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  #include "xfs_health.h"
22  
23  /*
24   * Directory file type support functions
25   */
26  static unsigned char xfs_dir3_filetype_table[] = {
27  	DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK,
28  	DT_FIFO, DT_SOCK, DT_LNK, DT_WHT,
29  };
30  
31  unsigned char
xfs_dir3_get_dtype(struct xfs_mount * mp,uint8_t filetype)32  xfs_dir3_get_dtype(
33  	struct xfs_mount	*mp,
34  	uint8_t			filetype)
35  {
36  	if (!xfs_has_ftype(mp))
37  		return DT_UNKNOWN;
38  
39  	if (filetype >= XFS_DIR3_FT_MAX)
40  		return DT_UNKNOWN;
41  
42  	return xfs_dir3_filetype_table[filetype];
43  }
44  
45  STATIC int
xfs_dir2_sf_getdents(struct xfs_da_args * args,struct dir_context * ctx)46  xfs_dir2_sf_getdents(
47  	struct xfs_da_args	*args,
48  	struct dir_context	*ctx)
49  {
50  	int			i;		/* shortform entry number */
51  	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
52  	struct xfs_mount	*mp = dp->i_mount;
53  	xfs_dir2_dataptr_t	off;		/* current entry's offset */
54  	xfs_dir2_sf_entry_t	*sfep;		/* shortform directory entry */
55  	struct xfs_dir2_sf_hdr	*sfp = dp->i_df.if_data;
56  	xfs_dir2_dataptr_t	dot_offset;
57  	xfs_dir2_dataptr_t	dotdot_offset;
58  	xfs_ino_t		ino;
59  	struct xfs_da_geometry	*geo = args->geo;
60  
61  	ASSERT(dp->i_df.if_format == XFS_DINODE_FMT_LOCAL);
62  	ASSERT(dp->i_df.if_bytes == dp->i_disk_size);
63  	ASSERT(sfp != NULL);
64  
65  	/*
66  	 * If the block number in the offset is out of range, we're done.
67  	 */
68  	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
69  		return 0;
70  
71  	/*
72  	 * Precalculate offsets for "." and ".." as we will always need them.
73  	 * This relies on the fact that directories always start with the
74  	 * entries for "." and "..".
75  	 */
76  	dot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
77  			geo->data_entry_offset);
78  	dotdot_offset = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
79  			geo->data_entry_offset +
80  			xfs_dir2_data_entsize(mp, sizeof(".") - 1));
81  
82  	/*
83  	 * Put . entry unless we're starting past it.
84  	 */
85  	if (ctx->pos <= dot_offset) {
86  		ctx->pos = dot_offset & 0x7fffffff;
87  		if (!dir_emit(ctx, ".", 1, dp->i_ino, DT_DIR))
88  			return 0;
89  	}
90  
91  	/*
92  	 * Put .. entry unless we're starting past it.
93  	 */
94  	if (ctx->pos <= dotdot_offset) {
95  		ino = xfs_dir2_sf_get_parent_ino(sfp);
96  		ctx->pos = dotdot_offset & 0x7fffffff;
97  		if (!dir_emit(ctx, "..", 2, ino, DT_DIR))
98  			return 0;
99  	}
100  
101  	/*
102  	 * Loop while there are more entries and put'ing works.
103  	 */
104  	sfep = xfs_dir2_sf_firstentry(sfp);
105  	for (i = 0; i < sfp->count; i++) {
106  		uint8_t filetype;
107  
108  		off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
109  				xfs_dir2_sf_get_offset(sfep));
110  
111  		if (ctx->pos > off) {
112  			sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
113  			continue;
114  		}
115  
116  		ino = xfs_dir2_sf_get_ino(mp, sfp, sfep);
117  		filetype = xfs_dir2_sf_get_ftype(mp, sfep);
118  		ctx->pos = off & 0x7fffffff;
119  		if (XFS_IS_CORRUPT(dp->i_mount,
120  				   !xfs_dir2_namecheck(sfep->name,
121  						       sfep->namelen))) {
122  			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
123  			return -EFSCORRUPTED;
124  		}
125  		if (!dir_emit(ctx, (char *)sfep->name, sfep->namelen, ino,
126  			    xfs_dir3_get_dtype(mp, filetype)))
127  			return 0;
128  		sfep = xfs_dir2_sf_nextentry(mp, sfp, sfep);
129  	}
130  
131  	ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
132  								0x7fffffff;
133  	return 0;
134  }
135  
136  /*
137   * Readdir for block directories.
138   */
139  STATIC int
xfs_dir2_block_getdents(struct xfs_da_args * args,struct dir_context * ctx,unsigned int * lock_mode)140  xfs_dir2_block_getdents(
141  	struct xfs_da_args	*args,
142  	struct dir_context	*ctx,
143  	unsigned int		*lock_mode)
144  {
145  	struct xfs_inode	*dp = args->dp;	/* incore directory inode */
146  	struct xfs_buf		*bp;		/* buffer for block */
147  	int			error;		/* error return value */
148  	int			wantoff;	/* starting block offset */
149  	xfs_off_t		cook;
150  	struct xfs_da_geometry	*geo = args->geo;
151  	unsigned int		offset, next_offset;
152  	unsigned int		end;
153  
154  	/*
155  	 * If the block number in the offset is out of range, we're done.
156  	 */
157  	if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
158  		return 0;
159  
160  	error = xfs_dir3_block_read(args->trans, dp, args->owner, &bp);
161  	if (error)
162  		return error;
163  
164  	xfs_iunlock(dp, *lock_mode);
165  	*lock_mode = 0;
166  
167  	/*
168  	 * Extract the byte offset we start at from the seek pointer.
169  	 * We'll skip entries before this.
170  	 */
171  	wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
172  	xfs_dir3_data_check(dp, bp);
173  
174  	/*
175  	 * Loop over the data portion of the block.
176  	 * Each object is a real entry (dep) or an unused one (dup).
177  	 */
178  	end = xfs_dir3_data_end_offset(geo, bp->b_addr);
179  	for (offset = geo->data_entry_offset;
180  	     offset < end;
181  	     offset = next_offset) {
182  		struct xfs_dir2_data_unused	*dup = bp->b_addr + offset;
183  		struct xfs_dir2_data_entry	*dep = bp->b_addr + offset;
184  		uint8_t filetype;
185  
186  		/*
187  		 * Unused, skip it.
188  		 */
189  		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
190  			next_offset = offset + be16_to_cpu(dup->length);
191  			continue;
192  		}
193  
194  		/*
195  		 * Bump pointer for the next iteration.
196  		 */
197  		next_offset = offset +
198  			xfs_dir2_data_entsize(dp->i_mount, dep->namelen);
199  
200  		/*
201  		 * The entry is before the desired starting point, skip it.
202  		 */
203  		if (offset < wantoff)
204  			continue;
205  
206  		cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk, offset);
207  
208  		ctx->pos = cook & 0x7fffffff;
209  		filetype = xfs_dir2_data_get_ftype(dp->i_mount, dep);
210  		/*
211  		 * If it didn't fit, set the final offset to here & return.
212  		 */
213  		if (XFS_IS_CORRUPT(dp->i_mount,
214  				   !xfs_dir2_namecheck(dep->name,
215  						       dep->namelen))) {
216  			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
217  			error = -EFSCORRUPTED;
218  			goto out_rele;
219  		}
220  		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
221  			    be64_to_cpu(dep->inumber),
222  			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
223  			goto out_rele;
224  	}
225  
226  	/*
227  	 * Reached the end of the block.
228  	 * Set the offset to a non-existent block 1 and return.
229  	 */
230  	ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
231  								0x7fffffff;
232  out_rele:
233  	xfs_trans_brelse(args->trans, bp);
234  	return error;
235  }
236  
237  /*
238   * Read a directory block and initiate readahead for blocks beyond that.
239   * We maintain a sliding readahead window of the remaining space in the
240   * buffer rounded up to the nearest block.
241   */
242  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)243  xfs_dir2_leaf_readbuf(
244  	struct xfs_da_args	*args,
245  	size_t			bufsize,
246  	xfs_dir2_off_t		*cur_off,
247  	xfs_dablk_t		*ra_blk,
248  	struct xfs_buf		**bpp)
249  {
250  	struct xfs_inode	*dp = args->dp;
251  	struct xfs_buf		*bp = NULL;
252  	struct xfs_da_geometry	*geo = args->geo;
253  	struct xfs_ifork	*ifp = xfs_ifork_ptr(dp, XFS_DATA_FORK);
254  	struct xfs_bmbt_irec	map;
255  	struct blk_plug		plug;
256  	xfs_dir2_off_t		new_off;
257  	xfs_dablk_t		next_ra;
258  	xfs_dablk_t		map_off;
259  	xfs_dablk_t		last_da;
260  	struct xfs_iext_cursor	icur;
261  	int			ra_want;
262  	int			error = 0;
263  
264  	error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
265  	if (error)
266  		goto out;
267  
268  	/*
269  	 * Look for mapped directory blocks at or above the current offset.
270  	 * Truncate down to the nearest directory block to start the scanning
271  	 * operation.
272  	 */
273  	last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
274  	map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
275  	if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
276  		goto out;
277  	if (map.br_startoff >= last_da)
278  		goto out;
279  	xfs_trim_extent(&map, map_off, last_da - map_off);
280  
281  	/* Read the directory block of that first mapping. */
282  	new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
283  	if (new_off > *cur_off)
284  		*cur_off = new_off;
285  	error = xfs_dir3_data_read(args->trans, dp, args->owner,
286  			map.br_startoff, 0, &bp);
287  	if (error)
288  		goto out;
289  
290  	/*
291  	 * Start readahead for the next bufsize's worth of dir data blocks.
292  	 * We may have already issued readahead for some of that range;
293  	 * ra_blk tracks the last block we tried to read(ahead).
294  	 */
295  	ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
296  	if (*ra_blk >= last_da)
297  		goto out;
298  	else if (*ra_blk == 0)
299  		*ra_blk = map.br_startoff;
300  	next_ra = map.br_startoff + geo->fsbcount;
301  	if (next_ra >= last_da)
302  		goto out_no_ra;
303  	if (map.br_blockcount < geo->fsbcount &&
304  	    !xfs_iext_next_extent(ifp, &icur, &map))
305  		goto out_no_ra;
306  	if (map.br_startoff >= last_da)
307  		goto out_no_ra;
308  	xfs_trim_extent(&map, next_ra, last_da - next_ra);
309  
310  	/* Start ra for each dir (not fs) block that has a mapping. */
311  	blk_start_plug(&plug);
312  	while (ra_want > 0) {
313  		next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
314  		while (ra_want > 0 &&
315  		       next_ra < map.br_startoff + map.br_blockcount) {
316  			if (next_ra >= last_da) {
317  				*ra_blk = last_da;
318  				break;
319  			}
320  			if (next_ra > *ra_blk) {
321  				xfs_dir3_data_readahead(dp, next_ra,
322  							XFS_DABUF_MAP_HOLE_OK);
323  				*ra_blk = next_ra;
324  			}
325  			ra_want -= geo->fsbcount;
326  			next_ra += geo->fsbcount;
327  		}
328  		if (!xfs_iext_next_extent(ifp, &icur, &map)) {
329  			*ra_blk = last_da;
330  			break;
331  		}
332  	}
333  	blk_finish_plug(&plug);
334  
335  out:
336  	*bpp = bp;
337  	return error;
338  out_no_ra:
339  	*ra_blk = last_da;
340  	goto out;
341  }
342  
343  /*
344   * Getdents (readdir) for leaf and node directories.
345   * This reads the data blocks only, so is the same for both forms.
346   */
347  STATIC int
xfs_dir2_leaf_getdents(struct xfs_da_args * args,struct dir_context * ctx,size_t bufsize,unsigned int * lock_mode)348  xfs_dir2_leaf_getdents(
349  	struct xfs_da_args	*args,
350  	struct dir_context	*ctx,
351  	size_t			bufsize,
352  	unsigned int		*lock_mode)
353  {
354  	struct xfs_inode	*dp = args->dp;
355  	struct xfs_mount	*mp = dp->i_mount;
356  	struct xfs_buf		*bp = NULL;	/* data block buffer */
357  	xfs_dir2_data_entry_t	*dep;		/* data entry */
358  	xfs_dir2_data_unused_t	*dup;		/* unused entry */
359  	struct xfs_da_geometry	*geo = args->geo;
360  	xfs_dablk_t		rablk = 0;	/* current readahead block */
361  	xfs_dir2_off_t		curoff;		/* current overall offset */
362  	int			length;		/* temporary length value */
363  	int			byteoff;	/* offset in current block */
364  	unsigned int		offset = 0;
365  	int			error = 0;	/* error return value */
366  
367  	/*
368  	 * If the offset is at or past the largest allowed value,
369  	 * give up right away.
370  	 */
371  	if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
372  		return 0;
373  
374  	/*
375  	 * Inside the loop we keep the main offset value as a byte offset
376  	 * in the directory file.
377  	 */
378  	curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
379  
380  	/*
381  	 * Loop over directory entries until we reach the end offset.
382  	 * Get more blocks and readahead as necessary.
383  	 */
384  	while (curoff < XFS_DIR2_LEAF_OFFSET) {
385  		uint8_t filetype;
386  
387  		/*
388  		 * If we have no buffer, or we're off the end of the
389  		 * current buffer, need to get another one.
390  		 */
391  		if (!bp || offset >= geo->blksize) {
392  			if (bp) {
393  				xfs_trans_brelse(args->trans, bp);
394  				bp = NULL;
395  			}
396  
397  			if (*lock_mode == 0)
398  				*lock_mode = xfs_ilock_data_map_shared(dp);
399  			error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
400  					&rablk, &bp);
401  			if (error || !bp)
402  				break;
403  
404  			xfs_iunlock(dp, *lock_mode);
405  			*lock_mode = 0;
406  
407  			xfs_dir3_data_check(dp, bp);
408  			/*
409  			 * Find our position in the block.
410  			 */
411  			offset = geo->data_entry_offset;
412  			byteoff = xfs_dir2_byte_to_off(geo, curoff);
413  			/*
414  			 * Skip past the header.
415  			 */
416  			if (byteoff == 0)
417  				curoff += geo->data_entry_offset;
418  			/*
419  			 * Skip past entries until we reach our offset.
420  			 */
421  			else {
422  				while (offset < byteoff) {
423  					dup = bp->b_addr + offset;
424  
425  					if (be16_to_cpu(dup->freetag)
426  						  == XFS_DIR2_DATA_FREE_TAG) {
427  
428  						length = be16_to_cpu(dup->length);
429  						offset += length;
430  						continue;
431  					}
432  					dep = bp->b_addr + offset;
433  					length = xfs_dir2_data_entsize(mp,
434  							dep->namelen);
435  					offset += length;
436  				}
437  				/*
438  				 * Now set our real offset.
439  				 */
440  				curoff =
441  					xfs_dir2_db_off_to_byte(geo,
442  					    xfs_dir2_byte_to_db(geo, curoff),
443  					    offset);
444  				if (offset >= geo->blksize)
445  					continue;
446  			}
447  		}
448  
449  		/*
450  		 * We have a pointer to an entry.  Is it a live one?
451  		 */
452  		dup = bp->b_addr + offset;
453  
454  		/*
455  		 * No, it's unused, skip over it.
456  		 */
457  		if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
458  			length = be16_to_cpu(dup->length);
459  			offset += length;
460  			curoff += length;
461  			continue;
462  		}
463  
464  		dep = bp->b_addr + offset;
465  		length = xfs_dir2_data_entsize(mp, dep->namelen);
466  		filetype = xfs_dir2_data_get_ftype(mp, dep);
467  
468  		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
469  		if (XFS_IS_CORRUPT(dp->i_mount,
470  				   !xfs_dir2_namecheck(dep->name,
471  						       dep->namelen))) {
472  			xfs_dirattr_mark_sick(dp, XFS_DATA_FORK);
473  			error = -EFSCORRUPTED;
474  			break;
475  		}
476  		if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
477  			    be64_to_cpu(dep->inumber),
478  			    xfs_dir3_get_dtype(dp->i_mount, filetype)))
479  			break;
480  
481  		/*
482  		 * Advance to next entry in the block.
483  		 */
484  		offset += length;
485  		curoff += length;
486  		/* bufsize may have just been a guess; don't go negative */
487  		bufsize = bufsize > length ? bufsize - length : 0;
488  	}
489  
490  	/*
491  	 * All done.  Set output offset value to current offset.
492  	 */
493  	if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
494  		ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
495  	else
496  		ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
497  	if (bp)
498  		xfs_trans_brelse(args->trans, bp);
499  	return error;
500  }
501  
502  /*
503   * Read a directory.
504   *
505   * If supplied, the transaction collects locked dir buffers to avoid
506   * nested buffer deadlocks.  This function does not dirty the
507   * transaction.  The caller must hold the IOLOCK (shared or exclusive)
508   * before calling this function.
509   */
510  int
xfs_readdir(struct xfs_trans * tp,struct xfs_inode * dp,struct dir_context * ctx,size_t bufsize)511  xfs_readdir(
512  	struct xfs_trans	*tp,
513  	struct xfs_inode	*dp,
514  	struct dir_context	*ctx,
515  	size_t			bufsize)
516  {
517  	struct xfs_da_args	args = { NULL };
518  	unsigned int		lock_mode;
519  	int			error;
520  
521  	trace_xfs_readdir(dp);
522  
523  	if (xfs_is_shutdown(dp->i_mount))
524  		return -EIO;
525  	if (xfs_ifork_zapped(dp, XFS_DATA_FORK))
526  		return -EIO;
527  
528  	ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
529  	xfs_assert_ilocked(dp, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL);
530  	XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
531  
532  	args.dp = dp;
533  	args.geo = dp->i_mount->m_dir_geo;
534  	args.trans = tp;
535  	args.owner = dp->i_ino;
536  
537  	if (dp->i_df.if_format == XFS_DINODE_FMT_LOCAL)
538  		return xfs_dir2_sf_getdents(&args, ctx);
539  
540  	lock_mode = xfs_ilock_data_map_shared(dp);
541  	switch (xfs_dir2_format(&args, &error)) {
542  	case XFS_DIR2_FMT_BLOCK:
543  		error = xfs_dir2_block_getdents(&args, ctx, &lock_mode);
544  		break;
545  	case XFS_DIR2_FMT_LEAF:
546  	case XFS_DIR2_FMT_NODE:
547  		error = xfs_dir2_leaf_getdents(&args, ctx, bufsize, &lock_mode);
548  		break;
549  	default:
550  		break;
551  	}
552  
553  	if (lock_mode)
554  		xfs_iunlock(dp, lock_mode);
555  	return error;
556  }
557