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 static int 344 xchk_validate_inputs( 345 struct xfs_mount *mp, 346 struct xfs_scrub_metadata *sm) 347 { 348 int error; 349 const struct xchk_meta_ops *ops; 350 351 error = -EINVAL; 352 /* Check our inputs. */ 353 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 354 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 355 goto out; 356 /* sm_reserved[] must be zero */ 357 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 358 goto out; 359 360 error = -ENOENT; 361 /* Do we know about this type of metadata? */ 362 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 363 goto out; 364 ops = &meta_scrub_ops[sm->sm_type]; 365 if (ops->setup == NULL || ops->scrub == NULL) 366 goto out; 367 /* Does this fs even support this type of metadata? */ 368 if (ops->has && !ops->has(mp)) 369 goto out; 370 371 error = -EINVAL; 372 /* restricting fields must be appropriate for type */ 373 switch (ops->type) { 374 case ST_NONE: 375 case ST_FS: 376 if (sm->sm_ino || sm->sm_gen || sm->sm_agno) 377 goto out; 378 break; 379 case ST_PERAG: 380 if (sm->sm_ino || sm->sm_gen || 381 sm->sm_agno >= mp->m_sb.sb_agcount) 382 goto out; 383 break; 384 case ST_INODE: 385 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) 386 goto out; 387 break; 388 default: 389 goto out; 390 } 391 392 /* 393 * We only want to repair read-write v5+ filesystems. Defer the check 394 * for ops->repair until after our scrub confirms that we need to 395 * perform repairs so that we avoid failing due to not supporting 396 * repairing an object that doesn't need repairs. 397 */ 398 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 399 error = -EOPNOTSUPP; 400 if (!xfs_has_crc(mp)) 401 goto out; 402 403 error = -EROFS; 404 if (xfs_is_readonly(mp)) 405 goto out; 406 } 407 408 error = 0; 409 out: 410 return error; 411 } 412 413 #ifdef CONFIG_XFS_ONLINE_REPAIR 414 static inline void xchk_postmortem(struct xfs_scrub *sc) 415 { 416 /* 417 * Userspace asked us to repair something, we repaired it, rescanned 418 * it, and the rescan says it's still broken. Scream about this in 419 * the system logs. 420 */ 421 if ((sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) && 422 (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 423 XFS_SCRUB_OFLAG_XCORRUPT))) 424 xrep_failure(sc->mp); 425 } 426 #else 427 static inline void xchk_postmortem(struct xfs_scrub *sc) 428 { 429 /* 430 * Userspace asked us to scrub something, it's broken, and we have no 431 * way of fixing it. Scream in the logs. 432 */ 433 if (sc->sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 434 XFS_SCRUB_OFLAG_XCORRUPT)) 435 xfs_alert_ratelimited(sc->mp, 436 "Corruption detected during scrub."); 437 } 438 #endif /* CONFIG_XFS_ONLINE_REPAIR */ 439 440 /* Dispatch metadata scrubbing. */ 441 int 442 xfs_scrub_metadata( 443 struct file *file, 444 struct xfs_scrub_metadata *sm) 445 { 446 struct xfs_scrub *sc; 447 struct xfs_mount *mp = XFS_I(file_inode(file))->i_mount; 448 int error = 0; 449 450 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 451 (sizeof(struct xchk_meta_ops) * XFS_SCRUB_TYPE_NR)); 452 453 trace_xchk_start(XFS_I(file_inode(file)), sm, error); 454 455 /* Forbidden if we are shut down or mounted norecovery. */ 456 error = -ESHUTDOWN; 457 if (xfs_is_shutdown(mp)) 458 goto out; 459 error = -ENOTRECOVERABLE; 460 if (xfs_has_norecovery(mp)) 461 goto out; 462 463 error = xchk_validate_inputs(mp, sm); 464 if (error) 465 goto out; 466 467 xfs_warn_mount(mp, XFS_OPSTATE_WARNED_SCRUB, 468 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 469 470 sc = kmem_zalloc(sizeof(struct xfs_scrub), KM_NOFS | KM_MAYFAIL); 471 if (!sc) { 472 error = -ENOMEM; 473 goto out; 474 } 475 476 sc->mp = mp; 477 sc->file = file; 478 sc->sm = sm; 479 sc->ops = &meta_scrub_ops[sm->sm_type]; 480 sc->sick_mask = xchk_health_mask_for_scrub_type(sm->sm_type); 481 retry_op: 482 /* 483 * When repairs are allowed, prevent freezing or readonly remount while 484 * scrub is running with a real transaction. 485 */ 486 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) { 487 error = mnt_want_write_file(sc->file); 488 if (error) 489 goto out_sc; 490 } 491 492 /* Set up for the operation. */ 493 error = sc->ops->setup(sc); 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, 0); 506 if (error) 507 goto out_sc; 508 sc->flags |= XCHK_TRY_HARDER; 509 goto retry_op; 510 } else if (error || (sm->sm_flags & XFS_SCRUB_OFLAG_INCOMPLETE)) 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(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, 0); 547 if (error) { 548 xrep_failure(mp); 549 goto out_sc; 550 } 551 goto retry_op; 552 } 553 } 554 555 out_nofix: 556 xchk_postmortem(sc); 557 out_teardown: 558 error = xchk_teardown(sc, error); 559 out_sc: 560 kmem_free(sc); 561 out: 562 trace_xchk_done(XFS_I(file_inode(file)), sm, error); 563 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 564 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 565 error = 0; 566 } 567 return error; 568 } 569