fs/hostfs/hostfs_kern.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  *
   5  * Ported the filesystem routines to 2.5.
   6  * 2003-02-10 Petr Baudis <pasky@ucw.cz>
   7  */
   8
   9 #include <linux/stddef.h>
  10 #include <linux/fs.h>
  11 #include <linux/version.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/slab.h>
  15 #include <linux/pagemap.h>
  16 #include <linux/blkdev.h>
  17 #include <linux/list.h>
  18 #include <linux/statfs.h>
  19 #include <linux/kdev_t.h>
  20 #include <asm/uaccess.h>
  21 #include "hostfs.h"
  22 #include "kern_util.h"
  23 #include "kern.h"
  24 #include "user_util.h"
  25 #include "init.h"
  26
  27 struct hostfs_inode_info {
  28         char *host_filename;
  29         int fd;
  30         int mode;
  31         struct inode vfs_inode;
  32 };
  33
  34 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
  35 {
  36         return(list_entry(inode, struct hostfs_inode_info, vfs_inode));
  37 }
  38
  39 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_dentry->d_inode)
  40
  41 int hostfs_d_delete(struct dentry *dentry)
  42 {
  43         return(1);
  44 }
  45
  46 struct dentry_operations hostfs_dentry_ops = {
  47         .d_delete               = hostfs_d_delete,
  48 };
  49
  50 /* Changed in hostfs_args before the kernel starts running */
  51 static char *root_ino = "/";
  52 static int append = 0;
  53
  54 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
  55
  56 static struct inode_operations hostfs_iops;
  57 static struct inode_operations hostfs_dir_iops;
  58 static struct address_space_operations hostfs_link_aops;
  59
  60 #ifndef MODULE
  61 static int __init hostfs_args(char *options, int *add)
  62 {
  63         char *ptr;
  64
  65         ptr = strchr(options, ',');
  66         if(ptr != NULL)
  67                 *ptr++ = '\0';
  68         if(*options != '\0')
  69                 root_ino = options;
  70
  71         options = ptr;
  72         while(options){
  73                 ptr = strchr(options, ',');
  74                 if(ptr != NULL)
  75                         *ptr++ = '\0';
  76                 if(*options != '\0'){
  77                         if(!strcmp(options, "append"))
  78                                 append = 1;
  79                         else printf("hostfs_args - unsupported option - %s\n",
  80                                     options);
  81                 }
  82                 options = ptr;
  83         }
  84         return(0);
  85 }
  86
  87 __uml_setup("hostfs=", hostfs_args,
  88 "hostfs=<root dir>,<flags>,...\n"
  89 "    This is used to set hostfs parameters.  The root directory argument\n"
  90 "    is used to confine all hostfs mounts to within the specified directory\n"
  91 "    tree on the host.  If this isn't specified, then a user inside UML can\n"
  92 "    mount anything on the host that's accessible to the user that's running\n"
  93 "    it.\n"
  94 "    The only flag currently supported is 'append', which specifies that all\n"
  95 "    files opened by hostfs will be opened in append mode.\n\n"
  96 );
  97 #endif
  98
  99 static char *dentry_name(struct dentry *dentry, int extra)
 100 {
 101         struct dentry *parent;
 102         char *root, *name;
 103         int len;
 104
 105         len = 0;
 106         parent = dentry;
 107         while(parent->d_parent != parent){
 108                 len += parent->d_name.len + 1;
 109                 parent = parent->d_parent;
 110         }
 111
 112         root = HOSTFS_I(parent->d_inode)->host_filename;
 113         len += strlen(root);
 114         name = kmalloc(len + extra + 1, GFP_KERNEL);
 115         if(name == NULL) return(NULL);
 116
 117         name[len] = '\0';
 118         parent = dentry;
 119         while(parent->d_parent != parent){
 120                 len -= parent->d_name.len + 1;
 121                 name[len] = '/';
 122                 strncpy(&name[len + 1], parent->d_name.name,
 123                         parent->d_name.len);
 124                 parent = parent->d_parent;
 125         }
 126         strncpy(name, root, strlen(root));
 127         return(name);
 128 }
 129
 130 static char *inode_name(struct inode *ino, int extra)
 131 {
 132         struct dentry *dentry;
 133
 134         dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
 135         return(dentry_name(dentry, extra));
 136 }
 137
 138 static int read_name(struct inode *ino, char *name)
 139 {
 140         /* The non-int inode fields are copied into ints by stat_file and
 141          * then copied into the inode because passing the actual pointers
 142          * in and having them treated as int * breaks on big-endian machines
 143          */
 144         int err;
 145         int i_mode, i_nlink, i_blksize;
 146         unsigned long long i_size;
 147         unsigned long long i_ino;
 148         unsigned long long i_blocks;
 149
 150         err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
 151                         &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
 152                         &ino->i_ctime, &i_blksize, &i_blocks);
 153         if(err)
 154                 return(err);
 155
 156         ino->i_ino = i_ino;
 157         ino->i_mode = i_mode;
 158         ino->i_nlink = i_nlink;
 159         ino->i_size = i_size;
 160         ino->i_blksize = i_blksize;
 161         ino->i_blocks = i_blocks;
 162         return(0);
 163 }
 164
 165 static char *follow_link(char *link)
 166 {
 167         int len, n;
 168         char *name, *resolved, *end;
 169
 170         len = 64;
 171         while(1){
 172                 n = -ENOMEM;
 173                 name = kmalloc(len, GFP_KERNEL);
 174                 if(name == NULL)
 175                         goto out;
 176
 177                 n = do_readlink(link, name, len);
 178                 if(n < len)
 179                         break;
 180                 len *= 2;
 181                 kfree(name);
 182         }
 183         if(n < 0)
 184                 goto out_free;
 185
 186         if(*name == '/')
 187                 return(name);
 188
 189         end = strrchr(link, '/');
 190         if(end == NULL)
 191                 return(name);
 192
 193         *(end + 1) = '\0';
 194         len = strlen(link) + strlen(name) + 1;
 195
 196         resolved = kmalloc(len, GFP_KERNEL);
 197         if(resolved == NULL){
 198                 n = -ENOMEM;
 199                 goto out_free;
 200         }
 201
 202         sprintf(resolved, "%s%s", link, name);
 203         kfree(name);
 204         kfree(link);
 205         return(resolved);
 206
 207  out_free:
 208         kfree(name);
 209  out:
 210         return(ERR_PTR(n));
 211 }
 212
 213 static int read_inode(struct inode *ino)
 214 {
 215         char *name;
 216         int err = 0;
 217
 218         /* Unfortunately, we are called from iget() when we don't have a dentry
 219          * allocated yet.
 220          */
 221         if(list_empty(&ino->i_dentry))
 222                 goto out;
 223
 224         err = -ENOMEM;
 225         name = inode_name(ino, 0);
 226         if(name == NULL)
 227                 goto out;
 228
 229         if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){
 230                 name = follow_link(name);
 231                 if(IS_ERR(name)){
 232                         err = PTR_ERR(name);
 233                         goto out;
 234                 }
 235         }
 236
 237         err = read_name(ino, name);
 238         kfree(name);
 239  out:
 240         return(err);
 241 }
 242
 243 int hostfs_statfs(struct super_block *sb, struct kstatfs *sf)
 244 {
 245         /* do_statfs uses struct statfs64 internally, but the linux kernel
 246          * struct statfs still has 32-bit versions for most of these fields,
 247          * so we convert them here
 248          */
 249         int err;
 250         long long f_blocks;
 251         long long f_bfree;
 252         long long f_bavail;
 253         long long f_files;
 254         long long f_ffree;
 255
 256         err = do_statfs(HOSTFS_I(sb->s_root->d_inode)->host_filename,
 257                         &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
 258                         &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
 259                         &sf->f_namelen, sf->f_spare);
 260         if(err) return(err);
 261         sf->f_blocks = f_blocks;
 262         sf->f_bfree = f_bfree;
 263         sf->f_bavail = f_bavail;
 264         sf->f_files = f_files;
 265         sf->f_ffree = f_ffree;
 266         sf->f_type = HOSTFS_SUPER_MAGIC;
 267         return(0);
 268 }
 269
 270 static struct inode *hostfs_alloc_inode(struct super_block *sb)
 271 {
 272         struct hostfs_inode_info *hi;
 273
 274         hi = kmalloc(sizeof(*hi), GFP_KERNEL);
 275         if(hi == NULL)
 276                 return(NULL);
 277
 278         *hi = ((struct hostfs_inode_info) { .host_filename      = NULL,
 279                                             .fd                 = -1,
 280                                             .mode               = 0 });
 281         inode_init_once(&hi->vfs_inode);
 282         return(&hi->vfs_inode);
 283 }
 284
 285 static void hostfs_delete_inode(struct inode *inode)
 286 {
 287         if(HOSTFS_I(inode)->fd != -1) {
 288                 close_file(&HOSTFS_I(inode)->fd);
 289                 HOSTFS_I(inode)->fd = -1;
 290         }
 291         clear_inode(inode);
 292 }
 293
 294 static void hostfs_destroy_inode(struct inode *inode)
 295 {
 296         if(HOSTFS_I(inode)->host_filename)
 297                 kfree(HOSTFS_I(inode)->host_filename);
 298
 299         /*XXX: This should not happen, probably. The check is here for
 300          * additional safety.*/
 301         if(HOSTFS_I(inode)->fd != -1) {
 302                 close_file(&HOSTFS_I(inode)->fd);
 303                 printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
 304         }
 305
 306         kfree(HOSTFS_I(inode));
 307 }
 308
 309 static void hostfs_read_inode(struct inode *inode)
 310 {
 311         read_inode(inode);
 312 }
 313
 314 static struct super_operations hostfs_sbops = {
 315         .alloc_inode    = hostfs_alloc_inode,
 316         .drop_inode     = generic_delete_inode,
 317         .delete_inode   = hostfs_delete_inode,
 318         .destroy_inode  = hostfs_destroy_inode,
 319         .read_inode     = hostfs_read_inode,
 320         .statfs         = hostfs_statfs,
 321 };
 322
 323 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
 324 {
 325         void *dir;
 326         char *name;
 327         unsigned long long next, ino;
 328         int error, len;
 329
 330         name = dentry_name(file->f_dentry, 0);
 331         if(name == NULL) return(-ENOMEM);
 332         dir = open_dir(name, &error);
 333         kfree(name);
 334         if(dir == NULL) return(-error);
 335         next = file->f_pos;
 336         while((name = read_dir(dir, &next, &ino, &len)) != NULL){
 337                 error = (*filldir)(ent, name, len, file->f_pos,
 338                                    ino, DT_UNKNOWN);
 339                 if(error) break;
 340                 file->f_pos = next;
 341         }
 342         close_dir(dir);
 343         return(0);
 344 }
 345
 346 int hostfs_file_open(struct inode *ino, struct file *file)
 347 {
 348         char *name;
 349         int mode = 0, r = 0, w = 0, fd;
 350
 351         mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
 352         if((mode & HOSTFS_I(ino)->mode) == mode)
 353                 return(0);
 354
 355         /* The file may already have been opened, but with the wrong access,
 356          * so this resets things and reopens the file with the new access.
 357          */
 358         if(HOSTFS_I(ino)->fd != -1){
 359                 close_file(&HOSTFS_I(ino)->fd);
 360                 HOSTFS_I(ino)->fd = -1;
 361         }
 362
 363         HOSTFS_I(ino)->mode |= mode;
 364         if(HOSTFS_I(ino)->mode & FMODE_READ)
 365                 r = 1;
 366         if(HOSTFS_I(ino)->mode & FMODE_WRITE)
 367                 w = 1;
 368         if(w)
 369                 r = 1;
 370
 371         name = dentry_name(file->f_dentry, 0);
 372         if(name == NULL)
 373                 return(-ENOMEM);
 374
 375         fd = open_file(name, r, w, append);
 376         kfree(name);
 377         if(fd < 0) return(fd);
 378         FILE_HOSTFS_I(file)->fd = fd;
 379
 380         return(0);
 381 }
 382
 383 int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 384 {
 385         return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync);
 386 }
 387
 388 static struct file_operations hostfs_file_fops = {
 389         .llseek         = generic_file_llseek,
 390         .read           = generic_file_read,
 391         .sendfile       = generic_file_sendfile,
 392         .aio_read       = generic_file_aio_read,
 393         .aio_write      = generic_file_aio_write,
 394         .readv          = generic_file_readv,
 395         .writev         = generic_file_writev,
 396         .write          = generic_file_write,
 397         .mmap           = generic_file_mmap,
 398         .open           = hostfs_file_open,
 399         .release        = NULL,
 400         .fsync          = hostfs_fsync,
 401 };
 402
 403 static struct file_operations hostfs_dir_fops = {
 404         .llseek         = generic_file_llseek,
 405         .readdir        = hostfs_readdir,
 406         .read           = generic_read_dir,
 407 };
 408
 409 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 410 {
 411         struct address_space *mapping = page->mapping;
 412         struct inode *inode = mapping->host;
 413         char *buffer;
 414         unsigned long long base;
 415         int count = PAGE_CACHE_SIZE;
 416         int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
 417         int err;
 418
 419         if (page->index >= end_index)
 420                 count = inode->i_size & (PAGE_CACHE_SIZE-1);
 421
 422         buffer = kmap(page);
 423         base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
 424
 425         err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 426         if(err != count){
 427                 ClearPageUptodate(page);
 428                 goto out;
 429         }
 430
 431         if (base > inode->i_size)
 432                 inode->i_size = base;
 433
 434         if (PageError(page))
 435                 ClearPageError(page);
 436         err = 0;
 437
 438  out:
 439         kunmap(page);
 440
 441         unlock_page(page);
 442         return err;
 443 }
 444
 445 int hostfs_readpage(struct file *file, struct page *page)
 446 {
 447         char *buffer;
 448         long long start;
 449         int err = 0;
 450
 451         start = (long long) page->index << PAGE_CACHE_SHIFT;
 452         buffer = kmap(page);
 453         err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
 454                         PAGE_CACHE_SIZE);
 455         if(err < 0) goto out;
 456
 457         memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
 458
 459         flush_dcache_page(page);
 460         SetPageUptodate(page);
 461         if (PageError(page)) ClearPageError(page);
 462         err = 0;
 463  out:
 464         kunmap(page);
 465         unlock_page(page);
 466         return(err);
 467 }
 468
 469 int hostfs_prepare_write(struct file *file, struct page *page,
 470                          unsigned int from, unsigned int to)
 471 {
 472         char *buffer;
 473         long long start, tmp;
 474         int err;
 475
 476         start = (long long) page->index << PAGE_CACHE_SHIFT;
 477         buffer = kmap(page);
 478         if(from != 0){
 479                 tmp = start;
 480                 err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer,
 481                                 from);
 482                 if(err < 0) goto out;
 483         }
 484         if(to != PAGE_CACHE_SIZE){
 485                 start += to;
 486                 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to,
 487                                 PAGE_CACHE_SIZE - to);
 488                 if(err < 0) goto out;
 489         }
 490         err = 0;
 491  out:
 492         kunmap(page);
 493         return(err);
 494 }
 495
 496 int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
 497                  unsigned to)
 498 {
 499         struct address_space *mapping = page->mapping;
 500         struct inode *inode = mapping->host;
 501         char *buffer;
 502         long long start;
 503         int err = 0;
 504
 505         start = (long long) (page->index << PAGE_CACHE_SHIFT) + from;
 506         buffer = kmap(page);
 507         err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
 508                          to - from);
 509         if(err > 0) err = 0;
 510         if(!err && (start > inode->i_size))
 511                 inode->i_size = start;
 512
 513         kunmap(page);
 514         return(err);
 515 }
 516
 517 static struct address_space_operations hostfs_aops = {
 518         .writepage      = hostfs_writepage,
 519         .readpage       = hostfs_readpage,
 520         .set_page_dirty = __set_page_dirty_nobuffers,
 521         .prepare_write  = hostfs_prepare_write,
 522         .commit_write   = hostfs_commit_write
 523 };
 524
 525 static int init_inode(struct inode *inode, struct dentry *dentry)
 526 {
 527         char *name;
 528         int type, err = -ENOMEM;
 529         int maj, min;
 530         dev_t rdev = 0;
 531
 532         if(dentry){
 533                 name = dentry_name(dentry, 0);
 534                 if(name == NULL)
 535                         goto out;
 536                 type = file_type(name, &maj, &min);
 537                 /*Reencode maj and min with the kernel encoding.*/
 538                 rdev = MKDEV(maj, min);
 539                 kfree(name);
 540         }
 541         else type = OS_TYPE_DIR;
 542
 543         err = 0;
 544         if(type == OS_TYPE_SYMLINK)
 545                 inode->i_op = &page_symlink_inode_operations;
 546         else if(type == OS_TYPE_DIR)
 547                 inode->i_op = &hostfs_dir_iops;
 548         else inode->i_op = &hostfs_iops;
 549
 550         if(type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
 551         else inode->i_fop = &hostfs_file_fops;
 552
 553         if(type == OS_TYPE_SYMLINK)
 554                 inode->i_mapping->a_ops = &hostfs_link_aops;
 555         else inode->i_mapping->a_ops = &hostfs_aops;
 556
 557         switch (type) {
 558         case OS_TYPE_CHARDEV:
 559                 init_special_inode(inode, S_IFCHR, rdev);
 560                 break;
 561         case OS_TYPE_BLOCKDEV:
 562                 init_special_inode(inode, S_IFBLK, rdev);
 563                 break;
 564         case OS_TYPE_FIFO:
 565                 init_special_inode(inode, S_IFIFO, 0);
 566                 break;
 567         case OS_TYPE_SOCK:
 568                 init_special_inode(inode, S_IFSOCK, 0);
 569                 break;
 570         }
 571  out:
 572         return(err);
 573 }
 574
 575 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
 576                  struct nameidata *nd)
 577 {
 578         struct inode *inode;
 579         char *name;
 580         int error, fd;
 581
 582         error = -ENOMEM;
 583         inode = iget(dir->i_sb, 0);
 584         if(inode == NULL) goto out;
 585
 586         error = init_inode(inode, dentry);
 587         if(error)
 588                 goto out_put;
 589
 590         error = -ENOMEM;
 591         name = dentry_name(dentry, 0);
 592         if(name == NULL)
 593                 goto out_put;
 594
 595         fd = file_create(name,
 596                          mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
 597                          mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
 598                          mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
 599         if(fd < 0)
 600                 error = fd;
 601         else error = read_name(inode, name);
 602
 603         kfree(name);
 604         if(error)
 605                 goto out_put;
 606
 607         HOSTFS_I(inode)->fd = fd;
 608         HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
 609         d_instantiate(dentry, inode);
 610         return(0);
 611
 612  out_put:
 613         iput(inode);
 614  out:
 615         return(error);
 616 }
 617
 618 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
 619                             struct nameidata *nd)
 620 {
 621         struct inode *inode;
 622         char *name;
 623         int err;
 624
 625         err = -ENOMEM;
 626         inode = iget(ino->i_sb, 0);
 627         if(inode == NULL)
 628                 goto out;
 629
 630         err = init_inode(inode, dentry);
 631         if(err)
 632                 goto out_put;
 633
 634         err = -ENOMEM;
 635         name = dentry_name(dentry, 0);
 636         if(name == NULL)
 637                 goto out_put;
 638
 639         err = read_name(inode, name);
 640         kfree(name);
 641         if(err == -ENOENT){
 642                 iput(inode);
 643                 inode = NULL;
 644         }
 645         else if(err)
 646                 goto out_put;
 647
 648         d_add(dentry, inode);
 649         dentry->d_op = &hostfs_dentry_ops;
 650         return(NULL);
 651
 652  out_put:
 653         iput(inode);
 654  out:
 655         return(ERR_PTR(err));
 656 }
 657
 658 static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
 659 {
 660         char *file;
 661         int len;
 662
 663         file = inode_name(ino, dentry->d_name.len + 1);
 664         if(file == NULL) return(NULL);
 665         strcat(file, "/");
 666         len = strlen(file);
 667         strncat(file, dentry->d_name.name, dentry->d_name.len);
 668         file[len + dentry->d_name.len] = '\0';
 669         return(file);
 670 }
 671
 672 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
 673 {
 674         char *from_name, *to_name;
 675         int err;
 676
 677         if((from_name = inode_dentry_name(ino, from)) == NULL)
 678                 return(-ENOMEM);
 679         to_name = dentry_name(to, 0);
 680         if(to_name == NULL){
 681                 kfree(from_name);
 682                 return(-ENOMEM);
 683         }
 684         err = link_file(to_name, from_name);
 685         kfree(from_name);
 686         kfree(to_name);
 687         return(err);
 688 }
 689
 690 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
 691 {
 692         char *file;
 693         int err;
 694
 695         if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
 696         if(append)
 697                 return(-EPERM);
 698
 699         err = unlink_file(file);
 700         kfree(file);
 701         return(err);
 702 }
 703
 704 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
 705 {
 706         char *file;
 707         int err;
 708
 709         if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
 710         err = make_symlink(file, to);
 711         kfree(file);
 712         return(err);
 713 }
 714
 715 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
 716 {
 717         char *file;
 718         int err;
 719
 720         if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
 721         err = do_mkdir(file, mode);
 722         kfree(file);
 723         return(err);
 724 }
 725
 726 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
 727 {
 728         char *file;
 729         int err;
 730
 731         if((file = inode_dentry_name(ino, dentry)) == NULL) return(-ENOMEM);
 732         err = do_rmdir(file);
 733         kfree(file);
 734         return(err);
 735 }
 736
 737 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 738 {
 739         struct inode *inode;
 740         char *name;
 741         int err = -ENOMEM;
 742
 743         inode = iget(dir->i_sb, 0);
 744         if(inode == NULL)
 745                 goto out;
 746
 747         err = init_inode(inode, dentry);
 748         if(err)
 749                 goto out_put;
 750
 751         err = -ENOMEM;
 752         name = dentry_name(dentry, 0);
 753         if(name == NULL)
 754                 goto out_put;
 755
 756         init_special_inode(inode, mode, dev);
 757         err = do_mknod(name, mode, dev);
 758         if(err)
 759                 goto out_free;
 760
 761         err = read_name(inode, name);
 762         kfree(name);
 763         if(err)
 764                 goto out_put;
 765
 766         d_instantiate(dentry, inode);
 767         return(0);
 768
 769  out_free:
 770         kfree(name);
 771  out_put:
 772         iput(inode);
 773  out:
 774         return(err);
 775 }
 776
 777 int hostfs_rename(struct inode *from_ino, struct dentry *from,
 778                   struct inode *to_ino, struct dentry *to)
 779 {
 780         char *from_name, *to_name;
 781         int err;
 782
 783         if((from_name = inode_dentry_name(from_ino, from)) == NULL)
 784                 return(-ENOMEM);
 785         if((to_name = inode_dentry_name(to_ino, to)) == NULL){
 786                 kfree(from_name);
 787                 return(-ENOMEM);
 788         }
 789         err = rename_file(from_name, to_name);
 790         kfree(from_name);
 791         kfree(to_name);
 792         return(err);
 793 }
 794
 795 void hostfs_truncate(struct inode *ino)
 796 {
 797         not_implemented();
 798 }
 799
 800 int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
 801 {
 802         char *name;
 803         int r = 0, w = 0, x = 0, err;
 804
 805         if (desired & MAY_READ) r = 1;
 806         if (desired & MAY_WRITE) w = 1;
 807         if (desired & MAY_EXEC) x = 1;
 808         name = inode_name(ino, 0);
 809         if (name == NULL) return(-ENOMEM);
 810
 811         if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
 812                         S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
 813                 err = 0;
 814         else
 815                 err = access_file(name, r, w, x);
 816         kfree(name);
 817         if(!err)
 818                 err = generic_permission(ino, desired, NULL);
 819         return err;
 820 }
 821
 822 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 823 {
 824         struct hostfs_iattr attrs;
 825         char *name;
 826         int err;
 827
 828         err = inode_change_ok(dentry->d_inode, attr);
 829         if (err)
 830                 return err;
 831
 832         if(append)
 833                 attr->ia_valid &= ~ATTR_SIZE;
 834
 835         attrs.ia_valid = 0;
 836         if(attr->ia_valid & ATTR_MODE){
 837                 attrs.ia_valid |= HOSTFS_ATTR_MODE;
 838                 attrs.ia_mode = attr->ia_mode;
 839         }
 840         if(attr->ia_valid & ATTR_UID){
 841                 attrs.ia_valid |= HOSTFS_ATTR_UID;
 842                 attrs.ia_uid = attr->ia_uid;
 843         }
 844         if(attr->ia_valid & ATTR_GID){
 845                 attrs.ia_valid |= HOSTFS_ATTR_GID;
 846                 attrs.ia_gid = attr->ia_gid;
 847         }
 848         if(attr->ia_valid & ATTR_SIZE){
 849                 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
 850                 attrs.ia_size = attr->ia_size;
 851         }
 852         if(attr->ia_valid & ATTR_ATIME){
 853                 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
 854                 attrs.ia_atime = attr->ia_atime;
 855         }
 856         if(attr->ia_valid & ATTR_MTIME){
 857                 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
 858                 attrs.ia_mtime = attr->ia_mtime;
 859         }
 860         if(attr->ia_valid & ATTR_CTIME){
 861                 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
 862                 attrs.ia_ctime = attr->ia_ctime;
 863         }
 864         if(attr->ia_valid & ATTR_ATIME_SET){
 865                 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
 866         }
 867         if(attr->ia_valid & ATTR_MTIME_SET){
 868                 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
 869         }
 870         name = dentry_name(dentry, 0);
 871         if(name == NULL) return(-ENOMEM);
 872         err = set_attr(name, &attrs);
 873         kfree(name);
 874         if(err)
 875                 return(err);
 876
 877         return(inode_setattr(dentry->d_inode, attr));
 878 }
 879
 880 int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 881            struct kstat *stat)
 882 {
 883         generic_fillattr(dentry->d_inode, stat);
 884         return(0);
 885 }
 886
 887 static struct inode_operations hostfs_iops = {
 888         .create         = hostfs_create,
 889         .link           = hostfs_link,
 890         .unlink         = hostfs_unlink,
 891         .symlink        = hostfs_symlink,
 892         .mkdir          = hostfs_mkdir,
 893         .rmdir          = hostfs_rmdir,
 894         .mknod          = hostfs_mknod,
 895         .rename         = hostfs_rename,
 896         .truncate       = hostfs_truncate,
 897         .permission     = hostfs_permission,
 898         .setattr        = hostfs_setattr,
 899         .getattr        = hostfs_getattr,
 900 };
 901
 902 static struct inode_operations hostfs_dir_iops = {
 903         .create         = hostfs_create,
 904         .lookup         = hostfs_lookup,
 905         .link           = hostfs_link,
 906         .unlink         = hostfs_unlink,
 907         .symlink        = hostfs_symlink,
 908         .mkdir          = hostfs_mkdir,
 909         .rmdir          = hostfs_rmdir,
 910         .mknod          = hostfs_mknod,
 911         .rename         = hostfs_rename,
 912         .truncate       = hostfs_truncate,
 913         .permission     = hostfs_permission,
 914         .setattr        = hostfs_setattr,
 915         .getattr        = hostfs_getattr,
 916 };
 917
 918 int hostfs_link_readpage(struct file *file, struct page *page)
 919 {
 920         char *buffer, *name;
 921         long long start;
 922         int err;
 923
 924         start = page->index << PAGE_CACHE_SHIFT;
 925         buffer = kmap(page);
 926         name = inode_name(page->mapping->host, 0);
 927         if(name == NULL) return(-ENOMEM);
 928         err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
 929         kfree(name);
 930         if(err == PAGE_CACHE_SIZE)
 931                 err = -E2BIG;
 932         else if(err > 0){
 933                 flush_dcache_page(page);
 934                 SetPageUptodate(page);
 935                 if (PageError(page)) ClearPageError(page);
 936                 err = 0;
 937         }
 938         kunmap(page);
 939         unlock_page(page);
 940         return(err);
 941 }
 942
 943 static struct address_space_operations hostfs_link_aops = {
 944         .readpage       = hostfs_link_readpage,
 945 };
 946
 947 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
 948 {
 949         struct inode *root_inode;
 950         char *name, *data = d;
 951         int err;
 952
 953         sb->s_blocksize = 1024;
 954         sb->s_blocksize_bits = 10;
 955         sb->s_magic = HOSTFS_SUPER_MAGIC;
 956         sb->s_op = &hostfs_sbops;
 957
 958         if((data == NULL) || (*data == '\0'))
 959                 data = root_ino;
 960
 961         err = -ENOMEM;
 962         name = kmalloc(strlen(data) + 1, GFP_KERNEL);
 963         if(name == NULL)
 964                 goto out;
 965
 966         strcpy(name, data);
 967
 968         root_inode = iget(sb, 0);
 969         if(root_inode == NULL)
 970                 goto out_free;
 971
 972         err = init_inode(root_inode, NULL);
 973         if(err)
 974                 goto out_put;
 975
 976         HOSTFS_I(root_inode)->host_filename = name;
 977
 978         err = -ENOMEM;
 979         sb->s_root = d_alloc_root(root_inode);
 980         if(sb->s_root == NULL)
 981                 goto out_put;
 982
 983         err = read_inode(root_inode);
 984         if(err){
 985                 /* No iput in this case because the dput does that for us */
 986                 dput(sb->s_root);
 987                 sb->s_root = NULL;
 988                 goto out_free;
 989         }
 990
 991         return(0);
 992
 993  out_put:
 994         iput(root_inode);
 995  out_free:
 996         kfree(name);
 997  out:
 998         return(err);
 999 }
1000
1001 static struct super_block *hostfs_read_sb(struct file_system_type *type,
1002                                              int flags, const char *dev_name,
1003                                              void *data)
1004 {
1005         return(get_sb_nodev(type, flags, data, hostfs_fill_sb_common));
1006 }
1007
1008 static struct file_system_type hostfs_type = {
1009         .owner          = THIS_MODULE,
1010         .name           = "hostfs",
1011         .get_sb         = hostfs_read_sb,
1012         .kill_sb        = kill_anon_super,
1013         .fs_flags       = 0,
1014 };
1015
1016 static int __init init_hostfs(void)
1017 {
1018         return(register_filesystem(&hostfs_type));
1019 }
1020
1021 static void __exit exit_hostfs(void)
1022 {
1023         unregister_filesystem(&hostfs_type);
1024 }
1025
1026 module_init(init_hostfs)
1027 module_exit(exit_hostfs)
1028 MODULE_LICENSE("GPL");
1029
1030 /*
1031  * Overrides for Emacs so that we follow Linus's tabbing style.
1032  * Emacs will notice this stuff at the end of the file and automatically
1033  * adjust the settings for this buffer only.  This must remain at the end
1034  * of the file.
1035  * ---------------------------------------------------------------------------
1036  * Local variables:
1037  * c-file-style: "linux"
1038  * End:
1039  */