blob: b3dbd716cd3a19b537c87b88048cd54ee43d7e50 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/ext2/dir.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * from
10 *
11 * linux/fs/minix/dir.c
12 *
13 * Copyright (C) 1991, 1992 Linus Torvalds
14 *
15 * ext2 directory handling functions
16 *
17 * Big-endian to little-endian byte-swapping/bitmaps by
18 * David S. Miller (davem@caip.rutgers.edu), 1995
19 *
20 * All code that works with directory layout had been switched to pagecache
21 * and moved here. AV
22 */
23
24#include "ext2.h"
25#include <linux/pagemap.h>
26#include <linux/smp_lock.h>
27
28typedef struct ext2_dir_entry_2 ext2_dirent;
29
30/*
31 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
32 * more robust, but we have what we have
33 */
34static inline unsigned ext2_chunk_size(struct inode *inode)
35{
36 return inode->i_sb->s_blocksize;
37}
38
39static inline void ext2_put_page(struct page *page)
40{
41 kunmap(page);
42 page_cache_release(page);
43}
44
45static inline unsigned long dir_pages(struct inode *inode)
46{
47 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
48}
49
50/*
51 * Return the offset into page `page_nr' of the last valid
52 * byte in that page, plus one.
53 */
54static unsigned
55ext2_last_byte(struct inode *inode, unsigned long page_nr)
56{
57 unsigned last_byte = inode->i_size;
58
59 last_byte -= page_nr << PAGE_CACHE_SHIFT;
60 if (last_byte > PAGE_CACHE_SIZE)
61 last_byte = PAGE_CACHE_SIZE;
62 return last_byte;
63}
64
65static int ext2_commit_chunk(struct page *page, unsigned from, unsigned to)
66{
67 struct inode *dir = page->mapping->host;
68 int err = 0;
69 dir->i_version++;
70 page->mapping->a_ops->commit_write(NULL, page, from, to);
71 if (IS_DIRSYNC(dir))
72 err = write_one_page(page, 1);
73 else
74 unlock_page(page);
75 return err;
76}
77
78static void ext2_check_page(struct page *page)
79{
80 struct inode *dir = page->mapping->host;
81 struct super_block *sb = dir->i_sb;
82 unsigned chunk_size = ext2_chunk_size(dir);
83 char *kaddr = page_address(page);
84 u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
85 unsigned offs, rec_len;
86 unsigned limit = PAGE_CACHE_SIZE;
87 ext2_dirent *p;
88 char *error;
89
90 if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
91 limit = dir->i_size & ~PAGE_CACHE_MASK;
92 if (limit & (chunk_size - 1))
93 goto Ebadsize;
94 if (!limit)
95 goto out;
96 }
97 for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
98 p = (ext2_dirent *)(kaddr + offs);
99 rec_len = le16_to_cpu(p->rec_len);
100
101 if (rec_len < EXT2_DIR_REC_LEN(1))
102 goto Eshort;
103 if (rec_len & 3)
104 goto Ealign;
105 if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
106 goto Enamelen;
107 if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
108 goto Espan;
109 if (le32_to_cpu(p->inode) > max_inumber)
110 goto Einumber;
111 }
112 if (offs != limit)
113 goto Eend;
114out:
115 SetPageChecked(page);
116 return;
117
118 /* Too bad, we had an error */
119
120Ebadsize:
121 ext2_error(sb, "ext2_check_page",
122 "size of directory #%lu is not a multiple of chunk size",
123 dir->i_ino
124 );
125 goto fail;
126Eshort:
127 error = "rec_len is smaller than minimal";
128 goto bad_entry;
129Ealign:
130 error = "unaligned directory entry";
131 goto bad_entry;
132Enamelen:
133 error = "rec_len is too small for name_len";
134 goto bad_entry;
135Espan:
136 error = "directory entry across blocks";
137 goto bad_entry;
138Einumber:
139 error = "inode out of bounds";
140bad_entry:
141 ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
142 "offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
143 dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
144 (unsigned long) le32_to_cpu(p->inode),
145 rec_len, p->name_len);
146 goto fail;
147Eend:
148 p = (ext2_dirent *)(kaddr + offs);
149 ext2_error (sb, "ext2_check_page",
150 "entry in directory #%lu spans the page boundary"
151 "offset=%lu, inode=%lu",
152 dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
153 (unsigned long) le32_to_cpu(p->inode));
154fail:
155 SetPageChecked(page);
156 SetPageError(page);
157}
158
159static struct page * ext2_get_page(struct inode *dir, unsigned long n)
160{
161 struct address_space *mapping = dir->i_mapping;
162 struct page *page = read_cache_page(mapping, n,
163 (filler_t*)mapping->a_ops->readpage, NULL);
164 if (!IS_ERR(page)) {
165 wait_on_page_locked(page);
166 kmap(page);
167 if (!PageUptodate(page))
168 goto fail;
169 if (!PageChecked(page))
170 ext2_check_page(page);
171 if (PageError(page))
172 goto fail;
173 }
174 return page;
175
176fail:
177 ext2_put_page(page);
178 return ERR_PTR(-EIO);
179}
180
181/*
182 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
183 *
184 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
185 */
186static inline int ext2_match (int len, const char * const name,
187 struct ext2_dir_entry_2 * de)
188{
189 if (len != de->name_len)
190 return 0;
191 if (!de->inode)
192 return 0;
193 return !memcmp(name, de->name, len);
194}
195
196/*
197 * p is at least 6 bytes before the end of page
198 */
199static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
200{
201 return (ext2_dirent *)((char*)p + le16_to_cpu(p->rec_len));
202}
203
204static inline unsigned
205ext2_validate_entry(char *base, unsigned offset, unsigned mask)
206{
207 ext2_dirent *de = (ext2_dirent*)(base + offset);
208 ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
209 while ((char*)p < (char*)de) {
210 if (p->rec_len == 0)
211 break;
212 p = ext2_next_entry(p);
213 }
214 return (char *)p - base;
215}
216
217static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
218 [EXT2_FT_UNKNOWN] = DT_UNKNOWN,
219 [EXT2_FT_REG_FILE] = DT_REG,
220 [EXT2_FT_DIR] = DT_DIR,
221 [EXT2_FT_CHRDEV] = DT_CHR,
222 [EXT2_FT_BLKDEV] = DT_BLK,
223 [EXT2_FT_FIFO] = DT_FIFO,
224 [EXT2_FT_SOCK] = DT_SOCK,
225 [EXT2_FT_SYMLINK] = DT_LNK,
226};
227
228#define S_SHIFT 12
229static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
230 [S_IFREG >> S_SHIFT] = EXT2_FT_REG_FILE,
231 [S_IFDIR >> S_SHIFT] = EXT2_FT_DIR,
232 [S_IFCHR >> S_SHIFT] = EXT2_FT_CHRDEV,
233 [S_IFBLK >> S_SHIFT] = EXT2_FT_BLKDEV,
234 [S_IFIFO >> S_SHIFT] = EXT2_FT_FIFO,
235 [S_IFSOCK >> S_SHIFT] = EXT2_FT_SOCK,
236 [S_IFLNK >> S_SHIFT] = EXT2_FT_SYMLINK,
237};
238
239static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
240{
241 mode_t mode = inode->i_mode;
242 if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
243 de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
244 else
245 de->file_type = 0;
246}
247
248static int
249ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
250{
251 loff_t pos = filp->f_pos;
252 struct inode *inode = filp->f_dentry->d_inode;
253 struct super_block *sb = inode->i_sb;
254 unsigned int offset = pos & ~PAGE_CACHE_MASK;
255 unsigned long n = pos >> PAGE_CACHE_SHIFT;
256 unsigned long npages = dir_pages(inode);
257 unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
258 unsigned char *types = NULL;
Al Viro2d7f2ea2006-03-15 21:41:59 +0000259 int need_revalidate = filp->f_version != inode->i_version;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260
261 if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
Al Viro2d7f2ea2006-03-15 21:41:59 +0000262 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700263
264 if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
265 types = ext2_filetype_table;
266
267 for ( ; n < npages; n++, offset = 0) {
268 char *kaddr, *limit;
269 ext2_dirent *de;
270 struct page *page = ext2_get_page(inode, n);
271
272 if (IS_ERR(page)) {
273 ext2_error(sb, __FUNCTION__,
274 "bad page in #%lu",
275 inode->i_ino);
276 filp->f_pos += PAGE_CACHE_SIZE - offset;
Al Viro2d7f2ea2006-03-15 21:41:59 +0000277 return -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 }
279 kaddr = page_address(page);
Al Viro2d7f2ea2006-03-15 21:41:59 +0000280 if (unlikely(need_revalidate)) {
281 if (offset) {
282 offset = ext2_validate_entry(kaddr, offset, chunk_mask);
283 filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
284 }
285 filp->f_version = inode->i_version;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 need_revalidate = 0;
287 }
288 de = (ext2_dirent *)(kaddr+offset);
289 limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
290 for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
291 if (de->rec_len == 0) {
292 ext2_error(sb, __FUNCTION__,
293 "zero-length directory entry");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 ext2_put_page(page);
Al Viro2d7f2ea2006-03-15 21:41:59 +0000295 return -EIO;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 }
297 if (de->inode) {
298 int over;
299 unsigned char d_type = DT_UNKNOWN;
300
301 if (types && de->file_type < EXT2_FT_MAX)
302 d_type = types[de->file_type];
303
304 offset = (char *)de - kaddr;
305 over = filldir(dirent, de->name, de->name_len,
306 (n<<PAGE_CACHE_SHIFT) | offset,
307 le32_to_cpu(de->inode), d_type);
308 if (over) {
309 ext2_put_page(page);
Al Viro2d7f2ea2006-03-15 21:41:59 +0000310 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700311 }
312 }
313 filp->f_pos += le16_to_cpu(de->rec_len);
314 }
315 ext2_put_page(page);
316 }
Al Viro2d7f2ea2006-03-15 21:41:59 +0000317 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318}
319
320/*
321 * ext2_find_entry()
322 *
323 * finds an entry in the specified directory with the wanted name. It
324 * returns the page in which the entry was found, and the entry itself
325 * (as a parameter - res_dir). Page is returned mapped and unlocked.
326 * Entry is guaranteed to be valid.
327 */
328struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
329 struct dentry *dentry, struct page ** res_page)
330{
331 const char *name = dentry->d_name.name;
332 int namelen = dentry->d_name.len;
333 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
334 unsigned long start, n;
335 unsigned long npages = dir_pages(dir);
336 struct page *page = NULL;
337 struct ext2_inode_info *ei = EXT2_I(dir);
338 ext2_dirent * de;
339
340 if (npages == 0)
341 goto out;
342
343 /* OFFSET_CACHE */
344 *res_page = NULL;
345
346 start = ei->i_dir_start_lookup;
347 if (start >= npages)
348 start = 0;
349 n = start;
350 do {
351 char *kaddr;
352 page = ext2_get_page(dir, n);
353 if (!IS_ERR(page)) {
354 kaddr = page_address(page);
355 de = (ext2_dirent *) kaddr;
356 kaddr += ext2_last_byte(dir, n) - reclen;
357 while ((char *) de <= kaddr) {
358 if (de->rec_len == 0) {
359 ext2_error(dir->i_sb, __FUNCTION__,
360 "zero-length directory entry");
361 ext2_put_page(page);
362 goto out;
363 }
364 if (ext2_match (namelen, name, de))
365 goto found;
366 de = ext2_next_entry(de);
367 }
368 ext2_put_page(page);
369 }
370 if (++n >= npages)
371 n = 0;
372 } while (n != start);
373out:
374 return NULL;
375
376found:
377 *res_page = page;
378 ei->i_dir_start_lookup = n;
379 return de;
380}
381
382struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
383{
384 struct page *page = ext2_get_page(dir, 0);
385 ext2_dirent *de = NULL;
386
387 if (!IS_ERR(page)) {
388 de = ext2_next_entry((ext2_dirent *) page_address(page));
389 *p = page;
390 }
391 return de;
392}
393
394ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
395{
396 ino_t res = 0;
397 struct ext2_dir_entry_2 * de;
398 struct page *page;
399
400 de = ext2_find_entry (dir, dentry, &page);
401 if (de) {
402 res = le32_to_cpu(de->inode);
403 kunmap(page);
404 page_cache_release(page);
405 }
406 return res;
407}
408
409/* Releases the page */
410void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
411 struct page *page, struct inode *inode)
412{
413 unsigned from = (char *) de - (char *) page_address(page);
414 unsigned to = from + le16_to_cpu(de->rec_len);
415 int err;
416
417 lock_page(page);
418 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
419 if (err)
420 BUG();
421 de->inode = cpu_to_le32(inode->i_ino);
422 ext2_set_de_type (de, inode);
423 err = ext2_commit_chunk(page, from, to);
424 ext2_put_page(page);
425 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
426 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
427 mark_inode_dirty(dir);
428}
429
430/*
431 * Parent is locked.
432 */
433int ext2_add_link (struct dentry *dentry, struct inode *inode)
434{
435 struct inode *dir = dentry->d_parent->d_inode;
436 const char *name = dentry->d_name.name;
437 int namelen = dentry->d_name.len;
438 unsigned chunk_size = ext2_chunk_size(dir);
439 unsigned reclen = EXT2_DIR_REC_LEN(namelen);
440 unsigned short rec_len, name_len;
441 struct page *page = NULL;
442 ext2_dirent * de;
443 unsigned long npages = dir_pages(dir);
444 unsigned long n;
445 char *kaddr;
446 unsigned from, to;
447 int err;
448
449 /*
450 * We take care of directory expansion in the same loop.
451 * This code plays outside i_size, so it locks the page
452 * to protect that region.
453 */
454 for (n = 0; n <= npages; n++) {
455 char *dir_end;
456
457 page = ext2_get_page(dir, n);
458 err = PTR_ERR(page);
459 if (IS_ERR(page))
460 goto out;
461 lock_page(page);
462 kaddr = page_address(page);
463 dir_end = kaddr + ext2_last_byte(dir, n);
464 de = (ext2_dirent *)kaddr;
465 kaddr += PAGE_CACHE_SIZE - reclen;
466 while ((char *)de <= kaddr) {
467 if ((char *)de == dir_end) {
468 /* We hit i_size */
469 name_len = 0;
470 rec_len = chunk_size;
471 de->rec_len = cpu_to_le16(chunk_size);
472 de->inode = 0;
473 goto got_it;
474 }
475 if (de->rec_len == 0) {
476 ext2_error(dir->i_sb, __FUNCTION__,
477 "zero-length directory entry");
478 err = -EIO;
479 goto out_unlock;
480 }
481 err = -EEXIST;
482 if (ext2_match (namelen, name, de))
483 goto out_unlock;
484 name_len = EXT2_DIR_REC_LEN(de->name_len);
485 rec_len = le16_to_cpu(de->rec_len);
486 if (!de->inode && rec_len >= reclen)
487 goto got_it;
488 if (rec_len >= name_len + reclen)
489 goto got_it;
490 de = (ext2_dirent *) ((char *) de + rec_len);
491 }
492 unlock_page(page);
493 ext2_put_page(page);
494 }
495 BUG();
496 return -EINVAL;
497
498got_it:
499 from = (char*)de - (char*)page_address(page);
500 to = from + rec_len;
501 err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
502 if (err)
503 goto out_unlock;
504 if (de->inode) {
505 ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
506 de1->rec_len = cpu_to_le16(rec_len - name_len);
507 de->rec_len = cpu_to_le16(name_len);
508 de = de1;
509 }
510 de->name_len = namelen;
511 memcpy (de->name, name, namelen);
512 de->inode = cpu_to_le32(inode->i_ino);
513 ext2_set_de_type (de, inode);
514 err = ext2_commit_chunk(page, from, to);
515 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
516 EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
517 mark_inode_dirty(dir);
518 /* OFFSET_CACHE */
519out_put:
520 ext2_put_page(page);
521out:
522 return err;
523out_unlock:
524 unlock_page(page);
525 goto out_put;
526}
527
528/*
529 * ext2_delete_entry deletes a directory entry by merging it with the
530 * previous entry. Page is up-to-date. Releases the page.
531 */
532int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
533{
534 struct address_space *mapping = page->mapping;
535 struct inode *inode = mapping->host;
536 char *kaddr = page_address(page);
537 unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
538 unsigned to = ((char*)dir - kaddr) + le16_to_cpu(dir->rec_len);
539 ext2_dirent * pde = NULL;
540 ext2_dirent * de = (ext2_dirent *) (kaddr + from);
541 int err;
542
543 while ((char*)de < (char*)dir) {
544 if (de->rec_len == 0) {
545 ext2_error(inode->i_sb, __FUNCTION__,
546 "zero-length directory entry");
547 err = -EIO;
548 goto out;
549 }
550 pde = de;
551 de = ext2_next_entry(de);
552 }
553 if (pde)
554 from = (char*)pde - (char*)page_address(page);
555 lock_page(page);
556 err = mapping->a_ops->prepare_write(NULL, page, from, to);
557 if (err)
558 BUG();
559 if (pde)
560 pde->rec_len = cpu_to_le16(to-from);
561 dir->inode = 0;
562 err = ext2_commit_chunk(page, from, to);
563 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
564 EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
565 mark_inode_dirty(inode);
566out:
567 ext2_put_page(page);
568 return err;
569}
570
571/*
572 * Set the first fragment of directory.
573 */
574int ext2_make_empty(struct inode *inode, struct inode *parent)
575{
576 struct address_space *mapping = inode->i_mapping;
577 struct page *page = grab_cache_page(mapping, 0);
578 unsigned chunk_size = ext2_chunk_size(inode);
579 struct ext2_dir_entry_2 * de;
580 int err;
581 void *kaddr;
582
583 if (!page)
584 return -ENOMEM;
585 err = mapping->a_ops->prepare_write(NULL, page, 0, chunk_size);
586 if (err) {
587 unlock_page(page);
588 goto fail;
589 }
590 kaddr = kmap_atomic(page, KM_USER0);
Luiz Fernando Capitulino7823c7c2006-01-11 01:38:27 +0100591 memset(kaddr, 0, chunk_size);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592 de = (struct ext2_dir_entry_2 *)kaddr;
593 de->name_len = 1;
594 de->rec_len = cpu_to_le16(EXT2_DIR_REC_LEN(1));
595 memcpy (de->name, ".\0\0", 4);
596 de->inode = cpu_to_le32(inode->i_ino);
597 ext2_set_de_type (de, inode);
598
599 de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
600 de->name_len = 2;
601 de->rec_len = cpu_to_le16(chunk_size - EXT2_DIR_REC_LEN(1));
602 de->inode = cpu_to_le32(parent->i_ino);
603 memcpy (de->name, "..\0", 4);
604 ext2_set_de_type (de, inode);
605 kunmap_atomic(kaddr, KM_USER0);
606 err = ext2_commit_chunk(page, 0, chunk_size);
607fail:
608 page_cache_release(page);
609 return err;
610}
611
612/*
613 * routine to check that the specified directory is empty (for rmdir)
614 */
615int ext2_empty_dir (struct inode * inode)
616{
617 struct page *page = NULL;
618 unsigned long i, npages = dir_pages(inode);
619
620 for (i = 0; i < npages; i++) {
621 char *kaddr;
622 ext2_dirent * de;
623 page = ext2_get_page(inode, i);
624
625 if (IS_ERR(page))
626 continue;
627
628 kaddr = page_address(page);
629 de = (ext2_dirent *)kaddr;
630 kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);
631
632 while ((char *)de <= kaddr) {
633 if (de->rec_len == 0) {
634 ext2_error(inode->i_sb, __FUNCTION__,
635 "zero-length directory entry");
636 printk("kaddr=%p, de=%p\n", kaddr, de);
637 goto not_empty;
638 }
639 if (de->inode != 0) {
640 /* check for . and .. */
641 if (de->name[0] != '.')
642 goto not_empty;
643 if (de->name_len > 2)
644 goto not_empty;
645 if (de->name_len < 2) {
646 if (de->inode !=
647 cpu_to_le32(inode->i_ino))
648 goto not_empty;
649 } else if (de->name[1] != '.')
650 goto not_empty;
651 }
652 de = ext2_next_entry(de);
653 }
654 ext2_put_page(page);
655 }
656 return 1;
657
658not_empty:
659 ext2_put_page(page);
660 return 0;
661}
662
663struct file_operations ext2_dir_operations = {
664 .llseek = generic_file_llseek,
665 .read = generic_read_dir,
666 .readdir = ext2_readdir,
667 .ioctl = ext2_ioctl,
668 .fsync = ext2_sync_file,
669};