fs/minix/dir.c

   1 /*
   2  *  linux/fs/minix/dir.c
   3  *
   4  *  Copyright (C) 1991, 1992 Linus Torvalds
   5  *
   6  *  minix directory handling functions
   7  *
   8  *  Updated to filesystem version 3 by Daniel Aragones
   9  */
  10
  11 #include "minix.h"
  12 #include <linux/buffer_head.h>
  13 #include <linux/highmem.h>
  14 #include <linux/swap.h>
  15
  16 typedef struct minix_dir_entry minix_dirent;
  17 typedef struct minix3_dir_entry minix3_dirent;
  18
  19 static int minix_readdir(struct file *, void *, filldir_t);
  20
  21 const struct file_operations minix_dir_operations = {
  22         .llseek         = generic_file_llseek,
  23         .read           = generic_read_dir,
  24         .readdir        = minix_readdir,
  25         .fsync          = simple_fsync,
  26 };
  27
  28 static inline void dir_put_page(struct page *page)
  29 {
  30         kunmap(page);
  31         page_cache_release(page);
  32 }
  33
  34 /*
  35  * Return the offset into page `page_nr' of the last valid
  36  * byte in that page, plus one.
  37  */
  38 static unsigned
  39 minix_last_byte(struct inode *inode, unsigned long page_nr)
  40 {
  41         unsigned last_byte = PAGE_CACHE_SIZE;
  42
  43         if (page_nr == (inode->i_size >> PAGE_CACHE_SHIFT))
  44                 last_byte = inode->i_size & (PAGE_CACHE_SIZE - 1);
  45         return last_byte;
  46 }
  47
  48 static inline unsigned long dir_pages(struct inode *inode)
  49 {
  50         return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
  51 }
  52
  53 static int dir_commit_chunk(struct page *page, loff_t pos, unsigned len)
  54 {
  55         struct address_space *mapping = page->mapping;
  56         struct inode *dir = mapping->host;
  57         int err = 0;
  58         block_write_end(NULL, mapping, pos, len, len, page, NULL);
  59
  60         if (pos+len > dir->i_size) {
  61                 i_size_write(dir, pos+len);
  62                 mark_inode_dirty(dir);
  63         }
  64         if (IS_DIRSYNC(dir))
  65                 err = write_one_page(page, 1);
  66         else
  67                 unlock_page(page);
  68         return err;
  69 }
  70
  71 static struct page * dir_get_page(struct inode *dir, unsigned long n)
  72 {
  73         struct address_space *mapping = dir->i_mapping;
  74         struct page *page = read_mapping_page(mapping, n, NULL);
  75         if (!IS_ERR(page)) {
  76                 kmap(page);
  77                 if (!PageUptodate(page))
  78                         goto fail;
  79         }
  80         return page;
  81
  82 fail:
  83         dir_put_page(page);
  84         return ERR_PTR(-EIO);
  85 }
  86
  87 static inline void *minix_next_entry(void *de, struct minix_sb_info *sbi)
  88 {
  89         return (void*)((char*)de + sbi->s_dirsize);
  90 }
  91
  92 static int minix_readdir(struct file * filp, void * dirent, filldir_t filldir)
  93 {
  94         unsigned long pos = filp->f_pos;
  95         struct inode *inode = filp->f_path.dentry->d_inode;
  96         struct super_block *sb = inode->i_sb;
  97         unsigned offset = pos & ~PAGE_CACHE_MASK;
  98         unsigned long n = pos >> PAGE_CACHE_SHIFT;
  99         unsigned long npages = dir_pages(inode);
 100         struct minix_sb_info *sbi = minix_sb(sb);
 101         unsigned chunk_size = sbi->s_dirsize;
 102         char *name;
 103         __u32 inumber;
 104
 105         pos = (pos + chunk_size-1) & ~(chunk_size-1);
 106         if (pos >= inode->i_size)
 107                 goto done;
 108
 109         for ( ; n < npages; n++, offset = 0) {
 110                 char *p, *kaddr, *limit;
 111                 struct page *page = dir_get_page(inode, n);
 112
 113                 if (IS_ERR(page))
 114                         continue;
 115                 kaddr = (char *)page_address(page);
 116                 p = kaddr+offset;
 117                 limit = kaddr + minix_last_byte(inode, n) - chunk_size;
 118                 for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
 119                         if (sbi->s_version == MINIX_V3) {
 120                                 minix3_dirent *de3 = (minix3_dirent *)p;
 121                                 name = de3->name;
 122                                 inumber = de3->inode;
 123                         } else {
 124                                 minix_dirent *de = (minix_dirent *)p;
 125                                 name = de->name;
 126                                 inumber = de->inode;
 127                         }
 128                         if (inumber) {
 129                                 int over;
 130
 131                                 unsigned l = strnlen(name, sbi->s_namelen);
 132                                 offset = p - kaddr;
 133                                 over = filldir(dirent, name, l,
 134                                         (n << PAGE_CACHE_SHIFT) | offset,
 135                                         inumber, DT_UNKNOWN);
 136                                 if (over) {
 137                                         dir_put_page(page);
 138                                         goto done;
 139                                 }
 140                         }
 141                 }
 142                 dir_put_page(page);
 143         }
 144
 145 done:
 146         filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
 147         return 0;
 148 }
 149
 150 static inline int namecompare(int len, int maxlen,
 151         const char * name, const char * buffer)
 152 {
 153         if (len < maxlen && buffer[len])
 154                 return 0;
 155         return !memcmp(name, buffer, len);
 156 }
 157
 158 /*
 159  *      minix_find_entry()
 160  *
 161  * finds an entry in the specified directory with the wanted name. It
 162  * returns the cache buffer in which the entry was found, and the entry
 163  * itself (as a parameter - res_dir). It does NOT read the inode of the
 164  * entry - you'll have to do that yourself if you want to.
 165  */
 166 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
 167 {
 168         const char * name = dentry->d_name.name;
 169         int namelen = dentry->d_name.len;
 170         struct inode * dir = dentry->d_parent->d_inode;
 171         struct super_block * sb = dir->i_sb;
 172         struct minix_sb_info * sbi = minix_sb(sb);
 173         unsigned long n;
 174         unsigned long npages = dir_pages(dir);
 175         struct page *page = NULL;
 176         char *p;
 177
 178         char *namx;
 179         __u32 inumber;
 180         *res_page = NULL;
 181
 182         for (n = 0; n < npages; n++) {
 183                 char *kaddr, *limit;
 184
 185                 page = dir_get_page(dir, n);
 186                 if (IS_ERR(page))
 187                         continue;
 188
 189                 kaddr = (char*)page_address(page);
 190                 limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
 191                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 192                         if (sbi->s_version == MINIX_V3) {
 193                                 minix3_dirent *de3 = (minix3_dirent *)p;
 194                                 namx = de3->name;
 195                                 inumber = de3->inode;
 196                         } else {
 197                                 minix_dirent *de = (minix_dirent *)p;
 198                                 namx = de->name;
 199                                 inumber = de->inode;
 200                         }
 201                         if (!inumber)
 202                                 continue;
 203                         if (namecompare(namelen, sbi->s_namelen, name, namx))
 204                                 goto found;
 205                 }
 206                 dir_put_page(page);
 207         }
 208         return NULL;
 209
 210 found:
 211         *res_page = page;
 212         return (minix_dirent *)p;
 213 }
 214
 215 int minix_add_link(struct dentry *dentry, struct inode *inode)
 216 {
 217         struct inode *dir = dentry->d_parent->d_inode;
 218         const char * name = dentry->d_name.name;
 219         int namelen = dentry->d_name.len;
 220         struct super_block * sb = dir->i_sb;
 221         struct minix_sb_info * sbi = minix_sb(sb);
 222         struct page *page = NULL;
 223         unsigned long npages = dir_pages(dir);
 224         unsigned long n;
 225         char *kaddr, *p;
 226         minix_dirent *de;
 227         minix3_dirent *de3;
 228         loff_t pos;
 229         int err;
 230         char *namx = NULL;
 231         __u32 inumber;
 232
 233         /*
 234          * We take care of directory expansion in the same loop
 235          * This code plays outside i_size, so it locks the page
 236          * to protect that region.
 237          */
 238         for (n = 0; n <= npages; n++) {
 239                 char *limit, *dir_end;
 240
 241                 page = dir_get_page(dir, n);
 242                 err = PTR_ERR(page);
 243                 if (IS_ERR(page))
 244                         goto out;
 245                 lock_page(page);
 246                 kaddr = (char*)page_address(page);
 247                 dir_end = kaddr + minix_last_byte(dir, n);
 248                 limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize;
 249                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 250                         de = (minix_dirent *)p;
 251                         de3 = (minix3_dirent *)p;
 252                         if (sbi->s_version == MINIX_V3) {
 253                                 namx = de3->name;
 254                                 inumber = de3->inode;
 255                         } else {
 256                                 namx = de->name;
 257                                 inumber = de->inode;
 258                         }
 259                         if (p == dir_end) {
 260                                 /* We hit i_size */
 261                                 if (sbi->s_version == MINIX_V3)
 262                                         de3->inode = 0;
 263                                 else
 264                                         de->inode = 0;
 265                                 goto got_it;
 266                         }
 267                         if (!inumber)
 268                                 goto got_it;
 269                         err = -EEXIST;
 270                         if (namecompare(namelen, sbi->s_namelen, name, namx))
 271                                 goto out_unlock;
 272                 }
 273                 unlock_page(page);
 274                 dir_put_page(page);
 275         }
 276         BUG();
 277         return -EINVAL;
 278
 279 got_it:
 280         pos = page_offset(page) + p - (char *)page_address(page);
 281         err = __minix_write_begin(NULL, page->mapping, pos, sbi->s_dirsize,
 282                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 283         if (err)
 284                 goto out_unlock;
 285         memcpy (namx, name, namelen);
 286         if (sbi->s_version == MINIX_V3) {
 287                 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
 288                 de3->inode = inode->i_ino;
 289         } else {
 290                 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
 291                 de->inode = inode->i_ino;
 292         }
 293         err = dir_commit_chunk(page, pos, sbi->s_dirsize);
 294         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 295         mark_inode_dirty(dir);
 296 out_put:
 297         dir_put_page(page);
 298 out:
 299         return err;
 300 out_unlock:
 301         unlock_page(page);
 302         goto out_put;
 303 }
 304
 305 int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
 306 {
 307         struct address_space *mapping = page->mapping;
 308         struct inode *inode = (struct inode*)mapping->host;
 309         char *kaddr = page_address(page);
 310         loff_t pos = page_offset(page) + (char*)de - kaddr;
 311         unsigned len = minix_sb(inode->i_sb)->s_dirsize;
 312         int err;
 313
 314         lock_page(page);
 315         err = __minix_write_begin(NULL, mapping, pos, len,
 316                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 317         if (err == 0) {
 318                 de->inode = 0;
 319                 err = dir_commit_chunk(page, pos, len);
 320         } else {
 321                 unlock_page(page);
 322         }
 323         dir_put_page(page);
 324         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 325         mark_inode_dirty(inode);
 326         return err;
 327 }
 328
 329 int minix_make_empty(struct inode *inode, struct inode *dir)
 330 {
 331         struct address_space *mapping = inode->i_mapping;
 332         struct page *page = grab_cache_page(mapping, 0);
 333         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 334         char *kaddr;
 335         int err;
 336
 337         if (!page)
 338                 return -ENOMEM;
 339         err = __minix_write_begin(NULL, mapping, 0, 2 * sbi->s_dirsize,
 340                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 341         if (err) {
 342                 unlock_page(page);
 343                 goto fail;
 344         }
 345
 346         kaddr = kmap_atomic(page, KM_USER0);
 347         memset(kaddr, 0, PAGE_CACHE_SIZE);
 348
 349         if (sbi->s_version == MINIX_V3) {
 350                 minix3_dirent *de3 = (minix3_dirent *)kaddr;
 351
 352                 de3->inode = inode->i_ino;
 353                 strcpy(de3->name, ".");
 354                 de3 = minix_next_entry(de3, sbi);
 355                 de3->inode = dir->i_ino;
 356                 strcpy(de3->name, "..");
 357         } else {
 358                 minix_dirent *de = (minix_dirent *)kaddr;
 359
 360                 de->inode = inode->i_ino;
 361                 strcpy(de->name, ".");
 362                 de = minix_next_entry(de, sbi);
 363                 de->inode = dir->i_ino;
 364                 strcpy(de->name, "..");
 365         }
 366         kunmap_atomic(kaddr, KM_USER0);
 367
 368         err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
 369 fail:
 370         page_cache_release(page);
 371         return err;
 372 }
 373
 374 /*
 375  * routine to check that the specified directory is empty (for rmdir)
 376  */
 377 int minix_empty_dir(struct inode * inode)
 378 {
 379         struct page *page = NULL;
 380         unsigned long i, npages = dir_pages(inode);
 381         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 382         char *name;
 383         __u32 inumber;
 384
 385         for (i = 0; i < npages; i++) {
 386                 char *p, *kaddr, *limit;
 387
 388                 page = dir_get_page(inode, i);
 389                 if (IS_ERR(page))
 390                         continue;
 391
 392                 kaddr = (char *)page_address(page);
 393                 limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
 394                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 395                         if (sbi->s_version == MINIX_V3) {
 396                                 minix3_dirent *de3 = (minix3_dirent *)p;
 397                                 name = de3->name;
 398                                 inumber = de3->inode;
 399                         } else {
 400                                 minix_dirent *de = (minix_dirent *)p;
 401                                 name = de->name;
 402                                 inumber = de->inode;
 403                         }
 404
 405                         if (inumber != 0) {
 406                                 /* check for . and .. */
 407                                 if (name[0] != '.')
 408                                         goto not_empty;
 409                                 if (!name[1]) {
 410                                         if (inumber != inode->i_ino)
 411                                                 goto not_empty;
 412                                 } else if (name[1] != '.')
 413                                         goto not_empty;
 414                                 else if (name[2])
 415                                         goto not_empty;
 416                         }
 417                 }
 418                 dir_put_page(page);
 419         }
 420         return 1;
 421
 422 not_empty:
 423         dir_put_page(page);
 424         return 0;
 425 }
 426
 427 /* Releases the page */
 428 void minix_set_link(struct minix_dir_entry *de, struct page *page,
 429         struct inode *inode)
 430 {
 431         struct address_space *mapping = page->mapping;
 432         struct inode *dir = mapping->host;
 433         struct minix_sb_info *sbi = minix_sb(dir->i_sb);
 434         loff_t pos = page_offset(page) +
 435                         (char *)de-(char*)page_address(page);
 436         int err;
 437
 438         lock_page(page);
 439
 440         err = __minix_write_begin(NULL, mapping, pos, sbi->s_dirsize,
 441                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 442         if (err == 0) {
 443                 de->inode = inode->i_ino;
 444                 err = dir_commit_chunk(page, pos, sbi->s_dirsize);
 445         } else {
 446                 unlock_page(page);
 447         }
 448         dir_put_page(page);
 449         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 450         mark_inode_dirty(dir);
 451 }
 452
 453 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
 454 {
 455         struct page *page = dir_get_page(dir, 0);
 456         struct minix_sb_info *sbi = minix_sb(dir->i_sb);
 457         struct minix_dir_entry *de = NULL;
 458
 459         if (!IS_ERR(page)) {
 460                 de = minix_next_entry(page_address(page), sbi);
 461                 *p = page;
 462         }
 463         return de;
 464 }
 465
 466 ino_t minix_inode_by_name(struct dentry *dentry)
 467 {
 468         struct page *page;
 469         struct minix_dir_entry *de = minix_find_entry(dentry, &page);
 470         ino_t res = 0;
 471
 472         if (de) {
 473                 res = de->inode;
 474                 dir_put_page(page);
 475         }
 476         return res;
 477 }