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/module.h>
  12 #include <linux/init.h>
  13 #include <linux/slab.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/blkdev.h>
  16 #include <linux/list.h>
  17 #include <linux/statfs.h>
  18 #include <linux/kdev_t.h>
  19 #include <asm/uaccess.h>
  20 #include "hostfs.h"
  21 #include "kern_util.h"
  22 #include "kern.h"
  23 #include "init.h"
  24
  25 struct hostfs_inode_info {
  26         char *host_filename;
  27         int fd;
  28         int mode;
  29         struct inode vfs_inode;
  30 };
  31
  32 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
  33 {
  34         return(list_entry(inode, struct hostfs_inode_info, vfs_inode));
  35 }
  36
  37 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
  38
  39 int hostfs_d_delete(struct dentry *dentry)
  40 {
  41         return(1);
  42 }
  43
  44 struct dentry_operations hostfs_dentry_ops = {
  45         .d_delete               = hostfs_d_delete,
  46 };
  47
  48 /* Changed in hostfs_args before the kernel starts running */
  49 static char *root_ino = "";
  50 static int append = 0;
  51
  52 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
  53
  54 static const struct inode_operations hostfs_iops;
  55 static const struct inode_operations hostfs_dir_iops;
  56 static const struct address_space_operations hostfs_link_aops;
  57
  58 #ifndef MODULE
  59 static int __init hostfs_args(char *options, int *add)
  60 {
  61         char *ptr;
  62
  63         ptr = strchr(options, ',');
  64         if(ptr != NULL)
  65                 *ptr++ = '\0';
  66         if(*options != '\0')
  67                 root_ino = options;
  68
  69         options = ptr;
  70         while(options){
  71                 ptr = strchr(options, ',');
  72                 if(ptr != NULL)
  73                         *ptr++ = '\0';
  74                 if(*options != '\0'){
  75                         if(!strcmp(options, "append"))
  76                                 append = 1;
  77                         else printf("hostfs_args - unsupported option - %s\n",
  78                                     options);
  79                 }
  80                 options = ptr;
  81         }
  82         return(0);
  83 }
  84
  85 __uml_setup("hostfs=", hostfs_args,
  86 "hostfs=<root dir>,<flags>,...\n"
  87 "    This is used to set hostfs parameters.  The root directory argument\n"
  88 "    is used to confine all hostfs mounts to within the specified directory\n"
  89 "    tree on the host.  If this isn't specified, then a user inside UML can\n"
  90 "    mount anything on the host that's accessible to the user that's running\n"
  91 "    it.\n"
  92 "    The only flag currently supported is 'append', which specifies that all\n"
  93 "    files opened by hostfs will be opened in append mode.\n\n"
  94 );
  95 #endif
  96
  97 static char *dentry_name(struct dentry *dentry, int extra)
  98 {
  99         struct dentry *parent;
 100         char *root, *name;
 101         int len;
 102
 103         len = 0;
 104         parent = dentry;
 105         while(parent->d_parent != parent){
 106                 len += parent->d_name.len + 1;
 107                 parent = parent->d_parent;
 108         }
 109
 110         root = HOSTFS_I(parent->d_inode)->host_filename;
 111         len += strlen(root);
 112         name = kmalloc(len + extra + 1, GFP_KERNEL);
 113         if(name == NULL) return(NULL);
 114
 115         name[len] = '\0';
 116         parent = dentry;
 117         while(parent->d_parent != parent){
 118                 len -= parent->d_name.len + 1;
 119                 name[len] = '/';
 120                 strncpy(&name[len + 1], parent->d_name.name,
 121                         parent->d_name.len);
 122                 parent = parent->d_parent;
 123         }
 124         strncpy(name, root, strlen(root));
 125         return(name);
 126 }
 127
 128 static char *inode_name(struct inode *ino, int extra)
 129 {
 130         struct dentry *dentry;
 131
 132         dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
 133         return(dentry_name(dentry, extra));
 134 }
 135
 136 static int read_name(struct inode *ino, char *name)
 137 {
 138         /* The non-int inode fields are copied into ints by stat_file and
 139          * then copied into the inode because passing the actual pointers
 140          * in and having them treated as int * breaks on big-endian machines
 141          */
 142         int err;
 143         int i_mode, i_nlink, i_blksize;
 144         unsigned long long i_size;
 145         unsigned long long i_ino;
 146         unsigned long long i_blocks;
 147
 148         err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
 149                         &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
 150                         &ino->i_ctime, &i_blksize, &i_blocks);
 151         if(err)
 152                 return(err);
 153
 154         ino->i_ino = i_ino;
 155         ino->i_mode = i_mode;
 156         ino->i_nlink = i_nlink;
 157         ino->i_size = i_size;
 158         ino->i_blocks = i_blocks;
 159         return(0);
 160 }
 161
 162 static char *follow_link(char *link)
 163 {
 164         int len, n;
 165         char *name, *resolved, *end;
 166
 167         len = 64;
 168         while(1){
 169                 n = -ENOMEM;
 170                 name = kmalloc(len, GFP_KERNEL);
 171                 if(name == NULL)
 172                         goto out;
 173
 174                 n = do_readlink(link, name, len);
 175                 if(n < len)
 176                         break;
 177                 len *= 2;
 178                 kfree(name);
 179         }
 180         if(n < 0)
 181                 goto out_free;
 182
 183         if(*name == '/')
 184                 return(name);
 185
 186         end = strrchr(link, '/');
 187         if(end == NULL)
 188                 return(name);
 189
 190         *(end + 1) = '\0';
 191         len = strlen(link) + strlen(name) + 1;
 192
 193         resolved = kmalloc(len, GFP_KERNEL);
 194         if(resolved == NULL){
 195                 n = -ENOMEM;
 196                 goto out_free;
 197         }
 198
 199         sprintf(resolved, "%s%s", link, name);
 200         kfree(name);
 201         kfree(link);
 202         return(resolved);
 203
 204  out_free:
 205         kfree(name);
 206  out:
 207         return(ERR_PTR(n));
 208 }
 209
 210 static int read_inode(struct inode *ino)
 211 {
 212         char *name;
 213         int err = 0;
 214
 215         /* Unfortunately, we are called from iget() when we don't have a dentry
 216          * allocated yet.
 217          */
 218         if(list_empty(&ino->i_dentry))
 219                 goto out;
 220
 221         err = -ENOMEM;
 222         name = inode_name(ino, 0);
 223         if(name == NULL)
 224                 goto out;
 225
 226         if(file_type(name, NULL, NULL) == OS_TYPE_SYMLINK){
 227                 name = follow_link(name);
 228                 if(IS_ERR(name)){
 229                         err = PTR_ERR(name);
 230                         goto out;
 231                 }
 232         }
 233
 234         err = read_name(ino, name);
 235         kfree(name);
 236  out:
 237         return(err);
 238 }
 239
 240 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
 241 {
 242         /* do_statfs uses struct statfs64 internally, but the linux kernel
 243          * struct statfs still has 32-bit versions for most of these fields,
 244          * so we convert them here
 245          */
 246         int err;
 247         long long f_blocks;
 248         long long f_bfree;
 249         long long f_bavail;
 250         long long f_files;
 251         long long f_ffree;
 252
 253         err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
 254                         &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
 255                         &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
 256                         &sf->f_namelen, sf->f_spare);
 257         if(err) return(err);
 258         sf->f_blocks = f_blocks;
 259         sf->f_bfree = f_bfree;
 260         sf->f_bavail = f_bavail;
 261         sf->f_files = f_files;
 262         sf->f_ffree = f_ffree;
 263         sf->f_type = HOSTFS_SUPER_MAGIC;
 264         return(0);
 265 }
 266
 267 static struct inode *hostfs_alloc_inode(struct super_block *sb)
 268 {
 269         struct hostfs_inode_info *hi;
 270
 271         hi = kmalloc(sizeof(*hi), GFP_KERNEL);
 272         if(hi == NULL)
 273                 return(NULL);
 274
 275         *hi = ((struct hostfs_inode_info) { .host_filename      = NULL,
 276                                             .fd                 = -1,
 277                                             .mode               = 0 });
 278         inode_init_once(&hi->vfs_inode);
 279         return(&hi->vfs_inode);
 280 }
 281
 282 static void hostfs_delete_inode(struct inode *inode)
 283 {
 284         truncate_inode_pages(&inode->i_data, 0);
 285         if(HOSTFS_I(inode)->fd != -1) {
 286                 close_file(&HOSTFS_I(inode)->fd);
 287                 HOSTFS_I(inode)->fd = -1;
 288         }
 289         clear_inode(inode);
 290 }
 291
 292 static void hostfs_destroy_inode(struct inode *inode)
 293 {
 294         kfree(HOSTFS_I(inode)->host_filename);
 295
 296         /*XXX: This should not happen, probably. The check is here for
 297          * additional safety.*/
 298         if(HOSTFS_I(inode)->fd != -1) {
 299                 close_file(&HOSTFS_I(inode)->fd);
 300                 printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
 301         }
 302
 303         kfree(HOSTFS_I(inode));
 304 }
 305
 306 static void hostfs_read_inode(struct inode *inode)
 307 {
 308         read_inode(inode);
 309 }
 310
 311 static const struct super_operations hostfs_sbops = {
 312         .alloc_inode    = hostfs_alloc_inode,
 313         .drop_inode     = generic_delete_inode,
 314         .delete_inode   = hostfs_delete_inode,
 315         .destroy_inode  = hostfs_destroy_inode,
 316         .read_inode     = hostfs_read_inode,
 317         .statfs         = hostfs_statfs,
 318 };
 319
 320 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
 321 {
 322         void *dir;
 323         char *name;
 324         unsigned long long next, ino;
 325         int error, len;
 326
 327         name = dentry_name(file->f_path.dentry, 0);
 328         if(name == NULL) return(-ENOMEM);
 329         dir = open_dir(name, &error);
 330         kfree(name);
 331         if(dir == NULL) return(-error);
 332         next = file->f_pos;
 333         while((name = read_dir(dir, &next, &ino, &len)) != NULL){
 334                 error = (*filldir)(ent, name, len, file->f_pos,
 335                                    ino, DT_UNKNOWN);
 336                 if(error) break;
 337                 file->f_pos = next;
 338         }
 339         close_dir(dir);
 340         return(0);
 341 }
 342
 343 int hostfs_file_open(struct inode *ino, struct file *file)
 344 {
 345         char *name;
 346         int mode = 0, r = 0, w = 0, fd;
 347
 348         mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
 349         if((mode & HOSTFS_I(ino)->mode) == mode)
 350                 return(0);
 351
 352         /* The file may already have been opened, but with the wrong access,
 353          * so this resets things and reopens the file with the new access.
 354          */
 355         if(HOSTFS_I(ino)->fd != -1){
 356                 close_file(&HOSTFS_I(ino)->fd);
 357                 HOSTFS_I(ino)->fd = -1;
 358         }
 359
 360         HOSTFS_I(ino)->mode |= mode;
 361         if(HOSTFS_I(ino)->mode & FMODE_READ)
 362                 r = 1;
 363         if(HOSTFS_I(ino)->mode & FMODE_WRITE)
 364                 w = 1;
 365         if(w)
 366                 r = 1;
 367
 368         name = dentry_name(file->f_path.dentry, 0);
 369         if(name == NULL)
 370                 return(-ENOMEM);
 371
 372         fd = open_file(name, r, w, append);
 373         kfree(name);
 374         if(fd < 0) return(fd);
 375         FILE_HOSTFS_I(file)->fd = fd;
 376
 377         return(0);
 378 }
 379
 380 int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 381 {
 382         return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync);
 383 }
 384
 385 static const struct file_operations hostfs_file_fops = {
 386         .llseek         = generic_file_llseek,
 387         .read           = do_sync_read,
 388         .sendfile       = generic_file_sendfile,
 389         .aio_read       = generic_file_aio_read,
 390         .aio_write      = generic_file_aio_write,
 391         .write          = do_sync_write,
 392         .mmap           = generic_file_mmap,
 393         .open           = hostfs_file_open,
 394         .release        = NULL,
 395         .fsync          = hostfs_fsync,
 396 };
 397
 398 static const struct file_operations hostfs_dir_fops = {
 399         .llseek         = generic_file_llseek,
 400         .readdir        = hostfs_readdir,
 401         .read           = generic_read_dir,
 402 };
 403
 404 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 405 {
 406         struct address_space *mapping = page->mapping;
 407         struct inode *inode = mapping->host;
 408         char *buffer;
 409         unsigned long long base;
 410         int count = PAGE_CACHE_SIZE;
 411         int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
 412         int err;
 413
 414         if (page->index >= end_index)
 415                 count = inode->i_size & (PAGE_CACHE_SIZE-1);
 416
 417         buffer = kmap(page);
 418         base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
 419
 420         err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 421         if(err != count){
 422                 ClearPageUptodate(page);
 423                 goto out;
 424         }
 425
 426         if (base > inode->i_size)
 427                 inode->i_size = base;
 428
 429         if (PageError(page))
 430                 ClearPageError(page);
 431         err = 0;
 432
 433  out:
 434         kunmap(page);
 435
 436         unlock_page(page);
 437         return err;
 438 }
 439
 440 int hostfs_readpage(struct file *file, struct page *page)
 441 {
 442         char *buffer;
 443         long long start;
 444         int err = 0;
 445
 446         start = (long long) page->index << PAGE_CACHE_SHIFT;
 447         buffer = kmap(page);
 448         err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
 449                         PAGE_CACHE_SIZE);
 450         if(err < 0) goto out;
 451
 452         memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
 453
 454         flush_dcache_page(page);
 455         SetPageUptodate(page);
 456         if (PageError(page)) ClearPageError(page);
 457         err = 0;
 458  out:
 459         kunmap(page);
 460         unlock_page(page);
 461         return(err);
 462 }
 463
 464 int hostfs_prepare_write(struct file *file, struct page *page,
 465                          unsigned int from, unsigned int to)
 466 {
 467         char *buffer;
 468         long long start, tmp;
 469         int err;
 470
 471         start = (long long) page->index << PAGE_CACHE_SHIFT;
 472         buffer = kmap(page);
 473         if(from != 0){
 474                 tmp = start;
 475                 err = read_file(FILE_HOSTFS_I(file)->fd, &tmp, buffer,
 476                                 from);
 477                 if(err < 0) goto out;
 478         }
 479         if(to != PAGE_CACHE_SIZE){
 480                 start += to;
 481                 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer + to,
 482                                 PAGE_CACHE_SIZE - to);
 483                 if(err < 0) goto out;
 484         }
 485         err = 0;
 486  out:
 487         kunmap(page);
 488         return(err);
 489 }
 490
 491 int hostfs_commit_write(struct file *file, struct page *page, unsigned from,
 492                  unsigned to)
 493 {
 494         struct address_space *mapping = page->mapping;
 495         struct inode *inode = mapping->host;
 496         char *buffer;
 497         long long start;
 498         int err = 0;
 499
 500         start = (((long long) page->index) << PAGE_CACHE_SHIFT) + from;
 501         buffer = kmap(page);
 502         err = write_file(FILE_HOSTFS_I(file)->fd, &start, buffer + from,
 503                          to - from);
 504         if(err > 0) err = 0;
 505
 506         /* Actually, if !err, write_file has added to-from to start, so, despite
 507          * the appearance, we are comparing i_size against the _last_ written
 508          * location, as we should. */
 509
 510         if(!err && (start > inode->i_size))
 511                 inode->i_size = start;
 512
 513         kunmap(page);
 514         return(err);
 515 }
 516
 517 static const 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, MAJOR(dev), MINOR(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 int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
 796 {
 797         char *name;
 798         int r = 0, w = 0, x = 0, err;
 799
 800         if (desired & MAY_READ) r = 1;
 801         if (desired & MAY_WRITE) w = 1;
 802         if (desired & MAY_EXEC) x = 1;
 803         name = inode_name(ino, 0);
 804         if (name == NULL) return(-ENOMEM);
 805
 806         if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
 807                         S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
 808                 err = 0;
 809         else
 810                 err = access_file(name, r, w, x);
 811         kfree(name);
 812         if(!err)
 813                 err = generic_permission(ino, desired, NULL);
 814         return err;
 815 }
 816
 817 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 818 {
 819         struct hostfs_iattr attrs;
 820         char *name;
 821         int err;
 822
 823         err = inode_change_ok(dentry->d_inode, attr);
 824         if (err)
 825                 return err;
 826
 827         if(append)
 828                 attr->ia_valid &= ~ATTR_SIZE;
 829
 830         attrs.ia_valid = 0;
 831         if(attr->ia_valid & ATTR_MODE){
 832                 attrs.ia_valid |= HOSTFS_ATTR_MODE;
 833                 attrs.ia_mode = attr->ia_mode;
 834         }
 835         if(attr->ia_valid & ATTR_UID){
 836                 attrs.ia_valid |= HOSTFS_ATTR_UID;
 837                 attrs.ia_uid = attr->ia_uid;
 838         }
 839         if(attr->ia_valid & ATTR_GID){
 840                 attrs.ia_valid |= HOSTFS_ATTR_GID;
 841                 attrs.ia_gid = attr->ia_gid;
 842         }
 843         if(attr->ia_valid & ATTR_SIZE){
 844                 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
 845                 attrs.ia_size = attr->ia_size;
 846         }
 847         if(attr->ia_valid & ATTR_ATIME){
 848                 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
 849                 attrs.ia_atime = attr->ia_atime;
 850         }
 851         if(attr->ia_valid & ATTR_MTIME){
 852                 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
 853                 attrs.ia_mtime = attr->ia_mtime;
 854         }
 855         if(attr->ia_valid & ATTR_CTIME){
 856                 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
 857                 attrs.ia_ctime = attr->ia_ctime;
 858         }
 859         if(attr->ia_valid & ATTR_ATIME_SET){
 860                 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
 861         }
 862         if(attr->ia_valid & ATTR_MTIME_SET){
 863                 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
 864         }
 865         name = dentry_name(dentry, 0);
 866         if(name == NULL) return(-ENOMEM);
 867         err = set_attr(name, &attrs);
 868         kfree(name);
 869         if(err)
 870                 return(err);
 871
 872         return(inode_setattr(dentry->d_inode, attr));
 873 }
 874
 875 int hostfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
 876            struct kstat *stat)
 877 {
 878         generic_fillattr(dentry->d_inode, stat);
 879         return(0);
 880 }
 881
 882 static const struct inode_operations hostfs_iops = {
 883         .create         = hostfs_create,
 884         .link           = hostfs_link,
 885         .unlink         = hostfs_unlink,
 886         .symlink        = hostfs_symlink,
 887         .mkdir          = hostfs_mkdir,
 888         .rmdir          = hostfs_rmdir,
 889         .mknod          = hostfs_mknod,
 890         .rename         = hostfs_rename,
 891         .permission     = hostfs_permission,
 892         .setattr        = hostfs_setattr,
 893         .getattr        = hostfs_getattr,
 894 };
 895
 896 static const struct inode_operations hostfs_dir_iops = {
 897         .create         = hostfs_create,
 898         .lookup         = hostfs_lookup,
 899         .link           = hostfs_link,
 900         .unlink         = hostfs_unlink,
 901         .symlink        = hostfs_symlink,
 902         .mkdir          = hostfs_mkdir,
 903         .rmdir          = hostfs_rmdir,
 904         .mknod          = hostfs_mknod,
 905         .rename         = hostfs_rename,
 906         .permission     = hostfs_permission,
 907         .setattr        = hostfs_setattr,
 908         .getattr        = hostfs_getattr,
 909 };
 910
 911 int hostfs_link_readpage(struct file *file, struct page *page)
 912 {
 913         char *buffer, *name;
 914         int err;
 915
 916         buffer = kmap(page);
 917         name = inode_name(page->mapping->host, 0);
 918         if(name == NULL) return(-ENOMEM);
 919         err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
 920         kfree(name);
 921         if(err == PAGE_CACHE_SIZE)
 922                 err = -E2BIG;
 923         else if(err > 0){
 924                 flush_dcache_page(page);
 925                 SetPageUptodate(page);
 926                 if (PageError(page)) ClearPageError(page);
 927                 err = 0;
 928         }
 929         kunmap(page);
 930         unlock_page(page);
 931         return(err);
 932 }
 933
 934 static const struct address_space_operations hostfs_link_aops = {
 935         .readpage       = hostfs_link_readpage,
 936 };
 937
 938 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
 939 {
 940         struct inode *root_inode;
 941         char *host_root_path, *req_root = d;
 942         int err;
 943
 944         sb->s_blocksize = 1024;
 945         sb->s_blocksize_bits = 10;
 946         sb->s_magic = HOSTFS_SUPER_MAGIC;
 947         sb->s_op = &hostfs_sbops;
 948
 949         /* NULL is printed as <NULL> by sprintf: avoid that. */
 950         if (req_root == NULL)
 951                 req_root = "";
 952
 953         err = -ENOMEM;
 954         host_root_path = kmalloc(strlen(root_ino) + 1
 955                                  + strlen(req_root) + 1, GFP_KERNEL);
 956         if(host_root_path == NULL)
 957                 goto out;
 958
 959         sprintf(host_root_path, "%s/%s", root_ino, req_root);
 960
 961         root_inode = iget(sb, 0);
 962         if(root_inode == NULL)
 963                 goto out_free;
 964
 965         err = init_inode(root_inode, NULL);
 966         if(err)
 967                 goto out_put;
 968
 969         HOSTFS_I(root_inode)->host_filename = host_root_path;
 970         /* Avoid that in the error path, iput(root_inode) frees again
 971          * host_root_path through hostfs_destroy_inode! */
 972         host_root_path = NULL;
 973
 974         err = -ENOMEM;
 975         sb->s_root = d_alloc_root(root_inode);
 976         if(sb->s_root == NULL)
 977                 goto out_put;
 978
 979         err = read_inode(root_inode);
 980         if(err){
 981                 /* No iput in this case because the dput does that for us */
 982                 dput(sb->s_root);
 983                 sb->s_root = NULL;
 984                 goto out;
 985         }
 986
 987         return(0);
 988
 989  out_put:
 990         iput(root_inode);
 991  out_free:
 992         kfree(host_root_path);
 993  out:
 994         return(err);
 995 }
 996
 997 static int hostfs_read_sb(struct file_system_type *type,
 998                           int flags, const char *dev_name,
 999                           void *data, struct vfsmount *mnt)
1000 {
1001         return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
1002 }
1003
1004 static struct file_system_type hostfs_type = {
1005         .owner          = THIS_MODULE,
1006         .name           = "hostfs",
1007         .get_sb         = hostfs_read_sb,
1008         .kill_sb        = kill_anon_super,
1009         .fs_flags       = 0,
1010 };
1011
1012 static int __init init_hostfs(void)
1013 {
1014         return(register_filesystem(&hostfs_type));
1015 }
1016
1017 static void __exit exit_hostfs(void)
1018 {
1019         unregister_filesystem(&hostfs_type);
1020 }
1021
1022 module_init(init_hostfs)
1023 module_exit(exit_hostfs)
1024 MODULE_LICENSE("GPL");
1025
1026 /*
1027  * Overrides for Emacs so that we follow Linus's tabbing style.
1028  * Emacs will notice this stuff at the end of the file and automatically
1029  * adjust the settings for this buffer only.  This must remain at the end
1030  * of the file.
1031  * ---------------------------------------------------------------------------
1032  * Local variables:
1033  * c-file-style: "linux"
1034  * End:
1035  */