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/magic.h> 11 #include <linux/module.h> 12 #include <linux/mm.h> 13 #include <linux/pagemap.h> 14 #include <linux/statfs.h> 15 #include <linux/slab.h> 16 #include <linux/seq_file.h> 17 #include <linux/mount.h> 18 #include <linux/namei.h> 19 #include "hostfs.h" 20 #include <init.h> 21 #include <kern.h> 22 23 struct hostfs_inode_info { 24 int fd; 25 fmode_t mode; 26 struct inode vfs_inode; 27 struct mutex open_mutex; 28 }; 29 30 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 31 { 32 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 33 } 34 35 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 36 37 /* Changed in hostfs_args before the kernel starts running */ 38 static char *root_ino = ""; 39 static int append = 0; 40 41 static const struct inode_operations hostfs_iops; 42 static const struct inode_operations hostfs_dir_iops; 43 static const struct inode_operations hostfs_link_iops; 44 45 #ifndef MODULE 46 static int __init hostfs_args(char *options, int *add) 47 { 48 char *ptr; 49 50 ptr = strchr(options, ','); 51 if (ptr != NULL) 52 *ptr++ = '\0'; 53 if (*options != '\0') 54 root_ino = options; 55 56 options = ptr; 57 while (options) { 58 ptr = strchr(options, ','); 59 if (ptr != NULL) 60 *ptr++ = '\0'; 61 if (*options != '\0') { 62 if (!strcmp(options, "append")) 63 append = 1; 64 else printf("hostfs_args - unsupported option - %s\n", 65 options); 66 } 67 options = ptr; 68 } 69 return 0; 70 } 71 72 __uml_setup("hostfs=", hostfs_args, 73 "hostfs=<root dir>,<flags>,...\n" 74 " This is used to set hostfs parameters. The root directory argument\n" 75 " is used to confine all hostfs mounts to within the specified directory\n" 76 " tree on the host. If this isn't specified, then a user inside UML can\n" 77 " mount anything on the host that's accessible to the user that's running\n" 78 " it.\n" 79 " The only flag currently supported is 'append', which specifies that all\n" 80 " files opened by hostfs will be opened in append mode.\n\n" 81 ); 82 #endif 83 84 static char *__dentry_name(struct dentry *dentry, char *name) 85 { 86 char *p = dentry_path_raw(dentry, name, PATH_MAX); 87 char *root; 88 size_t len; 89 90 root = dentry->d_sb->s_fs_info; 91 len = strlen(root); 92 if (IS_ERR(p)) { 93 __putname(name); 94 return NULL; 95 } 96 97 /* 98 * This function relies on the fact that dentry_path_raw() will place 99 * the path name at the end of the provided buffer. 100 */ 101 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX); 102 103 strlcpy(name, root, PATH_MAX); 104 if (len > p - name) { 105 __putname(name); 106 return NULL; 107 } 108 109 if (p > name + len) 110 strcpy(name + len, p); 111 112 return name; 113 } 114 115 static char *dentry_name(struct dentry *dentry) 116 { 117 char *name = __getname(); 118 if (!name) 119 return NULL; 120 121 return __dentry_name(dentry, name); 122 } 123 124 static char *inode_name(struct inode *ino) 125 { 126 struct dentry *dentry; 127 char *name; 128 129 dentry = d_find_alias(ino); 130 if (!dentry) 131 return NULL; 132 133 name = dentry_name(dentry); 134 135 dput(dentry); 136 137 return name; 138 } 139 140 static char *follow_link(char *link) 141 { 142 int len, n; 143 char *name, *resolved, *end; 144 145 name = __getname(); 146 if (!name) { 147 n = -ENOMEM; 148 goto out_free; 149 } 150 151 n = hostfs_do_readlink(link, name, PATH_MAX); 152 if (n < 0) 153 goto out_free; 154 else if (n == PATH_MAX) { 155 n = -E2BIG; 156 goto out_free; 157 } 158 159 if (*name == '/') 160 return name; 161 162 end = strrchr(link, '/'); 163 if (end == NULL) 164 return name; 165 166 *(end + 1) = '\0'; 167 len = strlen(link) + strlen(name) + 1; 168 169 resolved = kmalloc(len, GFP_KERNEL); 170 if (resolved == NULL) { 171 n = -ENOMEM; 172 goto out_free; 173 } 174 175 sprintf(resolved, "%s%s", link, name); 176 __putname(name); 177 kfree(link); 178 return resolved; 179 180 out_free: 181 __putname(name); 182 return ERR_PTR(n); 183 } 184 185 static struct inode *hostfs_iget(struct super_block *sb) 186 { 187 struct inode *inode = new_inode(sb); 188 if (!inode) 189 return ERR_PTR(-ENOMEM); 190 return inode; 191 } 192 193 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 194 { 195 /* 196 * do_statfs uses struct statfs64 internally, but the linux kernel 197 * struct statfs still has 32-bit versions for most of these fields, 198 * so we convert them here 199 */ 200 int err; 201 long long f_blocks; 202 long long f_bfree; 203 long long f_bavail; 204 long long f_files; 205 long long f_ffree; 206 207 err = do_statfs(dentry->d_sb->s_fs_info, 208 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 209 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 210 &sf->f_namelen); 211 if (err) 212 return err; 213 sf->f_blocks = f_blocks; 214 sf->f_bfree = f_bfree; 215 sf->f_bavail = f_bavail; 216 sf->f_files = f_files; 217 sf->f_ffree = f_ffree; 218 sf->f_type = HOSTFS_SUPER_MAGIC; 219 return 0; 220 } 221 222 static struct inode *hostfs_alloc_inode(struct super_block *sb) 223 { 224 struct hostfs_inode_info *hi; 225 226 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 227 if (hi == NULL) 228 return NULL; 229 hi->fd = -1; 230 hi->mode = 0; 231 inode_init_once(&hi->vfs_inode); 232 mutex_init(&hi->open_mutex); 233 return &hi->vfs_inode; 234 } 235 236 static void hostfs_evict_inode(struct inode *inode) 237 { 238 truncate_inode_pages_final(&inode->i_data); 239 clear_inode(inode); 240 if (HOSTFS_I(inode)->fd != -1) { 241 close_file(&HOSTFS_I(inode)->fd); 242 HOSTFS_I(inode)->fd = -1; 243 } 244 } 245 246 static void hostfs_i_callback(struct rcu_head *head) 247 { 248 struct inode *inode = container_of(head, struct inode, i_rcu); 249 kfree(HOSTFS_I(inode)); 250 } 251 252 static void hostfs_destroy_inode(struct inode *inode) 253 { 254 call_rcu(&inode->i_rcu, hostfs_i_callback); 255 } 256 257 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 258 { 259 const char *root_path = root->d_sb->s_fs_info; 260 size_t offset = strlen(root_ino) + 1; 261 262 if (strlen(root_path) > offset) 263 seq_printf(seq, ",%s", root_path + offset); 264 265 if (append) 266 seq_puts(seq, ",append"); 267 268 return 0; 269 } 270 271 static const struct super_operations hostfs_sbops = { 272 .alloc_inode = hostfs_alloc_inode, 273 .destroy_inode = hostfs_destroy_inode, 274 .evict_inode = hostfs_evict_inode, 275 .statfs = hostfs_statfs, 276 .show_options = hostfs_show_options, 277 }; 278 279 static int hostfs_readdir(struct file *file, struct dir_context *ctx) 280 { 281 void *dir; 282 char *name; 283 unsigned long long next, ino; 284 int error, len; 285 unsigned int type; 286 287 name = dentry_name(file->f_path.dentry); 288 if (name == NULL) 289 return -ENOMEM; 290 dir = open_dir(name, &error); 291 __putname(name); 292 if (dir == NULL) 293 return -error; 294 next = ctx->pos; 295 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 296 if (!dir_emit(ctx, name, len, ino, type)) 297 break; 298 ctx->pos = next; 299 } 300 close_dir(dir); 301 return 0; 302 } 303 304 static int hostfs_open(struct inode *ino, struct file *file) 305 { 306 char *name; 307 fmode_t mode; 308 int err; 309 int r, w, fd; 310 311 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 312 if ((mode & HOSTFS_I(ino)->mode) == mode) 313 return 0; 314 315 mode |= HOSTFS_I(ino)->mode; 316 317 retry: 318 r = w = 0; 319 320 if (mode & FMODE_READ) 321 r = 1; 322 if (mode & FMODE_WRITE) 323 r = w = 1; 324 325 name = dentry_name(file->f_path.dentry); 326 if (name == NULL) 327 return -ENOMEM; 328 329 fd = open_file(name, r, w, append); 330 __putname(name); 331 if (fd < 0) 332 return fd; 333 334 mutex_lock(&HOSTFS_I(ino)->open_mutex); 335 /* somebody else had handled it first? */ 336 if ((mode & HOSTFS_I(ino)->mode) == mode) { 337 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 338 close_file(&fd); 339 return 0; 340 } 341 if ((mode | HOSTFS_I(ino)->mode) != mode) { 342 mode |= HOSTFS_I(ino)->mode; 343 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 344 close_file(&fd); 345 goto retry; 346 } 347 if (HOSTFS_I(ino)->fd == -1) { 348 HOSTFS_I(ino)->fd = fd; 349 } else { 350 err = replace_file(fd, HOSTFS_I(ino)->fd); 351 close_file(&fd); 352 if (err < 0) { 353 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 354 return err; 355 } 356 } 357 HOSTFS_I(ino)->mode = mode; 358 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 359 360 return 0; 361 } 362 363 static int hostfs_file_release(struct inode *inode, struct file *file) 364 { 365 filemap_write_and_wait(inode->i_mapping); 366 367 return 0; 368 } 369 370 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 371 int datasync) 372 { 373 struct inode *inode = file->f_mapping->host; 374 int ret; 375 376 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 377 if (ret) 378 return ret; 379 380 mutex_lock(&inode->i_mutex); 381 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 382 mutex_unlock(&inode->i_mutex); 383 384 return ret; 385 } 386 387 static const struct file_operations hostfs_file_fops = { 388 .llseek = generic_file_llseek, 389 .read = new_sync_read, 390 .splice_read = generic_file_splice_read, 391 .read_iter = generic_file_read_iter, 392 .write_iter = generic_file_write_iter, 393 .write = new_sync_write, 394 .mmap = generic_file_mmap, 395 .open = hostfs_open, 396 .release = hostfs_file_release, 397 .fsync = hostfs_fsync, 398 }; 399 400 static const struct file_operations hostfs_dir_fops = { 401 .llseek = generic_file_llseek, 402 .iterate = hostfs_readdir, 403 .read = generic_read_dir, 404 .open = hostfs_open, 405 .fsync = hostfs_fsync, 406 }; 407 408 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 409 { 410 struct address_space *mapping = page->mapping; 411 struct inode *inode = mapping->host; 412 char *buffer; 413 loff_t base = page_offset(page); 414 int count = PAGE_CACHE_SIZE; 415 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 416 int err; 417 418 if (page->index >= end_index) 419 count = inode->i_size & (PAGE_CACHE_SIZE-1); 420 421 buffer = kmap(page); 422 423 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 424 if (err != count) { 425 ClearPageUptodate(page); 426 goto out; 427 } 428 429 if (base > inode->i_size) 430 inode->i_size = base; 431 432 if (PageError(page)) 433 ClearPageError(page); 434 err = 0; 435 436 out: 437 kunmap(page); 438 439 unlock_page(page); 440 return err; 441 } 442 443 static int hostfs_readpage(struct file *file, struct page *page) 444 { 445 char *buffer; 446 loff_t start = page_offset(page); 447 int bytes_read, ret = 0; 448 449 buffer = kmap(page); 450 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 451 PAGE_CACHE_SIZE); 452 if (bytes_read < 0) { 453 ClearPageUptodate(page); 454 SetPageError(page); 455 ret = bytes_read; 456 goto out; 457 } 458 459 memset(buffer + bytes_read, 0, PAGE_CACHE_SIZE - bytes_read); 460 461 ClearPageError(page); 462 SetPageUptodate(page); 463 464 out: 465 flush_dcache_page(page); 466 kunmap(page); 467 unlock_page(page); 468 return ret; 469 } 470 471 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 472 loff_t pos, unsigned len, unsigned flags, 473 struct page **pagep, void **fsdata) 474 { 475 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 476 477 *pagep = grab_cache_page_write_begin(mapping, index, flags); 478 if (!*pagep) 479 return -ENOMEM; 480 return 0; 481 } 482 483 static int hostfs_write_end(struct file *file, struct address_space *mapping, 484 loff_t pos, unsigned len, unsigned copied, 485 struct page *page, void *fsdata) 486 { 487 struct inode *inode = mapping->host; 488 void *buffer; 489 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 490 int err; 491 492 buffer = kmap(page); 493 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 494 kunmap(page); 495 496 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 497 SetPageUptodate(page); 498 499 /* 500 * If err > 0, write_file has added err to pos, so we are comparing 501 * i_size against the last byte written. 502 */ 503 if (err > 0 && (pos > inode->i_size)) 504 inode->i_size = pos; 505 unlock_page(page); 506 page_cache_release(page); 507 508 return err; 509 } 510 511 static const struct address_space_operations hostfs_aops = { 512 .writepage = hostfs_writepage, 513 .readpage = hostfs_readpage, 514 .set_page_dirty = __set_page_dirty_nobuffers, 515 .write_begin = hostfs_write_begin, 516 .write_end = hostfs_write_end, 517 }; 518 519 static int read_name(struct inode *ino, char *name) 520 { 521 dev_t rdev; 522 struct hostfs_stat st; 523 int err = stat_file(name, &st, -1); 524 if (err) 525 return err; 526 527 /* Reencode maj and min with the kernel encoding.*/ 528 rdev = MKDEV(st.maj, st.min); 529 530 switch (st.mode & S_IFMT) { 531 case S_IFLNK: 532 ino->i_op = &hostfs_link_iops; 533 break; 534 case S_IFDIR: 535 ino->i_op = &hostfs_dir_iops; 536 ino->i_fop = &hostfs_dir_fops; 537 break; 538 case S_IFCHR: 539 case S_IFBLK: 540 case S_IFIFO: 541 case S_IFSOCK: 542 init_special_inode(ino, st.mode & S_IFMT, rdev); 543 ino->i_op = &hostfs_iops; 544 break; 545 case S_IFREG: 546 ino->i_op = &hostfs_iops; 547 ino->i_fop = &hostfs_file_fops; 548 ino->i_mapping->a_ops = &hostfs_aops; 549 break; 550 default: 551 return -EIO; 552 } 553 554 ino->i_ino = st.ino; 555 ino->i_mode = st.mode; 556 set_nlink(ino, st.nlink); 557 i_uid_write(ino, st.uid); 558 i_gid_write(ino, st.gid); 559 ino->i_atime = st.atime; 560 ino->i_mtime = st.mtime; 561 ino->i_ctime = st.ctime; 562 ino->i_size = st.size; 563 ino->i_blocks = st.blocks; 564 return 0; 565 } 566 567 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 568 bool excl) 569 { 570 struct inode *inode; 571 char *name; 572 int error, fd; 573 574 inode = hostfs_iget(dir->i_sb); 575 if (IS_ERR(inode)) { 576 error = PTR_ERR(inode); 577 goto out; 578 } 579 580 error = -ENOMEM; 581 name = dentry_name(dentry); 582 if (name == NULL) 583 goto out_put; 584 585 fd = file_create(name, mode & S_IFMT); 586 if (fd < 0) 587 error = fd; 588 else 589 error = read_name(inode, name); 590 591 __putname(name); 592 if (error) 593 goto out_put; 594 595 HOSTFS_I(inode)->fd = fd; 596 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 597 d_instantiate(dentry, inode); 598 return 0; 599 600 out_put: 601 iput(inode); 602 out: 603 return error; 604 } 605 606 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 607 unsigned int flags) 608 { 609 struct inode *inode; 610 char *name; 611 int err; 612 613 inode = hostfs_iget(ino->i_sb); 614 if (IS_ERR(inode)) { 615 err = PTR_ERR(inode); 616 goto out; 617 } 618 619 err = -ENOMEM; 620 name = dentry_name(dentry); 621 if (name == NULL) 622 goto out_put; 623 624 err = read_name(inode, name); 625 626 __putname(name); 627 if (err == -ENOENT) { 628 iput(inode); 629 inode = NULL; 630 } 631 else if (err) 632 goto out_put; 633 634 d_add(dentry, inode); 635 return NULL; 636 637 out_put: 638 iput(inode); 639 out: 640 return ERR_PTR(err); 641 } 642 643 static int hostfs_link(struct dentry *to, struct inode *ino, 644 struct dentry *from) 645 { 646 char *from_name, *to_name; 647 int err; 648 649 if ((from_name = dentry_name(from)) == NULL) 650 return -ENOMEM; 651 to_name = dentry_name(to); 652 if (to_name == NULL) { 653 __putname(from_name); 654 return -ENOMEM; 655 } 656 err = link_file(to_name, from_name); 657 __putname(from_name); 658 __putname(to_name); 659 return err; 660 } 661 662 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 663 { 664 char *file; 665 int err; 666 667 if (append) 668 return -EPERM; 669 670 if ((file = dentry_name(dentry)) == NULL) 671 return -ENOMEM; 672 673 err = unlink_file(file); 674 __putname(file); 675 return err; 676 } 677 678 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 679 const char *to) 680 { 681 char *file; 682 int err; 683 684 if ((file = dentry_name(dentry)) == NULL) 685 return -ENOMEM; 686 err = make_symlink(file, to); 687 __putname(file); 688 return err; 689 } 690 691 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 692 { 693 char *file; 694 int err; 695 696 if ((file = dentry_name(dentry)) == NULL) 697 return -ENOMEM; 698 err = do_mkdir(file, mode); 699 __putname(file); 700 return err; 701 } 702 703 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 704 { 705 char *file; 706 int err; 707 708 if ((file = dentry_name(dentry)) == NULL) 709 return -ENOMEM; 710 err = do_rmdir(file); 711 __putname(file); 712 return err; 713 } 714 715 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 716 { 717 struct inode *inode; 718 char *name; 719 int err; 720 721 inode = hostfs_iget(dir->i_sb); 722 if (IS_ERR(inode)) { 723 err = PTR_ERR(inode); 724 goto out; 725 } 726 727 err = -ENOMEM; 728 name = dentry_name(dentry); 729 if (name == NULL) 730 goto out_put; 731 732 init_special_inode(inode, mode, dev); 733 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 734 if (!err) 735 goto out_free; 736 737 err = read_name(inode, name); 738 __putname(name); 739 if (err) 740 goto out_put; 741 if (err) 742 goto out_put; 743 744 d_instantiate(dentry, inode); 745 return 0; 746 747 out_free: 748 __putname(name); 749 out_put: 750 iput(inode); 751 out: 752 return err; 753 } 754 755 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 756 struct inode *new_dir, struct dentry *new_dentry, 757 unsigned int flags) 758 { 759 char *old_name, *new_name; 760 int err; 761 762 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 763 return -EINVAL; 764 765 old_name = dentry_name(old_dentry); 766 if (old_name == NULL) 767 return -ENOMEM; 768 new_name = dentry_name(new_dentry); 769 if (new_name == NULL) { 770 __putname(old_name); 771 return -ENOMEM; 772 } 773 if (!flags) 774 err = rename_file(old_name, new_name); 775 else 776 err = rename2_file(old_name, new_name, flags); 777 778 __putname(old_name); 779 __putname(new_name); 780 return err; 781 } 782 783 static int hostfs_permission(struct inode *ino, int desired) 784 { 785 char *name; 786 int r = 0, w = 0, x = 0, err; 787 788 if (desired & MAY_NOT_BLOCK) 789 return -ECHILD; 790 791 if (desired & MAY_READ) r = 1; 792 if (desired & MAY_WRITE) w = 1; 793 if (desired & MAY_EXEC) x = 1; 794 name = inode_name(ino); 795 if (name == NULL) 796 return -ENOMEM; 797 798 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 799 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 800 err = 0; 801 else 802 err = access_file(name, r, w, x); 803 __putname(name); 804 if (!err) 805 err = generic_permission(ino, desired); 806 return err; 807 } 808 809 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 810 { 811 struct inode *inode = dentry->d_inode; 812 struct hostfs_iattr attrs; 813 char *name; 814 int err; 815 816 int fd = HOSTFS_I(inode)->fd; 817 818 err = inode_change_ok(inode, attr); 819 if (err) 820 return err; 821 822 if (append) 823 attr->ia_valid &= ~ATTR_SIZE; 824 825 attrs.ia_valid = 0; 826 if (attr->ia_valid & ATTR_MODE) { 827 attrs.ia_valid |= HOSTFS_ATTR_MODE; 828 attrs.ia_mode = attr->ia_mode; 829 } 830 if (attr->ia_valid & ATTR_UID) { 831 attrs.ia_valid |= HOSTFS_ATTR_UID; 832 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 833 } 834 if (attr->ia_valid & ATTR_GID) { 835 attrs.ia_valid |= HOSTFS_ATTR_GID; 836 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 837 } 838 if (attr->ia_valid & ATTR_SIZE) { 839 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 840 attrs.ia_size = attr->ia_size; 841 } 842 if (attr->ia_valid & ATTR_ATIME) { 843 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 844 attrs.ia_atime = attr->ia_atime; 845 } 846 if (attr->ia_valid & ATTR_MTIME) { 847 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 848 attrs.ia_mtime = attr->ia_mtime; 849 } 850 if (attr->ia_valid & ATTR_CTIME) { 851 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 852 attrs.ia_ctime = attr->ia_ctime; 853 } 854 if (attr->ia_valid & ATTR_ATIME_SET) { 855 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 856 } 857 if (attr->ia_valid & ATTR_MTIME_SET) { 858 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 859 } 860 name = dentry_name(dentry); 861 if (name == NULL) 862 return -ENOMEM; 863 err = set_attr(name, &attrs, fd); 864 __putname(name); 865 if (err) 866 return err; 867 868 if ((attr->ia_valid & ATTR_SIZE) && 869 attr->ia_size != i_size_read(inode)) 870 truncate_setsize(inode, attr->ia_size); 871 872 setattr_copy(inode, attr); 873 mark_inode_dirty(inode); 874 return 0; 875 } 876 877 static const struct inode_operations hostfs_iops = { 878 .permission = hostfs_permission, 879 .setattr = hostfs_setattr, 880 }; 881 882 static const struct inode_operations hostfs_dir_iops = { 883 .create = hostfs_create, 884 .lookup = hostfs_lookup, 885 .link = hostfs_link, 886 .unlink = hostfs_unlink, 887 .symlink = hostfs_symlink, 888 .mkdir = hostfs_mkdir, 889 .rmdir = hostfs_rmdir, 890 .mknod = hostfs_mknod, 891 .rename2 = hostfs_rename2, 892 .permission = hostfs_permission, 893 .setattr = hostfs_setattr, 894 }; 895 896 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 897 { 898 char *link = __getname(); 899 if (link) { 900 char *path = dentry_name(dentry); 901 int err = -ENOMEM; 902 if (path) { 903 err = hostfs_do_readlink(path, link, PATH_MAX); 904 if (err == PATH_MAX) 905 err = -E2BIG; 906 __putname(path); 907 } 908 if (err < 0) { 909 __putname(link); 910 link = ERR_PTR(err); 911 } 912 } else { 913 link = ERR_PTR(-ENOMEM); 914 } 915 916 nd_set_link(nd, link); 917 return NULL; 918 } 919 920 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 921 { 922 char *s = nd_get_link(nd); 923 if (!IS_ERR(s)) 924 __putname(s); 925 } 926 927 static const struct inode_operations hostfs_link_iops = { 928 .readlink = generic_readlink, 929 .follow_link = hostfs_follow_link, 930 .put_link = hostfs_put_link, 931 }; 932 933 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 934 { 935 struct inode *root_inode; 936 char *host_root_path, *req_root = d; 937 int err; 938 939 sb->s_blocksize = 1024; 940 sb->s_blocksize_bits = 10; 941 sb->s_magic = HOSTFS_SUPER_MAGIC; 942 sb->s_op = &hostfs_sbops; 943 sb->s_d_op = &simple_dentry_operations; 944 sb->s_maxbytes = MAX_LFS_FILESIZE; 945 946 /* NULL is printed as <NULL> by sprintf: avoid that. */ 947 if (req_root == NULL) 948 req_root = ""; 949 950 err = -ENOMEM; 951 sb->s_fs_info = host_root_path = 952 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 953 if (host_root_path == NULL) 954 goto out; 955 956 sprintf(host_root_path, "%s/%s", root_ino, req_root); 957 958 root_inode = new_inode(sb); 959 if (!root_inode) 960 goto out; 961 962 err = read_name(root_inode, host_root_path); 963 if (err) 964 goto out_put; 965 966 if (S_ISLNK(root_inode->i_mode)) { 967 char *name = follow_link(host_root_path); 968 if (IS_ERR(name)) 969 err = PTR_ERR(name); 970 else 971 err = read_name(root_inode, name); 972 kfree(name); 973 if (err) 974 goto out_put; 975 } 976 977 err = -ENOMEM; 978 sb->s_root = d_make_root(root_inode); 979 if (sb->s_root == NULL) 980 goto out; 981 982 return 0; 983 984 out_put: 985 iput(root_inode); 986 out: 987 return err; 988 } 989 990 static struct dentry *hostfs_read_sb(struct file_system_type *type, 991 int flags, const char *dev_name, 992 void *data) 993 { 994 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 995 } 996 997 static void hostfs_kill_sb(struct super_block *s) 998 { 999 kill_anon_super(s); 1000 kfree(s->s_fs_info); 1001 } 1002 1003 static struct file_system_type hostfs_type = { 1004 .owner = THIS_MODULE, 1005 .name = "hostfs", 1006 .mount = hostfs_read_sb, 1007 .kill_sb = hostfs_kill_sb, 1008 .fs_flags = 0, 1009 }; 1010 MODULE_ALIAS_FS("hostfs"); 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