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 char *name, *resolved, *end; 143 int n; 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'; 167 168 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name); 169 if (resolved == NULL) { 170 n = -ENOMEM; 171 goto out_free; 172 } 173 174 __putname(name); 175 kfree(link); 176 return resolved; 177 178 out_free: 179 __putname(name); 180 return ERR_PTR(n); 181 } 182 183 static struct inode *hostfs_iget(struct super_block *sb) 184 { 185 struct inode *inode = new_inode(sb); 186 if (!inode) 187 return ERR_PTR(-ENOMEM); 188 return inode; 189 } 190 191 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 192 { 193 /* 194 * do_statfs uses struct statfs64 internally, but the linux kernel 195 * struct statfs still has 32-bit versions for most of these fields, 196 * so we convert them here 197 */ 198 int err; 199 long long f_blocks; 200 long long f_bfree; 201 long long f_bavail; 202 long long f_files; 203 long long f_ffree; 204 205 err = do_statfs(dentry->d_sb->s_fs_info, 206 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 207 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 208 &sf->f_namelen); 209 if (err) 210 return err; 211 sf->f_blocks = f_blocks; 212 sf->f_bfree = f_bfree; 213 sf->f_bavail = f_bavail; 214 sf->f_files = f_files; 215 sf->f_ffree = f_ffree; 216 sf->f_type = HOSTFS_SUPER_MAGIC; 217 return 0; 218 } 219 220 static struct inode *hostfs_alloc_inode(struct super_block *sb) 221 { 222 struct hostfs_inode_info *hi; 223 224 hi = kmalloc(sizeof(*hi), GFP_KERNEL_ACCOUNT); 225 if (hi == NULL) 226 return NULL; 227 hi->fd = -1; 228 hi->mode = 0; 229 inode_init_once(&hi->vfs_inode); 230 mutex_init(&hi->open_mutex); 231 return &hi->vfs_inode; 232 } 233 234 static void hostfs_evict_inode(struct inode *inode) 235 { 236 truncate_inode_pages_final(&inode->i_data); 237 clear_inode(inode); 238 if (HOSTFS_I(inode)->fd != -1) { 239 close_file(&HOSTFS_I(inode)->fd); 240 HOSTFS_I(inode)->fd = -1; 241 } 242 } 243 244 static void hostfs_free_inode(struct inode *inode) 245 { 246 kfree(HOSTFS_I(inode)); 247 } 248 249 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 250 { 251 const char *root_path = root->d_sb->s_fs_info; 252 size_t offset = strlen(root_ino) + 1; 253 254 if (strlen(root_path) > offset) 255 seq_show_option(seq, root_path + offset, NULL); 256 257 if (append) 258 seq_puts(seq, ",append"); 259 260 return 0; 261 } 262 263 static const struct super_operations hostfs_sbops = { 264 .alloc_inode = hostfs_alloc_inode, 265 .free_inode = hostfs_free_inode, 266 .evict_inode = hostfs_evict_inode, 267 .statfs = hostfs_statfs, 268 .show_options = hostfs_show_options, 269 }; 270 271 static int hostfs_readdir(struct file *file, struct dir_context *ctx) 272 { 273 void *dir; 274 char *name; 275 unsigned long long next, ino; 276 int error, len; 277 unsigned int type; 278 279 name = dentry_name(file->f_path.dentry); 280 if (name == NULL) 281 return -ENOMEM; 282 dir = open_dir(name, &error); 283 __putname(name); 284 if (dir == NULL) 285 return -error; 286 next = ctx->pos; 287 seek_dir(dir, next); 288 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 289 if (!dir_emit(ctx, name, len, ino, type)) 290 break; 291 ctx->pos = next; 292 } 293 close_dir(dir); 294 return 0; 295 } 296 297 static int hostfs_open(struct inode *ino, struct file *file) 298 { 299 char *name; 300 fmode_t mode; 301 int err; 302 int r, w, fd; 303 304 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 305 if ((mode & HOSTFS_I(ino)->mode) == mode) 306 return 0; 307 308 mode |= HOSTFS_I(ino)->mode; 309 310 retry: 311 r = w = 0; 312 313 if (mode & FMODE_READ) 314 r = 1; 315 if (mode & FMODE_WRITE) 316 r = w = 1; 317 318 name = dentry_name(d_real(file->f_path.dentry, file->f_inode)); 319 if (name == NULL) 320 return -ENOMEM; 321 322 fd = open_file(name, r, w, append); 323 __putname(name); 324 if (fd < 0) 325 return fd; 326 327 mutex_lock(&HOSTFS_I(ino)->open_mutex); 328 /* somebody else had handled it first? */ 329 if ((mode & HOSTFS_I(ino)->mode) == mode) { 330 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 331 close_file(&fd); 332 return 0; 333 } 334 if ((mode | HOSTFS_I(ino)->mode) != mode) { 335 mode |= HOSTFS_I(ino)->mode; 336 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 337 close_file(&fd); 338 goto retry; 339 } 340 if (HOSTFS_I(ino)->fd == -1) { 341 HOSTFS_I(ino)->fd = fd; 342 } else { 343 err = replace_file(fd, HOSTFS_I(ino)->fd); 344 close_file(&fd); 345 if (err < 0) { 346 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 347 return err; 348 } 349 } 350 HOSTFS_I(ino)->mode = mode; 351 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 352 353 return 0; 354 } 355 356 static int hostfs_file_release(struct inode *inode, struct file *file) 357 { 358 filemap_write_and_wait(inode->i_mapping); 359 360 return 0; 361 } 362 363 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 364 int datasync) 365 { 366 struct inode *inode = file->f_mapping->host; 367 int ret; 368 369 ret = file_write_and_wait_range(file, start, end); 370 if (ret) 371 return ret; 372 373 inode_lock(inode); 374 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 375 inode_unlock(inode); 376 377 return ret; 378 } 379 380 static const struct file_operations hostfs_file_fops = { 381 .llseek = generic_file_llseek, 382 .splice_read = generic_file_splice_read, 383 .read_iter = generic_file_read_iter, 384 .write_iter = generic_file_write_iter, 385 .mmap = generic_file_mmap, 386 .open = hostfs_open, 387 .release = hostfs_file_release, 388 .fsync = hostfs_fsync, 389 }; 390 391 static const struct file_operations hostfs_dir_fops = { 392 .llseek = generic_file_llseek, 393 .iterate_shared = hostfs_readdir, 394 .read = generic_read_dir, 395 .open = hostfs_open, 396 .fsync = hostfs_fsync, 397 }; 398 399 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 400 { 401 struct address_space *mapping = page->mapping; 402 struct inode *inode = mapping->host; 403 char *buffer; 404 loff_t base = page_offset(page); 405 int count = PAGE_SIZE; 406 int end_index = inode->i_size >> PAGE_SHIFT; 407 int err; 408 409 if (page->index >= end_index) 410 count = inode->i_size & (PAGE_SIZE-1); 411 412 buffer = kmap(page); 413 414 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 415 if (err != count) { 416 ClearPageUptodate(page); 417 goto out; 418 } 419 420 if (base > inode->i_size) 421 inode->i_size = base; 422 423 if (PageError(page)) 424 ClearPageError(page); 425 err = 0; 426 427 out: 428 kunmap(page); 429 430 unlock_page(page); 431 return err; 432 } 433 434 static int hostfs_readpage(struct file *file, struct page *page) 435 { 436 char *buffer; 437 loff_t start = page_offset(page); 438 int bytes_read, ret = 0; 439 440 buffer = kmap(page); 441 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 442 PAGE_SIZE); 443 if (bytes_read < 0) { 444 ClearPageUptodate(page); 445 SetPageError(page); 446 ret = bytes_read; 447 goto out; 448 } 449 450 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 451 452 ClearPageError(page); 453 SetPageUptodate(page); 454 455 out: 456 flush_dcache_page(page); 457 kunmap(page); 458 unlock_page(page); 459 return ret; 460 } 461 462 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 463 loff_t pos, unsigned len, unsigned flags, 464 struct page **pagep, void **fsdata) 465 { 466 pgoff_t index = pos >> PAGE_SHIFT; 467 468 *pagep = grab_cache_page_write_begin(mapping, index, flags); 469 if (!*pagep) 470 return -ENOMEM; 471 return 0; 472 } 473 474 static int hostfs_write_end(struct file *file, struct address_space *mapping, 475 loff_t pos, unsigned len, unsigned copied, 476 struct page *page, void *fsdata) 477 { 478 struct inode *inode = mapping->host; 479 void *buffer; 480 unsigned from = pos & (PAGE_SIZE - 1); 481 int err; 482 483 buffer = kmap(page); 484 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 485 kunmap(page); 486 487 if (!PageUptodate(page) && err == PAGE_SIZE) 488 SetPageUptodate(page); 489 490 /* 491 * If err > 0, write_file has added err to pos, so we are comparing 492 * i_size against the last byte written. 493 */ 494 if (err > 0 && (pos > inode->i_size)) 495 inode->i_size = pos; 496 unlock_page(page); 497 put_page(page); 498 499 return err; 500 } 501 502 static const struct address_space_operations hostfs_aops = { 503 .writepage = hostfs_writepage, 504 .readpage = hostfs_readpage, 505 .set_page_dirty = __set_page_dirty_nobuffers, 506 .write_begin = hostfs_write_begin, 507 .write_end = hostfs_write_end, 508 }; 509 510 static int read_name(struct inode *ino, char *name) 511 { 512 dev_t rdev; 513 struct hostfs_stat st; 514 int err = stat_file(name, &st, -1); 515 if (err) 516 return err; 517 518 /* Reencode maj and min with the kernel encoding.*/ 519 rdev = MKDEV(st.maj, st.min); 520 521 switch (st.mode & S_IFMT) { 522 case S_IFLNK: 523 ino->i_op = &hostfs_link_iops; 524 break; 525 case S_IFDIR: 526 ino->i_op = &hostfs_dir_iops; 527 ino->i_fop = &hostfs_dir_fops; 528 break; 529 case S_IFCHR: 530 case S_IFBLK: 531 case S_IFIFO: 532 case S_IFSOCK: 533 init_special_inode(ino, st.mode & S_IFMT, rdev); 534 ino->i_op = &hostfs_iops; 535 break; 536 case S_IFREG: 537 ino->i_op = &hostfs_iops; 538 ino->i_fop = &hostfs_file_fops; 539 ino->i_mapping->a_ops = &hostfs_aops; 540 break; 541 default: 542 return -EIO; 543 } 544 545 ino->i_ino = st.ino; 546 ino->i_mode = st.mode; 547 set_nlink(ino, st.nlink); 548 i_uid_write(ino, st.uid); 549 i_gid_write(ino, st.gid); 550 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec }; 551 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec }; 552 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec }; 553 ino->i_size = st.size; 554 ino->i_blocks = st.blocks; 555 return 0; 556 } 557 558 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 559 bool excl) 560 { 561 struct inode *inode; 562 char *name; 563 int error, fd; 564 565 inode = hostfs_iget(dir->i_sb); 566 if (IS_ERR(inode)) { 567 error = PTR_ERR(inode); 568 goto out; 569 } 570 571 error = -ENOMEM; 572 name = dentry_name(dentry); 573 if (name == NULL) 574 goto out_put; 575 576 fd = file_create(name, mode & 0777); 577 if (fd < 0) 578 error = fd; 579 else 580 error = read_name(inode, name); 581 582 __putname(name); 583 if (error) 584 goto out_put; 585 586 HOSTFS_I(inode)->fd = fd; 587 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 588 d_instantiate(dentry, inode); 589 return 0; 590 591 out_put: 592 iput(inode); 593 out: 594 return error; 595 } 596 597 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 598 unsigned int flags) 599 { 600 struct inode *inode; 601 char *name; 602 int err; 603 604 inode = hostfs_iget(ino->i_sb); 605 if (IS_ERR(inode)) 606 goto out; 607 608 err = -ENOMEM; 609 name = dentry_name(dentry); 610 if (name) { 611 err = read_name(inode, name); 612 __putname(name); 613 } 614 if (err) { 615 iput(inode); 616 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 617 } 618 out: 619 return d_splice_alias(inode, dentry); 620 } 621 622 static int hostfs_link(struct dentry *to, struct inode *ino, 623 struct dentry *from) 624 { 625 char *from_name, *to_name; 626 int err; 627 628 if ((from_name = dentry_name(from)) == NULL) 629 return -ENOMEM; 630 to_name = dentry_name(to); 631 if (to_name == NULL) { 632 __putname(from_name); 633 return -ENOMEM; 634 } 635 err = link_file(to_name, from_name); 636 __putname(from_name); 637 __putname(to_name); 638 return err; 639 } 640 641 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 642 { 643 char *file; 644 int err; 645 646 if (append) 647 return -EPERM; 648 649 if ((file = dentry_name(dentry)) == NULL) 650 return -ENOMEM; 651 652 err = unlink_file(file); 653 __putname(file); 654 return err; 655 } 656 657 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 658 const char *to) 659 { 660 char *file; 661 int err; 662 663 if ((file = dentry_name(dentry)) == NULL) 664 return -ENOMEM; 665 err = make_symlink(file, to); 666 __putname(file); 667 return err; 668 } 669 670 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 671 { 672 char *file; 673 int err; 674 675 if ((file = dentry_name(dentry)) == NULL) 676 return -ENOMEM; 677 err = do_mkdir(file, mode); 678 __putname(file); 679 return err; 680 } 681 682 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 683 { 684 char *file; 685 int err; 686 687 if ((file = dentry_name(dentry)) == NULL) 688 return -ENOMEM; 689 err = hostfs_do_rmdir(file); 690 __putname(file); 691 return err; 692 } 693 694 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 695 { 696 struct inode *inode; 697 char *name; 698 int err; 699 700 inode = hostfs_iget(dir->i_sb); 701 if (IS_ERR(inode)) { 702 err = PTR_ERR(inode); 703 goto out; 704 } 705 706 err = -ENOMEM; 707 name = dentry_name(dentry); 708 if (name == NULL) 709 goto out_put; 710 711 init_special_inode(inode, mode, dev); 712 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 713 if (err) 714 goto out_free; 715 716 err = read_name(inode, name); 717 __putname(name); 718 if (err) 719 goto out_put; 720 721 d_instantiate(dentry, inode); 722 return 0; 723 724 out_free: 725 __putname(name); 726 out_put: 727 iput(inode); 728 out: 729 return err; 730 } 731 732 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 733 struct inode *new_dir, struct dentry *new_dentry, 734 unsigned int flags) 735 { 736 char *old_name, *new_name; 737 int err; 738 739 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 740 return -EINVAL; 741 742 old_name = dentry_name(old_dentry); 743 if (old_name == NULL) 744 return -ENOMEM; 745 new_name = dentry_name(new_dentry); 746 if (new_name == NULL) { 747 __putname(old_name); 748 return -ENOMEM; 749 } 750 if (!flags) 751 err = rename_file(old_name, new_name); 752 else 753 err = rename2_file(old_name, new_name, flags); 754 755 __putname(old_name); 756 __putname(new_name); 757 return err; 758 } 759 760 static int hostfs_permission(struct inode *ino, int desired) 761 { 762 char *name; 763 int r = 0, w = 0, x = 0, err; 764 765 if (desired & MAY_NOT_BLOCK) 766 return -ECHILD; 767 768 if (desired & MAY_READ) r = 1; 769 if (desired & MAY_WRITE) w = 1; 770 if (desired & MAY_EXEC) x = 1; 771 name = inode_name(ino); 772 if (name == NULL) 773 return -ENOMEM; 774 775 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 776 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 777 err = 0; 778 else 779 err = access_file(name, r, w, x); 780 __putname(name); 781 if (!err) 782 err = generic_permission(ino, desired); 783 return err; 784 } 785 786 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 787 { 788 struct inode *inode = d_inode(dentry); 789 struct hostfs_iattr attrs; 790 char *name; 791 int err; 792 793 int fd = HOSTFS_I(inode)->fd; 794 795 err = setattr_prepare(dentry, attr); 796 if (err) 797 return err; 798 799 if (append) 800 attr->ia_valid &= ~ATTR_SIZE; 801 802 attrs.ia_valid = 0; 803 if (attr->ia_valid & ATTR_MODE) { 804 attrs.ia_valid |= HOSTFS_ATTR_MODE; 805 attrs.ia_mode = attr->ia_mode; 806 } 807 if (attr->ia_valid & ATTR_UID) { 808 attrs.ia_valid |= HOSTFS_ATTR_UID; 809 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 810 } 811 if (attr->ia_valid & ATTR_GID) { 812 attrs.ia_valid |= HOSTFS_ATTR_GID; 813 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 814 } 815 if (attr->ia_valid & ATTR_SIZE) { 816 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 817 attrs.ia_size = attr->ia_size; 818 } 819 if (attr->ia_valid & ATTR_ATIME) { 820 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 821 attrs.ia_atime = (struct hostfs_timespec) 822 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 823 } 824 if (attr->ia_valid & ATTR_MTIME) { 825 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 826 attrs.ia_mtime = (struct hostfs_timespec) 827 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 828 } 829 if (attr->ia_valid & ATTR_CTIME) { 830 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 831 attrs.ia_ctime = (struct hostfs_timespec) 832 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 833 } 834 if (attr->ia_valid & ATTR_ATIME_SET) { 835 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 836 } 837 if (attr->ia_valid & ATTR_MTIME_SET) { 838 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 839 } 840 name = dentry_name(dentry); 841 if (name == NULL) 842 return -ENOMEM; 843 err = set_attr(name, &attrs, fd); 844 __putname(name); 845 if (err) 846 return err; 847 848 if ((attr->ia_valid & ATTR_SIZE) && 849 attr->ia_size != i_size_read(inode)) 850 truncate_setsize(inode, attr->ia_size); 851 852 setattr_copy(inode, attr); 853 mark_inode_dirty(inode); 854 return 0; 855 } 856 857 static const struct inode_operations hostfs_iops = { 858 .permission = hostfs_permission, 859 .setattr = hostfs_setattr, 860 }; 861 862 static const struct inode_operations hostfs_dir_iops = { 863 .create = hostfs_create, 864 .lookup = hostfs_lookup, 865 .link = hostfs_link, 866 .unlink = hostfs_unlink, 867 .symlink = hostfs_symlink, 868 .mkdir = hostfs_mkdir, 869 .rmdir = hostfs_rmdir, 870 .mknod = hostfs_mknod, 871 .rename = hostfs_rename2, 872 .permission = hostfs_permission, 873 .setattr = hostfs_setattr, 874 }; 875 876 static const char *hostfs_get_link(struct dentry *dentry, 877 struct inode *inode, 878 struct delayed_call *done) 879 { 880 char *link; 881 if (!dentry) 882 return ERR_PTR(-ECHILD); 883 link = kmalloc(PATH_MAX, GFP_KERNEL); 884 if (link) { 885 char *path = dentry_name(dentry); 886 int err = -ENOMEM; 887 if (path) { 888 err = hostfs_do_readlink(path, link, PATH_MAX); 889 if (err == PATH_MAX) 890 err = -E2BIG; 891 __putname(path); 892 } 893 if (err < 0) { 894 kfree(link); 895 return ERR_PTR(err); 896 } 897 } else { 898 return ERR_PTR(-ENOMEM); 899 } 900 901 set_delayed_call(done, kfree_link, link); 902 return link; 903 } 904 905 static const struct inode_operations hostfs_link_iops = { 906 .get_link = hostfs_get_link, 907 }; 908 909 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 910 { 911 struct inode *root_inode; 912 char *host_root_path, *req_root = d; 913 int err; 914 915 sb->s_blocksize = 1024; 916 sb->s_blocksize_bits = 10; 917 sb->s_magic = HOSTFS_SUPER_MAGIC; 918 sb->s_op = &hostfs_sbops; 919 sb->s_d_op = &simple_dentry_operations; 920 sb->s_maxbytes = MAX_LFS_FILESIZE; 921 922 /* NULL is printed as '(null)' by printf(): avoid that. */ 923 if (req_root == NULL) 924 req_root = ""; 925 926 err = -ENOMEM; 927 sb->s_fs_info = host_root_path = 928 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root); 929 if (host_root_path == NULL) 930 goto out; 931 932 root_inode = new_inode(sb); 933 if (!root_inode) 934 goto out; 935 936 err = read_name(root_inode, host_root_path); 937 if (err) 938 goto out_put; 939 940 if (S_ISLNK(root_inode->i_mode)) { 941 char *name = follow_link(host_root_path); 942 if (IS_ERR(name)) { 943 err = PTR_ERR(name); 944 goto out_put; 945 } 946 err = read_name(root_inode, name); 947 kfree(name); 948 if (err) 949 goto out_put; 950 } 951 952 err = -ENOMEM; 953 sb->s_root = d_make_root(root_inode); 954 if (sb->s_root == NULL) 955 goto out; 956 957 return 0; 958 959 out_put: 960 iput(root_inode); 961 out: 962 return err; 963 } 964 965 static struct dentry *hostfs_read_sb(struct file_system_type *type, 966 int flags, const char *dev_name, 967 void *data) 968 { 969 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 970 } 971 972 static void hostfs_kill_sb(struct super_block *s) 973 { 974 kill_anon_super(s); 975 kfree(s->s_fs_info); 976 } 977 978 static struct file_system_type hostfs_type = { 979 .owner = THIS_MODULE, 980 .name = "hostfs", 981 .mount = hostfs_read_sb, 982 .kill_sb = hostfs_kill_sb, 983 .fs_flags = 0, 984 }; 985 MODULE_ALIAS_FS("hostfs"); 986 987 static int __init init_hostfs(void) 988 { 989 return register_filesystem(&hostfs_type); 990 } 991 992 static void __exit exit_hostfs(void) 993 { 994 unregister_filesystem(&hostfs_type); 995 } 996 997 module_init(init_hostfs) 998 module_exit(exit_hostfs) 999 MODULE_LICENSE("GPL"); 1000