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/smp_lock.h>
  15 #include <linux/swap.h>
  16
  17 typedef struct minix_dir_entry minix_dirent;
  18 typedef struct minix3_dir_entry minix3_dirent;
  19
  20 static int minix_readdir(struct file *, void *, filldir_t);
  21
  22 const struct file_operations minix_dir_operations = {
  23         .read           = generic_read_dir,
  24         .readdir        = minix_readdir,
  25         .fsync          = minix_sync_file,
  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         lock_kernel();
 106
 107         pos = (pos + chunk_size-1) & ~(chunk_size-1);
 108         if (pos >= inode->i_size)
 109                 goto done;
 110
 111         for ( ; n < npages; n++, offset = 0) {
 112                 char *p, *kaddr, *limit;
 113                 struct page *page = dir_get_page(inode, n);
 114
 115                 if (IS_ERR(page))
 116                         continue;
 117                 kaddr = (char *)page_address(page);
 118                 p = kaddr+offset;
 119                 limit = kaddr + minix_last_byte(inode, n) - chunk_size;
 120                 for ( ; p <= limit; p = minix_next_entry(p, sbi)) {
 121                         if (sbi->s_version == MINIX_V3) {
 122                                 minix3_dirent *de3 = (minix3_dirent *)p;
 123                                 name = de3->name;
 124                                 inumber = de3->inode;
 125                         } else {
 126                                 minix_dirent *de = (minix_dirent *)p;
 127                                 name = de->name;
 128                                 inumber = de->inode;
 129                         }
 130                         if (inumber) {
 131                                 int over;
 132
 133                                 unsigned l = strnlen(name, sbi->s_namelen);
 134                                 offset = p - kaddr;
 135                                 over = filldir(dirent, name, l,
 136                                         (n << PAGE_CACHE_SHIFT) | offset,
 137                                         inumber, DT_UNKNOWN);
 138                                 if (over) {
 139                                         dir_put_page(page);
 140                                         goto done;
 141                                 }
 142                         }
 143                 }
 144                 dir_put_page(page);
 145         }
 146
 147 done:
 148         filp->f_pos = (n << PAGE_CACHE_SHIFT) | offset;
 149         unlock_kernel();
 150         return 0;
 151 }
 152
 153 static inline int namecompare(int len, int maxlen,
 154         const char * name, const char * buffer)
 155 {
 156         if (len < maxlen && buffer[len])
 157                 return 0;
 158         return !memcmp(name, buffer, len);
 159 }
 160
 161 /*
 162  *      minix_find_entry()
 163  *
 164  * finds an entry in the specified directory with the wanted name. It
 165  * returns the cache buffer in which the entry was found, and the entry
 166  * itself (as a parameter - res_dir). It does NOT read the inode of the
 167  * entry - you'll have to do that yourself if you want to.
 168  */
 169 minix_dirent *minix_find_entry(struct dentry *dentry, struct page **res_page)
 170 {
 171         const char * name = dentry->d_name.name;
 172         int namelen = dentry->d_name.len;
 173         struct inode * dir = dentry->d_parent->d_inode;
 174         struct super_block * sb = dir->i_sb;
 175         struct minix_sb_info * sbi = minix_sb(sb);
 176         unsigned long n;
 177         unsigned long npages = dir_pages(dir);
 178         struct page *page = NULL;
 179         char *p;
 180
 181         char *namx;
 182         __u32 inumber;
 183         *res_page = NULL;
 184
 185         for (n = 0; n < npages; n++) {
 186                 char *kaddr, *limit;
 187
 188                 page = dir_get_page(dir, n);
 189                 if (IS_ERR(page))
 190                         continue;
 191
 192                 kaddr = (char*)page_address(page);
 193                 limit = kaddr + minix_last_byte(dir, n) - sbi->s_dirsize;
 194                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 195                         if (sbi->s_version == MINIX_V3) {
 196                                 minix3_dirent *de3 = (minix3_dirent *)p;
 197                                 namx = de3->name;
 198                                 inumber = de3->inode;
 199                         } else {
 200                                 minix_dirent *de = (minix_dirent *)p;
 201                                 namx = de->name;
 202                                 inumber = de->inode;
 203                         }
 204                         if (!inumber)
 205                                 continue;
 206                         if (namecompare(namelen, sbi->s_namelen, name, namx))
 207                                 goto found;
 208                 }
 209                 dir_put_page(page);
 210         }
 211         return NULL;
 212
 213 found:
 214         *res_page = page;
 215         return (minix_dirent *)p;
 216 }
 217
 218 int minix_add_link(struct dentry *dentry, struct inode *inode)
 219 {
 220         struct inode *dir = dentry->d_parent->d_inode;
 221         const char * name = dentry->d_name.name;
 222         int namelen = dentry->d_name.len;
 223         struct super_block * sb = dir->i_sb;
 224         struct minix_sb_info * sbi = minix_sb(sb);
 225         struct page *page = NULL;
 226         unsigned long npages = dir_pages(dir);
 227         unsigned long n;
 228         char *kaddr, *p;
 229         minix_dirent *de;
 230         minix3_dirent *de3;
 231         loff_t pos;
 232         int err;
 233         char *namx = NULL;
 234         __u32 inumber;
 235
 236         /*
 237          * We take care of directory expansion in the same loop
 238          * This code plays outside i_size, so it locks the page
 239          * to protect that region.
 240          */
 241         for (n = 0; n <= npages; n++) {
 242                 char *limit, *dir_end;
 243
 244                 page = dir_get_page(dir, n);
 245                 err = PTR_ERR(page);
 246                 if (IS_ERR(page))
 247                         goto out;
 248                 lock_page(page);
 249                 kaddr = (char*)page_address(page);
 250                 dir_end = kaddr + minix_last_byte(dir, n);
 251                 limit = kaddr + PAGE_CACHE_SIZE - sbi->s_dirsize;
 252                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 253                         de = (minix_dirent *)p;
 254                         de3 = (minix3_dirent *)p;
 255                         if (sbi->s_version == MINIX_V3) {
 256                                 namx = de3->name;
 257                                 inumber = de3->inode;
 258                         } else {
 259                                 namx = de->name;
 260                                 inumber = de->inode;
 261                         }
 262                         if (p == dir_end) {
 263                                 /* We hit i_size */
 264                                 if (sbi->s_version == MINIX_V3)
 265                                         de3->inode = 0;
 266                                 else
 267                                         de->inode = 0;
 268                                 goto got_it;
 269                         }
 270                         if (!inumber)
 271                                 goto got_it;
 272                         err = -EEXIST;
 273                         if (namecompare(namelen, sbi->s_namelen, name, namx))
 274                                 goto out_unlock;
 275                 }
 276                 unlock_page(page);
 277                 dir_put_page(page);
 278         }
 279         BUG();
 280         return -EINVAL;
 281
 282 got_it:
 283         pos = page_offset(page) + p - (char *)page_address(page);
 284         err = __minix_write_begin(NULL, page->mapping, pos, sbi->s_dirsize,
 285                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 286         if (err)
 287                 goto out_unlock;
 288         memcpy (namx, name, namelen);
 289         if (sbi->s_version == MINIX_V3) {
 290                 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 4);
 291                 de3->inode = inode->i_ino;
 292         } else {
 293                 memset (namx + namelen, 0, sbi->s_dirsize - namelen - 2);
 294                 de->inode = inode->i_ino;
 295         }
 296         err = dir_commit_chunk(page, pos, sbi->s_dirsize);
 297         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 298         mark_inode_dirty(dir);
 299 out_put:
 300         dir_put_page(page);
 301 out:
 302         return err;
 303 out_unlock:
 304         unlock_page(page);
 305         goto out_put;
 306 }
 307
 308 int minix_delete_entry(struct minix_dir_entry *de, struct page *page)
 309 {
 310         struct address_space *mapping = page->mapping;
 311         struct inode *inode = (struct inode*)mapping->host;
 312         char *kaddr = page_address(page);
 313         loff_t pos = page_offset(page) + (char*)de - kaddr;
 314         unsigned len = minix_sb(inode->i_sb)->s_dirsize;
 315         int err;
 316
 317         lock_page(page);
 318         err = __minix_write_begin(NULL, mapping, pos, len,
 319                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 320         if (err == 0) {
 321                 de->inode = 0;
 322                 err = dir_commit_chunk(page, pos, len);
 323         } else {
 324                 unlock_page(page);
 325         }
 326         dir_put_page(page);
 327         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 328         mark_inode_dirty(inode);
 329         return err;
 330 }
 331
 332 int minix_make_empty(struct inode *inode, struct inode *dir)
 333 {
 334         struct address_space *mapping = inode->i_mapping;
 335         struct page *page = grab_cache_page(mapping, 0);
 336         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 337         char *kaddr;
 338         int err;
 339
 340         if (!page)
 341                 return -ENOMEM;
 342         err = __minix_write_begin(NULL, mapping, 0, 2 * sbi->s_dirsize,
 343                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 344         if (err) {
 345                 unlock_page(page);
 346                 goto fail;
 347         }
 348
 349         kaddr = kmap_atomic(page, KM_USER0);
 350         memset(kaddr, 0, PAGE_CACHE_SIZE);
 351
 352         if (sbi->s_version == MINIX_V3) {
 353                 minix3_dirent *de3 = (minix3_dirent *)kaddr;
 354
 355                 de3->inode = inode->i_ino;
 356                 strcpy(de3->name, ".");
 357                 de3 = minix_next_entry(de3, sbi);
 358                 de3->inode = dir->i_ino;
 359                 strcpy(de3->name, "..");
 360         } else {
 361                 minix_dirent *de = (minix_dirent *)kaddr;
 362
 363                 de->inode = inode->i_ino;
 364                 strcpy(de->name, ".");
 365                 de = minix_next_entry(de, sbi);
 366                 de->inode = dir->i_ino;
 367                 strcpy(de->name, "..");
 368         }
 369         kunmap_atomic(kaddr, KM_USER0);
 370
 371         err = dir_commit_chunk(page, 0, 2 * sbi->s_dirsize);
 372 fail:
 373         page_cache_release(page);
 374         return err;
 375 }
 376
 377 /*
 378  * routine to check that the specified directory is empty (for rmdir)
 379  */
 380 int minix_empty_dir(struct inode * inode)
 381 {
 382         struct page *page = NULL;
 383         unsigned long i, npages = dir_pages(inode);
 384         struct minix_sb_info *sbi = minix_sb(inode->i_sb);
 385         char *name;
 386         __u32 inumber;
 387
 388         for (i = 0; i < npages; i++) {
 389                 char *p, *kaddr, *limit;
 390
 391                 page = dir_get_page(inode, i);
 392                 if (IS_ERR(page))
 393                         continue;
 394
 395                 kaddr = (char *)page_address(page);
 396                 limit = kaddr + minix_last_byte(inode, i) - sbi->s_dirsize;
 397                 for (p = kaddr; p <= limit; p = minix_next_entry(p, sbi)) {
 398                         if (sbi->s_version == MINIX_V3) {
 399                                 minix3_dirent *de3 = (minix3_dirent *)p;
 400                                 name = de3->name;
 401                                 inumber = de3->inode;
 402                         } else {
 403                                 minix_dirent *de = (minix_dirent *)p;
 404                                 name = de->name;
 405                                 inumber = de->inode;
 406                         }
 407
 408                         if (inumber != 0) {
 409                                 /* check for . and .. */
 410                                 if (name[0] != '.')
 411                                         goto not_empty;
 412                                 if (!name[1]) {
 413                                         if (inumber != inode->i_ino)
 414                                                 goto not_empty;
 415                                 } else if (name[1] != '.')
 416                                         goto not_empty;
 417                                 else if (name[2])
 418                                         goto not_empty;
 419                         }
 420                 }
 421                 dir_put_page(page);
 422         }
 423         return 1;
 424
 425 not_empty:
 426         dir_put_page(page);
 427         return 0;
 428 }
 429
 430 /* Releases the page */
 431 void minix_set_link(struct minix_dir_entry *de, struct page *page,
 432         struct inode *inode)
 433 {
 434         struct address_space *mapping = page->mapping;
 435         struct inode *dir = mapping->host;
 436         struct minix_sb_info *sbi = minix_sb(dir->i_sb);
 437         loff_t pos = page_offset(page) +
 438                         (char *)de-(char*)page_address(page);
 439         int err;
 440
 441         lock_page(page);
 442
 443         err = __minix_write_begin(NULL, mapping, pos, sbi->s_dirsize,
 444                                         AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
 445         if (err == 0) {
 446                 de->inode = inode->i_ino;
 447                 err = dir_commit_chunk(page, pos, sbi->s_dirsize);
 448         } else {
 449                 unlock_page(page);
 450         }
 451         dir_put_page(page);
 452         dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
 453         mark_inode_dirty(dir);
 454 }
 455
 456 struct minix_dir_entry * minix_dotdot (struct inode *dir, struct page **p)
 457 {
 458         struct page *page = dir_get_page(dir, 0);
 459         struct minix_sb_info *sbi = minix_sb(dir->i_sb);
 460         struct minix_dir_entry *de = NULL;
 461
 462         if (!IS_ERR(page)) {
 463                 de = minix_next_entry(page_address(page), sbi);
 464                 *p = page;
 465         }
 466         return de;
 467 }
 468
 469 ino_t minix_inode_by_name(struct dentry *dentry)
 470 {
 471         struct page *page;
 472         struct minix_dir_entry *de = minix_find_entry(dentry, &page);
 473         ino_t res = 0;
 474
 475         if (de) {
 476                 res = de->inode;
 477                 dir_put_page(page);
 478         }
 479         return res;
 480 }