Loading...
Note: File does not exist in v3.5.6.
1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Copyright (C) 2017 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
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_errortag.h"
18#include "xfs_error.h"
19#include "xfs_scrub.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
26/*
27 * Online Scrub and Repair
28 *
29 * Traditionally, XFS (the kernel driver) did not know how to check or
30 * repair on-disk data structures. That task was left to the xfs_check
31 * and xfs_repair tools, both of which require taking the filesystem
32 * offline for a thorough but time consuming examination. Online
33 * scrub & repair, on the other hand, enables us to check the metadata
34 * for obvious errors while carefully stepping around the filesystem's
35 * ongoing operations, locking rules, etc.
36 *
37 * Given that most XFS metadata consist of records stored in a btree,
38 * most of the checking functions iterate the btree blocks themselves
39 * looking for irregularities. When a record block is encountered, each
40 * record can be checked for obviously bad values. Record values can
41 * also be cross-referenced against other btrees to look for potential
42 * misunderstandings between pieces of metadata.
43 *
44 * It is expected that the checkers responsible for per-AG metadata
45 * structures will lock the AG headers (AGI, AGF, AGFL), iterate the
46 * metadata structure, and perform any relevant cross-referencing before
47 * unlocking the AG and returning the results to userspace. These
48 * scrubbers must not keep an AG locked for too long to avoid tying up
49 * the block and inode allocators.
50 *
51 * Block maps and b-trees rooted in an inode present a special challenge
52 * because they can involve extents from any AG. The general scrubber
53 * structure of lock -> check -> xref -> unlock still holds, but AG
54 * locking order rules /must/ be obeyed to avoid deadlocks. The
55 * ordering rule, of course, is that we must lock in increasing AG
56 * order. Helper functions are provided to track which AG headers we've
57 * already locked. If we detect an imminent locking order violation, we
58 * can signal a potential deadlock, in which case the scrubber can jump
59 * out to the top level, lock all the AGs in order, and retry the scrub.
60 *
61 * For file data (directories, extended attributes, symlinks) scrub, we
62 * can simply lock the inode and walk the data. For btree data
63 * (directories and attributes) we follow the same btree-scrubbing
64 * strategy outlined previously to check the records.
65 *
66 * We use a bit of trickery with transactions to avoid buffer deadlocks
67 * if there is a cycle in the metadata. The basic problem is that
68 * travelling down a btree involves locking the current buffer at each
69 * tree level. If a pointer should somehow point back to a buffer that
70 * we've already examined, we will deadlock due to the second buffer
71 * locking attempt. Note however that grabbing a buffer in transaction
72 * context links the locked buffer to the transaction. If we try to
73 * re-grab the buffer in the context of the same transaction, we avoid
74 * the second lock attempt and continue. Between the verifier and the
75 * scrubber, something will notice that something is amiss and report
76 * the corruption. Therefore, each scrubber will allocate an empty
77 * transaction, attach buffers to it, and cancel the transaction at the
78 * end of the scrub run. Cancelling a non-dirty transaction simply
79 * unlocks the buffers.
80 *
81 * There are four pieces of data that scrub can communicate to
82 * userspace. The first is the error code (errno), which can be used to
83 * communicate operational errors in performing the scrub. There are
84 * also three flags that can be set in the scrub context. If the data
85 * structure itself is corrupt, the CORRUPT flag will be set. If
86 * the metadata is correct but otherwise suboptimal, the PREEN flag
87 * will be set.
88 *
89 * We perform secondary validation of filesystem metadata by
90 * cross-referencing every record with all other available metadata.
91 * For example, for block mapping extents, we verify that there are no
92 * records in the free space and inode btrees corresponding to that
93 * space extent and that there is a corresponding entry in the reverse
94 * mapping btree. Inconsistent metadata is noted by setting the
95 * XCORRUPT flag; btree query function errors are noted by setting the
96 * XFAIL flag and deleting the cursor to prevent further attempts to
97 * cross-reference with a defective btree.
98 *
99 * If a piece of metadata proves corrupt or suboptimal, the userspace
100 * program can ask the kernel to apply some tender loving care (TLC) to
101 * the metadata object by setting the REPAIR flag and re-calling the
102 * scrub ioctl. "Corruption" is defined by metadata violating the
103 * on-disk specification; operations cannot continue if the violation is
104 * left untreated. It is possible for XFS to continue if an object is
105 * "suboptimal", however performance may be degraded. Repairs are
106 * usually performed by rebuilding the metadata entirely out of
107 * redundant metadata. Optimizing, on the other hand, can sometimes be
108 * done without rebuilding entire structures.
109 *
110 * Generally speaking, the repair code has the following code structure:
111 * Lock -> scrub -> repair -> commit -> re-lock -> re-scrub -> unlock.
112 * The first check helps us figure out if we need to rebuild or simply
113 * optimize the structure so that the rebuild knows what to do. The
114 * second check evaluates the completeness of the repair; that is what
115 * is reported to userspace.
116 *
117 * A quick note on symbol prefixes:
118 * - "xfs_" are general XFS symbols.
119 * - "xchk_" are symbols related to metadata checking.
120 * - "xrep_" are symbols related to metadata repair.
121 * - "xfs_scrub_" are symbols that tie online fsck to the rest of XFS.
122 */
123
124/*
125 * Scrub probe -- userspace uses this to probe if we're willing to scrub
126 * or repair a given mountpoint. This will be used by xfs_scrub to
127 * probe the kernel's abilities to scrub (and repair) the metadata. We
128 * do this by validating the ioctl inputs from userspace, preparing the
129 * filesystem for a scrub (or a repair) operation, and immediately
130 * returning to userspace. Userspace can use the returned errno and
131 * structure state to decide (in broad terms) if scrub/repair are
132 * supported by the running kernel.
133 */
134static int
135xchk_probe(
136 struct xfs_scrub *sc)
137{
138 int error = 0;
139
140 if (xchk_should_terminate(sc, &error))
141 return error;
142
143 return 0;
144}
145
146/* Scrub setup and teardown */
147
148/* Free all the resources and finish the transactions. */
149STATIC int
150xchk_teardown(
151 struct xfs_scrub *sc,
152 int error)
153{
154 struct xfs_inode *ip_in = XFS_I(file_inode(sc->file));
155
156 xchk_ag_free(sc, &sc->sa);
157 if (sc->tp) {
158 if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR))
159 error = xfs_trans_commit(sc->tp);
160 else
161 xfs_trans_cancel(sc->tp);
162 sc->tp = NULL;
163 }
164 if (sc->ip) {
165 if (sc->ilock_flags)
166 xfs_iunlock(sc->ip, sc->ilock_flags);
167 if (sc->ip != ip_in &&
168 !xfs_internal_inum(sc->mp, sc->ip->i_ino))
169 xfs_irele(sc->ip);
170 sc->ip = NULL;
171 }
172 if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)
173 mnt_drop_write_file(sc->file);
174 if (sc->flags & XCHK_REAPING_DISABLED)
175 xchk_start_reaping(sc);
176 if (sc->flags & XCHK_HAS_QUOTAOFFLOCK) {
177 mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
178 sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK;
179 }
180 if (sc->buf) {
181 kmem_free(sc->buf);
182 sc->buf = NULL;
183 }
184 return error;
185}
186
187/* Scrubbing dispatch. */
188
189static const struct xchk_meta_ops meta_scrub_ops[] = {
190 [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */
191 .type = ST_NONE,
192 .setup = xchk_setup_fs,
193 .scrub = xchk_probe,
194 .repair = xrep_probe,
195 },
196 [XFS_SCRUB_TYPE_SB] = { /* superblock */
197 .type = ST_PERAG,
198 .setup = xchk_setup_fs,
199 .scrub = xchk_superblock,
200 .repair = xrep_superblock,
201 },
202 [XFS_SCRUB_TYPE_AGF] = { /* agf */
203 .type = ST_PERAG,
204 .setup = xchk_setup_fs,
205 .scrub = xchk_agf,
206 .repair = xrep_agf,
207 },
208 [XFS_SCRUB_TYPE_AGFL]= { /* agfl */
209 .type = ST_PERAG,
210 .setup = xchk_setup_fs,
211 .scrub = xchk_agfl,
212 .repair = xrep_agfl,
213 },
214 [XFS_SCRUB_TYPE_AGI] = { /* agi */
215 .type = ST_PERAG,
216 .setup = xchk_setup_fs,
217 .scrub = xchk_agi,
218 .repair = xrep_agi,
219 },
220 [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */
221 .type = ST_PERAG,
222 .setup = xchk_setup_ag_allocbt,
223 .scrub = xchk_bnobt,
224 .repair = xrep_notsupported,
225 },
226 [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */
227 .type = ST_PERAG,
228 .setup = xchk_setup_ag_allocbt,
229 .scrub = xchk_cntbt,
230 .repair = xrep_notsupported,
231 },
232 [XFS_SCRUB_TYPE_INOBT] = { /* inobt */
233 .type = ST_PERAG,
234 .setup = xchk_setup_ag_iallocbt,
235 .scrub = xchk_inobt,
236 .repair = xrep_notsupported,
237 },
238 [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */
239 .type = ST_PERAG,
240 .setup = xchk_setup_ag_iallocbt,
241 .scrub = xchk_finobt,
242 .has = xfs_sb_version_hasfinobt,
243 .repair = xrep_notsupported,
244 },
245 [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */
246 .type = ST_PERAG,
247 .setup = xchk_setup_ag_rmapbt,
248 .scrub = xchk_rmapbt,
249 .has = xfs_sb_version_hasrmapbt,
250 .repair = xrep_notsupported,
251 },
252 [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */
253 .type = ST_PERAG,
254 .setup = xchk_setup_ag_refcountbt,
255 .scrub = xchk_refcountbt,
256 .has = xfs_sb_version_hasreflink,
257 .repair = xrep_notsupported,
258 },
259 [XFS_SCRUB_TYPE_INODE] = { /* inode record */
260 .type = ST_INODE,
261 .setup = xchk_setup_inode,
262 .scrub = xchk_inode,
263 .repair = xrep_notsupported,
264 },
265 [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */
266 .type = ST_INODE,
267 .setup = xchk_setup_inode_bmap,
268 .scrub = xchk_bmap_data,
269 .repair = xrep_notsupported,
270 },
271 [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */
272 .type = ST_INODE,
273 .setup = xchk_setup_inode_bmap,
274 .scrub = xchk_bmap_attr,
275 .repair = xrep_notsupported,
276 },
277 [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */
278 .type = ST_INODE,
279 .setup = xchk_setup_inode_bmap,
280 .scrub = xchk_bmap_cow,
281 .repair = xrep_notsupported,
282 },
283 [XFS_SCRUB_TYPE_DIR] = { /* directory */
284 .type = ST_INODE,
285 .setup = xchk_setup_directory,
286 .scrub = xchk_directory,
287 .repair = xrep_notsupported,
288 },
289 [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */
290 .type = ST_INODE,
291 .setup = xchk_setup_xattr,
292 .scrub = xchk_xattr,
293 .repair = xrep_notsupported,
294 },
295 [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */
296 .type = ST_INODE,
297 .setup = xchk_setup_symlink,
298 .scrub = xchk_symlink,
299 .repair = xrep_notsupported,
300 },
301 [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */
302 .type = ST_INODE,
303 .setup = xchk_setup_parent,
304 .scrub = xchk_parent,
305 .repair = xrep_notsupported,
306 },
307 [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */
308 .type = ST_FS,
309 .setup = xchk_setup_rt,
310 .scrub = xchk_rtbitmap,
311 .has = xfs_sb_version_hasrealtime,
312 .repair = xrep_notsupported,
313 },
314 [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */
315 .type = ST_FS,
316 .setup = xchk_setup_rt,
317 .scrub = xchk_rtsummary,
318 .has = xfs_sb_version_hasrealtime,
319 .repair = xrep_notsupported,
320 },
321 [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */
322 .type = ST_FS,
323 .setup = xchk_setup_quota,
324 .scrub = xchk_quota,
325 .repair = xrep_notsupported,
326 },
327 [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */
328 .type = ST_FS,
329 .setup = xchk_setup_quota,
330 .scrub = xchk_quota,
331 .repair = xrep_notsupported,
332 },
333 [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */
334 .type = ST_FS,
335 .setup = xchk_setup_quota,
336 .scrub = xchk_quota,
337 .repair = xrep_notsupported,
338 },
339 [XFS_SCRUB_TYPE_FSCOUNTERS] = { /* fs summary counters */
340 .type = ST_FS,
341 .setup = xchk_setup_fscounters,
342 .scrub = xchk_fscounters,
343 .repair = xrep_notsupported,
344 },
345};
346
347/* This isn't a stable feature, warn once per day. */
348static inline void
349xchk_experimental_warning(
350 struct xfs_mount *mp)
351{
352 static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT(
353 "xchk_warning", 86400 * HZ, 1);
354 ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE);
355
356 if (__ratelimit(&scrub_warning))
357 xfs_alert(mp,
358"EXPERIMENTAL online scrub feature in use. Use at your own risk!");
359}
360
361static int
362xchk_validate_inputs(
363 struct xfs_mount *mp,
364 struct xfs_scrub_metadata *sm)
365{
366 int error;
367 const struct xchk_meta_ops *ops;
368
369 error = -EINVAL;
370 /* Check our inputs. */
371 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT;
372 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN)
373 goto out;
374 /* sm_reserved[] must be zero */
375 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved)))
376 goto out;
377
378 error = -ENOENT;
379 /* Do we know about this type of metadata? */
380 if (sm->sm_type >= XFS_SCRUB_TYPE_NR)
381 goto out;
382 ops = &meta_scrub_ops[sm->sm_type];
383 if (ops->setup == NULL || ops->scrub == NULL)
384 goto out;
385 /* Does this fs even support this type of metadata? */
386 if (ops->has && !ops->has(&mp->m_sb))
387 goto out;
388
389 error = -EINVAL;
390 /* restricting fields must be appropriate for type */
391 switch (ops->type) {
392 case ST_NONE:
393 case ST_FS:
394 if (sm->sm_ino || sm->sm_gen || sm->sm_agno)
395 goto out;
396 break;
397 case ST_PERAG:
398 if (sm->sm_ino || sm->sm_gen ||
399 sm->sm_agno >= mp->m_sb.sb_agcount)
400 goto out;
401 break;
402 case ST_INODE:
403 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino))
404 goto out;
405 break;
406 default:
407 goto out;
408 }
409
410 /*
411 * We only want to repair read-write v5+ filesystems. Defer the check
412 * for ops->repair until after our scrub confirms that we need to
413 * perform repairs so that we avoid failing due to not supporting
414 * repairing an object that doesn't need repairs.
415 */
416 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) {
417 error = -EOPNOTSUPP;
418 if (!xfs_sb_version_hascrc(&mp->m_sb))
419 goto out;
420
421 error = -EROFS;
422 if (mp->m_flags & XFS_MOUNT_RDONLY)
423 goto out;
424 }
425
426 error = 0;
427out:
428 return error;
429}
430
431#ifdef CONFIG_XFS_ONLINE_REPAIR
432static inline void xchk_postmortem(struct xfs_scrub *sc)
433{
434 /*
435 * Userspace asked us to repair something, we repaired it, rescanned
436 * it, and the rescan says it's still broken. Scream about this in
437 * the system logs.
438 */
439 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) &&
440 (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
441 XFS_SCRUB_OFLAG_XCORRUPT)))
442 xrep_failure(sc->mp);
443}
444#else
445static inline void xchk_postmortem(struct xfs_scrub *sc)
446{
447 /*
448 * Userspace asked us to scrub something, it's broken, and we have no
449 * way of fixing it. Scream in the logs.
450 */
451 if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
452 XFS_SCRUB_OFLAG_XCORRUPT))
453 xfs_alert_ratelimited(sc->mp,
454 "Corruption detected during scrub.");
455}
456#endif /* CONFIG_XFS_ONLINE_REPAIR */
457
458/* Dispatch metadata scrubbing. */
459int
460xfs_scrub_metadata(
461 struct file *file,
462 struct xfs_scrub_metadata *sm)
463{
464 struct xfs_scrub sc = {
465 .file = file,
466 .sm = sm,
467 .sa = {
468 .agno = NULLAGNUMBER,
469 },
470 };
471 struct xfs_mount *mp = XFS_I(file_inode(file))->i_mount;
472 int error = 0;
473
474 sc.mp = mp;
475
476 BUILD_BUG_ON(sizeof(meta_scrub_ops) !=
477 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR));
478
479 trace_xchk_start(XFS_I(file_inode(file)), sm, error);
480
481 /* Forbidden if we are shut down or mounted norecovery. */
482 error = -ESHUTDOWN;
483 if (XFS_FORCED_SHUTDOWN(mp))
484 goto out;
485 error = -ENOTRECOVERABLE;
486 if (mp->m_flags & XFS_MOUNT_NORECOVERY)
487 goto out;
488
489 error = xchk_validate_inputs(mp, sm);
490 if (error)
491 goto out;
492
493 xchk_experimental_warning(mp);
494
495 sc.ops = &meta_scrub_ops[sm->sm_type];
496 sc.sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type);
497retry_op:
498 /*
499 * When repairs are allowed, prevent freezing or readonly remount while
500 * scrub is running with a real transaction.
501 */
502 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) {
503 error = mnt_want_write_file(sc.file);
504 if (error)
505 goto out;
506 }
507
508 /* Set up for the operation. */
509 error = sc.ops->setup(&sc);
510 if (error)
511 goto out_teardown;
512
513 /* Scrub for errors. */
514 error = sc.ops->scrub(&sc);
515 if (!(sc.flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) {
516 /*
517 * Scrubbers return -EDEADLOCK to mean 'try harder'.
518 * Tear down everything we hold, then set up again with
519 * preparation for worst-case scenarios.
520 */
521 error = xchk_teardown(&sc, 0);
522 if (error)
523 goto out;
524 sc.flags |= XCHK_TRY_HARDER;
525 goto retry_op;
526 } else if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE))
527 goto out_teardown;
528
529 xchk_update_health(&sc);
530
531 if ((sc.sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) &&
532 !(sc.flags & XREP_ALREADY_FIXED)) {
533 bool needs_fix;
534
535 /* Let debug users force us into the repair routines. */
536 if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR))
537 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
538
539 needs_fix = (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT |
540 XFS_SCRUB_OFLAG_XCORRUPT |
541 XFS_SCRUB_OFLAG_PREEN));
542 /*
543 * If userspace asked for a repair but it wasn't necessary,
544 * report that back to userspace.
545 */
546 if (!needs_fix) {
547 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED;
548 goto out_nofix;
549 }
550
551 /*
552 * If it's broken, userspace wants us to fix it, and we haven't
553 * already tried to fix it, then attempt a repair.
554 */
555 error = xrep_attempt(&sc);
556 if (error == -EAGAIN) {
557 /*
558 * Either the repair function succeeded or it couldn't
559 * get all the resources it needs; either way, we go
560 * back to the beginning and call the scrub function.
561 */
562 error = xchk_teardown(&sc, 0);
563 if (error) {
564 xrep_failure(mp);
565 goto out;
566 }
567 goto retry_op;
568 }
569 }
570
571out_nofix:
572 xchk_postmortem(&sc);
573out_teardown:
574 error = xchk_teardown(&sc, error);
575out:
576 trace_xchk_done(XFS_I(file_inode(file)), sm, error);
577 if (error == -EFSCORRUPTED || error == -EFSBADCRC) {
578 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT;
579 error = 0;
580 }
581 return error;
582}