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 "scrub/scrub.h" 20 #include "scrub/common.h" 21 #include "scrub/trace.h" 22 #include "scrub/repair.h" 23 #include "scrub/health.h" 24 25 /* 26 * Online Scrub and Repair 27 * 28 * Traditionally, XFS (the kernel driver) did not know how to check or 29 * repair on-disk data structures. That task was left to the xfs_check 30 * and xfs_repair tools, both of which require taking the filesystem 31 * offline for a thorough but time consuming examination. Online 32 * scrub & repair, on the other hand, enables us to check the metadata 33 * for obvious errors while carefully stepping around the filesystem's 34 * ongoing operations, locking rules, etc. 35 * 36 * Given that most XFS metadata consist of records stored in a btree, 37 * most of the checking functions iterate the btree blocks themselves 38 * looking for irregularities. When a record block is encountered, each 39 * record can be checked for obviously bad values. Record values can 40 * also be cross-referenced against other btrees to look for potential 41 * misunderstandings between pieces of metadata. 42 * 43 * It is expected that the checkers responsible for per-AG metadata 44 * structures will lock the AG headers (AGI, AGF, AGFL), iterate the 45 * metadata structure, and perform any relevant cross-referencing before 46 * unlocking the AG and returning the results to userspace. These 47 * scrubbers must not keep an AG locked for too long to avoid tying up 48 * the block and inode allocators. 49 * 50 * Block maps and b-trees rooted in an inode present a special challenge 51 * because they can involve extents from any AG. The general scrubber 52 * structure of lock -> check -> xref -> unlock still holds, but AG 53 * locking order rules /must/ be obeyed to avoid deadlocks. The 54 * ordering rule, of course, is that we must lock in increasing AG 55 * order. Helper functions are provided to track which AG headers we've 56 * already locked. If we detect an imminent locking order violation, we 57 * can signal a potential deadlock, in which case the scrubber can jump 58 * out to the top level, lock all the AGs in order, and retry the scrub. 59 * 60 * For file data (directories, extended attributes, symlinks) scrub, we 61 * can simply lock the inode and walk the data. For btree data 62 * (directories and attributes) we follow the same btree-scrubbing 63 * strategy outlined previously to check the records. 64 * 65 * We use a bit of trickery with transactions to avoid buffer deadlocks 66 * if there is a cycle in the metadata. The basic problem is that 67 * travelling down a btree involves locking the current buffer at each 68 * tree level. If a pointer should somehow point back to a buffer that 69 * we've already examined, we will deadlock due to the second buffer 70 * locking attempt. Note however that grabbing a buffer in transaction 71 * context links the locked buffer to the transaction. If we try to 72 * re-grab the buffer in the context of the same transaction, we avoid 73 * the second lock attempt and continue. Between the verifier and the 74 * scrubber, something will notice that something is amiss and report 75 * the corruption. Therefore, each scrubber will allocate an empty 76 * transaction, attach buffers to it, and cancel the transaction at the 77 * end of the scrub run. Cancelling a non-dirty transaction simply 78 * unlocks the buffers. 79 * 80 * There are four pieces of data that scrub can communicate to 81 * userspace. The first is the error code (errno), which can be used to 82 * communicate operational errors in performing the scrub. There are 83 * also three flags that can be set in the scrub context. If the data 84 * structure itself is corrupt, the CORRUPT flag will be set. If 85 * the metadata is correct but otherwise suboptimal, the PREEN flag 86 * will be set. 87 * 88 * We perform secondary validation of filesystem metadata by 89 * cross-referencing every record with all other available metadata. 90 * For example, for block mapping extents, we verify that there are no 91 * records in the free space and inode btrees corresponding to that 92 * space extent and that there is a corresponding entry in the reverse 93 * mapping btree. Inconsistent metadata is noted by setting the 94 * XCORRUPT flag; btree query function errors are noted by setting the 95 * XFAIL flag and deleting the cursor to prevent further attempts to 96 * cross-reference with a defective btree. 97 * 98 * If a piece of metadata proves corrupt or suboptimal, the userspace 99 * program can ask the kernel to apply some tender loving care (TLC) to 100 * the metadata object by setting the REPAIR flag and re-calling the 101 * scrub ioctl. "Corruption" is defined by metadata violating the 102 * on-disk specification; operations cannot continue if the violation is 103 * left untreated. It is possible for XFS to continue if an object is 104 * "suboptimal", however performance may be degraded. Repairs are 105 * usually performed by rebuilding the metadata entirely out of 106 * redundant metadata. Optimizing, on the other hand, can sometimes be 107 * done without rebuilding entire structures. 108 * 109 * Generally speaking, the repair code has the following code structure: 110 * Lock -> scrub -> repair -> commit -> re-lock -> re-scrub -> unlock. 111 * The first check helps us figure out if we need to rebuild or simply 112 * optimize the structure so that the rebuild knows what to do. The 113 * second check evaluates the completeness of the repair; that is what 114 * is reported to userspace. 115 * 116 * A quick note on symbol prefixes: 117 * - "xfs_" are general XFS symbols. 118 * - "xchk_" are symbols related to metadata checking. 119 * - "xrep_" are symbols related to metadata repair. 120 * - "xfs_scrub_" are symbols that tie online fsck to the rest of XFS. 121 */ 122 123 /* 124 * Scrub probe -- userspace uses this to probe if we're willing to scrub 125 * or repair a given mountpoint. This will be used by xfs_scrub to 126 * probe the kernel's abilities to scrub (and repair) the metadata. We 127 * do this by validating the ioctl inputs from userspace, preparing the 128 * filesystem for a scrub (or a repair) operation, and immediately 129 * returning to userspace. Userspace can use the returned errno and 130 * structure state to decide (in broad terms) if scrub/repair are 131 * supported by the running kernel. 132 */ 133 static int 134 xchk_probe( 135 struct xfs_scrub *sc) 136 { 137 int error = 0; 138 139 if (xchk_should_terminate(sc, &error)) 140 return error; 141 142 return 0; 143 } 144 145 /* Scrub setup and teardown */ 146 147 /* Free all the resources and finish the transactions. */ 148 STATIC int 149 xchk_teardown( 150 struct xfs_scrub *sc, 151 struct xfs_inode *ip_in, 152 int error) 153 { 154 xchk_ag_free(sc, &sc->sa); 155 if (sc->tp) { 156 if (error == 0 && (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)) 157 error = xfs_trans_commit(sc->tp); 158 else 159 xfs_trans_cancel(sc->tp); 160 sc->tp = NULL; 161 } 162 if (sc->ip) { 163 if (sc->ilock_flags) 164 xfs_iunlock(sc->ip, sc->ilock_flags); 165 if (sc->ip != ip_in && 166 !xfs_internal_inum(sc->mp, sc->ip->i_ino)) 167 xfs_irele(sc->ip); 168 sc->ip = NULL; 169 } 170 if (sc->flags & XCHK_REAPING_DISABLED) 171 xchk_start_reaping(sc); 172 if (sc->flags & XCHK_HAS_QUOTAOFFLOCK) { 173 mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock); 174 sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK; 175 } 176 if (sc->buf) { 177 kmem_free(sc->buf); 178 sc->buf = NULL; 179 } 180 return error; 181 } 182 183 /* Scrubbing dispatch. */ 184 185 static const struct xchk_meta_ops meta_scrub_ops[] = { 186 [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */ 187 .type = ST_NONE, 188 .setup = xchk_setup_fs, 189 .scrub = xchk_probe, 190 .repair = xrep_probe, 191 }, 192 [XFS_SCRUB_TYPE_SB] = { /* superblock */ 193 .type = ST_PERAG, 194 .setup = xchk_setup_fs, 195 .scrub = xchk_superblock, 196 .repair = xrep_superblock, 197 }, 198 [XFS_SCRUB_TYPE_AGF] = { /* agf */ 199 .type = ST_PERAG, 200 .setup = xchk_setup_fs, 201 .scrub = xchk_agf, 202 .repair = xrep_agf, 203 }, 204 [XFS_SCRUB_TYPE_AGFL]= { /* agfl */ 205 .type = ST_PERAG, 206 .setup = xchk_setup_fs, 207 .scrub = xchk_agfl, 208 .repair = xrep_agfl, 209 }, 210 [XFS_SCRUB_TYPE_AGI] = { /* agi */ 211 .type = ST_PERAG, 212 .setup = xchk_setup_fs, 213 .scrub = xchk_agi, 214 .repair = xrep_agi, 215 }, 216 [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */ 217 .type = ST_PERAG, 218 .setup = xchk_setup_ag_allocbt, 219 .scrub = xchk_bnobt, 220 .repair = xrep_notsupported, 221 }, 222 [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */ 223 .type = ST_PERAG, 224 .setup = xchk_setup_ag_allocbt, 225 .scrub = xchk_cntbt, 226 .repair = xrep_notsupported, 227 }, 228 [XFS_SCRUB_TYPE_INOBT] = { /* inobt */ 229 .type = ST_PERAG, 230 .setup = xchk_setup_ag_iallocbt, 231 .scrub = xchk_inobt, 232 .repair = xrep_notsupported, 233 }, 234 [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */ 235 .type = ST_PERAG, 236 .setup = xchk_setup_ag_iallocbt, 237 .scrub = xchk_finobt, 238 .has = xfs_sb_version_hasfinobt, 239 .repair = xrep_notsupported, 240 }, 241 [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */ 242 .type = ST_PERAG, 243 .setup = xchk_setup_ag_rmapbt, 244 .scrub = xchk_rmapbt, 245 .has = xfs_sb_version_hasrmapbt, 246 .repair = xrep_notsupported, 247 }, 248 [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */ 249 .type = ST_PERAG, 250 .setup = xchk_setup_ag_refcountbt, 251 .scrub = xchk_refcountbt, 252 .has = xfs_sb_version_hasreflink, 253 .repair = xrep_notsupported, 254 }, 255 [XFS_SCRUB_TYPE_INODE] = { /* inode record */ 256 .type = ST_INODE, 257 .setup = xchk_setup_inode, 258 .scrub = xchk_inode, 259 .repair = xrep_notsupported, 260 }, 261 [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */ 262 .type = ST_INODE, 263 .setup = xchk_setup_inode_bmap, 264 .scrub = xchk_bmap_data, 265 .repair = xrep_notsupported, 266 }, 267 [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */ 268 .type = ST_INODE, 269 .setup = xchk_setup_inode_bmap, 270 .scrub = xchk_bmap_attr, 271 .repair = xrep_notsupported, 272 }, 273 [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */ 274 .type = ST_INODE, 275 .setup = xchk_setup_inode_bmap, 276 .scrub = xchk_bmap_cow, 277 .repair = xrep_notsupported, 278 }, 279 [XFS_SCRUB_TYPE_DIR] = { /* directory */ 280 .type = ST_INODE, 281 .setup = xchk_setup_directory, 282 .scrub = xchk_directory, 283 .repair = xrep_notsupported, 284 }, 285 [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */ 286 .type = ST_INODE, 287 .setup = xchk_setup_xattr, 288 .scrub = xchk_xattr, 289 .repair = xrep_notsupported, 290 }, 291 [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */ 292 .type = ST_INODE, 293 .setup = xchk_setup_symlink, 294 .scrub = xchk_symlink, 295 .repair = xrep_notsupported, 296 }, 297 [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */ 298 .type = ST_INODE, 299 .setup = xchk_setup_parent, 300 .scrub = xchk_parent, 301 .repair = xrep_notsupported, 302 }, 303 [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */ 304 .type = ST_FS, 305 .setup = xchk_setup_rt, 306 .scrub = xchk_rtbitmap, 307 .has = xfs_sb_version_hasrealtime, 308 .repair = xrep_notsupported, 309 }, 310 [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */ 311 .type = ST_FS, 312 .setup = xchk_setup_rt, 313 .scrub = xchk_rtsummary, 314 .has = xfs_sb_version_hasrealtime, 315 .repair = xrep_notsupported, 316 }, 317 [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */ 318 .type = ST_FS, 319 .setup = xchk_setup_quota, 320 .scrub = xchk_quota, 321 .repair = xrep_notsupported, 322 }, 323 [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */ 324 .type = ST_FS, 325 .setup = xchk_setup_quota, 326 .scrub = xchk_quota, 327 .repair = xrep_notsupported, 328 }, 329 [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */ 330 .type = ST_FS, 331 .setup = xchk_setup_quota, 332 .scrub = xchk_quota, 333 .repair = xrep_notsupported, 334 }, 335 [XFS_SCRUB_TYPE_FSCOUNTERS] = { /* fs summary counters */ 336 .type = ST_FS, 337 .setup = xchk_setup_fscounters, 338 .scrub = xchk_fscounters, 339 .repair = xrep_notsupported, 340 }, 341 }; 342 343 /* This isn't a stable feature, warn once per day. */ 344 static inline void 345 xchk_experimental_warning( 346 struct xfs_mount *mp) 347 { 348 static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT( 349 "xchk_warning", 86400 * HZ, 1); 350 ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE); 351 352 if (__ratelimit(&scrub_warning)) 353 xfs_alert(mp, 354 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 355 } 356 357 static int 358 xchk_validate_inputs( 359 struct xfs_mount *mp, 360 struct xfs_scrub_metadata *sm) 361 { 362 int error; 363 const struct xchk_meta_ops *ops; 364 365 error = -EINVAL; 366 /* Check our inputs. */ 367 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 368 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 369 goto out; 370 /* sm_reserved[] must be zero */ 371 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 372 goto out; 373 374 error = -ENOENT; 375 /* Do we know about this type of metadata? */ 376 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 377 goto out; 378 ops = &meta_scrub_ops[sm->sm_type]; 379 if (ops->setup == NULL || ops->scrub == NULL) 380 goto out; 381 /* Does this fs even support this type of metadata? */ 382 if (ops->has && !ops->has(&mp->m_sb)) 383 goto out; 384 385 error = -EINVAL; 386 /* restricting fields must be appropriate for type */ 387 switch (ops->type) { 388 case ST_NONE: 389 case ST_FS: 390 if (sm->sm_ino || sm->sm_gen || sm->sm_agno) 391 goto out; 392 break; 393 case ST_PERAG: 394 if (sm->sm_ino || sm->sm_gen || 395 sm->sm_agno >= mp->m_sb.sb_agcount) 396 goto out; 397 break; 398 case ST_INODE: 399 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) 400 goto out; 401 break; 402 default: 403 goto out; 404 } 405 406 /* 407 * We only want to repair read-write v5+ filesystems. Defer the check 408 * for ops->repair until after our scrub confirms that we need to 409 * perform repairs so that we avoid failing due to not supporting 410 * repairing an object that doesn't need repairs. 411 */ 412 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 413 error = -EOPNOTSUPP; 414 if (!xfs_sb_version_hascrc(&mp->m_sb)) 415 goto out; 416 417 error = -EROFS; 418 if (mp->m_flags & XFS_MOUNT_RDONLY) 419 goto out; 420 } 421 422 error = 0; 423 out: 424 return error; 425 } 426 427 #ifdef CONFIG_XFS_ONLINE_REPAIR 428 static inline void xchk_postmortem(struct xfs_scrub *sc) 429 { 430 /* 431 * Userspace asked us to repair something, we repaired it, rescanned 432 * it, and the rescan says it's still broken. Scream about this in 433 * the system logs. 434 */ 435 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 436 (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 437 XFS_SCRUB_OFLAG_XCORRUPT))) 438 xrep_failure(sc->mp); 439 } 440 #else 441 static inline void xchk_postmortem(struct xfs_scrub *sc) 442 { 443 /* 444 * Userspace asked us to scrub something, it's broken, and we have no 445 * way of fixing it. Scream in the logs. 446 */ 447 if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 448 XFS_SCRUB_OFLAG_XCORRUPT)) 449 xfs_alert_ratelimited(sc->mp, 450 "Corruption detected during scrub."); 451 } 452 #endif /* CONFIG_XFS_ONLINE_REPAIR */ 453 454 /* Dispatch metadata scrubbing. */ 455 int 456 xfs_scrub_metadata( 457 struct xfs_inode *ip, 458 struct xfs_scrub_metadata *sm) 459 { 460 struct xfs_scrub sc = { 461 .mp = ip->i_mount, 462 .sm = sm, 463 .sa = { 464 .agno = NULLAGNUMBER, 465 }, 466 }; 467 struct xfs_mount *mp = ip->i_mount; 468 int error = 0; 469 470 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 471 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); 472 473 trace_xchk_start(ip, sm, error); 474 475 /* Forbidden if we are shut down or mounted norecovery. */ 476 error = -ESHUTDOWN; 477 if (XFS_FORCED_SHUTDOWN(mp)) 478 goto out; 479 error = -ENOTRECOVERABLE; 480 if (mp->m_flags & XFS_MOUNT_NORECOVERY) 481 goto out; 482 483 error = xchk_validate_inputs(mp, sm); 484 if (error) 485 goto out; 486 487 xchk_experimental_warning(mp); 488 489 sc.ops = &meta_scrub_ops[sm->sm_type]; 490 sc.sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); 491 retry_op: 492 /* Set up for the operation. */ 493 error = sc.ops->setup(&sc, ip); 494 if (error) 495 goto out_teardown; 496 497 /* Scrub for errors. */ 498 error = sc.ops->scrub(&sc); 499 if (!(sc.flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) { 500 /* 501 * Scrubbers return -EDEADLOCK to mean 'try harder'. 502 * Tear down everything we hold, then set up again with 503 * preparation for worst-case scenarios. 504 */ 505 error = xchk_teardown(&sc, ip, 0); 506 if (error) 507 goto out; 508 sc.flags |= XCHK_TRY_HARDER; 509 goto retry_op; 510 } else if (error) 511 goto out_teardown; 512 513 xchk_update_health(&sc); 514 515 if ((sc.sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 516 !(sc.flags & XREP_ALREADY_FIXED)) { 517 bool needs_fix; 518 519 /* Let debug users force us into the repair routines. */ 520 if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) 521 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 522 523 needs_fix = (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 524 XFS_SCRUB_OFLAG_XCORRUPT | 525 XFS_SCRUB_OFLAG_PREEN)); 526 /* 527 * If userspace asked for a repair but it wasn't necessary, 528 * report that back to userspace. 529 */ 530 if (!needs_fix) { 531 sc.sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED; 532 goto out_nofix; 533 } 534 535 /* 536 * If it's broken, userspace wants us to fix it, and we haven't 537 * already tried to fix it, then attempt a repair. 538 */ 539 error = xrep_attempt(ip, &sc); 540 if (error == -EAGAIN) { 541 /* 542 * Either the repair function succeeded or it couldn't 543 * get all the resources it needs; either way, we go 544 * back to the beginning and call the scrub function. 545 */ 546 error = xchk_teardown(&sc, ip, 0); 547 if (error) { 548 xrep_failure(mp); 549 goto out; 550 } 551 goto retry_op; 552 } 553 } 554 555 out_nofix: 556 xchk_postmortem(&sc); 557 out_teardown: 558 error = xchk_teardown(&sc, ip, error); 559 out: 560 trace_xchk_done(ip, sm, error); 561 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 562 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 563 error = 0; 564 } 565 return error; 566 } 567