dir.c 8.9 KB

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  1. /*
  2. * linux/fs/sysv/dir.c
  3. *
  4. * minix/dir.c
  5. * Copyright (C) 1991, 1992 Linus Torvalds
  6. *
  7. * coh/dir.c
  8. * Copyright (C) 1993 Pascal Haible, Bruno Haible
  9. *
  10. * sysv/dir.c
  11. * Copyright (C) 1993 Bruno Haible
  12. *
  13. * SystemV/Coherent directory handling functions
  14. */
  15. #include <linux/pagemap.h>
  16. #include <linux/highmem.h>
  17. #include <linux/smp_lock.h>
  18. #include "sysv.h"
  19. static int sysv_readdir(struct file *, void *, filldir_t);
  20. const struct file_operations sysv_dir_operations = {
  21. .read = generic_read_dir,
  22. .readdir = sysv_readdir,
  23. .fsync = sysv_sync_file,
  24. };
  25. static inline void dir_put_page(struct page *page)
  26. {
  27. kunmap(page);
  28. page_cache_release(page);
  29. }
  30. static inline unsigned long dir_pages(struct inode *inode)
  31. {
  32. return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
  33. }
  34. static int dir_commit_chunk(struct page *page, unsigned from, unsigned to)
  35. {
  36. struct inode *dir = (struct inode *)page->mapping->host;
  37. int err = 0;
  38. page->mapping->a_ops->commit_write(NULL, page, from, to);
  39. if (IS_DIRSYNC(dir))
  40. err = write_one_page(page, 1);
  41. else
  42. unlock_page(page);
  43. return err;
  44. }
  45. static struct page * dir_get_page(struct inode *dir, unsigned long n)
  46. {
  47. struct address_space *mapping = dir->i_mapping;
  48. struct page *page = read_mapping_page(mapping, n, NULL);
  49. if (!IS_ERR(page)) {
  50. wait_on_page_locked(page);
  51. kmap(page);
  52. if (!PageUptodate(page))
  53. goto fail;
  54. }
  55. return page;
  56. fail:
  57. dir_put_page(page);
  58. return ERR_PTR(-EIO);
  59. }
  60. static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir)
  61. {
  62. unsigned long pos = filp->f_pos;
  63. struct inode *inode = filp->f_path.dentry->d_inode;
  64. struct super_block *sb = inode->i_sb;
  65. unsigned offset = pos & ~PAGE_CACHE_MASK;
  66. unsigned long n = pos >> PAGE_CACHE_SHIFT;
  67. unsigned long npages = dir_pages(inode);
  68. lock_kernel();
  69. pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1);
  70. if (pos >= inode->i_size)
  71. goto done;
  72. for ( ; n < npages; n++, offset = 0) {
  73. char *kaddr, *limit;
  74. struct sysv_dir_entry *de;
  75. struct page *page = dir_get_page(inode, n);
  76. if (IS_ERR(page))
  77. continue;
  78. kaddr = (char *)page_address(page);
  79. de = (struct sysv_dir_entry *)(kaddr+offset);
  80. limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE;
  81. for ( ;(char*)de <= limit; de++) {
  82. char *name = de->name;
  83. int over;
  84. if (!de->inode)
  85. continue;
  86. offset = (char *)de - kaddr;
  87. over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN),
  88. ((loff_t)n<<PAGE_CACHE_SHIFT) | offset,
  89. fs16_to_cpu(SYSV_SB(sb), de->inode),
  90. DT_UNKNOWN);
  91. if (over) {
  92. dir_put_page(page);
  93. goto done;
  94. }
  95. }
  96. dir_put_page(page);
  97. }
  98. done:
  99. filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset;
  100. unlock_kernel();
  101. return 0;
  102. }
  103. /* compare strings: name[0..len-1] (not zero-terminated) and
  104. * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1])
  105. */
  106. static inline int namecompare(int len, int maxlen,
  107. const char * name, const char * buffer)
  108. {
  109. if (len < maxlen && buffer[len])
  110. return 0;
  111. return !memcmp(name, buffer, len);
  112. }
  113. /*
  114. * sysv_find_entry()
  115. *
  116. * finds an entry in the specified directory with the wanted name. It
  117. * returns the cache buffer in which the entry was found, and the entry
  118. * itself (as a parameter - res_dir). It does NOT read the inode of the
  119. * entry - you'll have to do that yourself if you want to.
  120. */
  121. struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page)
  122. {
  123. const char * name = dentry->d_name.name;
  124. int namelen = dentry->d_name.len;
  125. struct inode * dir = dentry->d_parent->d_inode;
  126. unsigned long start, n;
  127. unsigned long npages = dir_pages(dir);
  128. struct page *page = NULL;
  129. struct sysv_dir_entry *de;
  130. *res_page = NULL;
  131. start = SYSV_I(dir)->i_dir_start_lookup;
  132. if (start >= npages)
  133. start = 0;
  134. n = start;
  135. do {
  136. char *kaddr;
  137. page = dir_get_page(dir, n);
  138. if (!IS_ERR(page)) {
  139. kaddr = (char*)page_address(page);
  140. de = (struct sysv_dir_entry *) kaddr;
  141. kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
  142. for ( ; (char *) de <= kaddr ; de++) {
  143. if (!de->inode)
  144. continue;
  145. if (namecompare(namelen, SYSV_NAMELEN,
  146. name, de->name))
  147. goto found;
  148. }
  149. }
  150. dir_put_page(page);
  151. if (++n >= npages)
  152. n = 0;
  153. } while (n != start);
  154. return NULL;
  155. found:
  156. SYSV_I(dir)->i_dir_start_lookup = n;
  157. *res_page = page;
  158. return de;
  159. }
  160. int sysv_add_link(struct dentry *dentry, struct inode *inode)
  161. {
  162. struct inode *dir = dentry->d_parent->d_inode;
  163. const char * name = dentry->d_name.name;
  164. int namelen = dentry->d_name.len;
  165. struct page *page = NULL;
  166. struct sysv_dir_entry * de;
  167. unsigned long npages = dir_pages(dir);
  168. unsigned long n;
  169. char *kaddr;
  170. unsigned from, to;
  171. int err;
  172. /* We take care of directory expansion in the same loop */
  173. for (n = 0; n <= npages; n++) {
  174. page = dir_get_page(dir, n);
  175. err = PTR_ERR(page);
  176. if (IS_ERR(page))
  177. goto out;
  178. kaddr = (char*)page_address(page);
  179. de = (struct sysv_dir_entry *)kaddr;
  180. kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE;
  181. while ((char *)de <= kaddr) {
  182. if (!de->inode)
  183. goto got_it;
  184. err = -EEXIST;
  185. if (namecompare(namelen, SYSV_NAMELEN, name, de->name))
  186. goto out_page;
  187. de++;
  188. }
  189. dir_put_page(page);
  190. }
  191. BUG();
  192. return -EINVAL;
  193. got_it:
  194. from = (char*)de - (char*)page_address(page);
  195. to = from + SYSV_DIRSIZE;
  196. lock_page(page);
  197. err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
  198. if (err)
  199. goto out_unlock;
  200. memcpy (de->name, name, namelen);
  201. memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2);
  202. de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
  203. err = dir_commit_chunk(page, from, to);
  204. dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
  205. mark_inode_dirty(dir);
  206. out_page:
  207. dir_put_page(page);
  208. out:
  209. return err;
  210. out_unlock:
  211. unlock_page(page);
  212. goto out_page;
  213. }
  214. int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page)
  215. {
  216. struct address_space *mapping = page->mapping;
  217. struct inode *inode = (struct inode*)mapping->host;
  218. char *kaddr = (char*)page_address(page);
  219. unsigned from = (char*)de - kaddr;
  220. unsigned to = from + SYSV_DIRSIZE;
  221. int err;
  222. lock_page(page);
  223. err = mapping->a_ops->prepare_write(NULL, page, from, to);
  224. BUG_ON(err);
  225. de->inode = 0;
  226. err = dir_commit_chunk(page, from, to);
  227. dir_put_page(page);
  228. inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
  229. mark_inode_dirty(inode);
  230. return err;
  231. }
  232. int sysv_make_empty(struct inode *inode, struct inode *dir)
  233. {
  234. struct address_space *mapping = inode->i_mapping;
  235. struct page *page = grab_cache_page(mapping, 0);
  236. struct sysv_dir_entry * de;
  237. char *base;
  238. int err;
  239. if (!page)
  240. return -ENOMEM;
  241. kmap(page);
  242. err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE);
  243. if (err) {
  244. unlock_page(page);
  245. goto fail;
  246. }
  247. base = (char*)page_address(page);
  248. memset(base, 0, PAGE_CACHE_SIZE);
  249. de = (struct sysv_dir_entry *) base;
  250. de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
  251. strcpy(de->name,".");
  252. de++;
  253. de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino);
  254. strcpy(de->name,"..");
  255. err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE);
  256. fail:
  257. kunmap(page);
  258. page_cache_release(page);
  259. return err;
  260. }
  261. /*
  262. * routine to check that the specified directory is empty (for rmdir)
  263. */
  264. int sysv_empty_dir(struct inode * inode)
  265. {
  266. struct super_block *sb = inode->i_sb;
  267. struct page *page = NULL;
  268. unsigned long i, npages = dir_pages(inode);
  269. for (i = 0; i < npages; i++) {
  270. char *kaddr;
  271. struct sysv_dir_entry * de;
  272. page = dir_get_page(inode, i);
  273. if (IS_ERR(page))
  274. continue;
  275. kaddr = (char *)page_address(page);
  276. de = (struct sysv_dir_entry *)kaddr;
  277. kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE;
  278. for ( ;(char *)de <= kaddr; de++) {
  279. if (!de->inode)
  280. continue;
  281. /* check for . and .. */
  282. if (de->name[0] != '.')
  283. goto not_empty;
  284. if (!de->name[1]) {
  285. if (de->inode == cpu_to_fs16(SYSV_SB(sb),
  286. inode->i_ino))
  287. continue;
  288. goto not_empty;
  289. }
  290. if (de->name[1] != '.' || de->name[2])
  291. goto not_empty;
  292. }
  293. dir_put_page(page);
  294. }
  295. return 1;
  296. not_empty:
  297. dir_put_page(page);
  298. return 0;
  299. }
  300. /* Releases the page */
  301. void sysv_set_link(struct sysv_dir_entry *de, struct page *page,
  302. struct inode *inode)
  303. {
  304. struct inode *dir = (struct inode*)page->mapping->host;
  305. unsigned from = (char *)de-(char*)page_address(page);
  306. unsigned to = from + SYSV_DIRSIZE;
  307. int err;
  308. lock_page(page);
  309. err = page->mapping->a_ops->prepare_write(NULL, page, from, to);
  310. BUG_ON(err);
  311. de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino);
  312. err = dir_commit_chunk(page, from, to);
  313. dir_put_page(page);
  314. dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
  315. mark_inode_dirty(dir);
  316. }
  317. struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p)
  318. {
  319. struct page *page = dir_get_page(dir, 0);
  320. struct sysv_dir_entry *de = NULL;
  321. if (!IS_ERR(page)) {
  322. de = (struct sysv_dir_entry*) page_address(page) + 1;
  323. *p = page;
  324. }
  325. return de;
  326. }
  327. ino_t sysv_inode_by_name(struct dentry *dentry)
  328. {
  329. struct page *page;
  330. struct sysv_dir_entry *de = sysv_find_entry (dentry, &page);
  331. ino_t res = 0;
  332. if (de) {
  333. res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode);
  334. dir_put_page(page);
  335. }
  336. return res;
  337. }