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[mirror_ubuntu-artful-kernel.git] / fs / xfs / xfs_dir2_readdir.c
1 /*
2 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
3 * Copyright (c) 2013 Red Hat, Inc.
4 * All Rights Reserved.
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License as
8 * published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it would be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 */
19 #include "xfs.h"
20 #include "xfs_fs.h"
21 #include "xfs_format.h"
22 #include "xfs_log_format.h"
23 #include "xfs_trans_resv.h"
24 #include "xfs_bit.h"
25 #include "xfs_mount.h"
26 #include "xfs_da_format.h"
27 #include "xfs_da_btree.h"
28 #include "xfs_inode.h"
29 #include "xfs_dir2.h"
30 #include "xfs_dir2_priv.h"
31 #include "xfs_error.h"
32 #include "xfs_trace.h"
33 #include "xfs_bmap.h"
34 #include "xfs_trans.h"
35
36 /*
37 * Directory file type support functions
38 */
39 static unsigned char xfs_dir3_filetype_table[] = {
40 DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
41 DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
42 };
43
44 static unsigned char
45 xfs_dir3_get_dtype(
46 struct xfs_mount *mp,
47 __uint8_t filetype)
48 {
49 if (!xfs_sb_version_hasftype(&mp->m_sb))
50 return DT_UNKNOWN;
51
52 if (filetype >= XFS_DIR3_FT_MAX)
53 return DT_UNKNOWN;
54
55 return xfs_dir3_filetype_table[filetype];
56 }
57
58 STATIC int
59 xfs_dir2_sf_getdents(
60 struct xfs_da_args *args,
61 struct dir_context *ctx)
62 {
63 int i; /* shortform entry number */
64 struct xfs_inode *dp = args->dp; /* incore directory inode */
65 xfs_dir2_dataptr_t off; /* current entry's offset */
66 xfs_dir2_sf_entry_t *sfep; /* shortform directory entry */
67 xfs_dir2_sf_hdr_t *sfp; /* shortform structure */
68 xfs_dir2_dataptr_t dot_offset;
69 xfs_dir2_dataptr_t dotdot_offset;
70 xfs_ino_t ino;
71 struct xfs_da_geometry *geo = args->geo;
72
73 ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
74 ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
75 ASSERT(dp->i_df.if_u1.if_data != NULL);
76
77 sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
78
79 /*
80 * If the block number in the offset is out of range, we're done.
81 */
82 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
83 return 0;
84
85 /*
86 * Precalculate offsets for . and .. as we will always need them.
87 *
88 * XXX(hch): the second argument is sometimes 0 and sometimes
89 * geo->datablk
90 */
91 dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
92 dp->d_ops->data_dot_offset);
93 dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
94 dp->d_ops->data_dotdot_offset);
95
96 /*
97 * Put . entry unless we're starting past it.
98 */
99 if (ctx->pos <= dot_offset) {
100 ctx->pos = dot_offset & 0x7fffffff;
101 if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
102 return 0;
103 }
104
105 /*
106 * Put .. entry unless we're starting past it.
107 */
108 if (ctx->pos <= dotdot_offset) {
109 ino = dp->d_ops->sf_get_parent_ino(sfp);
110 ctx->pos = dotdot_offset & 0x7fffffff;
111 if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
112 return 0;
113 }
114
115 /*
116 * Loop while there are more entries and put'ing works.
117 */
118 sfep = xfs_dir2_sf_firstentry(sfp);
119 for (i = 0; i < sfp->count; i++) {
120 __uint8_t filetype;
121
122 off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
123 xfs_dir2_sf_get_offset(sfep));
124
125 if (ctx->pos > off) {
126 sfep = dp->d_ops->sf_nextentry(sfp, sfep);
127 continue;
128 }
129
130 ino = dp->d_ops->sf_get_ino(sfp, sfep);
131 filetype = dp->d_ops->sf_get_ftype(sfep);
132 ctx->pos = off & 0x7fffffff;
133 if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
134 xfs_dir3_get_dtype(dp->i_mount, filetype)))
135 return 0;
136 sfep = dp->d_ops->sf_nextentry(sfp, sfep);
137 }
138
139 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
140 0x7fffffff;
141 return 0;
142 }
143
144 /*
145 * Readdir for block directories.
146 */
147 STATIC int
148 xfs_dir2_block_getdents(
149 struct xfs_da_args *args,
150 struct dir_context *ctx)
151 {
152 struct xfs_inode *dp = args->dp; /* incore directory inode */
153 xfs_dir2_data_hdr_t *hdr; /* block header */
154 struct xfs_buf *bp; /* buffer for block */
155 xfs_dir2_block_tail_t *btp; /* block tail */
156 xfs_dir2_data_entry_t *dep; /* block data entry */
157 xfs_dir2_data_unused_t *dup; /* block unused entry */
158 char *endptr; /* end of the data entries */
159 int error; /* error return value */
160 char *ptr; /* current data entry */
161 int wantoff; /* starting block offset */
162 xfs_off_t cook;
163 struct xfs_da_geometry *geo = args->geo;
164 int lock_mode;
165
166 /*
167 * If the block number in the offset is out of range, we're done.
168 */
169 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
170 return 0;
171
172 lock_mode = xfs_ilock_data_map_shared(dp);
173 error = xfs_dir3_block_read(NULL, dp, &bp);
174 xfs_iunlock(dp, lock_mode);
175 if (error)
176 return error;
177
178 /*
179 * Extract the byte offset we start at from the seek pointer.
180 * We'll skip entries before this.
181 */
182 wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
183 hdr = bp->b_addr;
184 xfs_dir3_data_check(dp, bp);
185 /*
186 * Set up values for the loop.
187 */
188 btp = xfs_dir2_block_tail_p(geo, hdr);
189 ptr = (char *)dp->d_ops->data_entry_p(hdr);
190 endptr = (char *)xfs_dir2_block_leaf_p(btp);
191
192 /*
193 * Loop over the data portion of the block.
194 * Each object is a real entry (dep) or an unused one (dup).
195 */
196 while (ptr < endptr) {
197 __uint8_t filetype;
198
199 dup = (xfs_dir2_data_unused_t *)ptr;
200 /*
201 * Unused, skip it.
202 */
203 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
204 ptr += be16_to_cpu(dup->length);
205 continue;
206 }
207
208 dep = (xfs_dir2_data_entry_t *)ptr;
209
210 /*
211 * Bump pointer for the next iteration.
212 */
213 ptr += dp->d_ops->data_entsize(dep->namelen);
214 /*
215 * The entry is before the desired starting point, skip it.
216 */
217 if ((char *)dep - (char *)hdr < wantoff)
218 continue;
219
220 cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
221 (char *)dep - (char *)hdr);
222
223 ctx->pos = cook & 0x7fffffff;
224 filetype = dp->d_ops->data_get_ftype(dep);
225 /*
226 * If it didn't fit, set the final offset to here & return.
227 */
228 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
229 be64_to_cpu(dep->inumber),
230 xfs_dir3_get_dtype(dp->i_mount, filetype))) {
231 xfs_trans_brelse(NULL, bp);
232 return 0;
233 }
234 }
235
236 /*
237 * Reached the end of the block.
238 * Set the offset to a non-existent block 1 and return.
239 */
240 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
241 0x7fffffff;
242 xfs_trans_brelse(NULL, bp);
243 return 0;
244 }
245
246 struct xfs_dir2_leaf_map_info {
247 xfs_extlen_t map_blocks; /* number of fsbs in map */
248 xfs_dablk_t map_off; /* last mapped file offset */
249 int map_size; /* total entries in *map */
250 int map_valid; /* valid entries in *map */
251 int nmap; /* mappings to ask xfs_bmapi */
252 xfs_dir2_db_t curdb; /* db for current block */
253 int ra_current; /* number of read-ahead blks */
254 int ra_index; /* *map index for read-ahead */
255 int ra_offset; /* map entry offset for ra */
256 int ra_want; /* readahead count wanted */
257 struct xfs_bmbt_irec map[]; /* map vector for blocks */
258 };
259
260 STATIC int
261 xfs_dir2_leaf_readbuf(
262 struct xfs_da_args *args,
263 size_t bufsize,
264 struct xfs_dir2_leaf_map_info *mip,
265 xfs_dir2_off_t *curoff,
266 struct xfs_buf **bpp,
267 bool trim_map)
268 {
269 struct xfs_inode *dp = args->dp;
270 struct xfs_buf *bp = NULL;
271 struct xfs_bmbt_irec *map = mip->map;
272 struct blk_plug plug;
273 int error = 0;
274 int length;
275 int i;
276 int j;
277 struct xfs_da_geometry *geo = args->geo;
278
279 /*
280 * If the caller just finished processing a buffer, it will tell us
281 * we need to trim that block out of the mapping now it is done.
282 */
283 if (trim_map) {
284 mip->map_blocks -= geo->fsbcount;
285 /*
286 * Loop to get rid of the extents for the
287 * directory block.
288 */
289 for (i = geo->fsbcount; i > 0; ) {
290 j = min_t(int, map->br_blockcount, i);
291 map->br_blockcount -= j;
292 map->br_startblock += j;
293 map->br_startoff += j;
294 /*
295 * If mapping is done, pitch it from
296 * the table.
297 */
298 if (!map->br_blockcount && --mip->map_valid)
299 memmove(&map[0], &map[1],
300 sizeof(map[0]) * mip->map_valid);
301 i -= j;
302 }
303 }
304
305 /*
306 * Recalculate the readahead blocks wanted.
307 */
308 mip->ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog)) - 1;
309 ASSERT(mip->ra_want >= 0);
310
311 /*
312 * If we don't have as many as we want, and we haven't
313 * run out of data blocks, get some more mappings.
314 */
315 if (1 + mip->ra_want > mip->map_blocks &&
316 mip->map_off < xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET)) {
317 /*
318 * Get more bmaps, fill in after the ones
319 * we already have in the table.
320 */
321 mip->nmap = mip->map_size - mip->map_valid;
322 error = xfs_bmapi_read(dp, mip->map_off,
323 xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET) -
324 mip->map_off,
325 &map[mip->map_valid], &mip->nmap, 0);
326
327 /*
328 * Don't know if we should ignore this or try to return an
329 * error. The trouble with returning errors is that readdir
330 * will just stop without actually passing the error through.
331 */
332 if (error)
333 goto out; /* XXX */
334
335 /*
336 * If we got all the mappings we asked for, set the final map
337 * offset based on the last bmap value received. Otherwise,
338 * we've reached the end.
339 */
340 if (mip->nmap == mip->map_size - mip->map_valid) {
341 i = mip->map_valid + mip->nmap - 1;
342 mip->map_off = map[i].br_startoff + map[i].br_blockcount;
343 } else
344 mip->map_off = xfs_dir2_byte_to_da(geo,
345 XFS_DIR2_LEAF_OFFSET);
346
347 /*
348 * Look for holes in the mapping, and eliminate them. Count up
349 * the valid blocks.
350 */
351 for (i = mip->map_valid; i < mip->map_valid + mip->nmap; ) {
352 if (map[i].br_startblock == HOLESTARTBLOCK) {
353 mip->nmap--;
354 length = mip->map_valid + mip->nmap - i;
355 if (length)
356 memmove(&map[i], &map[i + 1],
357 sizeof(map[i]) * length);
358 } else {
359 mip->map_blocks += map[i].br_blockcount;
360 i++;
361 }
362 }
363 mip->map_valid += mip->nmap;
364 }
365
366 /*
367 * No valid mappings, so no more data blocks.
368 */
369 if (!mip->map_valid) {
370 *curoff = xfs_dir2_da_to_byte(geo, mip->map_off);
371 goto out;
372 }
373
374 /*
375 * Read the directory block starting at the first mapping.
376 */
377 mip->curdb = xfs_dir2_da_to_db(geo, map->br_startoff);
378 error = xfs_dir3_data_read(NULL, dp, map->br_startoff,
379 map->br_blockcount >= geo->fsbcount ?
380 XFS_FSB_TO_DADDR(dp->i_mount, map->br_startblock) :
381 -1, &bp);
382 /*
383 * Should just skip over the data block instead of giving up.
384 */
385 if (error)
386 goto out; /* XXX */
387
388 /*
389 * Adjust the current amount of read-ahead: we just read a block that
390 * was previously ra.
391 */
392 if (mip->ra_current)
393 mip->ra_current -= geo->fsbcount;
394
395 /*
396 * Do we need more readahead?
397 * Each loop tries to process 1 full dir blk; last may be partial.
398 */
399 blk_start_plug(&plug);
400 for (mip->ra_index = mip->ra_offset = i = 0;
401 mip->ra_want > mip->ra_current && i < mip->map_blocks;
402 i += geo->fsbcount) {
403 ASSERT(mip->ra_index < mip->map_valid);
404 /*
405 * Read-ahead a contiguous directory block.
406 */
407 if (i > mip->ra_current &&
408 (map[mip->ra_index].br_blockcount - mip->ra_offset) >=
409 geo->fsbcount) {
410 xfs_dir3_data_readahead(dp,
411 map[mip->ra_index].br_startoff + mip->ra_offset,
412 XFS_FSB_TO_DADDR(dp->i_mount,
413 map[mip->ra_index].br_startblock +
414 mip->ra_offset));
415 mip->ra_current = i;
416 }
417
418 /*
419 * Read-ahead a non-contiguous directory block. This doesn't
420 * use our mapping, but this is a very rare case.
421 */
422 else if (i > mip->ra_current) {
423 xfs_dir3_data_readahead(dp,
424 map[mip->ra_index].br_startoff +
425 mip->ra_offset, -1);
426 mip->ra_current = i;
427 }
428
429 /*
430 * Advance offset through the mapping table, processing a full
431 * dir block even if it is fragmented into several extents.
432 * But stop if we have consumed all valid mappings, even if
433 * it's not yet a full directory block.
434 */
435 for (j = 0;
436 j < geo->fsbcount && mip->ra_index < mip->map_valid;
437 j += length ) {
438 /*
439 * The rest of this extent but not more than a dir
440 * block.
441 */
442 length = min_t(int, geo->fsbcount - j,
443 map[mip->ra_index].br_blockcount -
444 mip->ra_offset);
445 mip->ra_offset += length;
446
447 /*
448 * Advance to the next mapping if this one is used up.
449 */
450 if (mip->ra_offset == map[mip->ra_index].br_blockcount) {
451 mip->ra_offset = 0;
452 mip->ra_index++;
453 }
454 }
455 }
456 blk_finish_plug(&plug);
457
458 out:
459 *bpp = bp;
460 return error;
461 }
462
463 /*
464 * Getdents (readdir) for leaf and node directories.
465 * This reads the data blocks only, so is the same for both forms.
466 */
467 STATIC int
468 xfs_dir2_leaf_getdents(
469 struct xfs_da_args *args,
470 struct dir_context *ctx,
471 size_t bufsize)
472 {
473 struct xfs_inode *dp = args->dp;
474 struct xfs_buf *bp = NULL; /* data block buffer */
475 xfs_dir2_data_hdr_t *hdr; /* data block header */
476 xfs_dir2_data_entry_t *dep; /* data entry */
477 xfs_dir2_data_unused_t *dup; /* unused entry */
478 int error = 0; /* error return value */
479 int length; /* temporary length value */
480 int byteoff; /* offset in current block */
481 xfs_dir2_off_t curoff; /* current overall offset */
482 xfs_dir2_off_t newoff; /* new curoff after new blk */
483 char *ptr = NULL; /* pointer to current data */
484 struct xfs_dir2_leaf_map_info *map_info;
485 struct xfs_da_geometry *geo = args->geo;
486
487 /*
488 * If the offset is at or past the largest allowed value,
489 * give up right away.
490 */
491 if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
492 return 0;
493
494 /*
495 * Set up to bmap a number of blocks based on the caller's
496 * buffer size, the directory block size, and the filesystem
497 * block size.
498 */
499 length = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
500 map_info = kmem_zalloc(offsetof(struct xfs_dir2_leaf_map_info, map) +
501 (length * sizeof(struct xfs_bmbt_irec)),
502 KM_SLEEP | KM_NOFS);
503 map_info->map_size = length;
504
505 /*
506 * Inside the loop we keep the main offset value as a byte offset
507 * in the directory file.
508 */
509 curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
510
511 /*
512 * Force this conversion through db so we truncate the offset
513 * down to get the start of the data block.
514 */
515 map_info->map_off = xfs_dir2_db_to_da(geo,
516 xfs_dir2_byte_to_db(geo, curoff));
517
518 /*
519 * Loop over directory entries until we reach the end offset.
520 * Get more blocks and readahead as necessary.
521 */
522 while (curoff < XFS_DIR2_LEAF_OFFSET) {
523 __uint8_t filetype;
524
525 /*
526 * If we have no buffer, or we're off the end of the
527 * current buffer, need to get another one.
528 */
529 if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {
530 int lock_mode;
531 bool trim_map = false;
532
533 if (bp) {
534 xfs_trans_brelse(NULL, bp);
535 bp = NULL;
536 trim_map = true;
537 }
538
539 lock_mode = xfs_ilock_data_map_shared(dp);
540 error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
541 &curoff, &bp, trim_map);
542 xfs_iunlock(dp, lock_mode);
543 if (error || !map_info->map_valid)
544 break;
545
546 /*
547 * Having done a read, we need to set a new offset.
548 */
549 newoff = xfs_dir2_db_off_to_byte(geo,
550 map_info->curdb, 0);
551 /*
552 * Start of the current block.
553 */
554 if (curoff < newoff)
555 curoff = newoff;
556 /*
557 * Make sure we're in the right block.
558 */
559 else if (curoff > newoff)
560 ASSERT(xfs_dir2_byte_to_db(geo, curoff) ==
561 map_info->curdb);
562 hdr = bp->b_addr;
563 xfs_dir3_data_check(dp, bp);
564 /*
565 * Find our position in the block.
566 */
567 ptr = (char *)dp->d_ops->data_entry_p(hdr);
568 byteoff = xfs_dir2_byte_to_off(geo, curoff);
569 /*
570 * Skip past the header.
571 */
572 if (byteoff == 0)
573 curoff += dp->d_ops->data_entry_offset;
574 /*
575 * Skip past entries until we reach our offset.
576 */
577 else {
578 while ((char *)ptr - (char *)hdr < byteoff) {
579 dup = (xfs_dir2_data_unused_t *)ptr;
580
581 if (be16_to_cpu(dup->freetag)
582 == XFS_DIR2_DATA_FREE_TAG) {
583
584 length = be16_to_cpu(dup->length);
585 ptr += length;
586 continue;
587 }
588 dep = (xfs_dir2_data_entry_t *)ptr;
589 length =
590 dp->d_ops->data_entsize(dep->namelen);
591 ptr += length;
592 }
593 /*
594 * Now set our real offset.
595 */
596 curoff =
597 xfs_dir2_db_off_to_byte(geo,
598 xfs_dir2_byte_to_db(geo, curoff),
599 (char *)ptr - (char *)hdr);
600 if (ptr >= (char *)hdr + geo->blksize) {
601 continue;
602 }
603 }
604 }
605 /*
606 * We have a pointer to an entry.
607 * Is it a live one?
608 */
609 dup = (xfs_dir2_data_unused_t *)ptr;
610 /*
611 * No, it's unused, skip over it.
612 */
613 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
614 length = be16_to_cpu(dup->length);
615 ptr += length;
616 curoff += length;
617 continue;
618 }
619
620 dep = (xfs_dir2_data_entry_t *)ptr;
621 length = dp->d_ops->data_entsize(dep->namelen);
622 filetype = dp->d_ops->data_get_ftype(dep);
623
624 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
625 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
626 be64_to_cpu(dep->inumber),
627 xfs_dir3_get_dtype(dp->i_mount, filetype)))
628 break;
629
630 /*
631 * Advance to next entry in the block.
632 */
633 ptr += length;
634 curoff += length;
635 /* bufsize may have just been a guess; don't go negative */
636 bufsize = bufsize > length ? bufsize - length : 0;
637 }
638
639 /*
640 * All done. Set output offset value to current offset.
641 */
642 if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
643 ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
644 else
645 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
646 kmem_free(map_info);
647 if (bp)
648 xfs_trans_brelse(NULL, bp);
649 return error;
650 }
651
652 /*
653 * Read a directory.
654 */
655 int
656 xfs_readdir(
657 struct xfs_inode *dp,
658 struct dir_context *ctx,
659 size_t bufsize)
660 {
661 struct xfs_da_args args = { NULL };
662 int rval;
663 int v;
664
665 trace_xfs_readdir(dp);
666
667 if (XFS_FORCED_SHUTDOWN(dp->i_mount))
668 return -EIO;
669
670 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
671 XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
672
673 args.dp = dp;
674 args.geo = dp->i_mount->m_dir_geo;
675
676 if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
677 rval = xfs_dir2_sf_getdents(&args, ctx);
678 else if ((rval = xfs_dir2_isblock(&args, &v)))
679 ;
680 else if (v)
681 rval = xfs_dir2_block_getdents(&args, ctx);
682 else
683 rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
684
685 return rval;
686 }