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                         dir->i_version = ++event;
 322                         mark_buffer_dirty(bh, 1);
 323                         *res_dir = de;
 324                         *err = 0;
 325                         return bh;
 326                 }
 327                 offset += de->rec_len;
 328                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 329         }
 330         brelse (bh);
 331         return NULL;
 332 }
 333 
 334 /*
 335  * ext2_delete_entry deletes a directory entry by merging it with the
 336  * previous entry
 337  */
 338 static int ext2_delete_entry (struct ext2_dir_entry * dir,
     /*  */
 339                               struct buffer_head * bh)
 340 {
 341         struct ext2_dir_entry * de, * pde;
 342         int i;
 343 
 344         i = 0;
 345         pde = NULL;
 346         de = (struct ext2_dir_entry *) bh->b_data;
 347         while (i < bh->b_size) {
 348                 if (!ext2_check_dir_entry ("ext2_delete_entry", NULL, 
 349                                            de, bh, i))
 350                         return -EIO;
 351                 if (de == dir)  {
 352                         if (pde)
 353                                 pde->rec_len += dir->rec_len;
 354                         dir->inode = 0;
 355                         return 0;
 356                 }
 357                 i += de->rec_len;
 358                 pde = de;
 359                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 360         }
 361         return -ENOENT;
 362 }
 363 
 364 int ext2_create (struct inode * dir,const char * name, int len, int mode,
     /*  */
 365                  struct inode ** result)
 366 {
 367         struct inode * inode;
 368         struct buffer_head * bh;
 369         struct ext2_dir_entry * de;
 370         int err;
 371 
 372         *result = NULL;
 373         if (!dir)
 374                 return -ENOENT;
 375         inode = ext2_new_inode (dir, mode);
 376         if (!inode) {
 377                 iput (dir);
 378                 return -ENOSPC;
 379         }
 380         inode->i_op = &ext2_file_inode_operations;
 381         inode->i_mode = mode;
 382         inode->i_dirt = 1;
 383         bh = ext2_add_entry (dir, name, len, &de, &err);
 384         if (!bh) {
 385                 inode->i_nlink--;
 386                 inode->i_dirt = 1;
 387                 iput (inode);
 388                 iput (dir);
 389                 return err;
 390         }
 391         de->inode = inode->i_ino;
 392         dir->i_version = ++event;
 393         dcache_add(dir, de->name, de->name_len, de->inode);
 394         mark_buffer_dirty(bh, 1);
 395         if (IS_SYNC(dir)) {
 396                 ll_rw_block (WRITE, 1, &bh);
 397                 wait_on_buffer (bh);
 398         }
 399         brelse (bh);
 400         iput (dir);
 401         *result = inode;
 402         return 0;
 403 }
 404 
 405 int ext2_mknod (struct inode * dir, const char * name, int len, int mode,
     /*  */
 406                 int rdev)
 407 {
 408         struct inode * inode;
 409         struct buffer_head * bh;
 410         struct ext2_dir_entry * de;
 411         int err;
 412 
 413         if (!dir)
 414                 return -ENOENT;
 415         bh = ext2_find_entry (dir, name, len, &de);
 416         if (bh) {
 417                 brelse (bh);
 418                 iput (dir);
 419                 return -EEXIST;
 420         }
 421         inode = ext2_new_inode (dir, mode);
 422         if (!inode) {
 423                 iput (dir);
 424                 return -ENOSPC;
 425         }
 426         inode->i_uid = current->fsuid;
 427         inode->i_mode = mode;
 428         inode->i_op = NULL;
 429         if (S_ISREG(inode->i_mode))
 430                 inode->i_op = &ext2_file_inode_operations;
 431         else if (S_ISDIR(inode->i_mode)) {
 432                 inode->i_op = &ext2_dir_inode_operations;
 433                 if (dir->i_mode & S_ISGID)
 434                         inode->i_mode |= S_ISGID;
 435         }
 436         else if (S_ISLNK(inode->i_mode))
 437                 inode->i_op = &ext2_symlink_inode_operations;
 438         else if (S_ISCHR(inode->i_mode))
 439                 inode->i_op = &chrdev_inode_operations;
 440         else if (S_ISBLK(inode->i_mode))
 441                 inode->i_op = &blkdev_inode_operations;
 442         else if (S_ISFIFO(inode->i_mode)) 
 443                 init_fifo(inode);
 444         if (S_ISBLK(mode) || S_ISCHR(mode))
 445                 inode->i_rdev = rdev;
 446         inode->i_dirt = 1;
 447         bh = ext2_add_entry (dir, name, len, &de, &err);
 448         if (!bh) {
 449                 inode->i_nlink--;
 450                 inode->i_dirt = 1;
 451                 iput (inode);
 452                 iput (dir);
 453                 return err;
 454         }
 455         de->inode = inode->i_ino;
 456         dir->i_version = ++event;
 457         dcache_add(dir, de->name, de->name_len, de->inode);
 458         mark_buffer_dirty(bh, 1);
 459         if (IS_SYNC(dir)) {
 460                 ll_rw_block (WRITE, 1, &bh);
 461                 wait_on_buffer (bh);
 462         }
 463         brelse (bh);
 464         iput (dir);
 465         iput (inode);
 466         return 0;
 467 }
 468 
 469 int ext2_mkdir (struct inode * dir, const char * name, int len, int mode)
     /*  */
 470 {
 471         struct inode * inode;
 472         struct buffer_head * bh, * dir_block;
 473         struct ext2_dir_entry * de;
 474         int err;
 475 
 476         if (!dir)
 477                 return -ENOENT;
 478         bh = ext2_find_entry (dir, name, len, &de);
 479         if (bh) {
 480                 brelse (bh);
 481                 iput (dir);
 482                 return -EEXIST;
 483         }
 484         if (dir->i_nlink >= EXT2_LINK_MAX) {
 485                 iput (dir);
 486                 return -EMLINK;
 487         }
 488         inode = ext2_new_inode (dir, S_IFDIR);
 489         if (!inode) {
 490                 iput (dir);
 491                 return -ENOSPC;
 492         }
 493         inode->i_op = &ext2_dir_inode_operations;
 494         inode->i_size = inode->i_sb->s_blocksize;
 495         dir_block = ext2_bread (inode, 0, 1, &err);
 496         if (!dir_block) {
 497                 iput (dir);
 498                 inode->i_nlink--;
 499                 inode->i_dirt = 1;
 500                 iput (inode);
 501                 return err;
 502         }
 503         inode->i_blocks = inode->i_sb->s_blocksize / 512;
 504         de = (struct ext2_dir_entry *) dir_block->b_data;
 505         de->inode = inode->i_ino;
 506         de->name_len = 1;
 507         de->rec_len = EXT2_DIR_REC_LEN(de->name_len);
 508         strcpy (de->name, ".");
 509         de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 510         de->inode = dir->i_ino;
 511         de->rec_len = inode->i_sb->s_blocksize - EXT2_DIR_REC_LEN(1);
 512         de->name_len = 2;
 513         strcpy (de->name, "..");
 514         inode->i_nlink = 2;
 515         mark_buffer_dirty(dir_block, 1);
 516         brelse (dir_block);
 517         inode->i_mode = S_IFDIR | (mode & S_IRWXUGO & ~current->fs->umask);
 518         if (dir->i_mode & S_ISGID)
 519                 inode->i_mode |= S_ISGID;
 520         inode->i_dirt = 1;
 521         bh = ext2_add_entry (dir, name, len, &de, &err);
 522         if (!bh) {
 523                 iput (dir);
 524                 inode->i_nlink = 0;
 525                 inode->i_dirt = 1;
 526                 iput (inode);
 527                 return err;
 528         }
 529         de->inode = inode->i_ino;
 530         dir->i_version = ++event;
 531         dcache_add(dir, de->name, de->name_len, de->inode);
 532         mark_buffer_dirty(bh, 1);
 533         if (IS_SYNC(dir)) {
 534                 ll_rw_block (WRITE, 1, &bh);
 535                 wait_on_buffer (bh);
 536         }
 537         dir->i_nlink++;
 538         dir->i_dirt = 1;
 539         iput (dir);
 540         iput (inode);
 541         brelse (bh);
 542         return 0;
 543 }
 544 
 545 /*
 546  * routine to check that the specified directory is empty (for rmdir)
 547  */
 548 static int empty_dir (struct inode * inode)
     /*  */
 549 {
 550         unsigned long offset;
 551         struct buffer_head * bh;
 552         struct ext2_dir_entry * de, * de1;
 553         struct super_block * sb;
 554         int err;
 555 
 556         sb = inode->i_sb;
 557         if (inode->i_size < EXT2_DIR_REC_LEN(1) + EXT2_DIR_REC_LEN(2) ||
 558             !(bh = ext2_bread (inode, 0, 0, &err))) {
 559                 ext2_warning (inode->i_sb, "empty_dir",
 560                               "bad directory (dir %lu)", inode->i_ino);
 561                 return 1;
 562         }
 563         de = (struct ext2_dir_entry *) bh->b_data;
 564         de1 = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 565         if (de->inode != inode->i_ino || !de1->inode || 
 566             strcmp (".", de->name) || strcmp ("..", de1->name)) {
 567                 ext2_warning (inode->i_sb, "empty_dir",
 568                               "bad directory (dir %lu)", inode->i_ino);
 569                 return 1;
 570         }
 571         offset = de->rec_len + de1->rec_len;
 572         de = (struct ext2_dir_entry *) ((char *) de1 + de1->rec_len);
 573         while (offset < inode->i_size ) {
 574                 if ((void *) de >= (void *) (bh->b_data + sb->s_blocksize)) {
 575                         brelse (bh);
 576                         bh = ext2_bread (inode, offset >> EXT2_BLOCK_SIZE_BITS(sb), 1, &err);
 577                         if (!bh) {
 578                                 offset += sb->s_blocksize;
 579                                 continue;
 580                         }
 581                         de = (struct ext2_dir_entry *) bh->b_data;
 582                 }
 583                 if (!ext2_check_dir_entry ("empty_dir", inode, de, bh,
 584                                            offset)) {
 585                         brelse (bh);
 586                         return 1;
 587                 }
 588                 if (de->inode) {
 589                         brelse (bh);
 590                         return 0;
 591                 }
 592                 offset += de->rec_len;
 593                 de = (struct ext2_dir_entry *) ((char *) de + de->rec_len);
 594         }
 595         brelse (bh);
 596         return 1;
 597 }
 598 
 599 int ext2_rmdir (struct inode * dir, const char * name, int len)
     /*  */
 600 {
 601         int retval;
 602         struct inode * inode;
 603         struct buffer_head * bh;
 604         struct ext2_dir_entry * de;
 605 
 606 repeat:
 607         if (!dir)
 608                 return -ENOENT;
 609         inode = NULL;
 610         bh = ext2_find_entry (dir, name, len, &de);
 611         retval = -ENOENT;
 612         if (!bh)
 613                 goto end_rmdir;
 614         retval = -EPERM;
 615         if (!(inode = iget (dir->i_sb, de->inode)))
 616                 goto end_rmdir;
 617         if (inode->i_dev != dir->i_dev)
 618                 goto end_rmdir;
 619         if (de->inode != inode->i_ino) {
 620                 iput(inode);
 621                 brelse(bh);
 622                 current->counter = 0;
 623                 schedule();
 624                 goto repeat;
 625         }
 626         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 627             current->fsuid != inode->i_uid &&
 628             current->fsuid != dir->i_uid)
 629                 goto end_rmdir;
 630         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 631                 goto end_rmdir;
 632         if (!S_ISDIR(inode->i_mode)) {
 633                 retval = -ENOTDIR;
 634                 goto end_rmdir;
 635         }
 636         down(&inode->i_sem);
 637         if (!empty_dir (inode))
 638                 retval = -ENOTEMPTY;
 639         else if (de->inode != inode->i_ino)
 640                 retval = -ENOENT;
 641         else {
 642                 if (inode->i_count > 1) {
 643                 /*
 644                  * Are we deleting the last instance of a busy directory?
 645                  * Better clean up if so.
 646                  *
 647                  * Make directory empty (it will be truncated when finally
 648                  * dereferenced).  This also inhibits ext2_add_entry.
 649                  */
 650                         inode->i_size = 0;
 651                 }
 652                 retval = ext2_delete_entry (de, bh);
 653                 dir->i_version = ++event;
 654         }
 655         up(&inode->i_sem);
 656         if (retval)
 657                 goto end_rmdir;
 658         mark_buffer_dirty(bh, 1);
 659         if (IS_SYNC(dir)) {
 660                 ll_rw_block (WRITE, 1, &bh);
 661                 wait_on_buffer (bh);
 662         }
 663         if (inode->i_nlink != 2)
 664                 ext2_warning (inode->i_sb, "ext2_rmdir",
 665                               "empty directory has nlink!=2 (%d)",
 666                               inode->i_nlink);
 667         inode->i_version = ++event;
 668         inode->i_nlink = 0;
 669         inode->i_dirt = 1;
 670         dir->i_nlink--;
 671         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 672         dir->i_dirt = 1;
 673 end_rmdir:
 674         iput (dir);
 675         iput (inode);
 676         brelse (bh);
 677         return retval;
 678 }
 679 
 680 int ext2_unlink (struct inode * dir, const char * name, int len)
     /*  */
 681 {
 682         int retval;
 683         struct inode * inode;
 684         struct buffer_head * bh;
 685         struct ext2_dir_entry * de;
 686 
 687 repeat:
 688         if (!dir)
 689                 return -ENOENT;
 690         retval = -ENOENT;
 691         inode = NULL;
 692         bh = ext2_find_entry (dir, name, len, &de);
 693         if (!bh)
 694                 goto end_unlink;
 695         if (!(inode = iget (dir->i_sb, de->inode)))
 696                 goto end_unlink;
 697         retval = -EPERM;
 698         if (S_ISDIR(inode->i_mode))
 699                 goto end_unlink;
 700         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
 701                 goto end_unlink;
 702         if (de->inode != inode->i_ino) {
 703                 iput(inode);
 704                 brelse(bh);
 705                 current->counter = 0;
 706                 schedule();
 707                 goto repeat;
 708         }
 709         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 710             current->fsuid != inode->i_uid &&
 711             current->fsuid != dir->i_uid)
 712                 goto end_unlink;
 713         if (!inode->i_nlink) {
 714                 ext2_warning (inode->i_sb, "ext2_unlink",
 715                               "Deleting nonexistent file (%lu), %d",
 716                               inode->i_ino, inode->i_nlink);
 717                 inode->i_nlink = 1;
 718         }
 719         retval = ext2_delete_entry (de, bh);
 720         if (retval)
 721                 goto end_unlink;
 722         dir->i_version = ++event;
 723         mark_buffer_dirty(bh, 1);
 724         if (IS_SYNC(dir)) {
 725                 ll_rw_block (WRITE, 1, &bh);
 726                 wait_on_buffer (bh);
 727         }
 728         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 729         dir->i_dirt = 1;
 730         inode->i_nlink--;
 731         inode->i_dirt = 1;
 732         inode->i_ctime = dir->i_ctime;
 733         retval = 0;
 734 end_unlink:
 735         brelse (bh);
 736         iput (inode);
 737         iput (dir);
 738         return retval;
 739 }
 740 
 741 int ext2_symlink (struct inode * dir, const char * name, int len,
     /*  */
 742                   const char * symname)
 743 {
 744         struct ext2_dir_entry * de;
 745         struct inode * inode = NULL;
 746         struct buffer_head * bh = NULL, * name_block = NULL;
 747         char * link;
 748         int i, err;
 749         int l;
 750         char c;
 751 
 752         if (!(inode = ext2_new_inode (dir, S_IFLNK))) {
 753                 iput (dir);
 754                 return -ENOSPC;
 755         }
 756         inode->i_mode = S_IFLNK | S_IRWXUGO;
 757         inode->i_op = &ext2_symlink_inode_operations;
 758         for (l = 0; l < inode->i_sb->s_blocksize - 1 &&
 759              symname [l]; l++)
 760                 ;
 761         if (l >= EXT2_N_BLOCKS * sizeof (unsigned long)) {
 762 
 763                 ext2_debug ("l=%d, normal symlink\n", l);
 764 
 765                 name_block = ext2_bread (inode, 0, 1, &err);
 766                 if (!name_block) {
 767                         iput (dir);
 768                         inode->i_nlink--;
 769                         inode->i_dirt = 1;
 770                         iput (inode);
 771                         return err;
 772                 }
 773                 link = name_block->b_data;
 774         } else {
 775                 link = (char *) inode->u.ext2_i.i_data;
 776 
 777                 ext2_debug ("l=%d, fast symlink\n", l);
 778 
 779         }
 780         i = 0;
 781         while (i < inode->i_sb->s_blocksize - 1 && (c = *(symname++)))
 782                 link[i++] = c;
 783         link[i] = 0;
 784         if (name_block) {
 785                 mark_buffer_dirty(name_block, 1);
 786                 brelse (name_block);
 787         }
 788         inode->i_size = i;
 789         inode->i_dirt = 1;
 790         bh = ext2_find_entry (dir, name, len, &de);
 791         if (bh) {
 792                 inode->i_nlink--;
 793                 inode->i_dirt = 1;
 794                 iput (inode);
 795                 brelse (bh);
 796                 iput (dir);
 797                 return -EEXIST;
 798         }
 799         bh = ext2_add_entry (dir, name, len, &de, &err);
 800         if (!bh) {
 801                 inode->i_nlink--;
 802                 inode->i_dirt = 1;
 803                 iput (inode);
 804                 iput (dir);
 805                 return err;
 806         }
 807         de->inode = inode->i_ino;
 808         dir->i_version = ++event;
 809         dcache_add(dir, de->name, de->name_len, de->inode);
 810         mark_buffer_dirty(bh, 1);
 811         if (IS_SYNC(dir)) {
 812                 ll_rw_block (WRITE, 1, &bh);
 813                 wait_on_buffer (bh);
 814         }
 815         brelse (bh);
 816         iput (dir);
 817         iput (inode);
 818         return 0;
 819 }
 820 
 821 int ext2_link (struct inode * oldinode, struct inode * dir,
     /*  */
 822                const char * name, int len)
 823 {
 824         struct ext2_dir_entry * de;
 825         struct buffer_head * bh;
 826         int err;
 827 
 828         if (S_ISDIR(oldinode->i_mode)) {
 829                 iput (oldinode);
 830                 iput (dir);
 831                 return -EPERM;
 832         }
 833         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 834                 iput (oldinode);
 835                 iput (dir);
 836                 return -EPERM;
 837         }
 838         if (oldinode->i_nlink >= EXT2_LINK_MAX) {
 839                 iput (oldinode);
 840                 iput (dir);
 841                 return -EMLINK;
 842         }
 843         bh = ext2_find_entry (dir, name, len, &de);
 844         if (bh) {
 845                 brelse (bh);
 846                 iput (dir);
 847                 iput (oldinode);
 848                 return -EEXIST;
 849         }
 850         bh = ext2_add_entry (dir, name, len, &de, &err);
 851         if (!bh) {
 852                 iput (dir);
 853                 iput (oldinode);
 854                 return err;
 855         }
 856         de->inode = oldinode->i_ino;
 857         dir->i_version = ++event;
 858         dcache_add(dir, de->name, de->name_len, de->inode);
 859         mark_buffer_dirty(bh, 1);
 860         if (IS_SYNC(dir)) {
 861                 ll_rw_block (WRITE, 1, &bh);
 862                 wait_on_buffer (bh);
 863         }
 864         brelse (bh);
 865         iput (dir);
 866         oldinode->i_nlink++;
 867         oldinode->i_ctime = CURRENT_TIME;
 868         oldinode->i_dirt = 1;
 869         iput (oldinode);
 870         return 0;
 871 }
 872 
 873 static int subdir (struct inode * new_inode, struct inode * old_inode)
     /*  */
 874 {
 875         int ino;
 876         int result;
 877 
 878         new_inode->i_count++;
 879         result = 0;
 880         for (;;) {
 881                 if (new_inode == old_inode) {
 882                         result = 1;
 883                         break;
 884                 }
 885                 if (new_inode->i_dev != old_inode->i_dev)
 886                         break;
 887                 ino = new_inode->i_ino;
 888                 if (ext2_lookup (new_inode, "..", 2, &new_inode))
 889                         break;
 890                 if (new_inode->i_ino == ino)
 891                         break;
 892         }
 893         iput (new_inode);
 894         return result;
 895 }
 896 
 897 #define PARENT_INO(buffer) \
 898         ((struct ext2_dir_entry *) ((char *) buffer + \
 899         ((struct ext2_dir_entry *) buffer)->rec_len))->inode
 900 
 901 #define PARENT_NAME(buffer) \
 902         ((struct ext2_dir_entry *) ((char *) buffer + \
 903         ((struct ext2_dir_entry *) buffer)->rec_len))->name
 904 
 905 /*
 906  * rename uses retrying to avoid race-conditions: at least they should be
 907  * minimal.
 908  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 909  * checks fail, it tries to restart itself again. Very practical - no changes
 910  * are done until we know everything works ok.. and then all the changes can be
 911  * done in one fell swoop when we have claimed all the buffers needed.
 912  *
 913  * Anybody can rename anything with this: the permission checks are left to the
 914  * higher-level routines.
 915  */
 916 static int do_ext2_rename (struct inode * old_dir, const char * old_name,
     /*  */
 917                            int old_len, struct inode * new_dir,
 918                            const char * new_name, int new_len)
 919 {
 920         struct inode * old_inode, * new_inode;
 921         struct buffer_head * old_bh, * new_bh, * dir_bh;
 922         struct ext2_dir_entry * old_de, * new_de;
 923         int retval;
 924 
 925         goto start_up;
 926 try_again:
 927         if (new_bh && new_de) {
 928                 ext2_delete_entry(new_de, new_bh);
 929                 new_dir->i_version = ++event;
 930         }
 931         brelse (old_bh);
 932         brelse (new_bh);
 933         brelse (dir_bh);
 934         iput (old_inode);
 935         iput (new_inode);
 936         current->counter = 0;
 937         schedule ();
 938 start_up:
 939         old_inode = new_inode = NULL;
 940         old_bh = new_bh = dir_bh = NULL;
 941         new_de = NULL;
 942         old_bh = ext2_find_entry (old_dir, old_name, old_len, &old_de);
 943         retval = -ENOENT;
 944         if (!old_bh)
 945                 goto end_rename;
 946         old_inode = __iget (old_dir->i_sb, old_de->inode, 0); /* don't cross mnt-points */
 947         if (!old_inode)
 948                 goto end_rename;
 949         retval = -EPERM;
 950         if ((old_dir->i_mode & S_ISVTX) && 
 951             current->fsuid != old_inode->i_uid &&
 952             current->fsuid != old_dir->i_uid && !fsuser())
 953                 goto end_rename;
 954         if (IS_APPEND(old_inode) || IS_IMMUTABLE(old_inode))
 955                 goto end_rename;
 956         new_bh = ext2_find_entry (new_dir, new_name, new_len, &new_de);
 957         if (new_bh) {
 958                 new_inode = __iget (new_dir->i_sb, new_de->inode, 0); /* no mntp cross */
 959                 if (!new_inode) {
 960                         brelse (new_bh);
 961                         new_bh = NULL;
 962                 }
 963         }
 964         if (new_inode == old_inode) {
 965                 retval = 0;
 966                 goto end_rename;
 967         }
 968         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 969                 retval = -EISDIR;
 970                 if (!S_ISDIR(old_inode->i_mode))
 971                         goto end_rename;
 972                 retval = -EINVAL;
 973                 if (subdir (new_dir, old_inode))
 974                         goto end_rename;
 975                 retval = -ENOTEMPTY;
 976                 if (!empty_dir (new_inode))
 977                         goto end_rename;
 978                 retval = -EBUSY;
 979                 if (new_inode->i_count > 1)
 980                         goto end_rename;
 981         }
 982         retval = -EPERM;
 983         if (new_inode && (new_dir->i_mode & S_ISVTX) &&
 984             current->fsuid != new_inode->i_uid &&
 985             current->fsuid != new_dir->i_uid && !fsuser())
 986                 goto end_rename;
 987         if (S_ISDIR(old_inode->i_mode)) {
 988                 retval = -ENOTDIR;
 989                 if (new_inode && !S_ISDIR(new_inode->i_mode))
 990                         goto end_rename;
 991                 retval = -EINVAL;
 992                 if (subdir (new_dir, old_inode))
 993                         goto end_rename;
 994                 dir_bh = ext2_bread (old_inode, 0, 0, &retval);
 995                 if (!dir_bh)
 996                         goto end_rename;
 997                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 998                         goto end_rename;
 999                 retval = -EMLINK;
1000                 if (!new_inode && new_dir->i_nlink >= EXT2_LINK_MAX)
1001                         goto end_rename;
1002         }
1003         if (!new_bh)
1004                 new_bh = ext2_add_entry (new_dir, new_name, new_len, &new_de,
1005                                          &retval);
1006         if (!new_bh)
1007                 goto end_rename;
1008         new_dir->i_version = ++event;
1009         /*
1010          * sanity checking before doing the rename - avoid races
1011          */
1012         if (new_inode && (new_de->inode != new_inode->i_ino))
1013                 goto try_again;
1014         if (new_de->inode && !new_inode)
1015                 goto try_again;
1016         if (old_de->inode != old_inode->i_ino)
1017                 goto try_again;
1018         /*
1019          * ok, that's it
1020          */
1021         new_de->inode = old_inode->i_ino;
1022         dcache_add(new_dir, new_de->name, new_de->name_len, new_de->inode);
1023         retval = ext2_delete_entry (old_de, old_bh);
1024         if (retval == -ENOENT)
1025                 goto try_again;
1026         if (retval)
1027                 goto end_rename;
1028         old_dir->i_version = ++event;
1029         if (new_inode) {
1030                 new_inode->i_nlink--;
1031                 new_inode->i_ctime = CURRENT_TIME;
1032                 new_inode->i_dirt = 1;
1033         }
1034         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME;
1035         old_dir->i_dirt = 1;
1036         if (dir_bh) {
1037                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
1038                 dcache_add(old_inode, "..", 2, new_dir->i_ino);
1039                 mark_buffer_dirty(dir_bh, 1);
1040                 old_dir->i_nlink--;
1041                 old_dir->i_dirt = 1;
1042                 if (new_inode) {
1043                         new_inode->i_nlink--;
1044                         new_inode->i_dirt = 1;
1045                 } else {
1046                         new_dir->i_nlink++;
1047                         new_dir->i_dirt = 1;
1048                 }
1049         }
1050         mark_buffer_dirty(old_bh,  1);
1051         if (IS_SYNC(old_dir)) {
1052                 ll_rw_block (WRITE, 1, &old_bh);
1053                 wait_on_buffer (old_bh);
1054         }
1055         mark_buffer_dirty(new_bh, 1);
1056         if (IS_SYNC(new_dir)) {
1057                 ll_rw_block (WRITE, 1, &new_bh);
1058                 wait_on_buffer (new_bh);
1059         }
1060         retval = 0;
1061 end_rename:
1062         brelse (dir_bh);
1063         brelse (old_bh);
1064         brelse (new_bh);
1065         iput (old_inode);
1066         iput (new_inode);
1067         iput (old_dir);
1068         iput (new_dir);
1069         return retval;
1070 }
1071 
1072 /*
1073  * Ok, rename also locks out other renames, as they can change the parent of
1074  * a directory, and we don't want any races. Other races are checked for by
1075  * "do_rename()", which restarts if there are inconsistencies.
1076  *
1077  * Note that there is no race between different filesystems: it's only within
1078  * the same device that races occur: many renames can happen at once, as long
1079  * as they are on different partitions.
1080  *
1081  * In the second extended file system, we use a lock flag stored in the memory
1082  * super-block.  This way, we really lock other renames only if they occur
1083  * on the same file system
1084  */
1085 int ext2_rename (struct inode * old_dir, const char * old_name, int old_len,
     /*  */
1086                  struct inode * new_dir, const char * new_name, int new_len)
1087 {
1088         int result;
1089 
1090         while (old_dir->i_sb->u.ext2_sb.s_rename_lock)
1091                 sleep_on (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1092         old_dir->i_sb->u.ext2_sb.s_rename_lock = 1;
1093         result = do_ext2_rename (old_dir, old_name, old_len, new_dir,
1094                                  new_name, new_len);
1095         old_dir->i_sb->u.ext2_sb.s_rename_lock = 0;
1096         wake_up (&old_dir->i_sb->u.ext2_sb.s_rename_wait);
1097         return result;
1098 }
/* */
root/fs/ext2/namei.c

DEFINITIONS
