Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | } |