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 16 #include <linux/pagemap.h> 17 #include <linux/highmem.h> 18 #include <linux/swap.h> 19 #include "sysv.h" 20 21 static int sysv_readdir(struct file *, void *, filldir_t); 22 23 const struct file_operations sysv_dir_operations = { 24 .llseek = generic_file_llseek, 25 .read = generic_read_dir, 26 .readdir = sysv_readdir, 27 .fsync = generic_file_fsync, 28 }; 29 30 static inline void dir_put_page(struct page *page) 31 { 32 kunmap(page); 33 page_cache_release(page); 34 } 35 36 static inline unsigned long dir_pages(struct inode *inode) 37 { 38 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; 39 } 40 41 static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len) 42 { 43 struct address_space *mapping = page->mapping; 44 struct inode *dir = mapping->host; 45 int err = 0; 46 47 block_write_end(NULL, mapping, pos, len, len, page, NULL); 48 if (pos+len > dir->i_size) { 49 i_size_write(dir, pos+len); 50 mark_inode_dirty(dir); 51 } 52 if (IS_DIRSYNC(dir)) 53 err = write_one_page(page, 1); 54 else 55 unlock_page(page); 56 return err; 57 } 58 59 static struct page * dir_get_page(struct inode *dir, unsigned long n) 60 { 61 struct address_space *mapping = dir->i_mapping; 62 struct page *page = read_mapping_page(mapping, n, NULL); 63 if (!IS_ERR(page)) 64 kmap(page); 65 return page; 66 } 67 68 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir) 69 { 70 unsigned long pos = filp->f_pos; 71 struct inode *inode = file_inode(filp); 72 struct super_block *sb = inode->i_sb; 73 unsigned offset = pos & ~PAGE_CACHE_MASK; 74 unsigned long n = pos >> PAGE_CACHE_SHIFT; 75 unsigned long npages = dir_pages(inode); 76 77 pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1); 78 if (pos >= inode->i_size) 79 goto done; 80 81 for ( ; n < npages; n++, offset = 0) { 82 char *kaddr, *limit; 83 struct sysv_dir_entry *de; 84 struct page *page = dir_get_page(inode, n); 85 86 if (IS_ERR(page)) 87 continue; 88 kaddr = (char *)page_address(page); 89 de = (struct sysv_dir_entry *)(kaddr+offset); 90 limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE; 91 for ( ;(char*)de <= limit; de++) { 92 char *name = de->name; 93 int over; 94 95 if (!de->inode) 96 continue; 97 98 offset = (char *)de - kaddr; 99 100 over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN), 101 ((loff_t)n<<PAGE_CACHE_SHIFT) | offset, 102 fs16_to_cpu(SYSV_SB(sb), de->inode), 103 DT_UNKNOWN); 104 if (over) { 105 dir_put_page(page); 106 goto done; 107 } 108 } 109 dir_put_page(page); 110 } 111 112 done: 113 filp->f_pos = ((loff_t)n << PAGE_CACHE_SHIFT) | offset; 114 return 0; 115 } 116 117 /* compare strings: name[0..len-1] (not zero-terminated) and 118 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1]) 119 */ 120 static inline int namecompare(int len, int maxlen, 121 const char * name, const char * buffer) 122 { 123 if (len < maxlen && buffer[len]) 124 return 0; 125 return !memcmp(name, buffer, len); 126 } 127 128 /* 129 * sysv_find_entry() 130 * 131 * finds an entry in the specified directory with the wanted name. It 132 * returns the cache buffer in which the entry was found, and the entry 133 * itself (as a parameter - res_dir). It does NOT read the inode of the 134 * entry - you'll have to do that yourself if you want to. 135 */ 136 struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page) 137 { 138 const char * name = dentry->d_name.name; 139 int namelen = dentry->d_name.len; 140 struct inode * dir = dentry->d_parent->d_inode; 141 unsigned long start, n; 142 unsigned long npages = dir_pages(dir); 143 struct page *page = NULL; 144 struct sysv_dir_entry *de; 145 146 *res_page = NULL; 147 148 start = SYSV_I(dir)->i_dir_start_lookup; 149 if (start >= npages) 150 start = 0; 151 n = start; 152 153 do { 154 char *kaddr; 155 page = dir_get_page(dir, n); 156 if (!IS_ERR(page)) { 157 kaddr = (char*)page_address(page); 158 de = (struct sysv_dir_entry *) kaddr; 159 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; 160 for ( ; (char *) de <= kaddr ; de++) { 161 if (!de->inode) 162 continue; 163 if (namecompare(namelen, SYSV_NAMELEN, 164 name, de->name)) 165 goto found; 166 } 167 dir_put_page(page); 168 } 169 170 if (++n >= npages) 171 n = 0; 172 } while (n != start); 173 174 return NULL; 175 176 found: 177 SYSV_I(dir)->i_dir_start_lookup = n; 178 *res_page = page; 179 return de; 180 } 181 182 int sysv_add_link(struct dentry *dentry, struct inode *inode) 183 { 184 struct inode *dir = dentry->d_parent->d_inode; 185 const char * name = dentry->d_name.name; 186 int namelen = dentry->d_name.len; 187 struct page *page = NULL; 188 struct sysv_dir_entry * de; 189 unsigned long npages = dir_pages(dir); 190 unsigned long n; 191 char *kaddr; 192 loff_t pos; 193 int err; 194 195 /* We take care of directory expansion in the same loop */ 196 for (n = 0; n <= npages; n++) { 197 page = dir_get_page(dir, n); 198 err = PTR_ERR(page); 199 if (IS_ERR(page)) 200 goto out; 201 kaddr = (char*)page_address(page); 202 de = (struct sysv_dir_entry *)kaddr; 203 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; 204 while ((char *)de <= kaddr) { 205 if (!de->inode) 206 goto got_it; 207 err = -EEXIST; 208 if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 209 goto out_page; 210 de++; 211 } 212 dir_put_page(page); 213 } 214 BUG(); 215 return -EINVAL; 216 217 got_it: 218 pos = page_offset(page) + 219 (char*)de - (char*)page_address(page); 220 lock_page(page); 221 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE); 222 if (err) 223 goto out_unlock; 224 memcpy (de->name, name, namelen); 225 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2); 226 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 227 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE); 228 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 229 mark_inode_dirty(dir); 230 out_page: 231 dir_put_page(page); 232 out: 233 return err; 234 out_unlock: 235 unlock_page(page); 236 goto out_page; 237 } 238 239 int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page) 240 { 241 struct inode *inode = page->mapping->host; 242 char *kaddr = (char*)page_address(page); 243 loff_t pos = page_offset(page) + (char *)de - kaddr; 244 int err; 245 246 lock_page(page); 247 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE); 248 BUG_ON(err); 249 de->inode = 0; 250 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE); 251 dir_put_page(page); 252 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 253 mark_inode_dirty(inode); 254 return err; 255 } 256 257 int sysv_make_empty(struct inode *inode, struct inode *dir) 258 { 259 struct page *page = grab_cache_page(inode->i_mapping, 0); 260 struct sysv_dir_entry * de; 261 char *base; 262 int err; 263 264 if (!page) 265 return -ENOMEM; 266 err = sysv_prepare_chunk(page, 0, 2 * SYSV_DIRSIZE); 267 if (err) { 268 unlock_page(page); 269 goto fail; 270 } 271 kmap(page); 272 273 base = (char*)page_address(page); 274 memset(base, 0, PAGE_CACHE_SIZE); 275 276 de = (struct sysv_dir_entry *) base; 277 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 278 strcpy(de->name,"."); 279 de++; 280 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino); 281 strcpy(de->name,".."); 282 283 kunmap(page); 284 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE); 285 fail: 286 page_cache_release(page); 287 return err; 288 } 289 290 /* 291 * routine to check that the specified directory is empty (for rmdir) 292 */ 293 int sysv_empty_dir(struct inode * inode) 294 { 295 struct super_block *sb = inode->i_sb; 296 struct page *page = NULL; 297 unsigned long i, npages = dir_pages(inode); 298 299 for (i = 0; i < npages; i++) { 300 char *kaddr; 301 struct sysv_dir_entry * de; 302 page = dir_get_page(inode, i); 303 304 if (IS_ERR(page)) 305 continue; 306 307 kaddr = (char *)page_address(page); 308 de = (struct sysv_dir_entry *)kaddr; 309 kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE; 310 311 for ( ;(char *)de <= kaddr; de++) { 312 if (!de->inode) 313 continue; 314 /* check for . and .. */ 315 if (de->name[0] != '.') 316 goto not_empty; 317 if (!de->name[1]) { 318 if (de->inode == cpu_to_fs16(SYSV_SB(sb), 319 inode->i_ino)) 320 continue; 321 goto not_empty; 322 } 323 if (de->name[1] != '.' || de->name[2]) 324 goto not_empty; 325 } 326 dir_put_page(page); 327 } 328 return 1; 329 330 not_empty: 331 dir_put_page(page); 332 return 0; 333 } 334 335 /* Releases the page */ 336 void sysv_set_link(struct sysv_dir_entry *de, struct page *page, 337 struct inode *inode) 338 { 339 struct inode *dir = page->mapping->host; 340 loff_t pos = page_offset(page) + 341 (char *)de-(char*)page_address(page); 342 int err; 343 344 lock_page(page); 345 err = sysv_prepare_chunk(page, pos, SYSV_DIRSIZE); 346 BUG_ON(err); 347 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 348 err = dir_commit_chunk(page, pos, SYSV_DIRSIZE); 349 dir_put_page(page); 350 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 351 mark_inode_dirty(dir); 352 } 353 354 struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p) 355 { 356 struct page *page = dir_get_page(dir, 0); 357 struct sysv_dir_entry *de = NULL; 358 359 if (!IS_ERR(page)) { 360 de = (struct sysv_dir_entry*) page_address(page) + 1; 361 *p = page; 362 } 363 return de; 364 } 365 366 ino_t sysv_inode_by_name(struct dentry *dentry) 367 { 368 struct page *page; 369 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page); 370 ino_t res = 0; 371 372 if (de) { 373 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode); 374 dir_put_page(page); 375 } 376 return res; 377 } 378