summaryrefslogtreecommitdiffstats
path: root/fs/xfs/xfs_dir2_readdir.c
blob: 06ac5a7de60a0497950801a66de31d2f059fb341 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * Copyright (c) 2013 Red Hat, Inc.
 * All Rights Reserved.
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_inode.h"
#include "xfs_dir2.h"
#include "xfs_dir2_priv.h"
#include "xfs_trace.h"
#include "xfs_bmap.h"
#include "xfs_trans.h"
#include "xfs_error.h"
#include "xfs_health.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_has_ftype(mp))
		return DT_UNKNOWN;

	if (filetype >= XFS_DIR3_FT_MAX)
		return DT_UNKNOWN;

	return xfs_dir3_filetype_table[filetype];
}

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 */
	struct xfs_mount	*mp = dp->i_mount;
	xfs_dir2_dataptr_t	off;		/* current entry's offset */
	xfs_dir2_sf_entry_t	*sfep;		/* shortform directory entry */
	struct xfs_dir2_sf_hdr	*sfp = dp->i_df.if_data;
	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_format == XFS_DINODE_FMT_LOCAL);
	ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
	ASSERT(sfp != NULL);

	/*
	 * 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.
	 * This relies on the fact that directories always start with the
	 * entries for "." and "..".
	 */
	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
			geo->data_entry_offset);
	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
			geo->data_entry_offset +
			xfs_dir2_data_entsize(mp, sizeof(".") - 1));

	/*
	 * 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 = xfs_dir2_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 = xfs_dir2_sf_nextentry(mp, sfp, sfep);
			continue;
		}

		ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
		filetype = xfs_dir2_sf_get_ftype(mp, sfep);
		ctx->pos = off & 0x7fffffff;
		if (XFS_IS_CORRUPT(dp->i_mount,
				   !xfs_dir2_namecheck(sfep->name,
						       sfep->namelen))) {
			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
			return -EFSCORRUPTED;
		}
		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
			    xfs_dir3_get_dtype(mp, filetype)))
			return 0;
		sfep = xfs_dir2_sf_nextentry(mp, 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,
	unsigned int		*lock_mode)
{
	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
	struct xfs_buf		*bp;		/* buffer for block */
	int			error;		/* error return value */
	int			wantoff;	/* starting block offset */
	xfs_off_t		cook;
	struct xfs_da_geometry	*geo = args->geo;
	unsigned int		offset, next_offset;
	unsigned int		end;

	/*
	 * 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(args->trans, dp, args->owner, &bp);
	if (error)
		return error;

	xfs_iunlock(dp, *lock_mode);
	*lock_mode = 0;

	/*
	 * 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);
	xfs_dir3_data_check(dp, bp);

	/*
	 * Loop over the data portion of the block.
	 * Each object is a real entry (dep) or an unused one (dup).
	 */
	end = xfs_dir3_data_end_offset(geo, bp->b_addr);
	for (offset = geo->data_entry_offset;
	     offset < end;
	     offset = next_offset) {
		struct xfs_dir2_data_unused	*dup = bp->b_addr + offset;
		struct xfs_dir2_data_entry	*dep = bp->b_addr + offset;
		uint8_t filetype;

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

		/*
		 * Bump pointer for the next iteration.
		 */
		next_offset = offset +
			xfs_dir2_data_entsize(dp->i_mount, dep->namelen);

		/*
		 * The entry is before the desired starting point, skip it.
		 */
		if (offset < wantoff)
			continue;

		cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset);

		ctx->pos = cook & 0x7fffffff;
		filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep);
		/*
		 * If it didn't fit, set the final offset to here & return.
		 */
		if (XFS_IS_CORRUPT(dp->i_mount,
				   !xfs_dir2_namecheck(dep->name,
						       dep->namelen))) {
			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
			error = -EFSCORRUPTED;
			goto out_rele;
		}
		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
			    be64_to_cpu(dep->inumber),
			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
			goto out_rele;
	}

	/*
	 * 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;
out_rele:
	xfs_trans_brelse(args->trans, bp);
	return error;
}

/*
 * Read a directory block and initiate readahead for blocks beyond that.
 * We maintain a sliding readahead window of the remaining space in the
 * buffer rounded up to the nearest block.
 */
STATIC int
xfs_dir2_leaf_readbuf(
	struct xfs_da_args	*args,
	size_t			bufsize,
	xfs_dir2_off_t		*cur_off,
	xfs_dablk_t		*ra_blk,
	struct xfs_buf		**bpp)
{
	struct xfs_inode	*dp = args->dp;
	struct xfs_buf		*bp = NULL;
	struct xfs_da_geometry	*geo = args->geo;
	struct xfs_ifork	*ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
	struct xfs_bmbt_irec	map;
	struct blk_plug		plug;
	xfs_dir2_off_t		new_off;
	xfs_dablk_t		next_ra;
	xfs_dablk_t		map_off;
	xfs_dablk_t		last_da;
	struct xfs_iext_cursor	icur;
	int			ra_want;
	int			error = 0;

	error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
	if (error)
		goto out;

	/*
	 * Look for mapped directory blocks at or above the current offset.
	 * Truncate down to the nearest directory block to start the scanning
	 * operation.
	 */
	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
		goto out;
	if (map.br_startoff >= last_da)
		goto out;
	xfs_trim_extent(&map, map_off, last_da - map_off);

	/* Read the directory block of that first mapping. */
	new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
	if (new_off > *cur_off)
		*cur_off = new_off;
	error = xfs_dir3_data_read(args->trans, dp, args->owner,
			map.br_startoff, 0, &bp);
	if (error)
		goto out;

	/*
	 * Start readahead for the next bufsize's worth of dir data blocks.
	 * We may have already issued readahead for some of that range;
	 * ra_blk tracks the last block we tried to read(ahead).
	 */
	ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
	if (*ra_blk >= last_da)
		goto out;
	else if (*ra_blk == 0)
		*ra_blk = map.br_startoff;
	next_ra = map.br_startoff + geo->fsbcount;
	if (next_ra >= last_da)
		goto out_no_ra;
	if (map.br_blockcount < geo->fsbcount &&
	    !xfs_iext_next_extent(ifp, &icur, &map))
		goto out_no_ra;
	if (map.br_startoff >= last_da)
		goto out_no_ra;
	xfs_trim_extent(&map, next_ra, last_da - next_ra);

	/* Start ra for each dir (not fs) block that has a mapping. */
	blk_start_plug(&plug);
	while (ra_want > 0) {
		next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
		while (ra_want > 0 &&
		       next_ra < map.br_startoff + map.br_blockcount) {
			if (next_ra >= last_da) {
				*ra_blk = last_da;
				break;
			}
			if (next_ra > *ra_blk) {
				xfs_dir3_data_readahead(dp, next_ra,
							XFS_DABUF_MAP_HOLE_OK);
				*ra_blk = next_ra;
			}
			ra_want -= geo->fsbcount;
			next_ra += geo->fsbcount;
		}
		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
			*ra_blk = last_da;
			break;
		}
	}
	blk_finish_plug(&plug);

out:
	*bpp = bp;
	return error;
out_no_ra:
	*ra_blk = last_da;
	goto out;
}

/*
 * 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,
	unsigned int		*lock_mode)
{
	struct xfs_inode	*dp = args->dp;
	struct xfs_mount	*mp = dp->i_mount;
	struct xfs_buf		*bp = NULL;	/* data block buffer */
	xfs_dir2_data_entry_t	*dep;		/* data entry */
	xfs_dir2_data_unused_t	*dup;		/* unused entry */
	struct xfs_da_geometry	*geo = args->geo;
	xfs_dablk_t		rablk = 0;	/* current readahead block */
	xfs_dir2_off_t		curoff;		/* current overall offset */
	int			length;		/* temporary length value */
	int			byteoff;	/* offset in current block */
	unsigned int		offset = 0;
	int			error = 0;	/* error return value */

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

	/*
	 * 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);

	/*
	 * 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 || offset >= geo->blksize) {
			if (bp) {
				xfs_trans_brelse(args->trans, bp);
				bp = NULL;
			}

			if (*lock_mode == 0)
				*lock_mode = xfs_ilock_data_map_shared(dp);
			error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
					&rablk, &bp);
			if (error || !bp)
				break;

			xfs_iunlock(dp, *lock_mode);
			*lock_mode = 0;

			xfs_dir3_data_check(dp, bp);
			/*
			 * Find our position in the block.
			 */
			offset = geo->data_entry_offset;
			byteoff = xfs_dir2_byte_to_off(geo, curoff);
			/*
			 * Skip past the header.
			 */
			if (byteoff == 0)
				curoff += geo->data_entry_offset;
			/*
			 * Skip past entries until we reach our offset.
			 */
			else {
				while (offset < byteoff) {
					dup = bp->b_addr + offset;

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

						length = be16_to_cpu(dup->length);
						offset += length;
						continue;
					}
					dep = bp->b_addr + offset;
					length = xfs_dir2_data_entsize(mp,
							dep->namelen);
					offset += length;
				}
				/*
				 * Now set our real offset.
				 */
				curoff =
					xfs_dir2_db_off_to_byte(geo,
					    xfs_dir2_byte_to_db(geo, curoff),
					    offset);
				if (offset >= geo->blksize)
					continue;
			}
		}

		/*
		 * We have a pointer to an entry.  Is it a live one?
		 */
		dup = bp->b_addr + offset;

		/*
		 * No, it's unused, skip over it.
		 */
		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
			length = be16_to_cpu(dup->length);
			offset += length;
			curoff += length;
			continue;
		}

		dep = bp->b_addr + offset;
		length = xfs_dir2_data_entsize(mp, dep->namelen);
		filetype = xfs_dir2_data_get_ftype(mp, dep);

		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
		if (XFS_IS_CORRUPT(dp->i_mount,
				   !xfs_dir2_namecheck(dep->name,
						       dep->namelen))) {
			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
			error = -EFSCORRUPTED;
			break;
		}
		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.
		 */
		offset += 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;
	if (bp)
		xfs_trans_brelse(args->trans, bp);
	return error;
}

/*
 * Read a directory.
 *
 * If supplied, the transaction collects locked dir buffers to avoid
 * nested buffer deadlocks.  This function does not dirty the
 * transaction.  The caller must hold the IOLOCK (shared or exclusive)
 * before calling this function.
 */
int
xfs_readdir(
	struct xfs_trans	*tp,
	struct xfs_inode	*dp,
	struct dir_context	*ctx,
	size_t			bufsize)
{
	struct xfs_da_args	args = { NULL };
	unsigned int		lock_mode;
	int			error;

	trace_xfs_readdir(dp);

	if (xfs_is_shutdown(dp->i_mount))
		return -EIO;
	if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
		return -EIO;

	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
	xfs_assert_ilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL);
	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);

	args.dp = dp;
	args.geo = dp->i_mount->m_dir_geo;
	args.trans = tp;
	args.owner = dp->i_ino;

	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
		return xfs_dir2_sf_getdents(&args, ctx);

	lock_mode = xfs_ilock_data_map_shared(dp);
	switch (xfs_dir2_format(&args, &error)) {
	case XFS_DIR2_FMT_BLOCK:
		error = xfs_dir2_block_getdents(&args, ctx, &lock_mode);
		break;
	case XFS_DIR2_FMT_LEAF:
	case XFS_DIR2_FMT_NODE:
		error = xfs_dir2_leaf_getdents(&args, ctx, bufsize, &lock_mode);
		break;
	default:
		break;
	}

	if (lock_mode)
		xfs_iunlock(dp, lock_mode);
	return error;
}