Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0-or-later
2 : /*
3 : * Copyright (C) 2021-2023 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 2007 : xrep_setup_nlinks(
47 : struct xfs_scrub *sc)
48 : {
49 2007 : 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 91360506 : struct xfs_mount *mp = ip->i_mount;
64 :
65 91360506 : if (obs->parents != 0)
66 : return false;
67 32 : if (ip == mp->m_rootip || ip == sc->orphanage)
68 : return false;
69 32 : return actual_nlink != 0;
70 : }
71 :
72 : /*
73 : * Reattach this file to the directory tree by moving it to /lost+found per the
74 : * adoption parameters that we already computed. Returns 0 for success,
75 : * -EMLINK if we cannot complete the adoption because doing so would cause a
76 : * link count overflow, or the usual negative errno.
77 : */
78 : STATIC int
79 0 : xrep_nlinks_adopt(
80 : struct xchk_nlink_ctrs *xnc)
81 : {
82 0 : int error;
83 :
84 : /* Figure out what name we're going to use here. */
85 0 : error = xrep_adoption_compute_name(&xnc->adoption, xnc->namebuf);
86 0 : if (error)
87 : return error;
88 :
89 : /*
90 : * Create the new name in the orphanage, and bump the link
91 : * count of the orphanage if we just added a directory. Then
92 : * we can set the correct nlink.
93 : */
94 0 : return xrep_adoption_commit(&xnc->adoption);
95 : }
96 :
97 : /* Remove an inode from the unlinked list. */
98 : STATIC int
99 0 : xrep_nlinks_iunlink_remove(
100 : struct xfs_scrub *sc)
101 : {
102 0 : struct xfs_perag *pag;
103 0 : int error;
104 :
105 0 : pag = xfs_perag_get(sc->mp, XFS_INO_TO_AGNO(sc->mp, sc->ip->i_ino));
106 0 : error = xfs_iunlink_remove(sc->tp, pag, sc->ip);
107 0 : xfs_perag_put(pag);
108 0 : return error;
109 : }
110 :
111 : /*
112 : * Correct the link count of the given inode. Because we have to grab locks
113 : * and resources in a certain order, it's possible that this will be a no-op.
114 : */
115 : STATIC int
116 91362510 : xrep_nlinks_repair_inode(
117 : struct xchk_nlink_ctrs *xnc)
118 : {
119 91362510 : struct xchk_nlink obs;
120 91362510 : struct xfs_scrub *sc = xnc->sc;
121 91362510 : struct xfs_mount *mp = sc->mp;
122 91362510 : struct xfs_inode *ip = sc->ip;
123 91362510 : uint64_t total_links;
124 91362510 : uint64_t actual_nlink;
125 91362510 : bool orphanage_available = false;
126 91362510 : bool adoption_performed = false;
127 91362510 : bool dirty = false;
128 91362510 : int error;
129 :
130 : /*
131 : * Ignore temporary files being used to stage repairs, since we assume
132 : * they're correct for non-directories, and the directory repair code
133 : * doesn't bump the link counts for the children.
134 : */
135 91362510 : if (xrep_is_tempfile(ip))
136 : return 0;
137 :
138 91362510 : if (sc->orphanage && sc->ip != sc->orphanage) {
139 : /*
140 : * Allocate a transaction for the adoption. We'll reserve
141 : * space for the transaction in the adoption preparation step.
142 : */
143 91360506 : error = xrep_adoption_init(sc, &xnc->adoption);
144 91360506 : if (!error) {
145 91360506 : orphanage_available = true;
146 :
147 : /* Take IOLOCK of the orphanage and the child. */
148 91360506 : error = xrep_orphanage_iolock_two(sc);
149 91360506 : if (error)
150 : return error;
151 : }
152 : }
153 : if (!orphanage_available)
154 2004 : xchk_ilock(sc, XFS_IOLOCK_EXCL);
155 :
156 91362510 : error = xfs_trans_alloc(mp, &M_RES(mp)->tr_link, 0, 0, 0, &sc->tp);
157 91362510 : if (error)
158 0 : goto out_iolock;
159 :
160 91362510 : if (orphanage_available) {
161 91360506 : error = xrep_adoption_prep(&xnc->adoption);
162 91360506 : if (error) {
163 0 : xchk_trans_cancel(sc);
164 0 : goto out_iolock;
165 : }
166 : } else {
167 2004 : xchk_ilock(sc, XFS_ILOCK_EXCL);
168 2004 : xfs_trans_ijoin(sc->tp, ip, 0);
169 : }
170 :
171 91362510 : mutex_lock(&xnc->lock);
172 :
173 91362510 : if (xchk_iscan_aborted(&xnc->collect_iscan)) {
174 0 : error = -ECANCELED;
175 0 : goto out_scanlock;
176 : }
177 :
178 91362510 : error = xfarray_load_sparse(xnc->nlinks, ip->i_ino, &obs);
179 91362510 : if (error)
180 0 : goto out_scanlock;
181 :
182 : /*
183 : * We're done accessing the shared scan data, so we can drop the lock.
184 : * We still hold @ip's ILOCK, so its link count cannot change.
185 : */
186 91362510 : mutex_unlock(&xnc->lock);
187 :
188 91362510 : total_links = xchk_nlink_total(ip, &obs);
189 91362510 : actual_nlink = VFS_I(ip)->i_nlink;
190 :
191 : /*
192 : * Non-directories cannot have directories pointing up to them.
193 : *
194 : * We previously set error to zero, but set it again because one static
195 : * checker author fears that programmers will fail to maintain this
196 : * invariant and built their tool to flag this as a security risk. A
197 : * different tool author made their bot complain about the redundant
198 : * store. This is a never-ending and stupid battle; both tools missed
199 : * *actual bugs* elsewhere; and I no longer care.
200 : */
201 91362510 : if (!S_ISDIR(VFS_I(ip)->i_mode) && obs.children != 0) {
202 0 : trace_xrep_nlinks_unfixable_inode(mp, ip, &obs);
203 0 : error = 0;
204 0 : goto out_trans;
205 : }
206 :
207 : /*
208 : * Decide if we're going to move this file to the orphanage, and fix
209 : * up the incore link counts if we are.
210 : */
211 91362542 : if (orphanage_available &&
212 : xrep_nlinks_is_orphaned(sc, ip, actual_nlink, &obs)) {
213 0 : error = xrep_nlinks_adopt(xnc);
214 0 : if (error)
215 0 : goto out_trans;
216 0 : adoption_performed = true;
217 :
218 : /* Re-read the link counts. */
219 0 : mutex_lock(&xnc->lock);
220 0 : error = xfarray_load_sparse(xnc->nlinks, ip->i_ino, &obs);
221 0 : mutex_unlock(&xnc->lock);
222 0 : if (error)
223 0 : goto out_trans;
224 :
225 0 : total_links = xchk_nlink_total(ip, &obs);
226 0 : actual_nlink = VFS_I(ip)->i_nlink;
227 0 : dirty = true;
228 : }
229 :
230 : /*
231 : * If this inode is linked from the directory tree and on the unlinked
232 : * list, remove it from the unlinked list.
233 : */
234 91362510 : if (total_links > 0 && xfs_inode_on_unlinked_list(ip)) {
235 0 : error = xrep_nlinks_iunlink_remove(sc);
236 0 : if (error)
237 0 : goto out_trans;
238 : dirty = true;
239 : }
240 :
241 : /*
242 : * If this inode is not linked from the directory tree yet not on the
243 : * unlinked list, put it on the unlinked list.
244 : */
245 91362510 : if (total_links == 0 && !xfs_inode_on_unlinked_list(ip)) {
246 0 : error = xfs_iunlink(sc->tp, ip);
247 0 : if (error)
248 0 : goto out_trans;
249 : dirty = true;
250 : }
251 :
252 : /* Commit the new link count if it changed. */
253 91362510 : if (total_links != actual_nlink) {
254 0 : bool overflow = xrep_set_nlink(ip, total_links);
255 :
256 0 : if (overflow)
257 0 : trace_xrep_nlinks_unfixable_inode(mp, ip, &obs);
258 : else
259 0 : trace_xrep_nlinks_update_inode(mp, ip, &obs);
260 : dirty = true;
261 : }
262 :
263 91362510 : if (!dirty) {
264 91362510 : error = 0;
265 91362510 : goto out_trans;
266 : }
267 :
268 0 : xfs_trans_log_inode(sc->tp, ip, XFS_ILOG_CORE);
269 :
270 0 : error = xrep_trans_commit(sc);
271 0 : if (error)
272 0 : goto out_ilock;
273 :
274 0 : xchk_iunlock(sc, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
275 0 : if (orphanage_available) {
276 0 : xrep_orphanage_iunlock(sc, XFS_ILOCK_EXCL | XFS_IOLOCK_EXCL);
277 0 : if (!adoption_performed)
278 0 : xrep_adoption_cancel(&xnc->adoption, 0);
279 : }
280 : return 0;
281 :
282 0 : out_scanlock:
283 0 : mutex_unlock(&xnc->lock);
284 91362510 : out_trans:
285 91362510 : xchk_trans_cancel(sc);
286 91362510 : out_ilock:
287 91362510 : xchk_iunlock(sc, XFS_ILOCK_EXCL);
288 91362510 : if (orphanage_available && (sc->orphanage_ilock_flags & XFS_ILOCK_EXCL))
289 91360506 : xrep_orphanage_iunlock(sc, XFS_ILOCK_EXCL);
290 2004 : out_iolock:
291 91362510 : xchk_iunlock(sc, XFS_IOLOCK_EXCL);
292 91362510 : if (orphanage_available) {
293 91360506 : xrep_orphanage_iunlock(sc, XFS_IOLOCK_EXCL);
294 91360506 : if (!adoption_performed)
295 91360506 : xrep_adoption_cancel(&xnc->adoption, error);
296 : }
297 : return error;
298 : }
299 :
300 : /*
301 : * Try to visit every inode in the filesystem for repairs. Move on if we can't
302 : * grab an inode, since we're still making forward progress.
303 : */
304 : static int
305 : xrep_nlinks_iter(
306 : struct xchk_nlink_ctrs *xnc,
307 : struct xfs_inode **ipp)
308 : {
309 91364514 : int error;
310 :
311 91364514 : do {
312 91364514 : error = xchk_iscan_iter(&xnc->compare_iscan, ipp);
313 91364514 : } while (error == -EBUSY);
314 :
315 91364514 : return error;
316 : }
317 :
318 : /* Commit the new inode link counters. */
319 : int
320 2004 : xrep_nlinks(
321 : struct xfs_scrub *sc)
322 : {
323 2004 : struct xchk_nlink_ctrs *xnc = sc->buf;
324 2004 : int error;
325 :
326 : /*
327 : * We need ftype for an accurate count of the number of child
328 : * subdirectory links. Child subdirectories with a back link (dotdot
329 : * entry) but no forward link are moved to the orphanage, so we cannot
330 : * repair the link count of the parent directory based on the back link
331 : * count alone. Filesystems without ftype support are rare (old V4) so
332 : * we just skip out here.
333 : */
334 2004 : if (!xfs_has_ftype(sc->mp))
335 : return -EOPNOTSUPP;
336 :
337 : /*
338 : * Use the inobt to walk all allocated inodes to compare and fix the
339 : * link counts. Retry iget every tenth of a second for up to 30
340 : * seconds -- even if repair misses a few inodes, we still try to fix
341 : * as many of them as we can.
342 : */
343 2004 : xchk_iscan_start(sc, 30000, 100, &xnc->compare_iscan);
344 2004 : ASSERT(sc->ip == NULL);
345 :
346 182729028 : while ((error = xrep_nlinks_iter(xnc, &sc->ip)) == 1) {
347 : /*
348 : * Commit the scrub transaction so that we can create repair
349 : * transactions with the correct reservations.
350 : */
351 91362510 : xchk_trans_cancel(sc);
352 :
353 91362510 : error = xrep_nlinks_repair_inode(xnc);
354 91362510 : xchk_iscan_mark_visited(&xnc->compare_iscan, sc->ip);
355 91362510 : xchk_irele(sc, sc->ip);
356 91362510 : sc->ip = NULL;
357 91362510 : if (error)
358 : break;
359 :
360 91362510 : if (xchk_should_terminate(sc, &error))
361 : break;
362 :
363 : /*
364 : * Create a new empty transaction so that we can advance the
365 : * iscan cursor without deadlocking if the inobt has a cycle.
366 : * We can only push the inactivation workqueues with an empty
367 : * transaction.
368 : */
369 91362510 : error = xchk_trans_alloc_empty(sc);
370 91362510 : if (error)
371 : break;
372 : }
373 2004 : xchk_iscan_iter_finish(&xnc->compare_iscan);
374 2004 : xchk_iscan_teardown(&xnc->compare_iscan);
375 :
376 2004 : return error;
377 : }
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