1 /* 2 * Copyright (C) 2017 Oracle. All Rights Reserved. 3 * 4 * Author: Darrick J. Wong <darrick.wong@oracle.com> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 2 9 * of the License, or (at your option) any later version. 10 * 11 * This program is distributed in the hope that it would be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. 19 */ 20 #include "xfs.h" 21 #include "xfs_fs.h" 22 #include "xfs_shared.h" 23 #include "xfs_format.h" 24 #include "xfs_trans_resv.h" 25 #include "xfs_mount.h" 26 #include "xfs_defer.h" 27 #include "xfs_btree.h" 28 #include "xfs_bit.h" 29 #include "xfs_log_format.h" 30 #include "xfs_trans.h" 31 #include "xfs_sb.h" 32 #include "xfs_inode.h" 33 #include "xfs_icache.h" 34 #include "xfs_itable.h" 35 #include "xfs_alloc.h" 36 #include "xfs_alloc_btree.h" 37 #include "xfs_bmap.h" 38 #include "xfs_bmap_btree.h" 39 #include "xfs_ialloc.h" 40 #include "xfs_ialloc_btree.h" 41 #include "xfs_refcount.h" 42 #include "xfs_refcount_btree.h" 43 #include "xfs_rmap.h" 44 #include "xfs_rmap_btree.h" 45 #include "scrub/xfs_scrub.h" 46 #include "scrub/scrub.h" 47 #include "scrub/common.h" 48 #include "scrub/trace.h" 49 #include "scrub/btree.h" 50 51 /* 52 * Online Scrub and Repair 53 * 54 * Traditionally, XFS (the kernel driver) did not know how to check or 55 * repair on-disk data structures. That task was left to the xfs_check 56 * and xfs_repair tools, both of which require taking the filesystem 57 * offline for a thorough but time consuming examination. Online 58 * scrub & repair, on the other hand, enables us to check the metadata 59 * for obvious errors while carefully stepping around the filesystem's 60 * ongoing operations, locking rules, etc. 61 * 62 * Given that most XFS metadata consist of records stored in a btree, 63 * most of the checking functions iterate the btree blocks themselves 64 * looking for irregularities. When a record block is encountered, each 65 * record can be checked for obviously bad values. Record values can 66 * also be cross-referenced against other btrees to look for potential 67 * misunderstandings between pieces of metadata. 68 * 69 * It is expected that the checkers responsible for per-AG metadata 70 * structures will lock the AG headers (AGI, AGF, AGFL), iterate the 71 * metadata structure, and perform any relevant cross-referencing before 72 * unlocking the AG and returning the results to userspace. These 73 * scrubbers must not keep an AG locked for too long to avoid tying up 74 * the block and inode allocators. 75 * 76 * Block maps and b-trees rooted in an inode present a special challenge 77 * because they can involve extents from any AG. The general scrubber 78 * structure of lock -> check -> xref -> unlock still holds, but AG 79 * locking order rules /must/ be obeyed to avoid deadlocks. The 80 * ordering rule, of course, is that we must lock in increasing AG 81 * order. Helper functions are provided to track which AG headers we've 82 * already locked. If we detect an imminent locking order violation, we 83 * can signal a potential deadlock, in which case the scrubber can jump 84 * out to the top level, lock all the AGs in order, and retry the scrub. 85 * 86 * For file data (directories, extended attributes, symlinks) scrub, we 87 * can simply lock the inode and walk the data. For btree data 88 * (directories and attributes) we follow the same btree-scrubbing 89 * strategy outlined previously to check the records. 90 * 91 * We use a bit of trickery with transactions to avoid buffer deadlocks 92 * if there is a cycle in the metadata. The basic problem is that 93 * travelling down a btree involves locking the current buffer at each 94 * tree level. If a pointer should somehow point back to a buffer that 95 * we've already examined, we will deadlock due to the second buffer 96 * locking attempt. Note however that grabbing a buffer in transaction 97 * context links the locked buffer to the transaction. If we try to 98 * re-grab the buffer in the context of the same transaction, we avoid 99 * the second lock attempt and continue. Between the verifier and the 100 * scrubber, something will notice that something is amiss and report 101 * the corruption. Therefore, each scrubber will allocate an empty 102 * transaction, attach buffers to it, and cancel the transaction at the 103 * end of the scrub run. Cancelling a non-dirty transaction simply 104 * unlocks the buffers. 105 * 106 * There are four pieces of data that scrub can communicate to 107 * userspace. The first is the error code (errno), which can be used to 108 * communicate operational errors in performing the scrub. There are 109 * also three flags that can be set in the scrub context. If the data 110 * structure itself is corrupt, the CORRUPT flag will be set. If 111 * the metadata is correct but otherwise suboptimal, the PREEN flag 112 * will be set. 113 * 114 * We perform secondary validation of filesystem metadata by 115 * cross-referencing every record with all other available metadata. 116 * For example, for block mapping extents, we verify that there are no 117 * records in the free space and inode btrees corresponding to that 118 * space extent and that there is a corresponding entry in the reverse 119 * mapping btree. Inconsistent metadata is noted by setting the 120 * XCORRUPT flag; btree query function errors are noted by setting the 121 * XFAIL flag and deleting the cursor to prevent further attempts to 122 * cross-reference with a defective btree. 123 */ 124 125 /* 126 * Scrub probe -- userspace uses this to probe if we're willing to scrub 127 * or repair a given mountpoint. This will be used by xfs_scrub to 128 * probe the kernel's abilities to scrub (and repair) the metadata. We 129 * do this by validating the ioctl inputs from userspace, preparing the 130 * filesystem for a scrub (or a repair) operation, and immediately 131 * returning to userspace. Userspace can use the returned errno and 132 * structure state to decide (in broad terms) if scrub/repair are 133 * supported by the running kernel. 134 */ 135 static int 136 xfs_scrub_probe( 137 struct xfs_scrub_context *sc) 138 { 139 int error = 0; 140 141 if (xfs_scrub_should_terminate(sc, &error)) 142 return error; 143 144 return 0; 145 } 146 147 /* Scrub setup and teardown */ 148 149 /* Free all the resources and finish the transactions. */ 150 STATIC int 151 xfs_scrub_teardown( 152 struct xfs_scrub_context *sc, 153 struct xfs_inode *ip_in, 154 int error) 155 { 156 xfs_scrub_ag_free(sc, &sc->sa); 157 if (sc->tp) { 158 xfs_trans_cancel(sc->tp); 159 sc->tp = NULL; 160 } 161 if (sc->ip) { 162 if (sc->ilock_flags) 163 xfs_iunlock(sc->ip, sc->ilock_flags); 164 if (sc->ip != ip_in && 165 !xfs_internal_inum(sc->mp, sc->ip->i_ino)) 166 iput(VFS_I(sc->ip)); 167 sc->ip = NULL; 168 } 169 if (sc->buf) { 170 kmem_free(sc->buf); 171 sc->buf = NULL; 172 } 173 return error; 174 } 175 176 /* Scrubbing dispatch. */ 177 178 static const struct xfs_scrub_meta_ops meta_scrub_ops[] = { 179 [XFS_SCRUB_TYPE_PROBE] = { /* ioctl presence test */ 180 .type = ST_NONE, 181 .setup = xfs_scrub_setup_fs, 182 .scrub = xfs_scrub_probe, 183 }, 184 [XFS_SCRUB_TYPE_SB] = { /* superblock */ 185 .type = ST_PERAG, 186 .setup = xfs_scrub_setup_fs, 187 .scrub = xfs_scrub_superblock, 188 }, 189 [XFS_SCRUB_TYPE_AGF] = { /* agf */ 190 .type = ST_PERAG, 191 .setup = xfs_scrub_setup_fs, 192 .scrub = xfs_scrub_agf, 193 }, 194 [XFS_SCRUB_TYPE_AGFL]= { /* agfl */ 195 .type = ST_PERAG, 196 .setup = xfs_scrub_setup_fs, 197 .scrub = xfs_scrub_agfl, 198 }, 199 [XFS_SCRUB_TYPE_AGI] = { /* agi */ 200 .type = ST_PERAG, 201 .setup = xfs_scrub_setup_fs, 202 .scrub = xfs_scrub_agi, 203 }, 204 [XFS_SCRUB_TYPE_BNOBT] = { /* bnobt */ 205 .type = ST_PERAG, 206 .setup = xfs_scrub_setup_ag_allocbt, 207 .scrub = xfs_scrub_bnobt, 208 }, 209 [XFS_SCRUB_TYPE_CNTBT] = { /* cntbt */ 210 .type = ST_PERAG, 211 .setup = xfs_scrub_setup_ag_allocbt, 212 .scrub = xfs_scrub_cntbt, 213 }, 214 [XFS_SCRUB_TYPE_INOBT] = { /* inobt */ 215 .type = ST_PERAG, 216 .setup = xfs_scrub_setup_ag_iallocbt, 217 .scrub = xfs_scrub_inobt, 218 }, 219 [XFS_SCRUB_TYPE_FINOBT] = { /* finobt */ 220 .type = ST_PERAG, 221 .setup = xfs_scrub_setup_ag_iallocbt, 222 .scrub = xfs_scrub_finobt, 223 .has = xfs_sb_version_hasfinobt, 224 }, 225 [XFS_SCRUB_TYPE_RMAPBT] = { /* rmapbt */ 226 .type = ST_PERAG, 227 .setup = xfs_scrub_setup_ag_rmapbt, 228 .scrub = xfs_scrub_rmapbt, 229 .has = xfs_sb_version_hasrmapbt, 230 }, 231 [XFS_SCRUB_TYPE_REFCNTBT] = { /* refcountbt */ 232 .type = ST_PERAG, 233 .setup = xfs_scrub_setup_ag_refcountbt, 234 .scrub = xfs_scrub_refcountbt, 235 .has = xfs_sb_version_hasreflink, 236 }, 237 [XFS_SCRUB_TYPE_INODE] = { /* inode record */ 238 .type = ST_INODE, 239 .setup = xfs_scrub_setup_inode, 240 .scrub = xfs_scrub_inode, 241 }, 242 [XFS_SCRUB_TYPE_BMBTD] = { /* inode data fork */ 243 .type = ST_INODE, 244 .setup = xfs_scrub_setup_inode_bmap, 245 .scrub = xfs_scrub_bmap_data, 246 }, 247 [XFS_SCRUB_TYPE_BMBTA] = { /* inode attr fork */ 248 .type = ST_INODE, 249 .setup = xfs_scrub_setup_inode_bmap, 250 .scrub = xfs_scrub_bmap_attr, 251 }, 252 [XFS_SCRUB_TYPE_BMBTC] = { /* inode CoW fork */ 253 .type = ST_INODE, 254 .setup = xfs_scrub_setup_inode_bmap, 255 .scrub = xfs_scrub_bmap_cow, 256 }, 257 [XFS_SCRUB_TYPE_DIR] = { /* directory */ 258 .type = ST_INODE, 259 .setup = xfs_scrub_setup_directory, 260 .scrub = xfs_scrub_directory, 261 }, 262 [XFS_SCRUB_TYPE_XATTR] = { /* extended attributes */ 263 .type = ST_INODE, 264 .setup = xfs_scrub_setup_xattr, 265 .scrub = xfs_scrub_xattr, 266 }, 267 [XFS_SCRUB_TYPE_SYMLINK] = { /* symbolic link */ 268 .type = ST_INODE, 269 .setup = xfs_scrub_setup_symlink, 270 .scrub = xfs_scrub_symlink, 271 }, 272 [XFS_SCRUB_TYPE_PARENT] = { /* parent pointers */ 273 .type = ST_INODE, 274 .setup = xfs_scrub_setup_parent, 275 .scrub = xfs_scrub_parent, 276 }, 277 [XFS_SCRUB_TYPE_RTBITMAP] = { /* realtime bitmap */ 278 .type = ST_FS, 279 .setup = xfs_scrub_setup_rt, 280 .scrub = xfs_scrub_rtbitmap, 281 .has = xfs_sb_version_hasrealtime, 282 }, 283 [XFS_SCRUB_TYPE_RTSUM] = { /* realtime summary */ 284 .type = ST_FS, 285 .setup = xfs_scrub_setup_rt, 286 .scrub = xfs_scrub_rtsummary, 287 .has = xfs_sb_version_hasrealtime, 288 }, 289 [XFS_SCRUB_TYPE_UQUOTA] = { /* user quota */ 290 .type = ST_FS, 291 .setup = xfs_scrub_setup_quota, 292 .scrub = xfs_scrub_quota, 293 }, 294 [XFS_SCRUB_TYPE_GQUOTA] = { /* group quota */ 295 .type = ST_FS, 296 .setup = xfs_scrub_setup_quota, 297 .scrub = xfs_scrub_quota, 298 }, 299 [XFS_SCRUB_TYPE_PQUOTA] = { /* project quota */ 300 .type = ST_FS, 301 .setup = xfs_scrub_setup_quota, 302 .scrub = xfs_scrub_quota, 303 }, 304 }; 305 306 /* This isn't a stable feature, warn once per day. */ 307 static inline void 308 xfs_scrub_experimental_warning( 309 struct xfs_mount *mp) 310 { 311 static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT( 312 "xfs_scrub_warning", 86400 * HZ, 1); 313 ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE); 314 315 if (__ratelimit(&scrub_warning)) 316 xfs_alert(mp, 317 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 318 } 319 320 static int 321 xfs_scrub_validate_inputs( 322 struct xfs_mount *mp, 323 struct xfs_scrub_metadata *sm) 324 { 325 int error; 326 const struct xfs_scrub_meta_ops *ops; 327 328 error = -EINVAL; 329 /* Check our inputs. */ 330 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 331 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 332 goto out; 333 /* sm_reserved[] must be zero */ 334 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 335 goto out; 336 337 error = -ENOENT; 338 /* Do we know about this type of metadata? */ 339 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 340 goto out; 341 ops = &meta_scrub_ops[sm->sm_type]; 342 if (ops->setup == NULL || ops->scrub == NULL) 343 goto out; 344 /* Does this fs even support this type of metadata? */ 345 if (ops->has && !ops->has(&mp->m_sb)) 346 goto out; 347 348 error = -EINVAL; 349 /* restricting fields must be appropriate for type */ 350 switch (ops->type) { 351 case ST_NONE: 352 case ST_FS: 353 if (sm->sm_ino || sm->sm_gen || sm->sm_agno) 354 goto out; 355 break; 356 case ST_PERAG: 357 if (sm->sm_ino || sm->sm_gen || 358 sm->sm_agno >= mp->m_sb.sb_agcount) 359 goto out; 360 break; 361 case ST_INODE: 362 if (sm->sm_agno || (sm->sm_gen && !sm->sm_ino)) 363 goto out; 364 break; 365 default: 366 goto out; 367 } 368 369 error = -EOPNOTSUPP; 370 /* 371 * We won't scrub any filesystem that doesn't have the ability 372 * to record unwritten extents. The option was made default in 373 * 2003, removed from mkfs in 2007, and cannot be disabled in 374 * v5, so if we find a filesystem without this flag it's either 375 * really old or totally unsupported. Avoid it either way. 376 * We also don't support v1-v3 filesystems, which aren't 377 * mountable. 378 */ 379 if (!xfs_sb_version_hasextflgbit(&mp->m_sb)) 380 goto out; 381 382 /* We don't know how to repair anything yet. */ 383 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) 384 goto out; 385 386 error = 0; 387 out: 388 return error; 389 } 390 391 /* Dispatch metadata scrubbing. */ 392 int 393 xfs_scrub_metadata( 394 struct xfs_inode *ip, 395 struct xfs_scrub_metadata *sm) 396 { 397 struct xfs_scrub_context sc; 398 struct xfs_mount *mp = ip->i_mount; 399 bool try_harder = false; 400 int error = 0; 401 402 BUILD_BUG_ON(sizeof(meta_scrub_ops) != 403 (sizeof(struct xfs_scrub_meta_ops) * XFS_SCRUB_TYPE_NR)); 404 405 trace_xfs_scrub_start(ip, sm, error); 406 407 /* Forbidden if we are shut down or mounted norecovery. */ 408 error = -ESHUTDOWN; 409 if (XFS_FORCED_SHUTDOWN(mp)) 410 goto out; 411 error = -ENOTRECOVERABLE; 412 if (mp->m_flags & XFS_MOUNT_NORECOVERY) 413 goto out; 414 415 error = xfs_scrub_validate_inputs(mp, sm); 416 if (error) 417 goto out; 418 419 xfs_scrub_experimental_warning(mp); 420 421 retry_op: 422 /* Set up for the operation. */ 423 memset(&sc, 0, sizeof(sc)); 424 sc.mp = ip->i_mount; 425 sc.sm = sm; 426 sc.ops = &meta_scrub_ops[sm->sm_type]; 427 sc.try_harder = try_harder; 428 sc.sa.agno = NULLAGNUMBER; 429 error = sc.ops->setup(&sc, ip); 430 if (error) 431 goto out_teardown; 432 433 /* Scrub for errors. */ 434 error = sc.ops->scrub(&sc); 435 if (!try_harder && error == -EDEADLOCK) { 436 /* 437 * Scrubbers return -EDEADLOCK to mean 'try harder'. 438 * Tear down everything we hold, then set up again with 439 * preparation for worst-case scenarios. 440 */ 441 error = xfs_scrub_teardown(&sc, ip, 0); 442 if (error) 443 goto out; 444 try_harder = true; 445 goto retry_op; 446 } else if (error) 447 goto out_teardown; 448 449 if (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 450 XFS_SCRUB_OFLAG_XCORRUPT)) 451 xfs_alert_ratelimited(mp, "Corruption detected during scrub."); 452 453 out_teardown: 454 error = xfs_scrub_teardown(&sc, ip, error); 455 out: 456 trace_xfs_scrub_done(ip, sm, error); 457 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 458 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 459 error = 0; 460 } 461 return error; 462 } 463