1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2022-2023 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_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_inode.h"
14 #include "xfs_dir2.h"
15 #include "xfs_dir2_priv.h"
16 #include "xfs_trace.h"
17 #include "xfs_bmap.h"
18 #include "xfs_trans.h"
19 #include "xfs_error.h"
20 #include "scrub/scrub.h"
21 #include "scrub/common.h"
22 #include "scrub/readdir.h"
23
24 /* Call a function for every entry in a shortform directory. */
25 STATIC int
26 xchk_dir_walk_sf(
27 struct xfs_scrub *sc,
28 struct xfs_inode *dp,
29 xchk_dirent_fn dirent_fn,
30 void *priv)
31 {
32 struct xfs_name name = {
33 .name = ".",
34 .len = 1,
35 .type = XFS_DIR3_FT_DIR,
36 };
37 struct xfs_mount *mp = dp->i_mount;
38 struct xfs_da_geometry *geo = mp->m_dir_geo;
39 struct xfs_dir2_sf_entry *sfep;
40 struct xfs_dir2_sf_hdr *sfp = dp->i_df.if_data;
41 xfs_ino_t ino;
42 xfs_dir2_dataptr_t dapos;
43 unsigned int i;
44 int error;
45
46 ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
47 ASSERT(sfp != NULL);
48
49 /* dot entry */
50 dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
51 geo->data_entry_offset);
52
53 error = dirent_fn(sc, dp, dapos, &name, dp->i_ino, priv);
54 if (error)
55 return error;
56
57 /* dotdot entry */
58 dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
59 geo->data_entry_offset +
60 xfs_dir2_data_entsize(mp, sizeof(".") - 1));
61 ino = xfs_dir2_sf_get_parent_ino(sfp);
62 name.name = "..";
63 name.len = 2;
64
65 error = dirent_fn(sc, dp, dapos, &name, ino, priv);
66 if (error)
67 return error;
68
69 /* iterate everything else */
70 sfep = xfs_dir2_sf_firstentry(sfp);
71 for (i = 0; i < sfp->count; i++) {
72 dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
73 xfs_dir2_sf_get_offset(sfep));
74 ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
75 name.name = sfep->name;
76 name.len = sfep->namelen;
77 name.type = xfs_dir2_sf_get_ftype(mp, sfep);
78
79 error = dirent_fn(sc, dp, dapos, &name, ino, priv);
80 if (error)
81 return error;
82
83 sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
84 }
85
86 return 0;
87 }
88
89 /* Call a function for every entry in a block directory. */
90 STATIC int
91 xchk_dir_walk_block(
92 struct xfs_scrub *sc,
93 struct xfs_inode *dp,
94 xchk_dirent_fn dirent_fn,
95 void *priv)
96 {
97 struct xfs_mount *mp = dp->i_mount;
98 struct xfs_da_geometry *geo = mp->m_dir_geo;
99 struct xfs_buf *bp;
100 unsigned int off, next_off, end;
101 int error;
102
103 error = xfs_dir3_block_read(sc->tp, dp, dp->i_ino, &bp);
104 if (error)
105 return error;
106
107 /* Walk each directory entry. */
108 end = xfs_dir3_data_end_offset(geo, bp->b_addr);
109 for (off = geo->data_entry_offset; off < end; off = next_off) {
110 struct xfs_name name = { };
111 struct xfs_dir2_data_unused *dup = bp->b_addr + off;
112 struct xfs_dir2_data_entry *dep = bp->b_addr + off;
113 xfs_ino_t ino;
114 xfs_dir2_dataptr_t dapos;
115
116 /* Skip an empty entry. */
117 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
118 next_off = off + be16_to_cpu(dup->length);
119 continue;
120 }
121
122 /* Otherwise, find the next entry and report it. */
123 next_off = off + xfs_dir2_data_entsize(mp, dep->namelen);
124 if (next_off > end)
125 break;
126
127 dapos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, off);
128 ino = be64_to_cpu(dep->inumber);
129 name.name = dep->name;
130 name.len = dep->namelen;
131 name.type = xfs_dir2_data_get_ftype(mp, dep);
132
133 error = dirent_fn(sc, dp, dapos, &name, ino, priv);
134 if (error)
135 break;
136 }
137
138 xfs_trans_brelse(sc->tp, bp);
139 return error;
140 }
141
142 /* Read a leaf-format directory buffer. */
143 STATIC int
144 xchk_read_leaf_dir_buf(
145 struct xfs_trans *tp,
146 struct xfs_inode *dp,
147 struct xfs_da_geometry *geo,
148 xfs_dir2_off_t *curoff,
149 struct xfs_buf **bpp)
150 {
151 struct xfs_iext_cursor icur;
152 struct xfs_bmbt_irec map;
153 struct xfs_ifork *ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
154 xfs_dablk_t last_da;
155 xfs_dablk_t map_off;
156 xfs_dir2_off_t new_off;
157
158 *bpp = NULL;
159
160 /*
161 * Look for mapped directory blocks at or above the current offset.
162 * Truncate down to the nearest directory block to start the scanning
163 * operation.
164 */
165 last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
166 map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *curoff));
167
168 if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
169 return 0;
170 if (map.br_startoff >= last_da)
171 return 0;
172 xfs_trim_extent(&map, map_off, last_da - map_off);
173
174 /* Read the directory block of that first mapping. */
175 new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
176 if (new_off > *curoff)
177 *curoff = new_off;
178
179 return xfs_dir3_data_read(tp, dp, dp->i_ino, map.br_startoff, 0, bpp);
180 }
181
182 /* Call a function for every entry in a leaf directory. */
183 STATIC int
184 xchk_dir_walk_leaf(
185 struct xfs_scrub *sc,
186 struct xfs_inode *dp,
187 xchk_dirent_fn dirent_fn,
188 void *priv)
189 {
190 struct xfs_mount *mp = dp->i_mount;
191 struct xfs_da_geometry *geo = mp->m_dir_geo;
192 struct xfs_buf *bp = NULL;
193 xfs_dir2_off_t curoff = 0;
194 unsigned int offset = 0;
195 int error;
196
197 /* Iterate every directory offset in this directory. */
198 while (curoff < XFS_DIR2_LEAF_OFFSET) {
199 struct xfs_name name = { };
200 struct xfs_dir2_data_unused *dup;
201 struct xfs_dir2_data_entry *dep;
202 xfs_ino_t ino;
203 unsigned int length;
204 xfs_dir2_dataptr_t dapos;
205
206 /*
207 * If we have no buffer, or we're off the end of the
208 * current buffer, need to get another one.
209 */
210 if (!bp || offset >= geo->blksize) {
211 if (bp) {
212 xfs_trans_brelse(sc->tp, bp);
213 bp = NULL;
214 }
215
216 error = xchk_read_leaf_dir_buf(sc->tp, dp, geo, &curoff,
217 &bp);
218 if (error || !bp)
219 break;
220
221 /*
222 * Find our position in the block.
223 */
224 offset = geo->data_entry_offset;
225 curoff += geo->data_entry_offset;
226 }
227
228 /* Skip an empty entry. */
229 dup = bp->b_addr + offset;
230 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
231 length = be16_to_cpu(dup->length);
232 offset += length;
233 curoff += length;
234 continue;
235 }
236
237 /* Otherwise, find the next entry and report it. */
238 dep = bp->b_addr + offset;
239 length = xfs_dir2_data_entsize(mp, dep->namelen);
240
241 dapos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
242 ino = be64_to_cpu(dep->inumber);
243 name.name = dep->name;
244 name.len = dep->namelen;
245 name.type = xfs_dir2_data_get_ftype(mp, dep);
246
247 error = dirent_fn(sc, dp, dapos, &name, ino, priv);
248 if (error)
249 break;
250
251 /* Advance to the next entry. */
252 offset += length;
253 curoff += length;
254 }
255
256 if (bp)
257 xfs_trans_brelse(sc->tp, bp);
258 return error;
259 }
260
261 /*
262 * Call a function for every entry in a directory.
263 *
264 * Callers must hold the ILOCK. File types are XFS_DIR3_FT_*.
265 */
266 int
267 xchk_dir_walk(
268 struct xfs_scrub *sc,
269 struct xfs_inode *dp,
270 xchk_dirent_fn dirent_fn,
271 void *priv)
272 {
273 struct xfs_da_args args = {
274 .dp = dp,
275 .geo = dp->i_mount->m_dir_geo,
276 .trans = sc->tp,
277 .owner = dp->i_ino,
278 };
279 int error;
280
281 if (xfs_is_shutdown(dp->i_mount))
282 return -EIO;
283
284 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
285 xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
286
287 switch (xfs_dir2_format(&args, &error)) {
288 case XFS_DIR2_FMT_SF:
289 return xchk_dir_walk_sf(sc, dp, dirent_fn, priv);
290 case XFS_DIR2_FMT_BLOCK:
291 return xchk_dir_walk_block(sc, dp, dirent_fn, priv);
292 case XFS_DIR2_FMT_LEAF:
293 case XFS_DIR2_FMT_NODE:
294 return xchk_dir_walk_leaf(sc, dp, dirent_fn, priv);
295 default:
296 return error;
297 }
298 }
299
300 /*
301 * Look up the inode number for an exact name in a directory.
302 *
303 * Callers must hold the ILOCK. File types are XFS_DIR3_FT_*. Names are not
304 * checked for correctness.
305 */
306 int
307 xchk_dir_lookup(
308 struct xfs_scrub *sc,
309 struct xfs_inode *dp,
310 const struct xfs_name *name,
311 xfs_ino_t *ino)
312 {
313 struct xfs_da_args args = {
314 .dp = dp,
315 .geo = dp->i_mount->m_dir_geo,
316 .trans = sc->tp,
317 .name = name->name,
318 .namelen = name->len,
319 .filetype = name->type,
320 .hashval = xfs_dir2_hashname(dp->i_mount, name),
321 .whichfork = XFS_DATA_FORK,
322 .op_flags = XFS_DA_OP_OKNOENT,
323 .owner = dp->i_ino,
324 };
325 int error;
326
327 if (xfs_is_shutdown(dp->i_mount))
328 return -EIO;
329
330 /*
331 * A temporary directory's block headers are written with the owner
332 * set to sc->ip, so we must switch the owner here for the lookup.
333 */
334 if (dp == sc->tempip)
335 args.owner = sc->ip->i_ino;
336
337 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
338 xfs_assert_ilocked(dp, XFS_ILOCK_SHARED | XFS_ILOCK_EXCL);
339
340 error = xfs_dir_lookup_args(&args);
341 if (!error)
342 *ino = args.inumber;
343 return error;
344 }
345
346 /*
347 * Try to grab the IOLOCK and ILOCK of sc->ip and ip, returning @ip's lock
348 * state. The caller may have a transaction, so we must use trylock for both
349 * IOLOCKs.
350 */
351 static inline unsigned int
352 xchk_dir_trylock_both(
353 struct xfs_scrub *sc,
354 struct xfs_inode *ip)
355 {
356 if (!xchk_ilock_nowait(sc, XFS_IOLOCK_EXCL))
357 return 0;
358
359 if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED))
360 goto parent_iolock;
361
362 xchk_ilock(sc, XFS_ILOCK_EXCL);
363 if (!xfs_ilock_nowait(ip, XFS_ILOCK_EXCL))
364 goto parent_ilock;
365
366 return XFS_IOLOCK_SHARED | XFS_ILOCK_EXCL;
367
368 parent_ilock:
369 xchk_iunlock(sc, XFS_ILOCK_EXCL);
370 xfs_iunlock(ip, XFS_IOLOCK_SHARED);
371 parent_iolock:
372 xchk_iunlock(sc, XFS_IOLOCK_EXCL);
373 return 0;
374 }
375
376 /*
377 * Try for a limited time to grab the IOLOCK and ILOCK of both the scrub target
378 * (@sc->ip) and the inode at the other end (@ip) of a directory or parent
379 * pointer link so that we can check that link.
380 *
381 * We do not know ahead of time that the directory tree is /not/ corrupt, so we
382 * cannot use the "lock two inode" functions because we do not know that there
383 * is not a racing thread trying to take the locks in opposite order. First
384 * take IOLOCK_EXCL of the scrub target, and then try to take IOLOCK_SHARED
385 * of @ip to synchronize with the VFS. Next, take ILOCK_EXCL of the scrub
386 * target and @ip to synchronize with XFS.
387 *
388 * If the trylocks succeed, *lockmode will be set to the locks held for @ip;
389 * @sc->ilock_flags will be set for the locks held for @sc->ip; and zero will
390 * be returned. If not, returns -EDEADLOCK to try again; or -ETIMEDOUT if
391 * XCHK_TRY_HARDER was set. Returns -EINTR if the process has been killed.
392 */
393 int
394 xchk_dir_trylock_for_pptrs(
395 struct xfs_scrub *sc,
396 struct xfs_inode *ip,
397 unsigned int *lockmode)
398 {
399 unsigned int nr;
400 int error = 0;
401
402 ASSERT(sc->ilock_flags == 0);
403
404 for (nr = 0; nr < HZ; nr++) {
405 *lockmode = xchk_dir_trylock_both(sc, ip);
406 if (*lockmode)
407 return 0;
408
409 if (xchk_should_terminate(sc, &error))
410 return error;
411
412 delay(1);
413 }
414
415 if (sc->flags & XCHK_TRY_HARDER) {
416 xchk_set_incomplete(sc);
417 return -ETIMEDOUT;
418 }
419
420 return -EDEADLOCK;
421 }
422
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