fs/ext2/namei.c

/* */
This source file includes following definitions.
ext2_match
ext2_find_entry
ext2_lookup
ext2_add_entry
ext2_delete_entry
ext2_create
ext2_mknod
ext2_mkdir
empty_dir
ext2_rmdir
ext2_unlink
ext2_symlink
ext2_link
subdir
do_ext2_rename
ext2_rename
   1 /*
   2  *  linux/fs/ext2/namei.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/namei.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  */
  15 
  16 #include <asm/segment.h>
  17 
  18 #include <linux/errno.h>
  19 #include <linux/fs.h>
  20 #include <linux/ext2_fs.h>
  21 #include <linux/fcntl.h>
  22 #include <linux/sched.h>
  23 #include <linux/stat.h>
  24 #include <linux/string.h>
  25 #include <linux/locks.h>
  26 
  27 /*
  28  * comment out this line if you want names > EXT2_NAME_LEN chars to be
  29  * truncated. Else they will be disallowed.
  30  */
  31 /* #define NO_TRUNCATE */
  32 
  33 /*
  34  * define how far ahead to read directories while searching them.
  35  */
  36 #define NAMEI_RA_CHUNKS  2
  37 #define NAMEI_RA_BLOCKS  4
  38 #define NAMEI_RA_SIZE        (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
  39 #define NAMEI_RA_INDEX(c,b)  (((c) * NAMEI_RA_BLOCKS) + (b))
  40 
  41 /*
  42  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
  43  */
  44 static int ext2_match (int len, const char * const name,
     /*  */
  45                        struct ext2_dir_entry * de)
  46 {
  47         if (!de || !de->inode || len > EXT2_NAME_LEN)
  48                 return 0;
  49         /*
  50          * "" means "." ---> so paths like "/usr/lib//libc.a" work
  51          */
  52         if (!len && de->name_len == 1 && (de->name[0] == '.') &&
  53            (de->name[1] == '\0'))
  54                 return 1;
  55         if (len != de->name_len)
  56                 return 0;
  57         return !memcmp(name, de->name, len);
  58 }
  59 
  60 /*
  61  *      ext2_find_entry()
  62  *
  63  * finds an entry in the specified directory with the wanted name. It
  64  * returns the cache buffer in which the entry was found, and the entry
  65  * itself (as a parameter - res_dir). It does NOT read the inode of the
  66  * entry - you'll have to do that yourself if you want to.
  67  */
  68 static struct buffer_head * ext2_find_entry (struct inode * dir,
     /*  */
  69                                              const char * const name, int namelen,
  70                                              struct ext2_dir_entry ** res_dir)
  71 {
  72         struct super_block * sb;
  73         struct buffer_head * bh_use[NAMEI_RA_SIZE];
  74         struct buffer_head * bh_read[NAMEI_RA_SIZE];
  75         unsigned long offset;
  76         int block, toread, i, err;
  77 
  78         *res_dir = NULL;
  79         if (!dir)
  80                 return NULL;
  81         sb = dir->i_sb;
  82 
  83 #ifdef NO_TRUNCATE
  84         if (namelen > EXT2_NAME_LEN)
  85                 return NULL;
  86 #else
  87         if (namelen > EXT2_NAME_LEN)
  88                 namelen = EXT2_NAME_LEN;
  89 #endif
  90 
  91         memset (bh_use, 0, sizeof (bh_use));
  92         toread = 0;
  93         for (block = 0; block < NAMEI_RA_SIZE; ++block) {
  94                 struct buffer_head * bh;
  95 
  96                 if ((block << EXT2_BLOCK_SIZE_BITS (sb)) >= dir->i_size)
  97                         break;
  98                 bh = ext2_getblk (dir, block, 0, &err);
  99                 bh_use[block] = bh;
 100                 if (bh && !buffer_uptodate(bh))
 101                         bh_read[toread++] = bh;
 102         }
 103 
 104         for (block = 0, offset = 0; offset < dir->i_size; block++) {
 105                 struct buffer_head * bh;
 106                 struct ext2_dir_entry * de;
 107                 char * dlimit;
 108 
 109                 if ((block % NAMEI_RA_BLOCKS) == 0 && toread) {
 110                         ll_rw_block (READ, toread, bh_read);
 111                         toread = 0;
 112                 }
 113                 bh = bh_use[block % NAMEI_RA_SIZE];
 114                 if (!bh) {
 115                         ext2_error (sb, "ext2_find_entry",
 116                                     "directory #%lu contains a hole at offset %lu",
 117                                     dir->i_ino, offset);
 118                         offset += sb->s_blocksize;
 119                         continue;
 120                 }
 121                 wait_on_buffer (bh);
 122                 if (!buffer_uptodate(bh)) {
 123                         /*
 124                          * read error: all bets are off
 125                          */
 126                         break;
 127                 }
 128 
 129                 de = (struct ext2_dir_entry *) bh->b_data;
 130                 dlimit = bh->b_data + sb->s_blocksize;
 131                 while ((char *) de < dlimit) {
 132                         if (!ext2_check_dir_entry ("ext2_find_entry", dir,
 133                                                    de, bh, offset))
 134                                 goto failure;
 135                         if (de->inode != 0 && ext2_match (namelen, name, de)) {
 136                                 for (i = 0; i < NAMEI_RA_SIZE; ++i) {
 137                                         if (bh_use[i] != bh)
 138                                                 brelse (bh_use[i]);
 139                                 }
 140                                 *res_dir = de;
 141                                 return bh;
 142                         }
 143                         offset += de->rec_len;
 144                         de = (struct ext2_dir_entry *)
 145                                 ((char *) de + de->rec_len);
 146                 }
 147 
 148                 brelse (bh);
 149                 if (((block + NAMEI_RA_SIZE) << EXT2_BLOCK_SIZE_BITS (sb)) >=
 150                     dir->i_size)
 151                         bh = NULL;
 152                 else
 153                         bh = ext2_getblk (dir, block + NAMEI_RA_SIZE, 0, &err);
 154                 bh_use[block % NAMEI_RA_SIZE] = bh;
 155                 if (bh && !buffer_uptodate(bh))
 156                         bh_read[toread++] = bh;
 157         }
 158 
 159 failure:
 160         for (i = 0; i < NAMEI_RA_SIZE; ++i)
 161                 brelse (bh_use[i]);
 162         return NULL;
 163 }
 164 
 165 int ext2_lookup (struct inode * dir, const char * name, int len,
     /*  */
 166                  struct inode ** result)
 167 {
 168         unsigned long ino;
 169         struct ext2_dir_entry * de;
 170         struct buffer_head * bh;
 171 
 172         *result = NULL;
 173         if (!dir)
 174                 return -ENOENT;
 175         if (!S_ISDIR(dir->i_mode)) {
 176                 iput (dir);
 177                 return -ENOENT;
 178         }
 179         if (dcache_lookup(dir, name, len, &ino)) {
 180                 if (!ino) {
 181                         iput(dir);
 182                         return -ENOENT;
 183                 }
 184                 if (!(*result = iget (dir->i_sb, ino))) {
 185                         iput (dir);
 186                         return -EACCES;
 187                 }
 188                 iput (dir);
 189                 return 0;
 190         }
 191         ino = dir->i_version;
 192         if (!(bh = ext2_find_entry (dir, name, len, &de))) {
 193                 if (ino == dir->i_version)
 194                         dcache_add(dir, name, len, 0);
 195                 iput (dir);
 196                 return -ENOENT;
 197         }
 198         ino = de->inode;
 199         dcache_add(dir, name, len, ino);
 200         brelse (bh);
 201         if (!(*result = iget (dir->i_sb, ino))) {
 202                 iput (dir);
 203                 return -EACCES;
 204         }
 205         iput (dir);
 206         return 0;
 207 }
 208 
 209 /*
 210  *      ext2_add_entry()
 211  *
 212  * adds a file entry to the specified directory, using the same
 213  * semantics as ext2_find_entry(). It returns NULL if it failed.
 214  *
 215  * NOTE!! The inode part of 'de' is left at 0 - which means you
 216  * may not sleep between calling this and putting something into
 217  * the entry, as someone else might have used it while you slept.
 218  */
 219 static struct buffer_head * ext2_add_entry (struct inode * dir,
     /*  */
 220                                             const char * name, int namelen,
 221                                             struct ext2_dir_entry ** res_dir,
 222                                             int *err)
 223 {
 224         unsigned long offset;
 225         unsigned short rec_len;
 226         struct buffer_head * bh;
 227         struct ext2_dir_entry * de, * de1;
 228         struct super_block * sb;
 229 
 230         *err = -EINVAL;
 231         *res_dir = NULL;
 232         if (!dir)
 233                 return NULL;
 234         sb = dir->i_sb;
 235 #ifdef NO_TRUNCATE
 236         if (namelen > EXT2_NAME_LEN)
 237                 return NULL;
 238 #else
 239         if (namelen > EXT2_NAME_LEN)
 240                 namelen = EXT2_NAME_LEN;
 241 #endif
 242         if (!namelen)
 243                 return NULL;
 244         /*
 245          * Is this a busy deleted directory?  Can't create new files if so
 246          */
 247         if (dir->i_size == 0)
 248         {
 249                 *err = -ENOENT;
 250                 return NULL;
 251         }
 252         bh = ext2_bread (dir, 0, 0, err);
 253         if (!bh)
 254                 return NULL;
 255         rec_len = EXT2_DIR_REC_LEN(namelen);
 256         offset = 0;
 257         de = (struct ext2_dir_entry *) bh->b_data;
 258         *err = -ENOSPC;
 259         while (1) {
 260                 if ((char *)de >= sb->s_blocksize + bh->b_data) {
 261                         brelse (bh);
 262                         bh = NULL;
 263                         bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, err);
 264                         if (!bh)
 265                                 return NULL;
 266                         if (dir->i_size <= offset) {
 267                                 if (dir->i_size == 0) {
 268                                         *err = -ENOENT;
 269                                         return NULL;
 270                                 }
 271 
 272                                 ext2_debug ("creating next block\n");
 273 
 274                                 de = (struct ext2_dir_entry *) bh->b_data;
 275                                 de->inode = 0;
 276                                 de->rec_len = sb->s_blocksize;
 277                                 dir->i_size = offset + sb->s_blocksize;
 278                                 dir->i_dirt = 1;
 279                         } else {
 280 
 281                                 ext2_debug ("skipping to next block\n");
 282 
 283                                 de = (struct ext2_dir_entry *) bh->b_data;
 284                         }
 285                 }
 286                 if (!ext2_check_dir_entry ("ext2_add_entry", dir, de, bh,
 287                                            offset)) {
 288                         *err = -ENOENT;
 289                         brelse (bh);
 290                         return NULL;
 291                 }
 292                 if (de->inode != 0 && ext2_match (namelen, name, de)) {
 293                                 *err = -EEXIST;
 294                                 brelse (bh);
 295                                 return NULL;
 296                 }
 297                 if ((de->inode == 0 && de->rec_len >= rec_len) ||
 298                     (de->rec_len >= EXT2_DIR_REC_LEN(de->name_len) + rec_len)) {
 299                         offset += de->rec_len;
 300                         if (de->inode) {
 301                                 de1 = (struct ext2_dir_entry *) ((char *) de +
 302                                         EXT2_DIR_REC_LEN(de->name_len));
 303                                 de1->rec_len = de->rec_len -
 304                                         EXT2_DIR_REC_LEN(de->name_len);
 305                                 de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 306                                 de = de1;
 307                         }
 308                         de->inode = 0;
 309                         de->name_len = namelen;
 310                         memcpy (de->name, name, namelen);
 311                         /*
 312                          * XXX shouldn't update any times until successful
 313                          * completion of syscall, but too many callers depend
 314                          * on this.
 315                          *
 316                          * XXX similarly, too many callers depend on
 317                          * ext2_new_inode() setting the times, but error
 318                          * recovery deletes the inode, so the worst that can
 319                          * happen is that the times are slightly out of date
 320                          * and/or different from the directory change time.
 321                          */
 322                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 323                         dir->i_dirt = 1;
 324                         dir->i_version = ++event;
 325                         mark_buffer_dirty(bh, 1);
 326                         *res_dir = de;
 327                         *err = 0;
 328                         return bh;
 329                 }
 330                 offset += de->rec_len;
 331                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 332         }
 333         brelse (bh);
 334         return NULL;
 335 }
 336 
 337 /*
 338  * ext2_delete_entry deletes a directory entry by merging it with the
 339  * previous entry
 340  */
 341 static int ext2_delete_entry (struct ext2_dir_entry * dir,
     /*  */
 342                               struct buffer_head * bh)
 343 {
 344         struct ext2_dir_entry * de, * pde;
 345         int i;
 346 
 347         i = 0;
 348         pde = NULL;
 349         de = (struct ext2_dir_entry *) bh->b_data;
 350         while (i < bh->b_size) {
 351                 if (!ext2_check_dir_entry ("ext2_delete_entry", NULL, 
 352                                            de, bh, i))
 353                         return -EIO;
 354                 if (de == dir)  {
 355                         if (pde)
 356                                 pde->rec_len += dir->rec_len;
 357                         dir->inode = 0;
 358                         return 0;
 359                 }
 360                 i += de->rec_len;
 361                 pde = de;
 362                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 363         }
 364         return -ENOENT;
 365 }
 366 
 367 int ext2_create (struct inode * dir,const char * name, int len, int mode,
     /*  */
 368                  struct inode ** result)
 369 {
 370         struct inode * inode;
 371         struct buffer_head * bh;
 372         struct ext2_dir_entry * de;
 373         int err;
 374 
 375         *result = NULL;
 376         if (!dir)
 377                 return -ENOENT;
 378         inode = ext2_new_inode (dir, mode, &err);
 379         if (!inode) {
 380                 iput (dir);
 381                 return err;
 382         }
 383         inode->i_op = &ext2_file_inode_operations;
 384         inode->i_mode = mode;
 385         inode->i_dirt = 1;
 386         bh = ext2_add_entry (dir, name, len, &de, &err);
 387         if (!bh) {
 388                 inode->i_nlink--;
 389                 inode->i_dirt = 1;
 390                 iput (inode);
 391                 iput (dir);
 392                 return err;
 393         }
 394         de->inode = inode->i_ino;
 395         dir->i_version = ++event;
 396         dcache_add(dir, de->name, de->name_len, de->inode);
 397         mark_buffer_dirty(bh, 1);
 398         if (IS_SYNC(dir)) {
 399                 ll_rw_block (WRITE, 1, &bh);
 400                 wait_on_buffer (bh);
 401         }
 402         brelse (bh);
 403         iput (dir);
 404         *result = inode;
 405         return 0;
 406 }
 407 
 408 int ext2_mknod (struct inode * dir, const char * name, int len, int mode,
     /*  */
 409                 int rdev)
 410 {
 411         struct inode * inode;
 412         struct buffer_head * bh;
 413         struct ext2_dir_entry * de;
 414         int err;
 415 
 416         if (!dir)
 417                 return -ENOENT;
 418         bh = ext2_find_entry (dir, name, len, &de);
 419         if (bh) {
 420                 brelse (bh);
 421                 iput (dir);
 422                 return -EEXIST;
 423         }
 424         inode = ext2_new_inode (dir, mode, &err);
 425         if (!inode) {
 426                 iput (dir);
 427                 return err;
 428         }
 429         inode->i_uid = current->fsuid;
 430         inode->i_mode = mode;
 431         inode->i_op = NULL;
 432         if (S_ISREG(inode->i_mode))
 433                 inode->i_op = &ext2_file_inode_operations;
 434         else if (S_ISDIR(inode->i_mode)) {
 435                 inode->i_op = &ext2_dir_inode_operations;
 436                 if (dir->i_mode & S_ISGID)
 437                         inode->i_mode |= S_ISGID;
 438         }
 439         else if (S_ISLNK(inode->i_mode))
 440                 inode->i_op = &ext2_symlink_inode_operations;
 441         else if (S_ISCHR(inode->i_mode))
 442                 inode->i_op = &chrdev_inode_operations;
 443         else if (S_ISBLK(inode->i_mode))
 444                 inode->i_op = &blkdev_inode_operations;
 445         else if (S_ISFIFO(inode->i_mode)) 
 446                 init_fifo(inode);
 447         if (S_ISBLK(mode) || S_ISCHR(mode))
 448                 inode->i_rdev = to_kdev_t(rdev);
 449         inode->i_dirt = 1;
 450         bh = ext2_add_entry (dir, name, len, &de, &err);
 451         if (!bh) {
 452                 inode->i_nlink--;
 453                 inode->i_dirt = 1;
 454                 iput (inode);
 455                 iput (dir);
 456                 return err;
 457         }
 458         de->inode = inode->i_ino;
 459         dir->i_version = ++event;
 460         dcache_add(dir, de->name, de->name_len, de->inode);
 461         mark_buffer_dirty(bh, 1);
 462         if (IS_SYNC(dir)) {
 463                 ll_rw_block (WRITE, 1, &bh);
 464                 wait_on_buffer (bh);
 465         }
 466         brelse (bh);
 467         iput (dir);
 468         iput (inode);
 469         return 0;
 470 }
 471 
 472 int ext2_mkdir (struct inode * dir, const char * name, int len, int mode)
     /*  */
 473 {
 474         struct inode * inode;
 475         struct buffer_head * bh, * dir_block;
 476         struct ext2_dir_entry * de;
 477         int err;
 478 
 479         if (!dir)
 480                 return -ENOENT;
 481         bh = ext2_find_entry (dir, name, len, &de);
 482         if (bh) {
 483                 brelse (bh);
 484                 iput (dir);
 485                 return -EEXIST;
 486         }
 487         if (dir->i_nlink >= EXT2_LINK_MAX) {
 488                 iput (dir);
 489                 return -EMLINK;
 490         }
 491         inode = ext2_new_inode (dir, S_IFDIR, &err);
 492         if (!inode) {
 493                 iput (dir);
 494                 return err;
 495         }
 496         inode->i_op = &ext2_dir_inode_operations;
 497         inode->i_size = inode->i_sb->s_blocksize;
 498         dir_block = ext2_bread (inode, 0, 1, &err);
 499         if (!dir_block) {
 500                 iput (dir);
 501                 inode->i_nlink--;
 502                 inode->i_dirt = 1;
 503                 iput (inode);
 504                 return err;
 505         }
 506         inode->i_blocks = inode->i_sb->s_blocksize / 512;
 507         de = (struct ext2_dir_entry *) dir_block->b_data;
 508         de->inode = inode->i_ino;
 509         de->name_len = 1;
 510         de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 511         strcpy (de->name, ".");
 512         de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 513         de->inode = dir->i_ino;
 514         de->rec_len = inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1);
 515         de->name_len = 2;
 516         strcpy (de->name, "..");
 517         inode->i_nlink = 2;
 518         mark_buffer_dirty(dir_block, 1);
 519         brelse (dir_block);
 520         inode->i_mode = S_IFDIR | (mode & S_IRWXUGO & ~current->fs->umask);
 521         if (dir->i_mode & S_ISGID)
 522                 inode->i_mode |= S_ISGID;
 523         inode->i_dirt = 1;
 524         bh = ext2_add_entry (dir, name, len, &de, &err);
 525         if (!bh) {
 526                 iput (dir);
 527                 inode->i_nlink = 0;
 528                 inode->i_dirt = 1;
 529                 iput (inode);
 530                 return err;
 531         }
 532         de->inode = inode->i_ino;
 533         dir->i_version = ++event;
 534         dcache_add(dir, de->name, de->name_len, de->inode);
 535         mark_buffer_dirty(bh, 1);
 536         if (IS_SYNC(dir)) {
 537                 ll_rw_block (WRITE, 1, &bh);
 538                 wait_on_buffer (bh);
 539         }
 540         dir->i_nlink++;
 541         dir->i_dirt = 1;
 542         iput (dir);
 543         iput (inode);
 544         brelse (bh);
 545         return 0;
 546 }
 547 
 548 /*
 549  * routine to check that the specified directory is empty (for rmdir)
 550  */
 551 static int empty_dir (struct inode * inode)
     /*  */
 552 {
 553         unsigned long offset;
 554         struct buffer_head * bh;
 555         struct ext2_dir_entry * de, * de1;
 556         struct super_block * sb;
 557         int err;
 558 
 559         sb = inode->i_sb;
 560         if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
 561             !(bh = ext2_bread (inode, 0, 0, &err))) {
 562                 ext2_warning (inode->i_sb, "empty_dir",
 563                               "bad directory (dir #%lu) - no data block",
 564                               inode->i_ino);
 565                 return 1;
 566         }
 567         de = (struct ext2_dir_entry *) bh->b_data;
 568         de1 = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 569         if (de->inode != inode->i_ino || !de1->inode || 
 570             strcmp (".", de->name) || strcmp ("..", de1->name)) {
 571                 ext2_warning (inode->i_sb, "empty_dir",
 572                               "bad directory (dir #%lu) - no `.' or `..'",
 573                               inode->i_ino);
 574                 return 1;
 575         }
 576         offset = de->rec_len + de1->rec_len;
 577         de = (struct ext2_dir_entry *) ((char *) de1 + de1->rec_len);
 578         while (offset < inode->i_size ) {
 579                 if ((void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
 580                         brelse (bh);
 581                         bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
 582                         if (!bh) {
 583                                 ext2_error (sb, "empty_dir",
 584                                             "directory #%lu contains a hole at offset %lu",
 585                                             inode->i_ino, offset);
 586                                 offset += sb->s_blocksize;
 587                                 continue;
 588                         }
 589                         de = (struct ext2_dir_entry *) bh->b_data;
 590                 }
 591                 if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
 592                                            offset)) {
 593                         brelse (bh);
 594                         return 1;
 595                 }
 596                 if (de->inode) {
 597                         brelse (bh);
 598                         return 0;
 599                 }
 600                 offset += de->rec_len;
 601                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 602         }
 603         brelse (bh);
 604         return 1;
 605 }
 606 
 607 int ext2_rmdir (struct inode * dir, const char * name, int len)
     /*  */
 608 {
 609         int retval;
 610         struct inode * inode;
 611         struct buffer_head * bh;
 612         struct ext2_dir_entry * de;
 613 
 614 repeat:
 615         if (!dir)
 616                 return -ENOENT;
 617         inode = NULL;
 618         bh = ext2_find_entry (dir, name, len, &de);
 619         retval = -ENOENT;
 620         if (!bh)
 621                 goto end_rmdir;
 622         retval = -EPERM;
 623         if (!(inode = iget (dir->i_sb, de->inode)))
 624                 goto end_rmdir;
 625         if (inode->i_sb->dq_op)
 626                 inode->i_sb->dq_op->initialize (inode, -1);
 627         if (inode->i_dev != dir->i_dev)
 628                 goto end_rmdir;
 629         if (de->inode != inode->i_ino) {
 630                 iput(inode);
 631                 brelse(bh);
 632                 current->counter = 0;
 633                 schedule();
 634                 goto repeat;
 635         }
 636         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 637             current->fsuid != inode->i_uid &&
 638             current->fsuid != dir->i_uid)
 639                 goto end_rmdir;
 640         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 641                 goto end_rmdir;
 642         if (!S_ISDIR(inode->i_mode)) {
 643                 retval = -ENOTDIR;
 644                 goto end_rmdir;
 645         }
 646         down(&inode->i_sem);
 647         if (!empty_dir (inode))
 648                 retval = -ENOTEMPTY;
 649         else if (de->inode != inode->i_ino)
 650                 retval = -ENOENT;
 651         else {
 652                 if (inode->i_count > 1) {
 653                 /*
 654                  * Are we deleting the last instance of a busy directory?
 655                  * Better clean up if so.
 656                  *
 657                  * Make directory empty (it will be truncated when finally
 658                  * dereferenced).  This also inhibits ext2_add_entry.
 659                  */
 660                         inode->i_size = 0;
 661                 }
 662                 retval = ext2_delete_entry (de, bh);
 663                 dir->i_version = ++event;
 664         }
 665         up(&inode->i_sem);
 666         if (retval)
 667                 goto end_rmdir;
 668         mark_buffer_dirty(bh, 1);
 669         if (IS_SYNC(dir)) {
 670                 ll_rw_block (WRITE, 1, &bh);
 671                 wait_on_buffer (bh);
 672         }
 673         if (inode->i_nlink != 2)
 674                 ext2_warning (inode->i_sb, "ext2_rmdir",
 675                               "empty directory has nlink!=2 (%d)",
 676                               inode->i_nlink);
 677         inode->i_version = ++event;
 678         inode->i_nlink = 0;
 679         inode->i_dirt = 1;
 680         dir->i_nlink--;
 681         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 682         dir->i_dirt = 1;
 683 end_rmdir:
 684         iput (dir);
 685         iput (inode);
 686         brelse (bh);
 687         return retval;
 688 }
 689 
 690 int ext2_unlink (struct inode * dir, const char * name, int len)
     /*  */
 691 {
 692         int retval;
 693         struct inode * inode;
 694         struct buffer_head * bh;
 695         struct ext2_dir_entry * de;
 696 
 697 repeat:
 698         if (!dir)
 699                 return -ENOENT;
 700         retval = -ENOENT;
 701         inode = NULL;
 702         bh = ext2_find_entry (dir, name, len, &de);
 703         if (!bh)
 704                 goto end_unlink;
 705         if (!(inode = iget (dir->i_sb, de->inode)))
 706                 goto end_unlink;
 707         if (inode->i_sb->dq_op)
 708                 inode->i_sb->dq_op->initialize (inode, -1);
 709         retval = -EPERM;
 710         if (S_ISDIR(inode->i_mode))
 711                 goto end_unlink;
 712         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 713                 goto end_unlink;
 714         if (de->inode != inode->i_ino) {
 715                 iput(inode);
 716                 brelse(bh);
 717                 current->counter = 0;
 718                 schedule();
 719                 goto repeat;
 720         }
 721         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 722             current->fsuid != inode->i_uid &&
 723             current->fsuid != dir->i_uid)
 724                 goto end_unlink;
 725         if (!inode->i_nlink) {
 726                 ext2_warning (inode->i_sb, "ext2_unlink",
 727                               "Deleting nonexistent file (%lu), %d",
 728                               inode->i_ino, inode->i_nlink);
 729                 inode->i_nlink = 1;
 730         }
 731         retval = ext2_delete_entry (de, bh);
 732         if (retval)
 733                 goto end_unlink;
 734         dir->i_version = ++event;
 735         mark_buffer_dirty(bh, 1);
 736         if (IS_SYNC(dir)) {
 737                 ll_rw_block (WRITE, 1, &bh);
 738                 wait_on_buffer (bh);
 739         }
 740         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 741         dir->i_dirt = 1;
 742         inode->i_nlink--;
 743         inode->i_dirt = 1;
 744         inode->i_ctime = dir->i_ctime;
 745         retval = 0;
 746 end_unlink:
 747         brelse (bh);
 748         iput (inode);
 749         iput (dir);
 750         return retval;
 751 }
 752 
 753 int ext2_symlink (struct inode * dir, const char * name, int len,
     /*  */
 754                   const char * symname)
 755 {
 756         struct ext2_dir_entry * de;
 757         struct inode * inode = NULL;
 758         struct buffer_head * bh = NULL, * name_block = NULL;
 759         char * link;
 760         int i, err;
 761         int l;
 762         char c;
 763 
 764         if (!(inode = ext2_new_inode (dir, S_IFLNK, &err))) {
 765                 iput (dir);
 766                 return err;
 767         }
 768         inode->i_mode = S_IFLNK | S_IRWXUGO;
 769         inode->i_op = &ext2_symlink_inode_operations;
 770         for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
 771              symname [l]; l++)
 772                 ;
 773         if (l >= sizeof (inode->u.ext2_i.i_data)) {
 774 
 775                 ext2_debug ("l=%d, normal symlink\n", l);
 776 
 777                 name_block = ext2_bread (inode, 0, 1, &err);
 778                 if (!name_block) {
 779                         iput (dir);
 780                         inode->i_nlink--;
 781                         inode->i_dirt = 1;
 782                         iput (inode);
 783                         return err;
 784                 }
 785                 link = name_block->b_data;
 786         } else {
 787                 link = (char *) inode->u.ext2_i.i_data;
 788 
 789                 ext2_debug ("l=%d, fast symlink\n", l);
 790 
 791         }
 792         i = 0;
 793         while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
 794                 link[i++] = c;
 795         link[i] = 0;
 796         if (name_block) {
 797                 mark_buffer_dirty(name_block, 1);
 798                 brelse (name_block);
 799         }
 800         inode->i_size = i;
 801         inode->i_dirt = 1;
 802 
 803         bh = ext2_find_entry (dir, name, len, &de);
 804         if (bh) {
 805                 inode->i_nlink--;
 806                 inode->i_dirt = 1;
 807                 iput (inode);
 808                 brelse (bh);
 809                 iput (dir);
 810                 return -EEXIST;
 811         }
 812         bh = ext2_add_entry (dir, name, len, &de, &err);
 813         if (!bh) {
 814                 inode->i_nlink--;
 815                 inode->i_dirt = 1;
 816                 iput (inode);
 817                 iput (dir);
 818                 return err;
 819         }
 820         de->inode = inode->i_ino;
 821         dir->i_version = ++event;
 822         dcache_add(dir, de->name, de->name_len, de->inode);
 823         mark_buffer_dirty(bh, 1);
 824         if (IS_SYNC(dir)) {
 825                 ll_rw_block (WRITE, 1, &bh);
 826                 wait_on_buffer (bh);
 827         }
 828         brelse (bh);
 829         iput (dir);
 830         iput (inode);
 831         return 0;
 832 }
 833 
 834 int ext2_link (struct inode * oldinode, struct inode * dir,
     /*  */
 835                const char * name, int len)
 836 {
 837         struct ext2_dir_entry * de;
 838         struct buffer_head * bh;
 839         int err;
 840 
 841         if (S_ISDIR(oldinode->i_mode)) {
 842                 iput (oldinode);
 843                 iput (dir);
 844                 return -EPERM;
 845         }
 846         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 847                 iput (oldinode);
 848                 iput (dir);
 849                 return -EPERM;
 850         }
 851         if (oldinode->i_nlink >= EXT2_LINK_MAX) {
 852                 iput (oldinode);
 853                 iput (dir);
 854                 return -EMLINK;
 855         }
 856         bh = ext2_find_entry (dir, name, len, &de);
 857         if (bh) {
 858                 brelse (bh);
 859                 iput (dir);
 860                 iput (oldinode);
 861                 return -EEXIST;
 862         }
 863         bh = ext2_add_entry (dir, name, len, &de, &err);
 864         if (!bh) {
 865                 iput (dir);
 866                 iput (oldinode);
 867                 return err;
 868         }
 869         de->inode = oldinode->i_ino;
 870         dir->i_version = ++event;
 871         dcache_add(dir, de->name, de->name_len, de->inode);
 872         mark_buffer_dirty(bh, 1);
 873         if (IS_SYNC(dir)) {
 874                 ll_rw_block (WRITE, 1, &bh);
 875                 wait_on_buffer (bh);
 876         }
 877         brelse (bh);
 878         iput (dir);
 879         oldinode->i_nlink++;
 880         oldinode->i_ctime = CURRENT_TIME;
 881         oldinode->i_dirt = 1;
 882         iput (oldinode);
 883         return 0;
 884 }
 885 
 886 static int subdir (struct inode * new_inode, struct inode * old_inode)
     /*  */
 887 {
 888         int ino;
 889         int result;
 890 
 891         new_inode->i_count++;
 892         result = 0;
 893         for (;;) {
 894                 if (new_inode == old_inode) {
 895                         result = 1;
 896                         break;
 897                 }
 898                 if (new_inode->i_dev != old_inode->i_dev)
 899                         break;
 900                 ino = new_inode->i_ino;
 901                 if (ext2_lookup (new_inode, "..", 2, &new_inode))
 902                         break;
 903                 if (new_inode->i_ino == ino)
 904                         break;
 905         }
 906         iput (new_inode);
 907         return result;
 908 }
 909 
 910 #define PARENT_INO(buffer) \
 911         ((struct ext2_dir_entry *) ((char *) buffer + \
 912         ((struct ext2_dir_entry *) buffer)->rec_len))->inode
 913 
 914 #define PARENT_NAME(buffer) \
 915         ((struct ext2_dir_entry *) ((char *) buffer + \
 916         ((struct ext2_dir_entry *) buffer)->rec_len))->name
 917 
 918 /*
 919  * rename uses retrying to avoid race-conditions: at least they should be
 920  * minimal.
 921  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 922  * checks fail, it tries to restart itself again. Very practical - no changes
 923  * are done until we know everything works ok.. and then all the changes can be
 924  * done in one fell swoop when we have claimed all the buffers needed.
 925  *
 926  * Anybody can rename anything with this: the permission checks are left to the
 927  * higher-level routines.
 928  */
 929 static int do_ext2_rename (struct inode * old_dir, const char * old_name,
     /*  */
 930                            int old_len, struct inode * new_dir,
 931                            const char * new_name, int new_len)
 932 {
 933         struct inode * old_inode, * new_inode;
 934         struct buffer_head * old_bh, * new_bh, * dir_bh;
 935         struct ext2_dir_entry * old_de, * new_de;
 936         int retval;
 937 
 938         goto start_up;
 939 try_again:
 940         if (new_bh && new_de) {
 941                 ext2_delete_entry(new_de, new_bh);
 942                 new_dir->i_version = ++event;
 943         }
 944         brelse (old_bh);
 945         brelse (new_bh);
 946         brelse (dir_bh);
 947         iput (old_inode);
 948         iput (new_inode);
 949         current->counter = 0;
 950         schedule ();
 951 start_up:
 952         old_inode = new_inode = NULL;
 953         old_bh = new_bh = dir_bh = NULL;
 954         new_de = NULL;
 955         old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
 956         retval = -ENOENT;
 957         if (!old_bh)
 958                 goto end_rename;
 959         old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
 960         if (!old_inode)
 961                 goto end_rename;
 962         retval = -EPERM;
 963         if ((old_dir->i_mode & S_ISVTX) && 
 964             current->fsuid != old_inode->i_uid &&
 965             current->fsuid != old_dir->i_uid && !fsuser())
 966                 goto end_rename;
 967         if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
 968                 goto end_rename;
 969         new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
 970         if (new_bh) {
 971                 new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
 972                 if (!new_inode) {
 973                         brelse (new_bh);
 974                         new_bh = NULL;
 975                 } else {
 976                         if (new_inode->i_sb->dq_op)
 977                                 new_inode->i_sb->dq_op->initialize (new_inode, -1);
 978                 }
 979         }
 980         if (new_inode == old_inode) {
 981                 retval = 0;
 982                 goto end_rename;
 983         }
 984         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 985                 retval = -EISDIR;
 986                 if (!S_ISDIR(old_inode->i_mode))
 987                         goto end_rename;
 988                 retval = -EINVAL;
 989                 if (subdir (new_dir, old_inode))
 990                         goto end_rename;
 991                 retval = -ENOTEMPTY;
 992                 if (!empty_dir (new_inode))
 993                         goto end_rename;
 994                 retval = -EBUSY;
 995                 if (new_inode->i_count > 1)
 996                         goto end_rename;
 997         }
 998         retval = -EPERM;
 999         if (new_inode && (new_dir->i_mode & S_ISVTX) &&
1000             current->fsuid != new_inode->i_uid &&
1001             current->fsuid != new_dir->i_uid && !fsuser())
1002                 goto end_rename;
1003         if (S_ISDIR(old_inode->i_mode)) {
1004                 retval = -ENOTDIR;
1005                 if (new_inode && !S_ISDIR(new_inode->i_mode))
1006                         goto end_rename;
1007                 retval = -EINVAL;
1008                 if (subdir (new_dir, old_inode))
1009                         goto end_rename;
1010                 dir_bh = ext2_bread (old_inode, 0, 0, &retval);
1011                 if (!dir_bh)
1012                         goto end_rename;
1013                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
1014                         goto end_rename;
1015                 retval = -EMLINK;
1016                 if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
1017                         goto end_rename;
1018         }
1019         if (!new_bh)
1020                 new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
1021                                          &retval);
1022         if (!new_bh)
1023                 goto end_rename;
1024         new_dir->i_version = ++event;
1025         /*
1026          * sanity checking before doing the rename - avoid races
1027          */
1028         if (new_inode && (new_de->inode != new_inode->i_ino))
1029                 goto try_again;
1030         if (new_de->inode && !new_inode)
1031                 goto try_again;
1032         if (old_de->inode != old_inode->i_ino)
1033                 goto try_again;
1034         /*
1035          * ok, that's it
1036          */
1037         new_de->inode = old_inode->i_ino;
1038         dcache_add(new_dir, new_de->name, new_de->name_len, new_de->inode);
1039         retval = ext2_delete_entry (old_de, old_bh);
1040         if (retval == -ENOENT)
1041                 goto try_again;
1042         if (retval)
1043                 goto end_rename;
1044         old_dir->i_version = ++event;
1045         if (new_inode) {
1046                 new_inode->i_nlink--;
1047                 new_inode->i_ctime = CURRENT_TIME;
1048                 new_inode->i_dirt = 1;
1049         }
1050         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
1051         old_dir->i_dirt = 1;
1052         if (dir_bh) {
1053                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
1054                 dcache_add(old_inode, "..", 2, new_dir->i_ino);
1055                 mark_buffer_dirty(dir_bh, 1);
1056                 old_dir->i_nlink--;
1057                 old_dir->i_dirt = 1;
1058                 if (new_inode) {
1059                         new_inode->i_nlink--;
1060                         new_inode->i_dirt = 1;
1061                 } else {
1062                         new_dir->i_nlink++;
1063                         new_dir->i_dirt = 1;
1064                 }
1065         }
1066         mark_buffer_dirty(old_bh,  1);
1067         if (IS_SYNC(old_dir)) {
1068                 ll_rw_block (WRITE, 1, &old_bh);
1069                 wait_on_buffer (old_bh);
1070         }
1071         mark_buffer_dirty(new_bh, 1);
1072         if (IS_SYNC(new_dir)) {
1073                 ll_rw_block (WRITE, 1, &new_bh);
1074                 wait_on_buffer (new_bh);
1075         }
1076         retval = 0;
1077 end_rename:
1078         brelse (dir_bh);
1079         brelse (old_bh);
1080         brelse (new_bh);
1081         iput (old_inode);
1082         iput (new_inode);
1083         iput (old_dir);
1084         iput (new_dir);
1085         return retval;
1086 }
1087 
1088 /*
1089  * Ok, rename also locks out other renames, as they can change the parent of
1090  * a directory, and we don't want any races. Other races are checked for by
1091  * "do_rename()", which restarts if there are inconsistencies.
1092  *
1093  * Note that there is no race between different filesystems: it's only within
1094  * the same device that races occur: many renames can happen at once, as long
1095  * as they are on different partitions.
1096  *
1097  * In the second extended file system, we use a lock flag stored in the memory
1098  * super-block.  This way, we really lock other renames only if they occur
1099  * on the same file system
1100  */
1101 int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
     /*  */
1102                  struct inode * new_dir, const char * new_name, int new_len)
1103 {
1104         int result;
1105 
1106         while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
1107                 sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1108         old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
1109         result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
1110                                  new_name, new_len);
1111         old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
1112         wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1113         return result;
1114 }
/* */
root/fs/ext2/namei.c

DEFINITIONS
