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dir.c
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1 /*
2  * Copyright (C) 2005, 2006
3  * Avishay Traeger ([email protected])
4  * Copyright (C) 2008, 2009
5  * Boaz Harrosh <[email protected]>
6  *
7  * Copyrights for code taken from ext2:
8  * Copyright (C) 1992, 1993, 1994, 1995
9  * Remy Card ([email protected])
10  * Laboratoire MASI - Institut Blaise Pascal
11  * Universite Pierre et Marie Curie (Paris VI)
12  * from
13  * linux/fs/minix/inode.c
14  * Copyright (C) 1991, 1992 Linus Torvalds
15  *
16  * This file is part of exofs.
17  *
18  * exofs is free software; you can redistribute it and/or modify
19  * it under the terms of the GNU General Public License as published by
20  * the Free Software Foundation. Since it is based on ext2, and the only
21  * valid version of GPL for the Linux kernel is version 2, the only valid
22  * version of GPL for exofs is version 2.
23  *
24  * exofs is distributed in the hope that it will be useful,
25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27  * GNU General Public License for more details.
28  *
29  * You should have received a copy of the GNU General Public License
30  * along with exofs; if not, write to the Free Software
31  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
32  */
33 
34 #include "exofs.h"
35 
36 static inline unsigned exofs_chunk_size(struct inode *inode)
37 {
38  return inode->i_sb->s_blocksize;
39 }
40 
41 static inline void exofs_put_page(struct page *page)
42 {
43  kunmap(page);
44  page_cache_release(page);
45 }
46 
47 /* Accesses dir's inode->i_size must be called under inode lock */
48 static inline unsigned long dir_pages(struct inode *inode)
49 {
50  return (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
51 }
52 
53 static unsigned exofs_last_byte(struct inode *inode, unsigned long page_nr)
54 {
55  loff_t last_byte = inode->i_size;
56 
57  last_byte -= page_nr << PAGE_CACHE_SHIFT;
58  if (last_byte > PAGE_CACHE_SIZE)
59  last_byte = PAGE_CACHE_SIZE;
60  return last_byte;
61 }
62 
63 static int exofs_commit_chunk(struct page *page, loff_t pos, unsigned len)
64 {
65  struct address_space *mapping = page->mapping;
66  struct inode *dir = mapping->host;
67  int err = 0;
68 
69  dir->i_version++;
70 
71  if (!PageUptodate(page))
72  SetPageUptodate(page);
73 
74  if (pos+len > dir->i_size) {
75  i_size_write(dir, pos+len);
76  mark_inode_dirty(dir);
77  }
78  set_page_dirty(page);
79 
80  if (IS_DIRSYNC(dir))
81  err = write_one_page(page, 1);
82  else
83  unlock_page(page);
84 
85  return err;
86 }
87 
88 static void exofs_check_page(struct page *page)
89 {
90  struct inode *dir = page->mapping->host;
91  unsigned chunk_size = exofs_chunk_size(dir);
92  char *kaddr = page_address(page);
93  unsigned offs, rec_len;
94  unsigned limit = PAGE_CACHE_SIZE;
95  struct exofs_dir_entry *p;
96  char *error;
97 
98  /* if the page is the last one in the directory */
99  if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
100  limit = dir->i_size & ~PAGE_CACHE_MASK;
101  if (limit & (chunk_size - 1))
102  goto Ebadsize;
103  if (!limit)
104  goto out;
105  }
106  for (offs = 0; offs <= limit - EXOFS_DIR_REC_LEN(1); offs += rec_len) {
107  p = (struct exofs_dir_entry *)(kaddr + offs);
108  rec_len = le16_to_cpu(p->rec_len);
109 
110  if (rec_len < EXOFS_DIR_REC_LEN(1))
111  goto Eshort;
112  if (rec_len & 3)
113  goto Ealign;
114  if (rec_len < EXOFS_DIR_REC_LEN(p->name_len))
115  goto Enamelen;
116  if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
117  goto Espan;
118  }
119  if (offs != limit)
120  goto Eend;
121 out:
122  SetPageChecked(page);
123  return;
124 
125 Ebadsize:
126  EXOFS_ERR("ERROR [exofs_check_page]: "
127  "size of directory(0x%lx) is not a multiple of chunk size\n",
128  dir->i_ino
129  );
130  goto fail;
131 Eshort:
132  error = "rec_len is smaller than minimal";
133  goto bad_entry;
134 Ealign:
135  error = "unaligned directory entry";
136  goto bad_entry;
137 Enamelen:
138  error = "rec_len is too small for name_len";
139  goto bad_entry;
140 Espan:
141  error = "directory entry across blocks";
142  goto bad_entry;
143 bad_entry:
144  EXOFS_ERR(
145  "ERROR [exofs_check_page]: bad entry in directory(0x%lx): %s - "
146  "offset=%lu, inode=0x%llu, rec_len=%d, name_len=%d\n",
147  dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
149  rec_len, p->name_len);
150  goto fail;
151 Eend:
152  p = (struct exofs_dir_entry *)(kaddr + offs);
153  EXOFS_ERR("ERROR [exofs_check_page]: "
154  "entry in directory(0x%lx) spans the page boundary"
155  "offset=%lu, inode=0x%llx\n",
156  dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
157  _LLU(le64_to_cpu(p->inode_no)));
158 fail:
159  SetPageChecked(page);
160  SetPageError(page);
161 }
162 
163 static struct page *exofs_get_page(struct inode *dir, unsigned long n)
164 {
165  struct address_space *mapping = dir->i_mapping;
166  struct page *page = read_mapping_page(mapping, n, NULL);
167 
168  if (!IS_ERR(page)) {
169  kmap(page);
170  if (!PageChecked(page))
171  exofs_check_page(page);
172  if (PageError(page))
173  goto fail;
174  }
175  return page;
176 
177 fail:
178  exofs_put_page(page);
179  return ERR_PTR(-EIO);
180 }
181 
182 static inline int exofs_match(int len, const unsigned char *name,
183  struct exofs_dir_entry *de)
184 {
185  if (len != de->name_len)
186  return 0;
187  if (!de->inode_no)
188  return 0;
189  return !memcmp(name, de->name, len);
190 }
191 
192 static inline
193 struct exofs_dir_entry *exofs_next_entry(struct exofs_dir_entry *p)
194 {
195  return (struct exofs_dir_entry *)((char *)p + le16_to_cpu(p->rec_len));
196 }
197 
198 static inline unsigned
199 exofs_validate_entry(char *base, unsigned offset, unsigned mask)
200 {
201  struct exofs_dir_entry *de = (struct exofs_dir_entry *)(base + offset);
202  struct exofs_dir_entry *p =
203  (struct exofs_dir_entry *)(base + (offset&mask));
204  while ((char *)p < (char *)de) {
205  if (p->rec_len == 0)
206  break;
207  p = exofs_next_entry(p);
208  }
209  return (char *)p - base;
210 }
211 
212 static unsigned char exofs_filetype_table[EXOFS_FT_MAX] = {
215  [EXOFS_FT_DIR] = DT_DIR,
221 };
222 
223 #define S_SHIFT 12
224 static unsigned char exofs_type_by_mode[S_IFMT >> S_SHIFT] = {
232 };
233 
234 static inline
235 void exofs_set_de_type(struct exofs_dir_entry *de, struct inode *inode)
236 {
237  umode_t mode = inode->i_mode;
238  de->file_type = exofs_type_by_mode[(mode & S_IFMT) >> S_SHIFT];
239 }
240 
241 static int
242 exofs_readdir(struct file *filp, void *dirent, filldir_t filldir)
243 {
244  loff_t pos = filp->f_pos;
245  struct inode *inode = filp->f_path.dentry->d_inode;
246  unsigned int offset = pos & ~PAGE_CACHE_MASK;
247  unsigned long n = pos >> PAGE_CACHE_SHIFT;
248  unsigned long npages = dir_pages(inode);
249  unsigned chunk_mask = ~(exofs_chunk_size(inode)-1);
250  unsigned char *types = NULL;
251  int need_revalidate = (filp->f_version != inode->i_version);
252 
253  if (pos > inode->i_size - EXOFS_DIR_REC_LEN(1))
254  return 0;
255 
256  types = exofs_filetype_table;
257 
258  for ( ; n < npages; n++, offset = 0) {
259  char *kaddr, *limit;
260  struct exofs_dir_entry *de;
261  struct page *page = exofs_get_page(inode, n);
262 
263  if (IS_ERR(page)) {
264  EXOFS_ERR("ERROR: bad page in directory(0x%lx)\n",
265  inode->i_ino);
266  filp->f_pos += PAGE_CACHE_SIZE - offset;
267  return PTR_ERR(page);
268  }
269  kaddr = page_address(page);
270  if (unlikely(need_revalidate)) {
271  if (offset) {
272  offset = exofs_validate_entry(kaddr, offset,
273  chunk_mask);
274  filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
275  }
276  filp->f_version = inode->i_version;
277  need_revalidate = 0;
278  }
279  de = (struct exofs_dir_entry *)(kaddr + offset);
280  limit = kaddr + exofs_last_byte(inode, n) -
282  for (; (char *)de <= limit; de = exofs_next_entry(de)) {
283  if (de->rec_len == 0) {
284  EXOFS_ERR("ERROR: "
285  "zero-length entry in directory(0x%lx)\n",
286  inode->i_ino);
287  exofs_put_page(page);
288  return -EIO;
289  }
290  if (de->inode_no) {
291  int over;
292  unsigned char d_type = DT_UNKNOWN;
293 
294  if (types && de->file_type < EXOFS_FT_MAX)
295  d_type = types[de->file_type];
296 
297  offset = (char *)de - kaddr;
298  over = filldir(dirent, de->name, de->name_len,
299  (n<<PAGE_CACHE_SHIFT) | offset,
300  le64_to_cpu(de->inode_no),
301  d_type);
302  if (over) {
303  exofs_put_page(page);
304  return 0;
305  }
306  }
307  filp->f_pos += le16_to_cpu(de->rec_len);
308  }
309  exofs_put_page(page);
310  }
311 
312  return 0;
313 }
314 
315 struct exofs_dir_entry *exofs_find_entry(struct inode *dir,
316  struct dentry *dentry, struct page **res_page)
317 {
318  const unsigned char *name = dentry->d_name.name;
319  int namelen = dentry->d_name.len;
320  unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
321  unsigned long start, n;
322  unsigned long npages = dir_pages(dir);
323  struct page *page = NULL;
324  struct exofs_i_info *oi = exofs_i(dir);
325  struct exofs_dir_entry *de;
326 
327  if (npages == 0)
328  goto out;
329 
330  *res_page = NULL;
331 
332  start = oi->i_dir_start_lookup;
333  if (start >= npages)
334  start = 0;
335  n = start;
336  do {
337  char *kaddr;
338  page = exofs_get_page(dir, n);
339  if (!IS_ERR(page)) {
340  kaddr = page_address(page);
341  de = (struct exofs_dir_entry *) kaddr;
342  kaddr += exofs_last_byte(dir, n) - reclen;
343  while ((char *) de <= kaddr) {
344  if (de->rec_len == 0) {
345  EXOFS_ERR("ERROR: zero-length entry in "
346  "directory(0x%lx)\n",
347  dir->i_ino);
348  exofs_put_page(page);
349  goto out;
350  }
351  if (exofs_match(namelen, name, de))
352  goto found;
353  de = exofs_next_entry(de);
354  }
355  exofs_put_page(page);
356  }
357  if (++n >= npages)
358  n = 0;
359  } while (n != start);
360 out:
361  return NULL;
362 
363 found:
364  *res_page = page;
365  oi->i_dir_start_lookup = n;
366  return de;
367 }
368 
369 struct exofs_dir_entry *exofs_dotdot(struct inode *dir, struct page **p)
370 {
371  struct page *page = exofs_get_page(dir, 0);
372  struct exofs_dir_entry *de = NULL;
373 
374  if (!IS_ERR(page)) {
375  de = exofs_next_entry(
376  (struct exofs_dir_entry *)page_address(page));
377  *p = page;
378  }
379  return de;
380 }
381 
383 {
384  struct page *page;
385  struct exofs_dir_entry *de;
386  ino_t ino;
387 
388  de = exofs_dotdot(child->d_inode, &page);
389  if (!de)
390  return 0;
391 
392  ino = le64_to_cpu(de->inode_no);
393  exofs_put_page(page);
394  return ino;
395 }
396 
397 ino_t exofs_inode_by_name(struct inode *dir, struct dentry *dentry)
398 {
399  ino_t res = 0;
400  struct exofs_dir_entry *de;
401  struct page *page;
402 
403  de = exofs_find_entry(dir, dentry, &page);
404  if (de) {
405  res = le64_to_cpu(de->inode_no);
406  exofs_put_page(page);
407  }
408  return res;
409 }
410 
411 int exofs_set_link(struct inode *dir, struct exofs_dir_entry *de,
412  struct page *page, struct inode *inode)
413 {
414  loff_t pos = page_offset(page) +
415  (char *) de - (char *) page_address(page);
416  unsigned len = le16_to_cpu(de->rec_len);
417  int err;
418 
419  lock_page(page);
420  err = exofs_write_begin(NULL, page->mapping, pos, len,
422  if (err)
423  EXOFS_ERR("exofs_set_link: exofs_write_begin FAILED => %d\n",
424  err);
425 
426  de->inode_no = cpu_to_le64(inode->i_ino);
427  exofs_set_de_type(de, inode);
428  if (likely(!err))
429  err = exofs_commit_chunk(page, pos, len);
430  exofs_put_page(page);
431  dir->i_mtime = dir->i_ctime = CURRENT_TIME;
432  mark_inode_dirty(dir);
433  return err;
434 }
435 
436 int exofs_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 = exofs_chunk_size(dir);
442  unsigned reclen = EXOFS_DIR_REC_LEN(namelen);
443  unsigned short rec_len, name_len;
444  struct page *page = NULL;
445  struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
446  struct exofs_dir_entry *de;
447  unsigned long npages = dir_pages(dir);
448  unsigned long n;
449  char *kaddr;
450  loff_t pos;
451  int err;
452 
453  for (n = 0; n <= npages; n++) {
454  char *dir_end;
455 
456  page = exofs_get_page(dir, n);
457  err = PTR_ERR(page);
458  if (IS_ERR(page))
459  goto out;
460  lock_page(page);
461  kaddr = page_address(page);
462  dir_end = kaddr + exofs_last_byte(dir, n);
463  de = (struct exofs_dir_entry *)kaddr;
464  kaddr += PAGE_CACHE_SIZE - reclen;
465  while ((char *)de <= kaddr) {
466  if ((char *)de == dir_end) {
467  name_len = 0;
468  rec_len = chunk_size;
469  de->rec_len = cpu_to_le16(chunk_size);
470  de->inode_no = 0;
471  goto got_it;
472  }
473  if (de->rec_len == 0) {
474  EXOFS_ERR("ERROR: exofs_add_link: "
475  "zero-length entry in directory(0x%lx)\n",
476  inode->i_ino);
477  err = -EIO;
478  goto out_unlock;
479  }
480  err = -EEXIST;
481  if (exofs_match(namelen, name, de))
482  goto out_unlock;
483  name_len = EXOFS_DIR_REC_LEN(de->name_len);
484  rec_len = le16_to_cpu(de->rec_len);
485  if (!de->inode_no && rec_len >= reclen)
486  goto got_it;
487  if (rec_len >= name_len + reclen)
488  goto got_it;
489  de = (struct exofs_dir_entry *) ((char *) de + rec_len);
490  }
491  unlock_page(page);
492  exofs_put_page(page);
493  }
494 
495  EXOFS_ERR("exofs_add_link: BAD dentry=%p or inode=0x%lx\n",
496  dentry, inode->i_ino);
497  return -EINVAL;
498 
499 got_it:
500  pos = page_offset(page) +
501  (char *)de - (char *)page_address(page);
502  err = exofs_write_begin(NULL, page->mapping, pos, rec_len, 0,
503  &page, NULL);
504  if (err)
505  goto out_unlock;
506  if (de->inode_no) {
507  struct exofs_dir_entry *de1 =
508  (struct exofs_dir_entry *)((char *)de + name_len);
509  de1->rec_len = cpu_to_le16(rec_len - name_len);
510  de->rec_len = cpu_to_le16(name_len);
511  de = de1;
512  }
513  de->name_len = namelen;
514  memcpy(de->name, name, namelen);
515  de->inode_no = cpu_to_le64(inode->i_ino);
516  exofs_set_de_type(de, inode);
517  err = exofs_commit_chunk(page, pos, rec_len);
518  dir->i_mtime = dir->i_ctime = CURRENT_TIME;
519  mark_inode_dirty(dir);
520  sbi->s_numfiles++;
521 
522 out_put:
523  exofs_put_page(page);
524 out:
525  return err;
526 out_unlock:
527  unlock_page(page);
528  goto out_put;
529 }
530 
531 int exofs_delete_entry(struct exofs_dir_entry *dir, struct page *page)
532 {
533  struct address_space *mapping = page->mapping;
534  struct inode *inode = mapping->host;
535  struct exofs_sb_info *sbi = inode->i_sb->s_fs_info;
536  char *kaddr = page_address(page);
537  unsigned from = ((char *)dir - kaddr) & ~(exofs_chunk_size(inode)-1);
538  unsigned to = ((char *)dir - kaddr) + le16_to_cpu(dir->rec_len);
539  loff_t pos;
540  struct exofs_dir_entry *pde = NULL;
541  struct exofs_dir_entry *de = (struct exofs_dir_entry *) (kaddr + from);
542  int err;
543 
544  while (de < dir) {
545  if (de->rec_len == 0) {
546  EXOFS_ERR("ERROR: exofs_delete_entry:"
547  "zero-length entry in directory(0x%lx)\n",
548  inode->i_ino);
549  err = -EIO;
550  goto out;
551  }
552  pde = de;
553  de = exofs_next_entry(de);
554  }
555  if (pde)
556  from = (char *)pde - (char *)page_address(page);
557  pos = page_offset(page) + from;
558  lock_page(page);
559  err = exofs_write_begin(NULL, page->mapping, pos, to - from, 0,
560  &page, NULL);
561  if (err)
562  EXOFS_ERR("exofs_delete_entry: exofs_write_begin FAILED => %d\n",
563  err);
564  if (pde)
565  pde->rec_len = cpu_to_le16(to - from);
566  dir->inode_no = 0;
567  if (likely(!err))
568  err = exofs_commit_chunk(page, pos, to - from);
569  inode->i_ctime = inode->i_mtime = CURRENT_TIME;
570  mark_inode_dirty(inode);
571  sbi->s_numfiles--;
572 out:
573  exofs_put_page(page);
574  return err;
575 }
576 
577 /* kept aligned on 4 bytes */
578 #define THIS_DIR ".\0\0"
579 #define PARENT_DIR "..\0"
580 
581 int exofs_make_empty(struct inode *inode, struct inode *parent)
582 {
583  struct address_space *mapping = inode->i_mapping;
584  struct page *page = grab_cache_page(mapping, 0);
585  unsigned chunk_size = exofs_chunk_size(inode);
586  struct exofs_dir_entry *de;
587  int err;
588  void *kaddr;
589 
590  if (!page)
591  return -ENOMEM;
592 
593  err = exofs_write_begin(NULL, page->mapping, 0, chunk_size, 0,
594  &page, NULL);
595  if (err) {
596  unlock_page(page);
597  goto fail;
598  }
599 
600  kaddr = kmap_atomic(page);
601  de = (struct exofs_dir_entry *)kaddr;
602  de->name_len = 1;
604  memcpy(de->name, THIS_DIR, sizeof(THIS_DIR));
605  de->inode_no = cpu_to_le64(inode->i_ino);
606  exofs_set_de_type(de, inode);
607 
608  de = (struct exofs_dir_entry *)(kaddr + EXOFS_DIR_REC_LEN(1));
609  de->name_len = 2;
610  de->rec_len = cpu_to_le16(chunk_size - EXOFS_DIR_REC_LEN(1));
611  de->inode_no = cpu_to_le64(parent->i_ino);
612  memcpy(de->name, PARENT_DIR, sizeof(PARENT_DIR));
613  exofs_set_de_type(de, inode);
614  kunmap_atomic(kaddr);
615  err = exofs_commit_chunk(page, 0, chunk_size);
616 fail:
617  page_cache_release(page);
618  return err;
619 }
620 
621 int exofs_empty_dir(struct inode *inode)
622 {
623  struct page *page = NULL;
624  unsigned long i, npages = dir_pages(inode);
625 
626  for (i = 0; i < npages; i++) {
627  char *kaddr;
628  struct exofs_dir_entry *de;
629  page = exofs_get_page(inode, i);
630 
631  if (IS_ERR(page))
632  continue;
633 
634  kaddr = page_address(page);
635  de = (struct exofs_dir_entry *)kaddr;
636  kaddr += exofs_last_byte(inode, i) - EXOFS_DIR_REC_LEN(1);
637 
638  while ((char *)de <= kaddr) {
639  if (de->rec_len == 0) {
640  EXOFS_ERR("ERROR: exofs_empty_dir: "
641  "zero-length directory entry"
642  "kaddr=%p, de=%p\n", kaddr, de);
643  goto not_empty;
644  }
645  if (de->inode_no != 0) {
646  /* check for . and .. */
647  if (de->name[0] != '.')
648  goto not_empty;
649  if (de->name_len > 2)
650  goto not_empty;
651  if (de->name_len < 2) {
652  if (le64_to_cpu(de->inode_no) !=
653  inode->i_ino)
654  goto not_empty;
655  } else if (de->name[1] != '.')
656  goto not_empty;
657  }
658  de = exofs_next_entry(de);
659  }
660  exofs_put_page(page);
661  }
662  return 1;
663 
664 not_empty:
665  exofs_put_page(page);
666  return 0;
667 }
668 
670  .llseek = generic_file_llseek,
671  .read = generic_read_dir,
672  .readdir = exofs_readdir,
673 };