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 | |
22 | /* |
23 | * Directory file type support functions |
24 | */ |
25 | static unsigned char xfs_dir3_filetype_table[] = { |
26 | DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, |
27 | DT_FIFO, DT_SOCK, DT_LNK, DT_WHT, |
28 | }; |
29 | |
30 | unsigned char |
31 | xfs_dir3_get_dtype( |
32 | struct xfs_mount *mp, |
33 | uint8_t filetype) |
34 | { |
35 | if (!xfs_has_ftype(mp)) |
36 | return DT_UNKNOWN; |
37 | |
38 | if (filetype >= XFS_DIR3_FT_MAX) |
39 | return DT_UNKNOWN; |
40 | |
41 | return xfs_dir3_filetype_table[filetype]; |
42 | } |
43 | |
44 | STATIC int |
45 | xfs_dir2_sf_getdents( |
46 | struct xfs_da_args *args, |
47 | struct dir_context *ctx) |
48 | { |
49 | int i; /* shortform entry number */ |
50 | struct xfs_inode *dp = args->dp; /* incore directory inode */ |
51 | struct xfs_mount *mp = dp->i_mount; |
52 | xfs_dir2_dataptr_t off; /* current entry's offset */ |
53 | xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */ |
54 | xfs_dir2_sf_hdr_t *sfp; /* shortform structure */ |
55 | xfs_dir2_dataptr_t dot_offset; |
56 | xfs_dir2_dataptr_t dotdot_offset; |
57 | xfs_ino_t ino; |
58 | struct xfs_da_geometry *geo = args->geo; |
59 | |
60 | ASSERT(dp->i_df.if_format == XFS_DINODE_FMT_LOCAL); |
61 | ASSERT(dp->i_df.if_bytes == dp->i_disk_size); |
62 | ASSERT(dp->i_df.if_u1.if_data != NULL); |
63 | |
64 | sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data; |
65 | |
66 | /* |
67 | * If the block number in the offset is out of range, we're done. |
68 | */ |
69 | if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk) |
70 | return 0; |
71 | |
72 | /* |
73 | * Precalculate offsets for "." and ".." as we will always need them. |
74 | * This relies on the fact that directories always start with the |
75 | * entries for "." and "..". |
76 | */ |
77 | dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, |
78 | geo->data_entry_offset); |
79 | dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, |
80 | geo->data_entry_offset + |
81 | xfs_dir2_data_entsize(mp, sizeof("." ) - 1)); |
82 | |
83 | /* |
84 | * Put . entry unless we're starting past it. |
85 | */ |
86 | if (ctx->pos <= dot_offset) { |
87 | ctx->pos = dot_offset & 0x7fffffff; |
88 | if (!dir_emit(ctx, name: "." , namelen: 1, ino: dp->i_ino, DT_DIR)) |
89 | return 0; |
90 | } |
91 | |
92 | /* |
93 | * Put .. entry unless we're starting past it. |
94 | */ |
95 | if (ctx->pos <= dotdot_offset) { |
96 | ino = xfs_dir2_sf_get_parent_ino(sfp); |
97 | ctx->pos = dotdot_offset & 0x7fffffff; |
98 | if (!dir_emit(ctx, name: ".." , namelen: 2, ino, DT_DIR)) |
99 | return 0; |
100 | } |
101 | |
102 | /* |
103 | * Loop while there are more entries and put'ing works. |
104 | */ |
105 | sfep = xfs_dir2_sf_firstentry(sfp); |
106 | for (i = 0; i < sfp->count; i++) { |
107 | uint8_t filetype; |
108 | |
109 | off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, |
110 | xfs_dir2_sf_get_offset(sfep)); |
111 | |
112 | if (ctx->pos > off) { |
113 | sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep); |
114 | continue; |
115 | } |
116 | |
117 | ino = xfs_dir2_sf_get_ino(mp, sfp, sfep); |
118 | filetype = xfs_dir2_sf_get_ftype(mp, sfep); |
119 | ctx->pos = off & 0x7fffffff; |
120 | if (XFS_IS_CORRUPT(dp->i_mount, |
121 | !xfs_dir2_namecheck(sfep->name, |
122 | sfep->namelen))) |
123 | return -EFSCORRUPTED; |
124 | if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino, |
125 | xfs_dir3_get_dtype(mp, filetype))) |
126 | return 0; |
127 | sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep); |
128 | } |
129 | |
130 | ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) & |
131 | 0x7fffffff; |
132 | return 0; |
133 | } |
134 | |
135 | /* |
136 | * Readdir for block directories. |
137 | */ |
138 | STATIC int |
139 | xfs_dir2_block_getdents( |
140 | struct xfs_da_args *args, |
141 | struct dir_context *ctx, |
142 | unsigned int *lock_mode) |
143 | { |
144 | struct xfs_inode *dp = args->dp; /* incore directory inode */ |
145 | struct xfs_buf *bp; /* buffer for block */ |
146 | int error; /* error return value */ |
147 | int wantoff; /* starting block offset */ |
148 | xfs_off_t cook; |
149 | struct xfs_da_geometry *geo = args->geo; |
150 | unsigned int offset, next_offset; |
151 | unsigned int end; |
152 | |
153 | /* |
154 | * If the block number in the offset is out of range, we're done. |
155 | */ |
156 | if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk) |
157 | return 0; |
158 | |
159 | error = xfs_dir3_block_read(args->trans, dp, &bp); |
160 | if (error) |
161 | return error; |
162 | |
163 | xfs_iunlock(dp, *lock_mode); |
164 | *lock_mode = 0; |
165 | |
166 | /* |
167 | * Extract the byte offset we start at from the seek pointer. |
168 | * We'll skip entries before this. |
169 | */ |
170 | wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos); |
171 | xfs_dir3_data_check(dp, bp); |
172 | |
173 | /* |
174 | * Loop over the data portion of the block. |
175 | * Each object is a real entry (dep) or an unused one (dup). |
176 | */ |
177 | end = xfs_dir3_data_end_offset(geo, bp->b_addr); |
178 | for (offset = geo->data_entry_offset; |
179 | offset < end; |
180 | offset = next_offset) { |
181 | struct xfs_dir2_data_unused *dup = bp->b_addr + offset; |
182 | struct xfs_dir2_data_entry *dep = bp->b_addr + offset; |
183 | uint8_t filetype; |
184 | |
185 | /* |
186 | * Unused, skip it. |
187 | */ |
188 | if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) { |
189 | next_offset = offset + be16_to_cpu(dup->length); |
190 | continue; |
191 | } |
192 | |
193 | /* |
194 | * Bump pointer for the next iteration. |
195 | */ |
196 | next_offset = offset + |
197 | xfs_dir2_data_entsize(dp->i_mount, dep->namelen); |
198 | |
199 | /* |
200 | * The entry is before the desired starting point, skip it. |
201 | */ |
202 | if (offset < wantoff) |
203 | continue; |
204 | |
205 | cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset); |
206 | |
207 | ctx->pos = cook & 0x7fffffff; |
208 | filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep); |
209 | /* |
210 | * If it didn't fit, set the final offset to here & return. |
211 | */ |
212 | if (XFS_IS_CORRUPT(dp->i_mount, |
213 | !xfs_dir2_namecheck(dep->name, |
214 | dep->namelen))) { |
215 | error = -EFSCORRUPTED; |
216 | goto out_rele; |
217 | } |
218 | if (!dir_emit(ctx, name: (char *)dep->name, namelen: dep->namelen, |
219 | be64_to_cpu(dep->inumber), |
220 | type: xfs_dir3_get_dtype(mp: dp->i_mount, filetype))) |
221 | goto out_rele; |
222 | } |
223 | |
224 | /* |
225 | * Reached the end of the block. |
226 | * Set the offset to a non-existent block 1 and return. |
227 | */ |
228 | ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) & |
229 | 0x7fffffff; |
230 | out_rele: |
231 | xfs_trans_brelse(args->trans, bp); |
232 | return error; |
233 | } |
234 | |
235 | /* |
236 | * Read a directory block and initiate readahead for blocks beyond that. |
237 | * We maintain a sliding readahead window of the remaining space in the |
238 | * buffer rounded up to the nearest block. |
239 | */ |
240 | STATIC int |
241 | xfs_dir2_leaf_readbuf( |
242 | struct xfs_da_args *args, |
243 | size_t bufsize, |
244 | xfs_dir2_off_t *cur_off, |
245 | xfs_dablk_t *ra_blk, |
246 | struct xfs_buf **bpp) |
247 | { |
248 | struct xfs_inode *dp = args->dp; |
249 | struct xfs_buf *bp = NULL; |
250 | struct xfs_da_geometry *geo = args->geo; |
251 | struct xfs_ifork *ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK); |
252 | struct xfs_bmbt_irec map; |
253 | struct blk_plug plug; |
254 | xfs_dir2_off_t new_off; |
255 | xfs_dablk_t next_ra; |
256 | xfs_dablk_t map_off; |
257 | xfs_dablk_t last_da; |
258 | struct xfs_iext_cursor icur; |
259 | int ra_want; |
260 | int error = 0; |
261 | |
262 | error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK); |
263 | if (error) |
264 | goto out; |
265 | |
266 | /* |
267 | * Look for mapped directory blocks at or above the current offset. |
268 | * Truncate down to the nearest directory block to start the scanning |
269 | * operation. |
270 | */ |
271 | last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET); |
272 | map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off)); |
273 | if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map)) |
274 | goto out; |
275 | if (map.br_startoff >= last_da) |
276 | goto out; |
277 | xfs_trim_extent(&map, map_off, last_da - map_off); |
278 | |
279 | /* Read the directory block of that first mapping. */ |
280 | new_off = xfs_dir2_da_to_byte(geo, map.br_startoff); |
281 | if (new_off > *cur_off) |
282 | *cur_off = new_off; |
283 | error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, 0, &bp); |
284 | if (error) |
285 | goto out; |
286 | |
287 | /* |
288 | * Start readahead for the next bufsize's worth of dir data blocks. |
289 | * We may have already issued readahead for some of that range; |
290 | * ra_blk tracks the last block we tried to read(ahead). |
291 | */ |
292 | ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog)); |
293 | if (*ra_blk >= last_da) |
294 | goto out; |
295 | else if (*ra_blk == 0) |
296 | *ra_blk = map.br_startoff; |
297 | next_ra = map.br_startoff + geo->fsbcount; |
298 | if (next_ra >= last_da) |
299 | goto out_no_ra; |
300 | if (map.br_blockcount < geo->fsbcount && |
301 | !xfs_iext_next_extent(ifp, &icur, &map)) |
302 | goto out_no_ra; |
303 | if (map.br_startoff >= last_da) |
304 | goto out_no_ra; |
305 | xfs_trim_extent(&map, next_ra, last_da - next_ra); |
306 | |
307 | /* Start ra for each dir (not fs) block that has a mapping. */ |
308 | blk_start_plug(&plug); |
309 | while (ra_want > 0) { |
310 | next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount); |
311 | while (ra_want > 0 && |
312 | next_ra < map.br_startoff + map.br_blockcount) { |
313 | if (next_ra >= last_da) { |
314 | *ra_blk = last_da; |
315 | break; |
316 | } |
317 | if (next_ra > *ra_blk) { |
318 | xfs_dir3_data_readahead(dp, next_ra, |
319 | XFS_DABUF_MAP_HOLE_OK); |
320 | *ra_blk = next_ra; |
321 | } |
322 | ra_want -= geo->fsbcount; |
323 | next_ra += geo->fsbcount; |
324 | } |
325 | if (!xfs_iext_next_extent(ifp, &icur, &map)) { |
326 | *ra_blk = last_da; |
327 | break; |
328 | } |
329 | } |
330 | blk_finish_plug(&plug); |
331 | |
332 | out: |
333 | *bpp = bp; |
334 | return error; |
335 | out_no_ra: |
336 | *ra_blk = last_da; |
337 | goto out; |
338 | } |
339 | |
340 | /* |
341 | * Getdents (readdir) for leaf and node directories. |
342 | * This reads the data blocks only, so is the same for both forms. |
343 | */ |
344 | STATIC int |
345 | xfs_dir2_leaf_getdents( |
346 | struct xfs_da_args *args, |
347 | struct dir_context *ctx, |
348 | size_t bufsize, |
349 | unsigned int *lock_mode) |
350 | { |
351 | struct xfs_inode *dp = args->dp; |
352 | struct xfs_mount *mp = dp->i_mount; |
353 | struct xfs_buf *bp = NULL; /* data block buffer */ |
354 | xfs_dir2_data_entry_t *dep; /* data entry */ |
355 | xfs_dir2_data_unused_t *dup; /* unused entry */ |
356 | struct xfs_da_geometry *geo = args->geo; |
357 | xfs_dablk_t rablk = 0; /* current readahead block */ |
358 | xfs_dir2_off_t curoff; /* current overall offset */ |
359 | int length; /* temporary length value */ |
360 | int byteoff; /* offset in current block */ |
361 | unsigned int offset = 0; |
362 | int error = 0; /* error return value */ |
363 | |
364 | /* |
365 | * If the offset is at or past the largest allowed value, |
366 | * give up right away. |
367 | */ |
368 | if (ctx->pos >= XFS_DIR2_MAX_DATAPTR) |
369 | return 0; |
370 | |
371 | /* |
372 | * Inside the loop we keep the main offset value as a byte offset |
373 | * in the directory file. |
374 | */ |
375 | curoff = xfs_dir2_dataptr_to_byte(ctx->pos); |
376 | |
377 | /* |
378 | * Loop over directory entries until we reach the end offset. |
379 | * Get more blocks and readahead as necessary. |
380 | */ |
381 | while (curoff < XFS_DIR2_LEAF_OFFSET) { |
382 | uint8_t filetype; |
383 | |
384 | /* |
385 | * If we have no buffer, or we're off the end of the |
386 | * current buffer, need to get another one. |
387 | */ |
388 | if (!bp || offset >= geo->blksize) { |
389 | if (bp) { |
390 | xfs_trans_brelse(args->trans, bp); |
391 | bp = NULL; |
392 | } |
393 | |
394 | if (*lock_mode == 0) |
395 | *lock_mode = xfs_ilock_data_map_shared(dp); |
396 | error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff, |
397 | &rablk, &bp); |
398 | if (error || !bp) |
399 | break; |
400 | |
401 | xfs_iunlock(dp, *lock_mode); |
402 | *lock_mode = 0; |
403 | |
404 | xfs_dir3_data_check(dp, bp); |
405 | /* |
406 | * Find our position in the block. |
407 | */ |
408 | offset = geo->data_entry_offset; |
409 | byteoff = xfs_dir2_byte_to_off(geo, curoff); |
410 | /* |
411 | * Skip past the header. |
412 | */ |
413 | if (byteoff == 0) |
414 | curoff += geo->data_entry_offset; |
415 | /* |
416 | * Skip past entries until we reach our offset. |
417 | */ |
418 | else { |
419 | while (offset < byteoff) { |
420 | dup = bp->b_addr + offset; |
421 | |
422 | if (be16_to_cpu(dup->freetag) |
423 | == XFS_DIR2_DATA_FREE_TAG) { |
424 | |
425 | length = be16_to_cpu(dup->length); |
426 | offset += length; |
427 | continue; |
428 | } |
429 | dep = bp->b_addr + offset; |
430 | length = xfs_dir2_data_entsize(mp, |
431 | dep->namelen); |
432 | offset += length; |
433 | } |
434 | /* |
435 | * Now set our real offset. |
436 | */ |
437 | curoff = |
438 | xfs_dir2_db_off_to_byte(geo, |
439 | xfs_dir2_byte_to_db(geo, curoff), |
440 | offset); |
441 | if (offset >= geo->blksize) |
442 | continue; |
443 | } |
444 | } |
445 | |
446 | /* |
447 | * We have a pointer to an entry. Is it a live one? |
448 | */ |
449 | dup = bp->b_addr + offset; |
450 | |
451 | /* |
452 | * No, it's unused, skip over it. |
453 | */ |
454 | if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) { |
455 | length = be16_to_cpu(dup->length); |
456 | offset += length; |
457 | curoff += length; |
458 | continue; |
459 | } |
460 | |
461 | dep = bp->b_addr + offset; |
462 | length = xfs_dir2_data_entsize(mp, dep->namelen); |
463 | filetype = xfs_dir2_data_get_ftype(mp, dep); |
464 | |
465 | ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff; |
466 | if (XFS_IS_CORRUPT(dp->i_mount, |
467 | !xfs_dir2_namecheck(dep->name, |
468 | dep->namelen))) { |
469 | error = -EFSCORRUPTED; |
470 | break; |
471 | } |
472 | if (!dir_emit(ctx, (char *)dep->name, dep->namelen, |
473 | be64_to_cpu(dep->inumber), |
474 | xfs_dir3_get_dtype(dp->i_mount, filetype))) |
475 | break; |
476 | |
477 | /* |
478 | * Advance to next entry in the block. |
479 | */ |
480 | offset += length; |
481 | curoff += length; |
482 | /* bufsize may have just been a guess; don't go negative */ |
483 | bufsize = bufsize > length ? bufsize - length : 0; |
484 | } |
485 | |
486 | /* |
487 | * All done. Set output offset value to current offset. |
488 | */ |
489 | if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR)) |
490 | ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff; |
491 | else |
492 | ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff; |
493 | if (bp) |
494 | xfs_trans_brelse(args->trans, bp); |
495 | return error; |
496 | } |
497 | |
498 | /* |
499 | * Read a directory. |
500 | * |
501 | * If supplied, the transaction collects locked dir buffers to avoid |
502 | * nested buffer deadlocks. This function does not dirty the |
503 | * transaction. The caller must hold the IOLOCK (shared or exclusive) |
504 | * before calling this function. |
505 | */ |
506 | int |
507 | xfs_readdir( |
508 | struct xfs_trans *tp, |
509 | struct xfs_inode *dp, |
510 | struct dir_context *ctx, |
511 | size_t bufsize) |
512 | { |
513 | struct xfs_da_args args = { NULL }; |
514 | unsigned int lock_mode; |
515 | bool isblock; |
516 | int error; |
517 | |
518 | trace_xfs_readdir(ip: dp); |
519 | |
520 | if (xfs_is_shutdown(mp: dp->i_mount)) |
521 | return -EIO; |
522 | |
523 | ASSERT(S_ISDIR(VFS_I(dp)->i_mode)); |
524 | ASSERT(xfs_isilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL)); |
525 | XFS_STATS_INC(dp->i_mount, xs_dir_getdents); |
526 | |
527 | args.dp = dp; |
528 | args.geo = dp->i_mount->m_dir_geo; |
529 | args.trans = tp; |
530 | |
531 | if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL) |
532 | return xfs_dir2_sf_getdents(args: &args, ctx); |
533 | |
534 | lock_mode = xfs_ilock_data_map_shared(dp); |
535 | error = xfs_dir2_isblock(&args, &isblock); |
536 | if (error) |
537 | goto out_unlock; |
538 | |
539 | if (isblock) { |
540 | error = xfs_dir2_block_getdents(args: &args, ctx, lock_mode: &lock_mode); |
541 | goto out_unlock; |
542 | } |
543 | |
544 | error = xfs_dir2_leaf_getdents(args: &args, ctx, bufsize, lock_mode: &lock_mode); |
545 | |
546 | out_unlock: |
547 | if (lock_mode) |
548 | xfs_iunlock(dp, lock_mode); |
549 | return error; |
550 | } |
551 | |