fs/xfs/xfs_attr_list.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2000-2005 Silicon Graphics, Inc.
   4  * Copyright (c) 2013 Red Hat, Inc.
   5  * All Rights Reserved.
   6  */
   7 #include "xfs.h"
   8 #include "xfs_fs.h"
   9 #include "xfs_format.h"
  10 #include "xfs_log_format.h"
  11 #include "xfs_trans_resv.h"
  12 #include "xfs_bit.h"
  13 #include "xfs_mount.h"
  14 #include "xfs_da_format.h"
  15 #include "xfs_da_btree.h"
  16 #include "xfs_inode.h"
  17 #include "xfs_trans.h"
  18 #include "xfs_inode_item.h"
  19 #include "xfs_bmap.h"
  20 #include "xfs_attr.h"
  21 #include "xfs_attr_sf.h"
  22 #include "xfs_attr_remote.h"
  23 #include "xfs_attr_leaf.h"
  24 #include "xfs_error.h"
  25 #include "xfs_trace.h"
  26 #include "xfs_buf_item.h"
  27 #include "xfs_cksum.h"
  28 #include "xfs_dir2.h"
  29
  30 STATIC int
  31 xfs_attr_shortform_compare(const void *a, const void *b)
  32 {
  33         xfs_attr_sf_sort_t *sa, *sb;
  34
  35         sa = (xfs_attr_sf_sort_t *)a;
  36         sb = (xfs_attr_sf_sort_t *)b;
  37         if (sa->hash < sb->hash) {
  38                 return -1;
  39         } else if (sa->hash > sb->hash) {
  40                 return 1;
  41         } else {
  42                 return sa->entno - sb->entno;
  43         }
  44 }
  45
  46 #define XFS_ISRESET_CURSOR(cursor) \
  47         (!((cursor)->initted) && !((cursor)->hashval) && \
  48          !((cursor)->blkno) && !((cursor)->offset))
  49 /*
  50  * Copy out entries of shortform attribute lists for attr_list().
  51  * Shortform attribute lists are not stored in hashval sorted order.
  52  * If the output buffer is not large enough to hold them all, then we
  53  * we have to calculate each entries' hashvalue and sort them before
  54  * we can begin returning them to the user.
  55  */
  56 static int
  57 xfs_attr_shortform_list(xfs_attr_list_context_t *context)
  58 {
  59         attrlist_cursor_kern_t *cursor;
  60         xfs_attr_sf_sort_t *sbuf, *sbp;
  61         xfs_attr_shortform_t *sf;
  62         xfs_attr_sf_entry_t *sfe;
  63         xfs_inode_t *dp;
  64         int sbsize, nsbuf, count, i;
  65
  66         ASSERT(context != NULL);
  67         dp = context->dp;
  68         ASSERT(dp != NULL);
  69         ASSERT(dp->i_afp != NULL);
  70         sf = (xfs_attr_shortform_t *)dp->i_afp->if_u1.if_data;
  71         ASSERT(sf != NULL);
  72         if (!sf->hdr.count)
  73                 return 0;
  74         cursor = context->cursor;
  75         ASSERT(cursor != NULL);
  76
  77         trace_xfs_attr_list_sf(context);
  78
  79         /*
  80          * If the buffer is large enough and the cursor is at the start,
  81          * do not bother with sorting since we will return everything in
  82          * one buffer and another call using the cursor won't need to be
  83          * made.
  84          * Note the generous fudge factor of 16 overhead bytes per entry.
  85          * If bufsize is zero then put_listent must be a search function
  86          * and can just scan through what we have.
  87          */
  88         if (context->bufsize == 0 ||
  89             (XFS_ISRESET_CURSOR(cursor) &&
  90              (dp->i_afp->if_bytes + sf->hdr.count * 16) < context->bufsize)) {
  91                 for (i = 0, sfe = &sf->list[0]; i < sf->hdr.count; i++) {
  92                         context->put_listent(context,
  93                                              sfe->flags,
  94                                              sfe->nameval,
  95                                              (int)sfe->namelen,
  96                                              (int)sfe->valuelen);
  97                         /*
  98                          * Either search callback finished early or
  99                          * didn't fit it all in the buffer after all.
 100                          */
 101                         if (context->seen_enough)
 102                                 break;
 103                         sfe = XFS_ATTR_SF_NEXTENTRY(sfe);
 104                 }
 105                 trace_xfs_attr_list_sf_all(context);
 106                 return 0;
 107         }
 108
 109         /* do no more for a search callback */
 110         if (context->bufsize == 0)
 111                 return 0;
 112
 113         /*
 114          * It didn't all fit, so we have to sort everything on hashval.
 115          */
 116         sbsize = sf->hdr.count * sizeof(*sbuf);
 117         sbp = sbuf = kmem_alloc(sbsize, KM_SLEEP | KM_NOFS);
 118
 119         /*
 120          * Scan the attribute list for the rest of the entries, storing
 121          * the relevant info from only those that match into a buffer.
 122          */
 123         nsbuf = 0;
 124         for (i = 0, sfe = &sf->list[0]; i < sf->hdr.count; i++) {
 125                 if (unlikely(
 126                     ((char *)sfe < (char *)sf) ||
 127                     ((char *)sfe >= ((char *)sf + dp->i_afp->if_bytes)))) {
 128                         XFS_CORRUPTION_ERROR("xfs_attr_shortform_list",
 129                                              XFS_ERRLEVEL_LOW,
 130                                              context->dp->i_mount, sfe,
 131                                              sizeof(*sfe));
 132                         kmem_free(sbuf);
 133                         return -EFSCORRUPTED;
 134                 }
 135
 136                 sbp->entno = i;
 137                 sbp->hash = xfs_da_hashname(sfe->nameval, sfe->namelen);
 138                 sbp->name = sfe->nameval;
 139                 sbp->namelen = sfe->namelen;
 140                 /* These are bytes, and both on-disk, don't endian-flip */
 141                 sbp->valuelen = sfe->valuelen;
 142                 sbp->flags = sfe->flags;
 143                 sfe = XFS_ATTR_SF_NEXTENTRY(sfe);
 144                 sbp++;
 145                 nsbuf++;
 146         }
 147
 148         /*
 149          * Sort the entries on hash then entno.
 150          */
 151         xfs_sort(sbuf, nsbuf, sizeof(*sbuf), xfs_attr_shortform_compare);
 152
 153         /*
 154          * Re-find our place IN THE SORTED LIST.
 155          */
 156         count = 0;
 157         cursor->initted = 1;
 158         cursor->blkno = 0;
 159         for (sbp = sbuf, i = 0; i < nsbuf; i++, sbp++) {
 160                 if (sbp->hash == cursor->hashval) {
 161                         if (cursor->offset == count) {
 162                                 break;
 163                         }
 164                         count++;
 165                 } else if (sbp->hash > cursor->hashval) {
 166                         break;
 167                 }
 168         }
 169         if (i == nsbuf) {
 170                 kmem_free(sbuf);
 171                 return 0;
 172         }
 173
 174         /*
 175          * Loop putting entries into the user buffer.
 176          */
 177         for ( ; i < nsbuf; i++, sbp++) {
 178                 if (cursor->hashval != sbp->hash) {
 179                         cursor->hashval = sbp->hash;
 180                         cursor->offset = 0;
 181                 }
 182                 context->put_listent(context,
 183                                      sbp->flags,
 184                                      sbp->name,
 185                                      sbp->namelen,
 186                                      sbp->valuelen);
 187                 if (context->seen_enough)
 188                         break;
 189                 cursor->offset++;
 190         }
 191
 192         kmem_free(sbuf);
 193         return 0;
 194 }
 195
 196 /*
 197  * We didn't find the block & hash mentioned in the cursor state, so
 198  * walk down the attr btree looking for the hash.
 199  */
 200 STATIC int
 201 xfs_attr_node_list_lookup(
 202         struct xfs_attr_list_context    *context,
 203         struct attrlist_cursor_kern     *cursor,
 204         struct xfs_buf                  **pbp)
 205 {
 206         struct xfs_da3_icnode_hdr       nodehdr;
 207         struct xfs_da_intnode           *node;
 208         struct xfs_da_node_entry        *btree;
 209         struct xfs_inode                *dp = context->dp;
 210         struct xfs_mount                *mp = dp->i_mount;
 211         struct xfs_trans                *tp = context->tp;
 212         struct xfs_buf                  *bp;
 213         int                             i;
 214         int                             error = 0;
 215         unsigned int                    expected_level = 0;
 216         uint16_t                        magic;
 217
 218         ASSERT(*pbp == NULL);
 219         cursor->blkno = 0;
 220         for (;;) {
 221                 error = xfs_da3_node_read(tp, dp, cursor->blkno, -1, &bp,
 222                                 XFS_ATTR_FORK);
 223                 if (error)
 224                         return error;
 225                 node = bp->b_addr;
 226                 magic = be16_to_cpu(node->hdr.info.magic);
 227                 if (magic == XFS_ATTR_LEAF_MAGIC ||
 228                     magic == XFS_ATTR3_LEAF_MAGIC)
 229                         break;
 230                 if (magic != XFS_DA_NODE_MAGIC &&
 231                     magic != XFS_DA3_NODE_MAGIC) {
 232                         XFS_CORRUPTION_ERROR(__func__, XFS_ERRLEVEL_LOW, mp,
 233                                         node, sizeof(*node));
 234                         goto out_corruptbuf;
 235                 }
 236
 237                 dp->d_ops->node_hdr_from_disk(&nodehdr, node);
 238
 239                 /* Tree taller than we can handle; bail out! */
 240                 if (nodehdr.level >= XFS_DA_NODE_MAXDEPTH)
 241                         goto out_corruptbuf;
 242
 243                 /* Check the level from the root node. */
 244                 if (cursor->blkno == 0)
 245                         expected_level = nodehdr.level - 1;
 246                 else if (expected_level != nodehdr.level)
 247                         goto out_corruptbuf;
 248                 else
 249                         expected_level--;
 250
 251                 btree = dp->d_ops->node_tree_p(node);
 252                 for (i = 0; i < nodehdr.count; btree++, i++) {
 253                         if (cursor->hashval <= be32_to_cpu(btree->hashval)) {
 254                                 cursor->blkno = be32_to_cpu(btree->before);
 255                                 trace_xfs_attr_list_node_descend(context,
 256                                                 btree);
 257                                 break;
 258                         }
 259                 }
 260                 xfs_trans_brelse(tp, bp);
 261
 262                 if (i == nodehdr.count)
 263                         return 0;
 264
 265                 /* We can't point back to the root. */
 266                 if (cursor->blkno == 0)
 267                         return -EFSCORRUPTED;
 268         }
 269
 270         if (expected_level != 0)
 271                 goto out_corruptbuf;
 272
 273         *pbp = bp;
 274         return 0;
 275
 276 out_corruptbuf:
 277         xfs_trans_brelse(tp, bp);
 278         return -EFSCORRUPTED;
 279 }
 280
 281 STATIC int
 282 xfs_attr_node_list(
 283         struct xfs_attr_list_context    *context)
 284 {
 285         struct xfs_attr3_icleaf_hdr     leafhdr;
 286         struct attrlist_cursor_kern     *cursor;
 287         struct xfs_attr_leafblock       *leaf;
 288         struct xfs_da_intnode           *node;
 289         struct xfs_buf                  *bp;
 290         struct xfs_inode                *dp = context->dp;
 291         struct xfs_mount                *mp = dp->i_mount;
 292         int                             error;
 293
 294         trace_xfs_attr_node_list(context);
 295
 296         cursor = context->cursor;
 297         cursor->initted = 1;
 298
 299         /*
 300          * Do all sorts of validation on the passed-in cursor structure.
 301          * If anything is amiss, ignore the cursor and look up the hashval
 302          * starting from the btree root.
 303          */
 304         bp = NULL;
 305         if (cursor->blkno > 0) {
 306                 error = xfs_da3_node_read(context->tp, dp, cursor->blkno, -1,
 307                                               &bp, XFS_ATTR_FORK);
 308                 if ((error != 0) && (error != -EFSCORRUPTED))
 309                         return error;
 310                 if (bp) {
 311                         struct xfs_attr_leaf_entry *entries;
 312
 313                         node = bp->b_addr;
 314                         switch (be16_to_cpu(node->hdr.info.magic)) {
 315                         case XFS_DA_NODE_MAGIC:
 316                         case XFS_DA3_NODE_MAGIC:
 317                                 trace_xfs_attr_list_wrong_blk(context);
 318                                 xfs_trans_brelse(context->tp, bp);
 319                                 bp = NULL;
 320                                 break;
 321                         case XFS_ATTR_LEAF_MAGIC:
 322                         case XFS_ATTR3_LEAF_MAGIC:
 323                                 leaf = bp->b_addr;
 324                                 xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo,
 325                                                              &leafhdr, leaf);
 326                                 entries = xfs_attr3_leaf_entryp(leaf);
 327                                 if (cursor->hashval > be32_to_cpu(
 328                                                 entries[leafhdr.count - 1].hashval)) {
 329                                         trace_xfs_attr_list_wrong_blk(context);
 330                                         xfs_trans_brelse(context->tp, bp);
 331                                         bp = NULL;
 332                                 } else if (cursor->hashval <= be32_to_cpu(
 333                                                 entries[0].hashval)) {
 334                                         trace_xfs_attr_list_wrong_blk(context);
 335                                         xfs_trans_brelse(context->tp, bp);
 336                                         bp = NULL;
 337                                 }
 338                                 break;
 339                         default:
 340                                 trace_xfs_attr_list_wrong_blk(context);
 341                                 xfs_trans_brelse(context->tp, bp);
 342                                 bp = NULL;
 343                         }
 344                 }
 345         }
 346
 347         /*
 348          * We did not find what we expected given the cursor's contents,
 349          * so we start from the top and work down based on the hash value.
 350          * Note that start of node block is same as start of leaf block.
 351          */
 352         if (bp == NULL) {
 353                 error = xfs_attr_node_list_lookup(context, cursor, &bp);
 354                 if (error || !bp)
 355                         return error;
 356         }
 357         ASSERT(bp != NULL);
 358
 359         /*
 360          * Roll upward through the blocks, processing each leaf block in
 361          * order.  As long as there is space in the result buffer, keep
 362          * adding the information.
 363          */
 364         for (;;) {
 365                 leaf = bp->b_addr;
 366                 xfs_attr3_leaf_list_int(bp, context);
 367                 xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
 368                 if (context->seen_enough || leafhdr.forw == 0)
 369                         break;
 370                 cursor->blkno = leafhdr.forw;
 371                 xfs_trans_brelse(context->tp, bp);
 372                 error = xfs_attr3_leaf_read(context->tp, dp, cursor->blkno, -1, &bp);
 373                 if (error)
 374                         return error;
 375         }
 376         xfs_trans_brelse(context->tp, bp);
 377         return 0;
 378 }
 379
 380 /*
 381  * Copy out attribute list entries for attr_list(), for leaf attribute lists.
 382  */
 383 void
 384 xfs_attr3_leaf_list_int(
 385         struct xfs_buf                  *bp,
 386         struct xfs_attr_list_context    *context)
 387 {
 388         struct attrlist_cursor_kern     *cursor;
 389         struct xfs_attr_leafblock       *leaf;
 390         struct xfs_attr3_icleaf_hdr     ichdr;
 391         struct xfs_attr_leaf_entry      *entries;
 392         struct xfs_attr_leaf_entry      *entry;
 393         int                             i;
 394         struct xfs_mount                *mp = context->dp->i_mount;
 395
 396         trace_xfs_attr_list_leaf(context);
 397
 398         leaf = bp->b_addr;
 399         xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &ichdr, leaf);
 400         entries = xfs_attr3_leaf_entryp(leaf);
 401
 402         cursor = context->cursor;
 403         cursor->initted = 1;
 404
 405         /*
 406          * Re-find our place in the leaf block if this is a new syscall.
 407          */
 408         if (context->resynch) {
 409                 entry = &entries[0];
 410                 for (i = 0; i < ichdr.count; entry++, i++) {
 411                         if (be32_to_cpu(entry->hashval) == cursor->hashval) {
 412                                 if (cursor->offset == context->dupcnt) {
 413                                         context->dupcnt = 0;
 414                                         break;
 415                                 }
 416                                 context->dupcnt++;
 417                         } else if (be32_to_cpu(entry->hashval) >
 418                                         cursor->hashval) {
 419                                 context->dupcnt = 0;
 420                                 break;
 421                         }
 422                 }
 423                 if (i == ichdr.count) {
 424                         trace_xfs_attr_list_notfound(context);
 425                         return;
 426                 }
 427         } else {
 428                 entry = &entries[0];
 429                 i = 0;
 430         }
 431         context->resynch = 0;
 432
 433         /*
 434          * We have found our place, start copying out the new attributes.
 435          */
 436         for (; i < ichdr.count; entry++, i++) {
 437                 char *name;
 438                 int namelen, valuelen;
 439
 440                 if (be32_to_cpu(entry->hashval) != cursor->hashval) {
 441                         cursor->hashval = be32_to_cpu(entry->hashval);
 442                         cursor->offset = 0;
 443                 }
 444
 445                 if ((entry->flags & XFS_ATTR_INCOMPLETE) &&
 446                     !(context->flags & ATTR_INCOMPLETE))
 447                         continue;               /* skip incomplete entries */
 448
 449                 if (entry->flags & XFS_ATTR_LOCAL) {
 450                         xfs_attr_leaf_name_local_t *name_loc;
 451
 452                         name_loc = xfs_attr3_leaf_name_local(leaf, i);
 453                         name = name_loc->nameval;
 454                         namelen = name_loc->namelen;
 455                         valuelen = be16_to_cpu(name_loc->valuelen);
 456                 } else {
 457                         xfs_attr_leaf_name_remote_t *name_rmt;
 458
 459                         name_rmt = xfs_attr3_leaf_name_remote(leaf, i);
 460                         name = name_rmt->name;
 461                         namelen = name_rmt->namelen;
 462                         valuelen = be32_to_cpu(name_rmt->valuelen);
 463                 }
 464
 465                 context->put_listent(context, entry->flags,
 466                                               name, namelen, valuelen);
 467                 if (context->seen_enough)
 468                         break;
 469                 cursor->offset++;
 470         }
 471         trace_xfs_attr_list_leaf_end(context);
 472         return;
 473 }
 474
 475 /*
 476  * Copy out attribute entries for attr_list(), for leaf attribute lists.
 477  */
 478 STATIC int
 479 xfs_attr_leaf_list(xfs_attr_list_context_t *context)
 480 {
 481         int error;
 482         struct xfs_buf *bp;
 483
 484         trace_xfs_attr_leaf_list(context);
 485
 486         context->cursor->blkno = 0;
 487         error = xfs_attr3_leaf_read(context->tp, context->dp, 0, -1, &bp);
 488         if (error)
 489                 return error;
 490
 491         xfs_attr3_leaf_list_int(bp, context);
 492         xfs_trans_brelse(context->tp, bp);
 493         return 0;
 494 }
 495
 496 int
 497 xfs_attr_list_int_ilocked(
 498         struct xfs_attr_list_context    *context)
 499 {
 500         struct xfs_inode                *dp = context->dp;
 501
 502         ASSERT(xfs_isilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL));
 503
 504         /*
 505          * Decide on what work routines to call based on the inode size.
 506          */
 507         if (!xfs_inode_hasattr(dp))
 508                 return 0;
 509         else if (dp->i_d.di_aformat == XFS_DINODE_FMT_LOCAL)
 510                 return xfs_attr_shortform_list(context);
 511         else if (xfs_bmap_one_block(dp, XFS_ATTR_FORK))
 512                 return xfs_attr_leaf_list(context);
 513         return xfs_attr_node_list(context);
 514 }
 515
 516 int
 517 xfs_attr_list_int(
 518         xfs_attr_list_context_t *context)
 519 {
 520         int error;
 521         xfs_inode_t *dp = context->dp;
 522         uint            lock_mode;
 523
 524         XFS_STATS_INC(dp->i_mount, xs_attr_list);
 525
 526         if (XFS_FORCED_SHUTDOWN(dp->i_mount))
 527                 return -EIO;
 528
 529         lock_mode = xfs_ilock_attr_map_shared(dp);
 530         error = xfs_attr_list_int_ilocked(context);
 531         xfs_iunlock(dp, lock_mode);
 532         return error;
 533 }
 534
 535 #define ATTR_ENTBASESIZE                /* minimum bytes used by an attr */ \
 536         (((struct attrlist_ent *) 0)->a_name - (char *) 0)
 537 #define ATTR_ENTSIZE(namelen)           /* actual bytes used by an attr */ \
 538         ((ATTR_ENTBASESIZE + (namelen) + 1 + sizeof(uint32_t)-1) \
 539          & ~(sizeof(uint32_t)-1))
 540
 541 /*
 542  * Format an attribute and copy it out to the user's buffer.
 543  * Take care to check values and protect against them changing later,
 544  * we may be reading them directly out of a user buffer.
 545  */
 546 STATIC void
 547 xfs_attr_put_listent(
 548         xfs_attr_list_context_t *context,
 549         int             flags,
 550         unsigned char   *name,
 551         int             namelen,
 552         int             valuelen)
 553 {
 554         struct attrlist *alist = (struct attrlist *)context->alist;
 555         attrlist_ent_t *aep;
 556         int arraytop;
 557
 558         ASSERT(!context->seen_enough);
 559         ASSERT(!(context->flags & ATTR_KERNOVAL));
 560         ASSERT(context->count >= 0);
 561         ASSERT(context->count < (ATTR_MAX_VALUELEN/8));
 562         ASSERT(context->firstu >= sizeof(*alist));
 563         ASSERT(context->firstu <= context->bufsize);
 564
 565         /*
 566          * Only list entries in the right namespace.
 567          */
 568         if (((context->flags & ATTR_SECURE) == 0) !=
 569             ((flags & XFS_ATTR_SECURE) == 0))
 570                 return;
 571         if (((context->flags & ATTR_ROOT) == 0) !=
 572             ((flags & XFS_ATTR_ROOT) == 0))
 573                 return;
 574
 575         arraytop = sizeof(*alist) +
 576                         context->count * sizeof(alist->al_offset[0]);
 577         context->firstu -= ATTR_ENTSIZE(namelen);
 578         if (context->firstu < arraytop) {
 579                 trace_xfs_attr_list_full(context);
 580                 alist->al_more = 1;
 581                 context->seen_enough = 1;
 582                 return;
 583         }
 584
 585         aep = (attrlist_ent_t *)&context->alist[context->firstu];
 586         aep->a_valuelen = valuelen;
 587         memcpy(aep->a_name, name, namelen);
 588         aep->a_name[namelen] = 0;
 589         alist->al_offset[context->count++] = context->firstu;
 590         alist->al_count = context->count;
 591         trace_xfs_attr_list_add(context);
 592         return;
 593 }
 594
 595 /*
 596  * Generate a list of extended attribute names and optionally
 597  * also value lengths.  Positive return value follows the XFS
 598  * convention of being an error, zero or negative return code
 599  * is the length of the buffer returned (negated), indicating
 600  * success.
 601  */
 602 int
 603 xfs_attr_list(
 604         xfs_inode_t     *dp,
 605         char            *buffer,
 606         int             bufsize,
 607         int             flags,
 608         attrlist_cursor_kern_t *cursor)
 609 {
 610         xfs_attr_list_context_t context;
 611         struct attrlist *alist;
 612         int error;
 613
 614         /*
 615          * Validate the cursor.
 616          */
 617         if (cursor->pad1 || cursor->pad2)
 618                 return -EINVAL;
 619         if ((cursor->initted == 0) &&
 620             (cursor->hashval || cursor->blkno || cursor->offset))
 621                 return -EINVAL;
 622
 623         /* Only internal consumers can retrieve incomplete attrs. */
 624         if (flags & ATTR_INCOMPLETE)
 625                 return -EINVAL;
 626
 627         /*
 628          * Check for a properly aligned buffer.
 629          */
 630         if (((long)buffer) & (sizeof(int)-1))
 631                 return -EFAULT;
 632         if (flags & ATTR_KERNOVAL)
 633                 bufsize = 0;
 634
 635         /*
 636          * Initialize the output buffer.
 637          */
 638         memset(&context, 0, sizeof(context));
 639         context.dp = dp;
 640         context.cursor = cursor;
 641         context.resynch = 1;
 642         context.flags = flags;
 643         context.alist = buffer;
 644         context.bufsize = (bufsize & ~(sizeof(int)-1));  /* align */
 645         context.firstu = context.bufsize;
 646         context.put_listent = xfs_attr_put_listent;
 647
 648         alist = (struct attrlist *)context.alist;
 649         alist->al_count = 0;
 650         alist->al_more = 0;
 651         alist->al_offset[0] = context.bufsize;
 652
 653         error = xfs_attr_list_int(&context);
 654         ASSERT(error <= 0);
 655         return error;
 656 }