fs/hostfs/hostfs_kern.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.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/fs.h>
  10 #include <linux/module.h>
  11 #include <linux/mm.h>
  12 #include <linux/pagemap.h>
  13 #include <linux/statfs.h>
  14 #include "hostfs.h"
  15 #include "init.h"
  16 #include "kern.h"
  17
  18 struct hostfs_inode_info {
  19         char *host_filename;
  20         int fd;
  21         int mode;
  22         struct inode vfs_inode;
  23 };
  24
  25 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode)
  26 {
  27         return list_entry(inode, struct hostfs_inode_info, vfs_inode);
  28 }
  29
  30 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode)
  31
  32 int hostfs_d_delete(struct dentry *dentry)
  33 {
  34         return 1;
  35 }
  36
  37 struct dentry_operations hostfs_dentry_ops = {
  38         .d_delete               = hostfs_d_delete,
  39 };
  40
  41 /* Changed in hostfs_args before the kernel starts running */
  42 static char *root_ino = "";
  43 static int append = 0;
  44
  45 #define HOSTFS_SUPER_MAGIC 0x00c0ffee
  46
  47 static const struct inode_operations hostfs_iops;
  48 static const struct inode_operations hostfs_dir_iops;
  49 static const struct address_space_operations hostfs_link_aops;
  50
  51 #ifndef MODULE
  52 static int __init hostfs_args(char *options, int *add)
  53 {
  54         char *ptr;
  55
  56         ptr = strchr(options, ',');
  57         if (ptr != NULL)
  58                 *ptr++ = '\0';
  59         if (*options != '\0')
  60                 root_ino = options;
  61
  62         options = ptr;
  63         while (options) {
  64                 ptr = strchr(options, ',');
  65                 if (ptr != NULL)
  66                         *ptr++ = '\0';
  67                 if (*options != '\0') {
  68                         if (!strcmp(options, "append"))
  69                                 append = 1;
  70                         else printf("hostfs_args - unsupported option - %s\n",
  71                                     options);
  72                 }
  73                 options = ptr;
  74         }
  75         return 0;
  76 }
  77
  78 __uml_setup("hostfs=", hostfs_args,
  79 "hostfs=<root dir>,<flags>,...\n"
  80 "    This is used to set hostfs parameters.  The root directory argument\n"
  81 "    is used to confine all hostfs mounts to within the specified directory\n"
  82 "    tree on the host.  If this isn't specified, then a user inside UML can\n"
  83 "    mount anything on the host that's accessible to the user that's running\n"
  84 "    it.\n"
  85 "    The only flag currently supported is 'append', which specifies that all\n"
  86 "    files opened by hostfs will be opened in append mode.\n\n"
  87 );
  88 #endif
  89
  90 static char *dentry_name(struct dentry *dentry, int extra)
  91 {
  92         struct dentry *parent;
  93         char *root, *name;
  94         int len;
  95
  96         len = 0;
  97         parent = dentry;
  98         while (parent->d_parent != parent) {
  99                 len += parent->d_name.len + 1;
 100                 parent = parent->d_parent;
 101         }
 102
 103         root = HOSTFS_I(parent->d_inode)->host_filename;
 104         len += strlen(root);
 105         name = kmalloc(len + extra + 1, GFP_KERNEL);
 106         if (name == NULL)
 107                 return NULL;
 108
 109         name[len] = '\0';
 110         parent = dentry;
 111         while (parent->d_parent != parent) {
 112                 len -= parent->d_name.len + 1;
 113                 name[len] = '/';
 114                 strncpy(&name[len + 1], parent->d_name.name,
 115                         parent->d_name.len);
 116                 parent = parent->d_parent;
 117         }
 118         strncpy(name, root, strlen(root));
 119         return name;
 120 }
 121
 122 static char *inode_name(struct inode *ino, int extra)
 123 {
 124         struct dentry *dentry;
 125
 126         dentry = list_entry(ino->i_dentry.next, struct dentry, d_alias);
 127         return dentry_name(dentry, extra);
 128 }
 129
 130 static int read_name(struct inode *ino, char *name)
 131 {
 132         /*
 133          * The non-int inode fields are copied into ints by stat_file and
 134          * then copied into the inode because passing the actual pointers
 135          * in and having them treated as int * breaks on big-endian machines
 136          */
 137         int err;
 138         int i_mode, i_nlink, i_blksize;
 139         unsigned long long i_size;
 140         unsigned long long i_ino;
 141         unsigned long long i_blocks;
 142
 143         err = stat_file(name, &i_ino, &i_mode, &i_nlink, &ino->i_uid,
 144                         &ino->i_gid, &i_size, &ino->i_atime, &ino->i_mtime,
 145                         &ino->i_ctime, &i_blksize, &i_blocks, -1);
 146         if (err)
 147                 return err;
 148
 149         ino->i_ino = i_ino;
 150         ino->i_mode = i_mode;
 151         ino->i_nlink = i_nlink;
 152         ino->i_size = i_size;
 153         ino->i_blocks = i_blocks;
 154         return 0;
 155 }
 156
 157 static char *follow_link(char *link)
 158 {
 159         int len, n;
 160         char *name, *resolved, *end;
 161
 162         len = 64;
 163         while (1) {
 164                 n = -ENOMEM;
 165                 name = kmalloc(len, GFP_KERNEL);
 166                 if (name == NULL)
 167                         goto out;
 168
 169                 n = do_readlink(link, name, len);
 170                 if (n < len)
 171                         break;
 172                 len *= 2;
 173                 kfree(name);
 174         }
 175         if (n < 0)
 176                 goto out_free;
 177
 178         if (*name == '/')
 179                 return name;
 180
 181         end = strrchr(link, '/');
 182         if (end == NULL)
 183                 return name;
 184
 185         *(end + 1) = '\0';
 186         len = strlen(link) + strlen(name) + 1;
 187
 188         resolved = kmalloc(len, GFP_KERNEL);
 189         if (resolved == NULL) {
 190                 n = -ENOMEM;
 191                 goto out_free;
 192         }
 193
 194         sprintf(resolved, "%s%s", link, name);
 195         kfree(name);
 196         kfree(link);
 197         return resolved;
 198
 199  out_free:
 200         kfree(name);
 201  out:
 202         return ERR_PTR(n);
 203 }
 204
 205 static int hostfs_read_inode(struct inode *ino)
 206 {
 207         char *name;
 208         int err = 0;
 209
 210         /*
 211          * Unfortunately, we are called from iget() when we don't have a dentry
 212          * allocated yet.
 213          */
 214         if (list_empty(&ino->i_dentry))
 215                 goto out;
 216
 217         err = -ENOMEM;
 218         name = inode_name(ino, 0);
 219         if (name == NULL)
 220                 goto out;
 221
 222         if (file_type(name, NULL, NULL) == OS_TYPE_SYMLINK) {
 223                 name = follow_link(name);
 224                 if (IS_ERR(name)) {
 225                         err = PTR_ERR(name);
 226                         goto out;
 227                 }
 228         }
 229
 230         err = read_name(ino, name);
 231         kfree(name);
 232  out:
 233         return err;
 234 }
 235
 236 static struct inode *hostfs_iget(struct super_block *sb)
 237 {
 238         struct inode *inode;
 239         long ret;
 240
 241         inode = iget_locked(sb, 0);
 242         if (!inode)
 243                 return ERR_PTR(-ENOMEM);
 244         if (inode->i_state & I_NEW) {
 245                 ret = hostfs_read_inode(inode);
 246                 if (ret < 0) {
 247                         iget_failed(inode);
 248                         return ERR_PTR(ret);
 249                 }
 250                 unlock_new_inode(inode);
 251         }
 252         return inode;
 253 }
 254
 255 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf)
 256 {
 257         /*
 258          * do_statfs uses struct statfs64 internally, but the linux kernel
 259          * struct statfs still has 32-bit versions for most of these fields,
 260          * so we convert them here
 261          */
 262         int err;
 263         long long f_blocks;
 264         long long f_bfree;
 265         long long f_bavail;
 266         long long f_files;
 267         long long f_ffree;
 268
 269         err = do_statfs(HOSTFS_I(dentry->d_sb->s_root->d_inode)->host_filename,
 270                         &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files,
 271                         &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid),
 272                         &sf->f_namelen, sf->f_spare);
 273         if (err)
 274                 return err;
 275         sf->f_blocks = f_blocks;
 276         sf->f_bfree = f_bfree;
 277         sf->f_bavail = f_bavail;
 278         sf->f_files = f_files;
 279         sf->f_ffree = f_ffree;
 280         sf->f_type = HOSTFS_SUPER_MAGIC;
 281         return 0;
 282 }
 283
 284 static struct inode *hostfs_alloc_inode(struct super_block *sb)
 285 {
 286         struct hostfs_inode_info *hi;
 287
 288         hi = kmalloc(sizeof(*hi), GFP_KERNEL);
 289         if (hi == NULL)
 290                 return NULL;
 291
 292         *hi = ((struct hostfs_inode_info) { .host_filename      = NULL,
 293                                             .fd                 = -1,
 294                                             .mode               = 0 });
 295         inode_init_once(&hi->vfs_inode);
 296         return &hi->vfs_inode;
 297 }
 298
 299 static void hostfs_delete_inode(struct inode *inode)
 300 {
 301         truncate_inode_pages(&inode->i_data, 0);
 302         if (HOSTFS_I(inode)->fd != -1) {
 303                 close_file(&HOSTFS_I(inode)->fd);
 304                 HOSTFS_I(inode)->fd = -1;
 305         }
 306         clear_inode(inode);
 307 }
 308
 309 static void hostfs_destroy_inode(struct inode *inode)
 310 {
 311         kfree(HOSTFS_I(inode)->host_filename);
 312
 313         /*
 314          * XXX: This should not happen, probably. The check is here for
 315          * additional safety.
 316          */
 317         if (HOSTFS_I(inode)->fd != -1) {
 318                 close_file(&HOSTFS_I(inode)->fd);
 319                 printk(KERN_DEBUG "Closing host fd in .destroy_inode\n");
 320         }
 321
 322         kfree(HOSTFS_I(inode));
 323 }
 324
 325 static const struct super_operations hostfs_sbops = {
 326         .alloc_inode    = hostfs_alloc_inode,
 327         .drop_inode     = generic_delete_inode,
 328         .delete_inode   = hostfs_delete_inode,
 329         .destroy_inode  = hostfs_destroy_inode,
 330         .statfs         = hostfs_statfs,
 331 };
 332
 333 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir)
 334 {
 335         void *dir;
 336         char *name;
 337         unsigned long long next, ino;
 338         int error, len;
 339
 340         name = dentry_name(file->f_path.dentry, 0);
 341         if (name == NULL)
 342                 return -ENOMEM;
 343         dir = open_dir(name, &error);
 344         kfree(name);
 345         if (dir == NULL)
 346                 return -error;
 347         next = file->f_pos;
 348         while ((name = read_dir(dir, &next, &ino, &len)) != NULL) {
 349                 error = (*filldir)(ent, name, len, file->f_pos,
 350                                    ino, DT_UNKNOWN);
 351                 if (error) break;
 352                 file->f_pos = next;
 353         }
 354         close_dir(dir);
 355         return 0;
 356 }
 357
 358 int hostfs_file_open(struct inode *ino, struct file *file)
 359 {
 360         char *name;
 361         int mode = 0, r = 0, w = 0, fd;
 362
 363         mode = file->f_mode & (FMODE_READ | FMODE_WRITE);
 364         if ((mode & HOSTFS_I(ino)->mode) == mode)
 365                 return 0;
 366
 367         /*
 368          * The file may already have been opened, but with the wrong access,
 369          * so this resets things and reopens the file with the new access.
 370          */
 371         if (HOSTFS_I(ino)->fd != -1) {
 372                 close_file(&HOSTFS_I(ino)->fd);
 373                 HOSTFS_I(ino)->fd = -1;
 374         }
 375
 376         HOSTFS_I(ino)->mode |= mode;
 377         if (HOSTFS_I(ino)->mode & FMODE_READ)
 378                 r = 1;
 379         if (HOSTFS_I(ino)->mode & FMODE_WRITE)
 380                 w = 1;
 381         if (w)
 382                 r = 1;
 383
 384         name = dentry_name(file->f_path.dentry, 0);
 385         if (name == NULL)
 386                 return -ENOMEM;
 387
 388         fd = open_file(name, r, w, append);
 389         kfree(name);
 390         if (fd < 0)
 391                 return fd;
 392         FILE_HOSTFS_I(file)->fd = fd;
 393
 394         return 0;
 395 }
 396
 397 int hostfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 398 {
 399         return fsync_file(HOSTFS_I(dentry->d_inode)->fd, datasync);
 400 }
 401
 402 static const struct file_operations hostfs_file_fops = {
 403         .llseek         = generic_file_llseek,
 404         .read           = do_sync_read,
 405         .splice_read    = generic_file_splice_read,
 406         .aio_read       = generic_file_aio_read,
 407         .aio_write      = generic_file_aio_write,
 408         .write          = do_sync_write,
 409         .mmap           = generic_file_mmap,
 410         .open           = hostfs_file_open,
 411         .release        = NULL,
 412         .fsync          = hostfs_fsync,
 413 };
 414
 415 static const struct file_operations hostfs_dir_fops = {
 416         .llseek         = generic_file_llseek,
 417         .readdir        = hostfs_readdir,
 418         .read           = generic_read_dir,
 419 };
 420
 421 int hostfs_writepage(struct page *page, struct writeback_control *wbc)
 422 {
 423         struct address_space *mapping = page->mapping;
 424         struct inode *inode = mapping->host;
 425         char *buffer;
 426         unsigned long long base;
 427         int count = PAGE_CACHE_SIZE;
 428         int end_index = inode->i_size >> PAGE_CACHE_SHIFT;
 429         int err;
 430
 431         if (page->index >= end_index)
 432                 count = inode->i_size & (PAGE_CACHE_SIZE-1);
 433
 434         buffer = kmap(page);
 435         base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT;
 436
 437         err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count);
 438         if (err != count) {
 439                 ClearPageUptodate(page);
 440                 goto out;
 441         }
 442
 443         if (base > inode->i_size)
 444                 inode->i_size = base;
 445
 446         if (PageError(page))
 447                 ClearPageError(page);
 448         err = 0;
 449
 450  out:
 451         kunmap(page);
 452
 453         unlock_page(page);
 454         return err;
 455 }
 456
 457 int hostfs_readpage(struct file *file, struct page *page)
 458 {
 459         char *buffer;
 460         long long start;
 461         int err = 0;
 462
 463         start = (long long) page->index << PAGE_CACHE_SHIFT;
 464         buffer = kmap(page);
 465         err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer,
 466                         PAGE_CACHE_SIZE);
 467         if (err < 0)
 468                 goto out;
 469
 470         memset(&buffer[err], 0, PAGE_CACHE_SIZE - err);
 471
 472         flush_dcache_page(page);
 473         SetPageUptodate(page);
 474         if (PageError(page)) ClearPageError(page);
 475         err = 0;
 476  out:
 477         kunmap(page);
 478         unlock_page(page);
 479         return err;
 480 }
 481
 482 int hostfs_write_begin(struct file *file, struct address_space *mapping,
 483                         loff_t pos, unsigned len, unsigned flags,
 484                         struct page **pagep, void **fsdata)
 485 {
 486         pgoff_t index = pos >> PAGE_CACHE_SHIFT;
 487
 488         *pagep = __grab_cache_page(mapping, index);
 489         if (!*pagep)
 490                 return -ENOMEM;
 491         return 0;
 492 }
 493
 494 int hostfs_write_end(struct file *file, struct address_space *mapping,
 495                         loff_t pos, unsigned len, unsigned copied,
 496                         struct page *page, void *fsdata)
 497 {
 498         struct inode *inode = mapping->host;
 499         void *buffer;
 500         unsigned from = pos & (PAGE_CACHE_SIZE - 1);
 501         int err;
 502
 503         buffer = kmap(page);
 504         err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied);
 505         kunmap(page);
 506
 507         if (!PageUptodate(page) && err == PAGE_CACHE_SIZE)
 508                 SetPageUptodate(page);
 509
 510         /*
 511          * If err > 0, write_file has added err to pos, so we are comparing
 512          * i_size against the last byte written.
 513          */
 514         if (err > 0 && (pos > inode->i_size))
 515                 inode->i_size = pos;
 516         unlock_page(page);
 517         page_cache_release(page);
 518
 519         return err;
 520 }
 521
 522 static const struct address_space_operations hostfs_aops = {
 523         .writepage      = hostfs_writepage,
 524         .readpage       = hostfs_readpage,
 525         .set_page_dirty = __set_page_dirty_nobuffers,
 526         .write_begin    = hostfs_write_begin,
 527         .write_end      = hostfs_write_end,
 528 };
 529
 530 static int init_inode(struct inode *inode, struct dentry *dentry)
 531 {
 532         char *name;
 533         int type, err = -ENOMEM;
 534         int maj, min;
 535         dev_t rdev = 0;
 536
 537         if (dentry) {
 538                 name = dentry_name(dentry, 0);
 539                 if (name == NULL)
 540                         goto out;
 541                 type = file_type(name, &maj, &min);
 542                 /* Reencode maj and min with the kernel encoding.*/
 543                 rdev = MKDEV(maj, min);
 544                 kfree(name);
 545         }
 546         else type = OS_TYPE_DIR;
 547
 548         err = 0;
 549         if (type == OS_TYPE_SYMLINK)
 550                 inode->i_op = &page_symlink_inode_operations;
 551         else if (type == OS_TYPE_DIR)
 552                 inode->i_op = &hostfs_dir_iops;
 553         else inode->i_op = &hostfs_iops;
 554
 555         if (type == OS_TYPE_DIR) inode->i_fop = &hostfs_dir_fops;
 556         else inode->i_fop = &hostfs_file_fops;
 557
 558         if (type == OS_TYPE_SYMLINK)
 559                 inode->i_mapping->a_ops = &hostfs_link_aops;
 560         else inode->i_mapping->a_ops = &hostfs_aops;
 561
 562         switch (type) {
 563         case OS_TYPE_CHARDEV:
 564                 init_special_inode(inode, S_IFCHR, rdev);
 565                 break;
 566         case OS_TYPE_BLOCKDEV:
 567                 init_special_inode(inode, S_IFBLK, rdev);
 568                 break;
 569         case OS_TYPE_FIFO:
 570                 init_special_inode(inode, S_IFIFO, 0);
 571                 break;
 572         case OS_TYPE_SOCK:
 573                 init_special_inode(inode, S_IFSOCK, 0);
 574                 break;
 575         }
 576  out:
 577         return err;
 578 }
 579
 580 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode,
 581                   struct nameidata *nd)
 582 {
 583         struct inode *inode;
 584         char *name;
 585         int error, fd;
 586
 587         inode = hostfs_iget(dir->i_sb);
 588         if (IS_ERR(inode)) {
 589                 error = PTR_ERR(inode);
 590                 goto out;
 591         }
 592
 593         error = init_inode(inode, dentry);
 594         if (error)
 595                 goto out_put;
 596
 597         error = -ENOMEM;
 598         name = dentry_name(dentry, 0);
 599         if (name == NULL)
 600                 goto out_put;
 601
 602         fd = file_create(name,
 603                          mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR,
 604                          mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP,
 605                          mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH);
 606         if (fd < 0)
 607                 error = fd;
 608         else error = read_name(inode, name);
 609
 610         kfree(name);
 611         if (error)
 612                 goto out_put;
 613
 614         HOSTFS_I(inode)->fd = fd;
 615         HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE;
 616         d_instantiate(dentry, inode);
 617         return 0;
 618
 619  out_put:
 620         iput(inode);
 621  out:
 622         return error;
 623 }
 624
 625 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry,
 626                              struct nameidata *nd)
 627 {
 628         struct inode *inode;
 629         char *name;
 630         int err;
 631
 632         inode = hostfs_iget(ino->i_sb);
 633         if (IS_ERR(inode)) {
 634                 err = PTR_ERR(inode);
 635                 goto out;
 636         }
 637
 638         err = init_inode(inode, dentry);
 639         if (err)
 640                 goto out_put;
 641
 642         err = -ENOMEM;
 643         name = dentry_name(dentry, 0);
 644         if (name == NULL)
 645                 goto out_put;
 646
 647         err = read_name(inode, name);
 648         kfree(name);
 649         if (err == -ENOENT) {
 650                 iput(inode);
 651                 inode = NULL;
 652         }
 653         else if (err)
 654                 goto out_put;
 655
 656         d_add(dentry, inode);
 657         dentry->d_op = &hostfs_dentry_ops;
 658         return NULL;
 659
 660  out_put:
 661         iput(inode);
 662  out:
 663         return ERR_PTR(err);
 664 }
 665
 666 static char *inode_dentry_name(struct inode *ino, struct dentry *dentry)
 667 {
 668         char *file;
 669         int len;
 670
 671         file = inode_name(ino, dentry->d_name.len + 1);
 672         if (file == NULL)
 673                 return NULL;
 674         strcat(file, "/");
 675         len = strlen(file);
 676         strncat(file, dentry->d_name.name, dentry->d_name.len);
 677         file[len + dentry->d_name.len] = '\0';
 678         return file;
 679 }
 680
 681 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from)
 682 {
 683         char *from_name, *to_name;
 684         int err;
 685
 686         if ((from_name = inode_dentry_name(ino, from)) == NULL)
 687                 return -ENOMEM;
 688         to_name = dentry_name(to, 0);
 689         if (to_name == NULL) {
 690                 kfree(from_name);
 691                 return -ENOMEM;
 692         }
 693         err = link_file(to_name, from_name);
 694         kfree(from_name);
 695         kfree(to_name);
 696         return err;
 697 }
 698
 699 int hostfs_unlink(struct inode *ino, struct dentry *dentry)
 700 {
 701         char *file;
 702         int err;
 703
 704         if ((file = inode_dentry_name(ino, dentry)) == NULL)
 705                 return -ENOMEM;
 706         if (append)
 707                 return -EPERM;
 708
 709         err = unlink_file(file);
 710         kfree(file);
 711         return err;
 712 }
 713
 714 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to)
 715 {
 716         char *file;
 717         int err;
 718
 719         if ((file = inode_dentry_name(ino, dentry)) == NULL)
 720                 return -ENOMEM;
 721         err = make_symlink(file, to);
 722         kfree(file);
 723         return err;
 724 }
 725
 726 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode)
 727 {
 728         char *file;
 729         int err;
 730
 731         if ((file = inode_dentry_name(ino, dentry)) == NULL)
 732                 return -ENOMEM;
 733         err = do_mkdir(file, mode);
 734         kfree(file);
 735         return err;
 736 }
 737
 738 int hostfs_rmdir(struct inode *ino, struct dentry *dentry)
 739 {
 740         char *file;
 741         int err;
 742
 743         if ((file = inode_dentry_name(ino, dentry)) == NULL)
 744                 return -ENOMEM;
 745         err = do_rmdir(file);
 746         kfree(file);
 747         return err;
 748 }
 749
 750 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
 751 {
 752         struct inode *inode;
 753         char *name;
 754         int err;
 755
 756         inode = hostfs_iget(dir->i_sb);
 757         if (IS_ERR(inode)) {
 758                 err = PTR_ERR(inode);
 759                 goto out;
 760         }
 761
 762         err = init_inode(inode, dentry);
 763         if (err)
 764                 goto out_put;
 765
 766         err = -ENOMEM;
 767         name = dentry_name(dentry, 0);
 768         if (name == NULL)
 769                 goto out_put;
 770
 771         init_special_inode(inode, mode, dev);
 772         err = do_mknod(name, mode, MAJOR(dev), MINOR(dev));
 773         if (err)
 774                 goto out_free;
 775
 776         err = read_name(inode, name);
 777         kfree(name);
 778         if (err)
 779                 goto out_put;
 780
 781         d_instantiate(dentry, inode);
 782         return 0;
 783
 784  out_free:
 785         kfree(name);
 786  out_put:
 787         iput(inode);
 788  out:
 789         return err;
 790 }
 791
 792 int hostfs_rename(struct inode *from_ino, struct dentry *from,
 793                   struct inode *to_ino, struct dentry *to)
 794 {
 795         char *from_name, *to_name;
 796         int err;
 797
 798         if ((from_name = inode_dentry_name(from_ino, from)) == NULL)
 799                 return -ENOMEM;
 800         if ((to_name = inode_dentry_name(to_ino, to)) == NULL) {
 801                 kfree(from_name);
 802                 return -ENOMEM;
 803         }
 804         err = rename_file(from_name, to_name);
 805         kfree(from_name);
 806         kfree(to_name);
 807         return err;
 808 }
 809
 810 int hostfs_permission(struct inode *ino, int desired, struct nameidata *nd)
 811 {
 812         char *name;
 813         int r = 0, w = 0, x = 0, err;
 814
 815         if (desired & MAY_READ) r = 1;
 816         if (desired & MAY_WRITE) w = 1;
 817         if (desired & MAY_EXEC) x = 1;
 818         name = inode_name(ino, 0);
 819         if (name == NULL)
 820                 return -ENOMEM;
 821
 822         if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) ||
 823             S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode))
 824                 err = 0;
 825         else
 826                 err = access_file(name, r, w, x);
 827         kfree(name);
 828         if (!err)
 829                 err = generic_permission(ino, desired, NULL);
 830         return err;
 831 }
 832
 833 int hostfs_setattr(struct dentry *dentry, struct iattr *attr)
 834 {
 835         struct hostfs_iattr attrs;
 836         char *name;
 837         int err;
 838
 839         int fd = HOSTFS_I(dentry->d_inode)->fd;
 840
 841         err = inode_change_ok(dentry->d_inode, attr);
 842         if (err)
 843                 return err;
 844
 845         if (append)
 846                 attr->ia_valid &= ~ATTR_SIZE;
 847
 848         attrs.ia_valid = 0;
 849         if (attr->ia_valid & ATTR_MODE) {
 850                 attrs.ia_valid |= HOSTFS_ATTR_MODE;
 851                 attrs.ia_mode = attr->ia_mode;
 852         }
 853         if (attr->ia_valid & ATTR_UID) {
 854                 attrs.ia_valid |= HOSTFS_ATTR_UID;
 855                 attrs.ia_uid = attr->ia_uid;
 856         }
 857         if (attr->ia_valid & ATTR_GID) {
 858                 attrs.ia_valid |= HOSTFS_ATTR_GID;
 859                 attrs.ia_gid = attr->ia_gid;
 860         }
 861         if (attr->ia_valid & ATTR_SIZE) {
 862                 attrs.ia_valid |= HOSTFS_ATTR_SIZE;
 863                 attrs.ia_size = attr->ia_size;
 864         }
 865         if (attr->ia_valid & ATTR_ATIME) {
 866                 attrs.ia_valid |= HOSTFS_ATTR_ATIME;
 867                 attrs.ia_atime = attr->ia_atime;
 868         }
 869         if (attr->ia_valid & ATTR_MTIME) {
 870                 attrs.ia_valid |= HOSTFS_ATTR_MTIME;
 871                 attrs.ia_mtime = attr->ia_mtime;
 872         }
 873         if (attr->ia_valid & ATTR_CTIME) {
 874                 attrs.ia_valid |= HOSTFS_ATTR_CTIME;
 875                 attrs.ia_ctime = attr->ia_ctime;
 876         }
 877         if (attr->ia_valid & ATTR_ATIME_SET) {
 878                 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET;
 879         }
 880         if (attr->ia_valid & ATTR_MTIME_SET) {
 881                 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET;
 882         }
 883         name = dentry_name(dentry, 0);
 884         if (name == NULL)
 885                 return -ENOMEM;
 886         err = set_attr(name, &attrs, fd);
 887         kfree(name);
 888         if (err)
 889                 return err;
 890
 891         return inode_setattr(dentry->d_inode, attr);
 892 }
 893
 894 static const struct inode_operations hostfs_iops = {
 895         .create         = hostfs_create,
 896         .link           = hostfs_link,
 897         .unlink         = hostfs_unlink,
 898         .symlink        = hostfs_symlink,
 899         .mkdir          = hostfs_mkdir,
 900         .rmdir          = hostfs_rmdir,
 901         .mknod          = hostfs_mknod,
 902         .rename         = hostfs_rename,
 903         .permission     = hostfs_permission,
 904         .setattr        = hostfs_setattr,
 905 };
 906
 907 static const struct inode_operations hostfs_dir_iops = {
 908         .create         = hostfs_create,
 909         .lookup         = hostfs_lookup,
 910         .link           = hostfs_link,
 911         .unlink         = hostfs_unlink,
 912         .symlink        = hostfs_symlink,
 913         .mkdir          = hostfs_mkdir,
 914         .rmdir          = hostfs_rmdir,
 915         .mknod          = hostfs_mknod,
 916         .rename         = hostfs_rename,
 917         .permission     = hostfs_permission,
 918         .setattr        = hostfs_setattr,
 919 };
 920
 921 int hostfs_link_readpage(struct file *file, struct page *page)
 922 {
 923         char *buffer, *name;
 924         int err;
 925
 926         buffer = kmap(page);
 927         name = inode_name(page->mapping->host, 0);
 928         if (name == NULL)
 929                 return -ENOMEM;
 930         err = do_readlink(name, buffer, PAGE_CACHE_SIZE);
 931         kfree(name);
 932         if (err == PAGE_CACHE_SIZE)
 933                 err = -E2BIG;
 934         else if (err > 0) {
 935                 flush_dcache_page(page);
 936                 SetPageUptodate(page);
 937                 if (PageError(page)) ClearPageError(page);
 938                 err = 0;
 939         }
 940         kunmap(page);
 941         unlock_page(page);
 942         return err;
 943 }
 944
 945 static const struct address_space_operations hostfs_link_aops = {
 946         .readpage       = hostfs_link_readpage,
 947 };
 948
 949 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent)
 950 {
 951         struct inode *root_inode;
 952         char *host_root_path, *req_root = d;
 953         int err;
 954
 955         sb->s_blocksize = 1024;
 956         sb->s_blocksize_bits = 10;
 957         sb->s_magic = HOSTFS_SUPER_MAGIC;
 958         sb->s_op = &hostfs_sbops;
 959
 960         /* NULL is printed as <NULL> by sprintf: avoid that. */
 961         if (req_root == NULL)
 962                 req_root = "";
 963
 964         err = -ENOMEM;
 965         host_root_path = kmalloc(strlen(root_ino) + 1
 966                                  + strlen(req_root) + 1, GFP_KERNEL);
 967         if (host_root_path == NULL)
 968                 goto out;
 969
 970         sprintf(host_root_path, "%s/%s", root_ino, req_root);
 971
 972         root_inode = hostfs_iget(sb);
 973         if (IS_ERR(root_inode)) {
 974                 err = PTR_ERR(root_inode);
 975                 goto out_free;
 976         }
 977
 978         err = init_inode(root_inode, NULL);
 979         if (err)
 980                 goto out_put;
 981
 982         HOSTFS_I(root_inode)->host_filename = host_root_path;
 983         /*
 984          * Avoid that in the error path, iput(root_inode) frees again
 985          * host_root_path through hostfs_destroy_inode!
 986          */
 987         host_root_path = NULL;
 988
 989         err = -ENOMEM;
 990         sb->s_root = d_alloc_root(root_inode);
 991         if (sb->s_root == NULL)
 992                 goto out_put;
 993
 994         err = hostfs_read_inode(root_inode);
 995         if (err) {
 996                 /* No iput in this case because the dput does that for us */
 997                 dput(sb->s_root);
 998                 sb->s_root = NULL;
 999                 goto out;
1000         }
1001
1002         return 0;
1003
1004 out_put:
1005         iput(root_inode);
1006 out_free:
1007         kfree(host_root_path);
1008 out:
1009         return err;
1010 }
1011
1012 static int hostfs_read_sb(struct file_system_type *type,
1013                           int flags, const char *dev_name,
1014                           void *data, struct vfsmount *mnt)
1015 {
1016         return get_sb_nodev(type, flags, data, hostfs_fill_sb_common, mnt);
1017 }
1018
1019 static struct file_system_type hostfs_type = {
1020         .owner          = THIS_MODULE,
1021         .name           = "hostfs",
1022         .get_sb         = hostfs_read_sb,
1023         .kill_sb        = kill_anon_super,
1024         .fs_flags       = 0,
1025 };
1026
1027 static int __init init_hostfs(void)
1028 {
1029         return register_filesystem(&hostfs_type);
1030 }
1031
1032 static void __exit exit_hostfs(void)
1033 {
1034         unregister_filesystem(&hostfs_type);
1035 }
1036
1037 module_init(init_hostfs)
1038 module_exit(exit_hostfs)
1039 MODULE_LICENSE("GPL");