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 */ 114 115 /* 116 * Scrub probe -- userspace uses this to probe if we're willing to scrub 117 * or repair a given mountpoint. This will be used by xfs_scrub to 118 * probe the kernel's abilities to scrub (and repair) the metadata. We 119 * do this by validating the ioctl inputs from userspace, preparing the 120 * filesystem for a scrub (or a repair) operation, and immediately 121 * returning to userspace. Userspace can use the returned errno and 122 * structure state to decide (in broad terms) if scrub/repair are 123 * supported by the running kernel. 124 */ 125 static int 126 xfs_scrub_probe( 127 struct xfs_scrub_context *sc) 128 { 129 int error = 0; 130 131 if (sc->sm->sm_ino || sc->sm->sm_agno) 132 return -EINVAL; 133 if (xfs_scrub_should_terminate(sc, &error)) 134 return error; 135 136 return 0; 137 } 138 139 /* Scrub setup and teardown */ 140 141 /* Free all the resources and finish the transactions. */ 142 STATIC int 143 xfs_scrub_teardown( 144 struct xfs_scrub_context *sc, 145 struct xfs_inode *ip_in, 146 int error) 147 { 148 xfs_scrub_ag_free(sc, &sc->sa); 149 if (sc->tp) { 150 xfs_trans_cancel(sc->tp); 151 sc->tp = NULL; 152 } 153 if (sc->ip) { 154 xfs_iunlock(sc->ip, sc->ilock_flags); 155 if (sc->ip != ip_in && 156 !xfs_internal_inum(sc->mp, sc->ip->i_ino)) 157 iput(VFS_I(sc->ip)); 158 sc->ip = NULL; 159 } 160 if (sc->buf) { 161 kmem_free(sc->buf); 162 sc->buf = NULL; 163 } 164 return error; 165 } 166 167 /* Scrubbing dispatch. */ 168 169 static const struct xfs_scrub_meta_ops meta_scrub_ops[] = { 170 { /* ioctl presence test */ 171 .setup = xfs_scrub_setup_fs, 172 .scrub = xfs_scrub_probe, 173 }, 174 { /* superblock */ 175 .setup = xfs_scrub_setup_ag_header, 176 .scrub = xfs_scrub_superblock, 177 }, 178 { /* agf */ 179 .setup = xfs_scrub_setup_ag_header, 180 .scrub = xfs_scrub_agf, 181 }, 182 { /* agfl */ 183 .setup = xfs_scrub_setup_ag_header, 184 .scrub = xfs_scrub_agfl, 185 }, 186 { /* agi */ 187 .setup = xfs_scrub_setup_ag_header, 188 .scrub = xfs_scrub_agi, 189 }, 190 { /* bnobt */ 191 .setup = xfs_scrub_setup_ag_allocbt, 192 .scrub = xfs_scrub_bnobt, 193 }, 194 { /* cntbt */ 195 .setup = xfs_scrub_setup_ag_allocbt, 196 .scrub = xfs_scrub_cntbt, 197 }, 198 { /* inobt */ 199 .setup = xfs_scrub_setup_ag_iallocbt, 200 .scrub = xfs_scrub_inobt, 201 }, 202 { /* finobt */ 203 .setup = xfs_scrub_setup_ag_iallocbt, 204 .scrub = xfs_scrub_finobt, 205 .has = xfs_sb_version_hasfinobt, 206 }, 207 { /* rmapbt */ 208 .setup = xfs_scrub_setup_ag_rmapbt, 209 .scrub = xfs_scrub_rmapbt, 210 .has = xfs_sb_version_hasrmapbt, 211 }, 212 { /* refcountbt */ 213 .setup = xfs_scrub_setup_ag_refcountbt, 214 .scrub = xfs_scrub_refcountbt, 215 .has = xfs_sb_version_hasreflink, 216 }, 217 { /* inode record */ 218 .setup = xfs_scrub_setup_inode, 219 .scrub = xfs_scrub_inode, 220 }, 221 { /* inode data fork */ 222 .setup = xfs_scrub_setup_inode_bmap, 223 .scrub = xfs_scrub_bmap_data, 224 }, 225 { /* inode attr fork */ 226 .setup = xfs_scrub_setup_inode_bmap, 227 .scrub = xfs_scrub_bmap_attr, 228 }, 229 { /* inode CoW fork */ 230 .setup = xfs_scrub_setup_inode_bmap, 231 .scrub = xfs_scrub_bmap_cow, 232 }, 233 { /* directory */ 234 .setup = xfs_scrub_setup_directory, 235 .scrub = xfs_scrub_directory, 236 }, 237 { /* extended attributes */ 238 .setup = xfs_scrub_setup_xattr, 239 .scrub = xfs_scrub_xattr, 240 }, 241 { /* symbolic link */ 242 .setup = xfs_scrub_setup_symlink, 243 .scrub = xfs_scrub_symlink, 244 }, 245 { /* parent pointers */ 246 .setup = xfs_scrub_setup_parent, 247 .scrub = xfs_scrub_parent, 248 }, 249 { /* realtime bitmap */ 250 .setup = xfs_scrub_setup_rt, 251 .scrub = xfs_scrub_rtbitmap, 252 .has = xfs_sb_version_hasrealtime, 253 }, 254 { /* realtime summary */ 255 .setup = xfs_scrub_setup_rt, 256 .scrub = xfs_scrub_rtsummary, 257 .has = xfs_sb_version_hasrealtime, 258 }, 259 { /* user quota */ 260 .setup = xfs_scrub_setup_quota, 261 .scrub = xfs_scrub_quota, 262 }, 263 { /* group quota */ 264 .setup = xfs_scrub_setup_quota, 265 .scrub = xfs_scrub_quota, 266 }, 267 { /* project quota */ 268 .setup = xfs_scrub_setup_quota, 269 .scrub = xfs_scrub_quota, 270 }, 271 }; 272 273 /* This isn't a stable feature, warn once per day. */ 274 static inline void 275 xfs_scrub_experimental_warning( 276 struct xfs_mount *mp) 277 { 278 static struct ratelimit_state scrub_warning = RATELIMIT_STATE_INIT( 279 "xfs_scrub_warning", 86400 * HZ, 1); 280 ratelimit_set_flags(&scrub_warning, RATELIMIT_MSG_ON_RELEASE); 281 282 if (__ratelimit(&scrub_warning)) 283 xfs_alert(mp, 284 "EXPERIMENTAL online scrub feature in use. Use at your own risk!"); 285 } 286 287 /* Dispatch metadata scrubbing. */ 288 int 289 xfs_scrub_metadata( 290 struct xfs_inode *ip, 291 struct xfs_scrub_metadata *sm) 292 { 293 struct xfs_scrub_context sc; 294 struct xfs_mount *mp = ip->i_mount; 295 const struct xfs_scrub_meta_ops *ops; 296 bool try_harder = false; 297 int error = 0; 298 299 trace_xfs_scrub_start(ip, sm, error); 300 301 /* Forbidden if we are shut down or mounted norecovery. */ 302 error = -ESHUTDOWN; 303 if (XFS_FORCED_SHUTDOWN(mp)) 304 goto out; 305 error = -ENOTRECOVERABLE; 306 if (mp->m_flags & XFS_MOUNT_NORECOVERY) 307 goto out; 308 309 /* Check our inputs. */ 310 error = -EINVAL; 311 sm->sm_flags &= ~XFS_SCRUB_FLAGS_OUT; 312 if (sm->sm_flags & ~XFS_SCRUB_FLAGS_IN) 313 goto out; 314 if (memchr_inv(sm->sm_reserved, 0, sizeof(sm->sm_reserved))) 315 goto out; 316 317 /* Do we know about this type of metadata? */ 318 error = -ENOENT; 319 if (sm->sm_type >= XFS_SCRUB_TYPE_NR) 320 goto out; 321 ops = &meta_scrub_ops[sm->sm_type]; 322 if (ops->scrub == NULL) 323 goto out; 324 325 /* 326 * We won't scrub any filesystem that doesn't have the ability 327 * to record unwritten extents. The option was made default in 328 * 2003, removed from mkfs in 2007, and cannot be disabled in 329 * v5, so if we find a filesystem without this flag it's either 330 * really old or totally unsupported. Avoid it either way. 331 * We also don't support v1-v3 filesystems, which aren't 332 * mountable. 333 */ 334 error = -EOPNOTSUPP; 335 if (!xfs_sb_version_hasextflgbit(&mp->m_sb)) 336 goto out; 337 338 /* Does this fs even support this type of metadata? */ 339 error = -ENOENT; 340 if (ops->has && !ops->has(&mp->m_sb)) 341 goto out; 342 343 /* We don't know how to repair anything yet. */ 344 error = -EOPNOTSUPP; 345 if (sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR) 346 goto out; 347 348 xfs_scrub_experimental_warning(mp); 349 350 retry_op: 351 /* Set up for the operation. */ 352 memset(&sc, 0, sizeof(sc)); 353 sc.mp = ip->i_mount; 354 sc.sm = sm; 355 sc.ops = ops; 356 sc.try_harder = try_harder; 357 sc.sa.agno = NULLAGNUMBER; 358 error = sc.ops->setup(&sc, ip); 359 if (error) 360 goto out_teardown; 361 362 /* Scrub for errors. */ 363 error = sc.ops->scrub(&sc); 364 if (!try_harder && error == -EDEADLOCK) { 365 /* 366 * Scrubbers return -EDEADLOCK to mean 'try harder'. 367 * Tear down everything we hold, then set up again with 368 * preparation for worst-case scenarios. 369 */ 370 error = xfs_scrub_teardown(&sc, ip, 0); 371 if (error) 372 goto out; 373 try_harder = true; 374 goto retry_op; 375 } else if (error) 376 goto out_teardown; 377 378 if (sc.sm->sm_flags & (XFS_SCRUB_OFLAG_CORRUPT | 379 XFS_SCRUB_OFLAG_XCORRUPT)) 380 xfs_alert_ratelimited(mp, "Corruption detected during scrub."); 381 382 out_teardown: 383 error = xfs_scrub_teardown(&sc, ip, error); 384 out: 385 trace_xfs_scrub_done(ip, sm, error); 386 if (error == -EFSCORRUPTED || error == -EFSBADCRC) { 387 sm->sm_flags |= XFS_SCRUB_OFLAG_CORRUPT; 388 error = 0; 389 } 390 return error; 391 } 392