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/writeback.h> 18 #include <linux/mount.h> 19 #include <linux/namei.h> 20 #include "hostfs.h" 21 #include <init.h> 22 #include <kern.h> 23 24 struct hostfs_inode_info { 25 int fd; 26 fmode_t mode; 27 struct inode vfs_inode; 28 struct mutex open_mutex; 29 }; 30 31 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 32 { 33 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 34 } 35 36 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 37 38 static struct kmem_cache *hostfs_inode_cache; 39 40 /* Changed in hostfs_args before the kernel starts running */ 41 static char *root_ino = ""; 42 static int append = 0; 43 44 static const struct inode_operations hostfs_iops; 45 static const struct inode_operations hostfs_dir_iops; 46 static const struct inode_operations hostfs_link_iops; 47 48 #ifndef MODULE 49 static int __init hostfs_args(char *options, int *add) 50 { 51 char *ptr; 52 53 ptr = strchr(options, ','); 54 if (ptr != NULL) 55 *ptr++ = '\0'; 56 if (*options != '\0') 57 root_ino = options; 58 59 options = ptr; 60 while (options) { 61 ptr = strchr(options, ','); 62 if (ptr != NULL) 63 *ptr++ = '\0'; 64 if (*options != '\0') { 65 if (!strcmp(options, "append")) 66 append = 1; 67 else printf("hostfs_args - unsupported option - %s\n", 68 options); 69 } 70 options = ptr; 71 } 72 return 0; 73 } 74 75 __uml_setup("hostfs=", hostfs_args, 76 "hostfs=<root dir>,<flags>,...\n" 77 " This is used to set hostfs parameters. The root directory argument\n" 78 " is used to confine all hostfs mounts to within the specified directory\n" 79 " tree on the host. If this isn't specified, then a user inside UML can\n" 80 " mount anything on the host that's accessible to the user that's running\n" 81 " it.\n" 82 " The only flag currently supported is 'append', which specifies that all\n" 83 " files opened by hostfs will be opened in append mode.\n\n" 84 ); 85 #endif 86 87 static char *__dentry_name(struct dentry *dentry, char *name) 88 { 89 char *p = dentry_path_raw(dentry, name, PATH_MAX); 90 char *root; 91 size_t len; 92 93 root = dentry->d_sb->s_fs_info; 94 len = strlen(root); 95 if (IS_ERR(p)) { 96 __putname(name); 97 return NULL; 98 } 99 100 /* 101 * This function relies on the fact that dentry_path_raw() will place 102 * the path name at the end of the provided buffer. 103 */ 104 BUG_ON(p + strlen(p) + 1 != name + PATH_MAX); 105 106 strscpy(name, root, PATH_MAX); 107 if (len > p - name) { 108 __putname(name); 109 return NULL; 110 } 111 112 if (p > name + len) 113 strcpy(name + len, p); 114 115 return name; 116 } 117 118 static char *dentry_name(struct dentry *dentry) 119 { 120 char *name = __getname(); 121 if (!name) 122 return NULL; 123 124 return __dentry_name(dentry, name); 125 } 126 127 static char *inode_name(struct inode *ino) 128 { 129 struct dentry *dentry; 130 char *name; 131 132 dentry = d_find_alias(ino); 133 if (!dentry) 134 return NULL; 135 136 name = dentry_name(dentry); 137 138 dput(dentry); 139 140 return name; 141 } 142 143 static char *follow_link(char *link) 144 { 145 char *name, *resolved, *end; 146 int n; 147 148 name = kmalloc(PATH_MAX, GFP_KERNEL); 149 if (!name) { 150 n = -ENOMEM; 151 goto out_free; 152 } 153 154 n = hostfs_do_readlink(link, name, PATH_MAX); 155 if (n < 0) 156 goto out_free; 157 else if (n == PATH_MAX) { 158 n = -E2BIG; 159 goto out_free; 160 } 161 162 if (*name == '/') 163 return name; 164 165 end = strrchr(link, '/'); 166 if (end == NULL) 167 return name; 168 169 *(end + 1) = '\0'; 170 171 resolved = kasprintf(GFP_KERNEL, "%s%s", link, name); 172 if (resolved == NULL) { 173 n = -ENOMEM; 174 goto out_free; 175 } 176 177 kfree(name); 178 return resolved; 179 180 out_free: 181 kfree(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 = alloc_inode_sb(sb, hostfs_inode_cache, 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 kmem_cache_free(hostfs_inode_cache, 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_dentry(file)); 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 .splice_write = iter_file_splice_write, 386 .read_iter = generic_file_read_iter, 387 .write_iter = generic_file_write_iter, 388 .mmap = generic_file_mmap, 389 .open = hostfs_open, 390 .release = hostfs_file_release, 391 .fsync = hostfs_fsync, 392 }; 393 394 static const struct file_operations hostfs_dir_fops = { 395 .llseek = generic_file_llseek, 396 .iterate_shared = hostfs_readdir, 397 .read = generic_read_dir, 398 .open = hostfs_open, 399 .fsync = hostfs_fsync, 400 }; 401 402 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 403 { 404 struct address_space *mapping = page->mapping; 405 struct inode *inode = mapping->host; 406 char *buffer; 407 loff_t base = page_offset(page); 408 int count = PAGE_SIZE; 409 int end_index = inode->i_size >> PAGE_SHIFT; 410 int err; 411 412 if (page->index >= end_index) 413 count = inode->i_size & (PAGE_SIZE-1); 414 415 buffer = kmap_local_page(page); 416 417 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 418 if (err != count) { 419 if (err >= 0) 420 err = -EIO; 421 mapping_set_error(mapping, err); 422 goto out; 423 } 424 425 if (base > inode->i_size) 426 inode->i_size = base; 427 428 err = 0; 429 430 out: 431 kunmap_local(buffer); 432 unlock_page(page); 433 434 return err; 435 } 436 437 static int hostfs_read_folio(struct file *file, struct folio *folio) 438 { 439 struct page *page = &folio->page; 440 char *buffer; 441 loff_t start = page_offset(page); 442 int bytes_read, ret = 0; 443 444 buffer = kmap_local_page(page); 445 bytes_read = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 446 PAGE_SIZE); 447 if (bytes_read < 0) { 448 ClearPageUptodate(page); 449 SetPageError(page); 450 ret = bytes_read; 451 goto out; 452 } 453 454 memset(buffer + bytes_read, 0, PAGE_SIZE - bytes_read); 455 456 ClearPageError(page); 457 SetPageUptodate(page); 458 459 out: 460 flush_dcache_page(page); 461 kunmap_local(buffer); 462 unlock_page(page); 463 464 return ret; 465 } 466 467 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 468 loff_t pos, unsigned len, 469 struct page **pagep, void **fsdata) 470 { 471 pgoff_t index = pos >> PAGE_SHIFT; 472 473 *pagep = grab_cache_page_write_begin(mapping, index); 474 if (!*pagep) 475 return -ENOMEM; 476 return 0; 477 } 478 479 static int hostfs_write_end(struct file *file, struct address_space *mapping, 480 loff_t pos, unsigned len, unsigned copied, 481 struct page *page, void *fsdata) 482 { 483 struct inode *inode = mapping->host; 484 void *buffer; 485 unsigned from = pos & (PAGE_SIZE - 1); 486 int err; 487 488 buffer = kmap_local_page(page); 489 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 490 kunmap_local(buffer); 491 492 if (!PageUptodate(page) && err == PAGE_SIZE) 493 SetPageUptodate(page); 494 495 /* 496 * If err > 0, write_file has added err to pos, so we are comparing 497 * i_size against the last byte written. 498 */ 499 if (err > 0 && (pos > inode->i_size)) 500 inode->i_size = pos; 501 unlock_page(page); 502 put_page(page); 503 504 return err; 505 } 506 507 static const struct address_space_operations hostfs_aops = { 508 .writepage = hostfs_writepage, 509 .read_folio = hostfs_read_folio, 510 .dirty_folio = filemap_dirty_folio, 511 .write_begin = hostfs_write_begin, 512 .write_end = hostfs_write_end, 513 }; 514 515 static int read_name(struct inode *ino, char *name) 516 { 517 dev_t rdev; 518 struct hostfs_stat st; 519 int err = stat_file(name, &st, -1); 520 if (err) 521 return err; 522 523 /* Reencode maj and min with the kernel encoding.*/ 524 rdev = MKDEV(st.maj, st.min); 525 526 switch (st.mode & S_IFMT) { 527 case S_IFLNK: 528 ino->i_op = &hostfs_link_iops; 529 break; 530 case S_IFDIR: 531 ino->i_op = &hostfs_dir_iops; 532 ino->i_fop = &hostfs_dir_fops; 533 break; 534 case S_IFCHR: 535 case S_IFBLK: 536 case S_IFIFO: 537 case S_IFSOCK: 538 init_special_inode(ino, st.mode & S_IFMT, rdev); 539 ino->i_op = &hostfs_iops; 540 break; 541 case S_IFREG: 542 ino->i_op = &hostfs_iops; 543 ino->i_fop = &hostfs_file_fops; 544 ino->i_mapping->a_ops = &hostfs_aops; 545 break; 546 default: 547 return -EIO; 548 } 549 550 ino->i_ino = st.ino; 551 ino->i_mode = st.mode; 552 set_nlink(ino, st.nlink); 553 i_uid_write(ino, st.uid); 554 i_gid_write(ino, st.gid); 555 ino->i_atime = (struct timespec64){ st.atime.tv_sec, st.atime.tv_nsec }; 556 ino->i_mtime = (struct timespec64){ st.mtime.tv_sec, st.mtime.tv_nsec }; 557 ino->i_ctime = (struct timespec64){ st.ctime.tv_sec, st.ctime.tv_nsec }; 558 ino->i_size = st.size; 559 ino->i_blocks = st.blocks; 560 return 0; 561 } 562 563 static int hostfs_create(struct mnt_idmap *idmap, struct inode *dir, 564 struct dentry *dentry, umode_t mode, bool excl) 565 { 566 struct inode *inode; 567 char *name; 568 int error, fd; 569 570 inode = hostfs_iget(dir->i_sb); 571 if (IS_ERR(inode)) { 572 error = PTR_ERR(inode); 573 goto out; 574 } 575 576 error = -ENOMEM; 577 name = dentry_name(dentry); 578 if (name == NULL) 579 goto out_put; 580 581 fd = file_create(name, mode & 0777); 582 if (fd < 0) 583 error = fd; 584 else 585 error = read_name(inode, name); 586 587 __putname(name); 588 if (error) 589 goto out_put; 590 591 HOSTFS_I(inode)->fd = fd; 592 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 593 d_instantiate(dentry, inode); 594 return 0; 595 596 out_put: 597 iput(inode); 598 out: 599 return error; 600 } 601 602 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 603 unsigned int flags) 604 { 605 struct inode *inode; 606 char *name; 607 int err; 608 609 inode = hostfs_iget(ino->i_sb); 610 if (IS_ERR(inode)) 611 goto out; 612 613 err = -ENOMEM; 614 name = dentry_name(dentry); 615 if (name) { 616 err = read_name(inode, name); 617 __putname(name); 618 } 619 if (err) { 620 iput(inode); 621 inode = (err == -ENOENT) ? NULL : ERR_PTR(err); 622 } 623 out: 624 return d_splice_alias(inode, dentry); 625 } 626 627 static int hostfs_link(struct dentry *to, struct inode *ino, 628 struct dentry *from) 629 { 630 char *from_name, *to_name; 631 int err; 632 633 if ((from_name = dentry_name(from)) == NULL) 634 return -ENOMEM; 635 to_name = dentry_name(to); 636 if (to_name == NULL) { 637 __putname(from_name); 638 return -ENOMEM; 639 } 640 err = link_file(to_name, from_name); 641 __putname(from_name); 642 __putname(to_name); 643 return err; 644 } 645 646 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 647 { 648 char *file; 649 int err; 650 651 if (append) 652 return -EPERM; 653 654 if ((file = dentry_name(dentry)) == NULL) 655 return -ENOMEM; 656 657 err = unlink_file(file); 658 __putname(file); 659 return err; 660 } 661 662 static int hostfs_symlink(struct mnt_idmap *idmap, struct inode *ino, 663 struct dentry *dentry, const char *to) 664 { 665 char *file; 666 int err; 667 668 if ((file = dentry_name(dentry)) == NULL) 669 return -ENOMEM; 670 err = make_symlink(file, to); 671 __putname(file); 672 return err; 673 } 674 675 static int hostfs_mkdir(struct mnt_idmap *idmap, struct inode *ino, 676 struct dentry *dentry, umode_t mode) 677 { 678 char *file; 679 int err; 680 681 if ((file = dentry_name(dentry)) == NULL) 682 return -ENOMEM; 683 err = do_mkdir(file, mode); 684 __putname(file); 685 return err; 686 } 687 688 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 689 { 690 char *file; 691 int err; 692 693 if ((file = dentry_name(dentry)) == NULL) 694 return -ENOMEM; 695 err = hostfs_do_rmdir(file); 696 __putname(file); 697 return err; 698 } 699 700 static int hostfs_mknod(struct mnt_idmap *idmap, struct inode *dir, 701 struct dentry *dentry, umode_t mode, dev_t dev) 702 { 703 struct inode *inode; 704 char *name; 705 int err; 706 707 inode = hostfs_iget(dir->i_sb); 708 if (IS_ERR(inode)) { 709 err = PTR_ERR(inode); 710 goto out; 711 } 712 713 err = -ENOMEM; 714 name = dentry_name(dentry); 715 if (name == NULL) 716 goto out_put; 717 718 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 719 if (err) 720 goto out_free; 721 722 err = read_name(inode, name); 723 __putname(name); 724 if (err) 725 goto out_put; 726 727 d_instantiate(dentry, inode); 728 return 0; 729 730 out_free: 731 __putname(name); 732 out_put: 733 iput(inode); 734 out: 735 return err; 736 } 737 738 static int hostfs_rename2(struct mnt_idmap *idmap, 739 struct inode *old_dir, struct dentry *old_dentry, 740 struct inode *new_dir, struct dentry *new_dentry, 741 unsigned int flags) 742 { 743 char *old_name, *new_name; 744 int err; 745 746 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 747 return -EINVAL; 748 749 old_name = dentry_name(old_dentry); 750 if (old_name == NULL) 751 return -ENOMEM; 752 new_name = dentry_name(new_dentry); 753 if (new_name == NULL) { 754 __putname(old_name); 755 return -ENOMEM; 756 } 757 if (!flags) 758 err = rename_file(old_name, new_name); 759 else 760 err = rename2_file(old_name, new_name, flags); 761 762 __putname(old_name); 763 __putname(new_name); 764 return err; 765 } 766 767 static int hostfs_permission(struct mnt_idmap *idmap, 768 struct inode *ino, int desired) 769 { 770 char *name; 771 int r = 0, w = 0, x = 0, err; 772 773 if (desired & MAY_NOT_BLOCK) 774 return -ECHILD; 775 776 if (desired & MAY_READ) r = 1; 777 if (desired & MAY_WRITE) w = 1; 778 if (desired & MAY_EXEC) x = 1; 779 name = inode_name(ino); 780 if (name == NULL) 781 return -ENOMEM; 782 783 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 784 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 785 err = 0; 786 else 787 err = access_file(name, r, w, x); 788 __putname(name); 789 if (!err) 790 err = generic_permission(&nop_mnt_idmap, ino, desired); 791 return err; 792 } 793 794 static int hostfs_setattr(struct mnt_idmap *idmap, 795 struct dentry *dentry, struct iattr *attr) 796 { 797 struct inode *inode = d_inode(dentry); 798 struct hostfs_iattr attrs; 799 char *name; 800 int err; 801 802 int fd = HOSTFS_I(inode)->fd; 803 804 err = setattr_prepare(&nop_mnt_idmap, dentry, attr); 805 if (err) 806 return err; 807 808 if (append) 809 attr->ia_valid &= ~ATTR_SIZE; 810 811 attrs.ia_valid = 0; 812 if (attr->ia_valid & ATTR_MODE) { 813 attrs.ia_valid |= HOSTFS_ATTR_MODE; 814 attrs.ia_mode = attr->ia_mode; 815 } 816 if (attr->ia_valid & ATTR_UID) { 817 attrs.ia_valid |= HOSTFS_ATTR_UID; 818 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 819 } 820 if (attr->ia_valid & ATTR_GID) { 821 attrs.ia_valid |= HOSTFS_ATTR_GID; 822 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 823 } 824 if (attr->ia_valid & ATTR_SIZE) { 825 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 826 attrs.ia_size = attr->ia_size; 827 } 828 if (attr->ia_valid & ATTR_ATIME) { 829 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 830 attrs.ia_atime = (struct hostfs_timespec) 831 { attr->ia_atime.tv_sec, attr->ia_atime.tv_nsec }; 832 } 833 if (attr->ia_valid & ATTR_MTIME) { 834 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 835 attrs.ia_mtime = (struct hostfs_timespec) 836 { attr->ia_mtime.tv_sec, attr->ia_mtime.tv_nsec }; 837 } 838 if (attr->ia_valid & ATTR_CTIME) { 839 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 840 attrs.ia_ctime = (struct hostfs_timespec) 841 { attr->ia_ctime.tv_sec, attr->ia_ctime.tv_nsec }; 842 } 843 if (attr->ia_valid & ATTR_ATIME_SET) { 844 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 845 } 846 if (attr->ia_valid & ATTR_MTIME_SET) { 847 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 848 } 849 name = dentry_name(dentry); 850 if (name == NULL) 851 return -ENOMEM; 852 err = set_attr(name, &attrs, fd); 853 __putname(name); 854 if (err) 855 return err; 856 857 if ((attr->ia_valid & ATTR_SIZE) && 858 attr->ia_size != i_size_read(inode)) 859 truncate_setsize(inode, attr->ia_size); 860 861 setattr_copy(&nop_mnt_idmap, inode, attr); 862 mark_inode_dirty(inode); 863 return 0; 864 } 865 866 static const struct inode_operations hostfs_iops = { 867 .permission = hostfs_permission, 868 .setattr = hostfs_setattr, 869 }; 870 871 static const struct inode_operations hostfs_dir_iops = { 872 .create = hostfs_create, 873 .lookup = hostfs_lookup, 874 .link = hostfs_link, 875 .unlink = hostfs_unlink, 876 .symlink = hostfs_symlink, 877 .mkdir = hostfs_mkdir, 878 .rmdir = hostfs_rmdir, 879 .mknod = hostfs_mknod, 880 .rename = hostfs_rename2, 881 .permission = hostfs_permission, 882 .setattr = hostfs_setattr, 883 }; 884 885 static const char *hostfs_get_link(struct dentry *dentry, 886 struct inode *inode, 887 struct delayed_call *done) 888 { 889 char *link; 890 if (!dentry) 891 return ERR_PTR(-ECHILD); 892 link = kmalloc(PATH_MAX, GFP_KERNEL); 893 if (link) { 894 char *path = dentry_name(dentry); 895 int err = -ENOMEM; 896 if (path) { 897 err = hostfs_do_readlink(path, link, PATH_MAX); 898 if (err == PATH_MAX) 899 err = -E2BIG; 900 __putname(path); 901 } 902 if (err < 0) { 903 kfree(link); 904 return ERR_PTR(err); 905 } 906 } else { 907 return ERR_PTR(-ENOMEM); 908 } 909 910 set_delayed_call(done, kfree_link, link); 911 return link; 912 } 913 914 static const struct inode_operations hostfs_link_iops = { 915 .get_link = hostfs_get_link, 916 }; 917 918 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 919 { 920 struct inode *root_inode; 921 char *host_root_path, *req_root = d; 922 int err; 923 924 sb->s_blocksize = 1024; 925 sb->s_blocksize_bits = 10; 926 sb->s_magic = HOSTFS_SUPER_MAGIC; 927 sb->s_op = &hostfs_sbops; 928 sb->s_d_op = &simple_dentry_operations; 929 sb->s_maxbytes = MAX_LFS_FILESIZE; 930 err = super_setup_bdi(sb); 931 if (err) 932 goto out; 933 934 /* NULL is printed as '(null)' by printf(): avoid that. */ 935 if (req_root == NULL) 936 req_root = ""; 937 938 err = -ENOMEM; 939 sb->s_fs_info = host_root_path = 940 kasprintf(GFP_KERNEL, "%s/%s", root_ino, req_root); 941 if (host_root_path == NULL) 942 goto out; 943 944 root_inode = new_inode(sb); 945 if (!root_inode) 946 goto out; 947 948 err = read_name(root_inode, host_root_path); 949 if (err) 950 goto out_put; 951 952 if (S_ISLNK(root_inode->i_mode)) { 953 char *name = follow_link(host_root_path); 954 if (IS_ERR(name)) { 955 err = PTR_ERR(name); 956 goto out_put; 957 } 958 err = read_name(root_inode, name); 959 kfree(name); 960 if (err) 961 goto out_put; 962 } 963 964 err = -ENOMEM; 965 sb->s_root = d_make_root(root_inode); 966 if (sb->s_root == NULL) 967 goto out; 968 969 return 0; 970 971 out_put: 972 iput(root_inode); 973 out: 974 return err; 975 } 976 977 static struct dentry *hostfs_read_sb(struct file_system_type *type, 978 int flags, const char *dev_name, 979 void *data) 980 { 981 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 982 } 983 984 static void hostfs_kill_sb(struct super_block *s) 985 { 986 kill_anon_super(s); 987 kfree(s->s_fs_info); 988 } 989 990 static struct file_system_type hostfs_type = { 991 .owner = THIS_MODULE, 992 .name = "hostfs", 993 .mount = hostfs_read_sb, 994 .kill_sb = hostfs_kill_sb, 995 .fs_flags = 0, 996 }; 997 MODULE_ALIAS_FS("hostfs"); 998 999 static int __init init_hostfs(void) 1000 { 1001 hostfs_inode_cache = KMEM_CACHE(hostfs_inode_info, 0); 1002 if (!hostfs_inode_cache) 1003 return -ENOMEM; 1004 return register_filesystem(&hostfs_type); 1005 } 1006 1007 static void __exit exit_hostfs(void) 1008 { 1009 unregister_filesystem(&hostfs_type); 1010 kmem_cache_destroy(hostfs_inode_cache); 1011 } 1012 1013 module_init(init_hostfs) 1014 module_exit(exit_hostfs) 1015 MODULE_LICENSE("GPL"); 1016