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 && !bh->b_uptodate)
 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 (!bh->b_uptodate) {
 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 && !bh->b_uptodate)
 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);
 379         if (!inode) {
 380                 iput (dir);
 381                 return -ENOSPC;
 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);
 425         if (!inode) {
 426                 iput (dir);
 427                 return -ENOSPC;
 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 = 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);
 492         if (!inode) {
 493                 iput (dir);
 494                 return -ENOSPC;
 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_dev != dir->i_dev)
 626                 goto end_rmdir;
 627         if (de->inode != inode->i_ino) {
 628                 iput(inode);
 629                 brelse(bh);
 630                 current->counter = 0;
 631                 schedule();
 632                 goto repeat;
 633         }
 634         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 635             current->fsuid != inode->i_uid &&
 636             current->fsuid != dir->i_uid)
 637                 goto end_rmdir;
 638         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 639                 goto end_rmdir;
 640         if (!S_ISDIR(inode->i_mode)) {
 641                 retval = -ENOTDIR;
 642                 goto end_rmdir;
 643         }
 644         down(&inode->i_sem);
 645         if (!empty_dir (inode))
 646                 retval = -ENOTEMPTY;
 647         else if (de->inode != inode->i_ino)
 648                 retval = -ENOENT;
 649         else {
 650                 if (inode->i_count > 1) {
 651                 /*
 652                  * Are we deleting the last instance of a busy directory?
 653                  * Better clean up if so.
 654                  *
 655                  * Make directory empty (it will be truncated when finally
 656                  * dereferenced).  This also inhibits ext2_add_entry.
 657                  */
 658                         inode->i_size = 0;
 659                 }
 660                 retval = ext2_delete_entry (de, bh);
 661                 dir->i_version = ++event;
 662         }
 663         up(&inode->i_sem);
 664         if (retval)
 665                 goto end_rmdir;
 666         mark_buffer_dirty(bh, 1);
 667         if (IS_SYNC(dir)) {
 668                 ll_rw_block (WRITE, 1, &bh);
 669                 wait_on_buffer (bh);
 670         }
 671         if (inode->i_nlink != 2)
 672                 ext2_warning (inode->i_sb, "ext2_rmdir",
 673                               "empty directory has nlink!=2 (%d)",
 674                               inode->i_nlink);
 675         inode->i_version = ++event;
 676         inode->i_nlink = 0;
 677         inode->i_dirt = 1;
 678         dir->i_nlink--;
 679         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 680         dir->i_dirt = 1;
 681 end_rmdir:
 682         iput (dir);
 683         iput (inode);
 684         brelse (bh);
 685         return retval;
 686 }
 687 
 688 int ext2_unlink (struct inode * dir, const char * name, int len)
     /*  */
 689 {
 690         int retval;
 691         struct inode * inode;
 692         struct buffer_head * bh;
 693         struct ext2_dir_entry * de;
 694 
 695 repeat:
 696         if (!dir)
 697                 return -ENOENT;
 698         retval = -ENOENT;
 699         inode = NULL;
 700         bh = ext2_find_entry (dir, name, len, &de);
 701         if (!bh)
 702                 goto end_unlink;
 703         if (!(inode = iget (dir->i_sb, de->inode)))
 704                 goto end_unlink;
 705         retval = -EPERM;
 706         if (S_ISDIR(inode->i_mode))
 707                 goto end_unlink;
 708         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 709                 goto end_unlink;
 710         if (de->inode != inode->i_ino) {
 711                 iput(inode);
 712                 brelse(bh);
 713                 current->counter = 0;
 714                 schedule();
 715                 goto repeat;
 716         }
 717         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 718             current->fsuid != inode->i_uid &&
 719             current->fsuid != dir->i_uid)
 720                 goto end_unlink;
 721         if (!inode->i_nlink) {
 722                 ext2_warning (inode->i_sb, "ext2_unlink",
 723                               "Deleting nonexistent file (%lu), %d",
 724                               inode->i_ino, inode->i_nlink);
 725                 inode->i_nlink = 1;
 726         }
 727         retval = ext2_delete_entry (de, bh);
 728         if (retval)
 729                 goto end_unlink;
 730         dir->i_version = ++event;
 731         mark_buffer_dirty(bh, 1);
 732         if (IS_SYNC(dir)) {
 733                 ll_rw_block (WRITE, 1, &bh);
 734                 wait_on_buffer (bh);
 735         }
 736         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 737         dir->i_dirt = 1;
 738         inode->i_nlink--;
 739         inode->i_dirt = 1;
 740         inode->i_ctime = dir->i_ctime;
 741         retval = 0;
 742 end_unlink:
 743         brelse (bh);
 744         iput (inode);
 745         iput (dir);
 746         return retval;
 747 }
 748 
 749 int ext2_symlink (struct inode * dir, const char * name, int len,
     /*  */
 750                   const char * symname)
 751 {
 752         struct ext2_dir_entry * de;
 753         struct inode * inode = NULL;
 754         struct buffer_head * bh = NULL, * name_block = NULL;
 755         char * link;
 756         int i, err;
 757         int l;
 758         char c;
 759 
 760         if (!(inode = ext2_new_inode (dir, S_IFLNK))) {
 761                 iput (dir);
 762                 return -ENOSPC;
 763         }
 764         inode->i_mode = S_IFLNK | S_IRWXUGO;
 765         inode->i_op = &ext2_symlink_inode_operations;
 766         for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
 767              symname [l]; l++)
 768                 ;
 769         if (l >= sizeof (inode->u.ext2_i.i_data)) {
 770 
 771                 ext2_debug ("l=%d, normal symlink\n", l);
 772 
 773                 name_block = ext2_bread (inode, 0, 1, &err);
 774                 if (!name_block) {
 775                         iput (dir);
 776                         inode->i_nlink--;
 777                         inode->i_dirt = 1;
 778                         iput (inode);
 779                         return err;
 780                 }
 781                 link = name_block->b_data;
 782         } else {
 783                 link = (char *) inode->u.ext2_i.i_data;
 784 
 785                 ext2_debug ("l=%d, fast symlink\n", l);
 786 
 787         }
 788         i = 0;
 789         while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
 790                 link[i++] = c;
 791         link[i] = 0;
 792         if (name_block) {
 793                 mark_buffer_dirty(name_block, 1);
 794                 brelse (name_block);
 795         }
 796         inode->i_size = i;
 797         inode->i_dirt = 1;
 798         bh = ext2_find_entry (dir, name, len, &de);
 799         if (bh) {
 800                 inode->i_nlink--;
 801                 inode->i_dirt = 1;
 802                 iput (inode);
 803                 brelse (bh);
 804                 iput (dir);
 805                 return -EEXIST;
 806         }
 807         bh = ext2_add_entry (dir, name, len, &de, &err);
 808         if (!bh) {
 809                 inode->i_nlink--;
 810                 inode->i_dirt = 1;
 811                 iput (inode);
 812                 iput (dir);
 813                 return err;
 814         }
 815         de->inode = inode->i_ino;
 816         dir->i_version = ++event;
 817         dcache_add(dir, de->name, de->name_len, de->inode);
 818         mark_buffer_dirty(bh, 1);
 819         if (IS_SYNC(dir)) {
 820                 ll_rw_block (WRITE, 1, &bh);
 821                 wait_on_buffer (bh);
 822         }
 823         brelse (bh);
 824         iput (dir);
 825         iput (inode);
 826         return 0;
 827 }
 828 
 829 int ext2_link (struct inode * oldinode, struct inode * dir,
     /*  */
 830                const char * name, int len)
 831 {
 832         struct ext2_dir_entry * de;
 833         struct buffer_head * bh;
 834         int err;
 835 
 836         if (S_ISDIR(oldinode->i_mode)) {
 837                 iput (oldinode);
 838                 iput (dir);
 839                 return -EPERM;
 840         }
 841         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 842                 iput (oldinode);
 843                 iput (dir);
 844                 return -EPERM;
 845         }
 846         if (oldinode->i_nlink >= EXT2_LINK_MAX) {
 847                 iput (oldinode);
 848                 iput (dir);
 849                 return -EMLINK;
 850         }
 851         bh = ext2_find_entry (dir, name, len, &de);
 852         if (bh) {
 853                 brelse (bh);
 854                 iput (dir);
 855                 iput (oldinode);
 856                 return -EEXIST;
 857         }
 858         bh = ext2_add_entry (dir, name, len, &de, &err);
 859         if (!bh) {
 860                 iput (dir);
 861                 iput (oldinode);
 862                 return err;
 863         }
 864         de->inode = oldinode->i_ino;
 865         dir->i_version = ++event;
 866         dcache_add(dir, de->name, de->name_len, de->inode);
 867         mark_buffer_dirty(bh, 1);
 868         if (IS_SYNC(dir)) {
 869                 ll_rw_block (WRITE, 1, &bh);
 870                 wait_on_buffer (bh);
 871         }
 872         brelse (bh);
 873         iput (dir);
 874         oldinode->i_nlink++;
 875         oldinode->i_ctime = CURRENT_TIME;
 876         oldinode->i_dirt = 1;
 877         iput (oldinode);
 878         return 0;
 879 }
 880 
 881 static int subdir (struct inode * new_inode, struct inode * old_inode)
     /*  */
 882 {
 883         int ino;
 884         int result;
 885 
 886         new_inode->i_count++;
 887         result = 0;
 888         for (;;) {
 889                 if (new_inode == old_inode) {
 890                         result = 1;
 891                         break;
 892                 }
 893                 if (new_inode->i_dev != old_inode->i_dev)
 894                         break;
 895                 ino = new_inode->i_ino;
 896                 if (ext2_lookup (new_inode, "..", 2, &new_inode))
 897                         break;
 898                 if (new_inode->i_ino == ino)
 899                         break;
 900         }
 901         iput (new_inode);
 902         return result;
 903 }
 904 
 905 #define PARENT_INO(buffer) \
 906         ((struct ext2_dir_entry *) ((char *) buffer + \
 907         ((struct ext2_dir_entry *) buffer)->rec_len))->inode
 908 
 909 #define PARENT_NAME(buffer) \
 910         ((struct ext2_dir_entry *) ((char *) buffer + \
 911         ((struct ext2_dir_entry *) buffer)->rec_len))->name
 912 
 913 /*
 914  * rename uses retrying to avoid race-conditions: at least they should be
 915  * minimal.
 916  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 917  * checks fail, it tries to restart itself again. Very practical - no changes
 918  * are done until we know everything works ok.. and then all the changes can be
 919  * done in one fell swoop when we have claimed all the buffers needed.
 920  *
 921  * Anybody can rename anything with this: the permission checks are left to the
 922  * higher-level routines.
 923  */
 924 static int do_ext2_rename (struct inode * old_dir, const char * old_name,
     /*  */
 925                            int old_len, struct inode * new_dir,
 926                            const char * new_name, int new_len)
 927 {
 928         struct inode * old_inode, * new_inode;
 929         struct buffer_head * old_bh, * new_bh, * dir_bh;
 930         struct ext2_dir_entry * old_de, * new_de;
 931         int retval;
 932 
 933         goto start_up;
 934 try_again:
 935         if (new_bh && new_de) {
 936                 ext2_delete_entry(new_de, new_bh);
 937                 new_dir->i_version = ++event;
 938         }
 939         brelse (old_bh);
 940         brelse (new_bh);
 941         brelse (dir_bh);
 942         iput (old_inode);
 943         iput (new_inode);
 944         current->counter = 0;
 945         schedule ();
 946 start_up:
 947         old_inode = new_inode = NULL;
 948         old_bh = new_bh = dir_bh = NULL;
 949         new_de = NULL;
 950         old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
 951         retval = -ENOENT;
 952         if (!old_bh)
 953                 goto end_rename;
 954         old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
 955         if (!old_inode)
 956                 goto end_rename;
 957         retval = -EPERM;
 958         if ((old_dir->i_mode & S_ISVTX) && 
 959             current->fsuid != old_inode->i_uid &&
 960             current->fsuid != old_dir->i_uid && !fsuser())
 961                 goto end_rename;
 962         if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
 963                 goto end_rename;
 964         new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
 965         if (new_bh) {
 966                 new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
 967                 if (!new_inode) {
 968                         brelse (new_bh);
 969                         new_bh = NULL;
 970                 }
 971         }
 972         if (new_inode == old_inode) {
 973                 retval = 0;
 974                 goto end_rename;
 975         }
 976         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 977                 retval = -EISDIR;
 978                 if (!S_ISDIR(old_inode->i_mode))
 979                         goto end_rename;
 980                 retval = -EINVAL;
 981                 if (subdir (new_dir, old_inode))
 982                         goto end_rename;
 983                 retval = -ENOTEMPTY;
 984                 if (!empty_dir (new_inode))
 985                         goto end_rename;
 986                 retval = -EBUSY;
 987                 if (new_inode->i_count > 1)
 988                         goto end_rename;
 989         }
 990         retval = -EPERM;
 991         if (new_inode && (new_dir->i_mode & S_ISVTX) &&
 992             current->fsuid != new_inode->i_uid &&
 993             current->fsuid != new_dir->i_uid && !fsuser())
 994                 goto end_rename;
 995         if (S_ISDIR(old_inode->i_mode)) {
 996                 retval = -ENOTDIR;
 997                 if (new_inode && !S_ISDIR(new_inode->i_mode))
 998                         goto end_rename;
 999                 retval = -EINVAL;
1000                 if (subdir (new_dir, old_inode))
1001                         goto end_rename;
1002                 dir_bh = ext2_bread (old_inode, 0, 0, &retval);
1003                 if (!dir_bh)
1004                         goto end_rename;
1005                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
1006                         goto end_rename;
1007                 retval = -EMLINK;
1008                 if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
1009                         goto end_rename;
1010         }
1011         if (!new_bh)
1012                 new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
1013                                          &retval);
1014         if (!new_bh)
1015                 goto end_rename;
1016         new_dir->i_version = ++event;
1017         /*
1018          * sanity checking before doing the rename - avoid races
1019          */
1020         if (new_inode && (new_de->inode != new_inode->i_ino))
1021                 goto try_again;
1022         if (new_de->inode && !new_inode)
1023                 goto try_again;
1024         if (old_de->inode != old_inode->i_ino)
1025                 goto try_again;
1026         /*
1027          * ok, that's it
1028          */
1029         new_de->inode = old_inode->i_ino;
1030         dcache_add(new_dir, new_de->name, new_de->name_len, new_de->inode);
1031         retval = ext2_delete_entry (old_de, old_bh);
1032         if (retval == -ENOENT)
1033                 goto try_again;
1034         if (retval)
1035                 goto end_rename;
1036         old_dir->i_version = ++event;
1037         if (new_inode) {
1038                 new_inode->i_nlink--;
1039                 new_inode->i_ctime = CURRENT_TIME;
1040                 new_inode->i_dirt = 1;
1041         }
1042         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
1043         old_dir->i_dirt = 1;
1044         if (dir_bh) {
1045                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
1046                 dcache_add(old_inode, "..", 2, new_dir->i_ino);
1047                 mark_buffer_dirty(dir_bh, 1);
1048                 old_dir->i_nlink--;
1049                 old_dir->i_dirt = 1;
1050                 if (new_inode) {
1051                         new_inode->i_nlink--;
1052                         new_inode->i_dirt = 1;
1053                 } else {
1054                         new_dir->i_nlink++;
1055                         new_dir->i_dirt = 1;
1056                 }
1057         }
1058         mark_buffer_dirty(old_bh,  1);
1059         if (IS_SYNC(old_dir)) {
1060                 ll_rw_block (WRITE, 1, &old_bh);
1061                 wait_on_buffer (old_bh);
1062         }
1063         mark_buffer_dirty(new_bh, 1);
1064         if (IS_SYNC(new_dir)) {
1065                 ll_rw_block (WRITE, 1, &new_bh);
1066                 wait_on_buffer (new_bh);
1067         }
1068         retval = 0;
1069 end_rename:
1070         brelse (dir_bh);
1071         brelse (old_bh);
1072         brelse (new_bh);
1073         iput (old_inode);
1074         iput (new_inode);
1075         iput (old_dir);
1076         iput (new_dir);
1077         return retval;
1078 }
1079 
1080 /*
1081  * Ok, rename also locks out other renames, as they can change the parent of
1082  * a directory, and we don't want any races. Other races are checked for by
1083  * "do_rename()", which restarts if there are inconsistencies.
1084  *
1085  * Note that there is no race between different filesystems: it's only within
1086  * the same device that races occur: many renames can happen at once, as long
1087  * as they are on different partitions.
1088  *
1089  * In the second extended file system, we use a lock flag stored in the memory
1090  * super-block.  This way, we really lock other renames only if they occur
1091  * on the same file system
1092  */
1093 int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
     /*  */
1094                  struct inode * new_dir, const char * new_name, int new_len)
1095 {
1096         int result;
1097 
1098         while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
1099                 sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1100         old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
1101         result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
1102                                  new_name, new_len);
1103         old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
1104         wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1105         return result;
1106 }
/* */
root/fs/ext2/namei.c

DEFINITIONS
