1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2013 by Delphix. All rights reserved.
  24  */
  25 
  26 #include <sys/types.h>
  27 #include <sys/param.h>
  28 #include <sys/time.h>
  29 #include <sys/systm.h>
  30 #include <sys/sysmacros.h>
  31 #include <sys/resource.h>
  32 #include <sys/vfs.h>
  33 #include <sys/vnode.h>
  34 #include <sys/file.h>
  35 #include <sys/mode.h>
  36 #include <sys/kmem.h>
  37 #include <sys/uio.h>
  38 #include <sys/pathname.h>
  39 #include <sys/cmn_err.h>
  40 #include <sys/errno.h>
  41 #include <sys/stat.h>
  42 #include <sys/unistd.h>
  43 #include <sys/sunddi.h>
  44 #include <sys/random.h>
  45 #include <sys/policy.h>
  46 #include <sys/zfs_dir.h>
  47 #include <sys/zfs_acl.h>
  48 #include <sys/fs/zfs.h>
  49 #include "fs/fs_subr.h"
  50 #include <sys/zap.h>
  51 #include <sys/dmu.h>
  52 #include <sys/atomic.h>
  53 #include <sys/zfs_ctldir.h>
  54 #include <sys/zfs_fuid.h>
  55 #include <sys/sa.h>
  56 #include <sys/zfs_sa.h>
  57 #include <sys/dnlc.h>
  58 #include <sys/extdirent.h>
  59 
  60 /*
  61  * zfs_match_find() is used by zfs_dirent_lock() to peform zap lookups
  62  * of names after deciding which is the appropriate lookup interface.
  63  */
  64 static int
  65 zfs_match_find(zfsvfs_t *zfsvfs, znode_t *dzp, char *name, boolean_t exact,
  66     boolean_t update, int *deflags, pathname_t *rpnp, uint64_t *zoid)
  67 {
  68         int error;
  69 
  70         if (zfsvfs->z_norm) {
  71                 matchtype_t mt = MT_FIRST;
  72                 boolean_t conflict = B_FALSE;
  73                 size_t bufsz = 0;
  74                 char *buf = NULL;
  75 
  76                 if (rpnp) {
  77                         buf = rpnp->pn_buf;
  78                         bufsz = rpnp->pn_bufsize;
  79                 }
  80                 if (exact)
  81                         mt = MT_EXACT;
  82                 /*
  83                  * In the non-mixed case we only expect there would ever
  84                  * be one match, but we need to use the normalizing lookup.
  85                  */
  86                 error = zap_lookup_norm(zfsvfs->z_os, dzp->z_id, name, 8, 1,
  87                     zoid, mt, buf, bufsz, &conflict);
  88                 if (!error && deflags)
  89                         *deflags = conflict ? ED_CASE_CONFLICT : 0;
  90         } else {
  91                 error = zap_lookup(zfsvfs->z_os, dzp->z_id, name, 8, 1, zoid);
  92         }
  93         *zoid = ZFS_DIRENT_OBJ(*zoid);
  94 
  95         if (error == ENOENT && update)
  96                 dnlc_update(ZTOV(dzp), name, DNLC_NO_VNODE);
  97 
  98         return (error);
  99 }
 100 
 101 /*
 102  * Lock a directory entry.  A dirlock on <dzp, name> protects that name
 103  * in dzp's directory zap object.  As long as you hold a dirlock, you can
 104  * assume two things: (1) dzp cannot be reaped, and (2) no other thread
 105  * can change the zap entry for (i.e. link or unlink) this name.
 106  *
 107  * Input arguments:
 108  *      dzp     - znode for directory
 109  *      name    - name of entry to lock
 110  *      flag    - ZNEW: if the entry already exists, fail with EEXIST.
 111  *                ZEXISTS: if the entry does not exist, fail with ENOENT.
 112  *                ZSHARED: allow concurrent access with other ZSHARED callers.
 113  *                ZXATTR: we want dzp's xattr directory
 114  *                ZCILOOK: On a mixed sensitivity file system,
 115  *                         this lookup should be case-insensitive.
 116  *                ZCIEXACT: On a purely case-insensitive file system,
 117  *                          this lookup should be case-sensitive.
 118  *                ZRENAMING: we are locking for renaming, force narrow locks
 119  *                ZHAVELOCK: Don't grab the z_name_lock for this call. The
 120  *                           current thread already holds it.
 121  *
 122  * Output arguments:
 123  *      zpp     - pointer to the znode for the entry (NULL if there isn't one)
 124  *      dlpp    - pointer to the dirlock for this entry (NULL on error)
 125  *      direntflags - (case-insensitive lookup only)
 126  *              flags if multiple case-sensitive matches exist in directory
 127  *      realpnp     - (case-insensitive lookup only)
 128  *              actual name matched within the directory
 129  *
 130  * Return value: 0 on success or errno on failure.
 131  *
 132  * NOTE: Always checks for, and rejects, '.' and '..'.
 133  * NOTE: For case-insensitive file systems we take wide locks (see below),
 134  *       but return znode pointers to a single match.
 135  */
 136 int
 137 zfs_dirent_lock(zfs_dirlock_t **dlpp, znode_t *dzp, char *name, znode_t **zpp,
 138     int flag, int *direntflags, pathname_t *realpnp)
 139 {
 140         zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
 141         zfs_dirlock_t   *dl;
 142         boolean_t       update;
 143         boolean_t       exact;
 144         uint64_t        zoid;
 145         vnode_t         *vp = NULL;
 146         int             error = 0;
 147         int             cmpflags;
 148 
 149         *zpp = NULL;
 150         *dlpp = NULL;
 151 
 152         /*
 153          * Verify that we are not trying to lock '.', '..', or '.zfs'
 154          */
 155         if (name[0] == '.' &&
 156             (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')) ||
 157             zfs_has_ctldir(dzp) && strcmp(name, ZFS_CTLDIR_NAME) == 0)
 158                 return (SET_ERROR(EEXIST));
 159 
 160         /*
 161          * Case sensitivity and normalization preferences are set when
 162          * the file system is created.  These are stored in the
 163          * zfsvfs->z_case and zfsvfs->z_norm fields.  These choices
 164          * affect what vnodes can be cached in the DNLC, how we
 165          * perform zap lookups, and the "width" of our dirlocks.
 166          *
 167          * A normal dirlock locks a single name.  Note that with
 168          * normalization a name can be composed multiple ways, but
 169          * when normalized, these names all compare equal.  A wide
 170          * dirlock locks multiple names.  We need these when the file
 171          * system is supporting mixed-mode access.  It is sometimes
 172          * necessary to lock all case permutations of file name at
 173          * once so that simultaneous case-insensitive/case-sensitive
 174          * behaves as rationally as possible.
 175          */
 176 
 177         /*
 178          * Decide if exact matches should be requested when performing
 179          * a zap lookup on file systems supporting case-insensitive
 180          * access.
 181          */
 182         exact =
 183             ((zfsvfs->z_case == ZFS_CASE_INSENSITIVE) && (flag & ZCIEXACT)) ||
 184             ((zfsvfs->z_case == ZFS_CASE_MIXED) && !(flag & ZCILOOK));
 185 
 186         /*
 187          * Only look in or update the DNLC if we are looking for the
 188          * name on a file system that does not require normalization
 189          * or case folding.  We can also look there if we happen to be
 190          * on a non-normalizing, mixed sensitivity file system IF we
 191          * are looking for the exact name.
 192          *
 193          * Maybe can add TO-UPPERed version of name to dnlc in ci-only
 194          * case for performance improvement?
 195          */
 196         update = !zfsvfs->z_norm ||
 197             ((zfsvfs->z_case == ZFS_CASE_MIXED) &&
 198             !(zfsvfs->z_norm & ~U8_TEXTPREP_TOUPPER) && !(flag & ZCILOOK));
 199 
 200         /*
 201          * ZRENAMING indicates we are in a situation where we should
 202          * take narrow locks regardless of the file system's
 203          * preferences for normalizing and case folding.  This will
 204          * prevent us deadlocking trying to grab the same wide lock
 205          * twice if the two names happen to be case-insensitive
 206          * matches.
 207          */
 208         if (flag & ZRENAMING)
 209                 cmpflags = 0;
 210         else
 211                 cmpflags = zfsvfs->z_norm;
 212 
 213         /*
 214          * Wait until there are no locks on this name.
 215          *
 216          * Don't grab the the lock if it is already held. However, cannot
 217          * have both ZSHARED and ZHAVELOCK together.
 218          */
 219         ASSERT(!(flag & ZSHARED) || !(flag & ZHAVELOCK));
 220         if (!(flag & ZHAVELOCK))
 221                 rw_enter(&dzp->z_name_lock, RW_READER);
 222 
 223         mutex_enter(&dzp->z_lock);
 224         for (;;) {
 225                 if (dzp->z_unlinked) {
 226                         mutex_exit(&dzp->z_lock);
 227                         if (!(flag & ZHAVELOCK))
 228                                 rw_exit(&dzp->z_name_lock);
 229                         return (SET_ERROR(ENOENT));
 230                 }
 231                 for (dl = dzp->z_dirlocks; dl != NULL; dl = dl->dl_next) {
 232                         if ((u8_strcmp(name, dl->dl_name, 0, cmpflags,
 233                             U8_UNICODE_LATEST, &error) == 0) || error != 0)
 234                                 break;
 235                 }
 236                 if (error != 0) {
 237                         mutex_exit(&dzp->z_lock);
 238                         if (!(flag & ZHAVELOCK))
 239                                 rw_exit(&dzp->z_name_lock);
 240                         return (SET_ERROR(ENOENT));
 241                 }
 242                 if (dl == NULL) {
 243                         /*
 244                          * Allocate a new dirlock and add it to the list.
 245                          */
 246                         dl = kmem_alloc(sizeof (zfs_dirlock_t), KM_SLEEP);
 247                         cv_init(&dl->dl_cv, NULL, CV_DEFAULT, NULL);
 248                         dl->dl_name = name;
 249                         dl->dl_sharecnt = 0;
 250                         dl->dl_namelock = 0;
 251                         dl->dl_namesize = 0;
 252                         dl->dl_dzp = dzp;
 253                         dl->dl_next = dzp->z_dirlocks;
 254                         dzp->z_dirlocks = dl;
 255                         break;
 256                 }
 257                 if ((flag & ZSHARED) && dl->dl_sharecnt != 0)
 258                         break;
 259                 cv_wait(&dl->dl_cv, &dzp->z_lock);
 260         }
 261 
 262         /*
 263          * If the z_name_lock was NOT held for this dirlock record it.
 264          */
 265         if (flag & ZHAVELOCK)
 266                 dl->dl_namelock = 1;
 267 
 268         if ((flag & ZSHARED) && ++dl->dl_sharecnt > 1 && dl->dl_namesize == 0) {
 269                 /*
 270                  * We're the second shared reference to dl.  Make a copy of
 271                  * dl_name in case the first thread goes away before we do.
 272                  * Note that we initialize the new name before storing its
 273                  * pointer into dl_name, because the first thread may load
 274                  * dl->dl_name at any time.  He'll either see the old value,
 275                  * which is his, or the new shared copy; either is OK.
 276                  */
 277                 dl->dl_namesize = strlen(dl->dl_name) + 1;
 278                 name = kmem_alloc(dl->dl_namesize, KM_SLEEP);
 279                 bcopy(dl->dl_name, name, dl->dl_namesize);
 280                 dl->dl_name = name;
 281         }
 282 
 283         mutex_exit(&dzp->z_lock);
 284 
 285         /*
 286          * We have a dirlock on the name.  (Note that it is the dirlock,
 287          * not the dzp's z_lock, that protects the name in the zap object.)
 288          * See if there's an object by this name; if so, put a hold on it.
 289          */
 290         if (flag & ZXATTR) {
 291                 error = sa_lookup(dzp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs), &zoid,
 292                     sizeof (zoid));
 293                 if (error == 0)
 294                         error = (zoid == 0 ? ENOENT : 0);
 295         } else {
 296                 if (update)
 297                         vp = dnlc_lookup(ZTOV(dzp), name);
 298                 if (vp == DNLC_NO_VNODE) {
 299                         VN_RELE(vp);
 300                         error = SET_ERROR(ENOENT);
 301                 } else if (vp) {
 302                         if (flag & ZNEW) {
 303                                 zfs_dirent_unlock(dl);
 304                                 VN_RELE(vp);
 305                                 return (SET_ERROR(EEXIST));
 306                         }
 307                         *dlpp = dl;
 308                         *zpp = VTOZ(vp);
 309                         return (0);
 310                 } else {
 311                         error = zfs_match_find(zfsvfs, dzp, name, exact,
 312                             update, direntflags, realpnp, &zoid);
 313                 }
 314         }
 315         if (error) {
 316                 if (error != ENOENT || (flag & ZEXISTS)) {
 317                         zfs_dirent_unlock(dl);
 318                         return (error);
 319                 }
 320         } else {
 321                 if (flag & ZNEW) {
 322                         zfs_dirent_unlock(dl);
 323                         return (SET_ERROR(EEXIST));
 324                 }
 325                 error = zfs_zget(zfsvfs, zoid, zpp);
 326                 if (error) {
 327                         zfs_dirent_unlock(dl);
 328                         return (error);
 329                 }
 330                 if (!(flag & ZXATTR) && update)
 331                         dnlc_update(ZTOV(dzp), name, ZTOV(*zpp));
 332         }
 333 
 334         *dlpp = dl;
 335 
 336         return (0);
 337 }
 338 
 339 /*
 340  * Unlock this directory entry and wake anyone who was waiting for it.
 341  */
 342 void
 343 zfs_dirent_unlock(zfs_dirlock_t *dl)
 344 {
 345         znode_t *dzp = dl->dl_dzp;
 346         zfs_dirlock_t **prev_dl, *cur_dl;
 347 
 348         mutex_enter(&dzp->z_lock);
 349 
 350         if (!dl->dl_namelock)
 351                 rw_exit(&dzp->z_name_lock);
 352 
 353         if (dl->dl_sharecnt > 1) {
 354                 dl->dl_sharecnt--;
 355                 mutex_exit(&dzp->z_lock);
 356                 return;
 357         }
 358         prev_dl = &dzp->z_dirlocks;
 359         while ((cur_dl = *prev_dl) != dl)
 360                 prev_dl = &cur_dl->dl_next;
 361         *prev_dl = dl->dl_next;
 362         cv_broadcast(&dl->dl_cv);
 363         mutex_exit(&dzp->z_lock);
 364 
 365         if (dl->dl_namesize != 0)
 366                 kmem_free(dl->dl_name, dl->dl_namesize);
 367         cv_destroy(&dl->dl_cv);
 368         kmem_free(dl, sizeof (*dl));
 369 }
 370 
 371 /*
 372  * Look up an entry in a directory.
 373  *
 374  * NOTE: '.' and '..' are handled as special cases because
 375  *      no directory entries are actually stored for them.  If this is
 376  *      the root of a filesystem, then '.zfs' is also treated as a
 377  *      special pseudo-directory.
 378  */
 379 int
 380 zfs_dirlook(znode_t *dzp, char *name, vnode_t **vpp, int flags,
 381     int *deflg, pathname_t *rpnp)
 382 {
 383         zfs_dirlock_t *dl;
 384         znode_t *zp;
 385         int error = 0;
 386         uint64_t parent;
 387 
 388         if (name[0] == 0 || (name[0] == '.' && name[1] == 0)) {
 389                 *vpp = ZTOV(dzp);
 390                 VN_HOLD(*vpp);
 391         } else if (name[0] == '.' && name[1] == '.' && name[2] == 0) {
 392                 zfsvfs_t *zfsvfs = dzp->z_zfsvfs;
 393 
 394                 /*
 395                  * If we are a snapshot mounted under .zfs, return
 396                  * the vp for the snapshot directory.
 397                  */
 398                 if ((error = sa_lookup(dzp->z_sa_hdl,
 399                     SA_ZPL_PARENT(zfsvfs), &parent, sizeof (parent))) != 0)
 400                         return (error);
 401                 if (parent == dzp->z_id && zfsvfs->z_parent != zfsvfs) {
 402                         error = zfsctl_root_lookup(zfsvfs->z_parent->z_ctldir,
 403                             "snapshot", vpp, NULL, 0, NULL, kcred,
 404                             NULL, NULL, NULL);
 405                         return (error);
 406                 }
 407                 rw_enter(&dzp->z_parent_lock, RW_READER);
 408                 error = zfs_zget(zfsvfs, parent, &zp);
 409                 if (error == 0)
 410                         *vpp = ZTOV(zp);
 411                 rw_exit(&dzp->z_parent_lock);
 412         } else if (zfs_has_ctldir(dzp) && strcmp(name, ZFS_CTLDIR_NAME) == 0) {
 413                 *vpp = zfsctl_root(dzp);
 414         } else {
 415                 int zf;
 416 
 417                 zf = ZEXISTS | ZSHARED;
 418                 if (flags & FIGNORECASE)
 419                         zf |= ZCILOOK;
 420 
 421                 error = zfs_dirent_lock(&dl, dzp, name, &zp, zf, deflg, rpnp);
 422                 if (error == 0) {
 423                         *vpp = ZTOV(zp);
 424                         zfs_dirent_unlock(dl);
 425                         dzp->z_zn_prefetch = B_TRUE; /* enable prefetching */
 426                 }
 427                 rpnp = NULL;
 428         }
 429 
 430         if ((flags & FIGNORECASE) && rpnp && !error)
 431                 (void) strlcpy(rpnp->pn_buf, name, rpnp->pn_bufsize);
 432 
 433         return (error);
 434 }
 435 
 436 /*
 437  * unlinked Set (formerly known as the "delete queue") Error Handling
 438  *
 439  * When dealing with the unlinked set, we dmu_tx_hold_zap(), but we
 440  * don't specify the name of the entry that we will be manipulating.  We
 441  * also fib and say that we won't be adding any new entries to the
 442  * unlinked set, even though we might (this is to lower the minimum file
 443  * size that can be deleted in a full filesystem).  So on the small
 444  * chance that the nlink list is using a fat zap (ie. has more than
 445  * 2000 entries), we *may* not pre-read a block that's needed.
 446  * Therefore it is remotely possible for some of the assertions
 447  * regarding the unlinked set below to fail due to i/o error.  On a
 448  * nondebug system, this will result in the space being leaked.
 449  */
 450 void
 451 zfs_unlinked_add(znode_t *zp, dmu_tx_t *tx)
 452 {
 453         zfsvfs_t *zfsvfs = zp->z_zfsvfs;
 454 
 455         ASSERT(zp->z_unlinked);
 456         ASSERT(zp->z_links == 0);
 457 
 458         VERIFY3U(0, ==,
 459             zap_add_int(zfsvfs->z_os, zfsvfs->z_unlinkedobj, zp->z_id, tx));
 460 }
 461 
 462 /*
 463  * Clean up any znodes that had no links when we either crashed or
 464  * (force) umounted the file system.
 465  */
 466 void
 467 zfs_unlinked_drain(zfsvfs_t *zfsvfs)
 468 {
 469         zap_cursor_t    zc;
 470         zap_attribute_t zap;
 471         dmu_object_info_t doi;
 472         znode_t         *zp;
 473         int             error;
 474 
 475         /*
 476          * Interate over the contents of the unlinked set.
 477          */
 478         for (zap_cursor_init(&zc, zfsvfs->z_os, zfsvfs->z_unlinkedobj);
 479             zap_cursor_retrieve(&zc, &zap) == 0;
 480             zap_cursor_advance(&zc)) {
 481 
 482                 /*
 483                  * See what kind of object we have in list
 484                  */
 485 
 486                 error = dmu_object_info(zfsvfs->z_os,
 487                     zap.za_first_integer, &doi);
 488                 if (error != 0)
 489                         continue;
 490 
 491                 ASSERT((doi.doi_type == DMU_OT_PLAIN_FILE_CONTENTS) ||
 492                     (doi.doi_type == DMU_OT_DIRECTORY_CONTENTS));
 493                 /*
 494                  * We need to re-mark these list entries for deletion,
 495                  * so we pull them back into core and set zp->z_unlinked.
 496                  */
 497                 error = zfs_zget(zfsvfs, zap.za_first_integer, &zp);
 498 
 499                 /*
 500                  * We may pick up znodes that are already marked for deletion.
 501                  * This could happen during the purge of an extended attribute
 502                  * directory.  All we need to do is skip over them, since they
 503                  * are already in the system marked z_unlinked.
 504                  */
 505                 if (error != 0)
 506                         continue;
 507 
 508                 zp->z_unlinked = B_TRUE;
 509                 VN_RELE(ZTOV(zp));
 510         }
 511         zap_cursor_fini(&zc);
 512 }
 513 
 514 /*
 515  * Delete the entire contents of a directory.  Return a count
 516  * of the number of entries that could not be deleted. If we encounter
 517  * an error, return a count of at least one so that the directory stays
 518  * in the unlinked set.
 519  *
 520  * NOTE: this function assumes that the directory is inactive,
 521  *      so there is no need to lock its entries before deletion.
 522  *      Also, it assumes the directory contents is *only* regular
 523  *      files.
 524  */
 525 static int
 526 zfs_purgedir(znode_t *dzp)
 527 {
 528         zap_cursor_t    zc;
 529         zap_attribute_t zap;
 530         znode_t         *xzp;
 531         dmu_tx_t        *tx;
 532         zfsvfs_t        *zfsvfs = dzp->z_zfsvfs;
 533         zfs_dirlock_t   dl;
 534         int skipped = 0;
 535         int error;
 536 
 537         for (zap_cursor_init(&zc, zfsvfs->z_os, dzp->z_id);
 538             (error = zap_cursor_retrieve(&zc, &zap)) == 0;
 539             zap_cursor_advance(&zc)) {
 540                 error = zfs_zget(zfsvfs,
 541                     ZFS_DIRENT_OBJ(zap.za_first_integer), &xzp);
 542                 if (error) {
 543                         skipped += 1;
 544                         continue;
 545                 }
 546 
 547                 ASSERT((ZTOV(xzp)->v_type == VREG) ||
 548                     (ZTOV(xzp)->v_type == VLNK));
 549 
 550                 tx = dmu_tx_create(zfsvfs->z_os);
 551                 dmu_tx_hold_sa(tx, dzp->z_sa_hdl, B_FALSE);
 552                 dmu_tx_hold_zap(tx, dzp->z_id, FALSE, zap.za_name);
 553                 dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
 554                 dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
 555                 /* Is this really needed ? */
 556                 zfs_sa_upgrade_txholds(tx, xzp);
 557                 error = dmu_tx_assign(tx, TXG_WAIT);
 558                 if (error) {
 559                         dmu_tx_abort(tx);
 560                         VN_RELE(ZTOV(xzp));
 561                         skipped += 1;
 562                         continue;
 563                 }
 564                 bzero(&dl, sizeof (dl));
 565                 dl.dl_dzp = dzp;
 566                 dl.dl_name = zap.za_name;
 567 
 568                 error = zfs_link_destroy(&dl, xzp, tx, 0, NULL);
 569                 if (error)
 570                         skipped += 1;
 571                 dmu_tx_commit(tx);
 572 
 573                 VN_RELE(ZTOV(xzp));
 574         }
 575         zap_cursor_fini(&zc);
 576         if (error != ENOENT)
 577                 skipped += 1;
 578         return (skipped);
 579 }
 580 
 581 void
 582 zfs_rmnode(znode_t *zp)
 583 {
 584         zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
 585         objset_t        *os = zfsvfs->z_os;
 586         znode_t         *xzp = NULL;
 587         dmu_tx_t        *tx;
 588         uint64_t        acl_obj;
 589         uint64_t        xattr_obj;
 590         int             error;
 591 
 592         ASSERT(zp->z_links == 0);
 593         ASSERT(ZTOV(zp)->v_count == 0);
 594 
 595         /*
 596          * If this is an attribute directory, purge its contents.
 597          */
 598         if (ZTOV(zp)->v_type == VDIR && (zp->z_pflags & ZFS_XATTR)) {
 599                 if (zfs_purgedir(zp) != 0) {
 600                         /*
 601                          * Not enough space to delete some xattrs.
 602                          * Leave it in the unlinked set.
 603                          */
 604                         zfs_znode_dmu_fini(zp);
 605                         zfs_znode_free(zp);
 606                         return;
 607                 }
 608         }
 609 
 610         /*
 611          * Free up all the data in the file.
 612          */
 613         error = dmu_free_long_range(os, zp->z_id, 0, DMU_OBJECT_END);
 614         if (error) {
 615                 /*
 616                  * Not enough space.  Leave the file in the unlinked set.
 617                  */
 618                 zfs_znode_dmu_fini(zp);
 619                 zfs_znode_free(zp);
 620                 return;
 621         }
 622 
 623         /*
 624          * If the file has extended attributes, we're going to unlink
 625          * the xattr dir.
 626          */
 627         error = sa_lookup(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs),
 628             &xattr_obj, sizeof (xattr_obj));
 629         if (error == 0 && xattr_obj) {
 630                 error = zfs_zget(zfsvfs, xattr_obj, &xzp);
 631                 ASSERT(error == 0);
 632         }
 633 
 634         acl_obj = zfs_external_acl(zp);
 635 
 636         /*
 637          * Set up the final transaction.
 638          */
 639         tx = dmu_tx_create(os);
 640         dmu_tx_hold_free(tx, zp->z_id, 0, DMU_OBJECT_END);
 641         dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, FALSE, NULL);
 642         if (xzp) {
 643                 dmu_tx_hold_zap(tx, zfsvfs->z_unlinkedobj, TRUE, NULL);
 644                 dmu_tx_hold_sa(tx, xzp->z_sa_hdl, B_FALSE);
 645         }
 646         if (acl_obj)
 647                 dmu_tx_hold_free(tx, acl_obj, 0, DMU_OBJECT_END);
 648 
 649         zfs_sa_upgrade_txholds(tx, zp);
 650         error = dmu_tx_assign(tx, TXG_WAIT);
 651         if (error) {
 652                 /*
 653                  * Not enough space to delete the file.  Leave it in the
 654                  * unlinked set, leaking it until the fs is remounted (at
 655                  * which point we'll call zfs_unlinked_drain() to process it).
 656                  */
 657                 dmu_tx_abort(tx);
 658                 zfs_znode_dmu_fini(zp);
 659                 zfs_znode_free(zp);
 660                 goto out;
 661         }
 662 
 663         if (xzp) {
 664                 ASSERT(error == 0);
 665                 mutex_enter(&xzp->z_lock);
 666                 xzp->z_unlinked = B_TRUE;    /* mark xzp for deletion */
 667                 xzp->z_links = 0;    /* no more links to it */
 668                 VERIFY(0 == sa_update(xzp->z_sa_hdl, SA_ZPL_LINKS(zfsvfs),
 669                     &xzp->z_links, sizeof (xzp->z_links), tx));
 670                 mutex_exit(&xzp->z_lock);
 671                 zfs_unlinked_add(xzp, tx);
 672         }
 673 
 674         /* Remove this znode from the unlinked set */
 675         VERIFY3U(0, ==,
 676             zap_remove_int(zfsvfs->z_os, zfsvfs->z_unlinkedobj, zp->z_id, tx));
 677 
 678         zfs_znode_delete(zp, tx);
 679 
 680         dmu_tx_commit(tx);
 681 out:
 682         if (xzp)
 683                 VN_RELE(ZTOV(xzp));
 684 }
 685 
 686 static uint64_t
 687 zfs_dirent(znode_t *zp, uint64_t mode)
 688 {
 689         uint64_t de = zp->z_id;
 690 
 691         if (zp->z_zfsvfs->z_version >= ZPL_VERSION_DIRENT_TYPE)
 692                 de |= IFTODT(mode) << 60;
 693         return (de);
 694 }
 695 
 696 /*
 697  * Link zp into dl.  Can only fail if zp has been unlinked.
 698  */
 699 int
 700 zfs_link_create(zfs_dirlock_t *dl, znode_t *zp, dmu_tx_t *tx, int flag)
 701 {
 702         znode_t *dzp = dl->dl_dzp;
 703         zfsvfs_t *zfsvfs = zp->z_zfsvfs;
 704         vnode_t *vp = ZTOV(zp);
 705         uint64_t value;
 706         int zp_is_dir = (vp->v_type == VDIR);
 707         sa_bulk_attr_t bulk[5];
 708         uint64_t mtime[2], ctime[2];
 709         int count = 0;
 710         int error;
 711 
 712         mutex_enter(&zp->z_lock);
 713 
 714         if (!(flag & ZRENAMING)) {
 715                 if (zp->z_unlinked) {        /* no new links to unlinked zp */
 716                         ASSERT(!(flag & (ZNEW | ZEXISTS)));
 717                         mutex_exit(&zp->z_lock);
 718                         return (SET_ERROR(ENOENT));
 719                 }
 720                 zp->z_links++;
 721                 SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs), NULL,
 722                     &zp->z_links, sizeof (zp->z_links));
 723 
 724         }
 725         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_PARENT(zfsvfs), NULL,
 726             &dzp->z_id, sizeof (dzp->z_id));
 727         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
 728             &zp->z_pflags, sizeof (zp->z_pflags));
 729 
 730         if (!(flag & ZNEW)) {
 731                 SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 732                     ctime, sizeof (ctime));
 733                 zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime,
 734                     ctime, B_TRUE);
 735         }
 736         error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
 737         ASSERT(error == 0);
 738 
 739         mutex_exit(&zp->z_lock);
 740 
 741         mutex_enter(&dzp->z_lock);
 742         dzp->z_size++;
 743         dzp->z_links += zp_is_dir;
 744         count = 0;
 745         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs), NULL,
 746             &dzp->z_size, sizeof (dzp->z_size));
 747         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs), NULL,
 748             &dzp->z_links, sizeof (dzp->z_links));
 749         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs), NULL,
 750             mtime, sizeof (mtime));
 751         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs), NULL,
 752             ctime, sizeof (ctime));
 753         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs), NULL,
 754             &dzp->z_pflags, sizeof (dzp->z_pflags));
 755         zfs_tstamp_update_setup(dzp, CONTENT_MODIFIED, mtime, ctime, B_TRUE);
 756         error = sa_bulk_update(dzp->z_sa_hdl, bulk, count, tx);
 757         ASSERT(error == 0);
 758         mutex_exit(&dzp->z_lock);
 759 
 760         value = zfs_dirent(zp, zp->z_mode);
 761         error = zap_add(zp->z_zfsvfs->z_os, dzp->z_id, dl->dl_name,
 762             8, 1, &value, tx);
 763         ASSERT(error == 0);
 764 
 765         dnlc_update(ZTOV(dzp), dl->dl_name, vp);
 766 
 767         return (0);
 768 }
 769 
 770 static int
 771 zfs_dropname(zfs_dirlock_t *dl, znode_t *zp, znode_t *dzp, dmu_tx_t *tx,
 772     int flag)
 773 {
 774         int error;
 775 
 776         if (zp->z_zfsvfs->z_norm) {
 777                 if (((zp->z_zfsvfs->z_case == ZFS_CASE_INSENSITIVE) &&
 778                     (flag & ZCIEXACT)) ||
 779                     ((zp->z_zfsvfs->z_case == ZFS_CASE_MIXED) &&
 780                     !(flag & ZCILOOK)))
 781                         error = zap_remove_norm(zp->z_zfsvfs->z_os,
 782                             dzp->z_id, dl->dl_name, MT_EXACT, tx);
 783                 else
 784                         error = zap_remove_norm(zp->z_zfsvfs->z_os,
 785                             dzp->z_id, dl->dl_name, MT_FIRST, tx);
 786         } else {
 787                 error = zap_remove(zp->z_zfsvfs->z_os,
 788                     dzp->z_id, dl->dl_name, tx);
 789         }
 790 
 791         return (error);
 792 }
 793 
 794 /*
 795  * Unlink zp from dl, and mark zp for deletion if this was the last link.
 796  * Can fail if zp is a mount point (EBUSY) or a non-empty directory (EEXIST).
 797  * If 'unlinkedp' is NULL, we put unlinked znodes on the unlinked list.
 798  * If it's non-NULL, we use it to indicate whether the znode needs deletion,
 799  * and it's the caller's job to do it.
 800  */
 801 int
 802 zfs_link_destroy(zfs_dirlock_t *dl, znode_t *zp, dmu_tx_t *tx, int flag,
 803         boolean_t *unlinkedp)
 804 {
 805         znode_t *dzp = dl->dl_dzp;
 806         zfsvfs_t *zfsvfs = dzp->z_zfsvfs;
 807         vnode_t *vp = ZTOV(zp);
 808         int zp_is_dir = (vp->v_type == VDIR);
 809         boolean_t unlinked = B_FALSE;
 810         sa_bulk_attr_t bulk[5];
 811         uint64_t mtime[2], ctime[2];
 812         int count = 0;
 813         int error;
 814 
 815         dnlc_remove(ZTOV(dzp), dl->dl_name);
 816 
 817         if (!(flag & ZRENAMING)) {
 818                 if (vn_vfswlock(vp))            /* prevent new mounts on zp */
 819                         return (SET_ERROR(EBUSY));
 820 
 821                 if (vn_ismntpt(vp)) {           /* don't remove mount point */
 822                         vn_vfsunlock(vp);
 823                         return (SET_ERROR(EBUSY));
 824                 }
 825 
 826                 mutex_enter(&zp->z_lock);
 827 
 828                 if (zp_is_dir && !zfs_dirempty(zp)) {
 829                         mutex_exit(&zp->z_lock);
 830                         vn_vfsunlock(vp);
 831                         return (SET_ERROR(EEXIST));
 832                 }
 833 
 834                 /*
 835                  * If we get here, we are going to try to remove the object.
 836                  * First try removing the name from the directory; if that
 837                  * fails, return the error.
 838                  */
 839                 error = zfs_dropname(dl, zp, dzp, tx, flag);
 840                 if (error != 0) {
 841                         mutex_exit(&zp->z_lock);
 842                         vn_vfsunlock(vp);
 843                         return (error);
 844                 }
 845 
 846                 if (zp->z_links <= zp_is_dir) {
 847                         zfs_panic_recover("zfs: link count on %s is %u, "
 848                             "should be at least %u",
 849                             zp->z_vnode->v_path ? zp->z_vnode->v_path :
 850                             "<unknown>", (int)zp->z_links,
 851                             zp_is_dir + 1);
 852                         zp->z_links = zp_is_dir + 1;
 853                 }
 854                 if (--zp->z_links == zp_is_dir) {
 855                         zp->z_unlinked = B_TRUE;
 856                         zp->z_links = 0;
 857                         unlinked = B_TRUE;
 858                 } else {
 859                         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
 860                             NULL, &ctime, sizeof (ctime));
 861                         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
 862                             NULL, &zp->z_pflags, sizeof (zp->z_pflags));
 863                         zfs_tstamp_update_setup(zp, STATE_CHANGED, mtime, ctime,
 864                             B_TRUE);
 865                 }
 866                 SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
 867                     NULL, &zp->z_links, sizeof (zp->z_links));
 868                 error = sa_bulk_update(zp->z_sa_hdl, bulk, count, tx);
 869                 count = 0;
 870                 ASSERT(error == 0);
 871                 mutex_exit(&zp->z_lock);
 872                 vn_vfsunlock(vp);
 873         } else {
 874                 error = zfs_dropname(dl, zp, dzp, tx, flag);
 875                 if (error != 0)
 876                         return (error);
 877         }
 878 
 879         mutex_enter(&dzp->z_lock);
 880         dzp->z_size--;               /* one dirent removed */
 881         dzp->z_links -= zp_is_dir;   /* ".." link from zp */
 882         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_LINKS(zfsvfs),
 883             NULL, &dzp->z_links, sizeof (dzp->z_links));
 884         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_SIZE(zfsvfs),
 885             NULL, &dzp->z_size, sizeof (dzp->z_size));
 886         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_CTIME(zfsvfs),
 887             NULL, ctime, sizeof (ctime));
 888         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_MTIME(zfsvfs),
 889             NULL, mtime, sizeof (mtime));
 890         SA_ADD_BULK_ATTR(bulk, count, SA_ZPL_FLAGS(zfsvfs),
 891             NULL, &dzp->z_pflags, sizeof (dzp->z_pflags));
 892         zfs_tstamp_update_setup(dzp, CONTENT_MODIFIED, mtime, ctime, B_TRUE);
 893         error = sa_bulk_update(dzp->z_sa_hdl, bulk, count, tx);
 894         ASSERT(error == 0);
 895         mutex_exit(&dzp->z_lock);
 896 
 897         if (unlinkedp != NULL)
 898                 *unlinkedp = unlinked;
 899         else if (unlinked)
 900                 zfs_unlinked_add(zp, tx);
 901 
 902         return (0);
 903 }
 904 
 905 /*
 906  * Indicate whether the directory is empty.  Works with or without z_lock
 907  * held, but can only be consider a hint in the latter case.  Returns true
 908  * if only "." and ".." remain and there's no work in progress.
 909  */
 910 boolean_t
 911 zfs_dirempty(znode_t *dzp)
 912 {
 913         return (dzp->z_size == 2 && dzp->z_dirlocks == 0);
 914 }
 915 
 916 int
 917 zfs_make_xattrdir(znode_t *zp, vattr_t *vap, vnode_t **xvpp, cred_t *cr)
 918 {
 919         zfsvfs_t *zfsvfs = zp->z_zfsvfs;
 920         znode_t *xzp;
 921         dmu_tx_t *tx;
 922         int error;
 923         zfs_acl_ids_t acl_ids;
 924         boolean_t fuid_dirtied;
 925         uint64_t parent;
 926 
 927         *xvpp = NULL;
 928 
 929         if (error = zfs_zaccess(zp, ACE_WRITE_NAMED_ATTRS, 0, B_FALSE, cr))
 930                 return (error);
 931 
 932         if ((error = zfs_acl_ids_create(zp, IS_XATTR, vap, cr, NULL,
 933             &acl_ids)) != 0)
 934                 return (error);
 935         if (zfs_acl_ids_overquota(zfsvfs, &acl_ids)) {
 936                 zfs_acl_ids_free(&acl_ids);
 937                 return (SET_ERROR(EDQUOT));
 938         }
 939 
 940         tx = dmu_tx_create(zfsvfs->z_os);
 941         dmu_tx_hold_sa_create(tx, acl_ids.z_aclp->z_acl_bytes +
 942             ZFS_SA_BASE_ATTR_SIZE);
 943         dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_TRUE);
 944         dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, FALSE, NULL);
 945         fuid_dirtied = zfsvfs->z_fuid_dirty;
 946         if (fuid_dirtied)
 947                 zfs_fuid_txhold(zfsvfs, tx);
 948         error = dmu_tx_assign(tx, TXG_WAIT);
 949         if (error) {
 950                 zfs_acl_ids_free(&acl_ids);
 951                 dmu_tx_abort(tx);
 952                 return (error);
 953         }
 954         zfs_mknode(zp, vap, tx, cr, IS_XATTR, &xzp, &acl_ids);
 955 
 956         if (fuid_dirtied)
 957                 zfs_fuid_sync(zfsvfs, tx);
 958 
 959 #ifdef DEBUG
 960         error = sa_lookup(xzp->z_sa_hdl, SA_ZPL_PARENT(zfsvfs),
 961             &parent, sizeof (parent));
 962         ASSERT(error == 0 && parent == zp->z_id);
 963 #endif
 964 
 965         VERIFY(0 == sa_update(zp->z_sa_hdl, SA_ZPL_XATTR(zfsvfs), &xzp->z_id,
 966             sizeof (xzp->z_id), tx));
 967 
 968         (void) zfs_log_create(zfsvfs->z_log, tx, TX_MKXATTR, zp,
 969             xzp, "", NULL, acl_ids.z_fuidp, vap);
 970 
 971         zfs_acl_ids_free(&acl_ids);
 972         dmu_tx_commit(tx);
 973 
 974         *xvpp = ZTOV(xzp);
 975 
 976         return (0);
 977 }
 978 
 979 /*
 980  * Return a znode for the extended attribute directory for zp.
 981  * ** If the directory does not already exist, it is created **
 982  *
 983  *      IN:     zp      - znode to obtain attribute directory from
 984  *              cr      - credentials of caller
 985  *              flags   - flags from the VOP_LOOKUP call
 986  *
 987  *      OUT:    xzpp    - pointer to extended attribute znode
 988  *
 989  *      RETURN: 0 on success
 990  *              error number on failure
 991  */
 992 int
 993 zfs_get_xattrdir(znode_t *zp, vnode_t **xvpp, cred_t *cr, int flags)
 994 {
 995         zfsvfs_t        *zfsvfs = zp->z_zfsvfs;
 996         znode_t         *xzp;
 997         zfs_dirlock_t   *dl;
 998         vattr_t         va;
 999         int             error;
1000 top:
1001         error = zfs_dirent_lock(&dl, zp, "", &xzp, ZXATTR, NULL, NULL);
1002         if (error)
1003                 return (error);
1004 
1005         if (xzp != NULL) {
1006                 *xvpp = ZTOV(xzp);
1007                 zfs_dirent_unlock(dl);
1008                 return (0);
1009         }
1010 
1011 
1012         if (!(flags & CREATE_XATTR_DIR)) {
1013                 zfs_dirent_unlock(dl);
1014                 return (SET_ERROR(ENOENT));
1015         }
1016 
1017         if (zfsvfs->z_vfs->vfs_flag & VFS_RDONLY) {
1018                 zfs_dirent_unlock(dl);
1019                 return (SET_ERROR(EROFS));
1020         }
1021 
1022         /*
1023          * The ability to 'create' files in an attribute
1024          * directory comes from the write_xattr permission on the base file.
1025          *
1026          * The ability to 'search' an attribute directory requires
1027          * read_xattr permission on the base file.
1028          *
1029          * Once in a directory the ability to read/write attributes
1030          * is controlled by the permissions on the attribute file.
1031          */
1032         va.va_mask = AT_TYPE | AT_MODE | AT_UID | AT_GID;
1033         va.va_type = VDIR;
1034         va.va_mode = S_IFDIR | S_ISVTX | 0777;
1035         zfs_fuid_map_ids(zp, cr, &va.va_uid, &va.va_gid);
1036 
1037         error = zfs_make_xattrdir(zp, &va, xvpp, cr);
1038         zfs_dirent_unlock(dl);
1039 
1040         if (error == ERESTART) {
1041                 /* NB: we already did dmu_tx_wait() if necessary */
1042                 goto top;
1043         }
1044 
1045         return (error);
1046 }
1047 
1048 /*
1049  * Decide whether it is okay to remove within a sticky directory.
1050  *
1051  * In sticky directories, write access is not sufficient;
1052  * you can remove entries from a directory only if:
1053  *
1054  *      you own the directory,
1055  *      you own the entry,
1056  *      the entry is a plain file and you have write access,
1057  *      or you are privileged (checked in secpolicy...).
1058  *
1059  * The function returns 0 if remove access is granted.
1060  */
1061 int
1062 zfs_sticky_remove_access(znode_t *zdp, znode_t *zp, cred_t *cr)
1063 {
1064         uid_t           uid;
1065         uid_t           downer;
1066         uid_t           fowner;
1067         zfsvfs_t        *zfsvfs = zdp->z_zfsvfs;
1068 
1069         if (zdp->z_zfsvfs->z_replay)
1070                 return (0);
1071 
1072         if ((zdp->z_mode & S_ISVTX) == 0)
1073                 return (0);
1074 
1075         downer = zfs_fuid_map_id(zfsvfs, zdp->z_uid, cr, ZFS_OWNER);
1076         fowner = zfs_fuid_map_id(zfsvfs, zp->z_uid, cr, ZFS_OWNER);
1077 
1078         if ((uid = crgetuid(cr)) == downer || uid == fowner ||
1079             (ZTOV(zp)->v_type == VREG &&
1080             zfs_zaccess(zp, ACE_WRITE_DATA, 0, B_FALSE, cr) == 0))
1081                 return (0);
1082         else
1083                 return (secpolicy_vnode_remove(cr));
1084 }