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 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->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_has_finobt, 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_has_rmapbt, 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_has_reflink, 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_has_realtime, 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_has_realtime, 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)) 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_has_crc(mp)) 415 goto out; 416 417 error = -EROFS; 418 if (xfs_is_readonly(mp)) 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 file *file, 458 struct xfs_scrub_metadata *sm) 459 { 460 struct xfs_scrub *sc; 461 struct xfs_mount *mp = XFS_I(file_inode(file))->i_mount; 462 int error = 0; 463 464 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 465 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); 466 467 trace_xchk_start(XFS_I(file_inode(file)), sm, error); 468 469 /* Forbidden if we are shut down or mounted norecovery. */ 470 error = -ESHUTDOWN; 471 if (xfs_is_shutdown(mp)) 472 goto out; 473 error = -ENOTRECOVERABLE; 474 if (xfs_has_norecovery(mp)) 475 goto out; 476 477 error = xchk_validate_inputs(mp, sm); 478 if (error) 479 goto out; 480 481 xchk_experimental_warning(mp); 482 483 sc = kmem_zalloc(sizeof(struct xfs_scrub), KM_NOFS | KM_MAYFAIL); 484 if (!sc) { 485 error = -ENOMEM; 486 goto out; 487 } 488 489 sc->mp = mp; 490 sc->file = file; 491 sc->sm = sm; 492 sc->ops = &meta_scrub_ops[sm->sm_type]; 493 sc->sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); 494 retry_op: 495 /* 496 * When repairs are allowed, prevent freezing or readonly remount while 497 * scrub is running with a real transaction. 498 */ 499 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 500 error = mnt_want_write_file(sc->file); 501 if (error) 502 goto out_sc; 503 } 504 505 /* Set up for the operation. */ 506 error = sc->ops->setup(sc); 507 if (error) 508 goto out_teardown; 509 510 /* Scrub for errors. */ 511 error = sc->ops->scrub(sc); 512 if (!(sc->flags & XCHK_TRY_HARDER) && error == -EDEADLOCK) { 513 /* 514 * Scrubbers return -EDEADLOCK to mean 'try harder'. 515 * Tear down everything we hold, then set up again with 516 * preparation for worst-case scenarios. 517 */ 518 error = xchk_teardown(sc, 0); 519 if (error) 520 goto out_sc; 521 sc->flags |= XCHK_TRY_HARDER; 522 goto retry_op; 523 } else if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE)) 524 goto out_teardown; 525 526 xchk_update_health(sc); 527 528 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 529 !(sc->flags & XREP_ALREADY_FIXED)) { 530 bool needs_fix; 531 532 /* Let debug users force us into the repair routines. */ 533 if (XFS_TEST_ERROR(false, mp, XFS_ERRTAG_FORCE_SCRUB_REPAIR)) 534 sc->sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 535 536 needs_fix = (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 537 XFS_SCRUB_OFLAG_XCORRUPT | 538 XFS_SCRUB_OFLAG_PREEN)); 539 /* 540 * If userspace asked for a repair but it wasn't necessary, 541 * report that back to userspace. 542 */ 543 if (!needs_fix) { 544 sc->sm->sm_flags |= XFS_SCRUB_OFLAG_NO_REPAIR_NEEDED; 545 goto out_nofix; 546 } 547 548 /* 549 * If it's broken, userspace wants us to fix it, and we haven't 550 * already tried to fix it, then attempt a repair. 551 */ 552 error = xrep_attempt(sc); 553 if (error == -EAGAIN) { 554 /* 555 * Either the repair function succeeded or it couldn't 556 * get all the resources it needs; either way, we go 557 * back to the beginning and call the scrub function. 558 */ 559 error = xchk_teardown(sc, 0); 560 if (error) { 561 xrep_failure(mp); 562 goto out_sc; 563 } 564 goto retry_op; 565 } 566 } 567 568 out_nofix: 569 xchk_postmortem(sc); 570 out_teardown: 571 error = xchk_teardown(sc, error); 572 out_sc: 573 kmem_free(sc); 574 out: 575 trace_xchk_done(XFS_I(file_inode(file)), sm, error); 576 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 577 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 578 error = 0; 579 } 580 return error; 581 } 582