xref: /linux/fs/xfs/scrub/scrub.c (revision da51bbcdbace8f43adf6066934c3926b656376e5)
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_trans.h"
14 #include "xfs_inode.h"
15 #include "xfs_quota.h"
16 #include "xfs_qm.h"
17 #include "xfs_scrub.h"
18 #include "xfs_buf_mem.h"
19 #include "xfs_rmap.h"
20 #include "scrub/scrub.h"
21 #include "scrub/common.h"
22 #include "scrub/trace.h"
23 #include "scrub/repair.h"
24 #include "scrub/health.h"
25 #include "scrub/stats.h"
26 #include "scrub/xfile.h"
27 
28 /*
29  * Online Scrub and Repair
30  *
31  * Traditionally, XFS (the kernel driver) did not know how to check or
32  * repair on-disk data structures.  That task was left to the xfs_check
33  * and xfs_repair tools, both of which require taking the filesystem
34  * offline for a thorough but time consuming examination.  Online
35  * scrub & repair, on the other hand, enables us to check the metadata
36  * for obvious errors while carefully stepping around the filesystem's
37  * ongoing operations, locking rules, etc.
38  *
39  * Given that most XFS metadata consist of records stored in a btree,
40  * most of the checking functions iterate the btree blocks themselves
41  * looking for irregularities.  When a record block is encountered, each
42  * record can be checked for obviously bad values.  Record values can
43  * also be cross-referenced against other btrees to look for potential
44  * misunderstandings between pieces of metadata.
45  *
46  * It is expected that the checkers responsible for per-AG metadata
47  * structures will lock the AG headers (AGI, AGF, AGFL), iterate the
48  * metadata structure, and perform any relevant cross-referencing before
49  * unlocking the AG and returning the results to userspace.  These
50  * scrubbers must not keep an AG locked for too long to avoid tying up
51  * the block and inode allocators.
52  *
53  * Block maps and b-trees rooted in an inode present a special challenge
54  * because they can involve extents from any AG.  The general scrubber
55  * structure of lock -> check -> xref -> unlock still holds, but AG
56  * locking order rules /must/ be obeyed to avoid deadlocks.  The
57  * ordering rule, of course, is that we must lock in increasing AG
58  * order.  Helper functions are provided to track which AG headers we've
59  * already locked.  If we detect an imminent locking order violation, we
60  * can signal a potential deadlock, in which case the scrubber can jump
61  * out to the top level, lock all the AGs in order, and retry the scrub.
62  *
63  * For file data (directories, extended attributes, symlinks) scrub, we
64  * can simply lock the inode and walk the data.  For btree data
65  * (directories and attributes) we follow the same btree-scrubbing
66  * strategy outlined previously to check the records.
67  *
68  * We use a bit of trickery with transactions to avoid buffer deadlocks
69  * if there is a cycle in the metadata.  The basic problem is that
70  * travelling down a btree involves locking the current buffer at each
71  * tree level.  If a pointer should somehow point back to a buffer that
72  * we've already examined, we will deadlock due to the second buffer
73  * locking attempt.  Note however that grabbing a buffer in transaction
74  * context links the locked buffer to the transaction.  If we try to
75  * re-grab the buffer in the context of the same transaction, we avoid
76  * the second lock attempt and continue.  Between the verifier and the
77  * scrubber, something will notice that something is amiss and report
78  * the corruption.  Therefore, each scrubber will allocate an empty
79  * transaction, attach buffers to it, and cancel the transaction at the
80  * end of the scrub run.  Cancelling a non-dirty transaction simply
81  * unlocks the buffers.
82  *
83  * There are four pieces of data that scrub can communicate to
84  * userspace.  The first is the error code (errno), which can be used to
85  * communicate operational errors in performing the scrub.  There are
86  * also three flags that can be set in the scrub context.  If the data
87  * structure itself is corrupt, the CORRUPT flag will be set.  If
88  * the metadata is correct but otherwise suboptimal, the PREEN flag
89  * will be set.
90  *
91  * We perform secondary validation of filesystem metadata by
92  * cross-referencing every record with all other available metadata.
93  * For example, for block mapping extents, we verify that there are no
94  * records in the free space and inode btrees corresponding to that
95  * space extent and that there is a corresponding entry in the reverse
96  * mapping btree.  Inconsistent metadata is noted by setting the
97  * XCORRUPT flag; btree query function errors are noted by setting the
98  * XFAIL flag and deleting the cursor to prevent further attempts to
99  * cross-reference with a defective btree.
100  *
101  * If a piece of metadata proves corrupt or suboptimal, the userspace
102  * program can ask the kernel to apply some tender loving care (TLC) to
103  * the metadata object by setting the REPAIR flag and re-calling the
104  * scrub ioctl.  "Corruption" is defined by metadata violating the
105  * on-disk specification; operations cannot continue if the violation is
106  * left untreated.  It is possible for XFS to continue if an object is
107  * "suboptimal", however performance may be degraded.  Repairs are
108  * usually performed by rebuilding the metadata entirely out of
109  * redundant metadata.  Optimizing, on the other hand, can sometimes be
110  * done without rebuilding entire structures.
111  *
112  * Generally speaking, the repair code has the following code structure:
113  * Lock -> scrub -> repair -> commit -> re-lock -> re-scrub -> unlock.
114  * The first check helps us figure out if we need to rebuild or simply
115  * optimize the structure so that the rebuild knows what to do.  The
116  * second check evaluates the completeness of the repair; that is what
117  * is reported to userspace.
118  *
119  * A quick note on symbol prefixes:
120  * - "xfs_" are general XFS symbols.
121  * - "xchk_" are symbols related to metadata checking.
122  * - "xrep_" are symbols related to metadata repair.
123  * - "xfs_scrub_" are symbols that tie online fsck to the rest of XFS.
124  */
125 
126 /*
127  * Scrub probe -- userspace uses this to probe if we're willing to scrub
128  * or repair a given mountpoint.  This will be used by xfs_scrub to
129  * probe the kernel's abilities to scrub (and repair) the metadata.  We
130  * do this by validating the ioctl inputs from userspace, preparing the
131  * filesystem for a scrub (or a repair) operation, and immediately
132  * returning to userspace.  Userspace can use the returned errno and
133  * structure state to decide (in broad terms) if scrub/repair are
134  * supported by the running kernel.
135  */
136 static int
137 xchk_probe(
138 	struct xfs_scrub	*sc)
139 {
140 	int			error = 0;
141 
142 	if (xchk_should_terminate(sc, &error))
143 		return error;
144 
145 	return 0;
146 }
147 
148 /* Scrub setup and teardown */
149 
150 static inline void
151 xchk_fsgates_disable(
152 	struct xfs_scrub	*sc)
153 {
154 	if (!(sc->flags & XCHK_FSGATES_ALL))
155 		return;
156 
157 	trace_xchk_fsgates_disable(sc, sc->flags & XCHK_FSGATES_ALL);
158 
159 	if (sc->flags & XCHK_FSGATES_DRAIN)
160 		xfs_drain_wait_disable();
161 
162 	if (sc->flags & XCHK_FSGATES_QUOTA)
163 		xfs_dqtrx_hook_disable();
164 
165 	if (sc->flags & XCHK_FSGATES_DIRENTS)
166 		xfs_dir_hook_disable();
167 
168 	if (sc->flags & XCHK_FSGATES_RMAP)
169 		xfs_rmap_hook_disable();
170 
171 	sc->flags &= ~XCHK_FSGATES_ALL;
172 }
173 
174 /* Free all the resources and finish the transactions. */
175 STATIC int
176 xchk_teardown(
177 	struct xfs_scrub	*sc,
178 	int			error)
179 {
180 	xchk_ag_free(sc, &sc->sa);
181 	if (sc->tp) {
182 		if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
183 			error = xfs_trans_commit(sc->tp);
184 		else
185 			xfs_trans_cancel(sc->tp);
186 		sc->tp = NULL;
187 	}
188 	if (sc->ip) {
189 		if (sc->ilock_flags)
190 			xchk_iunlock(sc, sc->ilock_flags);
191 		xchk_irele(sc, sc->ip);
192 		sc->ip = NULL;
193 	}
194 	if (sc->flags & XCHK_HAVE_FREEZE_PROT) {
195 		sc->flags &= ~XCHK_HAVE_FREEZE_PROT;
196 		mnt_drop_write_file(sc->file);
197 	}
198 	if (sc->xmbtp) {
199 		xmbuf_free(sc->xmbtp);
200 		sc->xmbtp = NULL;
201 	}
202 	if (sc->xfile) {
203 		xfile_destroy(sc->xfile);
204 		sc->xfile = NULL;
205 	}
206 	if (sc->buf) {
207 		if (sc->buf_cleanup)
208 			sc->buf_cleanup(sc->buf);
209 		kvfree(sc->buf);
210 		sc->buf_cleanup = NULL;
211 		sc->buf = NULL;
212 	}
213 
214 	xchk_fsgates_disable(sc);
215 	return error;
216 }
217 
218 /* Scrubbing dispatch. */
219 
220 static const struct xchk_meta_ops meta_scrub_ops[] = {
221 	[XFS_SCRUB_TYPE_PROBE] = {	/* ioctl presence test */
222 		.type	= ST_NONE,
223 		.setup	= xchk_setup_fs,
224 		.scrub	= xchk_probe,
225 		.repair = xrep_probe,
226 	},
227 	[XFS_SCRUB_TYPE_SB] = {		/* superblock */
228 		.type	= ST_PERAG,
229 		.setup	= xchk_setup_agheader,
230 		.scrub	= xchk_superblock,
231 		.repair	= xrep_superblock,
232 	},
233 	[XFS_SCRUB_TYPE_AGF] = {	/* agf */
234 		.type	= ST_PERAG,
235 		.setup	= xchk_setup_agheader,
236 		.scrub	= xchk_agf,
237 		.repair	= xrep_agf,
238 	},
239 	[XFS_SCRUB_TYPE_AGFL]= {	/* agfl */
240 		.type	= ST_PERAG,
241 		.setup	= xchk_setup_agheader,
242 		.scrub	= xchk_agfl,
243 		.repair	= xrep_agfl,
244 	},
245 	[XFS_SCRUB_TYPE_AGI] = {	/* agi */
246 		.type	= ST_PERAG,
247 		.setup	= xchk_setup_agheader,
248 		.scrub	= xchk_agi,
249 		.repair	= xrep_agi,
250 	},
251 	[XFS_SCRUB_TYPE_BNOBT] = {	/* bnobt */
252 		.type	= ST_PERAG,
253 		.setup	= xchk_setup_ag_allocbt,
254 		.scrub	= xchk_allocbt,
255 		.repair	= xrep_allocbt,
256 		.repair_eval = xrep_revalidate_allocbt,
257 	},
258 	[XFS_SCRUB_TYPE_CNTBT] = {	/* cntbt */
259 		.type	= ST_PERAG,
260 		.setup	= xchk_setup_ag_allocbt,
261 		.scrub	= xchk_allocbt,
262 		.repair	= xrep_allocbt,
263 		.repair_eval = xrep_revalidate_allocbt,
264 	},
265 	[XFS_SCRUB_TYPE_INOBT] = {	/* inobt */
266 		.type	= ST_PERAG,
267 		.setup	= xchk_setup_ag_iallocbt,
268 		.scrub	= xchk_iallocbt,
269 		.repair	= xrep_iallocbt,
270 		.repair_eval = xrep_revalidate_iallocbt,
271 	},
272 	[XFS_SCRUB_TYPE_FINOBT] = {	/* finobt */
273 		.type	= ST_PERAG,
274 		.setup	= xchk_setup_ag_iallocbt,
275 		.scrub	= xchk_iallocbt,
276 		.has	= xfs_has_finobt,
277 		.repair	= xrep_iallocbt,
278 		.repair_eval = xrep_revalidate_iallocbt,
279 	},
280 	[XFS_SCRUB_TYPE_RMAPBT] = {	/* rmapbt */
281 		.type	= ST_PERAG,
282 		.setup	= xchk_setup_ag_rmapbt,
283 		.scrub	= xchk_rmapbt,
284 		.has	= xfs_has_rmapbt,
285 		.repair	= xrep_rmapbt,
286 	},
287 	[XFS_SCRUB_TYPE_REFCNTBT] = {	/* refcountbt */
288 		.type	= ST_PERAG,
289 		.setup	= xchk_setup_ag_refcountbt,
290 		.scrub	= xchk_refcountbt,
291 		.has	= xfs_has_reflink,
292 		.repair	= xrep_refcountbt,
293 	},
294 	[XFS_SCRUB_TYPE_INODE] = {	/* inode record */
295 		.type	= ST_INODE,
296 		.setup	= xchk_setup_inode,
297 		.scrub	= xchk_inode,
298 		.repair	= xrep_inode,
299 	},
300 	[XFS_SCRUB_TYPE_BMBTD] = {	/* inode data fork */
301 		.type	= ST_INODE,
302 		.setup	= xchk_setup_inode_bmap,
303 		.scrub	= xchk_bmap_data,
304 		.repair	= xrep_bmap_data,
305 	},
306 	[XFS_SCRUB_TYPE_BMBTA] = {	/* inode attr fork */
307 		.type	= ST_INODE,
308 		.setup	= xchk_setup_inode_bmap,
309 		.scrub	= xchk_bmap_attr,
310 		.repair	= xrep_bmap_attr,
311 	},
312 	[XFS_SCRUB_TYPE_BMBTC] = {	/* inode CoW fork */
313 		.type	= ST_INODE,
314 		.setup	= xchk_setup_inode_bmap,
315 		.scrub	= xchk_bmap_cow,
316 		.repair	= xrep_bmap_cow,
317 	},
318 	[XFS_SCRUB_TYPE_DIR] = {	/* directory */
319 		.type	= ST_INODE,
320 		.setup	= xchk_setup_directory,
321 		.scrub	= xchk_directory,
322 		.repair	= xrep_notsupported,
323 	},
324 	[XFS_SCRUB_TYPE_XATTR] = {	/* extended attributes */
325 		.type	= ST_INODE,
326 		.setup	= xchk_setup_xattr,
327 		.scrub	= xchk_xattr,
328 		.repair	= xrep_notsupported,
329 	},
330 	[XFS_SCRUB_TYPE_SYMLINK] = {	/* symbolic link */
331 		.type	= ST_INODE,
332 		.setup	= xchk_setup_symlink,
333 		.scrub	= xchk_symlink,
334 		.repair	= xrep_notsupported,
335 	},
336 	[XFS_SCRUB_TYPE_PARENT] = {	/* parent pointers */
337 		.type	= ST_INODE,
338 		.setup	= xchk_setup_parent,
339 		.scrub	= xchk_parent,
340 		.repair	= xrep_notsupported,
341 	},
342 	[XFS_SCRUB_TYPE_RTBITMAP] = {	/* realtime bitmap */
343 		.type	= ST_FS,
344 		.setup	= xchk_setup_rtbitmap,
345 		.scrub	= xchk_rtbitmap,
346 		.repair	= xrep_rtbitmap,
347 	},
348 	[XFS_SCRUB_TYPE_RTSUM] = {	/* realtime summary */
349 		.type	= ST_FS,
350 		.setup	= xchk_setup_rtsummary,
351 		.scrub	= xchk_rtsummary,
352 		.repair	= xrep_notsupported,
353 	},
354 	[XFS_SCRUB_TYPE_UQUOTA] = {	/* user quota */
355 		.type	= ST_FS,
356 		.setup	= xchk_setup_quota,
357 		.scrub	= xchk_quota,
358 		.repair	= xrep_quota,
359 	},
360 	[XFS_SCRUB_TYPE_GQUOTA] = {	/* group quota */
361 		.type	= ST_FS,
362 		.setup	= xchk_setup_quota,
363 		.scrub	= xchk_quota,
364 		.repair	= xrep_quota,
365 	},
366 	[XFS_SCRUB_TYPE_PQUOTA] = {	/* project quota */
367 		.type	= ST_FS,
368 		.setup	= xchk_setup_quota,
369 		.scrub	= xchk_quota,
370 		.repair	= xrep_quota,
371 	},
372 	[XFS_SCRUB_TYPE_FSCOUNTERS] = {	/* fs summary counters */
373 		.type	= ST_FS,
374 		.setup	= xchk_setup_fscounters,
375 		.scrub	= xchk_fscounters,
376 		.repair	= xrep_fscounters,
377 	},
378 	[XFS_SCRUB_TYPE_QUOTACHECK] = {	/* quota counters */
379 		.type	= ST_FS,
380 		.setup	= xchk_setup_quotacheck,
381 		.scrub	= xchk_quotacheck,
382 		.repair	= xrep_quotacheck,
383 	},
384 	[XFS_SCRUB_TYPE_NLINKS] = {	/* inode link counts */
385 		.type	= ST_FS,
386 		.setup	= xchk_setup_nlinks,
387 		.scrub	= xchk_nlinks,
388 		.repair	= xrep_nlinks,
389 	},
390 	[XFS_SCRUB_TYPE_HEALTHY] = {	/* fs healthy; clean all reminders */
391 		.type	= ST_FS,
392 		.setup	= xchk_setup_fs,
393 		.scrub	= xchk_health_record,
394 		.repair = xrep_notsupported,
395 	},
396 };
397 
398 static int
399 xchk_validate_inputs(
400 	struct xfs_mount		*mp,
401 	struct xfs_scrub_metadata	*sm)
402 {
403 	int				error;
404 	const struct xchk_meta_ops	*ops;
405 
406 	error = -EINVAL;
407 	/* Check our inputs. */
408 	sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT;
409 	if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN)
410 		goto out;
411 	/* sm_reserved[] must be zero */
412 	if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved)))
413 		goto out;
414 
415 	error = -ENOENT;
416 	/* Do we know about this type of metadata? */
417 	if (sm->sm_type >= XFS_SCRUB_TYPE_NR)
418 		goto out;
419 	ops = &meta_scrub_ops[sm->sm_type];
420 	if (ops->setup == NULL || ops->scrub == NULL)
421 		goto out;
422 	/* Does this fs even support this type of metadata? */
423 	if (ops->has && !ops->has(mp))
424 		goto out;
425 
426 	error = -EINVAL;
427 	/* restricting fields must be appropriate for type */
428 	switch (ops->type) {
429 	case ST_NONE:
430 	case ST_FS:
431 		if (sm->sm_ino || sm->sm_gen || sm->sm_agno)
432 			goto out;
433 		break;
434 	case ST_PERAG:
435 		if (sm->sm_ino || sm->sm_gen ||
436 		    sm->sm_agno >= mp->m_sb.sb_agcount)
437 			goto out;
438 		break;
439 	case ST_INODE:
440 		if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino))
441 			goto out;
442 		break;
443 	default:
444 		goto out;
445 	}
446 
447 	/* No rebuild without repair. */
448 	if ((sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) &&
449 	    !(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
450 		return -EINVAL;
451 
452 	/*
453 	 * We only want to repair read-write v5+ filesystems.  Defer the check
454 	 * for ops->repair until after our scrub confirms that we need to
455 	 * perform repairs so that we avoid failing due to not supporting
456 	 * repairing an object that doesn't need repairs.
457 	 */
458 	if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) {
459 		error = -EOPNOTSUPP;
460 		if (!xfs_has_crc(mp))
461 			goto out;
462 
463 		error = -EROFS;
464 		if (xfs_is_readonly(mp))
465 			goto out;
466 	}
467 
468 	error = 0;
469 out:
470 	return error;
471 }
472 
473 #ifdef CONFIG_XFS_ONLINE_REPAIR
474 static inline void xchk_postmortem(struct xfs_scrub *sc)
475 {
476 	/*
477 	 * Userspace asked us to repair something, we repaired it, rescanned
478 	 * it, and the rescan says it's still broken.  Scream about this in
479 	 * the system logs.
480 	 */
481 	if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) &&
482 	    (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
483 				 XFS_SCRUB_OFLAG_XCORRUPT)))
484 		xrep_failure(sc->mp);
485 }
486 #else
487 static inline void xchk_postmortem(struct xfs_scrub *sc)
488 {
489 	/*
490 	 * Userspace asked us to scrub something, it's broken, and we have no
491 	 * way of fixing it.  Scream in the logs.
492 	 */
493 	if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
494 				XFS_SCRUB_OFLAG_XCORRUPT))
495 		xfs_alert_ratelimited(sc->mp,
496 				"Corruption detected during scrub.");
497 }
498 #endif /* CONFIG_XFS_ONLINE_REPAIR */
499 
500 /* Dispatch metadata scrubbing. */
501 int
502 xfs_scrub_metadata(
503 	struct file			*file,
504 	struct xfs_scrub_metadata	*sm)
505 {
506 	struct xchk_stats_run		run = { };
507 	struct xfs_scrub		*sc;
508 	struct xfs_mount		*mp = XFS_I(file_inode(file))->i_mount;
509 	u64				check_start;
510 	int				error = 0;
511 
512 	BUILD_BUG_ON(sizeof(meta_scrub_ops) !=
513 		(sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR));
514 
515 	trace_xchk_start(XFS_I(file_inode(file)), sm, error);
516 
517 	/* Forbidden if we are shut down or mounted norecovery. */
518 	error = -ESHUTDOWN;
519 	if (xfs_is_shutdown(mp))
520 		goto out;
521 	error = -ENOTRECOVERABLE;
522 	if (xfs_has_norecovery(mp))
523 		goto out;
524 
525 	error = xchk_validate_inputs(mp, sm);
526 	if (error)
527 		goto out;
528 
529 	xfs_warn_mount(mp, XFS_OPSTATE_WARNED_SCRUB,
530  "EXPERIMENTAL online scrub feature in use. Use at your own risk!");
531 
532 	sc = kzalloc(sizeof(struct xfs_scrub), XCHK_GFP_FLAGS);
533 	if (!sc) {
534 		error = -ENOMEM;
535 		goto out;
536 	}
537 
538 	sc->mp = mp;
539 	sc->file = file;
540 	sc->sm = sm;
541 	sc->ops = &meta_scrub_ops[sm->sm_type];
542 	sc->sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type);
543 retry_op:
544 	/*
545 	 * When repairs are allowed, prevent freezing or readonly remount while
546 	 * scrub is running with a real transaction.
547 	 */
548 	if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) {
549 		error = mnt_want_write_file(sc->file);
550 		if (error)
551 			goto out_sc;
552 
553 		sc->flags |= XCHK_HAVE_FREEZE_PROT;
554 	}
555 
556 	/* Set up for the operation. */
557 	error = sc->ops->setup(sc);
558 	if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER))
559 		goto try_harder;
560 	if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN))
561 		goto need_drain;
562 	if (error)
563 		goto out_teardown;
564 
565 	/* Scrub for errors. */
566 	check_start = xchk_stats_now();
567 	if ((sc->flags & XREP_ALREADY_FIXED) && sc->ops->repair_eval != NULL)
568 		error = sc->ops->repair_eval(sc);
569 	else
570 		error = sc->ops->scrub(sc);
571 	run.scrub_ns += xchk_stats_elapsed_ns(check_start);
572 	if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER))
573 		goto try_harder;
574 	if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN))
575 		goto need_drain;
576 	if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE))
577 		goto out_teardown;
578 
579 	xchk_update_health(sc);
580 
581 	if (xchk_could_repair(sc)) {
582 		/*
583 		 * If userspace asked for a repair but it wasn't necessary,
584 		 * report that back to userspace.
585 		 */
586 		if (!xrep_will_attempt(sc)) {
587 			sc->sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED;
588 			goto out_nofix;
589 		}
590 
591 		/*
592 		 * If it's broken, userspace wants us to fix it, and we haven't
593 		 * already tried to fix it, then attempt a repair.
594 		 */
595 		error = xrep_attempt(sc, &run);
596 		if (error == -EAGAIN) {
597 			/*
598 			 * Either the repair function succeeded or it couldn't
599 			 * get all the resources it needs; either way, we go
600 			 * back to the beginning and call the scrub function.
601 			 */
602 			error = xchk_teardown(sc, 0);
603 			if (error) {
604 				xrep_failure(mp);
605 				goto out_sc;
606 			}
607 			goto retry_op;
608 		}
609 	}
610 
611 out_nofix:
612 	xchk_postmortem(sc);
613 out_teardown:
614 	error = xchk_teardown(sc, error);
615 out_sc:
616 	if (error != -ENOENT)
617 		xchk_stats_merge(mp, sm, &run);
618 	kfree(sc);
619 out:
620 	trace_xchk_done(XFS_I(file_inode(file)), sm, error);
621 	if (error == -EFSCORRUPTED || error == -EFSBADCRC) {
622 		sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
623 		error = 0;
624 	}
625 	return error;
626 need_drain:
627 	error = xchk_teardown(sc, 0);
628 	if (error)
629 		goto out_sc;
630 	sc->flags |= XCHK_NEED_DRAIN;
631 	run.retries++;
632 	goto retry_op;
633 try_harder:
634 	/*
635 	 * Scrubbers return -EDEADLOCK to mean 'try harder'.  Tear down
636 	 * everything we hold, then set up again with preparation for
637 	 * worst-case scenarios.
638 	 */
639 	error = xchk_teardown(sc, 0);
640 	if (error)
641 		goto out_sc;
642 	sc->flags |= XCHK_TRY_HARDER;
643 	run.retries++;
644 	goto retry_op;
645 }
646