root/fs/ext/namei.c

/* */

DEFINITIONS

1. ext_match
2. ext_find_entry
3. ext_lookup
4. ext_add_entry
5. ext_create
6. ext_mknod
7. ext_mkdir
8. empty_dir
9. ext_merge_entries
10. ext_rmdir
11. ext_unlink
12. ext_symlink
13. ext_link
14. subdir
15. do_ext_rename
16. ext_rename

   1 /*
   2  *  linux/fs/ext/namei.c
   3  *
   4  *  Copyright (C) 1992  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 <linux/sched.h>
  14 #include <linux/ext_fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/string.h>
  17 #include <linux/stat.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/errno.h>
  20 
  21 #include <asm/segment.h>
  22 
  23 /*
  24  * comment out this line if you want names > EXT_NAME_LEN chars to be
  25  * truncated. Else they will be disallowed.
  26  */
  27 /* #define NO_TRUNCATE */
  28 
  29 /*
  30  * EXT_DIR_PAD defines the directory entries boundaries
  31  *
  32  * NOTE: It must be a power of 2 and must be greater or equal than 8
  33  * because a directory entry needs 8 bytes for its fixed part
  34  * (4 bytes for the inode, 2 bytes for the entry length and 2 bytes
  35  * for the name length)
  36  */
  37 #define EXT_DIR_PAD 8
  38 
  39 /*
  40  *
  41  * EXT_DIR_MIN_SIZE is the minimal size of a directory entry
  42  *
  43  * During allocations, a directory entry is split into 2 ones
  44  * *ONLY* if the size of the unused part is greater than or 
  45  * equal to EXT_DIR_MIN_SIZE
  46  */
  47 #define EXT_DIR_MIN_SIZE 12
  48 
  49 /*
  50  * ok, we cannot use strncmp, as the name is not in our data space.
  51  * Thus we'll have to use ext_match. No big problem. Match also makes
  52  * some sanity tests.
  53  *
  54  * NOTE! unlike strncmp, ext_match returns 1 for success, 0 for failure.
  55  */
  56 static int ext_match(int len,const char * name,struct ext_dir_entry * de)
     /*  */
  57 {
  58         if (!de || !de->inode || len > EXT_NAME_LEN)
  59                 return 0;
  60         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  61         if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
  62                 return 1;
  63         if (len != de->name_len)
  64                 return 0;
  65         return !memcmp(name, de->name, len);
  66 }
  67 
  68 /*
  69  *      ext_find_entry()
  70  *
  71  * finds an entry in the specified directory with the wanted name. It
  72  * returns the cache buffer in which the entry was found, and the entry
  73  * itself (as a parameter - res_dir). It does NOT read the inode of the
  74  * entry - you'll have to do that yourself if you want to.
  75  *
  76  * addition for the ext file system : this function returns the previous
  77  * and next directory entries in the parameters prev_dir and next_dir
  78  */
  79 static struct buffer_head * ext_find_entry(struct inode * dir,
     /*  */
  80         const char * name, int namelen, struct ext_dir_entry ** res_dir,
  81         struct ext_dir_entry ** prev_dir, struct ext_dir_entry ** next_dir)
  82 {
  83         long offset;
  84         struct buffer_head * bh;
  85         struct ext_dir_entry * de;
  86 
  87         *res_dir = NULL;
  88         if (!dir)
  89                 return NULL;
  90 #ifdef NO_TRUNCATE
  91         if (namelen > EXT_NAME_LEN)
  92                 return NULL;
  93 #else
  94         if (namelen > EXT_NAME_LEN)
  95                 namelen = EXT_NAME_LEN;
  96 #endif
  97         bh = ext_bread(dir,0,0);
  98         if (!bh)
  99                 return NULL;
 100         if (prev_dir)
 101                 *prev_dir = NULL;
 102         if (next_dir)
 103                 *next_dir = NULL;
 104         offset = 0;
 105         de = (struct ext_dir_entry *) bh->b_data;
 106         while (offset < dir->i_size) {
 107                 if ((char *)de >= BLOCK_SIZE+bh->b_data) {
 108                         brelse(bh);
 109                         bh = NULL;
 110                         bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,0);
 111                         if (!bh)
 112                                 continue;
 113                         de = (struct ext_dir_entry *) bh->b_data;
 114                         if (prev_dir)
 115                                 *prev_dir = NULL;
 116                 }
 117                 if (de->rec_len < 8 || de->rec_len % 8 != 0 ||
 118                     de->rec_len < de->name_len + 8 ||
 119                     (((char *) de) + de->rec_len-1 >= BLOCK_SIZE+bh->b_data)) {
 120                         printk ("ext_find_entry: bad dir entry\n");
 121                         printk ("dev=%s, dir=%ld, offset=%ld, "
 122                                 "rec_len=%d, name_len=%d\n",
 123                                 kdevname(dir->i_dev), dir->i_ino, offset,
 124                                 de->rec_len, de->name_len);
 125                         de = (struct ext_dir_entry *) (bh->b_data+BLOCK_SIZE);
 126                         offset = ((offset / BLOCK_SIZE) + 1) * BLOCK_SIZE;
 127                         continue;
 128 /*                      brelse (bh);
 129                         return NULL; */
 130                 }
 131                 if (ext_match(namelen,name,de)) {
 132                         *res_dir = de;
 133                         if (next_dir)
 134                                 if (offset + de->rec_len < dir->i_size &&
 135                                     ((char *)de) + de->rec_len < BLOCK_SIZE+bh->b_data)
 136                                         *next_dir = (struct ext_dir_entry *)
 137                                                 ((char *) de + de->rec_len);
 138                                 else
 139                                         *next_dir = NULL;
 140                         return bh;
 141                 }
 142                 offset += de->rec_len;
 143                 if (prev_dir)
 144                         *prev_dir = de;
 145                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 146         }
 147         brelse(bh);
 148         return NULL;
 149 }
 150 
 151 int ext_lookup(struct inode * dir,const char * name, int len,
     /*  */
 152         struct inode ** result)
 153 {
 154         int ino;
 155         struct ext_dir_entry * de;
 156         struct buffer_head * bh;
 157 
 158         *result = NULL;
 159         if (!dir)
 160                 return -ENOENT;
 161         if (!S_ISDIR(dir->i_mode)) {
 162                 iput(dir);
 163                 return -ENOENT;
 164         }
 165         if (!(bh = ext_find_entry(dir,name,len,&de,NULL,NULL))) {
 166                 iput(dir);
 167                 return -ENOENT;
 168         }
 169         ino = de->inode;
 170         brelse(bh);
 171         if (!(*result = iget(dir->i_sb,ino))) {
 172                 iput(dir);
 173                 return -EACCES;
 174         }
 175         iput(dir);
 176         return 0;
 177 }
 178 
 179 /*
 180  *      ext_add_entry()
 181  *
 182  * adds a file entry to the specified directory, using the same
 183  * semantics as ext_find_entry(). It returns NULL if it failed.
 184  *
 185  * NOTE!! The inode part of 'de' is left at 0 - which means you
 186  * may not sleep between calling this and putting something into
 187  * the entry, as someone else might have used it while you slept.
 188  */
 189 static struct buffer_head * ext_add_entry(struct inode * dir,
     /*  */
 190         const char * name, int namelen, struct ext_dir_entry ** res_dir)
 191 {
 192         int i;
 193         long offset;
 194         unsigned short rec_len;
 195         struct buffer_head * bh;
 196         struct ext_dir_entry * de, * de1;
 197 
 198         *res_dir = NULL;
 199         if (!dir)
 200                 return NULL;
 201 #ifdef NO_TRUNCATE
 202         if (namelen > EXT_NAME_LEN)
 203                 return NULL;
 204 #else
 205         if (namelen > EXT_NAME_LEN)
 206                 namelen = EXT_NAME_LEN;
 207 #endif
 208         if (!namelen)
 209                 return NULL;
 210         bh = ext_bread(dir,0,0);
 211         if (!bh)
 212                 return NULL;
 213         rec_len = ((8 + namelen + EXT_DIR_PAD - 1) / EXT_DIR_PAD) * EXT_DIR_PAD;
 214         offset = 0;
 215         de = (struct ext_dir_entry *) bh->b_data;
 216         while (1) {
 217                 if ((char *)de >= BLOCK_SIZE+bh->b_data && offset < dir->i_size) {
 218 #ifdef EXTFS_DEBUG
 219 printk ("ext_add_entry: skipping to next block\n");
 220 #endif
 221                         brelse(bh);
 222                         bh = NULL;
 223                         bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,0);
 224                         if (!bh)
 225                                 return NULL;
 226                         de = (struct ext_dir_entry *) bh->b_data;
 227                 }
 228                 if (offset >= dir->i_size) {
 229                         /* Check that the directory entry fits in the block */
 230                         if (offset % BLOCK_SIZE == 0  ||
 231                             (BLOCK_SIZE - (offset % BLOCK_SIZE)) < rec_len) {
 232                                 if ((offset % BLOCK_SIZE) != 0) {
 233                                         /* If the entry does not fit in the
 234                                            block, the remainder of the block
 235                                            becomes an unused entry */
 236                                         de->inode = 0;
 237                                         de->rec_len = BLOCK_SIZE
 238                                                 - (offset & (BLOCK_SIZE - 1));
 239                                         de->name_len = 0;
 240                                         offset += de->rec_len;
 241                                         dir->i_size += de->rec_len;
 242                                         dir->i_dirt = 1;
 243 #if 0
 244                                         dir->i_ctime = CURRENT_TIME;
 245 #endif
 246                                         mark_buffer_dirty(bh, 1);
 247                                 }
 248                                 brelse (bh);
 249                                 bh = NULL;
 250 #ifdef EXTFS_DEBUG
 251 printk ("ext_add_entry : creating next block\n");
 252 #endif
 253                                 bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,1);
 254                                 if (!bh)
 255                                         return NULL; /* Other thing to do ??? */
 256                                 de = (struct ext_dir_entry *) bh->b_data;
 257                         }
 258                         /* Allocate the entry */
 259                         de->inode=0;
 260                         de->rec_len = rec_len;
 261                         dir->i_size += de->rec_len;
 262                         dir->i_dirt = 1;
 263 #if 0
 264                         dir->i_ctime = CURRENT_TIME;
 265 #endif
 266                 }
 267                 if (de->rec_len < 8 || de->rec_len % 4 != 0 ||
 268                     de->rec_len < de->name_len + 8 ||
 269                     (((char *) de) + de->rec_len-1 >= BLOCK_SIZE+bh->b_data)) {
 270                         printk ("ext_addr_entry: bad dir entry\n");
 271                         printk ("dev=%s, dir=%ld, offset=%ld, "
 272                                 "rec_len=%d, name_len=%d\n",
 273                                 kdevname(dir->i_dev), dir->i_ino, offset,
 274                                 de->rec_len, de->name_len);
 275                         brelse (bh);
 276                         return NULL;
 277                 }
 278                 if (!de->inode && de->rec_len >= rec_len) {
 279                         if (de->rec_len > rec_len
 280                             && de->rec_len - rec_len >= EXT_DIR_MIN_SIZE) {
 281                                 /* The found entry is too big : it is split
 282                                    into 2 ones :
 283                                    - the 1st one will be used to hold the name,
 284                                    - the 2nd one is unused */
 285                                 de1 = (struct ext_dir_entry *) ((char *) de + rec_len);
 286                                 de1->inode = 0;
 287                                 de1->rec_len = de->rec_len - rec_len;
 288                                 de1->name_len = 0;
 289                                 de->rec_len = rec_len;
 290                         }
 291                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 292                         dir->i_dirt = 1;
 293                         de->name_len = namelen;
 294                         for (i=0; i < namelen ; i++)
 295                                 de->name[i] = name[i];
 296                         mark_buffer_dirty(bh, 1);
 297                         *res_dir = de;
 298                         return bh;
 299                 }
 300                 offset += de->rec_len;
 301                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 302         }
 303         brelse(bh);
 304         return NULL;
 305 }
 306 
 307 int ext_create(struct inode * dir,const char * name, int len, int mode,
     /*  */
 308         struct inode ** result)
 309 {
 310         struct inode * inode;
 311         struct buffer_head * bh;
 312         struct ext_dir_entry * de;
 313 
 314         *result = NULL;
 315         if (!dir)
 316                 return -ENOENT;
 317         inode = ext_new_inode(dir);
 318         if (!inode) {
 319                 iput(dir);
 320                 return -ENOSPC;
 321         }
 322         inode->i_op = &ext_file_inode_operations;
 323         inode->i_mode = mode;
 324         inode->i_dirt = 1;
 325         bh = ext_add_entry(dir,name,len,&de);
 326         if (!bh) {
 327                 inode->i_nlink--;
 328                 inode->i_dirt = 1;
 329                 iput(inode);
 330                 iput(dir);
 331                 return -ENOSPC;
 332         }
 333         de->inode = inode->i_ino;
 334         mark_buffer_dirty(bh, 1);
 335         brelse(bh);
 336         iput(dir);
 337         *result = inode;
 338         return 0;
 339 }
 340 
 341 int ext_mknod(struct inode * dir, const char * name, int len, int mode, int rdev)
     /*  */
 342 {
 343         struct inode * inode;
 344         struct buffer_head * bh;
 345         struct ext_dir_entry * de;
 346 
 347         if (!dir)
 348                 return -ENOENT;
 349         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 350         if (bh) {
 351                 brelse(bh);
 352                 iput(dir);
 353                 return -EEXIST;
 354         }
 355         inode = ext_new_inode(dir);
 356         if (!inode) {
 357                 iput(dir);
 358                 return -ENOSPC;
 359         }
 360         inode->i_uid = current->fsuid;
 361         inode->i_mode = mode;
 362         inode->i_op = NULL;
 363         if (S_ISREG(inode->i_mode))
 364                 inode->i_op = &ext_file_inode_operations;
 365         else if (S_ISDIR(inode->i_mode)) {
 366                 inode->i_op = &ext_dir_inode_operations;
 367                 if (dir->i_mode & S_ISGID)
 368                         inode->i_mode |= S_ISGID;
 369         }
 370         else if (S_ISLNK(inode->i_mode))
 371                 inode->i_op = &ext_symlink_inode_operations;
 372         else if (S_ISCHR(inode->i_mode))
 373                 inode->i_op = &chrdev_inode_operations;
 374         else if (S_ISBLK(inode->i_mode))
 375                 inode->i_op = &blkdev_inode_operations;
 376         else if (S_ISFIFO(inode->i_mode))
 377                 init_fifo(inode);
 378         if (S_ISBLK(mode) || S_ISCHR(mode))
 379                 inode->i_rdev = to_kdev_t(rdev);
 380 #if 0
 381         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 382 #endif
 383         inode->i_dirt = 1;
 384         bh = ext_add_entry(dir,name,len,&de);
 385         if (!bh) {
 386                 inode->i_nlink--;
 387                 inode->i_dirt = 1;
 388                 iput(inode);
 389                 iput(dir);
 390                 return -ENOSPC;
 391         }
 392         de->inode = inode->i_ino;
 393         mark_buffer_dirty(bh, 1);
 394         brelse(bh);
 395         iput(dir);
 396         iput(inode);
 397         return 0;
 398 }
 399 
 400 int ext_mkdir(struct inode * dir, const char * name, int len, int mode)
     /*  */
 401 {
 402         struct inode * inode;
 403         struct buffer_head * bh, *dir_block;
 404         struct ext_dir_entry * de;
 405         
 406         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 407         if (bh) {
 408                 brelse(bh);
 409                 iput(dir);
 410                 return -EEXIST;
 411         }
 412         inode = ext_new_inode(dir);
 413         if (!inode) {
 414                 iput(dir);
 415                 return -ENOSPC;
 416         }
 417         inode->i_op = &ext_dir_inode_operations;
 418         inode->i_size = 2 * 16; /* Each entry is coded on 16 bytes for "." and ".."
 419                                         - 4 bytes for the inode number,
 420                                         - 2 bytes for the record length
 421                                         - 2 bytes for the name length
 422                                         - 8 bytes for the name */
 423 #if 0
 424         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 425 #endif
 426         dir_block = ext_bread(inode,0,1);
 427         if (!dir_block) {
 428                 iput(dir);
 429                 inode->i_nlink--;
 430                 inode->i_dirt = 1;
 431                 iput(inode);
 432                 return -ENOSPC;
 433         }
 434         de = (struct ext_dir_entry *) dir_block->b_data;
 435         de->inode=inode->i_ino;
 436         de->rec_len=16;
 437         de->name_len=1;
 438         strcpy(de->name,".");
 439         de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 440         de->inode = dir->i_ino;
 441         de->rec_len=16;
 442         de->name_len=2;
 443         strcpy(de->name,"..");
 444         inode->i_nlink = 2;
 445         mark_buffer_dirty(dir_block, 1);
 446         brelse(dir_block);
 447         inode->i_mode = S_IFDIR | (mode & 0777 & ~current->fs->umask);
 448         if (dir->i_mode & S_ISGID)
 449                 inode->i_mode |= S_ISGID;
 450         inode->i_dirt = 1;
 451         bh = ext_add_entry(dir,name,len,&de);
 452         if (!bh) {
 453                 iput(dir);
 454                 inode->i_nlink=0;
 455                 iput(inode);
 456                 return -ENOSPC;
 457         }
 458         de->inode = inode->i_ino;
 459         mark_buffer_dirty(bh, 1);
 460         dir->i_nlink++;
 461         dir->i_dirt = 1;
 462         iput(dir);
 463         iput(inode);
 464         brelse(bh);
 465         return 0;
 466 }
 467 
 468 /*
 469  * routine to check that the specified directory is empty (for rmdir)
 470  */
 471 static int empty_dir(struct inode * inode)
     /*  */
 472 {
 473         unsigned long offset;
 474         struct buffer_head * bh;
 475         struct ext_dir_entry * de, * de1;
 476 
 477         if (inode->i_size < 2 * 12 || !(bh = ext_bread(inode,0,0))) {
 478                 printk("warning - bad directory on dev %s\n",
 479                        kdevname(inode->i_dev));
 480                 return 1;
 481         }
 482         de = (struct ext_dir_entry *) bh->b_data;
 483         de1 = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 484         if (de->inode != inode->i_ino || !de1->inode || 
 485             strcmp(".",de->name) || strcmp("..",de1->name)) {
 486                 printk("warning - bad directory on dev %s\n",
 487                        kdevname(inode->i_dev));
 488                 return 1;
 489         }
 490         offset = de->rec_len + de1->rec_len;
 491         de = (struct ext_dir_entry *) ((char *) de1 + de1->rec_len);
 492         while (offset < inode->i_size ) {
 493                 if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) {
 494                         brelse(bh);
 495                         bh = ext_bread(inode, offset >> BLOCK_SIZE_BITS,1);
 496                         if (!bh) {
 497                                 offset += BLOCK_SIZE;
 498                                 continue;
 499                         }
 500                         de = (struct ext_dir_entry *) bh->b_data;
 501                 }
 502                 if (de->rec_len < 8 || de->rec_len %4 != 0 ||
 503                     de->rec_len < de->name_len + 8) {
 504                         printk ("empty_dir: bad dir entry\n");
 505                         printk ("dev=%s, dir=%ld, offset=%ld, "
 506                                 "rec_len=%d, name_len=%d\n",
 507                                 kdevname(inode->i_dev), inode->i_ino,
 508                                 offset, de->rec_len, de->name_len);
 509                         brelse (bh);
 510                         return 1;
 511                 }
 512                 if (de->inode) {
 513                         brelse(bh);
 514                         return 0;
 515                 }
 516                 offset += de->rec_len;
 517                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 518         }
 519         brelse(bh);
 520         return 1;
 521 }
 522 
 523 static inline void ext_merge_entries (struct ext_dir_entry * de,
     /*  */
 524         struct ext_dir_entry * pde, struct ext_dir_entry * nde)
 525 {
 526         if (nde && !nde->inode)
 527                 de->rec_len += nde->rec_len;
 528         if (pde && !pde->inode)
 529                 pde->rec_len += de->rec_len;
 530 }
 531 
 532 int ext_rmdir(struct inode * dir, const char * name, int len)
     /*  */
 533 {
 534         int retval;
 535         struct inode * inode;
 536         struct buffer_head * bh;
 537         struct ext_dir_entry * de, * pde, * nde;
 538 
 539         inode = NULL;
 540         bh = ext_find_entry(dir,name,len,&de,&pde,&nde);
 541         retval = -ENOENT;
 542         if (!bh)
 543                 goto end_rmdir;
 544         retval = -EPERM;
 545         if (!(inode = iget(dir->i_sb, de->inode)))
 546                 goto end_rmdir;
 547         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 548             current->fsuid != inode->i_uid &&
 549             current->fsuid != dir->i_uid)
 550                 goto end_rmdir;
 551         if (inode->i_dev != dir->i_dev)
 552                 goto end_rmdir;
 553         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 554                 goto end_rmdir;
 555         if (!S_ISDIR(inode->i_mode)) {
 556                 retval = -ENOTDIR;
 557                 goto end_rmdir;
 558         }
 559         if (!empty_dir(inode)) {
 560                 retval = -ENOTEMPTY;
 561                 goto end_rmdir;
 562         }
 563         if (inode->i_count > 1) {
 564                 retval = -EBUSY;
 565                 goto end_rmdir;
 566         }
 567         if (inode->i_nlink != 2)
 568                 printk("empty directory has nlink!=2 (%d)\n",inode->i_nlink);
 569         de->inode = 0;
 570         de->name_len = 0;
 571         ext_merge_entries (de, pde, nde);
 572         mark_buffer_dirty(bh, 1);
 573         inode->i_nlink=0;
 574         inode->i_dirt=1;
 575         dir->i_nlink--;
 576         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 577         dir->i_dirt=1;
 578         retval = 0;
 579 end_rmdir:
 580         iput(dir);
 581         iput(inode);
 582         brelse(bh);
 583         return retval;
 584 }
 585 
 586 int ext_unlink(struct inode * dir, const char * name, int len)
     /*  */
 587 {
 588         int retval;
 589         struct inode * inode;
 590         struct buffer_head * bh;
 591         struct ext_dir_entry * de, * pde, * nde;
 592 
 593         retval = -ENOENT;
 594         inode = NULL;
 595         bh = ext_find_entry(dir,name,len,&de,&pde,&nde);
 596         if (!bh)
 597                 goto end_unlink;
 598         if (!(inode = iget(dir->i_sb, de->inode)))
 599                 goto end_unlink;
 600         retval = -EPERM;
 601         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 602             current->fsuid != inode->i_uid &&
 603             current->fsuid != dir->i_uid)
 604                 goto end_unlink;
 605         if (S_ISDIR(inode->i_mode))
 606                 goto end_unlink;
 607         if (!inode->i_nlink) {
 608                 printk("Deleting nonexistent file (%s:%ld), %d\n",
 609                        kdevname(inode->i_dev), inode->i_ino,
 610                        inode->i_nlink);
 611                 inode->i_nlink=1;
 612         }
 613         de->inode = 0;
 614         de->name_len = 0;
 615         ext_merge_entries (de, pde, nde);
 616         mark_buffer_dirty(bh, 1);
 617         inode->i_nlink--;
 618         inode->i_dirt = 1;
 619         inode->i_ctime = CURRENT_TIME;
 620         dir->i_ctime = dir->i_mtime = inode->i_ctime;
 621         dir->i_dirt = 1;
 622         retval = 0;
 623 end_unlink:
 624         brelse(bh);
 625         iput(inode);
 626         iput(dir);
 627         return retval;
 628 }
 629 
 630 int ext_symlink(struct inode * dir, const char * name, int len, const char * symname)
     /*  */
 631 {
 632         struct ext_dir_entry * de;
 633         struct inode * inode = NULL;
 634         struct buffer_head * bh = NULL, * name_block = NULL;
 635         int i;
 636         char c;
 637 
 638         if (!(inode = ext_new_inode(dir))) {
 639                 iput(dir);
 640                 return -ENOSPC;
 641         }
 642         inode->i_mode = S_IFLNK | 0777;
 643         inode->i_op = &ext_symlink_inode_operations;
 644         name_block = ext_bread(inode,0,1);
 645         if (!name_block) {
 646                 iput(dir);
 647                 inode->i_nlink--;
 648                 inode->i_dirt = 1;
 649                 iput(inode);
 650                 return -ENOSPC;
 651         }
 652         i = 0;
 653         while (i < 1023 && (c = *(symname++)))
 654                 name_block->b_data[i++] = c;
 655         name_block->b_data[i] = 0;
 656         mark_buffer_dirty(name_block, 1);
 657         brelse(name_block);
 658         inode->i_size = i;
 659         inode->i_dirt = 1;
 660         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 661         if (bh) {
 662                 inode->i_nlink--;
 663                 inode->i_dirt = 1;
 664                 iput(inode);
 665                 brelse(bh);
 666                 iput(dir);
 667                 return -EEXIST;
 668         }
 669         bh = ext_add_entry(dir,name,len,&de);
 670         if (!bh) {
 671                 inode->i_nlink--;
 672                 inode->i_dirt = 1;
 673                 iput(inode);
 674                 iput(dir);
 675                 return -ENOSPC;
 676         }
 677         de->inode = inode->i_ino;
 678         mark_buffer_dirty(bh, 1);
 679         brelse(bh);
 680         iput(dir);
 681         iput(inode);
 682         return 0;
 683 }
 684 
 685 int ext_link(struct inode * oldinode, struct inode * dir, const char * name, int len)
     /*  */
 686 {
 687         struct ext_dir_entry * de;
 688         struct buffer_head * bh;
 689 
 690         if (S_ISDIR(oldinode->i_mode)) {
 691                 iput(oldinode);
 692                 iput(dir);
 693                 return -EPERM;
 694         }
 695         if (oldinode->i_nlink > 32000) {
 696                 iput(oldinode);
 697                 iput(dir);
 698                 return -EMLINK;
 699         }
 700         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 701         if (bh) {
 702                 brelse(bh);
 703                 iput(dir);
 704                 iput(oldinode);
 705                 return -EEXIST;
 706         }
 707         bh = ext_add_entry(dir,name,len,&de);
 708         if (!bh) {
 709                 iput(dir);
 710                 iput(oldinode);
 711                 return -ENOSPC;
 712         }
 713         de->inode = oldinode->i_ino;
 714         mark_buffer_dirty(bh, 1);
 715         brelse(bh);
 716         iput(dir);
 717         oldinode->i_nlink++;
 718         oldinode->i_ctime = CURRENT_TIME;
 719         oldinode->i_dirt = 1;
 720         iput(oldinode);
 721         return 0;
 722 }
 723 
 724 static int subdir(struct inode * new_inode, struct inode * old_inode)
     /*  */
 725 {
 726         int ino;
 727         int result;
 728 
 729         new_inode->i_count++;
 730         result = 0;
 731         for (;;) {
 732                 if (new_inode == old_inode) {
 733                         result = 1;
 734                         break;
 735                 }
 736                 if (new_inode->i_dev != old_inode->i_dev)
 737                         break;
 738                 ino = new_inode->i_ino;
 739                 if (ext_lookup(new_inode,"..",2,&new_inode))
 740                         break;
 741                 if (new_inode->i_ino == ino)
 742                         break;
 743         }
 744         iput(new_inode);
 745         return result;
 746 }
 747 
 748 #define PARENT_INO(buffer) \
 749 ((struct ext_dir_entry *) ((char *) buffer + \
 750 ((struct ext_dir_entry *) buffer)->rec_len))->inode
 751 
 752 #define PARENT_NAME(buffer) \
 753 ((struct ext_dir_entry *) ((char *) buffer + \
 754 ((struct ext_dir_entry *) buffer)->rec_len))->name
 755 
 756 /*
 757  * rename uses retrying to avoid race-conditions: at least they should be minimal.
 758  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 759  * checks fail, it tries to restart itself again. Very practical - no changes
 760  * are done until we know everything works ok.. and then all the changes can be
 761  * done in one fell swoop when we have claimed all the buffers needed.
 762  *
 763  * Anybody can rename anything with this: the permission checks are left to the
 764  * higher-level routines.
 765  */
 766 static int do_ext_rename(struct inode * old_dir, const char * old_name, int old_len,
     /*  */
 767         struct inode * new_dir, const char * new_name, int new_len)
 768 {
 769         struct inode * old_inode, * new_inode;
 770         struct buffer_head * old_bh, * new_bh, * dir_bh;
 771         struct ext_dir_entry * old_de, * new_de, * pde, * nde;
 772         int retval;
 773 
 774         goto start_up;
 775 try_again:
 776         brelse(old_bh);
 777         brelse(new_bh);
 778         brelse(dir_bh);
 779         iput(old_inode);
 780         iput(new_inode);
 781         current->counter = 0;
 782         schedule();
 783 start_up:
 784         old_inode = new_inode = NULL;
 785         old_bh = new_bh = dir_bh = NULL;
 786         old_bh = ext_find_entry(old_dir,old_name,old_len,&old_de,&pde,&nde);
 787         retval = -ENOENT;
 788         if (!old_bh)
 789                 goto end_rename;
 790         old_inode = __iget(old_dir->i_sb, old_de->inode,0); /* don't cross mnt-points */
 791         if (!old_inode)
 792                 goto end_rename;
 793         retval = -EPERM;
 794         if ((old_dir->i_mode & S_ISVTX) && 
 795             current->fsuid != old_inode->i_uid &&
 796             current->fsuid != old_dir->i_uid && !fsuser())
 797                 goto end_rename;
 798         new_bh = ext_find_entry(new_dir,new_name,new_len,&new_de,NULL,NULL);
 799         if (new_bh) {
 800                 new_inode = __iget(new_dir->i_sb, new_de->inode,0); /* don't cross mnt-points */
 801                 if (!new_inode) {
 802                         brelse(new_bh);
 803                         new_bh = NULL;
 804                 }
 805         }
 806         if (new_inode == old_inode) {
 807                 retval = 0;
 808                 goto end_rename;
 809         }
 810         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 811                 retval = -EEXIST;
 812                 goto end_rename;
 813         }
 814         retval = -EPERM;
 815         if (new_inode && (new_dir->i_mode & S_ISVTX) && 
 816             current->fsuid != new_inode->i_uid &&
 817             current->fsuid != new_dir->i_uid && !fsuser())
 818                 goto end_rename;
 819         if (S_ISDIR(old_inode->i_mode)) {
 820                 retval = -EEXIST;
 821                 if (new_bh)
 822                         goto end_rename;
 823                 if ((retval = permission(old_inode, MAY_WRITE)) != 0)
 824                         goto end_rename;
 825                 retval = -EINVAL;
 826                 if (subdir(new_dir, old_inode))
 827                         goto end_rename;
 828                 retval = -EIO;
 829                 dir_bh = ext_bread(old_inode,0,0);
 830                 if (!dir_bh)
 831                         goto end_rename;
 832                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 833                         goto end_rename;
 834         }
 835         if (!new_bh)
 836                 new_bh = ext_add_entry(new_dir,new_name,new_len,&new_de);
 837         retval = -ENOSPC;
 838         if (!new_bh)
 839                 goto end_rename;
 840 /* sanity checking before doing the rename - avoid races */
 841         if (new_inode && (new_de->inode != new_inode->i_ino))
 842                 goto try_again;
 843         if (new_de->inode && !new_inode)
 844                 goto try_again;
 845         if (old_de->inode != old_inode->i_ino)
 846                 goto try_again;
 847 /* ok, that's it */
 848         old_de->inode = 0;
 849         old_de->name_len = 0;
 850         new_de->inode = old_inode->i_ino;
 851         ext_merge_entries (old_de, pde, nde);
 852         if (new_inode) {
 853                 new_inode->i_nlink--;
 854                 new_inode->i_dirt = 1;
 855         }
 856         mark_buffer_dirty(old_bh, 1);
 857         mark_buffer_dirty(new_bh, 1);
 858         if (dir_bh) {
 859                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
 860                 mark_buffer_dirty(dir_bh, 1);
 861                 old_dir->i_nlink--;
 862                 new_dir->i_nlink++;
 863                 old_dir->i_dirt = 1;
 864                 new_dir->i_dirt = 1;
 865         }
 866         retval = 0;
 867 end_rename:
 868         brelse(dir_bh);
 869         brelse(old_bh);
 870         brelse(new_bh);
 871         iput(old_inode);
 872         iput(new_inode);
 873         iput(old_dir);
 874         iput(new_dir);
 875         return retval;
 876 }
 877 
 878 /*
 879  * Ok, rename also locks out other renames, as they can change the parent of
 880  * a directory, and we don't want any races. Other races are checked for by
 881  * "do_rename()", which restarts if there are inconsistencies.
 882  *
 883  * Note that there is no race between different filesystems: it's only within
 884  * the same device that races occur: many renames can happen at once, as long
 885  * as they are on different partitions.
 886  */
 887 int ext_rename(struct inode * old_dir, const char * old_name, int old_len,
     /*  */
 888         struct inode * new_dir, const char * new_name, int new_len)
 889 {
 890         static struct wait_queue * wait = NULL;
 891         static int lock = 0;
 892         int result;
 893 
 894         while (lock)
 895                 sleep_on(&wait);
 896         lock = 1;
 897         result = do_ext_rename(old_dir, old_name, old_len,
 898                 new_dir, new_name, new_len);
 899         lock = 0;
 900         wake_up(&wait);
 901         return result;
 902 }

/* */