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  Remy Card (card@masi.ibp.fr)
   5  *                                  Laboratoire MASI - Institut Blaise Pascal
   6  *                                  Universite Pierre et Marie Curie (Paris VI)
   7  *
   8  *  from
   9  *
  10  *  linux/fs/minix/namei.c
  11  *
  12  *  Copyright (C) 1991, 1992  Linus Torvalds
  13  */
  14 
  15 #include <asm/segment.h>
  16 
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/ext2_fs.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/sched.h>
  22 #include <linux/stat.h>
  23 #include <linux/string.h>
  24 #include <linux/locks.h>
  25 
  26 /*
  27  * comment out this line if you want names > EXT2_NAME_LEN chars to be
  28  * truncated. Else they will be disallowed.
  29  */
  30 /* #define NO_TRUNCATE */
  31 
  32 /*
  33  * define how far ahead to read directories while searching them.
  34  */
  35 #define NAMEI_RA_CHUNKS  2
  36 #define NAMEI_RA_BLOCKS  4
  37 #define NAMEI_RA_SIZE        (NAMEI_RA_CHUNKS * NAMEI_RA_BLOCKS)
  38 #define NAMEI_RA_INDEX(c,b)  (((c) * NAMEI_RA_BLOCKS) + (b))
  39 
  40 /*
  41  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
  42  */
  43 static int ext2_match (int len, const char * const name,
     /*  */
  44                        struct ext2_dir_entry * de)
  45 {
  46         if (!de || !de->inode || len > EXT2_NAME_LEN)
  47                 return 0;
  48         /*
  49          * "" means "." ---> so paths like "/usr/lib//libc.a" work
  50          */
  51         if (!len && de->name_len == 1 && (de->name[0] == '.') &&
  52            (de->name[1] == '\0'))
  53                 return 1;
  54         if (len != de->name_len)
  55                 return 0;
  56         return !memcmp(name, de->name, len);
  57 }
  58 
  59 /*
  60  *      ext2_find_entry()
  61  *
  62  * finds an entry in the specified directory with the wanted name. It
  63  * returns the cache buffer in which the entry was found, and the entry
  64  * itself (as a parameter - res_dir). It does NOT read the inode of the
  65  * entry - you'll have to do that yourself if you want to.
  66  */
  67 static struct buffer_head * ext2_find_entry (struct inode * dir,
     /*  */
  68                                              const char * const name, int namelen,
  69                                              struct ext2_dir_entry ** res_dir)
  70 {
  71         struct super_block * sb;
  72         struct buffer_head * bh_use[NAMEI_RA_SIZE];
  73         struct buffer_head * bh_read[NAMEI_RA_SIZE];
  74         unsigned long offset;
  75         int block, toread, i, err;
  76 
  77         *res_dir = NULL;
  78         if (!dir)
  79                 return NULL;
  80         sb = dir->i_sb;
  81 
  82 #ifdef NO_TRUNCATE
  83         if (namelen > EXT2_NAME_LEN)
  84                 return NULL;
  85 #else
  86         if (namelen > EXT2_NAME_LEN)
  87                 namelen = EXT2_NAME_LEN;
  88 #endif
  89 
  90         memset (bh_use, 0, sizeof (bh_use));
  91         toread = 0;
  92         for (block = 0; block < NAMEI_RA_SIZE; ++block) {
  93                 struct buffer_head * bh;
  94 
  95                 if ((block << EXT2_BLOCK_SIZE_BITS (sb)) >= dir->i_size)
  96                         break;
  97                 bh = ext2_getblk (dir, block, 0, &err);
  98                 bh_use[block] = bh;
  99                 if (bh && !bh->b_uptodate)
 100                         bh_read[toread++] = bh;
 101         }
 102 
 103         block = 0;
 104         offset = 0;
 105         while (offset < dir->i_size) {
 106                 struct buffer_head * bh;
 107                 struct ext2_dir_entry * de;
 108                 char * dlimit;
 109 
 110                 if ((block % NAMEI_RA_BLOCKS) == 0 && toread) {
 111                         ll_rw_block (READ, toread, bh_read);
 112                         toread = 0;
 113                 }
 114                 bh = bh_use[block % NAMEI_RA_SIZE];
 115                 if (!bh)
 116                         ext2_panic (sb, "ext2_find_entry",
 117                                     "buffer head pointer is NULL");
 118                 wait_on_buffer (bh);
 119                 if (!bh->b_uptodate) {
 120                         /*
 121                          * read error: all bets are off
 122                          */
 123                         break;
 124                 }
 125 
 126                 de = (struct ext2_dir_entry *) bh->b_data;
 127                 dlimit = bh->b_data + sb->s_blocksize;
 128                 while ((char *) de < dlimit) {
 129                         if (!ext2_check_dir_entry ("ext2_find_entry", dir,
 130                                                    de, bh, offset))
 131                                 goto failure;
 132                         if (de->inode != 0 && ext2_match (namelen, name, de)) {
 133                                 for (i = 0; i < NAMEI_RA_SIZE; ++i) {
 134                                         if (bh_use[i] != bh)
 135                                                 brelse (bh_use[i]);
 136                                 }
 137                                 *res_dir = de;
 138                                 return bh;
 139                         }
 140                         offset += de->rec_len;
 141                         de = (struct ext2_dir_entry *)
 142                                 ((char *) de + de->rec_len);
 143                 }
 144 
 145                 brelse (bh);
 146                 if (((block + NAMEI_RA_SIZE) << EXT2_BLOCK_SIZE_BITS (sb)) >=
 147                     dir->i_size)
 148                         bh = NULL;
 149                 else
 150                         bh = ext2_getblk (dir, block + NAMEI_RA_SIZE, 0, &err);
 151                 bh_use[block++ % NAMEI_RA_SIZE] = bh;
 152                 if (bh && !bh->b_uptodate)
 153                         bh_read[toread++] = bh;
 154         }
 155 
 156 failure:
 157         for (i = 0; i < NAMEI_RA_SIZE; ++i)
 158                 brelse (bh_use[i]);
 159         return NULL;
 160 }
 161 
 162 int ext2_lookup (struct inode * dir, const char * name, int len,
     /*  */
 163                  struct inode ** result)
 164 {
 165         unsigned long ino;
 166         struct ext2_dir_entry * de;
 167         struct buffer_head * bh;
 168 
 169         *result = NULL;
 170         if (!dir)
 171                 return -ENOENT;
 172         if (!S_ISDIR(dir->i_mode)) {
 173                 iput (dir);
 174                 return -ENOENT;
 175         }
 176         if (dcache_lookup(dir, name, len, &ino)) {
 177                 if (!ino) {
 178                         iput(dir);
 179                         return -ENOENT;
 180                 }
 181                 if (!(*result = iget (dir->i_sb, ino))) {
 182                         iput (dir);
 183                         return -EACCES;
 184                 }
 185                 iput (dir);
 186                 return 0;
 187         }
 188         ino = dir->i_version;
 189         if (!(bh = ext2_find_entry (dir, name, len, &de))) {
 190                 if (ino == dir->i_version)
 191                         dcache_add(dir, name, len, 0);
 192                 iput (dir);
 193                 return -ENOENT;
 194         }
 195         ino = de->inode;
 196         dcache_add(dir, name, len, ino);
 197         brelse (bh);
 198         if (!(*result = iget (dir->i_sb, ino))) {
 199                 iput (dir);
 200                 return -EACCES;
 201         }
 202         iput (dir);
 203         return 0;
 204 }
 205 
 206 /*
 207  *      ext2_add_entry()
 208  *
 209  * adds a file entry to the specified directory, using the same
 210  * semantics as ext2_find_entry(). It returns NULL if it failed.
 211  *
 212  * NOTE!! The inode part of 'de' is left at 0 - which means you
 213  * may not sleep between calling this and putting something into
 214  * the entry, as someone else might have used it while you slept.
 215  */
 216 static struct buffer_head * ext2_add_entry (struct inode * dir,
     /*  */
 217                                             const char * name, int namelen,
 218                                             struct ext2_dir_entry ** res_dir,
 219                                             int *err)
 220 {
 221         unsigned long offset;
 222         unsigned short rec_len;
 223         struct buffer_head * bh;
 224         struct ext2_dir_entry * de, * de1;
 225         struct super_block * sb;
 226 
 227         *err = -EINVAL;
 228         *res_dir = NULL;
 229         if (!dir)
 230                 return NULL;
 231         sb = dir->i_sb;
 232 #ifdef NO_TRUNCATE
 233         if (namelen > EXT2_NAME_LEN)
 234                 return NULL;
 235 #else
 236         if (namelen > EXT2_NAME_LEN)
 237                 namelen = EXT2_NAME_LEN;
 238 #endif
 239         if (!namelen)
 240                 return NULL;
 241         /*
 242          * Is this a busy deleted directory?  Can't create new files if so
 243          */
 244         if (dir->i_size == 0)
 245         {
 246                 *err = -ENOENT;
 247                 return NULL;
 248         }
 249         bh = ext2_bread (dir, 0, 0, err);
 250         if (!bh)
 251                 return NULL;
 252         rec_len = EXT2_DIR_REC_LEN(namelen);
 253         offset = 0;
 254         de = (struct ext2_dir_entry *) bh->b_data;
 255         *err = -ENOSPC;
 256         while (1) {
 257                 if ((char *)de >= sb->s_blocksize + bh->b_data) {
 258                         brelse (bh);
 259                         bh = NULL;
 260                         bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, err);
 261                         if (!bh)
 262                                 return NULL;
 263                         if (dir->i_size <= offset) {
 264                                 if (dir->i_size == 0) {
 265                                         *err = -ENOENT;
 266                                         return NULL;
 267                                 }
 268 
 269                                 ext2_debug ("creating next block\n");
 270 
 271                                 de = (struct ext2_dir_entry *) bh->b_data;
 272                                 de->inode = 0;
 273                                 de->rec_len = sb->s_blocksize;
 274                                 dir->i_size = offset + sb->s_blocksize;
 275                                 dir->i_dirt = 1;
 276                         } else {
 277 
 278                                 ext2_debug ("skipping to next block\n");
 279 
 280                                 de = (struct ext2_dir_entry *) bh->b_data;
 281                         }
 282                 }
 283                 if (!ext2_check_dir_entry ("ext2_add_entry", dir, de, bh,
 284                                            offset)) {
 285                         *err = -ENOENT;
 286                         brelse (bh);
 287                         return NULL;
 288                 }
 289                 if (de->inode != 0 && ext2_match (namelen, name, de)) {
 290                                 *err = -EEXIST;
 291                                 brelse (bh);
 292                                 return NULL;
 293                 }
 294                 if ((de->inode == 0 && de->rec_len >= rec_len) ||
 295                     (de->rec_len >= EXT2_DIR_REC_LEN(de->name_len) + rec_len)) {
 296                         offset += de->rec_len;
 297                         if (de->inode) {
 298                                 de1 = (struct ext2_dir_entry *) ((char *) de +
 299                                         EXT2_DIR_REC_LEN(de->name_len));
 300                                 de1->rec_len = de->rec_len -
 301                                         EXT2_DIR_REC_LEN(de->name_len);
 302                                 de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 303                                 de = de1;
 304                         }
 305                         de->inode = 0;
 306                         de->name_len = namelen;
 307                         memcpy (de->name, name, namelen);
 308                         /*
 309                          * XXX shouldn't update any times until successful
 310                          * completion of syscall, but too many callers depend
 311                          * on this.
 312                          *
 313                          * XXX similarly, too many callers depend on
 314                          * ext2_new_inode() setting the times, but error
 315                          * recovery deletes the inode, so the worst that can
 316                          * happen is that the times are slightly out of date
 317                          * and/or different from the directory change time.
 318                          */
 319                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 320                         dir->i_dirt = 1;
 321                         mark_buffer_dirty(bh, 1);
 322                         *res_dir = de;
 323                         *err = 0;
 324                         return bh;
 325                 }
 326                 offset += de->rec_len;
 327                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 328         }
 329         brelse (bh);
 330         return NULL;
 331 }
 332 
 333 /*
 334  * ext2_delete_entry deletes a directory entry by merging it with the
 335  * previous entry
 336  */
 337 static int ext2_delete_entry (struct ext2_dir_entry * dir,
     /*  */
 338                               struct buffer_head * bh)
 339 {
 340         struct ext2_dir_entry * de, * pde;
 341         int i;
 342 
 343         i = 0;
 344         pde = NULL;
 345         de = (struct ext2_dir_entry *) bh->b_data;
 346         while (i < bh->b_size) {
 347                 if (!ext2_check_dir_entry ("ext2_delete_entry", NULL, 
 348                                            de, bh, i))
 349                         return -EIO;
 350                 if (de == dir)  {
 351                         if (pde)
 352                                 pde->rec_len += dir->rec_len;
 353                         dir->inode = 0;
 354                         return 0;
 355                 }
 356                 i += de->rec_len;
 357                 pde = de;
 358                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 359         }
 360         return -ENOENT;
 361 }
 362 
 363 int ext2_create (struct inode * dir,const char * name, int len, int mode,
     /*  */
 364                  struct inode ** result)
 365 {
 366         struct inode * inode;
 367         struct buffer_head * bh;
 368         struct ext2_dir_entry * de;
 369         int err;
 370 
 371         *result = NULL;
 372         if (!dir)
 373                 return -ENOENT;
 374         inode = ext2_new_inode (dir, mode);
 375         if (!inode) {
 376                 iput (dir);
 377                 return -ENOSPC;
 378         }
 379         inode->i_op = &ext2_file_inode_operations;
 380         inode->i_mode = mode;
 381         inode->i_dirt = 1;
 382         bh = ext2_add_entry (dir, name, len, &de, &err);
 383         if (!bh) {
 384                 inode->i_nlink--;
 385                 inode->i_dirt = 1;
 386                 iput (inode);
 387                 iput (dir);
 388                 return err;
 389         }
 390         de->inode = inode->i_ino;
 391         dir->i_version = ++event;
 392         dcache_add(dir, de->name, de->name_len, de->inode);
 393         mark_buffer_dirty(bh, 1);
 394         if (IS_SYNC(dir)) {
 395                 ll_rw_block (WRITE, 1, &bh);
 396                 wait_on_buffer (bh);
 397         }
 398         brelse (bh);
 399         iput (dir);
 400         *result = inode;
 401         return 0;
 402 }
 403 
 404 int ext2_mknod (struct inode * dir, const char * name, int len, int mode,
     /*  */
 405                 int rdev)
 406 {
 407         struct inode * inode;
 408         struct buffer_head * bh;
 409         struct ext2_dir_entry * de;
 410         int err;
 411 
 412         if (!dir)
 413                 return -ENOENT;
 414         bh = ext2_find_entry (dir, name, len, &de);
 415         if (bh) {
 416                 brelse (bh);
 417                 iput (dir);
 418                 return -EEXIST;
 419         }
 420         inode = ext2_new_inode (dir, mode);
 421         if (!inode) {
 422                 iput (dir);
 423                 return -ENOSPC;
 424         }
 425         inode->i_uid = current->fsuid;
 426         inode->i_mode = mode;
 427         inode->i_op = NULL;
 428         if (S_ISREG(inode->i_mode))
 429                 inode->i_op = &ext2_file_inode_operations;
 430         else if (S_ISDIR(inode->i_mode)) {
 431                 inode->i_op = &ext2_dir_inode_operations;
 432                 if (dir->i_mode & S_ISGID)
 433                         inode->i_mode |= S_ISGID;
 434         }
 435         else if (S_ISLNK(inode->i_mode))
 436                 inode->i_op = &ext2_symlink_inode_operations;
 437         else if (S_ISCHR(inode->i_mode))
 438                 inode->i_op = &chrdev_inode_operations;
 439         else if (S_ISBLK(inode->i_mode))
 440                 inode->i_op = &blkdev_inode_operations;
 441         else if (S_ISFIFO(inode->i_mode)) 
 442                 init_fifo(inode);
 443         if (S_ISBLK(mode) || S_ISCHR(mode))
 444                 inode->i_rdev = rdev;
 445         inode->i_dirt = 1;
 446         bh = ext2_add_entry (dir, name, len, &de, &err);
 447         if (!bh) {
 448                 inode->i_nlink--;
 449                 inode->i_dirt = 1;
 450                 iput (inode);
 451                 iput (dir);
 452                 return err;
 453         }
 454         de->inode = inode->i_ino;
 455         dir->i_version = ++event;
 456         dcache_add(dir, de->name, de->name_len, de->inode);
 457         mark_buffer_dirty(bh, 1);
 458         if (IS_SYNC(dir)) {
 459                 ll_rw_block (WRITE, 1, &bh);
 460                 wait_on_buffer (bh);
 461         }
 462         brelse (bh);
 463         iput (dir);
 464         iput (inode);
 465         return 0;
 466 }
 467 
 468 int ext2_mkdir (struct inode * dir, const char * name, int len, int mode)
     /*  */
 469 {
 470         struct inode * inode;
 471         struct buffer_head * bh, * dir_block;
 472         struct ext2_dir_entry * de;
 473         int err;
 474 
 475         if (!dir)
 476                 return -ENOENT;
 477         bh = ext2_find_entry (dir, name, len, &de);
 478         if (bh) {
 479                 brelse (bh);
 480                 iput (dir);
 481                 return -EEXIST;
 482         }
 483         if (dir->i_nlink >= EXT2_LINK_MAX) {
 484                 iput (dir);
 485                 return -EMLINK;
 486         }
 487         inode = ext2_new_inode (dir, S_IFDIR);
 488         if (!inode) {
 489                 iput (dir);
 490                 return -ENOSPC;
 491         }
 492         inode->i_op = &ext2_dir_inode_operations;
 493         inode->i_size = inode->i_sb->s_blocksize;
 494         dir_block = ext2_bread (inode, 0, 1, &err);
 495         if (!dir_block) {
 496                 iput (dir);
 497                 inode->i_nlink--;
 498                 inode->i_dirt = 1;
 499                 iput (inode);
 500                 return err;
 501         }
 502         inode->i_blocks = inode->i_sb->s_blocksize / 512;
 503         de = (struct ext2_dir_entry *) dir_block->b_data;
 504         de->inode = inode->i_ino;
 505         de->name_len = 1;
 506         de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 507         strcpy (de->name, ".");
 508         de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 509         de->inode = dir->i_ino;
 510         de->rec_len = inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1);
 511         de->name_len = 2;
 512         strcpy (de->name, "..");
 513         inode->i_nlink = 2;
 514         mark_buffer_dirty(dir_block, 1);
 515         brelse (dir_block);
 516         inode->i_mode = S_IFDIR | (mode & S_IRWXUGO & ~current->fs->umask);
 517         if (dir->i_mode & S_ISGID)
 518                 inode->i_mode |= S_ISGID;
 519         inode->i_dirt = 1;
 520         bh = ext2_add_entry (dir, name, len, &de, &err);
 521         if (!bh) {
 522                 iput (dir);
 523                 inode->i_nlink = 0;
 524                 inode->i_dirt = 1;
 525                 iput (inode);
 526                 return err;
 527         }
 528         de->inode = inode->i_ino;
 529         dir->i_version = ++event;
 530         dcache_add(dir, de->name, de->name_len, de->inode);
 531         mark_buffer_dirty(bh, 1);
 532         if (IS_SYNC(dir)) {
 533                 ll_rw_block (WRITE, 1, &bh);
 534                 wait_on_buffer (bh);
 535         }
 536         dir->i_nlink++;
 537         dir->i_dirt = 1;
 538         iput (dir);
 539         iput (inode);
 540         brelse (bh);
 541         return 0;
 542 }
 543 
 544 /*
 545  * routine to check that the specified directory is empty (for rmdir)
 546  */
 547 static int empty_dir (struct inode * inode)
     /*  */
 548 {
 549         unsigned long offset;
 550         struct buffer_head * bh;
 551         struct ext2_dir_entry * de, * de1;
 552         struct super_block * sb;
 553         int err;
 554 
 555         sb = inode->i_sb;
 556         if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
 557             !(bh = ext2_bread (inode, 0, 0, &err))) {
 558                 ext2_warning (inode->i_sb, "empty_dir",
 559                               "bad directory (dir %lu)", inode->i_ino);
 560                 return 1;
 561         }
 562         de = (struct ext2_dir_entry *) bh->b_data;
 563         de1 = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 564         if (de->inode != inode->i_ino || !de1->inode || 
 565             strcmp (".", de->name) || strcmp ("..", de1->name)) {
 566                 ext2_warning (inode->i_sb, "empty_dir",
 567                               "bad directory (dir %lu)", inode->i_ino);
 568                 return 1;
 569         }
 570         offset = de->rec_len + de1->rec_len;
 571         de = (struct ext2_dir_entry *) ((char *) de1 + de1->rec_len);
 572         while (offset < inode->i_size ) {
 573                 if ((void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
 574                         brelse (bh);
 575                         bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
 576                         if (!bh) {
 577                                 offset += sb->s_blocksize;
 578                                 continue;
 579                         }
 580                         de = (struct ext2_dir_entry *) bh->b_data;
 581                 }
 582                 if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
 583                                            offset)) {
 584                         brelse (bh);
 585                         return 1;
 586                 }
 587                 if (de->inode) {
 588                         brelse (bh);
 589                         return 0;
 590                 }
 591                 offset += de->rec_len;
 592                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 593         }
 594         brelse (bh);
 595         return 1;
 596 }
 597 
 598 int ext2_rmdir (struct inode * dir, const char * name, int len)
     /*  */
 599 {
 600         int retval;
 601         struct inode * inode;
 602         struct buffer_head * bh;
 603         struct ext2_dir_entry * de;
 604 
 605 repeat:
 606         if (!dir)
 607                 return -ENOENT;
 608         inode = NULL;
 609         bh = ext2_find_entry (dir, name, len, &de);
 610         retval = -ENOENT;
 611         if (!bh)
 612                 goto end_rmdir;
 613         retval = -EPERM;
 614         if (!(inode = iget (dir->i_sb, de->inode)))
 615                 goto end_rmdir;
 616         if (inode->i_dev != dir->i_dev)
 617                 goto end_rmdir;
 618         if (de->inode != inode->i_ino) {
 619                 iput(inode);
 620                 brelse(bh);
 621                 current->counter = 0;
 622                 schedule();
 623                 goto repeat;
 624         }
 625         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 626             current->fsuid != inode->i_uid &&
 627             current->fsuid != dir->i_uid)
 628                 goto end_rmdir;
 629         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 630                 goto end_rmdir;
 631         if (!S_ISDIR(inode->i_mode)) {
 632                 retval = -ENOTDIR;
 633                 goto end_rmdir;
 634         }
 635         down(&inode->i_sem);
 636         if (!empty_dir (inode))
 637                 retval = -ENOTEMPTY;
 638         else if (de->inode != inode->i_ino)
 639                 retval = -ENOENT;
 640         else {
 641                 if (inode->i_count > 1) {
 642                 /*
 643                  * Are we deleting the last instance of a busy directory?
 644                  * Better clean up if so.
 645                  *
 646                  * Make directory empty (it will be truncated when finally
 647                  * dereferenced).  This also inhibits ext2_add_entry.
 648                  */
 649                         inode->i_size = 0;
 650                 }
 651                 retval = ext2_delete_entry (de, bh);
 652                 dir->i_version = ++event;
 653         }
 654         up(&inode->i_sem);
 655         if (retval)
 656                 goto end_rmdir;
 657         mark_buffer_dirty(bh, 1);
 658         if (IS_SYNC(dir)) {
 659                 ll_rw_block (WRITE, 1, &bh);
 660                 wait_on_buffer (bh);
 661         }
 662         if (inode->i_nlink != 2)
 663                 ext2_warning (inode->i_sb, "ext2_rmdir",
 664                               "empty directory has nlink!=2 (%d)",
 665                               inode->i_nlink);
 666         inode->i_version = ++event;
 667         inode->i_nlink = 0;
 668         inode->i_dirt = 1;
 669         dir->i_nlink--;
 670         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 671         dir->i_dirt = 1;
 672 end_rmdir:
 673         iput (dir);
 674         iput (inode);
 675         brelse (bh);
 676         return retval;
 677 }
 678 
 679 int ext2_unlink (struct inode * dir, const char * name, int len)
     /*  */
 680 {
 681         int retval;
 682         struct inode * inode;
 683         struct buffer_head * bh;
 684         struct ext2_dir_entry * de;
 685 
 686 repeat:
 687         if (!dir)
 688                 return -ENOENT;
 689         retval = -ENOENT;
 690         inode = NULL;
 691         bh = ext2_find_entry (dir, name, len, &de);
 692         if (!bh)
 693                 goto end_unlink;
 694         if (!(inode = iget (dir->i_sb, de->inode)))
 695                 goto end_unlink;
 696         retval = -EPERM;
 697         if (S_ISDIR(inode->i_mode))
 698                 goto end_unlink;
 699         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 700                 goto end_unlink;
 701         if (de->inode != inode->i_ino) {
 702                 iput(inode);
 703                 brelse(bh);
 704                 current->counter = 0;
 705                 schedule();
 706                 goto repeat;
 707         }
 708         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 709             current->fsuid != inode->i_uid &&
 710             current->fsuid != dir->i_uid)
 711                 goto end_unlink;
 712         if (!inode->i_nlink) {
 713                 ext2_warning (inode->i_sb, "ext2_unlink",
 714                               "Deleting nonexistent file (%lu), %d",
 715                               inode->i_ino, inode->i_nlink);
 716                 inode->i_nlink = 1;
 717         }
 718         retval = ext2_delete_entry (de, bh);
 719         if (retval)
 720                 goto end_unlink;
 721         dir->i_version = ++event;
 722         mark_buffer_dirty(bh, 1);
 723         if (IS_SYNC(dir)) {
 724                 ll_rw_block (WRITE, 1, &bh);
 725                 wait_on_buffer (bh);
 726         }
 727         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 728         dir->i_dirt = 1;
 729         inode->i_nlink--;
 730         inode->i_dirt = 1;
 731         inode->i_ctime = dir->i_ctime;
 732         retval = 0;
 733 end_unlink:
 734         brelse (bh);
 735         iput (inode);
 736         iput (dir);
 737         return retval;
 738 }
 739 
 740 int ext2_symlink (struct inode * dir, const char * name, int len,
     /*  */
 741                   const char * symname)
 742 {
 743         struct ext2_dir_entry * de;
 744         struct inode * inode = NULL;
 745         struct buffer_head * bh = NULL, * name_block = NULL;
 746         char * link;
 747         int i, err;
 748         int l;
 749         char c;
 750 
 751         if (!(inode = ext2_new_inode (dir, S_IFLNK))) {
 752                 iput (dir);
 753                 return -ENOSPC;
 754         }
 755         inode->i_mode = S_IFLNK | S_IRWXUGO;
 756         inode->i_op = &ext2_symlink_inode_operations;
 757         for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
 758              symname [l]; l++)
 759                 ;
 760         if (l >= EXT2_N_BLOCKS * sizeof (unsigned long)) {
 761 
 762                 ext2_debug ("l=%d, normal symlink\n", l);
 763 
 764                 name_block = ext2_bread (inode, 0, 1, &err);
 765                 if (!name_block) {
 766                         iput (dir);
 767                         inode->i_nlink--;
 768                         inode->i_dirt = 1;
 769                         iput (inode);
 770                         return err;
 771                 }
 772                 link = name_block->b_data;
 773         } else {
 774                 link = (char *) inode->u.ext2_i.i_data;
 775 
 776                 ext2_debug ("l=%d, fast symlink\n", l);
 777 
 778         }
 779         i = 0;
 780         while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
 781                 link[i++] = c;
 782         link[i] = 0;
 783         if (name_block) {
 784                 mark_buffer_dirty(name_block, 1);
 785                 brelse (name_block);
 786         }
 787         inode->i_size = i;
 788         inode->i_dirt = 1;
 789         bh = ext2_find_entry (dir, name, len, &de);
 790         if (bh) {
 791                 inode->i_nlink--;
 792                 inode->i_dirt = 1;
 793                 iput (inode);
 794                 brelse (bh);
 795                 iput (dir);
 796                 return -EEXIST;
 797         }
 798         bh = ext2_add_entry (dir, name, len, &de, &err);
 799         if (!bh) {
 800                 inode->i_nlink--;
 801                 inode->i_dirt = 1;
 802                 iput (inode);
 803                 iput (dir);
 804                 return err;
 805         }
 806         de->inode = inode->i_ino;
 807         dir->i_version = ++event;
 808         dcache_add(dir, de->name, de->name_len, de->inode);
 809         mark_buffer_dirty(bh, 1);
 810         if (IS_SYNC(dir)) {
 811                 ll_rw_block (WRITE, 1, &bh);
 812                 wait_on_buffer (bh);
 813         }
 814         brelse (bh);
 815         iput (dir);
 816         iput (inode);
 817         return 0;
 818 }
 819 
 820 int ext2_link (struct inode * oldinode, struct inode * dir,
     /*  */
 821                const char * name, int len)
 822 {
 823         struct ext2_dir_entry * de;
 824         struct buffer_head * bh;
 825         int err;
 826 
 827         if (S_ISDIR(oldinode->i_mode)) {
 828                 iput (oldinode);
 829                 iput (dir);
 830                 return -EPERM;
 831         }
 832         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 833                 iput (oldinode);
 834                 iput (dir);
 835                 return -EPERM;
 836         }
 837         if (oldinode->i_nlink >= EXT2_LINK_MAX) {
 838                 iput (oldinode);
 839                 iput (dir);
 840                 return -EMLINK;
 841         }
 842         bh = ext2_find_entry (dir, name, len, &de);
 843         if (bh) {
 844                 brelse (bh);
 845                 iput (dir);
 846                 iput (oldinode);
 847                 return -EEXIST;
 848         }
 849         bh = ext2_add_entry (dir, name, len, &de, &err);
 850         if (!bh) {
 851                 iput (dir);
 852                 iput (oldinode);
 853                 return err;
 854         }
 855         de->inode = oldinode->i_ino;
 856         dir->i_version = ++event;
 857         dcache_add(dir, de->name, de->name_len, de->inode);
 858         mark_buffer_dirty(bh, 1);
 859         if (IS_SYNC(dir)) {
 860                 ll_rw_block (WRITE, 1, &bh);
 861                 wait_on_buffer (bh);
 862         }
 863         brelse (bh);
 864         iput (dir);
 865         oldinode->i_nlink++;
 866         oldinode->i_ctime = CURRENT_TIME;
 867         oldinode->i_dirt = 1;
 868         iput (oldinode);
 869         return 0;
 870 }
 871 
 872 static int subdir (struct inode * new_inode, struct inode * old_inode)
     /*  */
 873 {
 874         int ino;
 875         int result;
 876 
 877         new_inode->i_count++;
 878         result = 0;
 879         for (;;) {
 880                 if (new_inode == old_inode) {
 881                         result = 1;
 882                         break;
 883                 }
 884                 if (new_inode->i_dev != old_inode->i_dev)
 885                         break;
 886                 ino = new_inode->i_ino;
 887                 if (ext2_lookup (new_inode, "..", 2, &new_inode))
 888                         break;
 889                 if (new_inode->i_ino == ino)
 890                         break;
 891         }
 892         iput (new_inode);
 893         return result;
 894 }
 895 
 896 #define PARENT_INO(buffer) \
 897         ((struct ext2_dir_entry *) ((char *) buffer + \
 898         ((struct ext2_dir_entry *) buffer)->rec_len))->inode
 899 
 900 #define PARENT_NAME(buffer) \
 901         ((struct ext2_dir_entry *) ((char *) buffer + \
 902         ((struct ext2_dir_entry *) buffer)->rec_len))->name
 903 
 904 /*
 905  * rename uses retrying to avoid race-conditions: at least they should be
 906  * minimal.
 907  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 908  * checks fail, it tries to restart itself again. Very practical - no changes
 909  * are done until we know everything works ok.. and then all the changes can be
 910  * done in one fell swoop when we have claimed all the buffers needed.
 911  *
 912  * Anybody can rename anything with this: the permission checks are left to the
 913  * higher-level routines.
 914  */
 915 static int do_ext2_rename (struct inode * old_dir, const char * old_name,
     /*  */
 916                            int old_len, struct inode * new_dir,
 917                            const char * new_name, int new_len)
 918 {
 919         struct inode * old_inode, * new_inode;
 920         struct buffer_head * old_bh, * new_bh, * dir_bh;
 921         struct ext2_dir_entry * old_de, * new_de;
 922         int retval;
 923 
 924         goto start_up;
 925 try_again:
 926         if (new_bh && new_de)
 927                 ext2_delete_entry(new_de, new_bh);
 928         brelse (old_bh);
 929         brelse (new_bh);
 930         brelse (dir_bh);
 931         iput (old_inode);
 932         iput (new_inode);
 933         current->counter = 0;
 934         schedule ();
 935 start_up:
 936         old_inode = new_inode = NULL;
 937         old_bh = new_bh = dir_bh = NULL;
 938         new_de = NULL;
 939         old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
 940         retval = -ENOENT;
 941         if (!old_bh)
 942                 goto end_rename;
 943         old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
 944         if (!old_inode)
 945                 goto end_rename;
 946         retval = -EPERM;
 947         if ((old_dir->i_mode & S_ISVTX) && 
 948             current->fsuid != old_inode->i_uid &&
 949             current->fsuid != old_dir->i_uid && !fsuser())
 950                 goto end_rename;
 951         if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
 952                 goto end_rename;
 953         new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
 954         if (new_bh) {
 955                 new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
 956                 if (!new_inode) {
 957                         brelse (new_bh);
 958                         new_bh = NULL;
 959                 }
 960         }
 961         if (new_inode == old_inode) {
 962                 retval = 0;
 963                 goto end_rename;
 964         }
 965         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 966                 retval = -EISDIR;
 967                 if (!S_ISDIR(old_inode->i_mode))
 968                         goto end_rename;
 969                 retval = -EINVAL;
 970                 if (subdir (new_dir, old_inode))
 971                         goto end_rename;
 972                 retval = -ENOTEMPTY;
 973                 if (!empty_dir (new_inode))
 974                         goto end_rename;
 975                 retval = -EBUSY;
 976                 if (new_inode->i_count > 1)
 977                         goto end_rename;
 978         }
 979         retval = -EPERM;
 980         if (new_inode && (new_dir->i_mode & S_ISVTX) &&
 981             current->fsuid != new_inode->i_uid &&
 982             current->fsuid != new_dir->i_uid && !fsuser())
 983                 goto end_rename;
 984         if (S_ISDIR(old_inode->i_mode)) {
 985                 retval = -ENOTDIR;
 986                 if (new_inode && !S_ISDIR(new_inode->i_mode))
 987                         goto end_rename;
 988                 retval = -EINVAL;
 989                 if (subdir (new_dir, old_inode))
 990                         goto end_rename;
 991                 dir_bh = ext2_bread (old_inode, 0, 0, &retval);
 992                 if (!dir_bh)
 993                         goto end_rename;
 994                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 995                         goto end_rename;
 996                 retval = -EMLINK;
 997                 if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
 998                         goto end_rename;
 999         }
1000         if (!new_bh)
1001                 new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
1002                                          &retval);
1003         if (!new_bh)
1004                 goto end_rename;
1005         /*
1006          * sanity checking before doing the rename - avoid races
1007          */
1008         if (new_inode && (new_de->inode != new_inode->i_ino))
1009                 goto try_again;
1010         if (new_de->inode && !new_inode)
1011                 goto try_again;
1012         if (old_de->inode != old_inode->i_ino)
1013                 goto try_again;
1014         /*
1015          * ok, that's it
1016          */
1017         new_de->inode = old_inode->i_ino;
1018         new_dir->i_version = ++event;
1019         dcache_add(new_dir, new_de->name, new_de->name_len, new_de->inode);
1020         retval = ext2_delete_entry (old_de, old_bh);
1021         if (retval == -ENOENT)
1022                 goto try_again;
1023         if (retval)
1024                 goto end_rename;
1025         old_dir->i_version = ++event;
1026         if (new_inode) {
1027                 new_inode->i_nlink--;
1028                 new_inode->i_ctime = CURRENT_TIME;
1029                 new_inode->i_dirt = 1;
1030         }
1031         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
1032         old_dir->i_dirt = 1;
1033         if (dir_bh) {
1034                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
1035                 dcache_add(old_inode, "..", 2, new_dir->i_ino);
1036                 mark_buffer_dirty(dir_bh, 1);
1037                 old_dir->i_nlink--;
1038                 old_dir->i_dirt = 1;
1039                 if (new_inode) {
1040                         new_inode->i_nlink--;
1041                         new_inode->i_dirt = 1;
1042                 } else {
1043                         new_dir->i_nlink++;
1044                         new_dir->i_dirt = 1;
1045                 }
1046         }
1047         mark_buffer_dirty(old_bh,  1);
1048         if (IS_SYNC(old_dir)) {
1049                 ll_rw_block (WRITE, 1, &old_bh);
1050                 wait_on_buffer (old_bh);
1051         }
1052         mark_buffer_dirty(new_bh, 1);
1053         if (IS_SYNC(new_dir)) {
1054                 ll_rw_block (WRITE, 1, &new_bh);
1055                 wait_on_buffer (new_bh);
1056         }
1057         retval = 0;
1058 end_rename:
1059         brelse (dir_bh);
1060         brelse (old_bh);
1061         brelse (new_bh);
1062         iput (old_inode);
1063         iput (new_inode);
1064         iput (old_dir);
1065         iput (new_dir);
1066         return retval;
1067 }
1068 
1069 /*
1070  * Ok, rename also locks out other renames, as they can change the parent of
1071  * a directory, and we don't want any races. Other races are checked for by
1072  * "do_rename()", which restarts if there are inconsistencies.
1073  *
1074  * Note that there is no race between different filesystems: it's only within
1075  * the same device that races occur: many renames can happen at once, as long
1076  * as they are on different partitions.
1077  *
1078  * In the second extended file system, we use a lock flag stored in the memory
1079  * super-block.  This way, we really lock other renames only if they occur
1080  * on the same file system
1081  */
1082 int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
     /*  */
1083                  struct inode * new_dir, const char * new_name, int new_len)
1084 {
1085         int result;
1086 
1087         while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
1088                 sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1089         old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
1090         result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
1091                                  new_name, new_len);
1092         old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
1093         wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1094         return result;
1095 }
/* */
root/fs/ext2/namei.c

DEFINITIONS
