1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Copyright (c) 2021-2024 Oracle. All Rights Reserved. 4 * Author: Darrick J. Wong <djwong@kernel.org> 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_icache.h" 16 #include "xfs_bmap_util.h" 17 #include "xfs_iwalk.h" 18 #include "xfs_ialloc.h" 19 #include "xfs_sb.h" 20 #include "xfs_ag.h" 21 #include "xfs_dir2.h" 22 #include "xfs_parent.h" 23 #include "scrub/scrub.h" 24 #include "scrub/common.h" 25 #include "scrub/repair.h" 26 #include "scrub/xfile.h" 27 #include "scrub/xfarray.h" 28 #include "scrub/iscan.h" 29 #include "scrub/orphanage.h" 30 #include "scrub/nlinks.h" 31 #include "scrub/trace.h" 32 #include "scrub/tempfile.h" 33 34 /* 35 * Live Inode Link Count Repair 36 * ============================ 37 * 38 * Use the live inode link count information that we collected to replace the 39 * nlink values of the incore inodes. A scrub->repair cycle should have left 40 * the live data and hooks active, so this is safe so long as we make sure the 41 * inode is locked. 42 */ 43 44 /* Set up to repair inode link counts. */ 45 int 46 xrep_setup_nlinks( 47 struct xfs_scrub *sc) 48 { 49 return xrep_orphanage_try_create(sc); 50 } 51 52 /* 53 * Inodes that aren't the root directory or the orphanage, have a nonzero link 54 * count, and no observed parents should be moved to the orphanage. 55 */ 56 static inline bool 57 xrep_nlinks_is_orphaned( 58 struct xfs_scrub *sc, 59 struct xfs_inode *ip, 60 unsigned int actual_nlink, 61 const struct xchk_nlink *obs) 62 { 63 if (obs->parents != 0) 64 return false; 65 if (xchk_inode_is_dirtree_root(ip) || ip == sc->orphanage) 66 return false; 67 return actual_nlink != 0; 68 } 69 70 /* Remove an inode from the unlinked list. */ 71 STATIC int 72 xrep_nlinks_iunlink_remove( 73 struct xfs_scrub *sc) 74 { 75 struct xfs_perag *pag; 76 int error; 77 78 pag = xfs_perag_get(sc->mp, XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino)); 79 error = xfs_iunlink_remove(sc->tp, pag, sc->ip); 80 xfs_perag_put(pag); 81 return error; 82 } 83 84 /* 85 * Correct the link count of the given inode. Because we have to grab locks 86 * and resources in a certain order, it's possible that this will be a no-op. 87 */ 88 STATIC int 89 xrep_nlinks_repair_inode( 90 struct xchk_nlink_ctrs *xnc) 91 { 92 struct xchk_nlink obs; 93 struct xfs_scrub *sc = xnc->sc; 94 struct xfs_mount *mp = sc->mp; 95 struct xfs_inode *ip = sc->ip; 96 uint64_t total_links; 97 uint64_t actual_nlink; 98 bool orphanage_available = false; 99 bool dirty = false; 100 int error; 101 102 /* 103 * Ignore temporary files being used to stage repairs, since we assume 104 * they're correct for non-directories, and the directory repair code 105 * doesn't bump the link counts for the children. 106 */ 107 if (xrep_is_tempfile(ip)) 108 return 0; 109 110 /* 111 * If the filesystem has an orphanage attached to the scrub context, 112 * prepare for a link count repair that could involve @ip being adopted 113 * by the lost+found. 114 */ 115 if (xrep_orphanage_can_adopt(sc)) { 116 error = xrep_orphanage_iolock_two(sc); 117 if (error) 118 return error; 119 120 error = xrep_adoption_trans_alloc(sc, &xnc->adoption); 121 if (error) { 122 xchk_iunlock(sc, XFS_IOLOCK_EXCL); 123 xrep_orphanage_iunlock(sc, XFS_IOLOCK_EXCL); 124 } else { 125 orphanage_available = true; 126 } 127 } 128 129 /* 130 * Either there is no orphanage or we couldn't allocate resources for 131 * that kind of update. Let's try again with only the resources we 132 * need for a simple link count update, since that's much more common. 133 */ 134 if (!orphanage_available) { 135 xchk_ilock(sc, XFS_IOLOCK_EXCL); 136 137 error = xfs_trans_alloc(mp, &M_RES(mp)->tr_link, 0, 0, 0, 138 &sc->tp); 139 if (error) { 140 xchk_iunlock(sc, XFS_IOLOCK_EXCL); 141 return error; 142 } 143 144 xchk_ilock(sc, XFS_ILOCK_EXCL); 145 xfs_trans_ijoin(sc->tp, ip, 0); 146 } 147 148 mutex_lock(&xnc->lock); 149 150 if (xchk_iscan_aborted(&xnc->collect_iscan)) { 151 error = -ECANCELED; 152 goto out_scanlock; 153 } 154 155 error = xfarray_load_sparse(xnc->nlinks, ip->i_ino, &obs); 156 if (error) 157 goto out_scanlock; 158 159 /* 160 * We're done accessing the shared scan data, so we can drop the lock. 161 * We still hold @ip's ILOCK, so its link count cannot change. 162 */ 163 mutex_unlock(&xnc->lock); 164 165 total_links = xchk_nlink_total(ip, &obs); 166 actual_nlink = VFS_I(ip)->i_nlink; 167 168 /* 169 * Non-directories cannot have directories pointing up to them. 170 * 171 * We previously set error to zero, but set it again because one static 172 * checker author fears that programmers will fail to maintain this 173 * invariant and built their tool to flag this as a security risk. A 174 * different tool author made their bot complain about the redundant 175 * store. This is a never-ending and stupid battle; both tools missed 176 * *actual bugs* elsewhere; and I no longer care. 177 */ 178 if (!S_ISDIR(VFS_I(ip)->i_mode) && obs.children != 0) { 179 trace_xrep_nlinks_unfixable_inode(mp, ip, &obs); 180 error = 0; 181 goto out_trans; 182 } 183 184 /* 185 * Decide if we're going to move this file to the orphanage, and fix 186 * up the incore link counts if we are. 187 */ 188 if (orphanage_available && 189 xrep_nlinks_is_orphaned(sc, ip, actual_nlink, &obs)) { 190 /* Figure out what name we're going to use here. */ 191 error = xrep_adoption_compute_name(&xnc->adoption, &xnc->xname); 192 if (error) 193 goto out_trans; 194 195 /* 196 * Reattach this file to the directory tree by moving it to 197 * the orphanage per the adoption parameters that we already 198 * computed. 199 */ 200 error = xrep_adoption_move(&xnc->adoption); 201 if (error) 202 goto out_trans; 203 204 /* 205 * Re-read the link counts since the reparenting will have 206 * updated our scan info. 207 */ 208 mutex_lock(&xnc->lock); 209 error = xfarray_load_sparse(xnc->nlinks, ip->i_ino, &obs); 210 mutex_unlock(&xnc->lock); 211 if (error) 212 goto out_trans; 213 214 total_links = xchk_nlink_total(ip, &obs); 215 actual_nlink = VFS_I(ip)->i_nlink; 216 dirty = true; 217 } 218 219 /* 220 * If this inode is linked from the directory tree and on the unlinked 221 * list, remove it from the unlinked list. 222 */ 223 if (total_links > 0 && xfs_inode_on_unlinked_list(ip)) { 224 error = xrep_nlinks_iunlink_remove(sc); 225 if (error) 226 goto out_trans; 227 dirty = true; 228 } 229 230 /* 231 * If this inode is not linked from the directory tree yet not on the 232 * unlinked list, put it on the unlinked list. 233 */ 234 if (total_links == 0 && !xfs_inode_on_unlinked_list(ip)) { 235 error = xfs_iunlink(sc->tp, ip); 236 if (error) 237 goto out_trans; 238 dirty = true; 239 } 240 241 /* Commit the new link count if it changed. */ 242 if (total_links != actual_nlink) { 243 trace_xrep_nlinks_update_inode(mp, ip, &obs); 244 245 set_nlink(VFS_I(ip), min_t(unsigned long long, total_links, 246 XFS_NLINK_PINNED)); 247 dirty = true; 248 } 249 250 if (!dirty) { 251 error = 0; 252 goto out_trans; 253 } 254 255 xfs_trans_log_inode(sc->tp, ip, XFS_ILOG_CORE); 256 257 error = xrep_trans_commit(sc); 258 goto out_unlock; 259 260 out_scanlock: 261 mutex_unlock(&xnc->lock); 262 out_trans: 263 xchk_trans_cancel(sc); 264 out_unlock: 265 xchk_iunlock(sc, XFS_ILOCK_EXCL); 266 if (orphanage_available) { 267 xrep_orphanage_iunlock(sc, XFS_ILOCK_EXCL); 268 xrep_orphanage_iunlock(sc, XFS_IOLOCK_EXCL); 269 } 270 xchk_iunlock(sc, XFS_IOLOCK_EXCL); 271 return error; 272 } 273 274 /* 275 * Try to visit every inode in the filesystem for repairs. Move on if we can't 276 * grab an inode, since we're still making forward progress. 277 */ 278 static int 279 xrep_nlinks_iter( 280 struct xchk_nlink_ctrs *xnc, 281 struct xfs_inode **ipp) 282 { 283 int error; 284 285 do { 286 error = xchk_iscan_iter(&xnc->compare_iscan, ipp); 287 } while (error == -EBUSY); 288 289 return error; 290 } 291 292 /* Commit the new inode link counters. */ 293 int 294 xrep_nlinks( 295 struct xfs_scrub *sc) 296 { 297 struct xchk_nlink_ctrs *xnc = sc->buf; 298 int error; 299 300 /* 301 * We need ftype for an accurate count of the number of child 302 * subdirectory links. Child subdirectories with a back link (dotdot 303 * entry) but no forward link are moved to the orphanage, so we cannot 304 * repair the link count of the parent directory based on the back link 305 * count alone. Filesystems without ftype support are rare (old V4) so 306 * we just skip out here. 307 */ 308 if (!xfs_has_ftype(sc->mp)) 309 return -EOPNOTSUPP; 310 311 /* 312 * Use the inobt to walk all allocated inodes to compare and fix the 313 * link counts. Retry iget every tenth of a second for up to 30 314 * seconds -- even if repair misses a few inodes, we still try to fix 315 * as many of them as we can. 316 */ 317 xchk_iscan_start(sc, 30000, 100, &xnc->compare_iscan); 318 ASSERT(sc->ip == NULL); 319 320 while ((error = xrep_nlinks_iter(xnc, &sc->ip)) == 1) { 321 /* 322 * Commit the scrub transaction so that we can create repair 323 * transactions with the correct reservations. 324 */ 325 xchk_trans_cancel(sc); 326 327 error = xrep_nlinks_repair_inode(xnc); 328 xchk_iscan_mark_visited(&xnc->compare_iscan, sc->ip); 329 xchk_irele(sc, sc->ip); 330 sc->ip = NULL; 331 if (error) 332 break; 333 334 if (xchk_should_terminate(sc, &error)) 335 break; 336 337 /* 338 * Create a new empty transaction so that we can advance the 339 * iscan cursor without deadlocking if the inobt has a cycle. 340 * We can only push the inactivation workqueues with an empty 341 * transaction. 342 */ 343 error = xchk_trans_alloc_empty(sc); 344 if (error) 345 break; 346 } 347 xchk_iscan_iter_finish(&xnc->compare_iscan); 348 xchk_iscan_teardown(&xnc->compare_iscan); 349 350 return error; 351 } 352