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/smp_lock.h> 19 #include "sysv.h" 20 21 static int sysv_readdir(struct file *, void *, filldir_t); 22 23 struct file_operations sysv_dir_operations = { 24 .read = generic_read_dir, 25 .readdir = sysv_readdir, 26 .fsync = sysv_sync_file, 27 }; 28 29 static inline void dir_put_page(struct page *page) 30 { 31 kunmap(page); 32 page_cache_release(page); 33 } 34 35 static inline unsigned long dir_pages(struct inode *inode) 36 { 37 return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT; 38 } 39 40 static int dir_commit_chunk(struct page *page, unsigned from, unsigned to) 41 { 42 struct inode *dir = (struct inode *)page->mapping->host; 43 int err = 0; 44 45 page->mapping->a_ops->commit_write(NULL, page, from, to); 46 if (IS_DIRSYNC(dir)) 47 err = write_one_page(page, 1); 48 else 49 unlock_page(page); 50 return err; 51 } 52 53 static struct page * dir_get_page(struct inode *dir, unsigned long n) 54 { 55 struct address_space *mapping = dir->i_mapping; 56 struct page *page = read_cache_page(mapping, n, 57 (filler_t*)mapping->a_ops->readpage, NULL); 58 if (!IS_ERR(page)) { 59 wait_on_page_locked(page); 60 kmap(page); 61 if (!PageUptodate(page)) 62 goto fail; 63 } 64 return page; 65 66 fail: 67 dir_put_page(page); 68 return ERR_PTR(-EIO); 69 } 70 71 static int sysv_readdir(struct file * filp, void * dirent, filldir_t filldir) 72 { 73 unsigned long pos = filp->f_pos; 74 struct inode *inode = filp->f_dentry->d_inode; 75 struct super_block *sb = inode->i_sb; 76 unsigned offset = pos & ~PAGE_CACHE_MASK; 77 unsigned long n = pos >> PAGE_CACHE_SHIFT; 78 unsigned long npages = dir_pages(inode); 79 80 lock_kernel(); 81 82 pos = (pos + SYSV_DIRSIZE-1) & ~(SYSV_DIRSIZE-1); 83 if (pos >= inode->i_size) 84 goto done; 85 86 for ( ; n < npages; n++, offset = 0) { 87 char *kaddr, *limit; 88 struct sysv_dir_entry *de; 89 struct page *page = dir_get_page(inode, n); 90 91 if (IS_ERR(page)) 92 continue; 93 kaddr = (char *)page_address(page); 94 de = (struct sysv_dir_entry *)(kaddr+offset); 95 limit = kaddr + PAGE_CACHE_SIZE - SYSV_DIRSIZE; 96 for ( ;(char*)de <= limit; de++) { 97 char *name = de->name; 98 int over; 99 100 if (!de->inode) 101 continue; 102 103 offset = (char *)de - kaddr; 104 105 over = filldir(dirent, name, strnlen(name,SYSV_NAMELEN), 106 (n<<PAGE_CACHE_SHIFT) | offset, 107 fs16_to_cpu(SYSV_SB(sb), de->inode), 108 DT_UNKNOWN); 109 if (over) { 110 dir_put_page(page); 111 goto done; 112 } 113 } 114 dir_put_page(page); 115 } 116 117 done: 118 filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset; 119 unlock_kernel(); 120 return 0; 121 } 122 123 /* compare strings: name[0..len-1] (not zero-terminated) and 124 * buffer[0..] (filled with zeroes up to buffer[0..maxlen-1]) 125 */ 126 static inline int namecompare(int len, int maxlen, 127 const char * name, const char * buffer) 128 { 129 if (len < maxlen && buffer[len]) 130 return 0; 131 return !memcmp(name, buffer, len); 132 } 133 134 /* 135 * sysv_find_entry() 136 * 137 * finds an entry in the specified directory with the wanted name. It 138 * returns the cache buffer in which the entry was found, and the entry 139 * itself (as a parameter - res_dir). It does NOT read the inode of the 140 * entry - you'll have to do that yourself if you want to. 141 */ 142 struct sysv_dir_entry *sysv_find_entry(struct dentry *dentry, struct page **res_page) 143 { 144 const char * name = dentry->d_name.name; 145 int namelen = dentry->d_name.len; 146 struct inode * dir = dentry->d_parent->d_inode; 147 unsigned long start, n; 148 unsigned long npages = dir_pages(dir); 149 struct page *page = NULL; 150 struct sysv_dir_entry *de; 151 152 *res_page = NULL; 153 154 start = SYSV_I(dir)->i_dir_start_lookup; 155 if (start >= npages) 156 start = 0; 157 n = start; 158 159 do { 160 char *kaddr; 161 page = dir_get_page(dir, n); 162 if (!IS_ERR(page)) { 163 kaddr = (char*)page_address(page); 164 de = (struct sysv_dir_entry *) kaddr; 165 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; 166 for ( ; (char *) de <= kaddr ; de++) { 167 if (!de->inode) 168 continue; 169 if (namecompare(namelen, SYSV_NAMELEN, 170 name, de->name)) 171 goto found; 172 } 173 } 174 dir_put_page(page); 175 176 if (++n >= npages) 177 n = 0; 178 } while (n != start); 179 180 return NULL; 181 182 found: 183 SYSV_I(dir)->i_dir_start_lookup = n; 184 *res_page = page; 185 return de; 186 } 187 188 int sysv_add_link(struct dentry *dentry, struct inode *inode) 189 { 190 struct inode *dir = dentry->d_parent->d_inode; 191 const char * name = dentry->d_name.name; 192 int namelen = dentry->d_name.len; 193 struct page *page = NULL; 194 struct sysv_dir_entry * de; 195 unsigned long npages = dir_pages(dir); 196 unsigned long n; 197 char *kaddr; 198 unsigned from, to; 199 int err; 200 201 /* We take care of directory expansion in the same loop */ 202 for (n = 0; n <= npages; n++) { 203 page = dir_get_page(dir, n); 204 err = PTR_ERR(page); 205 if (IS_ERR(page)) 206 goto out; 207 kaddr = (char*)page_address(page); 208 de = (struct sysv_dir_entry *)kaddr; 209 kaddr += PAGE_CACHE_SIZE - SYSV_DIRSIZE; 210 while ((char *)de <= kaddr) { 211 if (!de->inode) 212 goto got_it; 213 err = -EEXIST; 214 if (namecompare(namelen, SYSV_NAMELEN, name, de->name)) 215 goto out_page; 216 de++; 217 } 218 dir_put_page(page); 219 } 220 BUG(); 221 return -EINVAL; 222 223 got_it: 224 from = (char*)de - (char*)page_address(page); 225 to = from + SYSV_DIRSIZE; 226 lock_page(page); 227 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 228 if (err) 229 goto out_unlock; 230 memcpy (de->name, name, namelen); 231 memset (de->name + namelen, 0, SYSV_DIRSIZE - namelen - 2); 232 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 233 err = dir_commit_chunk(page, from, to); 234 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 235 mark_inode_dirty(dir); 236 out_page: 237 dir_put_page(page); 238 out: 239 return err; 240 out_unlock: 241 unlock_page(page); 242 goto out_page; 243 } 244 245 int sysv_delete_entry(struct sysv_dir_entry *de, struct page *page) 246 { 247 struct address_space *mapping = page->mapping; 248 struct inode *inode = (struct inode*)mapping->host; 249 char *kaddr = (char*)page_address(page); 250 unsigned from = (char*)de - kaddr; 251 unsigned to = from + SYSV_DIRSIZE; 252 int err; 253 254 lock_page(page); 255 err = mapping->a_ops->prepare_write(NULL, page, from, to); 256 if (err) 257 BUG(); 258 de->inode = 0; 259 err = dir_commit_chunk(page, from, to); 260 dir_put_page(page); 261 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 262 mark_inode_dirty(inode); 263 return err; 264 } 265 266 int sysv_make_empty(struct inode *inode, struct inode *dir) 267 { 268 struct address_space *mapping = inode->i_mapping; 269 struct page *page = grab_cache_page(mapping, 0); 270 struct sysv_dir_entry * de; 271 char *base; 272 int err; 273 274 if (!page) 275 return -ENOMEM; 276 kmap(page); 277 err = mapping->a_ops->prepare_write(NULL, page, 0, 2 * SYSV_DIRSIZE); 278 if (err) { 279 unlock_page(page); 280 goto fail; 281 } 282 283 base = (char*)page_address(page); 284 memset(base, 0, PAGE_CACHE_SIZE); 285 286 de = (struct sysv_dir_entry *) base; 287 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 288 strcpy(de->name,"."); 289 de++; 290 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), dir->i_ino); 291 strcpy(de->name,".."); 292 293 err = dir_commit_chunk(page, 0, 2 * SYSV_DIRSIZE); 294 fail: 295 kunmap(page); 296 page_cache_release(page); 297 return err; 298 } 299 300 /* 301 * routine to check that the specified directory is empty (for rmdir) 302 */ 303 int sysv_empty_dir(struct inode * inode) 304 { 305 struct super_block *sb = inode->i_sb; 306 struct page *page = NULL; 307 unsigned long i, npages = dir_pages(inode); 308 309 for (i = 0; i < npages; i++) { 310 char *kaddr; 311 struct sysv_dir_entry * de; 312 page = dir_get_page(inode, i); 313 314 if (IS_ERR(page)) 315 continue; 316 317 kaddr = (char *)page_address(page); 318 de = (struct sysv_dir_entry *)kaddr; 319 kaddr += PAGE_CACHE_SIZE-SYSV_DIRSIZE; 320 321 for ( ;(char *)de <= kaddr; de++) { 322 if (!de->inode) 323 continue; 324 /* check for . and .. */ 325 if (de->name[0] != '.') 326 goto not_empty; 327 if (!de->name[1]) { 328 if (de->inode == cpu_to_fs16(SYSV_SB(sb), 329 inode->i_ino)) 330 continue; 331 goto not_empty; 332 } 333 if (de->name[1] != '.' || de->name[2]) 334 goto not_empty; 335 } 336 dir_put_page(page); 337 } 338 return 1; 339 340 not_empty: 341 dir_put_page(page); 342 return 0; 343 } 344 345 /* Releases the page */ 346 void sysv_set_link(struct sysv_dir_entry *de, struct page *page, 347 struct inode *inode) 348 { 349 struct inode *dir = (struct inode*)page->mapping->host; 350 unsigned from = (char *)de-(char*)page_address(page); 351 unsigned to = from + SYSV_DIRSIZE; 352 int err; 353 354 lock_page(page); 355 err = page->mapping->a_ops->prepare_write(NULL, page, from, to); 356 if (err) 357 BUG(); 358 de->inode = cpu_to_fs16(SYSV_SB(inode->i_sb), inode->i_ino); 359 err = dir_commit_chunk(page, from, to); 360 dir_put_page(page); 361 dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC; 362 mark_inode_dirty(dir); 363 } 364 365 struct sysv_dir_entry * sysv_dotdot (struct inode *dir, struct page **p) 366 { 367 struct page *page = dir_get_page(dir, 0); 368 struct sysv_dir_entry *de = NULL; 369 370 if (!IS_ERR(page)) { 371 de = (struct sysv_dir_entry*) page_address(page) + 1; 372 *p = page; 373 } 374 return de; 375 } 376 377 ino_t sysv_inode_by_name(struct dentry *dentry) 378 { 379 struct page *page; 380 struct sysv_dir_entry *de = sysv_find_entry (dentry, &page); 381 ino_t res = 0; 382 383 if (de) { 384 res = fs16_to_cpu(SYSV_SB(dentry->d_sb), de->inode); 385 dir_put_page(page); 386 } 387 return res; 388 } 389