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 "scrub/scrub.h" 19 #include "scrub/common.h" 20 #include "scrub/trace.h" 21 #include "scrub/repair.h" 22 #include "scrub/health.h" 23 #include "scrub/stats.h" 24 #include "scrub/xfile.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 */ 134 static int 135 xchk_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 static inline void 149 xchk_fsgates_disable( 150 struct xfs_scrub *sc) 151 { 152 if (!(sc->flags & XCHK_FSGATES_ALL)) 153 return; 154 155 trace_xchk_fsgates_disable(sc, sc->flags & XCHK_FSGATES_ALL); 156 157 if (sc->flags & XCHK_FSGATES_DRAIN) 158 xfs_drain_wait_disable(); 159 160 sc->flags &= ~XCHK_FSGATES_ALL; 161 } 162 163 /* Free all the resources and finish the transactions. */ 164 STATIC int 165 xchk_teardown( 166 struct xfs_scrub *sc, 167 int error) 168 { 169 xchk_ag_free(sc, &sc->sa); 170 if (sc->tp) { 171 if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) 172 error = xfs_trans_commit(sc->tp); 173 else 174 xfs_trans_cancel(sc->tp); 175 sc->tp = NULL; 176 } 177 if (sc->ip) { 178 if (sc->ilock_flags) 179 xchk_iunlock(sc, sc->ilock_flags); 180 xchk_irele(sc, sc->ip); 181 sc->ip = NULL; 182 } 183 if (sc->flags & XCHK_HAVE_FREEZE_PROT) { 184 sc->flags &= ~XCHK_HAVE_FREEZE_PROT; 185 mnt_drop_write_file(sc->file); 186 } 187 if (sc->xfile) { 188 xfile_destroy(sc->xfile); 189 sc->xfile = NULL; 190 } 191 if (sc->buf) { 192 if (sc->buf_cleanup) 193 sc->buf_cleanup(sc->buf); 194 kvfree(sc->buf); 195 sc->buf_cleanup = NULL; 196 sc->buf = NULL; 197 } 198 199 xchk_fsgates_disable(sc); 200 return error; 201 } 202 203 /* Scrubbing dispatch. */ 204 205 static const struct xchk_meta_ops meta_scrub_ops[] = { 206 [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */ 207 .type = ST_NONE, 208 .setup = xchk_setup_fs, 209 .scrub = xchk_probe, 210 .repair = xrep_probe, 211 }, 212 [XFS_SCRUB_TYPE_SB] = { /* superblock */ 213 .type = ST_PERAG, 214 .setup = xchk_setup_agheader, 215 .scrub = xchk_superblock, 216 .repair = xrep_superblock, 217 }, 218 [XFS_SCRUB_TYPE_AGF] = { /* agf */ 219 .type = ST_PERAG, 220 .setup = xchk_setup_agheader, 221 .scrub = xchk_agf, 222 .repair = xrep_agf, 223 }, 224 [XFS_SCRUB_TYPE_AGFL]= { /* agfl */ 225 .type = ST_PERAG, 226 .setup = xchk_setup_agheader, 227 .scrub = xchk_agfl, 228 .repair = xrep_agfl, 229 }, 230 [XFS_SCRUB_TYPE_AGI] = { /* agi */ 231 .type = ST_PERAG, 232 .setup = xchk_setup_agheader, 233 .scrub = xchk_agi, 234 .repair = xrep_agi, 235 }, 236 [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */ 237 .type = ST_PERAG, 238 .setup = xchk_setup_ag_allocbt, 239 .scrub = xchk_allocbt, 240 .repair = xrep_allocbt, 241 .repair_eval = xrep_revalidate_allocbt, 242 }, 243 [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */ 244 .type = ST_PERAG, 245 .setup = xchk_setup_ag_allocbt, 246 .scrub = xchk_allocbt, 247 .repair = xrep_allocbt, 248 .repair_eval = xrep_revalidate_allocbt, 249 }, 250 [XFS_SCRUB_TYPE_INOBT] = { /* inobt */ 251 .type = ST_PERAG, 252 .setup = xchk_setup_ag_iallocbt, 253 .scrub = xchk_iallocbt, 254 .repair = xrep_iallocbt, 255 .repair_eval = xrep_revalidate_iallocbt, 256 }, 257 [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */ 258 .type = ST_PERAG, 259 .setup = xchk_setup_ag_iallocbt, 260 .scrub = xchk_iallocbt, 261 .has = xfs_has_finobt, 262 .repair = xrep_iallocbt, 263 .repair_eval = xrep_revalidate_iallocbt, 264 }, 265 [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */ 266 .type = ST_PERAG, 267 .setup = xchk_setup_ag_rmapbt, 268 .scrub = xchk_rmapbt, 269 .has = xfs_has_rmapbt, 270 .repair = xrep_notsupported, 271 }, 272 [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */ 273 .type = ST_PERAG, 274 .setup = xchk_setup_ag_refcountbt, 275 .scrub = xchk_refcountbt, 276 .has = xfs_has_reflink, 277 .repair = xrep_refcountbt, 278 }, 279 [XFS_SCRUB_TYPE_INODE] = { /* inode record */ 280 .type = ST_INODE, 281 .setup = xchk_setup_inode, 282 .scrub = xchk_inode, 283 .repair = xrep_inode, 284 }, 285 [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */ 286 .type = ST_INODE, 287 .setup = xchk_setup_inode_bmap, 288 .scrub = xchk_bmap_data, 289 .repair = xrep_bmap_data, 290 }, 291 [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */ 292 .type = ST_INODE, 293 .setup = xchk_setup_inode_bmap, 294 .scrub = xchk_bmap_attr, 295 .repair = xrep_bmap_attr, 296 }, 297 [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */ 298 .type = ST_INODE, 299 .setup = xchk_setup_inode_bmap, 300 .scrub = xchk_bmap_cow, 301 .repair = xrep_bmap_cow, 302 }, 303 [XFS_SCRUB_TYPE_DIR] = { /* directory */ 304 .type = ST_INODE, 305 .setup = xchk_setup_directory, 306 .scrub = xchk_directory, 307 .repair = xrep_notsupported, 308 }, 309 [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */ 310 .type = ST_INODE, 311 .setup = xchk_setup_xattr, 312 .scrub = xchk_xattr, 313 .repair = xrep_notsupported, 314 }, 315 [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */ 316 .type = ST_INODE, 317 .setup = xchk_setup_symlink, 318 .scrub = xchk_symlink, 319 .repair = xrep_notsupported, 320 }, 321 [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */ 322 .type = ST_INODE, 323 .setup = xchk_setup_parent, 324 .scrub = xchk_parent, 325 .repair = xrep_notsupported, 326 }, 327 [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */ 328 .type = ST_FS, 329 .setup = xchk_setup_rtbitmap, 330 .scrub = xchk_rtbitmap, 331 .repair = xrep_rtbitmap, 332 }, 333 [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */ 334 .type = ST_FS, 335 .setup = xchk_setup_rtsummary, 336 .scrub = xchk_rtsummary, 337 .repair = xrep_notsupported, 338 }, 339 [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */ 340 .type = ST_FS, 341 .setup = xchk_setup_quota, 342 .scrub = xchk_quota, 343 .repair = xrep_quota, 344 }, 345 [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */ 346 .type = ST_FS, 347 .setup = xchk_setup_quota, 348 .scrub = xchk_quota, 349 .repair = xrep_quota, 350 }, 351 [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */ 352 .type = ST_FS, 353 .setup = xchk_setup_quota, 354 .scrub = xchk_quota, 355 .repair = xrep_quota, 356 }, 357 [XFS_SCRUB_TYPE_FSCOUNTERS] = { /* fs summary counters */ 358 .type = ST_FS, 359 .setup = xchk_setup_fscounters, 360 .scrub = xchk_fscounters, 361 .repair = xrep_notsupported, 362 }, 363 }; 364 365 static int 366 xchk_validate_inputs( 367 struct xfs_mount *mp, 368 struct xfs_scrub_metadata *sm) 369 { 370 int error; 371 const struct xchk_meta_ops *ops; 372 373 error = -EINVAL; 374 /* Check our inputs. */ 375 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 376 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 377 goto out; 378 /* sm_reserved[] must be zero */ 379 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 380 goto out; 381 382 error = -ENOENT; 383 /* Do we know about this type of metadata? */ 384 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 385 goto out; 386 ops = &meta_scrub_ops[sm->sm_type]; 387 if (ops->setup == NULL || ops->scrub == NULL) 388 goto out; 389 /* Does this fs even support this type of metadata? */ 390 if (ops->has && !ops->has(mp)) 391 goto out; 392 393 error = -EINVAL; 394 /* restricting fields must be appropriate for type */ 395 switch (ops->type) { 396 case ST_NONE: 397 case ST_FS: 398 if (sm->sm_ino || sm->sm_gen || sm->sm_agno) 399 goto out; 400 break; 401 case ST_PERAG: 402 if (sm->sm_ino || sm->sm_gen || 403 sm->sm_agno >= mp->m_sb.sb_agcount) 404 goto out; 405 break; 406 case ST_INODE: 407 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) 408 goto out; 409 break; 410 default: 411 goto out; 412 } 413 414 /* No rebuild without repair. */ 415 if ((sm->sm_flags & XFS_SCRUB_IFLAG_FORCE_REBUILD) && 416 !(sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) 417 return -EINVAL; 418 419 /* 420 * We only want to repair read-write v5+ filesystems. Defer the check 421 * for ops->repair until after our scrub confirms that we need to 422 * perform repairs so that we avoid failing due to not supporting 423 * repairing an object that doesn't need repairs. 424 */ 425 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 426 error = -EOPNOTSUPP; 427 if (!xfs_has_crc(mp)) 428 goto out; 429 430 error = -EROFS; 431 if (xfs_is_readonly(mp)) 432 goto out; 433 } 434 435 error = 0; 436 out: 437 return error; 438 } 439 440 #ifdef CONFIG_XFS_ONLINE_REPAIR 441 static inline void xchk_postmortem(struct xfs_scrub *sc) 442 { 443 /* 444 * Userspace asked us to repair something, we repaired it, rescanned 445 * it, and the rescan says it's still broken. Scream about this in 446 * the system logs. 447 */ 448 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 449 (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 450 XFS_SCRUB_OFLAG_XCORRUPT))) 451 xrep_failure(sc->mp); 452 } 453 #else 454 static inline void xchk_postmortem(struct xfs_scrub *sc) 455 { 456 /* 457 * Userspace asked us to scrub something, it's broken, and we have no 458 * way of fixing it. Scream in the logs. 459 */ 460 if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 461 XFS_SCRUB_OFLAG_XCORRUPT)) 462 xfs_alert_ratelimited(sc->mp, 463 "Corruption detected during scrub."); 464 } 465 #endif /* CONFIG_XFS_ONLINE_REPAIR */ 466 467 /* Dispatch metadata scrubbing. */ 468 int 469 xfs_scrub_metadata( 470 struct file *file, 471 struct xfs_scrub_metadata *sm) 472 { 473 struct xchk_stats_run run = { }; 474 struct xfs_scrub *sc; 475 struct xfs_mount *mp = XFS_I(file_inode(file))->i_mount; 476 u64 check_start; 477 int error = 0; 478 479 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 480 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); 481 482 trace_xchk_start(XFS_I(file_inode(file)), sm, error); 483 484 /* Forbidden if we are shut down or mounted norecovery. */ 485 error = -ESHUTDOWN; 486 if (xfs_is_shutdown(mp)) 487 goto out; 488 error = -ENOTRECOVERABLE; 489 if (xfs_has_norecovery(mp)) 490 goto out; 491 492 error = xchk_validate_inputs(mp, sm); 493 if (error) 494 goto out; 495 496 xfs_warn_mount(mp, XFS_OPSTATE_WARNED_SCRUB, 497 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 498 499 sc = kzalloc(sizeof(struct xfs_scrub), XCHK_GFP_FLAGS); 500 if (!sc) { 501 error = -ENOMEM; 502 goto out; 503 } 504 505 sc->mp = mp; 506 sc->file = file; 507 sc->sm = sm; 508 sc->ops = &meta_scrub_ops[sm->sm_type]; 509 sc->sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); 510 retry_op: 511 /* 512 * When repairs are allowed, prevent freezing or readonly remount while 513 * scrub is running with a real transaction. 514 */ 515 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 516 error = mnt_want_write_file(sc->file); 517 if (error) 518 goto out_sc; 519 520 sc->flags |= XCHK_HAVE_FREEZE_PROT; 521 } 522 523 /* Set up for the operation. */ 524 error = sc->ops->setup(sc); 525 if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER)) 526 goto try_harder; 527 if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN)) 528 goto need_drain; 529 if (error) 530 goto out_teardown; 531 532 /* Scrub for errors. */ 533 check_start = xchk_stats_now(); 534 if ((sc->flags & XREP_ALREADY_FIXED) && sc->ops->repair_eval != NULL) 535 error = sc->ops->repair_eval(sc); 536 else 537 error = sc->ops->scrub(sc); 538 run.scrub_ns += xchk_stats_elapsed_ns(check_start); 539 if (error == -EDEADLOCK && !(sc->flags & XCHK_TRY_HARDER)) 540 goto try_harder; 541 if (error == -ECHRNG && !(sc->flags & XCHK_NEED_DRAIN)) 542 goto need_drain; 543 if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE)) 544 goto out_teardown; 545 546 xchk_update_health(sc); 547 548 if (xchk_could_repair(sc)) { 549 /* 550 * If userspace asked for a repair but it wasn't necessary, 551 * report that back to userspace. 552 */ 553 if (!xrep_will_attempt(sc)) { 554 sc->sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED; 555 goto out_nofix; 556 } 557 558 /* 559 * If it's broken, userspace wants us to fix it, and we haven't 560 * already tried to fix it, then attempt a repair. 561 */ 562 error = xrep_attempt(sc, &run); 563 if (error == -EAGAIN) { 564 /* 565 * Either the repair function succeeded or it couldn't 566 * get all the resources it needs; either way, we go 567 * back to the beginning and call the scrub function. 568 */ 569 error = xchk_teardown(sc, 0); 570 if (error) { 571 xrep_failure(mp); 572 goto out_sc; 573 } 574 goto retry_op; 575 } 576 } 577 578 out_nofix: 579 xchk_postmortem(sc); 580 out_teardown: 581 error = xchk_teardown(sc, error); 582 out_sc: 583 if (error != -ENOENT) 584 xchk_stats_merge(mp, sm, &run); 585 kfree(sc); 586 out: 587 trace_xchk_done(XFS_I(file_inode(file)), sm, error); 588 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 589 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 590 error = 0; 591 } 592 return error; 593 need_drain: 594 error = xchk_teardown(sc, 0); 595 if (error) 596 goto out_sc; 597 sc->flags |= XCHK_NEED_DRAIN; 598 run.retries++; 599 goto retry_op; 600 try_harder: 601 /* 602 * Scrubbers return -EDEADLOCK to mean 'try harder'. Tear down 603 * everything we hold, then set up again with preparation for 604 * worst-case scenarios. 605 */ 606 error = xchk_teardown(sc, 0); 607 if (error) 608 goto out_sc; 609 sc->flags |= XCHK_TRY_HARDER; 610 run.retries++; 611 goto retry_op; 612 } 613