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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 */
39static 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
44unsigned char
45xfs_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
58STATIC int
59xfs_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 */
147STATIC int
148xfs_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_data_entry_t *dep; /* block data entry */
156 xfs_dir2_data_unused_t *dup; /* block unused entry */
157 char *endptr; /* end of the data entries */
158 int error; /* error return value */
159 char *ptr; /* current data entry */
160 int wantoff; /* starting block offset */
161 xfs_off_t cook;
162 struct xfs_da_geometry *geo = args->geo;
163 int lock_mode;
164
165 /*
166 * If the block number in the offset is out of range, we're done.
167 */
168 if (xfs_dir2_dataptr_to_db(geo, ctx->pos) > geo->datablk)
169 return 0;
170
171 lock_mode = xfs_ilock_data_map_shared(dp);
172 error = xfs_dir3_block_read(args->trans, dp, &bp);
173 xfs_iunlock(dp, lock_mode);
174 if (error)
175 return error;
176
177 /*
178 * Extract the byte offset we start at from the seek pointer.
179 * We'll skip entries before this.
180 */
181 wantoff = xfs_dir2_dataptr_to_off(geo, ctx->pos);
182 hdr = bp->b_addr;
183 xfs_dir3_data_check(dp, bp);
184 /*
185 * Set up values for the loop.
186 */
187 ptr = (char *)dp->d_ops->data_entry_p(hdr);
188 endptr = xfs_dir3_data_endp(geo, hdr);
189
190 /*
191 * Loop over the data portion of the block.
192 * Each object is a real entry (dep) or an unused one (dup).
193 */
194 while (ptr < endptr) {
195 uint8_t filetype;
196
197 dup = (xfs_dir2_data_unused_t *)ptr;
198 /*
199 * Unused, skip it.
200 */
201 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
202 ptr += be16_to_cpu(dup->length);
203 continue;
204 }
205
206 dep = (xfs_dir2_data_entry_t *)ptr;
207
208 /*
209 * Bump pointer for the next iteration.
210 */
211 ptr += dp->d_ops->data_entsize(dep->namelen);
212 /*
213 * The entry is before the desired starting point, skip it.
214 */
215 if ((char *)dep - (char *)hdr < wantoff)
216 continue;
217
218 cook = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
219 (char *)dep - (char *)hdr);
220
221 ctx->pos = cook & 0x7fffffff;
222 filetype = dp->d_ops->data_get_ftype(dep);
223 /*
224 * If it didn't fit, set the final offset to here & return.
225 */
226 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
227 be64_to_cpu(dep->inumber),
228 xfs_dir3_get_dtype(dp->i_mount, filetype))) {
229 xfs_trans_brelse(args->trans, bp);
230 return 0;
231 }
232 }
233
234 /*
235 * Reached the end of the block.
236 * Set the offset to a non-existent block 1 and return.
237 */
238 ctx->pos = xfs_dir2_db_off_to_dataptr(geo, geo->datablk + 1, 0) &
239 0x7fffffff;
240 xfs_trans_brelse(args->trans, bp);
241 return 0;
242}
243
244/*
245 * Read a directory block and initiate readahead for blocks beyond that.
246 * We maintain a sliding readahead window of the remaining space in the
247 * buffer rounded up to the nearest block.
248 */
249STATIC int
250xfs_dir2_leaf_readbuf(
251 struct xfs_da_args *args,
252 size_t bufsize,
253 xfs_dir2_off_t *cur_off,
254 xfs_dablk_t *ra_blk,
255 struct xfs_buf **bpp)
256{
257 struct xfs_inode *dp = args->dp;
258 struct xfs_buf *bp = NULL;
259 struct xfs_da_geometry *geo = args->geo;
260 struct xfs_ifork *ifp = XFS_IFORK_PTR(dp, XFS_DATA_FORK);
261 struct xfs_bmbt_irec map;
262 struct blk_plug plug;
263 xfs_dir2_off_t new_off;
264 xfs_dablk_t next_ra;
265 xfs_dablk_t map_off;
266 xfs_dablk_t last_da;
267 struct xfs_iext_cursor icur;
268 int ra_want;
269 int error = 0;
270
271 if (!(ifp->if_flags & XFS_IFEXTENTS)) {
272 error = xfs_iread_extents(args->trans, dp, XFS_DATA_FORK);
273 if (error)
274 goto out;
275 }
276
277 /*
278 * Look for mapped directory blocks at or above the current offset.
279 * Truncate down to the nearest directory block to start the scanning
280 * operation.
281 */
282 last_da = xfs_dir2_byte_to_da(geo, XFS_DIR2_LEAF_OFFSET);
283 map_off = xfs_dir2_db_to_da(geo, xfs_dir2_byte_to_db(geo, *cur_off));
284 if (!xfs_iext_lookup_extent(dp, ifp, map_off, &icur, &map))
285 goto out;
286 if (map.br_startoff >= last_da)
287 goto out;
288 xfs_trim_extent(&map, map_off, last_da - map_off);
289
290 /* Read the directory block of that first mapping. */
291 new_off = xfs_dir2_da_to_byte(geo, map.br_startoff);
292 if (new_off > *cur_off)
293 *cur_off = new_off;
294 error = xfs_dir3_data_read(args->trans, dp, map.br_startoff, -1, &bp);
295 if (error)
296 goto out;
297
298 /*
299 * Start readahead for the next bufsize's worth of dir data blocks.
300 * We may have already issued readahead for some of that range;
301 * ra_blk tracks the last block we tried to read(ahead).
302 */
303 ra_want = howmany(bufsize + geo->blksize, (1 << geo->fsblog));
304 if (*ra_blk >= last_da)
305 goto out;
306 else if (*ra_blk == 0)
307 *ra_blk = map.br_startoff;
308 next_ra = map.br_startoff + geo->fsbcount;
309 if (next_ra >= last_da)
310 goto out_no_ra;
311 if (map.br_blockcount < geo->fsbcount &&
312 !xfs_iext_next_extent(ifp, &icur, &map))
313 goto out_no_ra;
314 if (map.br_startoff >= last_da)
315 goto out_no_ra;
316 xfs_trim_extent(&map, next_ra, last_da - next_ra);
317
318 /* Start ra for each dir (not fs) block that has a mapping. */
319 blk_start_plug(&plug);
320 while (ra_want > 0) {
321 next_ra = roundup((xfs_dablk_t)map.br_startoff, geo->fsbcount);
322 while (ra_want > 0 &&
323 next_ra < map.br_startoff + map.br_blockcount) {
324 if (next_ra >= last_da) {
325 *ra_blk = last_da;
326 break;
327 }
328 if (next_ra > *ra_blk) {
329 xfs_dir3_data_readahead(dp, next_ra, -2);
330 *ra_blk = next_ra;
331 }
332 ra_want -= geo->fsbcount;
333 next_ra += geo->fsbcount;
334 }
335 if (!xfs_iext_next_extent(ifp, &icur, &map)) {
336 *ra_blk = last_da;
337 break;
338 }
339 }
340 blk_finish_plug(&plug);
341
342out:
343 *bpp = bp;
344 return error;
345out_no_ra:
346 *ra_blk = last_da;
347 goto out;
348}
349
350/*
351 * Getdents (readdir) for leaf and node directories.
352 * This reads the data blocks only, so is the same for both forms.
353 */
354STATIC int
355xfs_dir2_leaf_getdents(
356 struct xfs_da_args *args,
357 struct dir_context *ctx,
358 size_t bufsize)
359{
360 struct xfs_inode *dp = args->dp;
361 struct xfs_buf *bp = NULL; /* data block buffer */
362 xfs_dir2_data_hdr_t *hdr; /* data block header */
363 xfs_dir2_data_entry_t *dep; /* data entry */
364 xfs_dir2_data_unused_t *dup; /* unused entry */
365 char *ptr = NULL; /* pointer to current data */
366 struct xfs_da_geometry *geo = args->geo;
367 xfs_dablk_t rablk = 0; /* current readahead block */
368 xfs_dir2_off_t curoff; /* current overall offset */
369 int length; /* temporary length value */
370 int byteoff; /* offset in current block */
371 int lock_mode;
372 int error = 0; /* error return value */
373
374 /*
375 * If the offset is at or past the largest allowed value,
376 * give up right away.
377 */
378 if (ctx->pos >= XFS_DIR2_MAX_DATAPTR)
379 return 0;
380
381 /*
382 * Inside the loop we keep the main offset value as a byte offset
383 * in the directory file.
384 */
385 curoff = xfs_dir2_dataptr_to_byte(ctx->pos);
386
387 /*
388 * Loop over directory entries until we reach the end offset.
389 * Get more blocks and readahead as necessary.
390 */
391 while (curoff < XFS_DIR2_LEAF_OFFSET) {
392 uint8_t filetype;
393
394 /*
395 * If we have no buffer, or we're off the end of the
396 * current buffer, need to get another one.
397 */
398 if (!bp || ptr >= (char *)bp->b_addr + geo->blksize) {
399 if (bp) {
400 xfs_trans_brelse(args->trans, bp);
401 bp = NULL;
402 }
403
404 lock_mode = xfs_ilock_data_map_shared(dp);
405 error = xfs_dir2_leaf_readbuf(args, bufsize, &curoff,
406 &rablk, &bp);
407 xfs_iunlock(dp, lock_mode);
408 if (error || !bp)
409 break;
410
411 hdr = bp->b_addr;
412 xfs_dir3_data_check(dp, bp);
413 /*
414 * Find our position in the block.
415 */
416 ptr = (char *)dp->d_ops->data_entry_p(hdr);
417 byteoff = xfs_dir2_byte_to_off(geo, curoff);
418 /*
419 * Skip past the header.
420 */
421 if (byteoff == 0)
422 curoff += dp->d_ops->data_entry_offset;
423 /*
424 * Skip past entries until we reach our offset.
425 */
426 else {
427 while ((char *)ptr - (char *)hdr < byteoff) {
428 dup = (xfs_dir2_data_unused_t *)ptr;
429
430 if (be16_to_cpu(dup->freetag)
431 == XFS_DIR2_DATA_FREE_TAG) {
432
433 length = be16_to_cpu(dup->length);
434 ptr += length;
435 continue;
436 }
437 dep = (xfs_dir2_data_entry_t *)ptr;
438 length =
439 dp->d_ops->data_entsize(dep->namelen);
440 ptr += length;
441 }
442 /*
443 * Now set our real offset.
444 */
445 curoff =
446 xfs_dir2_db_off_to_byte(geo,
447 xfs_dir2_byte_to_db(geo, curoff),
448 (char *)ptr - (char *)hdr);
449 if (ptr >= (char *)hdr + geo->blksize) {
450 continue;
451 }
452 }
453 }
454 /*
455 * We have a pointer to an entry.
456 * Is it a live one?
457 */
458 dup = (xfs_dir2_data_unused_t *)ptr;
459 /*
460 * No, it's unused, skip over it.
461 */
462 if (be16_to_cpu(dup->freetag) == XFS_DIR2_DATA_FREE_TAG) {
463 length = be16_to_cpu(dup->length);
464 ptr += length;
465 curoff += length;
466 continue;
467 }
468
469 dep = (xfs_dir2_data_entry_t *)ptr;
470 length = dp->d_ops->data_entsize(dep->namelen);
471 filetype = dp->d_ops->data_get_ftype(dep);
472
473 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
474 if (!dir_emit(ctx, (char *)dep->name, dep->namelen,
475 be64_to_cpu(dep->inumber),
476 xfs_dir3_get_dtype(dp->i_mount, filetype)))
477 break;
478
479 /*
480 * Advance to next entry in the block.
481 */
482 ptr += length;
483 curoff += length;
484 /* bufsize may have just been a guess; don't go negative */
485 bufsize = bufsize > length ? bufsize - length : 0;
486 }
487
488 /*
489 * All done. Set output offset value to current offset.
490 */
491 if (curoff > xfs_dir2_dataptr_to_byte(XFS_DIR2_MAX_DATAPTR))
492 ctx->pos = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
493 else
494 ctx->pos = xfs_dir2_byte_to_dataptr(curoff) & 0x7fffffff;
495 if (bp)
496 xfs_trans_brelse(args->trans, bp);
497 return error;
498}
499
500/*
501 * Read a directory.
502 *
503 * If supplied, the transaction collects locked dir buffers to avoid
504 * nested buffer deadlocks. This function does not dirty the
505 * transaction. The caller should ensure that the inode is locked
506 * before calling this function.
507 */
508int
509xfs_readdir(
510 struct xfs_trans *tp,
511 struct xfs_inode *dp,
512 struct dir_context *ctx,
513 size_t bufsize)
514{
515 struct xfs_da_args args = { NULL };
516 int rval;
517 int v;
518
519 trace_xfs_readdir(dp);
520
521 if (XFS_FORCED_SHUTDOWN(dp->i_mount))
522 return -EIO;
523
524 ASSERT(S_ISDIR(VFS_I(dp)->i_mode));
525 XFS_STATS_INC(dp->i_mount, xs_dir_getdents);
526
527 args.dp = dp;
528 args.geo = dp->i_mount->m_dir_geo;
529 args.trans = tp;
530
531 if (dp->i_d.di_format == XFS_DINODE_FMT_LOCAL)
532 rval = xfs_dir2_sf_getdents(&args, ctx);
533 else if ((rval = xfs_dir2_isblock(&args, &v)))
534 ;
535 else if (v)
536 rval = xfs_dir2_block_getdents(&args, ctx);
537 else
538 rval = xfs_dir2_leaf_getdents(&args, ctx, bufsize);
539
540 return rval;
541}
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 */
26static 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
31unsigned char
32xfs_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
45STATIC int
46xfs_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 */
139STATIC int
140xfs_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;
232out_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 */
242STATIC int
243xfs_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
335out:
336 *bpp = bp;
337 return error;
338out_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 */
347STATIC int
348xfs_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 */
510int
511xfs_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}