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
21 /*
22 * Directory file type support functions
23 */
24 static unsigned char xfs_dir3_filetype_table[] = {
25 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
26 DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
27 };
28
29 unsigned char
30 xfs_dir3_get_dtype(
31 struct xfs_mount *mp,
32 uint8_t filetype)
33 {
34 if (!xfs_sb_version_hasftype(&mp->m_sb))
35 return DT_UNKNOWN;
36
37 if (filetype >= XFS_DIR3_FT_MAX)
38 return DT_UNKNOWN;
39
40 return xfs_dir3_filetype_table[filetype];
41 }
42
43 STATIC int
44 xfs_dir2_sf_getdents(
45 struct xfs_da_args *args,
46 struct dir_context *ctx)
47 {
48 int i; /* shortform entry number */
49 struct xfs_inode *dp = args->dp; /* incore directory inode */
50 xfs_dir2_dataptr_t off; /* current entry's offset */
51 xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
52 xfs_dir2_sf_hdr_t *sfp; /* shortform structure */
53 xfs_dir2_dataptr_t dot_offset;
54 xfs_dir2_dataptr_t dotdot_offset;
55 xfs_ino_t ino;
56 struct xfs_da_geometry *geo = args->geo;
57
58 ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
59 ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
60 ASSERT(dp->i_df.if_u1.if_data != NULL);
61
62 sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
63
64 /*
65 * If the block number in the offset is out of range, we're done.
66 */
67 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
68 return 0;
69
70 /*
71 * Precalculate offsets for . and .. as we will always need them.
72 *
73 * XXX(hch): the second argument is sometimes 0 and sometimes
74 * geo->datablk
75 */
76 dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
77 dp->d_ops->data_dot_offset);
78 dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
79 dp->d_ops->data_dotdot_offset);
80
81 /*
82 * Put . entry unless we're starting past it.
83 */
84 if (ctx->pos <= dot_offset) {
85 ctx->pos = dot_offset & 0x7fffffff;
86 if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
87 return 0;
88 }
89
90 /*
91 * Put .. entry unless we're starting past it.
92 */
93 if (ctx->pos <= dotdot_offset) {
94 ino = dp->d_ops->sf_get_parent_ino(sfp);
95 ctx->pos = dotdot_offset & 0x7fffffff;
96 if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
97 return 0;
98 }
99
100 /*
101 * Loop while there are more entries and put'ing works.
102 */
103 sfep = xfs_dir2_sf_firstentry(sfp);
104 for (i = 0; i < sfp->count; i++) {
105 uint8_t filetype;
106
107 off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
108 xfs_dir2_sf_get_offset(sfep));
109
110 if (ctx->pos > off) {
111 sfep = dp->d_ops->sf_nextentry(sfp, sfep);
112 continue;
113 }
114
115 ino = dp->d_ops->sf_get_ino(sfp, sfep);
116 filetype = dp->d_ops->sf_get_ftype(sfep);
117 ctx->pos = off & 0x7fffffff;
118 if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
119 xfs_dir3_get_dtype(dp->i_mount, filetype)))
120 return 0;
121 sfep = dp->d_ops->sf_nextentry(sfp, sfep);
122 }
123
124 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
125 0x7fffffff;
126 return 0;
127 }
128
129 /*
130 * Readdir for block directories.
131 */
132 STATIC int
133 xfs_dir2_block_getdents(
134 struct xfs_da_args *args,
135 struct dir_context *ctx)
136 {
137 struct xfs_inode *dp = args->dp; /* incore directory inode */
138 xfs_dir2_data_hdr_t *hdr; /* block header */
139 struct xfs_buf *bp; /* buffer for block */
140 xfs_dir2_data_entry_t *dep; /* block data entry */
141 xfs_dir2_data_unused_t *dup; /* block unused entry */
142 char *endptr; /* end of the data entries */
143 int error; /* error return value */
144 char *ptr; /* current data entry */
145 int wantoff; /* starting block offset */
146 xfs_off_t cook;
147 struct xfs_da_geometry *geo = args->geo;
148 int lock_mode;
149
150 /*
151 * If the block number in the offset is out of range, we're done.
152 */
153 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
154 return 0;
155
156 lock_mode = xfs_ilock_data_map_shared(dp);
157 error = xfs_dir3_block_read(args->trans, dp, &bp);
158 xfs_iunlock(dp, lock_mode);
159 if (error)
160 return error;
161
162 /*
163 * Extract the byte offset we start at from the seek pointer.
164 * We'll skip entries before this.
165 */
166 wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
167 hdr = bp->b_addr;
168 xfs_dir3_data_check(dp, bp);
169 /*
170 * Set up values for the loop.
171 */
172 ptr = (char *)dp->d_ops->data_entry_p(hdr);
173 endptr = xfs_dir3_data_endp(geo, hdr);
174
175 /*
176 * Loop over the data portion of the block.
177 * Each object is a real entry (dep) or an unused one (dup).
178 */
179 while (ptr < endptr) {
180 uint8_t filetype;
181
182 dup = (xfs_dir2_data_unused_t *)ptr;
183 /*
184 * Unused, skip it.
185 */
186 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
187 ptr += be16_to_cpu(dup->length);
188 continue;
189 }
190
191 dep = (xfs_dir2_data_entry_t *)ptr;
192
193 /*
194 * Bump pointer for the next iteration.
195 */
196 ptr += dp->d_ops->data_entsize(dep->namelen);
197 /*
198 * The entry is before the desired starting point, skip it.
199 */
200 if ((char *)dep - (char *)hdr < wantoff)
201 continue;
202
203 cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
204 (char *)dep - (char *)hdr);
205
206 ctx->pos = cook & 0x7fffffff;
207 filetype = dp->d_ops->data_get_ftype(dep);
208 /*
209 * If it didn't fit, set the final offset to here & return.
210 */
211 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
212 be64_to_cpu(dep->inumber),
213 xfs_dir3_get_dtype(dp->i_mount, filetype))) {
214 xfs_trans_brelse(args->trans, bp);
215 return 0;
216 }
217 }
218
219 /*
220 * Reached the end of the block.
221 * Set the offset to a non-existent block 1 and return.
222 */
223 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
224 0x7fffffff;
225 xfs_trans_brelse(args->trans, bp);
226 return 0;
227 }
228
229 /*
230 * Read a directory block and initiate readahead for blocks beyond that.
231 * We maintain a sliding readahead window of the remaining space in the
232 * buffer rounded up to the nearest block.
233 */
234 STATIC int
235 xfs_dir2_leaf_readbuf(
236 struct xfs_da_args *args,
237 size_t bufsize,
238 xfs_dir2_off_t *cur_off,
239 xfs_dablk_t *ra_blk,
240 struct xfs_buf **bpp)
241 {
242 struct xfs_inode *dp = args->dp;
243 struct xfs_buf *bp = NULL;
244 struct xfs_da_geometry *geo = args->geo;
245 struct xfs_ifork *ifp = XFS_IFORK_PTR(dp, XFS_DATA_FORK);
246 struct xfs_bmbt_irec map;
247 struct blk_plug plug;
248 xfs_dir2_off_t new_off;
249 xfs_dablk_t next_ra;
250 xfs_dablk_t map_off;
251 xfs_dablk_t last_da;
252 struct xfs_iext_cursor icur;
253 int ra_want;
254 int error = 0;
255
256 if (!(ifp->if_flags & XFS_IFEXTENTS)) {
257 error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
258 if (error)
259 goto out;
260 }
261
262 /*
263 * Look for mapped directory blocks at or above the current offset.
264 * Truncate down to the nearest directory block to start the scanning
265 * operation.
266 */
267 last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
268 map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
269 if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
270 goto out;
271 if (map.br_startoff >= last_da)
272 goto out;
273 xfs_trim_extent(&map, map_off, last_da - map_off);
274
275 /* Read the directory block of that first mapping. */
276 new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
277 if (new_off > *cur_off)
278 *cur_off = new_off;
279 error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, -1, &bp);
280 if (error)
281 goto out;
282
283 /*
284 * Start readahead for the next bufsize's worth of dir data blocks.
285 * We may have already issued readahead for some of that range;
286 * ra_blk tracks the last block we tried to read(ahead).
287 */
288 ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
289 if (*ra_blk >= last_da)
290 goto out;
291 else if (*ra_blk == 0)
292 *ra_blk = map.br_startoff;
293 next_ra = map.br_startoff + geo->fsbcount;
294 if (next_ra >= last_da)
295 goto out_no_ra;
296 if (map.br_blockcount < geo->fsbcount &&
297 !xfs_iext_next_extent(ifp, &icur, &map))
298 goto out_no_ra;
299 if (map.br_startoff >= last_da)
300 goto out_no_ra;
301 xfs_trim_extent(&map, next_ra, last_da - next_ra);
302
303 /* Start ra for each dir (not fs) block that has a mapping. */
304 blk_start_plug(&plug);
305 while (ra_want > 0) {
306 next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
307 while (ra_want > 0 &&
308 next_ra < map.br_startoff + map.br_blockcount) {
309 if (next_ra >= last_da) {
310 *ra_blk = last_da;
311 break;
312 }
313 if (next_ra > *ra_blk) {
314 xfs_dir3_data_readahead(dp, next_ra, -2);
315 *ra_blk = next_ra;
316 }
317 ra_want -= geo->fsbcount;
318 next_ra += geo->fsbcount;
319 }
320 if (!xfs_iext_next_extent(ifp, &icur, &map)) {
321 *ra_blk = last_da;
322 break;
323 }
324 }
325 blk_finish_plug(&plug);
326
327 out:
328 *bpp = bp;
329 return error;
330 out_no_ra:
331 *ra_blk = last_da;
332 goto out;
333 }
334
335 /*
336 * Getdents (readdir) for leaf and node directories.
337 * This reads the data blocks only, so is the same for both forms.
338 */
339 STATIC int
340 xfs_dir2_leaf_getdents(
341 struct xfs_da_args *args,
342 struct dir_context *ctx,
343 size_t bufsize)
344 {
345 struct xfs_inode *dp = args->dp;
346 struct xfs_buf *bp = NULL; /* data block buffer */
347 xfs_dir2_data_hdr_t *hdr; /* data block header */
348 xfs_dir2_data_entry_t *dep; /* data entry */
349 xfs_dir2_data_unused_t *dup; /* unused entry */
350 char *ptr = NULL; /* pointer to current data */
351 struct xfs_da_geometry *geo = args->geo;
352 xfs_dablk_t rablk = 0; /* current readahead block */
353 xfs_dir2_off_t curoff; /* current overall offset */
354 int length; /* temporary length value */
355 int byteoff; /* offset in current block */
356 int lock_mode;
357 int error = 0; /* error return value */
358
359 /*
360 * If the offset is at or past the largest allowed value,
361 * give up right away.
362 */
363 if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
364 return 0;
365
366 /*
367 * Inside the loop we keep the main offset value as a byte offset
368 * in the directory file.
369 */
370 curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
371
372 /*
373 * Loop over directory entries until we reach the end offset.
374 * Get more blocks and readahead as necessary.
375 */
376 while (curoff < XFS_DIR2_LEAF_OFFSET) {
377 uint8_t filetype;
378
379 /*
380 * If we have no buffer, or we're off the end of the
381 * current buffer, need to get another one.
382 */
383 if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {
384 if (bp) {
385 xfs_trans_brelse(args->trans, bp);
386 bp = NULL;
387 }
388
389 lock_mode = xfs_ilock_data_map_shared(dp);
390 error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
391 &rablk, &bp);
392 xfs_iunlock(dp, lock_mode);
393 if (error || !bp)
394 break;
395
396 hdr = bp->b_addr;
397 xfs_dir3_data_check(dp, bp);
398 /*
399 * Find our position in the block.
400 */
401 ptr = (char *)dp->d_ops->data_entry_p(hdr);
402 byteoff = xfs_dir2_byte_to_off(geo, curoff);
403 /*
404 * Skip past the header.
405 */
406 if (byteoff == 0)
407 curoff += dp->d_ops->data_entry_offset;
408 /*
409 * Skip past entries until we reach our offset.
410 */
411 else {
412 while ((char *)ptr - (char *)hdr < byteoff) {
413 dup = (xfs_dir2_data_unused_t *)ptr;
414
415 if (be16_to_cpu(dup->freetag)
416 == XFS_DIR2_DATA_FREE_TAG) {
417
418 length = be16_to_cpu(dup->length);
419 ptr += length;
420 continue;
421 }
422 dep = (xfs_dir2_data_entry_t *)ptr;
423 length =
424 dp->d_ops->data_entsize(dep->namelen);
425 ptr += length;
426 }
427 /*
428 * Now set our real offset.
429 */
430 curoff =
431 xfs_dir2_db_off_to_byte(geo,
432 xfs_dir2_byte_to_db(geo, curoff),
433 (char *)ptr - (char *)hdr);
434 if (ptr >= (char *)hdr + geo->blksize) {
435 continue;
436 }
437 }
438 }
439 /*
440 * We have a pointer to an entry.
441 * Is it a live one?
442 */
443 dup = (xfs_dir2_data_unused_t *)ptr;
444 /*
445 * No, it's unused, skip over it.
446 */
447 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
448 length = be16_to_cpu(dup->length);
449 ptr += length;
450 curoff += length;
451 continue;
452 }
453
454 dep = (xfs_dir2_data_entry_t *)ptr;
455 length = dp->d_ops->data_entsize(dep->namelen);
456 filetype = dp->d_ops->data_get_ftype(dep);
457
458 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
459 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
460 be64_to_cpu(dep->inumber),
461 xfs_dir3_get_dtype(dp->i_mount, filetype)))
462 break;
463
464 /*
465 * Advance to next entry in the block.
466 */
467 ptr += length;
468 curoff += length;
469 /* bufsize may have just been a guess; don't go negative */
470 bufsize = bufsize > length ? bufsize - length : 0;
471 }
472
473 /*
474 * All done. Set output offset value to current offset.
475 */
476 if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
477 ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
478 else
479 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
480 if (bp)
481 xfs_trans_brelse(args->trans, bp);
482 return error;
483 }
484
485 /*
486 * Read a directory.
487 *
488 * If supplied, the transaction collects locked dir buffers to avoid
489 * nested buffer deadlocks. This function does not dirty the
490 * transaction. The caller should ensure that the inode is locked
491 * before calling this function.
492 */
493 int
494 xfs_readdir(
495 struct xfs_trans *tp,
496 struct xfs_inode *dp,
497 struct dir_context *ctx,
498 size_t bufsize)
499 {
500 struct xfs_da_args args = { NULL };
501 int rval;
502 int v;
503
504 trace_xfs_readdir(dp);
505
506 if (XFS_FORCED_SHUTDOWN(dp->i_mount))
507 return -EIO;
508
509 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
510 XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
511
512 args.dp = dp;
513 args.geo = dp->i_mount->m_dir_geo;
514 args.trans = tp;
515
516 if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
517 rval = xfs_dir2_sf_getdents(&args, ctx);
518 else if ((rval = xfs_dir2_isblock(&args, &v)))
519 ;
520 else if (v)
521 rval = xfs_dir2_block_getdents(&args, ctx);
522 else
523 rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
524
525 return rval;
526 }