xref: /linux/fs/xfs/scrub/attr.c (revision 6f7e6393d1ce636bb7ec77a7fe7b77458fddf701)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright (C) 2017-2023 Oracle.  All Rights Reserved.
4  * Author: Darrick J. Wong <djwong@kernel.org>
5  */
6 #include "xfs_platform.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_trans.h"
14 #include "xfs_inode.h"
15 #include "xfs_da_format.h"
16 #include "xfs_da_btree.h"
17 #include "xfs_attr.h"
18 #include "xfs_attr_leaf.h"
19 #include "xfs_attr_sf.h"
20 #include "xfs_parent.h"
21 #include "scrub/scrub.h"
22 #include "scrub/common.h"
23 #include "scrub/dabtree.h"
24 #include "scrub/attr.h"
25 #include "scrub/listxattr.h"
26 #include "scrub/repair.h"
27 
28 /* Free the buffers linked from the xattr buffer. */
29 static void
30 xchk_xattr_buf_cleanup(
31 	void			*priv)
32 {
33 	struct xchk_xattr_buf	*ab = priv;
34 
35 	kvfree(ab->freemap);
36 	ab->freemap = NULL;
37 	kvfree(ab->usedmap);
38 	ab->usedmap = NULL;
39 	kvfree(ab->value);
40 	ab->value = NULL;
41 	ab->value_sz = 0;
42 	kvfree(ab->name);
43 	ab->name = NULL;
44 }
45 
46 /*
47  * Allocate the free space bitmap if we're trying harder; there are leaf blocks
48  * in the attr fork; or we can't tell if there are leaf blocks.
49  */
50 static inline bool
51 xchk_xattr_want_freemap(
52 	struct xfs_scrub	*sc)
53 {
54 	struct xfs_ifork	*ifp;
55 
56 	if (sc->flags & XCHK_TRY_HARDER)
57 		return true;
58 
59 	if (!sc->ip)
60 		return true;
61 
62 	ifp = xfs_ifork_ptr(sc->ip, XFS_ATTR_FORK);
63 	if (!ifp)
64 		return false;
65 
66 	return xfs_ifork_has_extents(ifp);
67 }
68 
69 /*
70  * Allocate enough memory to hold an attr value and attr block bitmaps,
71  * reallocating the buffer if necessary.  Buffer contents are not preserved
72  * across a reallocation.
73  */
74 int
75 xchk_setup_xattr_buf(
76 	struct xfs_scrub	*sc,
77 	size_t			value_size)
78 {
79 	size_t			bmp_sz;
80 	struct xchk_xattr_buf	*ab = sc->buf;
81 	void			*new_val;
82 
83 	bmp_sz = sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
84 
85 	if (ab)
86 		goto resize_value;
87 
88 	ab = kvzalloc(sizeof(struct xchk_xattr_buf), XCHK_GFP_FLAGS);
89 	if (!ab)
90 		return -ENOMEM;
91 	sc->buf = ab;
92 	sc->buf_cleanup = xchk_xattr_buf_cleanup;
93 
94 	ab->usedmap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
95 	if (!ab->usedmap)
96 		return -ENOMEM;
97 
98 	if (xchk_xattr_want_freemap(sc)) {
99 		ab->freemap = kvmalloc(bmp_sz, XCHK_GFP_FLAGS);
100 		if (!ab->freemap)
101 			return -ENOMEM;
102 	}
103 
104 	if (xchk_could_repair(sc)) {
105 		ab->name = kvmalloc(XATTR_NAME_MAX + 1, XCHK_GFP_FLAGS);
106 		if (!ab->name)
107 			return -ENOMEM;
108 	}
109 
110 resize_value:
111 	if (ab->value_sz >= value_size)
112 		return 0;
113 
114 	if (ab->value) {
115 		kvfree(ab->value);
116 		ab->value = NULL;
117 		ab->value_sz = 0;
118 	}
119 
120 	new_val = kvmalloc(value_size, XCHK_GFP_FLAGS);
121 	if (!new_val)
122 		return -ENOMEM;
123 
124 	ab->value = new_val;
125 	ab->value_sz = value_size;
126 	return 0;
127 }
128 
129 /* Set us up to scrub an inode's extended attributes. */
130 int
131 xchk_setup_xattr(
132 	struct xfs_scrub	*sc)
133 {
134 	int			error;
135 
136 	if (xchk_could_repair(sc)) {
137 		error = xrep_setup_xattr(sc);
138 		if (error)
139 			return error;
140 	}
141 
142 	/*
143 	 * We failed to get memory while checking attrs, so this time try to
144 	 * get all the memory we're ever going to need.  Allocate the buffer
145 	 * without the inode lock held, which means we can sleep.
146 	 */
147 	if (sc->flags & XCHK_TRY_HARDER) {
148 		error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX);
149 		if (error)
150 			return error;
151 	}
152 
153 	return xchk_setup_inode_contents(sc, 0);
154 }
155 
156 /* Extended Attributes */
157 
158 /*
159  * Check that an extended attribute key can be looked up by hash.
160  *
161  * We use the extended attribute walk helper to call this function for every
162  * attribute key in an inode.  Once we're here, we load the attribute value to
163  * see if any errors happen, or if we get more or less data than we expected.
164  */
165 static int
166 xchk_xattr_actor(
167 	struct xfs_scrub	*sc,
168 	struct xfs_inode	*ip,
169 	unsigned int		attr_flags,
170 	const unsigned char	*name,
171 	unsigned int		namelen,
172 	const void		*value,
173 	unsigned int		valuelen,
174 	void			*priv)
175 {
176 	struct xfs_da_args		args = {
177 		.attr_filter		= attr_flags & XFS_ATTR_NSP_ONDISK_MASK,
178 		.geo			= sc->mp->m_attr_geo,
179 		.whichfork		= XFS_ATTR_FORK,
180 		.dp			= ip,
181 		.name			= name,
182 		.namelen		= namelen,
183 		.trans			= sc->tp,
184 		.valuelen		= valuelen,
185 		.owner			= ip->i_ino,
186 	};
187 	struct xchk_xattr_buf		*ab;
188 	int				error = 0;
189 
190 	ab = sc->buf;
191 
192 	if (xchk_should_terminate(sc, &error))
193 		return error;
194 
195 	if (attr_flags & ~XFS_ATTR_ONDISK_MASK) {
196 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
197 		return -ECANCELED;
198 	}
199 
200 	if (attr_flags & XFS_ATTR_INCOMPLETE) {
201 		/* Incomplete attr key, just mark the inode for preening. */
202 		xchk_ino_set_preen(sc, ip->i_ino);
203 		return 0;
204 	}
205 
206 	/* Does this name make sense? */
207 	if (!xfs_attr_namecheck(attr_flags, name, namelen)) {
208 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
209 		return -ECANCELED;
210 	}
211 
212 	/* Check parent pointer record. */
213 	if ((attr_flags & XFS_ATTR_PARENT) &&
214 	    !xfs_parent_valuecheck(sc->mp, value, valuelen)) {
215 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
216 		return -ECANCELED;
217 	}
218 
219 	/*
220 	 * Try to allocate enough memory to extract the attr value.  If that
221 	 * doesn't work, return -EDEADLOCK as a signal to try again with a
222 	 * maximally sized buffer.
223 	 */
224 	error = xchk_setup_xattr_buf(sc, valuelen);
225 	if (error == -ENOMEM)
226 		error = -EDEADLOCK;
227 	if (error)
228 		return error;
229 
230 	/*
231 	 * Parent pointers are matched on attr name and value, so we must
232 	 * supply the xfs_parent_rec here when confirming that the dabtree
233 	 * indexing works correctly.
234 	 */
235 	if (attr_flags & XFS_ATTR_PARENT)
236 		memcpy(ab->value, value, valuelen);
237 
238 	args.value = ab->value;
239 
240 	/*
241 	 * Get the attr value to ensure that lookup can find this attribute
242 	 * through the dabtree indexing and that remote value retrieval also
243 	 * works correctly.
244 	 */
245 	xfs_attr_sethash(&args);
246 	error = xfs_attr_get_ilocked(&args);
247 	/* ENODATA means the hash lookup failed and the attr is bad */
248 	if (error == -ENODATA)
249 		error = -EFSCORRUPTED;
250 	if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, args.blkno,
251 			&error))
252 		return error;
253 	if (args.valuelen != valuelen)
254 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, args.blkno);
255 
256 	return 0;
257 }
258 
259 /*
260  * Mark a range [start, start+len) in this map.  Returns true if the
261  * region was free, and false if there's a conflict or a problem.
262  *
263  * Within a char, the lowest bit of the char represents the byte with
264  * the smallest address
265  */
266 bool
267 xchk_xattr_set_map(
268 	struct xfs_scrub	*sc,
269 	unsigned long		*map,
270 	unsigned int		start,
271 	unsigned int		len)
272 {
273 	unsigned int		mapsize = sc->mp->m_attr_geo->blksize;
274 	bool			ret = true;
275 
276 	if (start >= mapsize)
277 		return false;
278 	if (start + len > mapsize) {
279 		len = mapsize - start;
280 		ret = false;
281 	}
282 
283 	if (find_next_bit(map, mapsize, start) < start + len)
284 		ret = false;
285 	bitmap_set(map, start, len);
286 
287 	return ret;
288 }
289 
290 /*
291  * Check this leaf entry's relations to everything else.
292  * Returns the number of bytes used for the name/value data.
293  */
294 STATIC void
295 xchk_xattr_entry(
296 	struct xchk_da_btree		*ds,
297 	int				level,
298 	char				*buf_end,
299 	struct xfs_attr_leafblock	*leaf,
300 	struct xfs_attr3_icleaf_hdr	*leafhdr,
301 	struct xfs_attr_leaf_entry	*ent,
302 	int				idx,
303 	unsigned int			*usedbytes,
304 	__u32				*last_hashval)
305 {
306 	struct xfs_mount		*mp = ds->state->mp;
307 	struct xchk_xattr_buf		*ab = ds->sc->buf;
308 	char				*name_end;
309 	struct xfs_attr_leaf_name_local	*lentry;
310 	struct xfs_attr_leaf_name_remote *rentry;
311 	unsigned int			nameidx;
312 	unsigned int			namesize;
313 
314 	if (ent->pad2 != 0)
315 		xchk_da_set_corrupt(ds, level);
316 
317 	/* Hash values in order? */
318 	if (be32_to_cpu(ent->hashval) < *last_hashval)
319 		xchk_da_set_corrupt(ds, level);
320 	*last_hashval = be32_to_cpu(ent->hashval);
321 
322 	nameidx = be16_to_cpu(ent->nameidx);
323 	if (nameidx < leafhdr->firstused ||
324 	    nameidx >= mp->m_attr_geo->blksize) {
325 		xchk_da_set_corrupt(ds, level);
326 		return;
327 	}
328 
329 	/* Check the name information. */
330 	if (ent->flags & XFS_ATTR_LOCAL) {
331 		lentry = xfs_attr3_leaf_name_local(leaf, idx);
332 		namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
333 				be16_to_cpu(lentry->valuelen));
334 		name_end = (char *)lentry + namesize;
335 		if (lentry->namelen == 0)
336 			xchk_da_set_corrupt(ds, level);
337 	} else {
338 		rentry = xfs_attr3_leaf_name_remote(leaf, idx);
339 		namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
340 		name_end = (char *)rentry + namesize;
341 		if (rentry->namelen == 0)
342 			xchk_da_set_corrupt(ds, level);
343 		if (rentry->valueblk == 0 &&
344 		    !(ent->flags & XFS_ATTR_INCOMPLETE))
345 			xchk_da_set_corrupt(ds, level);
346 	}
347 	if (name_end > buf_end)
348 		xchk_da_set_corrupt(ds, level);
349 
350 	if (!xchk_xattr_set_map(ds->sc, ab->usedmap, nameidx, namesize))
351 		xchk_da_set_corrupt(ds, level);
352 	if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
353 		*usedbytes += namesize;
354 }
355 
356 /* Scrub an attribute leaf. */
357 STATIC int
358 xchk_xattr_block(
359 	struct xchk_da_btree		*ds,
360 	int				level)
361 {
362 	struct xfs_attr3_icleaf_hdr	leafhdr;
363 	struct xfs_mount		*mp = ds->state->mp;
364 	struct xfs_da_state_blk		*blk = &ds->state->path.blk[level];
365 	struct xfs_buf			*bp = blk->bp;
366 	xfs_dablk_t			*last_checked = ds->private;
367 	struct xfs_attr_leafblock	*leaf = bp->b_addr;
368 	struct xfs_attr_leaf_entry	*ent;
369 	struct xfs_attr_leaf_entry	*entries;
370 	struct xchk_xattr_buf		*ab = ds->sc->buf;
371 	char				*buf_end;
372 	size_t				off;
373 	__u32				last_hashval = 0;
374 	unsigned int			usedbytes = 0;
375 	unsigned int			hdrsize;
376 	int				i;
377 
378 	if (*last_checked == blk->blkno)
379 		return 0;
380 
381 	*last_checked = blk->blkno;
382 	bitmap_zero(ab->usedmap, mp->m_attr_geo->blksize);
383 	bitmap_zero(ab->freemap, mp->m_attr_geo->blksize);
384 
385 	/* Check all the padding. */
386 	if (xfs_has_crc(ds->sc->mp)) {
387 		struct xfs_attr3_leafblock	*leaf3 = bp->b_addr;
388 
389 		if (leaf3->hdr.pad1 != 0 || leaf3->hdr.pad2 != 0 ||
390 		    leaf3->hdr.info.hdr.pad != 0)
391 			xchk_da_set_corrupt(ds, level);
392 	} else {
393 		if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
394 			xchk_da_set_corrupt(ds, level);
395 	}
396 
397 	/* Check the leaf header */
398 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
399 	hdrsize = xfs_attr3_leaf_hdr_size(leaf);
400 
401 	/*
402 	 * Empty xattr leaf blocks mapped at block 0 are probably a byproduct
403 	 * of a race between setxattr and a log shutdown.  Anywhere else in the
404 	 * attr fork is a corruption.
405 	 */
406 	if (leafhdr.count == 0) {
407 		if (blk->blkno == 0)
408 			xchk_da_set_preen(ds, level);
409 		else
410 			xchk_da_set_corrupt(ds, level);
411 	}
412 	if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
413 		xchk_da_set_corrupt(ds, level);
414 	if (leafhdr.firstused > mp->m_attr_geo->blksize)
415 		xchk_da_set_corrupt(ds, level);
416 	if (leafhdr.firstused < hdrsize)
417 		xchk_da_set_corrupt(ds, level);
418 	if (!xchk_xattr_set_map(ds->sc, ab->usedmap, 0, hdrsize))
419 		xchk_da_set_corrupt(ds, level);
420 	if (leafhdr.holes)
421 		xchk_da_set_preen(ds, level);
422 
423 	if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
424 		goto out;
425 
426 	entries = xfs_attr3_leaf_entryp(leaf);
427 	if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
428 		xchk_da_set_corrupt(ds, level);
429 
430 	if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
431 		goto out;
432 
433 	buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
434 	for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
435 		/* Mark the leaf entry itself. */
436 		off = (char *)ent - (char *)leaf;
437 		if (!xchk_xattr_set_map(ds->sc, ab->usedmap, off,
438 				sizeof(xfs_attr_leaf_entry_t))) {
439 			xchk_da_set_corrupt(ds, level);
440 			goto out;
441 		}
442 
443 		/* Check the entry and nameval. */
444 		xchk_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
445 				ent, i, &usedbytes, &last_hashval);
446 
447 		if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
448 			goto out;
449 	}
450 
451 	/* Construct bitmap of freemap contents. */
452 	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
453 		if (!xchk_xattr_set_map(ds->sc, ab->freemap,
454 				leafhdr.freemap[i].base,
455 				leafhdr.freemap[i].size))
456 			xchk_da_set_corrupt(ds, level);
457 
458 		/*
459 		 * freemap entries with zero length and nonzero base can cause
460 		 * problems with older kernels, so we mark these for preening
461 		 * even though there's no inconsistency.
462 		 */
463 		if (leafhdr.freemap[i].size == 0 &&
464 		    leafhdr.freemap[i].base > 0)
465 			xchk_da_set_preen(ds, level);
466 
467 		if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
468 			goto out;
469 	}
470 
471 	/* Look for bits that are set in freemap and are marked in use. */
472 	if (bitmap_intersects(ab->freemap, ab->usedmap,
473 			mp->m_attr_geo->blksize))
474 		xchk_da_set_corrupt(ds, level);
475 
476 	if (leafhdr.usedbytes != usedbytes)
477 		xchk_da_set_corrupt(ds, level);
478 
479 out:
480 	return 0;
481 }
482 
483 /* Scrub a attribute btree record. */
484 STATIC int
485 xchk_xattr_rec(
486 	struct xchk_da_btree		*ds,
487 	int				level)
488 {
489 	struct xfs_mount		*mp = ds->state->mp;
490 	struct xfs_da_state_blk		*blk = &ds->state->path.blk[level];
491 	struct xfs_attr_leaf_name_local	*lentry;
492 	struct xfs_attr_leaf_name_remote	*rentry;
493 	struct xfs_buf			*bp;
494 	struct xfs_attr_leaf_entry	*ent;
495 	xfs_dahash_t			calc_hash;
496 	xfs_dahash_t			hash;
497 	int				nameidx;
498 	int				hdrsize;
499 	int				error;
500 
501 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
502 
503 	ent = xfs_attr3_leaf_entryp(blk->bp->b_addr) + blk->index;
504 
505 	/* Check the whole block, if necessary. */
506 	error = xchk_xattr_block(ds, level);
507 	if (error)
508 		goto out;
509 	if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
510 		goto out;
511 
512 	/* Check the hash of the entry. */
513 	error = xchk_da_btree_hash(ds, level, &ent->hashval);
514 	if (error)
515 		goto out;
516 
517 	/* Find the attr entry's location. */
518 	bp = blk->bp;
519 	hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
520 	nameidx = be16_to_cpu(ent->nameidx);
521 	if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
522 		xchk_da_set_corrupt(ds, level);
523 		goto out;
524 	}
525 
526 	/* Retrieve the entry and check it. */
527 	hash = be32_to_cpu(ent->hashval);
528 	if (ent->flags & ~XFS_ATTR_ONDISK_MASK) {
529 		xchk_da_set_corrupt(ds, level);
530 		return 0;
531 	}
532 	if (!xfs_attr_check_namespace(ent->flags)) {
533 		xchk_da_set_corrupt(ds, level);
534 		return 0;
535 	}
536 
537 	if (ent->flags & XFS_ATTR_LOCAL) {
538 		lentry = (struct xfs_attr_leaf_name_local *)
539 				(((char *)bp->b_addr) + nameidx);
540 		if (lentry->namelen <= 0) {
541 			xchk_da_set_corrupt(ds, level);
542 			goto out;
543 		}
544 		calc_hash = xfs_attr_hashval(mp, ent->flags, lentry->nameval,
545 					     lentry->namelen,
546 					     lentry->nameval + lentry->namelen,
547 					     be16_to_cpu(lentry->valuelen));
548 	} else {
549 		rentry = (struct xfs_attr_leaf_name_remote *)
550 				(((char *)bp->b_addr) + nameidx);
551 		if (rentry->namelen <= 0) {
552 			xchk_da_set_corrupt(ds, level);
553 			goto out;
554 		}
555 		if (ent->flags & XFS_ATTR_PARENT) {
556 			xchk_da_set_corrupt(ds, level);
557 			goto out;
558 		}
559 		calc_hash = xfs_attr_hashval(mp, ent->flags, rentry->name,
560 					     rentry->namelen, NULL,
561 					     be32_to_cpu(rentry->valuelen));
562 	}
563 	if (calc_hash != hash)
564 		xchk_da_set_corrupt(ds, level);
565 
566 out:
567 	return error;
568 }
569 
570 /* Check space usage of shortform attrs. */
571 STATIC int
572 xchk_xattr_check_sf(
573 	struct xfs_scrub		*sc)
574 {
575 	struct xchk_xattr_buf		*ab = sc->buf;
576 	struct xfs_ifork		*ifp = &sc->ip->i_af;
577 	struct xfs_attr_sf_hdr		*sf = ifp->if_data;
578 	struct xfs_attr_sf_entry	*sfe = xfs_attr_sf_firstentry(sf);
579 	struct xfs_attr_sf_entry	*next;
580 	unsigned char			*end = ifp->if_data + ifp->if_bytes;
581 	int				i;
582 	int				error = 0;
583 
584 	bitmap_zero(ab->usedmap, ifp->if_bytes);
585 	xchk_xattr_set_map(sc, ab->usedmap, 0, sizeof(*sf));
586 
587 	if ((unsigned char *)sfe > end) {
588 		xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
589 		return 0;
590 	}
591 
592 	for (i = 0; i < sf->count; i++) {
593 		unsigned char		*name = sfe->nameval;
594 		unsigned char		*value = &sfe->nameval[sfe->namelen];
595 
596 		if (xchk_should_terminate(sc, &error))
597 			return error;
598 
599 		next = xfs_attr_sf_nextentry(sfe);
600 		if ((unsigned char *)next > end) {
601 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
602 			break;
603 		}
604 
605 		/*
606 		 * Shortform entries do not set LOCAL or INCOMPLETE, so the
607 		 * only valid flag bits here are for namespaces.
608 		 */
609 		if (sfe->flags & ~XFS_ATTR_NSP_ONDISK_MASK) {
610 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
611 			break;
612 		}
613 
614 		if (!xchk_xattr_set_map(sc, ab->usedmap,
615 				(char *)sfe - (char *)sf,
616 				sizeof(struct xfs_attr_sf_entry))) {
617 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
618 			break;
619 		}
620 
621 		if (!xchk_xattr_set_map(sc, ab->usedmap,
622 				(char *)name - (char *)sf,
623 				sfe->namelen)) {
624 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
625 			break;
626 		}
627 
628 		if (!xchk_xattr_set_map(sc, ab->usedmap,
629 				(char *)value - (char *)sf,
630 				sfe->valuelen)) {
631 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
632 			break;
633 		}
634 
635 		sfe = next;
636 	}
637 
638 	return 0;
639 }
640 
641 /* Scrub the extended attribute metadata. */
642 int
643 xchk_xattr(
644 	struct xfs_scrub		*sc)
645 {
646 	xfs_dablk_t			last_checked = -1U;
647 	int				error = 0;
648 
649 	if (!xfs_inode_hasattr(sc->ip))
650 		return -ENOENT;
651 
652 	/* Allocate memory for xattr checking. */
653 	error = xchk_setup_xattr_buf(sc, 0);
654 	if (error == -ENOMEM)
655 		return -EDEADLOCK;
656 	if (error)
657 		return error;
658 
659 	/* Check the physical structure of the xattr. */
660 	if (sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL)
661 		error = xchk_xattr_check_sf(sc);
662 	else
663 		error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
664 				&last_checked);
665 	if (error)
666 		return error;
667 
668 	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
669 		return 0;
670 
671 	/*
672 	 * Look up every xattr in this file by name and hash.
673 	 *
674 	 * The VFS only locks i_rwsem when modifying attrs, so keep all
675 	 * three locks held because that's the only way to ensure we're
676 	 * the only thread poking into the da btree.  We traverse the da
677 	 * btree while holding a leaf buffer locked for the xattr name
678 	 * iteration, which doesn't really follow the usual buffer
679 	 * locking order.
680 	 */
681 	error = xchk_xattr_walk(sc, sc->ip, xchk_xattr_actor, NULL, NULL);
682 	if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
683 		return error;
684 
685 	return 0;
686 }
687