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_ACCOUNT); 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_free_inode(struct inode *inode) 247 { 248 kfree(HOSTFS_I(inode)); 249 } 250 251 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 252 { 253 const char *root_path = root->d_sb->s_fs_info; 254 size_t offset = strlen(root_ino) + 1; 255 256 if (strlen(root_path) > offset) 257 seq_show_option(seq, root_path + offset, NULL); 258 259 if (append) 260 seq_puts(seq, ",append"); 261 262 return 0; 263 } 264 265 static const struct super_operations hostfs_sbops = { 266 .alloc_inode = hostfs_alloc_inode, 267 .free_inode = hostfs_free_inode, 268 .evict_inode = hostfs_evict_inode, 269 .statfs = hostfs_statfs, 270 .show_options = hostfs_show_options, 271 }; 272 273 static int hostfs_readdir(struct file *file, struct dir_context *ctx) 274 { 275 void *dir; 276 char *name; 277 unsigned long long next, ino; 278 int error, len; 279 unsigned int type; 280 281 name = dentry_name(file->f_path.dentry); 282 if (name == NULL) 283 return -ENOMEM; 284 dir = open_dir(name, &error); 285 __putname(name); 286 if (dir == NULL) 287 return -error; 288 next = ctx->pos; 289 seek_dir(dir, next); 290 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 291 if (!dir_emit(ctx, name, len, ino, type)) 292 break; 293 ctx->pos = next; 294 } 295 close_dir(dir); 296 return 0; 297 } 298 299 static int hostfs_open(struct inode *ino, struct file *file) 300 { 301 char *name; 302 fmode_t mode; 303 int err; 304 int r, w, fd; 305 306 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 307 if ((mode & HOSTFS_I(ino)->mode) == mode) 308 return 0; 309 310 mode |= HOSTFS_I(ino)->mode; 311 312 retry: 313 r = w = 0; 314 315 if (mode & FMODE_READ) 316 r = 1; 317 if (mode & FMODE_WRITE) 318 r = w = 1; 319 320 name = dentry_name(file->f_path.dentry); 321 if (name == NULL) 322 return -ENOMEM; 323 324 fd = open_file(name, r, w, append); 325 __putname(name); 326 if (fd < 0) 327 return fd; 328 329 mutex_lock(&HOSTFS_I(ino)->open_mutex); 330 /* somebody else had handled it first? */ 331 if ((mode & HOSTFS_I(ino)->mode) == mode) { 332 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 333 close_file(&fd); 334 return 0; 335 } 336 if ((mode | HOSTFS_I(ino)->mode) != mode) { 337 mode |= HOSTFS_I(ino)->mode; 338 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 339 close_file(&fd); 340 goto retry; 341 } 342 if (HOSTFS_I(ino)->fd == -1) { 343 HOSTFS_I(ino)->fd = fd; 344 } else { 345 err = replace_file(fd, HOSTFS_I(ino)->fd); 346 close_file(&fd); 347 if (err < 0) { 348 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 349 return err; 350 } 351 } 352 HOSTFS_I(ino)->mode = mode; 353 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 354 355 return 0; 356 } 357 358 static int hostfs_file_release(struct inode *inode, struct file *file) 359 { 360 filemap_write_and_wait(inode->i_mapping); 361 362 return 0; 363 } 364 365 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 366 int datasync) 367 { 368 struct inode *inode = file->f_mapping->host; 369 int ret; 370 371 ret = file_write_and_wait_range(file, start, end); 372 if (ret) 373 return ret; 374 375 inode_lock(inode); 376 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 377 inode_unlock(inode); 378 379 return ret; 380 } 381 382 static const struct file_operations hostfs_file_fops = { 383 .llseek = generic_file_llseek, 384 .splice_read = generic_file_splice_read, 385 .read_iter = generic_file_read_iter, 386 .write_iter = generic_file_write_iter, 387 .mmap = generic_file_mmap, 388 .open = hostfs_open, 389 .release = hostfs_file_release, 390 .fsync = hostfs_fsync, 391 }; 392 393 static const struct file_operations hostfs_dir_fops = { 394 .llseek = generic_file_llseek, 395 .iterate_shared = hostfs_readdir, 396 .read = generic_read_dir, 397 .open = hostfs_open, 398 .fsync = hostfs_fsync, 399 }; 400 401 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 402 { 403 struct address_space *mapping = page->mapping; 404 struct inode *inode = mapping->host; 405 char *buffer; 406 loff_t base = page_offset(page); 407 int count = PAGE_SIZE; 408 int end_index = inode->i_size >> PAGE_SHIFT; 409 int err; 410 411 if (page->index >= end_index) 412 count = inode->i_size & (PAGE_SIZE-1); 413 414 buffer = kmap(page); 415 416 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 417 if (err != count) { 418 ClearPageUptodate(page); 419 goto out; 420 } 421 422 if (base > inode->i_size) 423 inode->i_size = base; 424 425 if (PageError(page)) 426 ClearPageError(page); 427 err = 0; 428 429 out: 430 kunmap(page); 431 432 unlock_page(page); 433 return err; 434 } 435 436 static int hostfs_readpage(struct file *file, struct page *page) 437 { 438 char *buffer; 439 loff_t start = page_offset(page); 440 int bytes_read, ret = 0; 441 442 buffer = kmap(page); 443 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 444 PAGE_SIZE); 445 if (bytes_read < 0) { 446 ClearPageUptodate(page); 447 SetPageError(page); 448 ret = bytes_read; 449 goto out; 450 } 451 452 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 453 454 ClearPageError(page); 455 SetPageUptodate(page); 456 457 out: 458 flush_dcache_page(page); 459 kunmap(page); 460 unlock_page(page); 461 return ret; 462 } 463 464 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 465 loff_t pos, unsigned len, unsigned flags, 466 struct page **pagep, void **fsdata) 467 { 468 pgoff_t index = pos >> PAGE_SHIFT; 469 470 *pagep = grab_cache_page_write_begin(mapping, index, flags); 471 if (!*pagep) 472 return -ENOMEM; 473 return 0; 474 } 475 476 static int hostfs_write_end(struct file *file, struct address_space *mapping, 477 loff_t pos, unsigned len, unsigned copied, 478 struct page *page, void *fsdata) 479 { 480 struct inode *inode = mapping->host; 481 void *buffer; 482 unsigned from = pos & (PAGE_SIZE - 1); 483 int err; 484 485 buffer = kmap(page); 486 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 487 kunmap(page); 488 489 if (!PageUptodate(page) && err == PAGE_SIZE) 490 SetPageUptodate(page); 491 492 /* 493 * If err > 0, write_file has added err to pos, so we are comparing 494 * i_size against the last byte written. 495 */ 496 if (err > 0 && (pos > inode->i_size)) 497 inode->i_size = pos; 498 unlock_page(page); 499 put_page(page); 500 501 return err; 502 } 503 504 static const struct address_space_operations hostfs_aops = { 505 .writepage = hostfs_writepage, 506 .readpage = hostfs_readpage, 507 .set_page_dirty = __set_page_dirty_nobuffers, 508 .write_begin = hostfs_write_begin, 509 .write_end = hostfs_write_end, 510 }; 511 512 static int read_name(struct inode *ino, char *name) 513 { 514 dev_t rdev; 515 struct hostfs_stat st; 516 int err = stat_file(name, &st, -1); 517 if (err) 518 return err; 519 520 /* Reencode maj and min with the kernel encoding.*/ 521 rdev = MKDEV(st.maj, st.min); 522 523 switch (st.mode & S_IFMT) { 524 case S_IFLNK: 525 ino->i_op = &hostfs_link_iops; 526 break; 527 case S_IFDIR: 528 ino->i_op = &hostfs_dir_iops; 529 ino->i_fop = &hostfs_dir_fops; 530 break; 531 case S_IFCHR: 532 case S_IFBLK: 533 case S_IFIFO: 534 case S_IFSOCK: 535 init_special_inode(ino, st.mode & S_IFMT, rdev); 536 ino->i_op = &hostfs_iops; 537 break; 538 case S_IFREG: 539 ino->i_op = &hostfs_iops; 540 ino->i_fop = &hostfs_file_fops; 541 ino->i_mapping->a_ops = &hostfs_aops; 542 break; 543 default: 544 return -EIO; 545 } 546 547 ino->i_ino = st.ino; 548 ino->i_mode = st.mode; 549 set_nlink(ino, st.nlink); 550 i_uid_write(ino, st.uid); 551 i_gid_write(ino, st.gid); 552 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec }; 553 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec }; 554 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec }; 555 ino->i_size = st.size; 556 ino->i_blocks = st.blocks; 557 return 0; 558 } 559 560 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 561 bool excl) 562 { 563 struct inode *inode; 564 char *name; 565 int error, fd; 566 567 inode = hostfs_iget(dir->i_sb); 568 if (IS_ERR(inode)) { 569 error = PTR_ERR(inode); 570 goto out; 571 } 572 573 error = -ENOMEM; 574 name = dentry_name(dentry); 575 if (name == NULL) 576 goto out_put; 577 578 fd = file_create(name, mode & 0777); 579 if (fd < 0) 580 error = fd; 581 else 582 error = read_name(inode, name); 583 584 __putname(name); 585 if (error) 586 goto out_put; 587 588 HOSTFS_I(inode)->fd = fd; 589 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 590 d_instantiate(dentry, inode); 591 return 0; 592 593 out_put: 594 iput(inode); 595 out: 596 return error; 597 } 598 599 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 600 unsigned int flags) 601 { 602 struct inode *inode; 603 char *name; 604 int err; 605 606 inode = hostfs_iget(ino->i_sb); 607 if (IS_ERR(inode)) 608 goto out; 609 610 err = -ENOMEM; 611 name = dentry_name(dentry); 612 if (name) { 613 err = read_name(inode, name); 614 __putname(name); 615 } 616 if (err) { 617 iput(inode); 618 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 619 } 620 out: 621 return d_splice_alias(inode, dentry); 622 } 623 624 static int hostfs_link(struct dentry *to, struct inode *ino, 625 struct dentry *from) 626 { 627 char *from_name, *to_name; 628 int err; 629 630 if ((from_name = dentry_name(from)) == NULL) 631 return -ENOMEM; 632 to_name = dentry_name(to); 633 if (to_name == NULL) { 634 __putname(from_name); 635 return -ENOMEM; 636 } 637 err = link_file(to_name, from_name); 638 __putname(from_name); 639 __putname(to_name); 640 return err; 641 } 642 643 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 644 { 645 char *file; 646 int err; 647 648 if (append) 649 return -EPERM; 650 651 if ((file = dentry_name(dentry)) == NULL) 652 return -ENOMEM; 653 654 err = unlink_file(file); 655 __putname(file); 656 return err; 657 } 658 659 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 660 const char *to) 661 { 662 char *file; 663 int err; 664 665 if ((file = dentry_name(dentry)) == NULL) 666 return -ENOMEM; 667 err = make_symlink(file, to); 668 __putname(file); 669 return err; 670 } 671 672 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 673 { 674 char *file; 675 int err; 676 677 if ((file = dentry_name(dentry)) == NULL) 678 return -ENOMEM; 679 err = do_mkdir(file, mode); 680 __putname(file); 681 return err; 682 } 683 684 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 685 { 686 char *file; 687 int err; 688 689 if ((file = dentry_name(dentry)) == NULL) 690 return -ENOMEM; 691 err = hostfs_do_rmdir(file); 692 __putname(file); 693 return err; 694 } 695 696 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 697 { 698 struct inode *inode; 699 char *name; 700 int err; 701 702 inode = hostfs_iget(dir->i_sb); 703 if (IS_ERR(inode)) { 704 err = PTR_ERR(inode); 705 goto out; 706 } 707 708 err = -ENOMEM; 709 name = dentry_name(dentry); 710 if (name == NULL) 711 goto out_put; 712 713 init_special_inode(inode, mode, dev); 714 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 715 if (err) 716 goto out_free; 717 718 err = read_name(inode, name); 719 __putname(name); 720 if (err) 721 goto out_put; 722 723 d_instantiate(dentry, inode); 724 return 0; 725 726 out_free: 727 __putname(name); 728 out_put: 729 iput(inode); 730 out: 731 return err; 732 } 733 734 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 735 struct inode *new_dir, struct dentry *new_dentry, 736 unsigned int flags) 737 { 738 char *old_name, *new_name; 739 int err; 740 741 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 742 return -EINVAL; 743 744 old_name = dentry_name(old_dentry); 745 if (old_name == NULL) 746 return -ENOMEM; 747 new_name = dentry_name(new_dentry); 748 if (new_name == NULL) { 749 __putname(old_name); 750 return -ENOMEM; 751 } 752 if (!flags) 753 err = rename_file(old_name, new_name); 754 else 755 err = rename2_file(old_name, new_name, flags); 756 757 __putname(old_name); 758 __putname(new_name); 759 return err; 760 } 761 762 static int hostfs_permission(struct inode *ino, int desired) 763 { 764 char *name; 765 int r = 0, w = 0, x = 0, err; 766 767 if (desired & MAY_NOT_BLOCK) 768 return -ECHILD; 769 770 if (desired & MAY_READ) r = 1; 771 if (desired & MAY_WRITE) w = 1; 772 if (desired & MAY_EXEC) x = 1; 773 name = inode_name(ino); 774 if (name == NULL) 775 return -ENOMEM; 776 777 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 778 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 779 err = 0; 780 else 781 err = access_file(name, r, w, x); 782 __putname(name); 783 if (!err) 784 err = generic_permission(ino, desired); 785 return err; 786 } 787 788 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 789 { 790 struct inode *inode = d_inode(dentry); 791 struct hostfs_iattr attrs; 792 char *name; 793 int err; 794 795 int fd = HOSTFS_I(inode)->fd; 796 797 err = setattr_prepare(dentry, attr); 798 if (err) 799 return err; 800 801 if (append) 802 attr->ia_valid &= ~ATTR_SIZE; 803 804 attrs.ia_valid = 0; 805 if (attr->ia_valid & ATTR_MODE) { 806 attrs.ia_valid |= HOSTFS_ATTR_MODE; 807 attrs.ia_mode = attr->ia_mode; 808 } 809 if (attr->ia_valid & ATTR_UID) { 810 attrs.ia_valid |= HOSTFS_ATTR_UID; 811 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 812 } 813 if (attr->ia_valid & ATTR_GID) { 814 attrs.ia_valid |= HOSTFS_ATTR_GID; 815 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 816 } 817 if (attr->ia_valid & ATTR_SIZE) { 818 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 819 attrs.ia_size = attr->ia_size; 820 } 821 if (attr->ia_valid & ATTR_ATIME) { 822 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 823 attrs.ia_atime = (struct hostfs_timespec) 824 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 825 } 826 if (attr->ia_valid & ATTR_MTIME) { 827 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 828 attrs.ia_mtime = (struct hostfs_timespec) 829 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 830 } 831 if (attr->ia_valid & ATTR_CTIME) { 832 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 833 attrs.ia_ctime = (struct hostfs_timespec) 834 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 835 } 836 if (attr->ia_valid & ATTR_ATIME_SET) { 837 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 838 } 839 if (attr->ia_valid & ATTR_MTIME_SET) { 840 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 841 } 842 name = dentry_name(dentry); 843 if (name == NULL) 844 return -ENOMEM; 845 err = set_attr(name, &attrs, fd); 846 __putname(name); 847 if (err) 848 return err; 849 850 if ((attr->ia_valid & ATTR_SIZE) && 851 attr->ia_size != i_size_read(inode)) 852 truncate_setsize(inode, attr->ia_size); 853 854 setattr_copy(inode, attr); 855 mark_inode_dirty(inode); 856 return 0; 857 } 858 859 static const struct inode_operations hostfs_iops = { 860 .permission = hostfs_permission, 861 .setattr = hostfs_setattr, 862 }; 863 864 static const struct inode_operations hostfs_dir_iops = { 865 .create = hostfs_create, 866 .lookup = hostfs_lookup, 867 .link = hostfs_link, 868 .unlink = hostfs_unlink, 869 .symlink = hostfs_symlink, 870 .mkdir = hostfs_mkdir, 871 .rmdir = hostfs_rmdir, 872 .mknod = hostfs_mknod, 873 .rename = hostfs_rename2, 874 .permission = hostfs_permission, 875 .setattr = hostfs_setattr, 876 }; 877 878 static const char *hostfs_get_link(struct dentry *dentry, 879 struct inode *inode, 880 struct delayed_call *done) 881 { 882 char *link; 883 if (!dentry) 884 return ERR_PTR(-ECHILD); 885 link = kmalloc(PATH_MAX, GFP_KERNEL); 886 if (link) { 887 char *path = dentry_name(dentry); 888 int err = -ENOMEM; 889 if (path) { 890 err = hostfs_do_readlink(path, link, PATH_MAX); 891 if (err == PATH_MAX) 892 err = -E2BIG; 893 __putname(path); 894 } 895 if (err < 0) { 896 kfree(link); 897 return ERR_PTR(err); 898 } 899 } else { 900 return ERR_PTR(-ENOMEM); 901 } 902 903 set_delayed_call(done, kfree_link, link); 904 return link; 905 } 906 907 static const struct inode_operations hostfs_link_iops = { 908 .get_link = hostfs_get_link, 909 }; 910 911 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 912 { 913 struct inode *root_inode; 914 char *host_root_path, *req_root = d; 915 int err; 916 917 sb->s_blocksize = 1024; 918 sb->s_blocksize_bits = 10; 919 sb->s_magic = HOSTFS_SUPER_MAGIC; 920 sb->s_op = &hostfs_sbops; 921 sb->s_d_op = &simple_dentry_operations; 922 sb->s_maxbytes = MAX_LFS_FILESIZE; 923 924 /* NULL is printed as <NULL> by sprintf: avoid that. */ 925 if (req_root == NULL) 926 req_root = ""; 927 928 err = -ENOMEM; 929 sb->s_fs_info = host_root_path = 930 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 931 if (host_root_path == NULL) 932 goto out; 933 934 sprintf(host_root_path, "%s/%s", root_ino, req_root); 935 936 root_inode = new_inode(sb); 937 if (!root_inode) 938 goto out; 939 940 err = read_name(root_inode, host_root_path); 941 if (err) 942 goto out_put; 943 944 if (S_ISLNK(root_inode->i_mode)) { 945 char *name = follow_link(host_root_path); 946 if (IS_ERR(name)) { 947 err = PTR_ERR(name); 948 goto out_put; 949 } 950 err = read_name(root_inode, name); 951 kfree(name); 952 if (err) 953 goto out_put; 954 } 955 956 err = -ENOMEM; 957 sb->s_root = d_make_root(root_inode); 958 if (sb->s_root == NULL) 959 goto out; 960 961 return 0; 962 963 out_put: 964 iput(root_inode); 965 out: 966 return err; 967 } 968 969 static struct dentry *hostfs_read_sb(struct file_system_type *type, 970 int flags, const char *dev_name, 971 void *data) 972 { 973 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 974 } 975 976 static void hostfs_kill_sb(struct super_block *s) 977 { 978 kill_anon_super(s); 979 kfree(s->s_fs_info); 980 } 981 982 static struct file_system_type hostfs_type = { 983 .owner = THIS_MODULE, 984 .name = "hostfs", 985 .mount = hostfs_read_sb, 986 .kill_sb = hostfs_kill_sb, 987 .fs_flags = 0, 988 }; 989 MODULE_ALIAS_FS("hostfs"); 990 991 static int __init init_hostfs(void) 992 { 993 return register_filesystem(&hostfs_type); 994 } 995 996 static void __exit exit_hostfs(void) 997 { 998 unregister_filesystem(&hostfs_type); 999 } 1000 1001 module_init(init_hostfs) 1002 module_exit(exit_hostfs) 1003 MODULE_LICENSE("GPL"); 1004