xref: /openbmc/linux/fs/xfs/scrub/attr.c (revision 20adb1e2)
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.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
xchk_xattr_buf_cleanup(void * priv)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
xchk_xattr_want_freemap(struct xfs_scrub * sc)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
xchk_setup_xattr_buf(struct xfs_scrub * sc,size_t value_size)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
xchk_setup_xattr(struct xfs_scrub * sc)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
xchk_xattr_listent(struct xfs_attr_list_context * context,int flags,unsigned char * name,int namelen,int valuelen)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_ONDISK_MASK) {
186 		xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
187 		goto fail_xref;
188 	}
189 
190 	if (flags & XFS_ATTR_INCOMPLETE) {
191 		/* Incomplete attr key, just mark the inode for preening. */
192 		xchk_ino_set_preen(sx->sc, context->dp->i_ino);
193 		return;
194 	}
195 
196 	/* Does this name make sense? */
197 	if (!xfs_attr_namecheck(flags, name, namelen)) {
198 		xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
199 		goto fail_xref;
200 	}
201 
202 	/*
203 	 * Try to allocate enough memory to extrat the attr value.  If that
204 	 * doesn't work, we overload the seen_enough variable to convey
205 	 * the error message back to the main scrub function.
206 	 */
207 	error = xchk_setup_xattr_buf(sx->sc, valuelen);
208 	if (error == -ENOMEM)
209 		error = -EDEADLOCK;
210 	if (error) {
211 		context->seen_enough = error;
212 		return;
213 	}
214 
215 	args.value = ab->value;
216 
217 	/*
218 	 * Get the attr value to ensure that lookup can find this attribute
219 	 * through the dabtree indexing and that remote value retrieval also
220 	 * works correctly.
221 	 */
222 	error = xfs_attr_get_ilocked(&args);
223 	/* ENODATA means the hash lookup failed and the attr is bad */
224 	if (error == -ENODATA)
225 		error = -EFSCORRUPTED;
226 	if (!xchk_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
227 			&error))
228 		goto fail_xref;
229 	if (args.valuelen != valuelen)
230 		xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
231 					     args.blkno);
232 fail_xref:
233 	if (sx->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
234 		context->seen_enough = 1;
235 	return;
236 }
237 
238 /*
239  * Mark a range [start, start+len) in this map.  Returns true if the
240  * region was free, and false if there's a conflict or a problem.
241  *
242  * Within a char, the lowest bit of the char represents the byte with
243  * the smallest address
244  */
245 STATIC bool
xchk_xattr_set_map(struct xfs_scrub * sc,unsigned long * map,unsigned int start,unsigned int len)246 xchk_xattr_set_map(
247 	struct xfs_scrub	*sc,
248 	unsigned long		*map,
249 	unsigned int		start,
250 	unsigned int		len)
251 {
252 	unsigned int		mapsize = sc->mp->m_attr_geo->blksize;
253 	bool			ret = true;
254 
255 	if (start >= mapsize)
256 		return false;
257 	if (start + len > mapsize) {
258 		len = mapsize - start;
259 		ret = false;
260 	}
261 
262 	if (find_next_bit(map, mapsize, start) < start + len)
263 		ret = false;
264 	bitmap_set(map, start, len);
265 
266 	return ret;
267 }
268 
269 /*
270  * Check the leaf freemap from the usage bitmap.  Returns false if the
271  * attr freemap has problems or points to used space.
272  */
273 STATIC bool
xchk_xattr_check_freemap(struct xfs_scrub * sc,struct xfs_attr3_icleaf_hdr * leafhdr)274 xchk_xattr_check_freemap(
275 	struct xfs_scrub		*sc,
276 	struct xfs_attr3_icleaf_hdr	*leafhdr)
277 {
278 	struct xchk_xattr_buf		*ab = sc->buf;
279 	unsigned int			mapsize = sc->mp->m_attr_geo->blksize;
280 	int				i;
281 
282 	/* Construct bitmap of freemap contents. */
283 	bitmap_zero(ab->freemap, mapsize);
284 	for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
285 		if (!xchk_xattr_set_map(sc, ab->freemap,
286 				leafhdr->freemap[i].base,
287 				leafhdr->freemap[i].size))
288 			return false;
289 	}
290 
291 	/* Look for bits that are set in freemap and are marked in use. */
292 	return !bitmap_intersects(ab->freemap, ab->usedmap, mapsize);
293 }
294 
295 /*
296  * Check this leaf entry's relations to everything else.
297  * Returns the number of bytes used for the name/value data.
298  */
299 STATIC void
xchk_xattr_entry(struct xchk_da_btree * ds,int level,char * buf_end,struct xfs_attr_leafblock * leaf,struct xfs_attr3_icleaf_hdr * leafhdr,struct xfs_attr_leaf_entry * ent,int idx,unsigned int * usedbytes,__u32 * last_hashval)300 xchk_xattr_entry(
301 	struct xchk_da_btree		*ds,
302 	int				level,
303 	char				*buf_end,
304 	struct xfs_attr_leafblock	*leaf,
305 	struct xfs_attr3_icleaf_hdr	*leafhdr,
306 	struct xfs_attr_leaf_entry	*ent,
307 	int				idx,
308 	unsigned int			*usedbytes,
309 	__u32				*last_hashval)
310 {
311 	struct xfs_mount		*mp = ds->state->mp;
312 	struct xchk_xattr_buf		*ab = ds->sc->buf;
313 	char				*name_end;
314 	struct xfs_attr_leaf_name_local	*lentry;
315 	struct xfs_attr_leaf_name_remote *rentry;
316 	unsigned int			nameidx;
317 	unsigned int			namesize;
318 
319 	if (ent->pad2 != 0)
320 		xchk_da_set_corrupt(ds, level);
321 
322 	/* Hash values in order? */
323 	if (be32_to_cpu(ent->hashval) < *last_hashval)
324 		xchk_da_set_corrupt(ds, level);
325 	*last_hashval = be32_to_cpu(ent->hashval);
326 
327 	nameidx = be16_to_cpu(ent->nameidx);
328 	if (nameidx < leafhdr->firstused ||
329 	    nameidx >= mp->m_attr_geo->blksize) {
330 		xchk_da_set_corrupt(ds, level);
331 		return;
332 	}
333 
334 	/* Check the name information. */
335 	if (ent->flags & XFS_ATTR_LOCAL) {
336 		lentry = xfs_attr3_leaf_name_local(leaf, idx);
337 		namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
338 				be16_to_cpu(lentry->valuelen));
339 		name_end = (char *)lentry + namesize;
340 		if (lentry->namelen == 0)
341 			xchk_da_set_corrupt(ds, level);
342 	} else {
343 		rentry = xfs_attr3_leaf_name_remote(leaf, idx);
344 		namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
345 		name_end = (char *)rentry + namesize;
346 		if (rentry->namelen == 0 || rentry->valueblk == 0)
347 			xchk_da_set_corrupt(ds, level);
348 	}
349 	if (name_end > buf_end)
350 		xchk_da_set_corrupt(ds, level);
351 
352 	if (!xchk_xattr_set_map(ds->sc, ab->usedmap, nameidx, namesize))
353 		xchk_da_set_corrupt(ds, level);
354 	if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
355 		*usedbytes += namesize;
356 }
357 
358 /* Scrub an attribute leaf. */
359 STATIC int
xchk_xattr_block(struct xchk_da_btree * ds,int level)360 xchk_xattr_block(
361 	struct xchk_da_btree		*ds,
362 	int				level)
363 {
364 	struct xfs_attr3_icleaf_hdr	leafhdr;
365 	struct xfs_mount		*mp = ds->state->mp;
366 	struct xfs_da_state_blk		*blk = &ds->state->path.blk[level];
367 	struct xfs_buf			*bp = blk->bp;
368 	xfs_dablk_t			*last_checked = ds->private;
369 	struct xfs_attr_leafblock	*leaf = bp->b_addr;
370 	struct xfs_attr_leaf_entry	*ent;
371 	struct xfs_attr_leaf_entry	*entries;
372 	struct xchk_xattr_buf		*ab = ds->sc->buf;
373 	char				*buf_end;
374 	size_t				off;
375 	__u32				last_hashval = 0;
376 	unsigned int			usedbytes = 0;
377 	unsigned int			hdrsize;
378 	int				i;
379 
380 	if (*last_checked == blk->blkno)
381 		return 0;
382 
383 	*last_checked = blk->blkno;
384 	bitmap_zero(ab->usedmap, mp->m_attr_geo->blksize);
385 
386 	/* Check all the padding. */
387 	if (xfs_has_crc(ds->sc->mp)) {
388 		struct xfs_attr3_leafblock	*leaf3 = bp->b_addr;
389 
390 		if (leaf3->hdr.pad1 != 0 || leaf3->hdr.pad2 != 0 ||
391 		    leaf3->hdr.info.hdr.pad != 0)
392 			xchk_da_set_corrupt(ds, level);
393 	} else {
394 		if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
395 			xchk_da_set_corrupt(ds, level);
396 	}
397 
398 	/* Check the leaf header */
399 	xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
400 	hdrsize = xfs_attr3_leaf_hdr_size(leaf);
401 
402 	if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
403 		xchk_da_set_corrupt(ds, level);
404 	if (leafhdr.firstused > mp->m_attr_geo->blksize)
405 		xchk_da_set_corrupt(ds, level);
406 	if (leafhdr.firstused < hdrsize)
407 		xchk_da_set_corrupt(ds, level);
408 	if (!xchk_xattr_set_map(ds->sc, ab->usedmap, 0, hdrsize))
409 		xchk_da_set_corrupt(ds, level);
410 
411 	if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
412 		goto out;
413 
414 	entries = xfs_attr3_leaf_entryp(leaf);
415 	if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
416 		xchk_da_set_corrupt(ds, level);
417 
418 	buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
419 	for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
420 		/* Mark the leaf entry itself. */
421 		off = (char *)ent - (char *)leaf;
422 		if (!xchk_xattr_set_map(ds->sc, ab->usedmap, off,
423 				sizeof(xfs_attr_leaf_entry_t))) {
424 			xchk_da_set_corrupt(ds, level);
425 			goto out;
426 		}
427 
428 		/* Check the entry and nameval. */
429 		xchk_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
430 				ent, i, &usedbytes, &last_hashval);
431 
432 		if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
433 			goto out;
434 	}
435 
436 	if (!xchk_xattr_check_freemap(ds->sc, &leafhdr))
437 		xchk_da_set_corrupt(ds, level);
438 
439 	if (leafhdr.usedbytes != usedbytes)
440 		xchk_da_set_corrupt(ds, level);
441 
442 out:
443 	return 0;
444 }
445 
446 /* Scrub a attribute btree record. */
447 STATIC int
xchk_xattr_rec(struct xchk_da_btree * ds,int level)448 xchk_xattr_rec(
449 	struct xchk_da_btree		*ds,
450 	int				level)
451 {
452 	struct xfs_mount		*mp = ds->state->mp;
453 	struct xfs_da_state_blk		*blk = &ds->state->path.blk[level];
454 	struct xfs_attr_leaf_name_local	*lentry;
455 	struct xfs_attr_leaf_name_remote	*rentry;
456 	struct xfs_buf			*bp;
457 	struct xfs_attr_leaf_entry	*ent;
458 	xfs_dahash_t			calc_hash;
459 	xfs_dahash_t			hash;
460 	int				nameidx;
461 	int				hdrsize;
462 	int				error;
463 
464 	ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
465 
466 	ent = xfs_attr3_leaf_entryp(blk->bp->b_addr) + blk->index;
467 
468 	/* Check the whole block, if necessary. */
469 	error = xchk_xattr_block(ds, level);
470 	if (error)
471 		goto out;
472 	if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
473 		goto out;
474 
475 	/* Check the hash of the entry. */
476 	error = xchk_da_btree_hash(ds, level, &ent->hashval);
477 	if (error)
478 		goto out;
479 
480 	/* Find the attr entry's location. */
481 	bp = blk->bp;
482 	hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
483 	nameidx = be16_to_cpu(ent->nameidx);
484 	if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
485 		xchk_da_set_corrupt(ds, level);
486 		goto out;
487 	}
488 
489 	/* Retrieve the entry and check it. */
490 	hash = be32_to_cpu(ent->hashval);
491 	if (ent->flags & ~XFS_ATTR_ONDISK_MASK) {
492 		xchk_da_set_corrupt(ds, level);
493 		return 0;
494 	}
495 	if (!xfs_attr_check_namespace(ent->flags)) {
496 		xchk_da_set_corrupt(ds, level);
497 		return 0;
498 	}
499 
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
xchk_xattr_check_sf(struct xfs_scrub * sc)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 		/*
565 		 * Shortform entries do not set LOCAL or INCOMPLETE, so the
566 		 * only valid flag bits here are for namespaces.
567 		 */
568 		if (sfe->flags & ~XFS_ATTR_NSP_ONDISK_MASK) {
569 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
570 			break;
571 		}
572 
573 		if (!xchk_xattr_set_map(sc, ab->usedmap,
574 				(char *)sfe - (char *)sf,
575 				sizeof(struct xfs_attr_sf_entry))) {
576 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
577 			break;
578 		}
579 
580 		if (!xchk_xattr_set_map(sc, ab->usedmap,
581 				(char *)name - (char *)sf,
582 				sfe->namelen)) {
583 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
584 			break;
585 		}
586 
587 		if (!xchk_xattr_set_map(sc, ab->usedmap,
588 				(char *)value - (char *)sf,
589 				sfe->valuelen)) {
590 			xchk_fblock_set_corrupt(sc, XFS_ATTR_FORK, 0);
591 			break;
592 		}
593 
594 		sfe = next;
595 	}
596 
597 	return 0;
598 }
599 
600 /* Scrub the extended attribute metadata. */
601 int
xchk_xattr(struct xfs_scrub * sc)602 xchk_xattr(
603 	struct xfs_scrub		*sc)
604 {
605 	struct xchk_xattr		sx = {
606 		.sc			= sc,
607 		.context		= {
608 			.dp		= sc->ip,
609 			.tp		= sc->tp,
610 			.resynch	= 1,
611 			.put_listent	= xchk_xattr_listent,
612 			.allow_incomplete = true,
613 		},
614 	};
615 	xfs_dablk_t			last_checked = -1U;
616 	int				error = 0;
617 
618 	if (!xfs_inode_hasattr(sc->ip))
619 		return -ENOENT;
620 
621 	/* Allocate memory for xattr checking. */
622 	error = xchk_setup_xattr_buf(sc, 0);
623 	if (error == -ENOMEM)
624 		return -EDEADLOCK;
625 	if (error)
626 		return error;
627 
628 	/* Check the physical structure of the xattr. */
629 	if (sc->ip->i_af.if_format == XFS_DINODE_FMT_LOCAL)
630 		error = xchk_xattr_check_sf(sc);
631 	else
632 		error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
633 				&last_checked);
634 	if (error)
635 		return error;
636 
637 	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
638 		return 0;
639 
640 	/*
641 	 * Look up every xattr in this file by name and hash.
642 	 *
643 	 * Use the backend implementation of xfs_attr_list to call
644 	 * xchk_xattr_listent on every attribute key in this inode.
645 	 * In other words, we use the same iterator/callback mechanism
646 	 * that listattr uses to scrub extended attributes, though in our
647 	 * _listent function, we check the value of the attribute.
648 	 *
649 	 * The VFS only locks i_rwsem when modifying attrs, so keep all
650 	 * three locks held because that's the only way to ensure we're
651 	 * the only thread poking into the da btree.  We traverse the da
652 	 * btree while holding a leaf buffer locked for the xattr name
653 	 * iteration, which doesn't really follow the usual buffer
654 	 * locking order.
655 	 */
656 	error = xfs_attr_list_ilocked(&sx.context);
657 	if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
658 		return error;
659 
660 	/* Did our listent function try to return any errors? */
661 	if (sx.context.seen_enough < 0)
662 		return sx.context.seen_enough;
663 
664 	return 0;
665 }
666