fs/xfs/scrub/attr.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
   4  * Author: Darrick J. Wong <[email protected]>
   5  */
   6 #include "xfs.h"
   7 #include "xfs_fs.h"
   8 #include "xfs_shared.h"
   9 #include "xfs_format.h"
  10 #include "xfs_trans_resv.h"
  11 #include "xfs_mount.h"
  12 #include "xfs_log_format.h"
  13 #include "xfs_inode.h"
  14 #include "xfs_da_format.h"
  15 #include "xfs_da_btree.h"
  16 #include "xfs_attr.h"
  17 #include "xfs_attr_leaf.h"
  18 #include "xfs_attr_sf.h"
  19 #include "scrub/scrub.h"
  20 #include "scrub/common.h"
  21 #include "scrub/dabtree.h"
  22 #include "scrub/attr.h"
  23
  24 /* Free the buffers linked from the xattr buffer. */
  25 static void
  26 xchk_xattr_buf_cleanup(
  27         void                    *priv)
  28 {
  29         struct xchk_xattr_buf   *ab = priv;
  30
  31         kvfree(ab->freemap);
  32         ab->freemap = NULL;
  33         kvfree(ab->usedmap);
  34         ab->usedmap = NULL;
  35         kvfree(ab->value);
  36         ab->value = NULL;
  37         ab->value_sz = 0;
  38 }
  39
  40 /*
  41  * Allocate the free space bitmap if we're trying harder; there are leaf blocks
  42  * in the attr fork; or we can't tell if there are leaf blocks.
  43  */
  44 static inline bool
  45 xchk_xattr_want_freemap(
  46         struct xfs_scrub        *sc)
  47 {
  48         struct xfs_ifork        *ifp;
  49
  50         if (sc->flags & XCHK_TRY_HARDER)
  51                 return true;
  52
  53         if (!sc->ip)
  54                 return true;
  55
  56         ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);
  57         if (!ifp)
  58                 return false;
  59
  60         return xfs_ifork_has_extents(ifp);
  61 }
  62
  63 /*
  64  * Allocate enough memory to hold an attr value and attr block bitmaps,
  65  * reallocating the buffer if necessary.  Buffer contents are not preserved
  66  * across a reallocation.
  67  */
  68 static int
  69 xchk_setup_xattr_buf(
  70         struct xfs_scrub        *sc,
  71         size_t                  value_size)
  72 {
  73         size_t                  bmp_sz;
  74         struct xchk_xattr_buf   *ab = sc->buf;
  75         void                    *new_val;
  76
  77         bmp_sz = sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
  78
  79         if (ab)
  80                 goto resize_value;
  81
  82         ab = kvzalloc(sizeof(struct xchk_xattr_buf), XCHK_GFP_FLAGS);
  83         if (!ab)
  84                 return -ENOMEM;
  85         sc->buf = ab;
  86         sc->buf_cleanup = xchk_xattr_buf_cleanup;
  87
  88         ab->usedmap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
  89         if (!ab->usedmap)
  90                 return -ENOMEM;
  91
  92         if (xchk_xattr_want_freemap(sc)) {
  93                 ab->freemap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
  94                 if (!ab->freemap)
  95                         return -ENOMEM;
  96         }
  97
  98 resize_value:
  99         if (ab->value_sz >= value_size)
 100                 return 0;
 101
 102         if (ab->value) {
 103                 kvfree(ab->value);
 104                 ab->value = NULL;
 105                 ab->value_sz = 0;
 106         }
 107
 108         new_val = kvmalloc(value_size, XCHK_GFP_FLAGS);
 109         if (!new_val)
 110                 return -ENOMEM;
 111
 112         ab->value = new_val;
 113         ab->value_sz = value_size;
 114         return 0;
 115 }
 116
 117 /* Set us up to scrub an inode's extended attributes. */
 118 int
 119 xchk_setup_xattr(
 120         struct xfs_scrub        *sc)
 121 {
 122         int                     error;
 123
 124         /*
 125          * We failed to get memory while checking attrs, so this time try to
 126          * get all the memory we're ever going to need.  Allocate the buffer
 127          * without the inode lock held, which means we can sleep.
 128          */
 129         if (sc->flags & XCHK_TRY_HARDER) {
 130                 error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX);
 131                 if (error)
 132                         return error;
 133         }
 134
 135         return xchk_setup_inode_contents(sc, 0);
 136 }
 137
 138 /* Extended Attributes */
 139
 140 struct xchk_xattr {
 141         struct xfs_attr_list_context    context;
 142         struct xfs_scrub                *sc;
 143 };
 144
 145 /*
 146  * Check that an extended attribute key can be looked up by hash.
 147  *
 148  * We use the XFS attribute list iterator (i.e. xfs_attr_list_ilocked)
 149  * to call this function for every attribute key in an inode.  Once
 150  * we're here, we load the attribute value to see if any errors happen,
 151  * or if we get more or less data than we expected.
 152  */
 153 static void
 154 xchk_xattr_listent(
 155         struct xfs_attr_list_context    *context,
 156         int                             flags,
 157         unsigned char                   *name,
 158         int                             namelen,
 159         int                             valuelen)
 160 {
 161         struct xfs_da_args              args = {
 162                 .op_flags               = XFS_DA_OP_NOTIME,
 163                 .attr_filter            = flags & XFS_ATTR_NSP_ONDISK_MASK,
 164                 .geo                    = context->dp->i_mount->m_attr_geo,
 165                 .whichfork              = XFS_ATTR_FORK,
 166                 .dp                     = context->dp,
 167                 .name                   = name,
 168                 .namelen                = namelen,
 169                 .hashval                = xfs_da_hashname(name, namelen),
 170                 .trans                  = context->tp,
 171                 .valuelen               = valuelen,
 172         };
 173         struct xchk_xattr_buf           *ab;
 174         struct xchk_xattr               *sx;
 175         int                             error = 0;
 176
 177         sx = container_of(context, struct xchk_xattr, context);
 178         ab = sx->sc->buf;
 179
 180         if (xchk_should_terminate(sx->sc, &error)) {
 181                 context->seen_enough = error;
 182                 return;
 183         }
 184
 185         if (flags & XFS_ATTR_INCOMPLETE) {
 186                 /* Incomplete attr key, just mark the inode for preening. */
 187                 xchk_ino_set_preen(sx->sc, context->dp->i_ino);
 188                 return;
 189         }
 190
 191         /* Only one namespace bit allowed. */
 192         if (hweight32(flags & XFS_ATTR_NSP_ONDISK_MASK) > 1) {
 193                 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
 194                 goto fail_xref;
 195         }
 196
 197         /* Does this name make sense? */
 198         if (!xfs_attr_namecheck(name, namelen)) {
 199                 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
 200                 goto fail_xref;
 201         }
 202
 203         /*
 204          * Local xattr values are stored in the attr leaf block, so we don't
 205          * need to retrieve the value from a remote block to detect corruption
 206          * problems.
 207          */
 208         if (flags & XFS_ATTR_LOCAL)
 209                 goto fail_xref;
 210
 211         /*
 212          * Try to allocate enough memory to extrat the attr value.  If that
 213          * doesn't work, we overload the seen_enough variable to convey
 214          * the error message back to the main scrub function.
 215          */
 216         error = xchk_setup_xattr_buf(sx->sc, valuelen);
 217         if (error == -ENOMEM)
 218                 error = -EDEADLOCK;
 219         if (error) {
 220                 context->seen_enough = error;
 221                 return;
 222         }
 223
 224         args.value = ab->value;
 225
 226         error = xfs_attr_get_ilocked(&args);
 227         /* ENODATA means the hash lookup failed and the attr is bad */
 228         if (error == -ENODATA)
 229                 error = -EFSCORRUPTED;
 230         if (!xchk_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
 231                         &error))
 232                 goto fail_xref;
 233         if (args.valuelen != valuelen)
 234                 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
 235                                              args.blkno);
 236 fail_xref:
 237         if (sx->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 238                 context->seen_enough = 1;
 239         return;
 240 }
 241
 242 /*
 243  * Mark a range [start, start+len) in this map.  Returns true if the
 244  * region was free, and false if there's a conflict or a problem.
 245  *
 246  * Within a char, the lowest bit of the char represents the byte with
 247  * the smallest address
 248  */
 249 STATIC bool
 250 xchk_xattr_set_map(
 251         struct xfs_scrub        *sc,
 252         unsigned long           *map,
 253         unsigned int            start,
 254         unsigned int            len)
 255 {
 256         unsigned int            mapsize = sc->mp->m_attr_geo->blksize;
 257         bool                    ret = true;
 258
 259         if (start >= mapsize)
 260                 return false;
 261         if (start + len > mapsize) {
 262                 len = mapsize - start;
 263                 ret = false;
 264         }
 265
 266         if (find_next_bit(map, mapsize, start) < start + len)
 267                 ret = false;
 268         bitmap_set(map, start, len);
 269
 270         return ret;
 271 }
 272
 273 /*
 274  * Check the leaf freemap from the usage bitmap.  Returns false if the
 275  * attr freemap has problems or points to used space.
 276  */
 277 STATIC bool
 278 xchk_xattr_check_freemap(
 279         struct xfs_scrub                *sc,
 280         struct xfs_attr3_icleaf_hdr     *leafhdr)
 281 {
 282         struct xchk_xattr_buf           *ab = sc->buf;
 283         unsigned int                    mapsize = sc->mp->m_attr_geo->blksize;
 284         int                             i;
 285
 286         /* Construct bitmap of freemap contents. */
 287         bitmap_zero(ab->freemap, mapsize);
 288         for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
 289                 if (!xchk_xattr_set_map(sc, ab->freemap,
 290                                 leafhdr->freemap[i].base,
 291                                 leafhdr->freemap[i].size))
 292                         return false;
 293         }
 294
 295         /* Look for bits that are set in freemap and are marked in use. */
 296         return !bitmap_intersects(ab->freemap, ab->usedmap, mapsize);
 297 }
 298
 299 /*
 300  * Check this leaf entry's relations to everything else.
 301  * Returns the number of bytes used for the name/value data.
 302  */
 303 STATIC void
 304 xchk_xattr_entry(
 305         struct xchk_da_btree            *ds,
 306         int                             level,
 307         char                            *buf_end,
 308         struct xfs_attr_leafblock       *leaf,
 309         struct xfs_attr3_icleaf_hdr     *leafhdr,
 310         struct xfs_attr_leaf_entry      *ent,
 311         int                             idx,
 312         unsigned int                    *usedbytes,
 313         __u32                           *last_hashval)
 314 {
 315         struct xfs_mount                *mp = ds->state->mp;
 316         struct xchk_xattr_buf           *ab = ds->sc->buf;
 317         char                            *name_end;
 318         struct xfs_attr_leaf_name_local *lentry;
 319         struct xfs_attr_leaf_name_remote *rentry;
 320         unsigned int                    nameidx;
 321         unsigned int                    namesize;
 322
 323         if (ent->pad2 != 0)
 324                 xchk_da_set_corrupt(ds, level);
 325
 326         /* Hash values in order? */
 327         if (be32_to_cpu(ent->hashval) < *last_hashval)
 328                 xchk_da_set_corrupt(ds, level);
 329         *last_hashval = be32_to_cpu(ent->hashval);
 330
 331         nameidx = be16_to_cpu(ent->nameidx);
 332         if (nameidx < leafhdr->firstused ||
 333             nameidx >= mp->m_attr_geo->blksize) {
 334                 xchk_da_set_corrupt(ds, level);
 335                 return;
 336         }
 337
 338         /* Check the name information. */
 339         if (ent->flags & XFS_ATTR_LOCAL) {
 340                 lentry = xfs_attr3_leaf_name_local(leaf, idx);
 341                 namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
 342                                 be16_to_cpu(lentry->valuelen));
 343                 name_end = (char *)lentry + namesize;
 344                 if (lentry->namelen == 0)
 345                         xchk_da_set_corrupt(ds, level);
 346         } else {
 347                 rentry = xfs_attr3_leaf_name_remote(leaf, idx);
 348                 namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
 349                 name_end = (char *)rentry + namesize;
 350                 if (rentry->namelen == 0 || rentry->valueblk == 0)
 351                         xchk_da_set_corrupt(ds, level);
 352         }
 353         if (name_end > buf_end)
 354                 xchk_da_set_corrupt(ds, level);
 355
 356         if (!xchk_xattr_set_map(ds->sc, ab->usedmap, nameidx, namesize))
 357                 xchk_da_set_corrupt(ds, level);
 358         if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
 359                 *usedbytes += namesize;
 360 }
 361
 362 /* Scrub an attribute leaf. */
 363 STATIC int
 364 xchk_xattr_block(
 365         struct xchk_da_btree            *ds,
 366         int                             level)
 367 {
 368         struct xfs_attr3_icleaf_hdr     leafhdr;
 369         struct xfs_mount                *mp = ds->state->mp;
 370         struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
 371         struct xfs_buf                  *bp = blk->bp;
 372         xfs_dablk_t                     *last_checked = ds->private;
 373         struct xfs_attr_leafblock       *leaf = bp->b_addr;
 374         struct xfs_attr_leaf_entry      *ent;
 375         struct xfs_attr_leaf_entry      *entries;
 376         struct xchk_xattr_buf           *ab = ds->sc->buf;
 377         char                            *buf_end;
 378         size_t                          off;
 379         __u32                           last_hashval = 0;
 380         unsigned int                    usedbytes = 0;
 381         unsigned int                    hdrsize;
 382         int                             i;
 383
 384         if (*last_checked == blk->blkno)
 385                 return 0;
 386
 387         *last_checked = blk->blkno;
 388         bitmap_zero(ab->usedmap, mp->m_attr_geo->blksize);
 389
 390         /* Check all the padding. */
 391         if (xfs_has_crc(ds->sc->mp)) {
 392                 struct xfs_attr3_leafblock      *leaf3 = bp->b_addr;
 393
 394                 if (leaf3->hdr.pad1 != 0 || leaf3->hdr.pad2 != 0 ||
 395                     leaf3->hdr.info.hdr.pad != 0)
 396                         xchk_da_set_corrupt(ds, level);
 397         } else {
 398                 if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
 399                         xchk_da_set_corrupt(ds, level);
 400         }
 401
 402         /* Check the leaf header */
 403         xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
 404         hdrsize = xfs_attr3_leaf_hdr_size(leaf);
 405
 406         if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
 407                 xchk_da_set_corrupt(ds, level);
 408         if (leafhdr.firstused > mp->m_attr_geo->blksize)
 409                 xchk_da_set_corrupt(ds, level);
 410         if (leafhdr.firstused < hdrsize)
 411                 xchk_da_set_corrupt(ds, level);
 412         if (!xchk_xattr_set_map(ds->sc, ab->usedmap, 0, hdrsize))
 413                 xchk_da_set_corrupt(ds, level);
 414
 415         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 416                 goto out;
 417
 418         entries = xfs_attr3_leaf_entryp(leaf);
 419         if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
 420                 xchk_da_set_corrupt(ds, level);
 421
 422         buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
 423         for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
 424                 /* Mark the leaf entry itself. */
 425                 off = (char *)ent - (char *)leaf;
 426                 if (!xchk_xattr_set_map(ds->sc, ab->usedmap, off,
 427                                 sizeof(xfs_attr_leaf_entry_t))) {
 428                         xchk_da_set_corrupt(ds, level);
 429                         goto out;
 430                 }
 431
 432                 /* Check the entry and nameval. */
 433                 xchk_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
 434                                 ent, i, &usedbytes, &last_hashval);
 435
 436                 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 437                         goto out;
 438         }
 439
 440         if (!xchk_xattr_check_freemap(ds->sc, &leafhdr))
 441                 xchk_da_set_corrupt(ds, level);
 442
 443         if (leafhdr.usedbytes != usedbytes)
 444                 xchk_da_set_corrupt(ds, level);
 445
 446 out:
 447         return 0;
 448 }
 449
 450 /* Scrub a attribute btree record. */
 451 STATIC int
 452 xchk_xattr_rec(
 453         struct xchk_da_btree            *ds,
 454         int                             level)
 455 {
 456         struct xfs_mount                *mp = ds->state->mp;
 457         struct xfs_da_state_blk         *blk = &ds->state->path.blk[level];
 458         struct xfs_attr_leaf_name_local *lentry;
 459         struct xfs_attr_leaf_name_remote        *rentry;
 460         struct xfs_buf                  *bp;
 461         struct xfs_attr_leaf_entry      *ent;
 462         xfs_dahash_t                    calc_hash;
 463         xfs_dahash_t                    hash;
 464         int                             nameidx;
 465         int                             hdrsize;
 466         unsigned int                    badflags;
 467         int                             error;
 468
 469         ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
 470
 471         ent = xfs_attr3_leaf_entryp(blk->bp->b_addr) + blk->index;
 472
 473         /* Check the whole block, if necessary. */
 474         error = xchk_xattr_block(ds, level);
 475         if (error)
 476                 goto out;
 477         if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 478                 goto out;
 479
 480         /* Check the hash of the entry. */
 481         error = xchk_da_btree_hash(ds, level, &ent->hashval);
 482         if (error)
 483                 goto out;
 484
 485         /* Find the attr entry's location. */
 486         bp = blk->bp;
 487         hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
 488         nameidx = be16_to_cpu(ent->nameidx);
 489         if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
 490                 xchk_da_set_corrupt(ds, level);
 491                 goto out;
 492         }
 493
 494         /* Retrieve the entry and check it. */
 495         hash = be32_to_cpu(ent->hashval);
 496         badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
 497                         XFS_ATTR_INCOMPLETE);
 498         if ((ent->flags & badflags) != 0)
 499                 xchk_da_set_corrupt(ds, level);
 500         if (ent->flags & XFS_ATTR_LOCAL) {
 501                 lentry = (struct xfs_attr_leaf_name_local *)
 502                                 (((char *)bp->b_addr) + nameidx);
 503                 if (lentry->namelen <= 0) {
 504                         xchk_da_set_corrupt(ds, level);
 505                         goto out;
 506                 }
 507                 calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
 508         } else {
 509                 rentry = (struct xfs_attr_leaf_name_remote *)
 510                                 (((char *)bp->b_addr) + nameidx);
 511                 if (rentry->namelen <= 0) {
 512                         xchk_da_set_corrupt(ds, level);
 513                         goto out;
 514                 }
 515                 calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
 516         }
 517         if (calc_hash != hash)
 518                 xchk_da_set_corrupt(ds, level);
 519
 520 out:
 521         return error;
 522 }
 523
 524 /* Check space usage of shortform attrs. */
 525 STATIC int
 526 xchk_xattr_check_sf(
 527         struct xfs_scrub                *sc)
 528 {
 529         struct xchk_xattr_buf           *ab = sc->buf;
 530         struct xfs_attr_shortform       *sf;
 531         struct xfs_attr_sf_entry        *sfe;
 532         struct xfs_attr_sf_entry        *next;
 533         struct xfs_ifork                *ifp;
 534         unsigned char                   *end;
 535         int                             i;
 536         int                             error = 0;
 537
 538         ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);
 539
 540         bitmap_zero(ab->usedmap, ifp->if_bytes);
 541         sf = (struct xfs_attr_shortform *)sc->ip->i_af.if_u1.if_data;
 542         end = (unsigned char *)ifp->if_u1.if_data + ifp->if_bytes;
 543         xchk_xattr_set_map(sc, ab->usedmap, 0, sizeof(sf->hdr));
 544
 545         sfe = &sf->list[0];
 546         if ((unsigned char *)sfe > end) {
 547                 xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
 548                 return 0;
 549         }
 550
 551         for (i = 0; i < sf->hdr.count; i++) {
 552                 unsigned char           *name = sfe->nameval;
 553                 unsigned char           *value = &sfe->nameval[sfe->namelen];
 554
 555                 if (xchk_should_terminate(sc, &error))
 556                         return error;
 557
 558                 next = xfs_attr_sf_nextentry(sfe);
 559                 if ((unsigned char *)next > end) {
 560                         xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
 561                         break;
 562                 }
 563
 564                 if (!xchk_xattr_set_map(sc, ab->usedmap,
 565                                 (char *)sfe - (char *)sf,
 566                                 sizeof(struct xfs_attr_sf_entry))) {
 567                         xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
 568                         break;
 569                 }
 570
 571                 if (!xchk_xattr_set_map(sc, ab->usedmap,
 572                                 (char *)name - (char *)sf,
 573                                 sfe->namelen)) {
 574                         xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
 575                         break;
 576                 }
 577
 578                 if (!xchk_xattr_set_map(sc, ab->usedmap,
 579                                 (char *)value - (char *)sf,
 580                                 sfe->valuelen)) {
 581                         xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
 582                         break;
 583                 }
 584
 585                 sfe = next;
 586         }
 587
 588         return 0;
 589 }
 590
 591 /* Scrub the extended attribute metadata. */
 592 int
 593 xchk_xattr(
 594         struct xfs_scrub                *sc)
 595 {
 596         struct xchk_xattr               sx = {
 597                 .sc                     = sc,
 598                 .context                = {
 599                         .dp             = sc->ip,
 600                         .tp             = sc->tp,
 601                         .resynch        = 1,
 602                         .put_listent    = xchk_xattr_listent,
 603                         .allow_incomplete = true,
 604                 },
 605         };
 606         xfs_dablk_t                     last_checked = -1U;
 607         int                             error = 0;
 608
 609         if (!xfs_inode_hasattr(sc->ip))
 610                 return -ENOENT;
 611
 612         /* Allocate memory for xattr checking. */
 613         error = xchk_setup_xattr_buf(sc, 0);
 614         if (error == -ENOMEM)
 615                 return -EDEADLOCK;
 616         if (error)
 617                 return error;
 618
 619         /* Check the physical structure of the xattr. */
 620         if (sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL)
 621                 error = xchk_xattr_check_sf(sc);
 622         else
 623                 error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
 624                                 &last_checked);
 625         if (error)
 626                 return error;
 627
 628         if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 629                 return 0;
 630
 631         /*
 632          * Look up every xattr in this file by name and hash.
 633          *
 634          * Use the backend implementation of xfs_attr_list to call
 635          * xchk_xattr_listent on every attribute key in this inode.
 636          * In other words, we use the same iterator/callback mechanism
 637          * that listattr uses to scrub extended attributes, though in our
 638          * _listent function, we check the value of the attribute.
 639          *
 640          * The VFS only locks i_rwsem when modifying attrs, so keep all
 641          * three locks held because that's the only way to ensure we're
 642          * the only thread poking into the da btree.  We traverse the da
 643          * btree while holding a leaf buffer locked for the xattr name
 644          * iteration, which doesn't really follow the usual buffer
 645          * locking order.
 646          */
 647         error = xfs_attr_list_ilocked(&sx.context);
 648         if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
 649                 return error;
 650
 651         /* Did our listent function try to return any errors? */
 652         if (sx.context.seen_enough < 0)
 653                 return sx.context.seen_enough;
 654
 655         return 0;
 656 }