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 strlcpy(name, root, PATH_MAX); 97 if (len > p - name) { 98 __putname(name); 99 return NULL; 100 } 101 if (p > name + len) { 102 char *s = name + len; 103 while ((*s++ = *p++) != '\0') 104 ; 105 } 106 return name; 107 } 108 109 static char *dentry_name(struct dentry *dentry) 110 { 111 char *name = __getname(); 112 if (!name) 113 return NULL; 114 115 return __dentry_name(dentry, name); 116 } 117 118 static char *inode_name(struct inode *ino) 119 { 120 struct dentry *dentry; 121 char *name; 122 123 dentry = d_find_alias(ino); 124 if (!dentry) 125 return NULL; 126 127 name = dentry_name(dentry); 128 129 dput(dentry); 130 131 return name; 132 } 133 134 static char *follow_link(char *link) 135 { 136 int len, n; 137 char *name, *resolved, *end; 138 139 len = 64; 140 while (1) { 141 n = -ENOMEM; 142 name = kmalloc(len, GFP_KERNEL); 143 if (name == NULL) 144 goto out; 145 146 n = hostfs_do_readlink(link, name, len); 147 if (n < len) 148 break; 149 len *= 2; 150 kfree(name); 151 } 152 if (n < 0) 153 goto out_free; 154 155 if (*name == '/') 156 return name; 157 158 end = strrchr(link, '/'); 159 if (end == NULL) 160 return name; 161 162 *(end + 1) = '\0'; 163 len = strlen(link) + strlen(name) + 1; 164 165 resolved = kmalloc(len, GFP_KERNEL); 166 if (resolved == NULL) { 167 n = -ENOMEM; 168 goto out_free; 169 } 170 171 sprintf(resolved, "%s%s", link, name); 172 kfree(name); 173 kfree(link); 174 return resolved; 175 176 out_free: 177 kfree(name); 178 out: 179 return ERR_PTR(n); 180 } 181 182 static struct inode *hostfs_iget(struct super_block *sb) 183 { 184 struct inode *inode = new_inode(sb); 185 if (!inode) 186 return ERR_PTR(-ENOMEM); 187 return inode; 188 } 189 190 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 191 { 192 /* 193 * do_statfs uses struct statfs64 internally, but the linux kernel 194 * struct statfs still has 32-bit versions for most of these fields, 195 * so we convert them here 196 */ 197 int err; 198 long long f_blocks; 199 long long f_bfree; 200 long long f_bavail; 201 long long f_files; 202 long long f_ffree; 203 204 err = do_statfs(dentry->d_sb->s_fs_info, 205 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 206 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 207 &sf->f_namelen); 208 if (err) 209 return err; 210 sf->f_blocks = f_blocks; 211 sf->f_bfree = f_bfree; 212 sf->f_bavail = f_bavail; 213 sf->f_files = f_files; 214 sf->f_ffree = f_ffree; 215 sf->f_type = HOSTFS_SUPER_MAGIC; 216 return 0; 217 } 218 219 static struct inode *hostfs_alloc_inode(struct super_block *sb) 220 { 221 struct hostfs_inode_info *hi; 222 223 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 224 if (hi == NULL) 225 return NULL; 226 hi->fd = -1; 227 hi->mode = 0; 228 inode_init_once(&hi->vfs_inode); 229 mutex_init(&hi->open_mutex); 230 return &hi->vfs_inode; 231 } 232 233 static void hostfs_evict_inode(struct inode *inode) 234 { 235 truncate_inode_pages_final(&inode->i_data); 236 clear_inode(inode); 237 if (HOSTFS_I(inode)->fd != -1) { 238 close_file(&HOSTFS_I(inode)->fd); 239 HOSTFS_I(inode)->fd = -1; 240 } 241 } 242 243 static void hostfs_i_callback(struct rcu_head *head) 244 { 245 struct inode *inode = container_of(head, struct inode, i_rcu); 246 kfree(HOSTFS_I(inode)); 247 } 248 249 static void hostfs_destroy_inode(struct inode *inode) 250 { 251 call_rcu(&inode->i_rcu, hostfs_i_callback); 252 } 253 254 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 255 { 256 const char *root_path = root->d_sb->s_fs_info; 257 size_t offset = strlen(root_ino) + 1; 258 259 if (strlen(root_path) > offset) 260 seq_printf(seq, ",%s", root_path + offset); 261 262 return 0; 263 } 264 265 static const struct super_operations hostfs_sbops = { 266 .alloc_inode = hostfs_alloc_inode, 267 .destroy_inode = hostfs_destroy_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 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 290 if (!dir_emit(ctx, name, len, ino, type)) 291 break; 292 ctx->pos = next; 293 } 294 close_dir(dir); 295 return 0; 296 } 297 298 static int hostfs_file_open(struct inode *ino, struct file *file) 299 { 300 char *name; 301 fmode_t mode = 0; 302 int err; 303 int r = 0, w = 0, fd; 304 305 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 306 if ((mode & HOSTFS_I(ino)->mode) == mode) 307 return 0; 308 309 mode |= HOSTFS_I(ino)->mode; 310 311 retry: 312 if (mode & FMODE_READ) 313 r = 1; 314 if (mode & FMODE_WRITE) 315 w = 1; 316 if (w) 317 r = 1; 318 319 name = dentry_name(file->f_path.dentry); 320 if (name == NULL) 321 return -ENOMEM; 322 323 fd = open_file(name, r, w, append); 324 __putname(name); 325 if (fd < 0) 326 return fd; 327 328 mutex_lock(&HOSTFS_I(ino)->open_mutex); 329 /* somebody else had handled it first? */ 330 if ((mode & HOSTFS_I(ino)->mode) == mode) { 331 mutex_unlock(&HOSTFS_I(ino)->open_mutex); 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 = filemap_write_and_wait_range(inode->i_mapping, start, end); 370 if (ret) 371 return ret; 372 373 mutex_lock(&inode->i_mutex); 374 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 375 mutex_unlock(&inode->i_mutex); 376 377 return ret; 378 } 379 380 static const struct file_operations hostfs_file_fops = { 381 .llseek = generic_file_llseek, 382 .read = new_sync_read, 383 .splice_read = generic_file_splice_read, 384 .read_iter = generic_file_read_iter, 385 .write_iter = generic_file_write_iter, 386 .write = new_sync_write, 387 .mmap = generic_file_mmap, 388 .open = hostfs_file_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 = hostfs_readdir, 396 .read = generic_read_dir, 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 unsigned long long base; 405 int count = PAGE_CACHE_SIZE; 406 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 407 int err; 408 409 if (page->index >= end_index) 410 count = inode->i_size & (PAGE_CACHE_SIZE-1); 411 412 buffer = kmap(page); 413 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 414 415 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 416 if (err != count) { 417 ClearPageUptodate(page); 418 goto out; 419 } 420 421 if (base > inode->i_size) 422 inode->i_size = base; 423 424 if (PageError(page)) 425 ClearPageError(page); 426 err = 0; 427 428 out: 429 kunmap(page); 430 431 unlock_page(page); 432 return err; 433 } 434 435 static int hostfs_readpage(struct file *file, struct page *page) 436 { 437 char *buffer; 438 long long start; 439 int err = 0; 440 441 start = (long long) page->index << PAGE_CACHE_SHIFT; 442 buffer = kmap(page); 443 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 444 PAGE_CACHE_SIZE); 445 if (err < 0) 446 goto out; 447 448 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 449 450 flush_dcache_page(page); 451 SetPageUptodate(page); 452 if (PageError(page)) ClearPageError(page); 453 err = 0; 454 out: 455 kunmap(page); 456 unlock_page(page); 457 return err; 458 } 459 460 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 461 loff_t pos, unsigned len, unsigned flags, 462 struct page **pagep, void **fsdata) 463 { 464 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 465 466 *pagep = grab_cache_page_write_begin(mapping, index, flags); 467 if (!*pagep) 468 return -ENOMEM; 469 return 0; 470 } 471 472 static int hostfs_write_end(struct file *file, struct address_space *mapping, 473 loff_t pos, unsigned len, unsigned copied, 474 struct page *page, void *fsdata) 475 { 476 struct inode *inode = mapping->host; 477 void *buffer; 478 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 479 int err; 480 481 buffer = kmap(page); 482 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 483 kunmap(page); 484 485 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 486 SetPageUptodate(page); 487 488 /* 489 * If err > 0, write_file has added err to pos, so we are comparing 490 * i_size against the last byte written. 491 */ 492 if (err > 0 && (pos > inode->i_size)) 493 inode->i_size = pos; 494 unlock_page(page); 495 page_cache_release(page); 496 497 return err; 498 } 499 500 static const struct address_space_operations hostfs_aops = { 501 .writepage = hostfs_writepage, 502 .readpage = hostfs_readpage, 503 .set_page_dirty = __set_page_dirty_nobuffers, 504 .write_begin = hostfs_write_begin, 505 .write_end = hostfs_write_end, 506 }; 507 508 static int read_name(struct inode *ino, char *name) 509 { 510 dev_t rdev; 511 struct hostfs_stat st; 512 int err = stat_file(name, &st, -1); 513 if (err) 514 return err; 515 516 /* Reencode maj and min with the kernel encoding.*/ 517 rdev = MKDEV(st.maj, st.min); 518 519 switch (st.mode & S_IFMT) { 520 case S_IFLNK: 521 ino->i_op = &hostfs_link_iops; 522 break; 523 case S_IFDIR: 524 ino->i_op = &hostfs_dir_iops; 525 ino->i_fop = &hostfs_dir_fops; 526 break; 527 case S_IFCHR: 528 case S_IFBLK: 529 case S_IFIFO: 530 case S_IFSOCK: 531 init_special_inode(ino, st.mode & S_IFMT, rdev); 532 ino->i_op = &hostfs_iops; 533 break; 534 535 default: 536 ino->i_op = &hostfs_iops; 537 ino->i_fop = &hostfs_file_fops; 538 ino->i_mapping->a_ops = &hostfs_aops; 539 } 540 541 ino->i_ino = st.ino; 542 ino->i_mode = st.mode; 543 set_nlink(ino, st.nlink); 544 i_uid_write(ino, st.uid); 545 i_gid_write(ino, st.gid); 546 ino->i_atime = st.atime; 547 ino->i_mtime = st.mtime; 548 ino->i_ctime = st.ctime; 549 ino->i_size = st.size; 550 ino->i_blocks = st.blocks; 551 return 0; 552 } 553 554 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 555 bool excl) 556 { 557 struct inode *inode; 558 char *name; 559 int error, fd; 560 561 inode = hostfs_iget(dir->i_sb); 562 if (IS_ERR(inode)) { 563 error = PTR_ERR(inode); 564 goto out; 565 } 566 567 error = -ENOMEM; 568 name = dentry_name(dentry); 569 if (name == NULL) 570 goto out_put; 571 572 fd = file_create(name, 573 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 574 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 575 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 576 if (fd < 0) 577 error = fd; 578 else 579 error = read_name(inode, name); 580 581 __putname(name); 582 if (error) 583 goto out_put; 584 585 HOSTFS_I(inode)->fd = fd; 586 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 587 d_instantiate(dentry, inode); 588 return 0; 589 590 out_put: 591 iput(inode); 592 out: 593 return error; 594 } 595 596 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 597 unsigned int flags) 598 { 599 struct inode *inode; 600 char *name; 601 int err; 602 603 inode = hostfs_iget(ino->i_sb); 604 if (IS_ERR(inode)) { 605 err = PTR_ERR(inode); 606 goto out; 607 } 608 609 err = -ENOMEM; 610 name = dentry_name(dentry); 611 if (name == NULL) 612 goto out_put; 613 614 err = read_name(inode, name); 615 616 __putname(name); 617 if (err == -ENOENT) { 618 iput(inode); 619 inode = NULL; 620 } 621 else if (err) 622 goto out_put; 623 624 d_add(dentry, inode); 625 return NULL; 626 627 out_put: 628 iput(inode); 629 out: 630 return ERR_PTR(err); 631 } 632 633 static int hostfs_link(struct dentry *to, struct inode *ino, 634 struct dentry *from) 635 { 636 char *from_name, *to_name; 637 int err; 638 639 if ((from_name = dentry_name(from)) == NULL) 640 return -ENOMEM; 641 to_name = dentry_name(to); 642 if (to_name == NULL) { 643 __putname(from_name); 644 return -ENOMEM; 645 } 646 err = link_file(to_name, from_name); 647 __putname(from_name); 648 __putname(to_name); 649 return err; 650 } 651 652 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 653 { 654 char *file; 655 int err; 656 657 if (append) 658 return -EPERM; 659 660 if ((file = dentry_name(dentry)) == NULL) 661 return -ENOMEM; 662 663 err = unlink_file(file); 664 __putname(file); 665 return err; 666 } 667 668 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 669 const char *to) 670 { 671 char *file; 672 int err; 673 674 if ((file = dentry_name(dentry)) == NULL) 675 return -ENOMEM; 676 err = make_symlink(file, to); 677 __putname(file); 678 return err; 679 } 680 681 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 682 { 683 char *file; 684 int err; 685 686 if ((file = dentry_name(dentry)) == NULL) 687 return -ENOMEM; 688 err = do_mkdir(file, mode); 689 __putname(file); 690 return err; 691 } 692 693 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 694 { 695 char *file; 696 int err; 697 698 if ((file = dentry_name(dentry)) == NULL) 699 return -ENOMEM; 700 err = do_rmdir(file); 701 __putname(file); 702 return err; 703 } 704 705 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 706 { 707 struct inode *inode; 708 char *name; 709 int err; 710 711 inode = hostfs_iget(dir->i_sb); 712 if (IS_ERR(inode)) { 713 err = PTR_ERR(inode); 714 goto out; 715 } 716 717 err = -ENOMEM; 718 name = dentry_name(dentry); 719 if (name == NULL) 720 goto out_put; 721 722 init_special_inode(inode, mode, dev); 723 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 724 if (!err) 725 goto out_free; 726 727 err = read_name(inode, name); 728 __putname(name); 729 if (err) 730 goto out_put; 731 if (err) 732 goto out_put; 733 734 d_instantiate(dentry, inode); 735 return 0; 736 737 out_free: 738 __putname(name); 739 out_put: 740 iput(inode); 741 out: 742 return err; 743 } 744 745 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 746 struct inode *new_dir, struct dentry *new_dentry, 747 unsigned int flags) 748 { 749 char *old_name, *new_name; 750 int err; 751 752 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 753 return -EINVAL; 754 755 old_name = dentry_name(old_dentry); 756 if (old_name == NULL) 757 return -ENOMEM; 758 new_name = dentry_name(new_dentry); 759 if (new_name == NULL) { 760 __putname(old_name); 761 return -ENOMEM; 762 } 763 if (!flags) 764 err = rename_file(old_name, new_name); 765 else 766 err = rename2_file(old_name, new_name, flags); 767 768 __putname(old_name); 769 __putname(new_name); 770 return err; 771 } 772 773 static int hostfs_permission(struct inode *ino, int desired) 774 { 775 char *name; 776 int r = 0, w = 0, x = 0, err; 777 778 if (desired & MAY_NOT_BLOCK) 779 return -ECHILD; 780 781 if (desired & MAY_READ) r = 1; 782 if (desired & MAY_WRITE) w = 1; 783 if (desired & MAY_EXEC) x = 1; 784 name = inode_name(ino); 785 if (name == NULL) 786 return -ENOMEM; 787 788 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 789 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 790 err = 0; 791 else 792 err = access_file(name, r, w, x); 793 __putname(name); 794 if (!err) 795 err = generic_permission(ino, desired); 796 return err; 797 } 798 799 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 800 { 801 struct inode *inode = dentry->d_inode; 802 struct hostfs_iattr attrs; 803 char *name; 804 int err; 805 806 int fd = HOSTFS_I(inode)->fd; 807 808 err = inode_change_ok(inode, attr); 809 if (err) 810 return err; 811 812 if (append) 813 attr->ia_valid &= ~ATTR_SIZE; 814 815 attrs.ia_valid = 0; 816 if (attr->ia_valid & ATTR_MODE) { 817 attrs.ia_valid |= HOSTFS_ATTR_MODE; 818 attrs.ia_mode = attr->ia_mode; 819 } 820 if (attr->ia_valid & ATTR_UID) { 821 attrs.ia_valid |= HOSTFS_ATTR_UID; 822 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 823 } 824 if (attr->ia_valid & ATTR_GID) { 825 attrs.ia_valid |= HOSTFS_ATTR_GID; 826 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 827 } 828 if (attr->ia_valid & ATTR_SIZE) { 829 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 830 attrs.ia_size = attr->ia_size; 831 } 832 if (attr->ia_valid & ATTR_ATIME) { 833 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 834 attrs.ia_atime = attr->ia_atime; 835 } 836 if (attr->ia_valid & ATTR_MTIME) { 837 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 838 attrs.ia_mtime = attr->ia_mtime; 839 } 840 if (attr->ia_valid & ATTR_CTIME) { 841 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 842 attrs.ia_ctime = attr->ia_ctime; 843 } 844 if (attr->ia_valid & ATTR_ATIME_SET) { 845 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 846 } 847 if (attr->ia_valid & ATTR_MTIME_SET) { 848 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 849 } 850 name = dentry_name(dentry); 851 if (name == NULL) 852 return -ENOMEM; 853 err = set_attr(name, &attrs, fd); 854 __putname(name); 855 if (err) 856 return err; 857 858 if ((attr->ia_valid & ATTR_SIZE) && 859 attr->ia_size != i_size_read(inode)) 860 truncate_setsize(inode, attr->ia_size); 861 862 setattr_copy(inode, attr); 863 mark_inode_dirty(inode); 864 return 0; 865 } 866 867 static const struct inode_operations hostfs_iops = { 868 .permission = hostfs_permission, 869 .setattr = hostfs_setattr, 870 }; 871 872 static const struct inode_operations hostfs_dir_iops = { 873 .create = hostfs_create, 874 .lookup = hostfs_lookup, 875 .link = hostfs_link, 876 .unlink = hostfs_unlink, 877 .symlink = hostfs_symlink, 878 .mkdir = hostfs_mkdir, 879 .rmdir = hostfs_rmdir, 880 .mknod = hostfs_mknod, 881 .rename2 = hostfs_rename2, 882 .permission = hostfs_permission, 883 .setattr = hostfs_setattr, 884 }; 885 886 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 887 { 888 char *link = __getname(); 889 if (link) { 890 char *path = dentry_name(dentry); 891 int err = -ENOMEM; 892 if (path) { 893 err = hostfs_do_readlink(path, link, PATH_MAX); 894 if (err == PATH_MAX) 895 err = -E2BIG; 896 __putname(path); 897 } 898 if (err < 0) { 899 __putname(link); 900 link = ERR_PTR(err); 901 } 902 } else { 903 link = ERR_PTR(-ENOMEM); 904 } 905 906 nd_set_link(nd, link); 907 return NULL; 908 } 909 910 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 911 { 912 char *s = nd_get_link(nd); 913 if (!IS_ERR(s)) 914 __putname(s); 915 } 916 917 static const struct inode_operations hostfs_link_iops = { 918 .readlink = generic_readlink, 919 .follow_link = hostfs_follow_link, 920 .put_link = hostfs_put_link, 921 }; 922 923 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 924 { 925 struct inode *root_inode; 926 char *host_root_path, *req_root = d; 927 int err; 928 929 sb->s_blocksize = 1024; 930 sb->s_blocksize_bits = 10; 931 sb->s_magic = HOSTFS_SUPER_MAGIC; 932 sb->s_op = &hostfs_sbops; 933 sb->s_d_op = &simple_dentry_operations; 934 sb->s_maxbytes = MAX_LFS_FILESIZE; 935 936 /* NULL is printed as <NULL> by sprintf: avoid that. */ 937 if (req_root == NULL) 938 req_root = ""; 939 940 err = -ENOMEM; 941 sb->s_fs_info = host_root_path = 942 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 943 if (host_root_path == NULL) 944 goto out; 945 946 sprintf(host_root_path, "%s/%s", root_ino, req_root); 947 948 root_inode = new_inode(sb); 949 if (!root_inode) 950 goto out; 951 952 err = read_name(root_inode, host_root_path); 953 if (err) 954 goto out_put; 955 956 if (S_ISLNK(root_inode->i_mode)) { 957 char *name = follow_link(host_root_path); 958 if (IS_ERR(name)) 959 err = PTR_ERR(name); 960 else 961 err = read_name(root_inode, name); 962 kfree(name); 963 if (err) 964 goto out_put; 965 } 966 967 err = -ENOMEM; 968 sb->s_root = d_make_root(root_inode); 969 if (sb->s_root == NULL) 970 goto out; 971 972 return 0; 973 974 out_put: 975 iput(root_inode); 976 out: 977 return err; 978 } 979 980 static struct dentry *hostfs_read_sb(struct file_system_type *type, 981 int flags, const char *dev_name, 982 void *data) 983 { 984 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 985 } 986 987 static void hostfs_kill_sb(struct super_block *s) 988 { 989 kill_anon_super(s); 990 kfree(s->s_fs_info); 991 } 992 993 static struct file_system_type hostfs_type = { 994 .owner = THIS_MODULE, 995 .name = "hostfs", 996 .mount = hostfs_read_sb, 997 .kill_sb = hostfs_kill_sb, 998 .fs_flags = 0, 999 }; 1000 MODULE_ALIAS_FS("hostfs"); 1001 1002 static int __init init_hostfs(void) 1003 { 1004 return register_filesystem(&hostfs_type); 1005 } 1006 1007 static void __exit exit_hostfs(void) 1008 { 1009 unregister_filesystem(&hostfs_type); 1010 } 1011 1012 module_init(init_hostfs) 1013 module_exit(exit_hostfs) 1014 MODULE_LICENSE("GPL"); 1015