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 */ 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 /* Free all the resources and finish the transactions. */ 149 STATIC int 150 xchk_teardown( 151 struct xfs_scrub *sc, 152 struct xfs_inode *ip_in, 153 int error) 154 { 155 xchk_ag_free(sc, &sc->sa); 156 if (sc->tp) { 157 if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) 158 error = xfs_trans_commit(sc->tp); 159 else 160 xfs_trans_cancel(sc->tp); 161 sc->tp = NULL; 162 } 163 if (sc->ip) { 164 if (sc->ilock_flags) 165 xfs_iunlock(sc->ip, sc->ilock_flags); 166 if (sc->ip != ip_in && 167 !xfs_internal_inum(sc->mp, sc->ip->i_ino)) 168 xfs_irele(sc->ip); 169 sc->ip = NULL; 170 } 171 if (sc->flags & XCHK_REAPING_DISABLED) 172 xchk_start_reaping(sc); 173 if (sc->flags & XCHK_HAS_QUOTAOFFLOCK) { 174 mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock); 175 sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK; 176 } 177 if (sc->buf) { 178 kmem_free(sc->buf); 179 sc->buf = NULL; 180 } 181 return error; 182 } 183 184 /* Scrubbing dispatch. */ 185 186 static const struct xchk_meta_ops meta_scrub_ops[] = { 187 [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */ 188 .type = ST_NONE, 189 .setup = xchk_setup_fs, 190 .scrub = xchk_probe, 191 .repair = xrep_probe, 192 }, 193 [XFS_SCRUB_TYPE_SB] = { /* superblock */ 194 .type = ST_PERAG, 195 .setup = xchk_setup_fs, 196 .scrub = xchk_superblock, 197 .repair = xrep_superblock, 198 }, 199 [XFS_SCRUB_TYPE_AGF] = { /* agf */ 200 .type = ST_PERAG, 201 .setup = xchk_setup_fs, 202 .scrub = xchk_agf, 203 .repair = xrep_agf, 204 }, 205 [XFS_SCRUB_TYPE_AGFL]= { /* agfl */ 206 .type = ST_PERAG, 207 .setup = xchk_setup_fs, 208 .scrub = xchk_agfl, 209 .repair = xrep_agfl, 210 }, 211 [XFS_SCRUB_TYPE_AGI] = { /* agi */ 212 .type = ST_PERAG, 213 .setup = xchk_setup_fs, 214 .scrub = xchk_agi, 215 .repair = xrep_agi, 216 }, 217 [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */ 218 .type = ST_PERAG, 219 .setup = xchk_setup_ag_allocbt, 220 .scrub = xchk_bnobt, 221 .repair = xrep_notsupported, 222 }, 223 [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */ 224 .type = ST_PERAG, 225 .setup = xchk_setup_ag_allocbt, 226 .scrub = xchk_cntbt, 227 .repair = xrep_notsupported, 228 }, 229 [XFS_SCRUB_TYPE_INOBT] = { /* inobt */ 230 .type = ST_PERAG, 231 .setup = xchk_setup_ag_iallocbt, 232 .scrub = xchk_inobt, 233 .repair = xrep_notsupported, 234 }, 235 [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */ 236 .type = ST_PERAG, 237 .setup = xchk_setup_ag_iallocbt, 238 .scrub = xchk_finobt, 239 .has = xfs_sb_version_hasfinobt, 240 .repair = xrep_notsupported, 241 }, 242 [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */ 243 .type = ST_PERAG, 244 .setup = xchk_setup_ag_rmapbt, 245 .scrub = xchk_rmapbt, 246 .has = xfs_sb_version_hasrmapbt, 247 .repair = xrep_notsupported, 248 }, 249 [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */ 250 .type = ST_PERAG, 251 .setup = xchk_setup_ag_refcountbt, 252 .scrub = xchk_refcountbt, 253 .has = xfs_sb_version_hasreflink, 254 .repair = xrep_notsupported, 255 }, 256 [XFS_SCRUB_TYPE_INODE] = { /* inode record */ 257 .type = ST_INODE, 258 .setup = xchk_setup_inode, 259 .scrub = xchk_inode, 260 .repair = xrep_notsupported, 261 }, 262 [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */ 263 .type = ST_INODE, 264 .setup = xchk_setup_inode_bmap, 265 .scrub = xchk_bmap_data, 266 .repair = xrep_notsupported, 267 }, 268 [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */ 269 .type = ST_INODE, 270 .setup = xchk_setup_inode_bmap, 271 .scrub = xchk_bmap_attr, 272 .repair = xrep_notsupported, 273 }, 274 [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */ 275 .type = ST_INODE, 276 .setup = xchk_setup_inode_bmap, 277 .scrub = xchk_bmap_cow, 278 .repair = xrep_notsupported, 279 }, 280 [XFS_SCRUB_TYPE_DIR] = { /* directory */ 281 .type = ST_INODE, 282 .setup = xchk_setup_directory, 283 .scrub = xchk_directory, 284 .repair = xrep_notsupported, 285 }, 286 [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */ 287 .type = ST_INODE, 288 .setup = xchk_setup_xattr, 289 .scrub = xchk_xattr, 290 .repair = xrep_notsupported, 291 }, 292 [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */ 293 .type = ST_INODE, 294 .setup = xchk_setup_symlink, 295 .scrub = xchk_symlink, 296 .repair = xrep_notsupported, 297 }, 298 [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */ 299 .type = ST_INODE, 300 .setup = xchk_setup_parent, 301 .scrub = xchk_parent, 302 .repair = xrep_notsupported, 303 }, 304 [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */ 305 .type = ST_FS, 306 .setup = xchk_setup_rt, 307 .scrub = xchk_rtbitmap, 308 .has = xfs_sb_version_hasrealtime, 309 .repair = xrep_notsupported, 310 }, 311 [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */ 312 .type = ST_FS, 313 .setup = xchk_setup_rt, 314 .scrub = xchk_rtsummary, 315 .has = xfs_sb_version_hasrealtime, 316 .repair = xrep_notsupported, 317 }, 318 [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */ 319 .type = ST_FS, 320 .setup = xchk_setup_quota, 321 .scrub = xchk_quota, 322 .repair = xrep_notsupported, 323 }, 324 [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */ 325 .type = ST_FS, 326 .setup = xchk_setup_quota, 327 .scrub = xchk_quota, 328 .repair = xrep_notsupported, 329 }, 330 [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */ 331 .type = ST_FS, 332 .setup = xchk_setup_quota, 333 .scrub = xchk_quota, 334 .repair = xrep_notsupported, 335 }, 336 [XFS_SCRUB_TYPE_FSCOUNTERS] = { /* fs summary counters */ 337 .type = ST_FS, 338 .setup = xchk_setup_fscounters, 339 .scrub = xchk_fscounters, 340 .repair = xrep_notsupported, 341 }, 342 }; 343 344 /* This isn't a stable feature, warn once per day. */ 345 static inline void 346 xchk_experimental_warning( 347 struct xfs_mount *mp) 348 { 349 static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT( 350 "xchk_warning", 86400 * HZ, 1); 351 ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE); 352 353 if (__ratelimit(&scrub_warning)) 354 xfs_alert(mp, 355 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 356 } 357 358 static int 359 xchk_validate_inputs( 360 struct xfs_mount *mp, 361 struct xfs_scrub_metadata *sm) 362 { 363 int error; 364 const struct xchk_meta_ops *ops; 365 366 error = -EINVAL; 367 /* Check our inputs. */ 368 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 369 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 370 goto out; 371 /* sm_reserved[] must be zero */ 372 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 373 goto out; 374 375 error = -ENOENT; 376 /* Do we know about this type of metadata? */ 377 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 378 goto out; 379 ops = &meta_scrub_ops[sm->sm_type]; 380 if (ops->setup == NULL || ops->scrub == NULL) 381 goto out; 382 /* Does this fs even support this type of metadata? */ 383 if (ops->has && !ops->has(&mp->m_sb)) 384 goto out; 385 386 error = -EINVAL; 387 /* restricting fields must be appropriate for type */ 388 switch (ops->type) { 389 case ST_NONE: 390 case ST_FS: 391 if (sm->sm_ino || sm->sm_gen || sm->sm_agno) 392 goto out; 393 break; 394 case ST_PERAG: 395 if (sm->sm_ino || sm->sm_gen || 396 sm->sm_agno >= mp->m_sb.sb_agcount) 397 goto out; 398 break; 399 case ST_INODE: 400 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) 401 goto out; 402 break; 403 default: 404 goto out; 405 } 406 407 /* 408 * We only want to repair read-write v5+ filesystems. Defer the check 409 * for ops->repair until after our scrub confirms that we need to 410 * perform repairs so that we avoid failing due to not supporting 411 * repairing an object that doesn't need repairs. 412 */ 413 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 414 error = -EOPNOTSUPP; 415 if (!xfs_sb_version_hascrc(&mp->m_sb)) 416 goto out; 417 418 error = -EROFS; 419 if (mp->m_flags & XFS_MOUNT_RDONLY) 420 goto out; 421 } 422 423 error = 0; 424 out: 425 return error; 426 } 427 428 #ifdef CONFIG_XFS_ONLINE_REPAIR 429 static inline void xchk_postmortem(struct xfs_scrub *sc) 430 { 431 /* 432 * Userspace asked us to repair something, we repaired it, rescanned 433 * it, and the rescan says it's still broken. Scream about this in 434 * the system logs. 435 */ 436 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 437 (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 438 XFS_SCRUB_OFLAG_XCORRUPT))) 439 xrep_failure(sc->mp); 440 } 441 #else 442 static inline void xchk_postmortem(struct xfs_scrub *sc) 443 { 444 /* 445 * Userspace asked us to scrub something, it's broken, and we have no 446 * way of fixing it. Scream in the logs. 447 */ 448 if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 449 XFS_SCRUB_OFLAG_XCORRUPT)) 450 xfs_alert_ratelimited(sc->mp, 451 "Corruption detected during scrub."); 452 } 453 #endif /* CONFIG_XFS_ONLINE_REPAIR */ 454 455 /* Dispatch metadata scrubbing. */ 456 int 457 xfs_scrub_metadata( 458 struct xfs_inode *ip, 459 struct xfs_scrub_metadata *sm) 460 { 461 struct xfs_scrub sc = { 462 .mp = ip->i_mount, 463 .sm = sm, 464 .sa = { 465 .agno = NULLAGNUMBER, 466 }, 467 }; 468 struct xfs_mount *mp = ip->i_mount; 469 int error = 0; 470 471 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 472 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); 473 474 trace_xchk_start(ip, sm, error); 475 476 /* Forbidden if we are shut down or mounted norecovery. */ 477 error = -ESHUTDOWN; 478 if (XFS_FORCED_SHUTDOWN(mp)) 479 goto out; 480 error = -ENOTRECOVERABLE; 481 if (mp->m_flags & XFS_MOUNT_NORECOVERY) 482 goto out; 483 484 error = xchk_validate_inputs(mp, sm); 485 if (error) 486 goto out; 487 488 xchk_experimental_warning(mp); 489 490 sc.ops = &meta_scrub_ops[sm->sm_type]; 491 sc.sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); 492 retry_op: 493 /* Set up for the operation. */ 494 error = sc.ops->setup(&sc, ip); 495 if (error) 496 goto out_teardown; 497 498 /* Scrub for errors. */ 499 error = sc.ops->scrub(&sc); 500 if (!(sc.flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) { 501 /* 502 * Scrubbers return -EDEADLOCK to mean 'try harder'. 503 * Tear down everything we hold, then set up again with 504 * preparation for worst-case scenarios. 505 */ 506 error = xchk_teardown(&sc, ip, 0); 507 if (error) 508 goto out; 509 sc.flags |= XCHK_TRY_HARDER; 510 goto retry_op; 511 } else if (error) 512 goto out_teardown; 513 514 xchk_update_health(&sc); 515 516 if ((sc.sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 517 !(sc.flags & XREP_ALREADY_FIXED)) { 518 bool needs_fix; 519 520 /* Let debug users force us into the repair routines. */ 521 if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) 522 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 523 524 needs_fix = (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 525 XFS_SCRUB_OFLAG_XCORRUPT | 526 XFS_SCRUB_OFLAG_PREEN)); 527 /* 528 * If userspace asked for a repair but it wasn't necessary, 529 * report that back to userspace. 530 */ 531 if (!needs_fix) { 532 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED; 533 goto out_nofix; 534 } 535 536 /* 537 * If it's broken, userspace wants us to fix it, and we haven't 538 * already tried to fix it, then attempt a repair. 539 */ 540 error = xrep_attempt(ip, &sc); 541 if (error == -EAGAIN) { 542 /* 543 * Either the repair function succeeded or it couldn't 544 * get all the resources it needs; either way, we go 545 * back to the beginning and call the scrub function. 546 */ 547 error = xchk_teardown(&sc, ip, 0); 548 if (error) { 549 xrep_failure(mp); 550 goto out; 551 } 552 goto retry_op; 553 } 554 } 555 556 out_nofix: 557 xchk_postmortem(&sc); 558 out_teardown: 559 error = xchk_teardown(&sc, ip, error); 560 out: 561 trace_xchk_done(ip, sm, error); 562 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 563 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 564 error = 0; 565 } 566 return error; 567 } 568