summaryrefslogtreecommitdiffstats
path: root/fs/xfs/xfs_dir2_readdir.c
blob: b5a10d2e9aefa813ebc66900d665772b292b2cef (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_bit.h"
#include "xfs_mount.h"
#include "xfs_da_format.h"
#include "xfs_da_btree.h"
#include "xfs_inode.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_error.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_trans.h"

/*
 * Directory file type support functions
 */
static unsigned char xfs_dir3_filetype_table[] = {
	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
	DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
};

unsigned char
xfs_dir3_get_dtype(
	struct xfs_mount	*mp,
	__uint8_t		filetype)
{
	if (!xfs_sb_version_hasftype(&mp->m_sb))
		return DT_UNKNOWN;

	if (filetype >= XFS_DIR3_FT_MAX)
		return DT_UNKNOWN;

	return xfs_dir3_filetype_table[filetype];
}
/*
 * @mode, if set, indicates that the type field needs to be set up.
 * This uses the transformation from file mode to DT_* as defined in linux/fs.h
 * for file type specification. This will be propagated into the directory
 * structure if appropriate for the given operation and filesystem config.
 */
const unsigned char xfs_mode_to_ftype[S_IFMT >> S_SHIFT] = {
	[0]			= XFS_DIR3_FT_UNKNOWN,
	[S_IFREG >> S_SHIFT]    = XFS_DIR3_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT]    = XFS_DIR3_FT_DIR,
	[S_IFCHR >> S_SHIFT]    = XFS_DIR3_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT]    = XFS_DIR3_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT]    = XFS_DIR3_FT_FIFO,
	[S_IFSOCK >> S_SHIFT]   = XFS_DIR3_FT_SOCK,
	[S_IFLNK >> S_SHIFT]    = XFS_DIR3_FT_SYMLINK,
};

STATIC int
xfs_dir2_sf_getdents(
	struct xfs_da_args	*args,
	struct dir_context	*ctx)
{
	int			i;		/* shortform entry number */
	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
	xfs_dir2_dataptr_t	off;		/* current entry's offset */
	xfs_dir2_sf_entry_t	*sfep;		/* shortform directory entry */
	xfs_dir2_sf_hdr_t	*sfp;		/* shortform structure */
	xfs_dir2_dataptr_t	dot_offset;
	xfs_dir2_dataptr_t	dotdot_offset;
	xfs_ino_t		ino;
	struct xfs_da_geometry	*geo = args->geo;

	ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
	/*
	 * Give up if the directory is way too short.
	 */
	if (dp->i_d.di_size < offsetof(xfs_dir2_sf_hdr_t, parent)) {
		ASSERT(XFS_FORCED_SHUTDOWN(dp->i_mount));
		return -EIO;
	}

	ASSERT(dp->i_df.if_bytes == dp->i_d.di_size);
	ASSERT(dp->i_df.if_u1.if_data != NULL);

	sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;

	ASSERT(dp->i_d.di_size >= xfs_dir2_sf_hdr_size(sfp->i8count));

	/*
	 * If the block number in the offset is out of range, we're done.
	 */
	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
		return 0;

	/*
	 * Precalculate offsets for . and .. as we will always need them.
	 *
	 * XXX(hch): the second argument is sometimes 0 and sometimes
	 * geo->datablk
	 */
	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
						dp->d_ops->data_dot_offset);
	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
						dp->d_ops->data_dotdot_offset);

	/*
	 * Put . entry unless we're starting past it.
	 */
	if (ctx->pos <= dot_offset) {
		ctx->pos = dot_offset & 0x7fffffff;
		if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
			return 0;
	}

	/*
	 * Put .. entry unless we're starting past it.
	 */
	if (ctx->pos <= dotdot_offset) {
		ino = dp->d_ops->sf_get_parent_ino(sfp);
		ctx->pos = dotdot_offset & 0x7fffffff;
		if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
			return 0;
	}

	/*
	 * Loop while there are more entries and put'ing works.
	 */
	sfep = xfs_dir2_sf_firstentry(sfp);
	for (i = 0; i < sfp->count; i++) {
		__uint8_t filetype;

		off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
				xfs_dir2_sf_get_offset(sfep));

		if (ctx->pos > off) {
			sfep = dp->d_ops->sf_nextentry(sfp, sfep);
			continue;
		}

		ino = dp->d_ops->sf_get_ino(sfp, sfep);
		filetype = dp->d_ops->sf_get_ftype(sfep);
		ctx->pos = off & 0x7fffffff;
		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
			return 0;
		sfep = dp->d_ops->sf_nextentry(sfp, sfep);
	}

	ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
								0x7fffffff;
	return 0;
}

/*
 * Readdir for block directories.
 */
STATIC int
xfs_dir2_block_getdents(
	struct xfs_da_args	*args,
	struct dir_context	*ctx)
{
	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
	xfs_dir2_data_hdr_t	*hdr;		/* block header */
	struct xfs_buf		*bp;		/* buffer for block */
	xfs_dir2_block_tail_t	*btp;		/* block tail */
	xfs_dir2_data_entry_t	*dep;		/* block data entry */
	xfs_dir2_data_unused_t	*dup;		/* block unused entry */
	char			*endptr;	/* end of the data entries */
	int			error;		/* error return value */
	char			*ptr;		/* current data entry */
	int			wantoff;	/* starting block offset */
	xfs_off_t		cook;
	struct xfs_da_geometry	*geo = args->geo;

	/*
	 * If the block number in the offset is out of range, we're done.
	 */
	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
		return 0;

	error = xfs_dir3_block_read(NULL, dp, &bp);
	if (error)
		return error;

	/*
	 * Extract the byte offset we start at from the seek pointer.
	 * We'll skip entries before this.
	 */
	wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
	hdr = bp->b_addr;
	xfs_dir3_data_check(dp, bp);
	/*
	 * Set up values for the loop.
	 */
	btp = xfs_dir2_block_tail_p(geo, hdr);
	ptr = (char *)dp->d_ops->data_entry_p(hdr);
	endptr = (char *)xfs_dir2_block_leaf_p(btp);

	/*
	 * Loop over the data portion of the block.
	 * Each object is a real entry (dep) or an unused one (dup).
	 */
	while (ptr < endptr) {
		__uint8_t filetype;

		dup = (xfs_dir2_data_unused_t *)ptr;
		/*
		 * Unused, skip it.
		 */
		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
			ptr += be16_to_cpu(dup->length);
			continue;
		}

		dep = (xfs_dir2_data_entry_t *)ptr;

		/*
		 * Bump pointer for the next iteration.
		 */
		ptr += dp->d_ops->data_entsize(dep->namelen);
		/*
		 * The entry is before the desired starting point, skip it.
		 */
		if ((char *)dep - (char *)hdr < wantoff)
			continue;

		cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
					    (char *)dep - (char *)hdr);

		ctx->pos = cook & 0x7fffffff;
		filetype = dp->d_ops->data_get_ftype(dep);
		/*
		 * If it didn't fit, set the final offset to here & return.
		 */
		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
			    be64_to_cpu(dep->inumber),
			    xfs_dir3_get_dtype(dp->i_mount, filetype))) {
			xfs_trans_brelse(NULL, bp);
			return 0;
		}
	}

	/*
	 * Reached the end of the block.
	 * Set the offset to a non-existent block 1 and return.
	 */
	ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
								0x7fffffff;
	xfs_trans_brelse(NULL, bp);
	return 0;
}

struct xfs_dir2_leaf_map_info {
	xfs_extlen_t	map_blocks;	/* number of fsbs in map */
	xfs_dablk_t	map_off;	/* last mapped file offset */
	int		map_size;	/* total entries in *map */
	int		map_valid;	/* valid entries in *map */
	int		nmap;		/* mappings to ask xfs_bmapi */
	xfs_dir2_db_t	curdb;		/* db for current block */
	int		ra_current;	/* number of read-ahead blks */
	int		ra_index;	/* *map index for read-ahead */
	int		ra_offset;	/* map entry offset for ra */
	int		ra_want;	/* readahead count wanted */
	struct xfs_bmbt_irec map[];	/* map vector for blocks */
};

STATIC int
xfs_dir2_leaf_readbuf(
	struct xfs_da_args	*args,
	size_t			bufsize,
	struct xfs_dir2_leaf_map_info *mip,
	xfs_dir2_off_t		*curoff,
	struct xfs_buf		**bpp)
{
	struct xfs_inode	*dp = args->dp;
	struct xfs_buf		*bp = *bpp;
	struct xfs_bmbt_irec	*map = mip->map;
	struct blk_plug		plug;
	int			error = 0;
	int			length;
	int			i;
	int			j;
	struct xfs_da_geometry	*geo = args->geo;

	/*
	 * If we have a buffer, we need to release it and
	 * take it out of the mapping.
	 */

	if (bp) {
		xfs_trans_brelse(NULL, bp);
		bp = NULL;
		mip->map_blocks -= geo->fsbcount;
		/*
		 * Loop to get rid of the extents for the
		 * directory block.
		 */
		for (i = geo->fsbcount; i > 0; ) {
			j = min_t(int, map->br_blockcount, i);
			map->br_blockcount -= j;
			map->br_startblock += j;
			map->br_startoff += j;
			/*
			 * If mapping is done, pitch it from
			 * the table.
			 */
			if (!map->br_blockcount && --mip->map_valid)
				memmove(&map[0], &map[1],
					sizeof(map[0]) * mip->map_valid);
			i -= j;
		}
	}

	/*
	 * Recalculate the readahead blocks wanted.
	 */
	mip->ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog)) - 1;
	ASSERT(mip->ra_want >= 0);

	/*
	 * If we don't have as many as we want, and we haven't
	 * run out of data blocks, get some more mappings.
	 */
	if (1 + mip->ra_want > mip->map_blocks &&
	    mip->map_off < xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET)) {
		/*
		 * Get more bmaps, fill in after the ones
		 * we already have in the table.
		 */
		mip->nmap = mip->map_size - mip->map_valid;
		error = xfs_bmapi_read(dp, mip->map_off,
				xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET) -
								mip->map_off,
				&map[mip->map_valid], &mip->nmap, 0);

		/*
		 * Don't know if we should ignore this or try to return an
		 * error.  The trouble with returning errors is that readdir
		 * will just stop without actually passing the error through.
		 */
		if (error)
			goto out;	/* XXX */

		/*
		 * If we got all the mappings we asked for, set the final map
		 * offset based on the last bmap value received.  Otherwise,
		 * we've reached the end.
		 */
		if (mip->nmap == mip->map_size - mip->map_valid) {
			i = mip->map_valid + mip->nmap - 1;
			mip->map_off = map[i].br_startoff + map[i].br_blockcount;
		} else
			mip->map_off = xfs_dir2_byte_to_da(geo,
							XFS_DIR2_LEAF_OFFSET);

		/*
		 * Look for holes in the mapping, and eliminate them.  Count up
		 * the valid blocks.
		 */
		for (i = mip->map_valid; i < mip->map_valid + mip->nmap; ) {
			if (map[i].br_startblock == HOLESTARTBLOCK) {
				mip->nmap--;
				length = mip->map_valid + mip->nmap - i;
				if (length)
					memmove(&map[i], &map[i + 1],
						sizeof(map[i]) * length);
			} else {
				mip->map_blocks += map[i].br_blockcount;
				i++;
			}
		}
		mip->map_valid += mip->nmap;
	}

	/*
	 * No valid mappings, so no more data blocks.
	 */
	if (!mip->map_valid) {
		*curoff = xfs_dir2_da_to_byte(geo, mip->map_off);
		goto out;
	}

	/*
	 * Read the directory block starting at the first mapping.
	 */
	mip->curdb = xfs_dir2_da_to_db(geo, map->br_startoff);
	error = xfs_dir3_data_read(NULL, dp, map->br_startoff,
			map->br_blockcount >= geo->fsbcount ?
			    XFS_FSB_TO_DADDR(dp->i_mount, map->br_startblock) :
			    -1, &bp);
	/*
	 * Should just skip over the data block instead of giving up.
	 */
	if (error)
		goto out;	/* XXX */

	/*
	 * Adjust the current amount of read-ahead: we just read a block that
	 * was previously ra.
	 */
	if (mip->ra_current)
		mip->ra_current -= geo->fsbcount;

	/*
	 * Do we need more readahead?
	 */
	blk_start_plug(&plug);
	for (mip->ra_index = mip->ra_offset = i = 0;
	     mip->ra_want > mip->ra_current && i < mip->map_blocks;
	     i += geo->fsbcount) {
		ASSERT(mip->ra_index < mip->map_valid);
		/*
		 * Read-ahead a contiguous directory block.
		 */
		if (i > mip->ra_current &&
		    map[mip->ra_index].br_blockcount >= geo->fsbcount) {
			xfs_dir3_data_readahead(dp,
				map[mip->ra_index].br_startoff + mip->ra_offset,
				XFS_FSB_TO_DADDR(dp->i_mount,
					map[mip->ra_index].br_startblock +
							mip->ra_offset));
			mip->ra_current = i;
		}

		/*
		 * Read-ahead a non-contiguous directory block.  This doesn't
		 * use our mapping, but this is a very rare case.
		 */
		else if (i > mip->ra_current) {
			xfs_dir3_data_readahead(dp,
					map[mip->ra_index].br_startoff +
							mip->ra_offset, -1);
			mip->ra_current = i;
		}

		/*
		 * Advance offset through the mapping table.
		 */
		for (j = 0; j < geo->fsbcount; j += length ) {
			/*
			 * The rest of this extent but not more than a dir
			 * block.
			 */
			length = min_t(int, geo->fsbcount,
					map[mip->ra_index].br_blockcount -
							mip->ra_offset);
			mip->ra_offset += length;

			/*
			 * Advance to the next mapping if this one is used up.
			 */
			if (mip->ra_offset == map[mip->ra_index].br_blockcount) {
				mip->ra_offset = 0;
				mip->ra_index++;
			}
		}
	}
	blk_finish_plug(&plug);

out:
	*bpp = bp;
	return error;
}

/*
 * Getdents (readdir) for leaf and node directories.
 * This reads the data blocks only, so is the same for both forms.
 */
STATIC int
xfs_dir2_leaf_getdents(
	struct xfs_da_args	*args,
	struct dir_context	*ctx,
	size_t			bufsize)
{
	struct xfs_inode	*dp = args->dp;
	struct xfs_buf		*bp = NULL;	/* data block buffer */
	xfs_dir2_data_hdr_t	*hdr;		/* data block header */
	xfs_dir2_data_entry_t	*dep;		/* data entry */
	xfs_dir2_data_unused_t	*dup;		/* unused entry */
	int			error = 0;	/* error return value */
	int			length;		/* temporary length value */
	int			byteoff;	/* offset in current block */
	xfs_dir2_off_t		curoff;		/* current overall offset */
	xfs_dir2_off_t		newoff;		/* new curoff after new blk */
	char			*ptr = NULL;	/* pointer to current data */
	struct xfs_dir2_leaf_map_info *map_info;
	struct xfs_da_geometry	*geo = args->geo;

	/*
	 * If the offset is at or past the largest allowed value,
	 * give up right away.
	 */
	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
		return 0;

	/*
	 * Set up to bmap a number of blocks based on the caller's
	 * buffer size, the directory block size, and the filesystem
	 * block size.
	 */
	length = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
	map_info = kmem_zalloc(offsetof(struct xfs_dir2_leaf_map_info, map) +
				(length * sizeof(struct xfs_bmbt_irec)),
			       KM_SLEEP | KM_NOFS);
	map_info->map_size = length;

	/*
	 * Inside the loop we keep the main offset value as a byte offset
	 * in the directory file.
	 */
	curoff = xfs_dir2_dataptr_to_byte(ctx->pos);

	/*
	 * Force this conversion through db so we truncate the offset
	 * down to get the start of the data block.
	 */
	map_info->map_off = xfs_dir2_db_to_da(geo,
					      xfs_dir2_byte_to_db(geo, curoff));

	/*
	 * Loop over directory entries until we reach the end offset.
	 * Get more blocks and readahead as necessary.
	 */
	while (curoff < XFS_DIR2_LEAF_OFFSET) {
		__uint8_t filetype;

		/*
		 * If we have no buffer, or we're off the end of the
		 * current buffer, need to get another one.
		 */
		if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {

			error = xfs_dir2_leaf_readbuf(args, bufsize, map_info,
						      &curoff, &bp);
			if (error || !map_info->map_valid)
				break;

			/*
			 * Having done a read, we need to set a new offset.
			 */
			newoff = xfs_dir2_db_off_to_byte(geo,
							 map_info->curdb, 0);
			/*
			 * Start of the current block.
			 */
			if (curoff < newoff)
				curoff = newoff;
			/*
			 * Make sure we're in the right block.
			 */
			else if (curoff > newoff)
				ASSERT(xfs_dir2_byte_to_db(geo, curoff) ==
				       map_info->curdb);
			hdr = bp->b_addr;
			xfs_dir3_data_check(dp, bp);
			/*
			 * Find our position in the block.
			 */
			ptr = (char *)dp->d_ops->data_entry_p(hdr);
			byteoff = xfs_dir2_byte_to_off(geo, curoff);
			/*
			 * Skip past the header.
			 */
			if (byteoff == 0)
				curoff += dp->d_ops->data_entry_offset;
			/*
			 * Skip past entries until we reach our offset.
			 */
			else {
				while ((char *)ptr - (char *)hdr < byteoff) {
					dup = (xfs_dir2_data_unused_t *)ptr;

					if (be16_to_cpu(dup->freetag)
						  == XFS_DIR2_DATA_FREE_TAG) {

						length = be16_to_cpu(dup->length);
						ptr += length;
						continue;
					}
					dep = (xfs_dir2_data_entry_t *)ptr;
					length =
					   dp->d_ops->data_entsize(dep->namelen);
					ptr += length;
				}
				/*
				 * Now set our real offset.
				 */
				curoff =
					xfs_dir2_db_off_to_byte(geo,
					    xfs_dir2_byte_to_db(geo, curoff),
					    (char *)ptr - (char *)hdr);
				if (ptr >= (char *)hdr + geo->blksize) {
					continue;
				}
			}
		}
		/*
		 * We have a pointer to an entry.
		 * Is it a live one?
		 */
		dup = (xfs_dir2_data_unused_t *)ptr;
		/*
		 * No, it's unused, skip over it.
		 */
		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
			length = be16_to_cpu(dup->length);
			ptr += length;
			curoff += length;
			continue;
		}

		dep = (xfs_dir2_data_entry_t *)ptr;
		length = dp->d_ops->data_entsize(dep->namelen);
		filetype = dp->d_ops->data_get_ftype(dep);

		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
			    be64_to_cpu(dep->inumber),
			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
			break;

		/*
		 * Advance to next entry in the block.
		 */
		ptr += length;
		curoff += length;
		/* bufsize may have just been a guess; don't go negative */
		bufsize = bufsize > length ? bufsize - length : 0;
	}

	/*
	 * All done.  Set output offset value to current offset.
	 */
	if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
		ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
	else
		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
	kmem_free(map_info);
	if (bp)
		xfs_trans_brelse(NULL, bp);
	return error;
}

/*
 * Read a directory.
 */
int
xfs_readdir(
	struct xfs_inode	*dp,
	struct dir_context	*ctx,
	size_t			bufsize)
{
	struct xfs_da_args	args = { NULL };
	int			rval;
	int			v;
	uint			lock_mode;

	trace_xfs_readdir(dp);

	if (XFS_FORCED_SHUTDOWN(dp->i_mount))
		return -EIO;

	ASSERT(S_ISDIR(dp->i_d.di_mode));
	XFS_STATS_INC(xs_dir_getdents);

	args.dp = dp;
	args.geo = dp->i_mount->m_dir_geo;

	lock_mode = xfs_ilock_data_map_shared(dp);
	if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
		rval = xfs_dir2_sf_getdents(&args, ctx);
	else if ((rval = xfs_dir2_isblock(&args, &v)))
		;
	else if (v)
		rval = xfs_dir2_block_getdents(&args, ctx);
	else
		rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
	xfs_iunlock(dp, lock_mode);

	return rval;
}