1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
4 * Copyright (c) 2013 Red Hat, Inc.
5 * All Rights Reserved.
6 */
7 #include "xfs.h"
8 #include "xfs_fs.h"
9 #include "xfs_shared.h"
10 #include "xfs_format.h"
11 #include "xfs_log_format.h"
12 #include "xfs_trans_resv.h"
13 #include "xfs_mount.h"
14 #include "xfs_inode.h"
15 #include "xfs_dir2.h"
16 #include "xfs_dir2_priv.h"
17 #include "xfs_trace.h"
18 #include "xfs_bmap.h"
19 #include "xfs_trans.h"
20 #include "xfs_error.h"
21 #include "xfs_health.h"
22
23 /*
24 * Directory file type support functions
25 */
26 static unsigned char xfs_dir3_filetype_table[] = {
27 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
28 DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
29 };
30
31 unsigned char
32 xfs_dir3_get_dtype(
33 struct xfs_mount *mp,
34 uint8_t filetype)
35 {
36 if (!xfs_has_ftype(mp))
37 return DT_UNKNOWN;
38
39 if (filetype >= XFS_DIR3_FT_MAX)
40 return DT_UNKNOWN;
41
42 return xfs_dir3_filetype_table[filetype];
43 }
44
45 STATIC int
46 xfs_dir2_sf_getdents(
47 struct xfs_da_args *args,
48 struct dir_context *ctx)
49 {
50 int i; /* shortform entry number */
51 struct xfs_inode *dp = args->dp; /* incore directory inode */
52 struct xfs_mount *mp = dp->i_mount;
53 xfs_dir2_dataptr_t off; /* current entry's offset */
54 xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
55 struct xfs_dir2_sf_hdr *sfp = dp->i_df.if_data;
56 xfs_dir2_dataptr_t dot_offset;
57 xfs_dir2_dataptr_t dotdot_offset;
58 xfs_ino_t ino;
59 struct xfs_da_geometry *geo = args->geo;
60
61 ASSERT(dp->i_df.if_format == XFS_DINODE_FMT_LOCAL);
62 ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
63 ASSERT(sfp != NULL);
64
65 /*
66 * If the block number in the offset is out of range, we're done.
67 */
68 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
69 return 0;
70
71 /*
72 * Precalculate offsets for "." and ".." as we will always need them.
73 * This relies on the fact that directories always start with the
74 * entries for "." and "..".
75 */
76 dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
77 geo->data_entry_offset);
78 dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
79 geo->data_entry_offset +
80 xfs_dir2_data_entsize(mp, sizeof(".") - 1));
81
82 /*
83 * Put . entry unless we're starting past it.
84 */
85 if (ctx->pos <= dot_offset) {
86 ctx->pos = dot_offset & 0x7fffffff;
87 if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
88 return 0;
89 }
90
91 /*
92 * Put .. entry unless we're starting past it.
93 */
94 if (ctx->pos <= dotdot_offset) {
95 ino = xfs_dir2_sf_get_parent_ino(sfp);
96 ctx->pos = dotdot_offset & 0x7fffffff;
97 if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
98 return 0;
99 }
100
101 /*
102 * Loop while there are more entries and put'ing works.
103 */
104 sfep = xfs_dir2_sf_firstentry(sfp);
105 for (i = 0; i < sfp->count; i++) {
106 uint8_t filetype;
107
108 off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
109 xfs_dir2_sf_get_offset(sfep));
110
111 if (ctx->pos > off) {
112 sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
113 continue;
114 }
115
116 ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
117 filetype = xfs_dir2_sf_get_ftype(mp, sfep);
118 ctx->pos = off & 0x7fffffff;
119 if (XFS_IS_CORRUPT(dp->i_mount,
120 !xfs_dir2_namecheck(sfep->name,
121 sfep->namelen))) {
122 xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
123 return -EFSCORRUPTED;
124 }
125 if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
126 xfs_dir3_get_dtype(mp, filetype)))
127 return 0;
128 sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
129 }
130
131 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
132 0x7fffffff;
133 return 0;
134 }
135
136 /*
137 * Readdir for block directories.
138 */
139 STATIC int
140 xfs_dir2_block_getdents(
141 struct xfs_da_args *args,
142 struct dir_context *ctx,
143 unsigned int *lock_mode)
144 {
145 struct xfs_inode *dp = args->dp; /* incore directory inode */
146 struct xfs_buf *bp; /* buffer for block */
147 int error; /* error return value */
148 int wantoff; /* starting block offset */
149 xfs_off_t cook;
150 struct xfs_da_geometry *geo = args->geo;
151 unsigned int offset, next_offset;
152 unsigned int end;
153
154 /*
155 * If the block number in the offset is out of range, we're done.
156 */
157 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
158 return 0;
159
160 error = xfs_dir3_block_read(args->trans, dp, args->owner, &bp);
161 if (error)
162 return error;
163
164 xfs_iunlock(dp, *lock_mode);
165 *lock_mode = 0;
166
167 /*
168 * Extract the byte offset we start at from the seek pointer.
169 * We'll skip entries before this.
170 */
171 wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
172 xfs_dir3_data_check(dp, bp);
173
174 /*
175 * Loop over the data portion of the block.
176 * Each object is a real entry (dep) or an unused one (dup).
177 */
178 end = xfs_dir3_data_end_offset(geo, bp->b_addr);
179 for (offset = geo->data_entry_offset;
180 offset < end;
181 offset = next_offset) {
182 struct xfs_dir2_data_unused *dup = bp->b_addr + offset;
183 struct xfs_dir2_data_entry *dep = bp->b_addr + offset;
184 uint8_t filetype;
185
186 /*
187 * Unused, skip it.
188 */
189 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
190 next_offset = offset + be16_to_cpu(dup->length);
191 continue;
192 }
193
194 /*
195 * Bump pointer for the next iteration.
196 */
197 next_offset = offset +
198 xfs_dir2_data_entsize(dp->i_mount, dep->namelen);
199
200 /*
201 * The entry is before the desired starting point, skip it.
202 */
203 if (offset < wantoff)
204 continue;
205
206 cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset);
207
208 ctx->pos = cook & 0x7fffffff;
209 filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep);
210 /*
211 * If it didn't fit, set the final offset to here & return.
212 */
213 if (XFS_IS_CORRUPT(dp->i_mount,
214 !xfs_dir2_namecheck(dep->name,
215 dep->namelen))) {
216 xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
217 error = -EFSCORRUPTED;
218 goto out_rele;
219 }
220 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
221 be64_to_cpu(dep->inumber),
222 xfs_dir3_get_dtype(dp->i_mount, filetype)))
223 goto out_rele;
224 }
225
226 /*
227 * Reached the end of the block.
228 * Set the offset to a non-existent block 1 and return.
229 */
230 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
231 0x7fffffff;
232 out_rele:
233 xfs_trans_brelse(args->trans, bp);
234 return error;
235 }
236
237 /*
238 * Read a directory block and initiate readahead for blocks beyond that.
239 * We maintain a sliding readahead window of the remaining space in the
240 * buffer rounded up to the nearest block.
241 */
242 STATIC int
243 xfs_dir2_leaf_readbuf(
244 struct xfs_da_args *args,
245 size_t bufsize,
246 xfs_dir2_off_t *cur_off,
247 xfs_dablk_t *ra_blk,
248 struct xfs_buf **bpp)
249 {
250 struct xfs_inode *dp = args->dp;
251 struct xfs_buf *bp = NULL;
252 struct xfs_da_geometry *geo = args->geo;
253 struct xfs_ifork *ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
254 struct xfs_bmbt_irec map;
255 struct blk_plug plug;
256 xfs_dir2_off_t new_off;
257 xfs_dablk_t next_ra;
258 xfs_dablk_t map_off;
259 xfs_dablk_t last_da;
260 struct xfs_iext_cursor icur;
261 int ra_want;
262 int error = 0;
263
264 error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
265 if (error)
266 goto out;
267
268 /*
269 * Look for mapped directory blocks at or above the current offset.
270 * Truncate down to the nearest directory block to start the scanning
271 * operation.
272 */
273 last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
274 map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
275 if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
276 goto out;
277 if (map.br_startoff >= last_da)
278 goto out;
279 xfs_trim_extent(&map, map_off, last_da - map_off);
280
281 /* Read the directory block of that first mapping. */
282 new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
283 if (new_off > *cur_off)
284 *cur_off = new_off;
285 error = xfs_dir3_data_read(args->trans, dp, args->owner,
286 map.br_startoff, 0, &bp);
287 if (error)
288 goto out;
289
290 /*
291 * Start readahead for the next bufsize's worth of dir data blocks.
292 * We may have already issued readahead for some of that range;
293 * ra_blk tracks the last block we tried to read(ahead).
294 */
295 ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
296 if (*ra_blk >= last_da)
297 goto out;
298 else if (*ra_blk == 0)
299 *ra_blk = map.br_startoff;
300 next_ra = map.br_startoff + geo->fsbcount;
301 if (next_ra >= last_da)
302 goto out_no_ra;
303 if (map.br_blockcount < geo->fsbcount &&
304 !xfs_iext_next_extent(ifp, &icur, &map))
305 goto out_no_ra;
306 if (map.br_startoff >= last_da)
307 goto out_no_ra;
308 xfs_trim_extent(&map, next_ra, last_da - next_ra);
309
310 /* Start ra for each dir (not fs) block that has a mapping. */
311 blk_start_plug(&plug);
312 while (ra_want > 0) {
313 next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
314 while (ra_want > 0 &&
315 next_ra < map.br_startoff + map.br_blockcount) {
316 if (next_ra >= last_da) {
317 *ra_blk = last_da;
318 break;
319 }
320 if (next_ra > *ra_blk) {
321 xfs_dir3_data_readahead(dp, next_ra,
322 XFS_DABUF_MAP_HOLE_OK);
323 *ra_blk = next_ra;
324 }
325 ra_want -= geo->fsbcount;
326 next_ra += geo->fsbcount;
327 }
328 if (!xfs_iext_next_extent(ifp, &icur, &map)) {
329 *ra_blk = last_da;
330 break;
331 }
332 }
333 blk_finish_plug(&plug);
334
335 out:
336 *bpp = bp;
337 return error;
338 out_no_ra:
339 *ra_blk = last_da;
340 goto out;
341 }
342
343 /*
344 * Getdents (readdir) for leaf and node directories.
345 * This reads the data blocks only, so is the same for both forms.
346 */
347 STATIC int
348 xfs_dir2_leaf_getdents(
349 struct xfs_da_args *args,
350 struct dir_context *ctx,
351 size_t bufsize,
352 unsigned int *lock_mode)
353 {
354 struct xfs_inode *dp = args->dp;
355 struct xfs_mount *mp = dp->i_mount;
356 struct xfs_buf *bp = NULL; /* data block buffer */
357 xfs_dir2_data_entry_t *dep; /* data entry */
358 xfs_dir2_data_unused_t *dup; /* unused entry */
359 struct xfs_da_geometry *geo = args->geo;
360 xfs_dablk_t rablk = 0; /* current readahead block */
361 xfs_dir2_off_t curoff; /* current overall offset */
362 int length; /* temporary length value */
363 int byteoff; /* offset in current block */
364 unsigned int offset = 0;
365 int error = 0; /* error return value */
366
367 /*
368 * If the offset is at or past the largest allowed value,
369 * give up right away.
370 */
371 if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
372 return 0;
373
374 /*
375 * Inside the loop we keep the main offset value as a byte offset
376 * in the directory file.
377 */
378 curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
379
380 /*
381 * Loop over directory entries until we reach the end offset.
382 * Get more blocks and readahead as necessary.
383 */
384 while (curoff < XFS_DIR2_LEAF_OFFSET) {
385 uint8_t filetype;
386
387 /*
388 * If we have no buffer, or we're off the end of the
389 * current buffer, need to get another one.
390 */
391 if (!bp || offset >= geo->blksize) {
392 if (bp) {
393 xfs_trans_brelse(args->trans, bp);
394 bp = NULL;
395 }
396
397 if (*lock_mode == 0)
398 *lock_mode = xfs_ilock_data_map_shared(dp);
399 error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
400 &rablk, &bp);
401 if (error || !bp)
402 break;
403
404 xfs_iunlock(dp, *lock_mode);
405 *lock_mode = 0;
406
407 xfs_dir3_data_check(dp, bp);
408 /*
409 * Find our position in the block.
410 */
411 offset = geo->data_entry_offset;
412 byteoff = xfs_dir2_byte_to_off(geo, curoff);
413 /*
414 * Skip past the header.
415 */
416 if (byteoff == 0)
417 curoff += geo->data_entry_offset;
418 /*
419 * Skip past entries until we reach our offset.
420 */
421 else {
422 while (offset < byteoff) {
423 dup = bp->b_addr + offset;
424
425 if (be16_to_cpu(dup->freetag)
426 == XFS_DIR2_DATA_FREE_TAG) {
427
428 length = be16_to_cpu(dup->length);
429 offset += length;
430 continue;
431 }
432 dep = bp->b_addr + offset;
433 length = xfs_dir2_data_entsize(mp,
434 dep->namelen);
435 offset += length;
436 }
437 /*
438 * Now set our real offset.
439 */
440 curoff =
441 xfs_dir2_db_off_to_byte(geo,
442 xfs_dir2_byte_to_db(geo, curoff),
443 offset);
444 if (offset >= geo->blksize)
445 continue;
446 }
447 }
448
449 /*
450 * We have a pointer to an entry. Is it a live one?
451 */
452 dup = bp->b_addr + offset;
453
454 /*
455 * No, it's unused, skip over it.
456 */
457 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
458 length = be16_to_cpu(dup->length);
459 offset += length;
460 curoff += length;
461 continue;
462 }
463
464 dep = bp->b_addr + offset;
465 length = xfs_dir2_data_entsize(mp, dep->namelen);
466 filetype = xfs_dir2_data_get_ftype(mp, dep);
467
468 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
469 if (XFS_IS_CORRUPT(dp->i_mount,
470 !xfs_dir2_namecheck(dep->name,
471 dep->namelen))) {
472 xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
473 error = -EFSCORRUPTED;
474 break;
475 }
476 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
477 be64_to_cpu(dep->inumber),
478 xfs_dir3_get_dtype(dp->i_mount, filetype)))
479 break;
480
481 /*
482 * Advance to next entry in the block.
483 */
484 offset += length;
485 curoff += length;
486 /* bufsize may have just been a guess; don't go negative */
487 bufsize = bufsize > length ? bufsize - length : 0;
488 }
489
490 /*
491 * All done. Set output offset value to current offset.
492 */
493 if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
494 ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
495 else
496 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
497 if (bp)
498 xfs_trans_brelse(args->trans, bp);
499 return error;
500 }
501
502 /*
503 * Read a directory.
504 *
505 * If supplied, the transaction collects locked dir buffers to avoid
506 * nested buffer deadlocks. This function does not dirty the
507 * transaction. The caller must hold the IOLOCK (shared or exclusive)
508 * before calling this function.
509 */
510 int
511 xfs_readdir(
512 struct xfs_trans *tp,
513 struct xfs_inode *dp,
514 struct dir_context *ctx,
515 size_t bufsize)
516 {
517 struct xfs_da_args args = { NULL };
518 unsigned int lock_mode;
519 int error;
520
521 trace_xfs_readdir(dp);
522
523 if (xfs_is_shutdown(dp->i_mount))
524 return -EIO;
525 if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
526 return -EIO;
527
528 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
529 xfs_assert_ilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL);
530 XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
531
532 args.dp = dp;
533 args.geo = dp->i_mount->m_dir_geo;
534 args.trans = tp;
535 args.owner = dp->i_ino;
536
537 if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
538 return xfs_dir2_sf_getdents(&args, ctx);
539
540 lock_mode = xfs_ilock_data_map_shared(dp);
541 switch (xfs_dir2_format(&args, &error)) {
542 case XFS_DIR2_FMT_BLOCK:
543 error = xfs_dir2_block_getdents(&args, ctx, &lock_mode);
544 break;
545 case XFS_DIR2_FMT_LEAF:
546 case XFS_DIR2_FMT_NODE:
547 error = xfs_dir2_leaf_getdents(&args, ctx, bufsize, &lock_mode);
548 break;
549 default:
550 break;
551 }
552
553 if (lock_mode)
554 xfs_iunlock(dp, lock_mode);
555 return error;
556 }
557
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