to the cnode found.  On failure, returns NULL.
 533  */
 534 static
 535 struct cnode *
 536 hfs_chash_search_cnid(struct hfsmount *hfsmp, cnid_t cnid)
 537 {
 538         struct cnode *cp;
 539
 540         for (cp = CNODEHASH(hfsmp, cnid)->lh_first; cp; cp = cp->c_hash.le_next) {
 541                 if (cp->c_fileid == cnid) {
 542                         break;
 543                 }
 544         }
 545
 546         /* If cnode is being created or reclaimed, return error. */
 547         if (cp && ISSET(cp->c_hflag, H_ALLOC | H_TRANSIT | H_ATTACH)) {
 548                 cp = NULL;
 549         }
 550
 551         return cp;
 552 }
 553
 554 /* Search a cnode corresponding to given device and ID in the hash.  If the
 555  * found cnode has kHFSHasChildLinkBit cleared, set it.  If the cnode is not
 556  * found, no new cnode is created and error is returned.
 557  *
 558  * Return values -
 559  *      -1 : The cnode was not found.
 560  *       0 : The cnode was found, and the kHFSHasChildLinkBit was already set.
 561  *       1 : The cnode was found, the kHFSHasChildLinkBit was not set, and the
 562  *           function had to set that bit.
 563  */
 564 __private_extern__
 565 int
 566 hfs_chash_set_childlinkbit(struct hfsmount *hfsmp, cnid_t cnid)
 567 {
 568         int retval = -1;
 569         struct cnode *cp;
 570
 571         hfs_chash_lock_spin(hfsmp);
 572
 573         cp = hfs_chash_search_cnid(hfsmp, cnid);
 574         if (cp) {
 575                 if (cp->c_attr.ca_recflags & kHFSHasChildLinkMask) {
 576                         retval = 0;
 577                 } else {
 578                         cp->c_attr.ca_recflags |= kHFSHasChildLinkMask;
 579                         retval = 1;
 580                 }
 581         }
 582         hfs_chash_unlock(hfsmp);
 583
 584         return retval;
 585 }