1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright (c) 2020-2024 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <djwong@kernel.org>
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_trans_resv.h"
11 #include "xfs_mount.h"
12 #include "xfs_defer.h"
14 #include "xfs_log_format.h"
15 #include "xfs_trans.h"
17 #include "xfs_inode.h"
18 #include "xfs_icache.h"
19 #include "xfs_da_format.h"
20 #include "xfs_da_btree.h"
22 #include "xfs_bmap_btree.h"
23 #include "xfs_dir2_priv.h"
24 #include "xfs_trans_space.h"
25 #include "xfs_health.h"
26 #include "xfs_exchmaps.h"
27 #include "scrub/xfs_scrub.h"
28 #include "scrub/scrub.h"
29 #include "scrub/common.h"
30 #include "scrub/trace.h"
31 #include "scrub/repair.h"
32 #include "scrub/iscan.h"
33 #include "scrub/findparent.h"
34 #include "scrub/readdir.h"
35 #include "scrub/tempfile.h"
38 * Finding the Parent of a Directory
39 * =================================
41 * Directories have parent pointers, in the sense that each directory contains
42 * a dotdot entry that points to the single allowed parent. The brute force
43 * way to find the parent of a given directory is to scan every directory in
44 * the filesystem looking for a child dirent that references this directory.
46 * This module wraps the process of scanning the directory tree. It requires
47 * that @sc->ip is the directory whose parent we want to find, and that the
48 * caller hold only the IOLOCK on that directory. The scan itself needs to
49 * take the ILOCK of each directory visited.
51 * Because we cannot hold @sc->ip's ILOCK during a scan of the whole fs, it is
52 * necessary to use dirent hook to update the parent scan results. Callers
53 * must not read the scan results without re-taking @sc->ip's ILOCK.
55 * There are a few shortcuts that we can take to avoid scanning the entire
56 * filesystem, such as noticing directory tree roots and querying the dentry
57 * cache for parent information.
60 struct xrep_findparent_info {
61 /* The directory currently being scanned. */
65 * Scrub context. We're looking for a @dp containing a directory
66 * entry pointing to sc->ip->i_ino.
70 /* Optional scan information for a xrep_findparent_scan call. */
71 struct xrep_parent_scan_info *parent_scan;
74 * Parent that we've found for sc->ip. If we're scanning the entire
75 * directory tree, we need this to ensure that we only find /one/
78 xfs_ino_t found_parent;
81 * This is set to true if @found_parent was not observed directly from
82 * the directory scan but by noticing a change in dotdot entries after
83 * cycling the sc->ip IOLOCK.
85 bool parent_tentative;
89 * If this directory entry points to the scrub target inode, then the directory
90 * we're scanning is the parent of the scrub target inode.
93 xrep_findparent_dirent(
96 xfs_dir2_dataptr_t dapos,
97 const struct xfs_name *name,
101 struct xrep_findparent_info *fpi = priv;
104 if (xchk_should_terminate(fpi->sc, &error))
107 if (ino != fpi->sc->ip->i_ino)
110 /* Ignore garbage directory entry names. */
111 if (name->len == 0 || !xfs_dir2_namecheck(name->name, name->len))
112 return -EFSCORRUPTED;
115 * Ignore dotdot and dot entries -- we're looking for parent -> child
118 if (name->name[0] == '.' && (name->len == 1 ||
119 (name->len == 2 && name->name[1] == '.')))
122 /* Uhoh, more than one parent for a dir? */
123 if (fpi->found_parent != NULLFSINO &&
124 !(fpi->parent_tentative && fpi->found_parent == fpi->dp->i_ino)) {
125 trace_xrep_findparent_dirent(fpi->sc->ip, 0);
126 return -EFSCORRUPTED;
129 /* We found a potential parent; remember this. */
130 trace_xrep_findparent_dirent(fpi->sc->ip, fpi->dp->i_ino);
131 fpi->found_parent = fpi->dp->i_ino;
132 fpi->parent_tentative = false;
134 if (fpi->parent_scan)
135 xrep_findparent_scan_found(fpi->parent_scan, fpi->dp->i_ino);
141 * If this is a directory, walk the dirents looking for any that point to the
142 * scrub target inode.
145 xrep_findparent_walk_directory(
146 struct xrep_findparent_info *fpi)
148 struct xfs_scrub *sc = fpi->sc;
149 struct xfs_inode *dp = fpi->dp;
150 unsigned int lock_mode;
154 * The inode being scanned cannot be its own parent, nor can any
155 * temporary directory we created to stage this repair.
157 if (dp == sc->ip || dp == sc->tempip)
161 * Similarly, temporary files created to stage a repair cannot be the
162 * parent of this inode.
164 if (xrep_is_tempfile(dp))
168 * Scan the directory to see if there it contains an entry pointing to
169 * the directory that we are repairing.
171 lock_mode = xfs_ilock_data_map_shared(dp);
174 * If this directory is known to be sick, we cannot scan it reliably
177 if (xfs_inode_has_sickness(dp, XFS_SICK_INO_CORE |
180 error = -EFSCORRUPTED;
185 * We cannot complete our parent pointer scan if a directory looks as
186 * though it has been zapped by the inode record repair code.
188 if (xchk_dir_looks_zapped(dp)) {
193 error = xchk_dir_walk(sc, dp, xrep_findparent_dirent, fpi);
198 xfs_iunlock(dp, lock_mode);
203 * Update this directory's dotdot pointer based on ongoing dirent updates.
206 xrep_findparent_live_update(
207 struct notifier_block *nb,
208 unsigned long action,
211 struct xfs_dir_update_params *p = data;
212 struct xrep_parent_scan_info *pscan;
213 struct xfs_scrub *sc;
215 pscan = container_of(nb, struct xrep_parent_scan_info,
216 dhook.dirent_hook.nb);
220 * If @p->ip is the subdirectory that we're interested in and we've
221 * already scanned @p->dp, update the dotdot target inumber to the
224 if (p->ip->i_ino == sc->ip->i_ino &&
225 xchk_iscan_want_live_update(&pscan->iscan, p->dp->i_ino)) {
227 xrep_findparent_scan_found(pscan, p->dp->i_ino);
229 xrep_findparent_scan_found(pscan, NULLFSINO);
237 * Set up a scan to find the parent of a directory. The provided dirent hook
238 * will be called when there is a dotdot update for the inode being repaired.
241 __xrep_findparent_scan_start(
242 struct xfs_scrub *sc,
243 struct xrep_parent_scan_info *pscan,
244 notifier_fn_t custom_fn)
248 if (!(sc->flags & XCHK_FSGATES_DIRENTS)) {
249 ASSERT(sc->flags & XCHK_FSGATES_DIRENTS);
254 pscan->parent_ino = NULLFSINO;
256 mutex_init(&pscan->lock);
258 xchk_iscan_start(sc, 30000, 100, &pscan->iscan);
261 * Hook into the dirent update code. The hook only operates on inodes
262 * that were already scanned, and the scanner thread takes each inode's
263 * ILOCK, which means that any in-progress inode updates will finish
264 * before we can scan the inode.
267 xfs_dir_hook_setup(&pscan->dhook, custom_fn);
269 xfs_dir_hook_setup(&pscan->dhook, xrep_findparent_live_update);
270 error = xfs_dir_hook_add(sc->mp, &pscan->dhook);
276 xchk_iscan_teardown(&pscan->iscan);
277 mutex_destroy(&pscan->lock);
282 * Scan the entire filesystem looking for a parent inode for the inode being
283 * scrubbed. @sc->ip must not be the root of a directory tree. Callers must
284 * not hold a dirty transaction or any lock that would interfere with taking
287 * Returns 0 with @pscan->parent_ino set to the parent that we found.
288 * Returns 0 with @pscan->parent_ino set to NULLFSINO if we found no parents.
289 * Returns the usual negative errno if something else happened.
292 xrep_findparent_scan(
293 struct xrep_parent_scan_info *pscan)
295 struct xrep_findparent_info fpi = {
297 .found_parent = NULLFSINO,
298 .parent_scan = pscan,
300 struct xfs_scrub *sc = pscan->sc;
303 ASSERT(S_ISDIR(VFS_IC(sc->ip)->i_mode));
305 while ((ret = xchk_iscan_iter(&pscan->iscan, &fpi.dp)) == 1) {
306 if (S_ISDIR(VFS_I(fpi.dp)->i_mode))
307 ret = xrep_findparent_walk_directory(&fpi);
310 xchk_iscan_mark_visited(&pscan->iscan, fpi.dp);
311 xchk_irele(sc, fpi.dp);
315 if (xchk_should_terminate(sc, &ret))
318 xchk_iscan_iter_finish(&pscan->iscan);
323 /* Tear down a parent scan. */
325 xrep_findparent_scan_teardown(
326 struct xrep_parent_scan_info *pscan)
328 xfs_dir_hook_del(pscan->sc->mp, &pscan->dhook);
329 xchk_iscan_teardown(&pscan->iscan);
330 mutex_destroy(&pscan->lock);
333 /* Finish a parent scan early. */
335 xrep_findparent_scan_finish_early(
336 struct xrep_parent_scan_info *pscan,
339 xrep_findparent_scan_found(pscan, ino);
340 xchk_iscan_finish_early(&pscan->iscan);
344 * Confirm that the directory @parent_ino actually contains a directory entry
345 * pointing to the child @sc->ip->ino. This function returns one of several
348 * Returns 0 with @parent_ino unchanged if the parent was confirmed.
349 * Returns 0 with @parent_ino set to NULLFSINO if the parent was not valid.
350 * Returns the usual negative errno if something else happened.
353 xrep_findparent_confirm(
354 struct xfs_scrub *sc,
355 xfs_ino_t *parent_ino)
357 struct xrep_findparent_info fpi = {
359 .found_parent = NULLFSINO,
364 * The root directory always points to itself. Unlinked dirs can point
365 * anywhere, so we point them at the root dir too.
367 if (sc->ip == sc->mp->m_rootip || VFS_I(sc->ip)->i_nlink == 0) {
368 *parent_ino = sc->mp->m_sb.sb_rootino;
372 /* Reject garbage parent inode numbers and self-referential parents. */
373 if (*parent_ino == NULLFSINO)
375 if (!xfs_verify_dir_ino(sc->mp, *parent_ino) ||
376 *parent_ino == sc->ip->i_ino) {
377 *parent_ino = NULLFSINO;
381 error = xchk_iget(sc, *parent_ino, &fpi.dp);
385 if (!S_ISDIR(VFS_I(fpi.dp)->i_mode)) {
386 *parent_ino = NULLFSINO;
390 error = xrep_findparent_walk_directory(&fpi);
394 *parent_ino = fpi.found_parent;
396 xchk_irele(sc, fpi.dp);
401 * If we're the root of a directory tree, we are our own parent. If we're an
402 * unlinked directory, the parent /won't/ have a link to us. Set the parent
403 * directory to the root for both cases. Returns NULLFSINO if we don't know
407 xrep_findparent_self_reference(
408 struct xfs_scrub *sc)
410 if (sc->ip->i_ino == sc->mp->m_sb.sb_rootino)
411 return sc->mp->m_sb.sb_rootino;
413 if (VFS_I(sc->ip)->i_nlink == 0)
414 return sc->mp->m_sb.sb_rootino;
419 /* Check the dentry cache to see if knows of a parent for the scrub target. */
421 xrep_findparent_from_dcache(
422 struct xfs_scrub *sc)
424 struct inode *pip = NULL;
425 struct dentry *dentry, *parent;
426 xfs_ino_t ret = NULLFSINO;
428 dentry = d_find_alias(VFS_I(sc->ip));
432 parent = dget_parent(dentry);
436 ASSERT(parent->d_sb == sc->ip->i_mount->m_super);
438 pip = igrab(d_inode(parent));
441 if (S_ISDIR(pip->i_mode)) {
442 trace_xrep_findparent_from_dcache(sc->ip, XFS_I(pip)->i_ino);
443 ret = XFS_I(pip)->i_ino;
446 xchk_irele(sc, XFS_I(pip));