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 }; 28 29 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 30 { 31 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 32 } 33 34 #define FILE_HOSTFS_I(file) HOSTFS_I(file_inode(file)) 35 36 /* Changed in hostfs_args before the kernel starts running */ 37 static char *root_ino = ""; 38 static int append = 0; 39 40 static const struct inode_operations hostfs_iops; 41 static const struct inode_operations hostfs_dir_iops; 42 static const struct inode_operations hostfs_link_iops; 43 44 #ifndef MODULE 45 static int __init hostfs_args(char *options, int *add) 46 { 47 char *ptr; 48 49 ptr = strchr(options, ','); 50 if (ptr != NULL) 51 *ptr++ = '\0'; 52 if (*options != '\0') 53 root_ino = options; 54 55 options = ptr; 56 while (options) { 57 ptr = strchr(options, ','); 58 if (ptr != NULL) 59 *ptr++ = '\0'; 60 if (*options != '\0') { 61 if (!strcmp(options, "append")) 62 append = 1; 63 else printf("hostfs_args - unsupported option - %s\n", 64 options); 65 } 66 options = ptr; 67 } 68 return 0; 69 } 70 71 __uml_setup("hostfs=", hostfs_args, 72 "hostfs=<root dir>,<flags>,...\n" 73 " This is used to set hostfs parameters. The root directory argument\n" 74 " is used to confine all hostfs mounts to within the specified directory\n" 75 " tree on the host. If this isn't specified, then a user inside UML can\n" 76 " mount anything on the host that's accessible to the user that's running\n" 77 " it.\n" 78 " The only flag currently supported is 'append', which specifies that all\n" 79 " files opened by hostfs will be opened in append mode.\n\n" 80 ); 81 #endif 82 83 static char *__dentry_name(struct dentry *dentry, char *name) 84 { 85 char *p = dentry_path_raw(dentry, name, PATH_MAX); 86 char *root; 87 size_t len; 88 89 root = dentry->d_sb->s_fs_info; 90 len = strlen(root); 91 if (IS_ERR(p)) { 92 __putname(name); 93 return NULL; 94 } 95 strlcpy(name, root, PATH_MAX); 96 if (len > p - name) { 97 __putname(name); 98 return NULL; 99 } 100 if (p > name + len) { 101 char *s = name + len; 102 while ((*s++ = *p++) != '\0') 103 ; 104 } 105 return name; 106 } 107 108 static char *dentry_name(struct dentry *dentry) 109 { 110 char *name = __getname(); 111 if (!name) 112 return NULL; 113 114 return __dentry_name(dentry, name); 115 } 116 117 static char *inode_name(struct inode *ino) 118 { 119 struct dentry *dentry; 120 char *name; 121 122 dentry = d_find_alias(ino); 123 if (!dentry) 124 return NULL; 125 126 name = dentry_name(dentry); 127 128 dput(dentry); 129 130 return name; 131 } 132 133 static char *follow_link(char *link) 134 { 135 int len, n; 136 char *name, *resolved, *end; 137 138 len = 64; 139 while (1) { 140 n = -ENOMEM; 141 name = kmalloc(len, GFP_KERNEL); 142 if (name == NULL) 143 goto out; 144 145 n = hostfs_do_readlink(link, name, len); 146 if (n < len) 147 break; 148 len *= 2; 149 kfree(name); 150 } 151 if (n < 0) 152 goto out_free; 153 154 if (*name == '/') 155 return name; 156 157 end = strrchr(link, '/'); 158 if (end == NULL) 159 return name; 160 161 *(end + 1) = '\0'; 162 len = strlen(link) + strlen(name) + 1; 163 164 resolved = kmalloc(len, GFP_KERNEL); 165 if (resolved == NULL) { 166 n = -ENOMEM; 167 goto out_free; 168 } 169 170 sprintf(resolved, "%s%s", link, name); 171 kfree(name); 172 kfree(link); 173 return resolved; 174 175 out_free: 176 kfree(name); 177 out: 178 return ERR_PTR(n); 179 } 180 181 static struct inode *hostfs_iget(struct super_block *sb) 182 { 183 struct inode *inode = new_inode(sb); 184 if (!inode) 185 return ERR_PTR(-ENOMEM); 186 return inode; 187 } 188 189 static int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 190 { 191 /* 192 * do_statfs uses struct statfs64 internally, but the linux kernel 193 * struct statfs still has 32-bit versions for most of these fields, 194 * so we convert them here 195 */ 196 int err; 197 long long f_blocks; 198 long long f_bfree; 199 long long f_bavail; 200 long long f_files; 201 long long f_ffree; 202 203 err = do_statfs(dentry->d_sb->s_fs_info, 204 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 205 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 206 &sf->f_namelen); 207 if (err) 208 return err; 209 sf->f_blocks = f_blocks; 210 sf->f_bfree = f_bfree; 211 sf->f_bavail = f_bavail; 212 sf->f_files = f_files; 213 sf->f_ffree = f_ffree; 214 sf->f_type = HOSTFS_SUPER_MAGIC; 215 return 0; 216 } 217 218 static struct inode *hostfs_alloc_inode(struct super_block *sb) 219 { 220 struct hostfs_inode_info *hi; 221 222 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 223 if (hi == NULL) 224 return NULL; 225 hi->fd = -1; 226 hi->mode = 0; 227 inode_init_once(&hi->vfs_inode); 228 return &hi->vfs_inode; 229 } 230 231 static void hostfs_evict_inode(struct inode *inode) 232 { 233 truncate_inode_pages_final(&inode->i_data); 234 clear_inode(inode); 235 if (HOSTFS_I(inode)->fd != -1) { 236 close_file(&HOSTFS_I(inode)->fd); 237 HOSTFS_I(inode)->fd = -1; 238 } 239 } 240 241 static void hostfs_i_callback(struct rcu_head *head) 242 { 243 struct inode *inode = container_of(head, struct inode, i_rcu); 244 kfree(HOSTFS_I(inode)); 245 } 246 247 static void hostfs_destroy_inode(struct inode *inode) 248 { 249 call_rcu(&inode->i_rcu, hostfs_i_callback); 250 } 251 252 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 253 { 254 const char *root_path = root->d_sb->s_fs_info; 255 size_t offset = strlen(root_ino) + 1; 256 257 if (strlen(root_path) > offset) 258 seq_printf(seq, ",%s", root_path + offset); 259 260 return 0; 261 } 262 263 static const struct super_operations hostfs_sbops = { 264 .alloc_inode = hostfs_alloc_inode, 265 .destroy_inode = hostfs_destroy_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 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 288 if (!dir_emit(ctx, name, len, ino, type)) 289 break; 290 ctx->pos = next; 291 } 292 close_dir(dir); 293 return 0; 294 } 295 296 static int hostfs_file_open(struct inode *ino, struct file *file) 297 { 298 static DEFINE_MUTEX(open_mutex); 299 char *name; 300 fmode_t mode = 0; 301 int err; 302 int r = 0, w = 0, 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 if (mode & FMODE_READ) 312 r = 1; 313 if (mode & FMODE_WRITE) 314 w = 1; 315 if (w) 316 r = 1; 317 318 name = dentry_name(file->f_path.dentry); 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(&open_mutex); 328 /* somebody else had handled it first? */ 329 if ((mode & HOSTFS_I(ino)->mode) == mode) { 330 mutex_unlock(&open_mutex); 331 return 0; 332 } 333 if ((mode | HOSTFS_I(ino)->mode) != mode) { 334 mode |= HOSTFS_I(ino)->mode; 335 mutex_unlock(&open_mutex); 336 close_file(&fd); 337 goto retry; 338 } 339 if (HOSTFS_I(ino)->fd == -1) { 340 HOSTFS_I(ino)->fd = fd; 341 } else { 342 err = replace_file(fd, HOSTFS_I(ino)->fd); 343 close_file(&fd); 344 if (err < 0) { 345 mutex_unlock(&open_mutex); 346 return err; 347 } 348 } 349 HOSTFS_I(ino)->mode = mode; 350 mutex_unlock(&open_mutex); 351 352 return 0; 353 } 354 355 static int hostfs_file_release(struct inode *inode, struct file *file) 356 { 357 filemap_write_and_wait(inode->i_mapping); 358 359 return 0; 360 } 361 362 static int hostfs_fsync(struct file *file, loff_t start, loff_t end, 363 int datasync) 364 { 365 struct inode *inode = file->f_mapping->host; 366 int ret; 367 368 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 369 if (ret) 370 return ret; 371 372 mutex_lock(&inode->i_mutex); 373 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 374 mutex_unlock(&inode->i_mutex); 375 376 return ret; 377 } 378 379 static const struct file_operations hostfs_file_fops = { 380 .llseek = generic_file_llseek, 381 .read = new_sync_read, 382 .splice_read = generic_file_splice_read, 383 .read_iter = generic_file_read_iter, 384 .write_iter = generic_file_write_iter, 385 .write = new_sync_write, 386 .mmap = generic_file_mmap, 387 .open = hostfs_file_open, 388 .release = hostfs_file_release, 389 .fsync = hostfs_fsync, 390 }; 391 392 static const struct file_operations hostfs_dir_fops = { 393 .llseek = generic_file_llseek, 394 .iterate = hostfs_readdir, 395 .read = generic_read_dir, 396 }; 397 398 static int hostfs_writepage(struct page *page, struct writeback_control *wbc) 399 { 400 struct address_space *mapping = page->mapping; 401 struct inode *inode = mapping->host; 402 char *buffer; 403 unsigned long long base; 404 int count = PAGE_CACHE_SIZE; 405 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 406 int err; 407 408 if (page->index >= end_index) 409 count = inode->i_size & (PAGE_CACHE_SIZE-1); 410 411 buffer = kmap(page); 412 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 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 long long start; 438 int err = 0; 439 440 start = (long long) page->index << PAGE_CACHE_SHIFT; 441 buffer = kmap(page); 442 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 443 PAGE_CACHE_SIZE); 444 if (err < 0) 445 goto out; 446 447 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 448 449 flush_dcache_page(page); 450 SetPageUptodate(page); 451 if (PageError(page)) ClearPageError(page); 452 err = 0; 453 out: 454 kunmap(page); 455 unlock_page(page); 456 return err; 457 } 458 459 static int hostfs_write_begin(struct file *file, struct address_space *mapping, 460 loff_t pos, unsigned len, unsigned flags, 461 struct page **pagep, void **fsdata) 462 { 463 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 464 465 *pagep = grab_cache_page_write_begin(mapping, index, flags); 466 if (!*pagep) 467 return -ENOMEM; 468 return 0; 469 } 470 471 static int hostfs_write_end(struct file *file, struct address_space *mapping, 472 loff_t pos, unsigned len, unsigned copied, 473 struct page *page, void *fsdata) 474 { 475 struct inode *inode = mapping->host; 476 void *buffer; 477 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 478 int err; 479 480 buffer = kmap(page); 481 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 482 kunmap(page); 483 484 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 485 SetPageUptodate(page); 486 487 /* 488 * If err > 0, write_file has added err to pos, so we are comparing 489 * i_size against the last byte written. 490 */ 491 if (err > 0 && (pos > inode->i_size)) 492 inode->i_size = pos; 493 unlock_page(page); 494 page_cache_release(page); 495 496 return err; 497 } 498 499 static const struct address_space_operations hostfs_aops = { 500 .writepage = hostfs_writepage, 501 .readpage = hostfs_readpage, 502 .set_page_dirty = __set_page_dirty_nobuffers, 503 .write_begin = hostfs_write_begin, 504 .write_end = hostfs_write_end, 505 }; 506 507 static int read_name(struct inode *ino, char *name) 508 { 509 dev_t rdev; 510 struct hostfs_stat st; 511 int err = stat_file(name, &st, -1); 512 if (err) 513 return err; 514 515 /* Reencode maj and min with the kernel encoding.*/ 516 rdev = MKDEV(st.maj, st.min); 517 518 switch (st.mode & S_IFMT) { 519 case S_IFLNK: 520 ino->i_op = &hostfs_link_iops; 521 break; 522 case S_IFDIR: 523 ino->i_op = &hostfs_dir_iops; 524 ino->i_fop = &hostfs_dir_fops; 525 break; 526 case S_IFCHR: 527 case S_IFBLK: 528 case S_IFIFO: 529 case S_IFSOCK: 530 init_special_inode(ino, st.mode & S_IFMT, rdev); 531 ino->i_op = &hostfs_iops; 532 break; 533 534 default: 535 ino->i_op = &hostfs_iops; 536 ino->i_fop = &hostfs_file_fops; 537 ino->i_mapping->a_ops = &hostfs_aops; 538 } 539 540 ino->i_ino = st.ino; 541 ino->i_mode = st.mode; 542 set_nlink(ino, st.nlink); 543 i_uid_write(ino, st.uid); 544 i_gid_write(ino, st.gid); 545 ino->i_atime = st.atime; 546 ino->i_mtime = st.mtime; 547 ino->i_ctime = st.ctime; 548 ino->i_size = st.size; 549 ino->i_blocks = st.blocks; 550 return 0; 551 } 552 553 static int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 554 bool excl) 555 { 556 struct inode *inode; 557 char *name; 558 int error, fd; 559 560 inode = hostfs_iget(dir->i_sb); 561 if (IS_ERR(inode)) { 562 error = PTR_ERR(inode); 563 goto out; 564 } 565 566 error = -ENOMEM; 567 name = dentry_name(dentry); 568 if (name == NULL) 569 goto out_put; 570 571 fd = file_create(name, 572 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 573 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 574 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 575 if (fd < 0) 576 error = fd; 577 else 578 error = read_name(inode, name); 579 580 __putname(name); 581 if (error) 582 goto out_put; 583 584 HOSTFS_I(inode)->fd = fd; 585 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 586 d_instantiate(dentry, inode); 587 return 0; 588 589 out_put: 590 iput(inode); 591 out: 592 return error; 593 } 594 595 static struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 596 unsigned int flags) 597 { 598 struct inode *inode; 599 char *name; 600 int err; 601 602 inode = hostfs_iget(ino->i_sb); 603 if (IS_ERR(inode)) { 604 err = PTR_ERR(inode); 605 goto out; 606 } 607 608 err = -ENOMEM; 609 name = dentry_name(dentry); 610 if (name == NULL) 611 goto out_put; 612 613 err = read_name(inode, name); 614 615 __putname(name); 616 if (err == -ENOENT) { 617 iput(inode); 618 inode = NULL; 619 } 620 else if (err) 621 goto out_put; 622 623 d_add(dentry, inode); 624 return NULL; 625 626 out_put: 627 iput(inode); 628 out: 629 return ERR_PTR(err); 630 } 631 632 static int hostfs_link(struct dentry *to, struct inode *ino, 633 struct dentry *from) 634 { 635 char *from_name, *to_name; 636 int err; 637 638 if ((from_name = dentry_name(from)) == NULL) 639 return -ENOMEM; 640 to_name = dentry_name(to); 641 if (to_name == NULL) { 642 __putname(from_name); 643 return -ENOMEM; 644 } 645 err = link_file(to_name, from_name); 646 __putname(from_name); 647 __putname(to_name); 648 return err; 649 } 650 651 static int hostfs_unlink(struct inode *ino, struct dentry *dentry) 652 { 653 char *file; 654 int err; 655 656 if (append) 657 return -EPERM; 658 659 if ((file = dentry_name(dentry)) == NULL) 660 return -ENOMEM; 661 662 err = unlink_file(file); 663 __putname(file); 664 return err; 665 } 666 667 static int hostfs_symlink(struct inode *ino, struct dentry *dentry, 668 const char *to) 669 { 670 char *file; 671 int err; 672 673 if ((file = dentry_name(dentry)) == NULL) 674 return -ENOMEM; 675 err = make_symlink(file, to); 676 __putname(file); 677 return err; 678 } 679 680 static int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 681 { 682 char *file; 683 int err; 684 685 if ((file = dentry_name(dentry)) == NULL) 686 return -ENOMEM; 687 err = do_mkdir(file, mode); 688 __putname(file); 689 return err; 690 } 691 692 static int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 693 { 694 char *file; 695 int err; 696 697 if ((file = dentry_name(dentry)) == NULL) 698 return -ENOMEM; 699 err = do_rmdir(file); 700 __putname(file); 701 return err; 702 } 703 704 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 705 { 706 struct inode *inode; 707 char *name; 708 int err; 709 710 inode = hostfs_iget(dir->i_sb); 711 if (IS_ERR(inode)) { 712 err = PTR_ERR(inode); 713 goto out; 714 } 715 716 err = -ENOMEM; 717 name = dentry_name(dentry); 718 if (name == NULL) 719 goto out_put; 720 721 init_special_inode(inode, mode, dev); 722 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 723 if (!err) 724 goto out_free; 725 726 err = read_name(inode, name); 727 __putname(name); 728 if (err) 729 goto out_put; 730 if (err) 731 goto out_put; 732 733 d_instantiate(dentry, inode); 734 return 0; 735 736 out_free: 737 __putname(name); 738 out_put: 739 iput(inode); 740 out: 741 return err; 742 } 743 744 static int hostfs_rename2(struct inode *old_dir, struct dentry *old_dentry, 745 struct inode *new_dir, struct dentry *new_dentry, 746 unsigned int flags) 747 { 748 char *old_name, *new_name; 749 int err; 750 751 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) 752 return -EINVAL; 753 754 old_name = dentry_name(old_dentry); 755 if (old_name == NULL) 756 return -ENOMEM; 757 new_name = dentry_name(new_dentry); 758 if (new_name == NULL) { 759 __putname(old_name); 760 return -ENOMEM; 761 } 762 if (!flags) 763 err = rename_file(old_name, new_name); 764 else 765 err = rename2_file(old_name, new_name, flags); 766 767 __putname(old_name); 768 __putname(new_name); 769 return err; 770 } 771 772 static int hostfs_permission(struct inode *ino, int desired) 773 { 774 char *name; 775 int r = 0, w = 0, x = 0, err; 776 777 if (desired & MAY_NOT_BLOCK) 778 return -ECHILD; 779 780 if (desired & MAY_READ) r = 1; 781 if (desired & MAY_WRITE) w = 1; 782 if (desired & MAY_EXEC) x = 1; 783 name = inode_name(ino); 784 if (name == NULL) 785 return -ENOMEM; 786 787 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 788 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 789 err = 0; 790 else 791 err = access_file(name, r, w, x); 792 __putname(name); 793 if (!err) 794 err = generic_permission(ino, desired); 795 return err; 796 } 797 798 static int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 799 { 800 struct inode *inode = dentry->d_inode; 801 struct hostfs_iattr attrs; 802 char *name; 803 int err; 804 805 int fd = HOSTFS_I(inode)->fd; 806 807 err = inode_change_ok(inode, attr); 808 if (err) 809 return err; 810 811 if (append) 812 attr->ia_valid &= ~ATTR_SIZE; 813 814 attrs.ia_valid = 0; 815 if (attr->ia_valid & ATTR_MODE) { 816 attrs.ia_valid |= HOSTFS_ATTR_MODE; 817 attrs.ia_mode = attr->ia_mode; 818 } 819 if (attr->ia_valid & ATTR_UID) { 820 attrs.ia_valid |= HOSTFS_ATTR_UID; 821 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 822 } 823 if (attr->ia_valid & ATTR_GID) { 824 attrs.ia_valid |= HOSTFS_ATTR_GID; 825 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 826 } 827 if (attr->ia_valid & ATTR_SIZE) { 828 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 829 attrs.ia_size = attr->ia_size; 830 } 831 if (attr->ia_valid & ATTR_ATIME) { 832 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 833 attrs.ia_atime = attr->ia_atime; 834 } 835 if (attr->ia_valid & ATTR_MTIME) { 836 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 837 attrs.ia_mtime = attr->ia_mtime; 838 } 839 if (attr->ia_valid & ATTR_CTIME) { 840 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 841 attrs.ia_ctime = attr->ia_ctime; 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(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 .rename2 = hostfs_rename2, 881 .permission = hostfs_permission, 882 .setattr = hostfs_setattr, 883 }; 884 885 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 886 { 887 char *link = __getname(); 888 if (link) { 889 char *path = dentry_name(dentry); 890 int err = -ENOMEM; 891 if (path) { 892 err = hostfs_do_readlink(path, link, PATH_MAX); 893 if (err == PATH_MAX) 894 err = -E2BIG; 895 __putname(path); 896 } 897 if (err < 0) { 898 __putname(link); 899 link = ERR_PTR(err); 900 } 901 } else { 902 link = ERR_PTR(-ENOMEM); 903 } 904 905 nd_set_link(nd, link); 906 return NULL; 907 } 908 909 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 910 { 911 char *s = nd_get_link(nd); 912 if (!IS_ERR(s)) 913 __putname(s); 914 } 915 916 static const struct inode_operations hostfs_link_iops = { 917 .readlink = generic_readlink, 918 .follow_link = hostfs_follow_link, 919 .put_link = hostfs_put_link, 920 }; 921 922 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 923 { 924 struct inode *root_inode; 925 char *host_root_path, *req_root = d; 926 int err; 927 928 sb->s_blocksize = 1024; 929 sb->s_blocksize_bits = 10; 930 sb->s_magic = HOSTFS_SUPER_MAGIC; 931 sb->s_op = &hostfs_sbops; 932 sb->s_d_op = &simple_dentry_operations; 933 sb->s_maxbytes = MAX_LFS_FILESIZE; 934 935 /* NULL is printed as <NULL> by sprintf: avoid that. */ 936 if (req_root == NULL) 937 req_root = ""; 938 939 err = -ENOMEM; 940 sb->s_fs_info = host_root_path = 941 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 942 if (host_root_path == NULL) 943 goto out; 944 945 sprintf(host_root_path, "%s/%s", root_ino, req_root); 946 947 root_inode = new_inode(sb); 948 if (!root_inode) 949 goto out; 950 951 err = read_name(root_inode, host_root_path); 952 if (err) 953 goto out_put; 954 955 if (S_ISLNK(root_inode->i_mode)) { 956 char *name = follow_link(host_root_path); 957 if (IS_ERR(name)) 958 err = PTR_ERR(name); 959 else 960 err = read_name(root_inode, name); 961 kfree(name); 962 if (err) 963 goto out_put; 964 } 965 966 err = -ENOMEM; 967 sb->s_root = d_make_root(root_inode); 968 if (sb->s_root == NULL) 969 goto out; 970 971 return 0; 972 973 out_put: 974 iput(root_inode); 975 out: 976 return err; 977 } 978 979 static struct dentry *hostfs_read_sb(struct file_system_type *type, 980 int flags, const char *dev_name, 981 void *data) 982 { 983 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 984 } 985 986 static void hostfs_kill_sb(struct super_block *s) 987 { 988 kill_anon_super(s); 989 kfree(s->s_fs_info); 990 } 991 992 static struct file_system_type hostfs_type = { 993 .owner = THIS_MODULE, 994 .name = "hostfs", 995 .mount = hostfs_read_sb, 996 .kill_sb = hostfs_kill_sb, 997 .fs_flags = 0, 998 }; 999 MODULE_ALIAS_FS("hostfs"); 1000 1001 static int __init init_hostfs(void) 1002 { 1003 return register_filesystem(&hostfs_type); 1004 } 1005 1006 static void __exit exit_hostfs(void) 1007 { 1008 unregister_filesystem(&hostfs_type); 1009 } 1010 1011 module_init(init_hostfs) 1012 module_exit(exit_hostfs) 1013 MODULE_LICENSE("GPL"); 1014