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  Remy Card (card@masi.ibp.fr)
   5  *
   6  *  from
   7  *
   8  *  linux/fs/minix/namei.c
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  */
  12 
  13 #include <asm/segment.h>
  14 
  15 #include <linux/errno.h>
  16 #include <linux/fs.h>
  17 #include <linux/ext2_fs.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/kernel.h>
  20 #include <linux/sched.h>
  21 #include <linux/stat.h>
  22 #include <linux/string.h>
  23 #include <linux/locks.h>
  24 
  25 /*
  26  * comment out this line if you want names > EXT2_NAME_LEN chars to be
  27  * truncated. Else they will be disallowed.
  28  */
  29 /* #define NO_TRUNCATE */
  30         
  31 /*
  32  * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
  33  */
  34 static int ext2_match (int len, const char * const name,
     /*  */
  35                        struct ext2_dir_entry * de)
  36 {
  37         unsigned char same;
  38 
  39         if (!de || !de->inode || len > EXT2_NAME_LEN)
  40                 return 0;
  41         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  42         if (!len && de->name_len == 1 && (de->name[0] == '.') &&
  43            (de->name[1] == '\0'))
  44                 return 1;
  45         if (len != de->name_len)
  46                 return 0;
  47         __asm__("cld\n\t"
  48                 "repe ; cmpsb\n\t"
  49                 "setz %0"
  50                 :"=q" (same)
  51                 :"S" ((long) name), "D" ((long) de->name), "c" (len)
  52                 :"cx", "di", "si");
  53         return (int) same;
  54 }
  55 
  56 /*
  57  *      ext2_find_entry()
  58  *
  59  * finds an entry in the specified directory with the wanted name. It
  60  * returns the cache buffer in which the entry was found, and the entry
  61  * itself (as a parameter - res_dir). It does NOT read the inode of the
  62  * entry - you'll have to do that yourself if you want to.
  63  *
  64  */
  65 static struct buffer_head * ext2_find_entry (struct inode * dir,
     /*  */
  66                                              const char * const name, int namelen,
  67                                              struct ext2_dir_entry ** res_dir)
  68 {
  69         unsigned long offset;
  70         struct buffer_head * bh;
  71         struct ext2_dir_entry * de;
  72         struct super_block * sb;
  73         int err;
  74 
  75         *res_dir = NULL;
  76         if (!dir)
  77                 return NULL;
  78         sb = dir->i_sb;
  79 #ifdef NO_TRUNCATE
  80         if (namelen > EXT2_NAME_LEN)
  81                 return NULL;
  82 #else
  83         if (namelen > EXT2_NAME_LEN)
  84                 namelen = EXT2_NAME_LEN;
  85 #endif
  86         bh = ext2_bread (dir, 0, 0, &err);
  87         if (!bh)
  88                 return NULL;
  89         offset = 0;
  90         de = (struct ext2_dir_entry *) bh->b_data;
  91         while (offset < dir->i_size) {
  92                 if (!bh || (char *)de >= sb->s_blocksize + bh->b_data) {
  93                         brelse (bh);
  94                         bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 0, &err);
  95                         if (!bh) {
  96                                 offset += sb->s_blocksize;
  97                                 continue;
  98                         }
  99                         de = (struct ext2_dir_entry *) bh->b_data;
 100                 }
 101                 if (! ext2_check_dir_entry ("ext2_find_entry", dir, de, bh,
 102                                             offset)) {
 103                         brelse (bh);
 104                         return NULL;
 105                 }
 106                 if (de->inode != 0 && ext2_match (namelen, name, de)) {
 107                         *res_dir = de;
 108                         return bh;
 109                 }
 110                 offset += de->rec_len;
 111                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 112         }
 113         brelse (bh);
 114         return NULL;
 115 }
 116 
 117 int ext2_lookup (struct inode * dir, const char * name, int len,
     /*  */
 118                  struct inode ** result)
 119 {
 120         unsigned long ino;
 121         struct ext2_dir_entry * de;
 122         struct buffer_head * bh;
 123 
 124         *result = NULL;
 125         if (!dir)
 126                 return -ENOENT;
 127         if (!S_ISDIR(dir->i_mode)) {
 128                 iput (dir);
 129                 return -ENOENT;
 130         }
 131 #ifndef DONT_USE_DCACHE
 132         if (!(ino = ext2_dcache_lookup (dir->i_dev, dir->i_ino, name, len))) {
 133 #endif
 134                 if (!(bh = ext2_find_entry (dir, name, len, &de))) {
 135                         iput (dir);
 136                         return -ENOENT;
 137                 }
 138                 ino = de->inode;
 139 #ifndef DONT_USE_DCACHE
 140                 ext2_dcache_add (dir->i_dev, dir->i_ino, de->name,
 141                                  de->name_len, ino);
 142 #endif
 143                 brelse (bh);
 144 #ifndef DONT_USE_DCACHE
 145         }
 146 #endif
 147         if (!(*result = iget (dir->i_sb, ino))) {
 148                 iput (dir);
 149                 return -EACCES;
 150         }
 151         iput (dir);
 152         return 0;
 153 }
 154 
 155 /*
 156  *      ext2_add_entry()
 157  *
 158  * adds a file entry to the specified directory, using the same
 159  * semantics as ext2_find_entry(). It returns NULL if it failed.
 160  *
 161  * NOTE!! The inode part of 'de' is left at 0 - which means you
 162  * may not sleep between calling this and putting something into
 163  * the entry, as someone else might have used it while you slept.
 164  */
 165 static struct buffer_head * ext2_add_entry (struct inode * dir,
     /*  */
 166                                             const char * name, int namelen,
 167                                             struct ext2_dir_entry ** res_dir,
 168                                             int *err)
 169 {
 170         unsigned long offset;
 171         unsigned short rec_len;
 172         struct buffer_head * bh;
 173         struct ext2_dir_entry * de, * de1;
 174         struct super_block * sb;
 175 
 176         *err = -EINVAL;
 177         *res_dir = NULL;
 178         if (!dir)
 179                 return NULL;
 180         sb = dir->i_sb;
 181 #ifdef NO_TRUNCATE
 182         if (namelen > EXT2_NAME_LEN)
 183                 return NULL;
 184 #else
 185         if (namelen > EXT2_NAME_LEN)
 186                 namelen = EXT2_NAME_LEN;
 187 #endif
 188         if (!namelen)
 189                 return NULL;
 190         /* Is this a busy deleted directory?  Can't create new files 
 191            if so */
 192         if (dir->i_size == 0)
 193         {
 194                 *err = -ENOENT;
 195                 return NULL;
 196         }
 197         bh = ext2_bread (dir, 0, 0, err);
 198         if (!bh)
 199                 return NULL;
 200         rec_len = EXT2_DIR_REC_LEN(namelen);
 201         offset = 0;
 202         de = (struct ext2_dir_entry *) bh->b_data;
 203         *err = -ENOSPC;
 204         while (1) {
 205                 if ((char *)de >= sb->s_blocksize + bh->b_data) {
 206                         brelse (bh);
 207                         bh = NULL;
 208                         bh = ext2_bread (dir, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, err);
 209                         if (!bh)
 210                                 return NULL;
 211                         if (dir->i_size <= offset) {
 212                                 if (dir->i_size == 0) {
 213                                         *err = -ENOENT;
 214                                         return NULL;
 215                                 }
 216 
 217                                 ext2_debug ("creating next block\n");
 218 
 219                                 de = (struct ext2_dir_entry *) bh->b_data;
 220                                 de->inode = 0;
 221                                 de->rec_len = sb->s_blocksize;
 222                                 dir->i_size = offset + sb->s_blocksize;
 223                                 dir->i_dirt = 1;
 224 #if 0 /* XXX don't update any times until successful completion of syscall */
 225                                 dir->i_ctime = CURRENT_TIME;
 226 #endif
 227                         } else {
 228 
 229                                 ext2_debug ("skipping to next block\n");
 230 
 231                                 de = (struct ext2_dir_entry *) bh->b_data;
 232                         }
 233                 }
 234                 if (! ext2_check_dir_entry ("ext2_add_entry", dir, de, bh,
 235                                             offset)) {
 236                         *err = -ENOENT;
 237                         brelse (bh);
 238                         return NULL;
 239                 }
 240                 if (de->inode != 0 && ext2_match (namelen, name, de)) {
 241                                 *err = -EEXIST;
 242                                 brelse (bh);
 243                                 return NULL;
 244                 }
 245                 if ((de->inode == 0 && de->rec_len >= rec_len) ||
 246                     (de->rec_len >= EXT2_DIR_REC_LEN(de->name_len) + rec_len)) {
 247                         offset += de->rec_len;
 248                         if (de->inode) {
 249                                 de1 = (struct ext2_dir_entry *) ((char *) de +
 250                                         EXT2_DIR_REC_LEN(de->name_len));
 251                                 de1->rec_len = de->rec_len -
 252                                         EXT2_DIR_REC_LEN(de->name_len);
 253                                 de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 254                                 de = de1;
 255                         }
 256                         de->inode = 0;
 257                         de->name_len = namelen;
 258                         memcpy (de->name, name, namelen);
 259                         /*
 260                          * XXX shouldn't update any times until successful
 261                          * completion of syscall, but too many callers depend
 262                          * on this.
 263                          *
 264                          * XXX similarly, too many callers depend on
 265                          * ext2_new_inode() setting the times, but error
 266                          * recovery deletes the inode, so the worst that can
 267                          * happen is that the times are slightly out of date
 268                          * and/or different from the directory change time.
 269                          */
 270                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 271                         dir->i_dirt = 1;
 272                         bh->b_dirt = 1;
 273                         *res_dir = de;
 274                         *err = 0;
 275                         return bh;
 276                 }
 277                 offset += de->rec_len;
 278                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 279         }
 280         brelse (bh);
 281         return NULL;
 282 }
 283 
 284 /*
 285  * ext2_delete_entry deletes a directory entry by merging it with the
 286  * previous entry
 287  */
 288 static int ext2_delete_entry (struct ext2_dir_entry * dir,
     /*  */
 289                               struct buffer_head * bh)
 290 {
 291         struct ext2_dir_entry * de, * pde;
 292         int i;
 293 
 294         i = 0;
 295         pde = NULL;
 296         de = (struct ext2_dir_entry *) bh->b_data;
 297         while (i < bh->b_size) {
 298                 if (! ext2_check_dir_entry ("ext2_delete_entry", NULL, 
 299                                             de, bh, i))
 300                         return -EIO;
 301                 if (de == dir)  {
 302                         if (pde)
 303                                 pde->rec_len += dir->rec_len;
 304                         /* XXX - must zero the inode number in every case !! */
 305                         dir->inode = 0;
 306                         return 0;
 307                 }
 308                 i += de->rec_len;
 309                 pde = de;
 310                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 311         }
 312         return -ENOENT;
 313 }
 314 
 315 int ext2_create (struct inode * dir,const char * name, int len, int mode,
     /*  */
 316                  struct inode ** result)
 317 {
 318         struct inode * inode;
 319         struct buffer_head * bh;
 320         struct ext2_dir_entry * de;
 321         int err;
 322 
 323         *result = NULL;
 324         if (!dir)
 325                 return -ENOENT;
 326         inode = ext2_new_inode (dir, mode);
 327         if (!inode) {
 328                 iput (dir);
 329                 return -ENOSPC;
 330         }
 331         inode->i_op = &ext2_file_inode_operations;
 332         inode->i_mode = mode;
 333         inode->i_dirt = 1;
 334         bh = ext2_add_entry (dir, name, len, &de, &err);
 335         if (!bh) {
 336                 inode->i_nlink--;
 337                 inode->i_dirt = 1;
 338                 iput (inode);
 339                 iput (dir);
 340                 return err;
 341         }
 342         de->inode = inode->i_ino;
 343 #ifndef DONT_USE_DCACHE
 344         ext2_dcache_add (dir->i_dev, dir->i_ino, de->name, de->name_len,
 345                          de->inode);
 346 #endif
 347         bh->b_dirt = 1;
 348         if (IS_SYNC(dir)) {
 349                 ll_rw_block (WRITE, 1, &bh);
 350                 wait_on_buffer (bh);
 351         }
 352         brelse (bh);
 353         iput (dir);
 354         *result = inode;
 355         return 0;
 356 }
 357 
 358 int ext2_mknod (struct inode * dir, const char * name, int len, int mode,
     /*  */
 359                 int rdev)
 360 {
 361         struct inode * inode;
 362         struct buffer_head * bh;
 363         struct ext2_dir_entry * de;
 364         int err;
 365 
 366         if (!dir)
 367                 return -ENOENT;
 368         bh = ext2_find_entry (dir, name, len, &de);
 369         if (bh) {
 370                 brelse (bh);
 371                 iput (dir);
 372                 return -EEXIST;
 373         }
 374         inode = ext2_new_inode (dir, mode);
 375         if (!inode) {
 376                 iput (dir);
 377                 return -ENOSPC;
 378         }
 379         inode->i_uid = current->euid;
 380         inode->i_mode = mode;
 381         inode->i_op = NULL;
 382         if (S_ISREG(inode->i_mode))
 383                 inode->i_op = &ext2_file_inode_operations;
 384         else if (S_ISDIR(inode->i_mode)) {
 385                 inode->i_op = &ext2_dir_inode_operations;
 386                 if (dir->i_mode & S_ISGID)
 387                         inode->i_mode |= S_ISGID;
 388         }
 389         else if (S_ISLNK(inode->i_mode))
 390                 inode->i_op = &ext2_symlink_inode_operations;
 391         else if (S_ISCHR(inode->i_mode))
 392                 inode->i_op = &chrdev_inode_operations;
 393         else if (S_ISBLK(inode->i_mode))
 394                 inode->i_op = &blkdev_inode_operations;
 395         else if (S_ISFIFO(inode->i_mode)) 
 396                 init_fifo(inode);
 397         if (S_ISBLK(mode) || S_ISCHR(mode))
 398                 inode->i_rdev = rdev;
 399 #if 0
 400         /*
 401          * XXX we may as well use the times set by ext2_new_inode().  The
 402          * following usually does nothing, but sometimes it invalidates
 403          * inode->i_ctime.
 404          */
 405         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 406 #endif
 407         inode->i_dirt = 1;
 408         bh = ext2_add_entry (dir, name, len, &de, &err);
 409         if (!bh) {
 410                 inode->i_nlink--;
 411                 inode->i_dirt = 1;
 412                 iput (inode);
 413                 iput (dir);
 414                 return err;
 415         }
 416         de->inode = inode->i_ino;
 417 #ifndef DONT_USE_DCACHE
 418         ext2_dcache_add (dir->i_dev, dir->i_ino, de->name, de->name_len,
 419                          de->inode);
 420 #endif
 421         bh->b_dirt = 1;
 422         if (IS_SYNC(dir)) {
 423                 ll_rw_block (WRITE, 1, &bh);
 424                 wait_on_buffer (bh);
 425         }
 426         brelse (bh);
 427         iput (dir);
 428         iput (inode);
 429         return 0;
 430 }
 431 
 432 int ext2_mkdir (struct inode * dir, const char * name, int len, int mode)
     /*  */
 433 {
 434         struct inode * inode;
 435         struct buffer_head * bh, * dir_block;
 436         struct ext2_dir_entry * de;
 437         int err;
 438 
 439         if (!dir)
 440                 return -ENOENT;
 441         bh = ext2_find_entry (dir, name, len, &de);
 442         if (bh) {
 443                 brelse (bh);
 444                 iput (dir);
 445                 return -EEXIST;
 446         }
 447         if (dir->i_nlink >= EXT2_LINK_MAX) {
 448                 iput (dir);
 449                 return -EMLINK;
 450         }
 451         inode = ext2_new_inode (dir, S_IFDIR);
 452         if (!inode) {
 453                 iput (dir);
 454                 return -ENOSPC;
 455         }
 456         inode->i_op = &ext2_dir_inode_operations;
 457         inode->i_size = inode->i_sb->s_blocksize;
 458 #if 0 /* XXX as above */
 459         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 460 #endif
 461         dir_block = ext2_bread (inode, 0, 1, &err);
 462         if (!dir_block) {
 463                 iput (dir);
 464                 inode->i_nlink--;
 465                 inode->i_dirt = 1;
 466                 iput (inode);
 467                 return err;
 468         }
 469         inode->i_blocks = inode->i_sb->s_blocksize / 512;
 470         de = (struct ext2_dir_entry *) dir_block->b_data;
 471         de->inode = inode->i_ino;
 472         de->name_len = 1;
 473         de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 474         strcpy (de->name, ".");
 475         de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 476         de->inode = dir->i_ino;
 477         de->rec_len = inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1);
 478         de->name_len = 2;
 479         strcpy (de->name, "..");
 480         inode->i_nlink = 2;
 481         dir_block->b_dirt = 1;
 482         brelse (dir_block);
 483         inode->i_mode = S_IFDIR | (mode & S_IRWXUGO & ~current->umask);
 484         if (dir->i_mode & S_ISGID)
 485                 inode->i_mode |= S_ISGID;
 486         inode->i_dirt = 1;
 487         bh = ext2_add_entry (dir, name, len, &de, &err);
 488         if (!bh) {
 489                 iput (dir);
 490                 inode->i_nlink = 0;
 491                 inode->i_dirt = 1;
 492                 iput (inode);
 493                 return err;
 494         }
 495         de->inode = inode->i_ino;
 496 #ifndef DONT_USE_DCACHE
 497         ext2_dcache_add (dir->i_dev, dir->i_ino, de->name, de->name_len,
 498                          de->inode);
 499 #endif
 500         bh->b_dirt = 1;
 501         if (IS_SYNC(dir)) {
 502                 ll_rw_block (WRITE, 1, &bh);
 503                 wait_on_buffer (bh);
 504         }
 505         dir->i_nlink++;
 506         dir->i_dirt = 1;
 507         iput (dir);
 508         iput (inode);
 509         brelse (bh);
 510         return 0;
 511 }
 512 
 513 /*
 514  * routine to check that the specified directory is empty (for rmdir)
 515  */
 516 static int empty_dir (struct inode * inode)
     /*  */
 517 {
 518         unsigned long offset;
 519         struct buffer_head * bh;
 520         struct ext2_dir_entry * de, * de1;
 521         struct super_block * sb;
 522         int err;
 523 
 524         sb = inode->i_sb;
 525         if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
 526             !(bh = ext2_bread (inode, 0, 0, &err))) {
 527                 ext2_warning (inode->i_sb, "empty_dir",
 528                               "bad directory (dir %lu)", inode->i_ino);
 529                 return 1;
 530         }
 531         de = (struct ext2_dir_entry *) bh->b_data;
 532         de1 = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 533         if (de->inode != inode->i_ino || !de1->inode || 
 534             strcmp (".", de->name) || strcmp ("..", de1->name)) {
 535                 ext2_warning (inode->i_sb, "empty_dir",
 536                               "bad directory (dir %lu)", inode->i_ino);
 537                 return 1;
 538         }
 539         offset = de->rec_len + de1->rec_len;
 540         de = (struct ext2_dir_entry *) ((char *) de1 + de1->rec_len);
 541         while (offset < inode->i_size ) {
 542                 if ((void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
 543                         brelse (bh);
 544                         bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
 545                         if (!bh) {
 546                                 offset += sb->s_blocksize;
 547                                 continue;
 548                         }
 549                         de = (struct ext2_dir_entry *) bh->b_data;
 550                 }
 551                 if (! ext2_check_dir_entry ("empty_dir", inode, de, bh,
 552                                             offset)) {
 553                         brelse (bh);
 554                         return 1;
 555                 }
 556                 if (de->inode) {
 557                         brelse (bh);
 558                         return 0;
 559                 }
 560                 offset += de->rec_len;
 561                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 562         }
 563         brelse (bh);
 564         return 1;
 565 }
 566 
 567 int ext2_rmdir (struct inode * dir, const char * name, int len)
     /*  */
 568 {
 569         int retval;
 570         struct inode * inode;
 571         struct buffer_head * bh;
 572         struct ext2_dir_entry * de;
 573 
 574 repeat:
 575         if (!dir)
 576                 return -ENOENT;
 577         inode = NULL;
 578         bh = ext2_find_entry (dir, name, len, &de);
 579         retval = -ENOENT;
 580         if (!bh)
 581                 goto end_rmdir;
 582         retval = -EPERM;
 583         if (!(inode = iget (dir->i_sb, de->inode)))
 584                 goto end_rmdir;
 585         if (inode->i_dev != dir->i_dev)
 586                 goto end_rmdir;
 587         if (de->inode != inode->i_ino) {
 588                 iput(inode);
 589                 brelse(bh);
 590                 current->counter = 0;
 591                 schedule();
 592                 goto repeat;
 593         }
 594         if ((dir->i_mode & S_ISVTX) && current->euid &&
 595             inode->i_uid != current->euid)
 596                 goto end_rmdir;
 597         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 598                 goto end_rmdir;
 599         if (!S_ISDIR(inode->i_mode)) {
 600                 retval = -ENOTDIR;
 601                 goto end_rmdir;
 602         }
 603         if (!empty_dir (inode)) {
 604                 retval = -ENOTEMPTY;
 605                 goto end_rmdir;
 606         }
 607         if (de->inode != inode->i_ino) {
 608                 retval = -ENOENT;
 609                 goto end_rmdir;
 610         }
 611         if (inode->i_count > 1) {
 612                 /* Are we deleting the last instance of a busy directory?
 613                    Better clean up if so. */
 614                 /* Make directory empty (it will be truncated when finally
 615                    dereferenced).  This also inhibits ext2_add_entry. */
 616                 inode->i_size = 0;
 617         }
 618         retval = ext2_delete_entry (de, bh);
 619         if (retval)
 620                 goto end_rmdir;
 621         bh->b_dirt = 1;
 622         if (IS_SYNC(dir)) {
 623                 ll_rw_block (WRITE, 1, &bh);
 624                 wait_on_buffer (bh);
 625         }
 626 #ifndef DONT_USE_DCACHE
 627         ext2_dcache_remove(inode->i_dev, inode->i_ino, ".", 1);
 628         ext2_dcache_remove(inode->i_dev, inode->i_ino, "..", 2);
 629 #endif
 630         if (inode->i_nlink != 2)
 631                 ext2_warning (inode->i_sb, "ext2_rmdir",
 632                               "empty directory has nlink!=2 (%d)",
 633                               inode->i_nlink);
 634 #ifndef DONT_USE_DCACHE
 635         ext2_dcache_remove (dir->i_dev, dir->i_ino, de->name, de->name_len);
 636 #endif
 637         inode->i_nlink = 0;
 638         inode->i_dirt = 1;
 639         dir->i_nlink--;
 640         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 641         dir->i_dirt = 1;
 642 end_rmdir:
 643         iput (dir);
 644         iput (inode);
 645         brelse (bh);
 646         return retval;
 647 }
 648 
 649 int ext2_unlink (struct inode * dir, const char * name, int len)
     /*  */
 650 {
 651         int retval;
 652         struct inode * inode;
 653         struct buffer_head * bh;
 654         struct ext2_dir_entry * de;
 655 
 656 repeat:
 657         if (!dir)
 658                 return -ENOENT;
 659         retval = -ENOENT;
 660         inode = NULL;
 661         bh = ext2_find_entry (dir, name, len, &de);
 662         if (!bh)
 663                 goto end_unlink;
 664         if (!(inode = iget (dir->i_sb, de->inode)))
 665                 goto end_unlink;
 666         retval = -EPERM;
 667         if (S_ISDIR(inode->i_mode))
 668                 goto end_unlink;
 669         if (de->inode != inode->i_ino) {
 670                 iput(inode);
 671                 brelse(bh);
 672                 current->counter = 0;
 673                 schedule();
 674                 goto repeat;
 675         }
 676         if ((dir->i_mode & S_ISVTX) && !suser() &&
 677             current->euid != inode->i_uid &&
 678             current->euid != dir->i_uid)
 679                 goto end_unlink;
 680         if (!inode->i_nlink) {
 681                 ext2_warning (inode->i_sb, "ext2_unlink",
 682                               "Deleting nonexistent file (%lu), %d",
 683                               inode->i_ino, inode->i_nlink);
 684                 inode->i_nlink = 1;
 685         }
 686         retval = ext2_delete_entry (de, bh);
 687         if (retval)
 688                 goto end_unlink;
 689         bh->b_dirt = 1;
 690         if (IS_SYNC(dir)) {
 691                 ll_rw_block (WRITE, 1, &bh);
 692                 wait_on_buffer (bh);
 693         }
 694 #ifndef DONT_USE_DCACHE
 695         ext2_dcache_remove (dir->i_dev, dir->i_ino, de->name, de->name_len);
 696 #endif
 697         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 698         dir->i_dirt = 1;
 699         inode->i_nlink--;
 700         inode->i_dirt = 1;
 701         inode->i_ctime = dir->i_ctime;
 702         retval = 0;
 703 end_unlink:
 704         brelse (bh);
 705         iput (inode);
 706         iput (dir);
 707         return retval;
 708 }
 709 
 710 int ext2_symlink (struct inode * dir, const char * name, int len,
     /*  */
 711                   const char * symname)
 712 {
 713         struct ext2_dir_entry * de;
 714         struct inode * inode = NULL;
 715         struct buffer_head * bh = NULL, * name_block = NULL;
 716         char * link;
 717         int i, err;
 718         int l;
 719         char c;
 720 
 721         if (!(inode = ext2_new_inode (dir, S_IFLNK))) {
 722                 iput (dir);
 723                 return -ENOSPC;
 724         }
 725         inode->i_mode = S_IFLNK | S_IRWXUGO;
 726         inode->i_op = &ext2_symlink_inode_operations;
 727         for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
 728              symname [l]; l++)
 729                 ;
 730         if (l >= EXT2_N_BLOCKS * sizeof (unsigned long)) {
 731 
 732                 ext2_debug ("l=%d, normal symlink\n", l);
 733 
 734                 name_block = ext2_bread (inode, 0, 1, &err);
 735                 if (!name_block) {
 736                         iput (dir);
 737                         inode->i_nlink--;
 738                         inode->i_dirt = 1;
 739                         iput (inode);
 740                         return err;
 741                 }
 742                 link = name_block->b_data;
 743         } else {
 744                 link = (char *) inode->u.ext2_i.i_data;
 745 
 746                 ext2_debug ("l=%d, fast symlink\n", l);
 747 
 748         }
 749         i = 0;
 750         while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
 751                 link[i++] = c;
 752         link[i] = 0;
 753         if (name_block) {
 754                 name_block->b_dirt = 1;
 755                 brelse (name_block);
 756         }
 757         inode->i_size = i;
 758         inode->i_dirt = 1;
 759         bh = ext2_find_entry (dir, name, len, &de);
 760         if (bh) {
 761                 inode->i_nlink--;
 762                 inode->i_dirt = 1;
 763                 iput (inode);
 764                 brelse (bh);
 765                 iput (dir);
 766                 return -EEXIST;
 767         }
 768         bh = ext2_add_entry (dir, name, len, &de, &err);
 769         if (!bh) {
 770                 inode->i_nlink--;
 771                 inode->i_dirt = 1;
 772                 iput (inode);
 773                 iput (dir);
 774                 return err;
 775         }
 776         de->inode = inode->i_ino;
 777 #ifndef DONT_USE_DCACHE
 778         ext2_dcache_add (dir->i_dev, dir->i_ino, de->name, de->name_len,
 779                          de->inode);
 780 #endif
 781         bh->b_dirt = 1;
 782         if (IS_SYNC(dir)) {
 783                 ll_rw_block (WRITE, 1, &bh);
 784                 wait_on_buffer (bh);
 785         }
 786         brelse (bh);
 787         iput (dir);
 788         iput (inode);
 789         return 0;
 790 }
 791 
 792 int ext2_link (struct inode * oldinode, struct inode * dir,
     /*  */
 793                const char * name, int len)
 794 {
 795         struct ext2_dir_entry * de;
 796         struct buffer_head * bh;
 797         int err;
 798 
 799         if (S_ISDIR(oldinode->i_mode)) {
 800                 iput (oldinode);
 801                 iput (dir);
 802                 return -EPERM;
 803         }
 804         if (oldinode->i_nlink >= EXT2_LINK_MAX) {
 805                 iput (oldinode);
 806                 iput (dir);
 807                 return -EMLINK;
 808         }
 809         bh = ext2_find_entry (dir, name, len, &de);
 810         if (bh) {
 811                 brelse (bh);
 812                 iput (dir);
 813                 iput (oldinode);
 814                 return -EEXIST;
 815         }
 816         bh = ext2_add_entry (dir, name, len, &de, &err);
 817         if (!bh) {
 818                 iput (dir);
 819                 iput (oldinode);
 820                 return err;
 821         }
 822         de->inode = oldinode->i_ino;
 823 #ifndef DONT_USE_DCACHE
 824         ext2_dcache_add (dir->i_dev, dir->i_ino, de->name, de->name_len,
 825                          de->inode);
 826 #endif
 827         bh->b_dirt = 1;
 828         if (IS_SYNC(dir)) {
 829                 ll_rw_block (WRITE, 1, &bh);
 830                 wait_on_buffer (bh);
 831         }
 832         brelse (bh);
 833         iput (dir);
 834         oldinode->i_nlink++;
 835         oldinode->i_ctime = CURRENT_TIME;
 836         oldinode->i_dirt = 1;
 837         iput (oldinode);
 838         return 0;
 839 }
 840 
 841 static int subdir (struct inode * new_inode, struct inode * old_inode)
     /*  */
 842 {
 843         int ino;
 844         int result;
 845 
 846         new_inode->i_count++;
 847         result = 0;
 848         for (;;) {
 849                 if (new_inode == old_inode) {
 850                         result = 1;
 851                         break;
 852                 }
 853                 if (new_inode->i_dev != old_inode->i_dev)
 854                         break;
 855                 ino = new_inode->i_ino;
 856                 if (ext2_lookup (new_inode, "..", 2, &new_inode))
 857                         break;
 858                 if (new_inode->i_ino == ino)
 859                         break;
 860         }
 861         iput (new_inode);
 862         return result;
 863 }
 864 
 865 #define PARENT_INO(buffer) \
 866         ((struct ext2_dir_entry *) ((char *) buffer + \
 867         ((struct ext2_dir_entry *) buffer)->rec_len))->inode
 868 
 869 #define PARENT_NAME(buffer) \
 870         ((struct ext2_dir_entry *) ((char *) buffer + \
 871         ((struct ext2_dir_entry *) buffer)->rec_len))->name
 872 
 873 /*
 874  * rename uses retrying to avoid race-conditions: at least they should be
 875  * minimal.
 876  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 877  * checks fail, it tries to restart itself again. Very practical - no changes
 878  * are done until we know everything works ok.. and then all the changes can be
 879  * done in one fell swoop when we have claimed all the buffers needed.
 880  *
 881  * Anybody can rename anything with this: the permission checks are left to the
 882  * higher-level routines.
 883  */
 884 static int do_ext2_rename (struct inode * old_dir, const char * old_name,
     /*  */
 885                            int old_len, struct inode * new_dir,
 886                            const char * new_name, int new_len)
 887 {
 888         struct inode * old_inode, * new_inode;
 889         struct buffer_head * old_bh, * new_bh, * dir_bh;
 890         struct ext2_dir_entry * old_de, * new_de;
 891         int retval;
 892 
 893         goto start_up;
 894 try_again:
 895         if (new_bh && new_de)
 896                 ext2_delete_entry(new_de, new_bh);
 897         brelse (old_bh);
 898         brelse (new_bh);
 899         brelse (dir_bh);
 900         iput (old_inode);
 901         iput (new_inode);
 902         current->counter = 0;
 903         schedule ();
 904 start_up:
 905         old_inode = new_inode = NULL;
 906         old_bh = new_bh = dir_bh = NULL;
 907         new_de = NULL;
 908         old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
 909         retval = -ENOENT;
 910         if (!old_bh)
 911                 goto end_rename;
 912         old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
 913         if (!old_inode)
 914                 goto end_rename;
 915         retval = -EPERM;
 916         if ((old_dir->i_mode & S_ISVTX) && 
 917             current->euid != old_inode->i_uid &&
 918             current->euid != old_dir->i_uid && !suser())
 919                 goto end_rename;
 920         new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
 921         if (new_bh) {
 922                 new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
 923                 if (!new_inode) {
 924                         brelse (new_bh);
 925                         new_bh = NULL;
 926                 }
 927         }
 928         if (new_inode == old_inode) {
 929                 retval = 0;
 930                 goto end_rename;
 931         }
 932         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 933                 retval = -EISDIR;
 934                 if (!S_ISDIR(old_inode->i_mode))
 935                         goto end_rename;
 936                 retval = -EINVAL;
 937                 if (subdir (new_dir, old_inode))
 938                         goto end_rename;
 939                 retval = -ENOTEMPTY;
 940                 if (!empty_dir (new_inode))
 941                         goto end_rename;
 942                 retval = -EBUSY;
 943                 if (new_inode->i_count > 1)
 944                         goto end_rename;
 945         }
 946         retval = -EPERM;
 947         if (new_inode && (new_dir->i_mode & S_ISVTX) &&
 948             current->euid != new_inode->i_uid &&
 949             current->euid != new_dir->i_uid && !suser())
 950                 goto end_rename;
 951         if (S_ISDIR(old_inode->i_mode)) {
 952                 retval = -ENOTDIR;
 953                 if (new_inode && !S_ISDIR(new_inode->i_mode))
 954                         goto end_rename;
 955                 retval = -EINVAL;
 956                 if (subdir (new_dir, old_inode))
 957                         goto end_rename;
 958                 dir_bh = ext2_bread (old_inode, 0, 0, &retval);
 959                 if (!dir_bh)
 960                         goto end_rename;
 961                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 962                         goto end_rename;
 963                 retval = -EMLINK;
 964                 if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
 965                         goto end_rename;
 966         }
 967         if (!new_bh)
 968                 new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
 969                                          &retval);
 970         if (!new_bh)
 971                 goto end_rename;
 972 /* sanity checking before doing the rename - avoid races */
 973         if (new_inode && (new_de->inode != new_inode->i_ino))
 974                 goto try_again;
 975         if (new_de->inode && !new_inode)
 976                 goto try_again;
 977         if (old_de->inode != old_inode->i_ino)
 978                 goto try_again;
 979 /* ok, that's it */
 980         new_de->inode = old_inode->i_ino;
 981 #ifndef DONT_USE_DCACHE
 982         ext2_dcache_remove (old_dir->i_dev, old_dir->i_ino, old_de->name,
 983                             old_de->name_len);
 984         ext2_dcache_add (new_dir->i_dev, new_dir->i_ino, new_de->name,
 985                          new_de->name_len, new_de->inode);
 986 #endif
 987         retval = ext2_delete_entry (old_de, old_bh);
 988         if (retval == -ENOENT)
 989                 goto try_again;
 990         if (retval)
 991                 goto end_rename;
 992         if (new_inode) {
 993                 new_inode->i_nlink--;
 994                 new_inode->i_ctime = CURRENT_TIME;
 995                 new_inode->i_dirt = 1;
 996         }
 997         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
 998         old_dir->i_dirt = 1;
 999         old_bh->b_dirt = 1;
1000         if (IS_SYNC(old_dir)) {
1001                 ll_rw_block (WRITE, 1, &old_bh);
1002                 wait_on_buffer (old_bh);
1003         }
1004         new_bh->b_dirt = 1;
1005         if (IS_SYNC(new_dir)) {
1006                 ll_rw_block (WRITE, 1, &new_bh);
1007                 wait_on_buffer (new_bh);
1008         }
1009         if (dir_bh) {
1010                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
1011                 dir_bh->b_dirt = 1;
1012                 old_dir->i_nlink--;
1013                 old_dir->i_dirt = 1;
1014                 if (new_inode) {
1015                         new_inode->i_nlink--;
1016                         new_inode->i_dirt = 1;
1017                 } else {
1018                         new_dir->i_nlink++;
1019                         new_dir->i_dirt = 1;
1020                 }
1021         }
1022         retval = 0;
1023 end_rename:
1024         brelse (dir_bh);
1025         brelse (old_bh);
1026         brelse (new_bh);
1027         iput (old_inode);
1028         iput (new_inode);
1029         iput (old_dir);
1030         iput (new_dir);
1031         return retval;
1032 }
1033 
1034 /*
1035  * Ok, rename also locks out other renames, as they can change the parent of
1036  * a directory, and we don't want any races. Other races are checked for by
1037  * "do_rename()", which restarts if there are inconsistencies.
1038  *
1039  * Note that there is no race between different filesystems: it's only within
1040  * the same device that races occur: many renames can happen at once, as long
1041  * as they are on different partitions.
1042  *
1043  * In the second extended file system, we use a lock flag stored in the memory
1044  * super-block.  This way, we really lock other renames only if they occur
1045  * on the same file system
1046  */
1047 int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
     /*  */
1048                  struct inode * new_dir, const char * new_name, int new_len)
1049 {
1050         int result;
1051 
1052         while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
1053                 sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1054         old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
1055         result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
1056                                  new_name, new_len);
1057         old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
1058         wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1059         return result;
1060 }
/* */
root/fs/ext2/namei.c

DEFINITIONS
