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Linux 3.12.5
[linux/fpc-iii.git] / fs / nilfs2 / dir.c
blob197a63e9d10215b54e28179b7976e6c0b56b5384
1 /*
2 * dir.c - NILFS directory entry operations
3 *
4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 * Modified for NILFS by Amagai Yoshiji <amagai@osrg.net>
21 */
22 /*
23 * linux/fs/ext2/dir.c
24 *
25 * Copyright (C) 1992, 1993, 1994, 1995
26 * Remy Card (card@masi.ibp.fr)
27 * Laboratoire MASI - Institut Blaise Pascal
28 * Universite Pierre et Marie Curie (Paris VI)
29 *
30 * from
31 *
32 * linux/fs/minix/dir.c
33 *
34 * Copyright (C) 1991, 1992 Linus Torvalds
35 *
36 * ext2 directory handling functions
37 *
38 * Big-endian to little-endian byte-swapping/bitmaps by
39 * David S. Miller (davem@caip.rutgers.edu), 1995
40 *
41 * All code that works with directory layout had been switched to pagecache
42 * and moved here. AV
43 */
44
45 #include <linux/pagemap.h>
46 #include "nilfs.h"
47 #include "page.h"
48
49 /*
50 * nilfs uses block-sized chunks. Arguably, sector-sized ones would be
51 * more robust, but we have what we have
52 */
53 static inline unsigned nilfs_chunk_size(struct inode *inode)
54 {
55 return inode->i_sb->s_blocksize;
56 }
57
58 static inline void nilfs_put_page(struct page *page)
59 {
60 kunmap(page);
61 page_cache_release(page);
62 }
63
64 static inline unsigned long dir_pages(struct inode *inode)
65 {
66 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
67 }
68
69 /*
70 * Return the offset into page `page_nr' of the last valid
71 * byte in that page, plus one.
72 */
73 static unsigned nilfs_last_byte(struct inode *inode, unsigned long page_nr)
74 {
75 unsigned last_byte = inode->i_size;
76
77 last_byte -= page_nr << PAGE_CACHE_SHIFT;
78 if (last_byte > PAGE_CACHE_SIZE)
79 last_byte = PAGE_CACHE_SIZE;
80 return last_byte;
81 }
82
83 static int nilfs_prepare_chunk(struct page *page, unsigned from, unsigned to)
84 {
85 loff_t pos = page_offset(page) + from;
86 return __block_write_begin(page, pos, to - from, nilfs_get_block);
87 }
88
89 static void nilfs_commit_chunk(struct page *page,
90 struct address_space *mapping,
91 unsigned from, unsigned to)
92 {
93 struct inode *dir = mapping->host;
94 loff_t pos = page_offset(page) + from;
95 unsigned len = to - from;
96 unsigned nr_dirty, copied;
97 int err;
98
99 nr_dirty = nilfs_page_count_clean_buffers(page, from, to);
100 copied = block_write_end(NULL, mapping, pos, len, len, page, NULL);
101 if (pos + copied > dir->i_size)
102 i_size_write(dir, pos + copied);
103 if (IS_DIRSYNC(dir))
104 nilfs_set_transaction_flag(NILFS_TI_SYNC);
105 err = nilfs_set_file_dirty(dir, nr_dirty);
106 WARN_ON(err); /* do not happen */
107 unlock_page(page);
108 }
109
110 static void nilfs_check_page(struct page *page)
111 {
112 struct inode *dir = page->mapping->host;
113 struct super_block *sb = dir->i_sb;
114 unsigned chunk_size = nilfs_chunk_size(dir);
115 char *kaddr = page_address(page);
116 unsigned offs, rec_len;
117 unsigned limit = PAGE_CACHE_SIZE;
118 struct nilfs_dir_entry *p;
119 char *error;
120
121 if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
122 limit = dir->i_size & ~PAGE_CACHE_MASK;
123 if (limit & (chunk_size - 1))
124 goto Ebadsize;
125 if (!limit)
126 goto out;
127 }
128 for (offs = 0; offs <= limit - NILFS_DIR_REC_LEN(1); offs += rec_len) {
129 p = (struct nilfs_dir_entry *)(kaddr + offs);
130 rec_len = nilfs_rec_len_from_disk(p->rec_len);
131
132 if (rec_len < NILFS_DIR_REC_LEN(1))
133 goto Eshort;
134 if (rec_len & 3)
135 goto Ealign;
136 if (rec_len < NILFS_DIR_REC_LEN(p->name_len))
137 goto Enamelen;
138 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
139 goto Espan;
140 }
141 if (offs != limit)
142 goto Eend;
143 out:
144 SetPageChecked(page);
145 return;
146
147 /* Too bad, we had an error */
148
149 Ebadsize:
150 nilfs_error(sb, "nilfs_check_page",
151 "size of directory #%lu is not a multiple of chunk size",
152 dir->i_ino
153 );
154 goto fail;
155 Eshort:
156 error = "rec_len is smaller than minimal";
157 goto bad_entry;
158 Ealign:
159 error = "unaligned directory entry";
160 goto bad_entry;
161 Enamelen:
162 error = "rec_len is too small for name_len";
163 goto bad_entry;
164 Espan:
165 error = "directory entry across blocks";
166 bad_entry:
167 nilfs_error(sb, "nilfs_check_page", "bad entry in directory #%lu: %s - "
168 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
169 dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
170 (unsigned long) le64_to_cpu(p->inode),
171 rec_len, p->name_len);
172 goto fail;
173 Eend:
174 p = (struct nilfs_dir_entry *)(kaddr + offs);
175 nilfs_error(sb, "nilfs_check_page",
176 "entry in directory #%lu spans the page boundary"
177 "offset=%lu, inode=%lu",
178 dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
179 (unsigned long) le64_to_cpu(p->inode));
180 fail:
181 SetPageChecked(page);
182 SetPageError(page);
183 }
184
185 static struct page *nilfs_get_page(struct inode *dir, unsigned long n)
186 {
187 struct address_space *mapping = dir->i_mapping;
188 struct page *page = read_mapping_page(mapping, n, NULL);
189
190 if (!IS_ERR(page)) {
191 kmap(page);
192 if (!PageChecked(page))
193 nilfs_check_page(page);
194 if (PageError(page))
195 goto fail;
196 }
197 return page;
198
199 fail:
200 nilfs_put_page(page);
201 return ERR_PTR(-EIO);
202 }
203
204 /*
205 * NOTE! unlike strncmp, nilfs_match returns 1 for success, 0 for failure.
206 *
207 * len <= NILFS_NAME_LEN and de != NULL are guaranteed by caller.
208 */
209 static int
210 nilfs_match(int len, const unsigned char *name, struct nilfs_dir_entry *de)
211 {
212 if (len != de->name_len)
213 return 0;
214 if (!de->inode)
215 return 0;
216 return !memcmp(name, de->name, len);
217 }
218
219 /*
220 * p is at least 6 bytes before the end of page
221 */
222 static struct nilfs_dir_entry *nilfs_next_entry(struct nilfs_dir_entry *p)
223 {
224 return (struct nilfs_dir_entry *)((char *)p +
225 nilfs_rec_len_from_disk(p->rec_len));
226 }
227
228 static unsigned char
229 nilfs_filetype_table[NILFS_FT_MAX] = {
230 [NILFS_FT_UNKNOWN] = DT_UNKNOWN,
231 [NILFS_FT_REG_FILE] = DT_REG,
232 [NILFS_FT_DIR] = DT_DIR,
233 [NILFS_FT_CHRDEV] = DT_CHR,
234 [NILFS_FT_BLKDEV] = DT_BLK,
235 [NILFS_FT_FIFO] = DT_FIFO,
236 [NILFS_FT_SOCK] = DT_SOCK,
237 [NILFS_FT_SYMLINK] = DT_LNK,
238 };
239
240 #define S_SHIFT 12
241 static unsigned char
242 nilfs_type_by_mode[S_IFMT >> S_SHIFT] = {
243 [S_IFREG >> S_SHIFT] = NILFS_FT_REG_FILE,
244 [S_IFDIR >> S_SHIFT] = NILFS_FT_DIR,
245 [S_IFCHR >> S_SHIFT] = NILFS_FT_CHRDEV,
246 [S_IFBLK >> S_SHIFT] = NILFS_FT_BLKDEV,
247 [S_IFIFO >> S_SHIFT] = NILFS_FT_FIFO,
248 [S_IFSOCK >> S_SHIFT] = NILFS_FT_SOCK,
249 [S_IFLNK >> S_SHIFT] = NILFS_FT_SYMLINK,
250 };
251
252 static void nilfs_set_de_type(struct nilfs_dir_entry *de, struct inode *inode)
253 {
254 umode_t mode = inode->i_mode;
255
256 de->file_type = nilfs_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
257 }
258
259 static int nilfs_readdir(struct file *file, struct dir_context *ctx)
260 {
261 loff_t pos = ctx->pos;
262 struct inode *inode = file_inode(file);
263 struct super_block *sb = inode->i_sb;
264 unsigned int offset = pos & ~PAGE_CACHE_MASK;
265 unsigned long n = pos >> PAGE_CACHE_SHIFT;
266 unsigned long npages = dir_pages(inode);
267 /* unsigned chunk_mask = ~(nilfs_chunk_size(inode)-1); */
268
269 if (pos > inode->i_size - NILFS_DIR_REC_LEN(1))
270 return 0;
271
272 for ( ; n < npages; n++, offset = 0) {
273 char *kaddr, *limit;
274 struct nilfs_dir_entry *de;
275 struct page *page = nilfs_get_page(inode, n);
276
277 if (IS_ERR(page)) {
278 nilfs_error(sb, __func__, "bad page in #%lu",
279 inode->i_ino);
280 ctx->pos += PAGE_CACHE_SIZE - offset;
281 return -EIO;
282 }
283 kaddr = page_address(page);
284 de = (struct nilfs_dir_entry *)(kaddr + offset);
285 limit = kaddr + nilfs_last_byte(inode, n) -
286 NILFS_DIR_REC_LEN(1);
287 for ( ; (char *)de <= limit; de = nilfs_next_entry(de)) {
288 if (de->rec_len == 0) {
289 nilfs_error(sb, __func__,
290 "zero-length directory entry");
291 nilfs_put_page(page);
292 return -EIO;
293 }
294 if (de->inode) {
295 unsigned char t;
296
297 if (de->file_type < NILFS_FT_MAX)
298 t = nilfs_filetype_table[de->file_type];
299 else
300 t = DT_UNKNOWN;
301
302 if (!dir_emit(ctx, de->name, de->name_len,
303 le64_to_cpu(de->inode), t)) {
304 nilfs_put_page(page);
305 return 0;
306 }
307 }
308 ctx->pos += nilfs_rec_len_from_disk(de->rec_len);
309 }
310 nilfs_put_page(page);
311 }
312 return 0;
313 }
314
315 /*
316 * nilfs_find_entry()
317 *
318 * finds an entry in the specified directory with the wanted name. It
319 * returns the page in which the entry was found, and the entry itself
320 * (as a parameter - res_dir). Page is returned mapped and unlocked.
321 * Entry is guaranteed to be valid.
322 */
323 struct nilfs_dir_entry *
324 nilfs_find_entry(struct inode *dir, const struct qstr *qstr,
325 struct page **res_page)
326 {
327 const unsigned char *name = qstr->name;
328 int namelen = qstr->len;
329 unsigned reclen = NILFS_DIR_REC_LEN(namelen);
330 unsigned long start, n;
331 unsigned long npages = dir_pages(dir);
332 struct page *page = NULL;
333 struct nilfs_inode_info *ei = NILFS_I(dir);
334 struct nilfs_dir_entry *de;
335
336 if (npages == 0)
337 goto out;
338
339 /* OFFSET_CACHE */
340 *res_page = NULL;
341
342 start = ei->i_dir_start_lookup;
343 if (start >= npages)
344 start = 0;
345 n = start;
346 do {
347 char *kaddr;
348 page = nilfs_get_page(dir, n);
349 if (!IS_ERR(page)) {
350 kaddr = page_address(page);
351 de = (struct nilfs_dir_entry *)kaddr;
352 kaddr += nilfs_last_byte(dir, n) - reclen;
353 while ((char *) de <= kaddr) {
354 if (de->rec_len == 0) {
355 nilfs_error(dir->i_sb, __func__,
356 "zero-length directory entry");
357 nilfs_put_page(page);
358 goto out;
359 }
360 if (nilfs_match(namelen, name, de))
361 goto found;
362 de = nilfs_next_entry(de);
363 }
364 nilfs_put_page(page);
365 }
366 if (++n >= npages)
367 n = 0;
368 /* next page is past the blocks we've got */
369 if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
370 nilfs_error(dir->i_sb, __func__,
371 "dir %lu size %lld exceeds block count %llu",
372 dir->i_ino, dir->i_size,
373 (unsigned long long)dir->i_blocks);
374 goto out;
375 }
376 } while (n != start);
377 out:
378 return NULL;
379
380 found:
381 *res_page = page;
382 ei->i_dir_start_lookup = n;
383 return de;
384 }
385
386 struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct page **p)
387 {
388 struct page *page = nilfs_get_page(dir, 0);
389 struct nilfs_dir_entry *de = NULL;
390
391 if (!IS_ERR(page)) {
392 de = nilfs_next_entry(
393 (struct nilfs_dir_entry *)page_address(page));
394 *p = page;
395 }
396 return de;
397 }
398
399 ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr)
400 {
401 ino_t res = 0;
402 struct nilfs_dir_entry *de;
403 struct page *page;
404
405 de = nilfs_find_entry(dir, qstr, &page);
406 if (de) {
407 res = le64_to_cpu(de->inode);
408 kunmap(page);
409 page_cache_release(page);
410 }
411 return res;
412 }
413
414 /* Releases the page */
415 void nilfs_set_link(struct inode *dir, struct nilfs_dir_entry *de,
416 struct page *page, struct inode *inode)
417 {
418 unsigned from = (char *) de - (char *) page_address(page);
419 unsigned to = from + nilfs_rec_len_from_disk(de->rec_len);
420 struct address_space *mapping = page->mapping;
421 int err;
422
423 lock_page(page);
424 err = nilfs_prepare_chunk(page, from, to);
425 BUG_ON(err);
426 de->inode = cpu_to_le64(inode->i_ino);
427 nilfs_set_de_type(de, inode);
428 nilfs_commit_chunk(page, mapping, from, to);
429 nilfs_put_page(page);
430 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
431 }
432
433 /*
434 * Parent is locked.
435 */
436 int nilfs_add_link(struct dentry *dentry, struct inode *inode)
437 {
438 struct inode *dir = dentry->d_parent->d_inode;
439 const unsigned char *name = dentry->d_name.name;
440 int namelen = dentry->d_name.len;
441 unsigned chunk_size = nilfs_chunk_size(dir);
442 unsigned reclen = NILFS_DIR_REC_LEN(namelen);
443 unsigned short rec_len, name_len;
444 struct page *page = NULL;
445 struct nilfs_dir_entry *de;
446 unsigned long npages = dir_pages(dir);
447 unsigned long n;
448 char *kaddr;
449 unsigned from, to;
450 int err;
451
452 /*
453 * We take care of directory expansion in the same loop.
454 * This code plays outside i_size, so it locks the page
455 * to protect that region.
456 */
457 for (n = 0; n <= npages; n++) {
458 char *dir_end;
459
460 page = nilfs_get_page(dir, n);
461 err = PTR_ERR(page);
462 if (IS_ERR(page))
463 goto out;
464 lock_page(page);
465 kaddr = page_address(page);
466 dir_end = kaddr + nilfs_last_byte(dir, n);
467 de = (struct nilfs_dir_entry *)kaddr;
468 kaddr += PAGE_CACHE_SIZE - reclen;
469 while ((char *)de <= kaddr) {
470 if ((char *)de == dir_end) {
471 /* We hit i_size */
472 name_len = 0;
473 rec_len = chunk_size;
474 de->rec_len = nilfs_rec_len_to_disk(chunk_size);
475 de->inode = 0;
476 goto got_it;
477 }
478 if (de->rec_len == 0) {
479 nilfs_error(dir->i_sb, __func__,
480 "zero-length directory entry");
481 err = -EIO;
482 goto out_unlock;
483 }
484 err = -EEXIST;
485 if (nilfs_match(namelen, name, de))
486 goto out_unlock;
487 name_len = NILFS_DIR_REC_LEN(de->name_len);
488 rec_len = nilfs_rec_len_from_disk(de->rec_len);
489 if (!de->inode && rec_len >= reclen)
490 goto got_it;
491 if (rec_len >= name_len + reclen)
492 goto got_it;
493 de = (struct nilfs_dir_entry *)((char *)de + rec_len);
494 }
495 unlock_page(page);
496 nilfs_put_page(page);
497 }
498 BUG();
499 return -EINVAL;
500
501 got_it:
502 from = (char *)de - (char *)page_address(page);
503 to = from + rec_len;
504 err = nilfs_prepare_chunk(page, from, to);
505 if (err)
506 goto out_unlock;
507 if (de->inode) {
508 struct nilfs_dir_entry *de1;
509
510 de1 = (struct nilfs_dir_entry *)((char *)de + name_len);
511 de1->rec_len = nilfs_rec_len_to_disk(rec_len - name_len);
512 de->rec_len = nilfs_rec_len_to_disk(name_len);
513 de = de1;
514 }
515 de->name_len = namelen;
516 memcpy(de->name, name, namelen);
517 de->inode = cpu_to_le64(inode->i_ino);
518 nilfs_set_de_type(de, inode);
519 nilfs_commit_chunk(page, page->mapping, from, to);
520 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
521 nilfs_mark_inode_dirty(dir);
522 /* OFFSET_CACHE */
523 out_put:
524 nilfs_put_page(page);
525 out:
526 return err;
527 out_unlock:
528 unlock_page(page);
529 goto out_put;
530 }
531
532 /*
533 * nilfs_delete_entry deletes a directory entry by merging it with the
534 * previous entry. Page is up-to-date. Releases the page.
535 */
536 int nilfs_delete_entry(struct nilfs_dir_entry *dir, struct page *page)
537 {
538 struct address_space *mapping = page->mapping;
539 struct inode *inode = mapping->host;
540 char *kaddr = page_address(page);
541 unsigned from = ((char *)dir - kaddr) & ~(nilfs_chunk_size(inode) - 1);
542 unsigned to = ((char *)dir - kaddr) +
543 nilfs_rec_len_from_disk(dir->rec_len);
544 struct nilfs_dir_entry *pde = NULL;
545 struct nilfs_dir_entry *de = (struct nilfs_dir_entry *)(kaddr + from);
546 int err;
547
548 while ((char *)de < (char *)dir) {
549 if (de->rec_len == 0) {
550 nilfs_error(inode->i_sb, __func__,
551 "zero-length directory entry");
552 err = -EIO;
553 goto out;
554 }
555 pde = de;
556 de = nilfs_next_entry(de);
557 }
558 if (pde)
559 from = (char *)pde - (char *)page_address(page);
560 lock_page(page);
561 err = nilfs_prepare_chunk(page, from, to);
562 BUG_ON(err);
563 if (pde)
564 pde->rec_len = nilfs_rec_len_to_disk(to - from);
565 dir->inode = 0;
566 nilfs_commit_chunk(page, mapping, from, to);
567 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
568 out:
569 nilfs_put_page(page);
570 return err;
571 }
572
573 /*
574 * Set the first fragment of directory.
575 */
576 int nilfs_make_empty(struct inode *inode, struct inode *parent)
577 {
578 struct address_space *mapping = inode->i_mapping;
579 struct page *page = grab_cache_page(mapping, 0);
580 unsigned chunk_size = nilfs_chunk_size(inode);
581 struct nilfs_dir_entry *de;
582 int err;
583 void *kaddr;
584
585 if (!page)
586 return -ENOMEM;
587
588 err = nilfs_prepare_chunk(page, 0, chunk_size);
589 if (unlikely(err)) {
590 unlock_page(page);
591 goto fail;
592 }
593 kaddr = kmap_atomic(page);
594 memset(kaddr, 0, chunk_size);
595 de = (struct nilfs_dir_entry *)kaddr;
596 de->name_len = 1;
597 de->rec_len = nilfs_rec_len_to_disk(NILFS_DIR_REC_LEN(1));
598 memcpy(de->name, ".\0\0", 4);
599 de->inode = cpu_to_le64(inode->i_ino);
600 nilfs_set_de_type(de, inode);
601
602 de = (struct nilfs_dir_entry *)(kaddr + NILFS_DIR_REC_LEN(1));
603 de->name_len = 2;
604 de->rec_len = nilfs_rec_len_to_disk(chunk_size - NILFS_DIR_REC_LEN(1));
605 de->inode = cpu_to_le64(parent->i_ino);
606 memcpy(de->name, "..\0", 4);
607 nilfs_set_de_type(de, inode);
608 kunmap_atomic(kaddr);
609 nilfs_commit_chunk(page, mapping, 0, chunk_size);
610 fail:
611 page_cache_release(page);
612 return err;
613 }
614
615 /*
616 * routine to check that the specified directory is empty (for rmdir)
617 */
618 int nilfs_empty_dir(struct inode *inode)
619 {
620 struct page *page = NULL;
621 unsigned long i, npages = dir_pages(inode);
622
623 for (i = 0; i < npages; i++) {
624 char *kaddr;
625 struct nilfs_dir_entry *de;
626
627 page = nilfs_get_page(inode, i);
628 if (IS_ERR(page))
629 continue;
630
631 kaddr = page_address(page);
632 de = (struct nilfs_dir_entry *)kaddr;
633 kaddr += nilfs_last_byte(inode, i) - NILFS_DIR_REC_LEN(1);
634
635 while ((char *)de <= kaddr) {
636 if (de->rec_len == 0) {
637 nilfs_error(inode->i_sb, __func__,
638 "zero-length directory entry "
639 "(kaddr=%p, de=%p)\n", kaddr, de);
640 goto not_empty;
641 }
642 if (de->inode != 0) {
643 /* check for . and .. */
644 if (de->name[0] != '.')
645 goto not_empty;
646 if (de->name_len > 2)
647 goto not_empty;
648 if (de->name_len < 2) {
649 if (de->inode !=
650 cpu_to_le64(inode->i_ino))
651 goto not_empty;
652 } else if (de->name[1] != '.')
653 goto not_empty;
654 }
655 de = nilfs_next_entry(de);
656 }
657 nilfs_put_page(page);
658 }
659 return 1;
660
661 not_empty:
662 nilfs_put_page(page);
663 return 0;
664 }
665
666 const struct file_operations nilfs_dir_operations = {
667 .llseek = generic_file_llseek,
668 .read = generic_read_dir,
669 .iterate = nilfs_readdir,
670 .unlocked_ioctl = nilfs_ioctl,
671 #ifdef CONFIG_COMPAT
672 .compat_ioctl = nilfs_compat_ioctl,
673 #endif /* CONFIG_COMPAT */
674 .fsync = nilfs_sync_file,
675
676 };
Linux with added FPC-III support