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 static int hostfs_d_delete(const struct dentry *dentry) 37 { 38 return 1; 39 } 40 41 static const struct dentry_operations hostfs_dentry_ops = { 42 .d_delete = hostfs_d_delete, 43 }; 44 45 /* Changed in hostfs_args before the kernel starts running */ 46 static char *root_ino = ""; 47 static int append = 0; 48 49 static const struct inode_operations hostfs_iops; 50 static const struct inode_operations hostfs_dir_iops; 51 static const struct inode_operations hostfs_link_iops; 52 53 #ifndef MODULE 54 static int __init hostfs_args(char *options, int *add) 55 { 56 char *ptr; 57 58 ptr = strchr(options, ','); 59 if (ptr != NULL) 60 *ptr++ = '\0'; 61 if (*options != '\0') 62 root_ino = options; 63 64 options = ptr; 65 while (options) { 66 ptr = strchr(options, ','); 67 if (ptr != NULL) 68 *ptr++ = '\0'; 69 if (*options != '\0') { 70 if (!strcmp(options, "append")) 71 append = 1; 72 else printf("hostfs_args - unsupported option - %s\n", 73 options); 74 } 75 options = ptr; 76 } 77 return 0; 78 } 79 80 __uml_setup("hostfs=", hostfs_args, 81 "hostfs=<root dir>,<flags>,...\n" 82 " This is used to set hostfs parameters. The root directory argument\n" 83 " is used to confine all hostfs mounts to within the specified directory\n" 84 " tree on the host. If this isn't specified, then a user inside UML can\n" 85 " mount anything on the host that's accessible to the user that's running\n" 86 " it.\n" 87 " The only flag currently supported is 'append', which specifies that all\n" 88 " files opened by hostfs will be opened in append mode.\n\n" 89 ); 90 #endif 91 92 static char *__dentry_name(struct dentry *dentry, char *name) 93 { 94 char *p = dentry_path_raw(dentry, name, PATH_MAX); 95 char *root; 96 size_t len; 97 98 root = dentry->d_sb->s_fs_info; 99 len = strlen(root); 100 if (IS_ERR(p)) { 101 __putname(name); 102 return NULL; 103 } 104 strlcpy(name, root, PATH_MAX); 105 if (len > p - name) { 106 __putname(name); 107 return NULL; 108 } 109 if (p > name + len) { 110 char *s = name + len; 111 while ((*s++ = *p++) != '\0') 112 ; 113 } 114 return name; 115 } 116 117 static char *dentry_name(struct dentry *dentry) 118 { 119 char *name = __getname(); 120 if (!name) 121 return NULL; 122 123 return __dentry_name(dentry, name); 124 } 125 126 static char *inode_name(struct inode *ino) 127 { 128 struct dentry *dentry; 129 char *name; 130 131 dentry = d_find_alias(ino); 132 if (!dentry) 133 return NULL; 134 135 name = dentry_name(dentry); 136 137 dput(dentry); 138 139 return name; 140 } 141 142 static char *follow_link(char *link) 143 { 144 int len, n; 145 char *name, *resolved, *end; 146 147 len = 64; 148 while (1) { 149 n = -ENOMEM; 150 name = kmalloc(len, GFP_KERNEL); 151 if (name == NULL) 152 goto out; 153 154 n = hostfs_do_readlink(link, name, len); 155 if (n < len) 156 break; 157 len *= 2; 158 kfree(name); 159 } 160 if (n < 0) 161 goto out_free; 162 163 if (*name == '/') 164 return name; 165 166 end = strrchr(link, '/'); 167 if (end == NULL) 168 return name; 169 170 *(end + 1) = '\0'; 171 len = strlen(link) + strlen(name) + 1; 172 173 resolved = kmalloc(len, GFP_KERNEL); 174 if (resolved == NULL) { 175 n = -ENOMEM; 176 goto out_free; 177 } 178 179 sprintf(resolved, "%s%s", link, name); 180 kfree(name); 181 kfree(link); 182 return resolved; 183 184 out_free: 185 kfree(name); 186 out: 187 return ERR_PTR(n); 188 } 189 190 static struct inode *hostfs_iget(struct super_block *sb) 191 { 192 struct inode *inode = new_inode(sb); 193 if (!inode) 194 return ERR_PTR(-ENOMEM); 195 return inode; 196 } 197 198 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 199 { 200 /* 201 * do_statfs uses struct statfs64 internally, but the linux kernel 202 * struct statfs still has 32-bit versions for most of these fields, 203 * so we convert them here 204 */ 205 int err; 206 long long f_blocks; 207 long long f_bfree; 208 long long f_bavail; 209 long long f_files; 210 long long f_ffree; 211 212 err = do_statfs(dentry->d_sb->s_fs_info, 213 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 214 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 215 &sf->f_namelen); 216 if (err) 217 return err; 218 sf->f_blocks = f_blocks; 219 sf->f_bfree = f_bfree; 220 sf->f_bavail = f_bavail; 221 sf->f_files = f_files; 222 sf->f_ffree = f_ffree; 223 sf->f_type = HOSTFS_SUPER_MAGIC; 224 return 0; 225 } 226 227 static struct inode *hostfs_alloc_inode(struct super_block *sb) 228 { 229 struct hostfs_inode_info *hi; 230 231 hi = kmalloc(sizeof(*hi), GFP_KERNEL); 232 if (hi == NULL) 233 return NULL; 234 hi->fd = -1; 235 hi->mode = 0; 236 inode_init_once(&hi->vfs_inode); 237 return &hi->vfs_inode; 238 } 239 240 static void hostfs_evict_inode(struct inode *inode) 241 { 242 truncate_inode_pages(&inode->i_data, 0); 243 clear_inode(inode); 244 if (HOSTFS_I(inode)->fd != -1) { 245 close_file(&HOSTFS_I(inode)->fd); 246 HOSTFS_I(inode)->fd = -1; 247 } 248 } 249 250 static void hostfs_i_callback(struct rcu_head *head) 251 { 252 struct inode *inode = container_of(head, struct inode, i_rcu); 253 kfree(HOSTFS_I(inode)); 254 } 255 256 static void hostfs_destroy_inode(struct inode *inode) 257 { 258 call_rcu(&inode->i_rcu, hostfs_i_callback); 259 } 260 261 static int hostfs_show_options(struct seq_file *seq, struct dentry *root) 262 { 263 const char *root_path = root->d_sb->s_fs_info; 264 size_t offset = strlen(root_ino) + 1; 265 266 if (strlen(root_path) > offset) 267 seq_printf(seq, ",%s", root_path + offset); 268 269 return 0; 270 } 271 272 static const struct super_operations hostfs_sbops = { 273 .alloc_inode = hostfs_alloc_inode, 274 .destroy_inode = hostfs_destroy_inode, 275 .evict_inode = hostfs_evict_inode, 276 .statfs = hostfs_statfs, 277 .show_options = hostfs_show_options, 278 }; 279 280 int hostfs_readdir(struct file *file, struct dir_context *ctx) 281 { 282 void *dir; 283 char *name; 284 unsigned long long next, ino; 285 int error, len; 286 unsigned int type; 287 288 name = dentry_name(file->f_path.dentry); 289 if (name == NULL) 290 return -ENOMEM; 291 dir = open_dir(name, &error); 292 __putname(name); 293 if (dir == NULL) 294 return -error; 295 next = ctx->pos; 296 while ((name = read_dir(dir, &next, &ino, &len, &type)) != NULL) { 297 if (!dir_emit(ctx, name, len, ino, type)) 298 break; 299 ctx->pos = next; 300 } 301 close_dir(dir); 302 return 0; 303 } 304 305 int hostfs_file_open(struct inode *ino, struct file *file) 306 { 307 static DEFINE_MUTEX(open_mutex); 308 char *name; 309 fmode_t mode = 0; 310 int err; 311 int r = 0, w = 0, fd; 312 313 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 314 if ((mode & HOSTFS_I(ino)->mode) == mode) 315 return 0; 316 317 mode |= HOSTFS_I(ino)->mode; 318 319 retry: 320 if (mode & FMODE_READ) 321 r = 1; 322 if (mode & FMODE_WRITE) 323 w = 1; 324 if (w) 325 r = 1; 326 327 name = dentry_name(file->f_path.dentry); 328 if (name == NULL) 329 return -ENOMEM; 330 331 fd = open_file(name, r, w, append); 332 __putname(name); 333 if (fd < 0) 334 return fd; 335 336 mutex_lock(&open_mutex); 337 /* somebody else had handled it first? */ 338 if ((mode & HOSTFS_I(ino)->mode) == mode) { 339 mutex_unlock(&open_mutex); 340 return 0; 341 } 342 if ((mode | HOSTFS_I(ino)->mode) != mode) { 343 mode |= HOSTFS_I(ino)->mode; 344 mutex_unlock(&open_mutex); 345 close_file(&fd); 346 goto retry; 347 } 348 if (HOSTFS_I(ino)->fd == -1) { 349 HOSTFS_I(ino)->fd = fd; 350 } else { 351 err = replace_file(fd, HOSTFS_I(ino)->fd); 352 close_file(&fd); 353 if (err < 0) { 354 mutex_unlock(&open_mutex); 355 return err; 356 } 357 } 358 HOSTFS_I(ino)->mode = mode; 359 mutex_unlock(&open_mutex); 360 361 return 0; 362 } 363 364 static int hostfs_file_release(struct inode *inode, struct file *file) 365 { 366 filemap_write_and_wait(inode->i_mapping); 367 368 return 0; 369 } 370 371 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 372 { 373 struct inode *inode = file->f_mapping->host; 374 int ret; 375 376 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 377 if (ret) 378 return ret; 379 380 mutex_lock(&inode->i_mutex); 381 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 382 mutex_unlock(&inode->i_mutex); 383 384 return ret; 385 } 386 387 static const struct file_operations hostfs_file_fops = { 388 .llseek = generic_file_llseek, 389 .read = do_sync_read, 390 .splice_read = generic_file_splice_read, 391 .aio_read = generic_file_aio_read, 392 .aio_write = generic_file_aio_write, 393 .write = do_sync_write, 394 .mmap = generic_file_mmap, 395 .open = hostfs_file_open, 396 .release = hostfs_file_release, 397 .fsync = hostfs_fsync, 398 }; 399 400 static const struct file_operations hostfs_dir_fops = { 401 .llseek = generic_file_llseek, 402 .iterate = hostfs_readdir, 403 .read = generic_read_dir, 404 }; 405 406 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 407 { 408 struct address_space *mapping = page->mapping; 409 struct inode *inode = mapping->host; 410 char *buffer; 411 unsigned long long base; 412 int count = PAGE_CACHE_SIZE; 413 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 414 int err; 415 416 if (page->index >= end_index) 417 count = inode->i_size & (PAGE_CACHE_SIZE-1); 418 419 buffer = kmap(page); 420 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 421 422 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 423 if (err != count) { 424 ClearPageUptodate(page); 425 goto out; 426 } 427 428 if (base > inode->i_size) 429 inode->i_size = base; 430 431 if (PageError(page)) 432 ClearPageError(page); 433 err = 0; 434 435 out: 436 kunmap(page); 437 438 unlock_page(page); 439 return err; 440 } 441 442 int hostfs_readpage(struct file *file, struct page *page) 443 { 444 char *buffer; 445 long long start; 446 int err = 0; 447 448 start = (long long) page->index << PAGE_CACHE_SHIFT; 449 buffer = kmap(page); 450 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 451 PAGE_CACHE_SIZE); 452 if (err < 0) 453 goto out; 454 455 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 456 457 flush_dcache_page(page); 458 SetPageUptodate(page); 459 if (PageError(page)) ClearPageError(page); 460 err = 0; 461 out: 462 kunmap(page); 463 unlock_page(page); 464 return err; 465 } 466 467 int hostfs_write_begin(struct file *file, struct address_space *mapping, 468 loff_t pos, unsigned len, unsigned flags, 469 struct page **pagep, void **fsdata) 470 { 471 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 472 473 *pagep = grab_cache_page_write_begin(mapping, index, flags); 474 if (!*pagep) 475 return -ENOMEM; 476 return 0; 477 } 478 479 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_CACHE_SIZE - 1); 486 int err; 487 488 buffer = kmap(page); 489 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 490 kunmap(page); 491 492 if (!PageUptodate(page) && err == PAGE_CACHE_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 page_cache_release(page); 503 504 return err; 505 } 506 507 static const struct address_space_operations hostfs_aops = { 508 .writepage = hostfs_writepage, 509 .readpage = hostfs_readpage, 510 .set_page_dirty = __set_page_dirty_nobuffers, 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; 541 542 default: 543 ino->i_op = &hostfs_iops; 544 ino->i_fop = &hostfs_file_fops; 545 ino->i_mapping->a_ops = &hostfs_aops; 546 } 547 548 ino->i_ino = st.ino; 549 ino->i_mode = st.mode; 550 set_nlink(ino, st.nlink); 551 i_uid_write(ino, st.uid); 552 i_gid_write(ino, st.gid); 553 ino->i_atime = st.atime; 554 ino->i_mtime = st.mtime; 555 ino->i_ctime = st.ctime; 556 ino->i_size = st.size; 557 ino->i_blocks = st.blocks; 558 return 0; 559 } 560 561 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 562 bool excl) 563 { 564 struct inode *inode; 565 char *name; 566 int error, fd; 567 568 inode = hostfs_iget(dir->i_sb); 569 if (IS_ERR(inode)) { 570 error = PTR_ERR(inode); 571 goto out; 572 } 573 574 error = -ENOMEM; 575 name = dentry_name(dentry); 576 if (name == NULL) 577 goto out_put; 578 579 fd = file_create(name, 580 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 581 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 582 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 583 if (fd < 0) 584 error = fd; 585 else 586 error = read_name(inode, name); 587 588 __putname(name); 589 if (error) 590 goto out_put; 591 592 HOSTFS_I(inode)->fd = fd; 593 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 594 d_instantiate(dentry, inode); 595 return 0; 596 597 out_put: 598 iput(inode); 599 out: 600 return error; 601 } 602 603 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 604 unsigned int flags) 605 { 606 struct inode *inode; 607 char *name; 608 int err; 609 610 inode = hostfs_iget(ino->i_sb); 611 if (IS_ERR(inode)) { 612 err = PTR_ERR(inode); 613 goto out; 614 } 615 616 err = -ENOMEM; 617 name = dentry_name(dentry); 618 if (name == NULL) 619 goto out_put; 620 621 err = read_name(inode, name); 622 623 __putname(name); 624 if (err == -ENOENT) { 625 iput(inode); 626 inode = NULL; 627 } 628 else if (err) 629 goto out_put; 630 631 d_add(dentry, inode); 632 return NULL; 633 634 out_put: 635 iput(inode); 636 out: 637 return ERR_PTR(err); 638 } 639 640 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 641 { 642 char *from_name, *to_name; 643 int err; 644 645 if ((from_name = dentry_name(from)) == NULL) 646 return -ENOMEM; 647 to_name = dentry_name(to); 648 if (to_name == NULL) { 649 __putname(from_name); 650 return -ENOMEM; 651 } 652 err = link_file(to_name, from_name); 653 __putname(from_name); 654 __putname(to_name); 655 return err; 656 } 657 658 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 659 { 660 char *file; 661 int err; 662 663 if (append) 664 return -EPERM; 665 666 if ((file = dentry_name(dentry)) == NULL) 667 return -ENOMEM; 668 669 err = unlink_file(file); 670 __putname(file); 671 return err; 672 } 673 674 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 675 { 676 char *file; 677 int err; 678 679 if ((file = dentry_name(dentry)) == NULL) 680 return -ENOMEM; 681 err = make_symlink(file, to); 682 __putname(file); 683 return err; 684 } 685 686 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 687 { 688 char *file; 689 int err; 690 691 if ((file = dentry_name(dentry)) == NULL) 692 return -ENOMEM; 693 err = do_mkdir(file, mode); 694 __putname(file); 695 return err; 696 } 697 698 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 699 { 700 char *file; 701 int err; 702 703 if ((file = dentry_name(dentry)) == NULL) 704 return -ENOMEM; 705 err = do_rmdir(file); 706 __putname(file); 707 return err; 708 } 709 710 static int hostfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) 711 { 712 struct inode *inode; 713 char *name; 714 int err; 715 716 inode = hostfs_iget(dir->i_sb); 717 if (IS_ERR(inode)) { 718 err = PTR_ERR(inode); 719 goto out; 720 } 721 722 err = -ENOMEM; 723 name = dentry_name(dentry); 724 if (name == NULL) 725 goto out_put; 726 727 init_special_inode(inode, mode, dev); 728 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 729 if (!err) 730 goto out_free; 731 732 err = read_name(inode, name); 733 __putname(name); 734 if (err) 735 goto out_put; 736 if (err) 737 goto out_put; 738 739 d_instantiate(dentry, inode); 740 return 0; 741 742 out_free: 743 __putname(name); 744 out_put: 745 iput(inode); 746 out: 747 return err; 748 } 749 750 int hostfs_rename(struct inode *from_ino, struct dentry *from, 751 struct inode *to_ino, struct dentry *to) 752 { 753 char *from_name, *to_name; 754 int err; 755 756 if ((from_name = dentry_name(from)) == NULL) 757 return -ENOMEM; 758 if ((to_name = dentry_name(to)) == NULL) { 759 __putname(from_name); 760 return -ENOMEM; 761 } 762 err = rename_file(from_name, to_name); 763 __putname(from_name); 764 __putname(to_name); 765 return err; 766 } 767 768 int hostfs_permission(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(ino, desired); 791 return err; 792 } 793 794 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 795 { 796 struct inode *inode = dentry->d_inode; 797 struct hostfs_iattr attrs; 798 char *name; 799 int err; 800 801 int fd = HOSTFS_I(inode)->fd; 802 803 err = inode_change_ok(inode, attr); 804 if (err) 805 return err; 806 807 if (append) 808 attr->ia_valid &= ~ATTR_SIZE; 809 810 attrs.ia_valid = 0; 811 if (attr->ia_valid & ATTR_MODE) { 812 attrs.ia_valid |= HOSTFS_ATTR_MODE; 813 attrs.ia_mode = attr->ia_mode; 814 } 815 if (attr->ia_valid & ATTR_UID) { 816 attrs.ia_valid |= HOSTFS_ATTR_UID; 817 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 818 } 819 if (attr->ia_valid & ATTR_GID) { 820 attrs.ia_valid |= HOSTFS_ATTR_GID; 821 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 822 } 823 if (attr->ia_valid & ATTR_SIZE) { 824 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 825 attrs.ia_size = attr->ia_size; 826 } 827 if (attr->ia_valid & ATTR_ATIME) { 828 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 829 attrs.ia_atime = attr->ia_atime; 830 } 831 if (attr->ia_valid & ATTR_MTIME) { 832 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 833 attrs.ia_mtime = attr->ia_mtime; 834 } 835 if (attr->ia_valid & ATTR_CTIME) { 836 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 837 attrs.ia_ctime = attr->ia_ctime; 838 } 839 if (attr->ia_valid & ATTR_ATIME_SET) { 840 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 841 } 842 if (attr->ia_valid & ATTR_MTIME_SET) { 843 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 844 } 845 name = dentry_name(dentry); 846 if (name == NULL) 847 return -ENOMEM; 848 err = set_attr(name, &attrs, fd); 849 __putname(name); 850 if (err) 851 return err; 852 853 if ((attr->ia_valid & ATTR_SIZE) && 854 attr->ia_size != i_size_read(inode)) 855 truncate_setsize(inode, attr->ia_size); 856 857 setattr_copy(inode, attr); 858 mark_inode_dirty(inode); 859 return 0; 860 } 861 862 static const struct inode_operations hostfs_iops = { 863 .permission = hostfs_permission, 864 .setattr = hostfs_setattr, 865 }; 866 867 static const struct inode_operations hostfs_dir_iops = { 868 .create = hostfs_create, 869 .lookup = hostfs_lookup, 870 .link = hostfs_link, 871 .unlink = hostfs_unlink, 872 .symlink = hostfs_symlink, 873 .mkdir = hostfs_mkdir, 874 .rmdir = hostfs_rmdir, 875 .mknod = hostfs_mknod, 876 .rename = hostfs_rename, 877 .permission = hostfs_permission, 878 .setattr = hostfs_setattr, 879 }; 880 881 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 882 { 883 char *link = __getname(); 884 if (link) { 885 char *path = dentry_name(dentry); 886 int err = -ENOMEM; 887 if (path) { 888 err = hostfs_do_readlink(path, link, PATH_MAX); 889 if (err == PATH_MAX) 890 err = -E2BIG; 891 __putname(path); 892 } 893 if (err < 0) { 894 __putname(link); 895 link = ERR_PTR(err); 896 } 897 } else { 898 link = ERR_PTR(-ENOMEM); 899 } 900 901 nd_set_link(nd, link); 902 return NULL; 903 } 904 905 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 906 { 907 char *s = nd_get_link(nd); 908 if (!IS_ERR(s)) 909 __putname(s); 910 } 911 912 static const struct inode_operations hostfs_link_iops = { 913 .readlink = generic_readlink, 914 .follow_link = hostfs_follow_link, 915 .put_link = hostfs_put_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 = &hostfs_dentry_ops; 929 sb->s_maxbytes = MAX_LFS_FILESIZE; 930 931 /* NULL is printed as <NULL> by sprintf: avoid that. */ 932 if (req_root == NULL) 933 req_root = ""; 934 935 err = -ENOMEM; 936 sb->s_fs_info = host_root_path = 937 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 938 if (host_root_path == NULL) 939 goto out; 940 941 sprintf(host_root_path, "%s/%s", root_ino, req_root); 942 943 root_inode = new_inode(sb); 944 if (!root_inode) 945 goto out; 946 947 err = read_name(root_inode, host_root_path); 948 if (err) 949 goto out_put; 950 951 if (S_ISLNK(root_inode->i_mode)) { 952 char *name = follow_link(host_root_path); 953 if (IS_ERR(name)) 954 err = PTR_ERR(name); 955 else 956 err = read_name(root_inode, name); 957 kfree(name); 958 if (err) 959 goto out_put; 960 } 961 962 err = -ENOMEM; 963 sb->s_root = d_make_root(root_inode); 964 if (sb->s_root == NULL) 965 goto out; 966 967 return 0; 968 969 out_put: 970 iput(root_inode); 971 out: 972 return err; 973 } 974 975 static struct dentry *hostfs_read_sb(struct file_system_type *type, 976 int flags, const char *dev_name, 977 void *data) 978 { 979 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 980 } 981 982 static void hostfs_kill_sb(struct super_block *s) 983 { 984 kill_anon_super(s); 985 kfree(s->s_fs_info); 986 } 987 988 static struct file_system_type hostfs_type = { 989 .owner = THIS_MODULE, 990 .name = "hostfs", 991 .mount = hostfs_read_sb, 992 .kill_sb = hostfs_kill_sb, 993 .fs_flags = 0, 994 }; 995 MODULE_ALIAS_FS("hostfs"); 996 997 static int __init init_hostfs(void) 998 { 999 return register_filesystem(&hostfs_type); 1000 } 1001 1002 static void __exit exit_hostfs(void) 1003 { 1004 unregister_filesystem(&hostfs_type); 1005 } 1006 1007 module_init(init_hostfs) 1008 module_exit(exit_hostfs) 1009 MODULE_LICENSE("GPL"); 1010