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