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 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(&inode->i_data, 0); 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 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 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 int hostfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 363 { 364 struct inode *inode = file->f_mapping->host; 365 int ret; 366 367 ret = filemap_write_and_wait_range(inode->i_mapping, start, end); 368 if (ret) 369 return ret; 370 371 mutex_lock(&inode->i_mutex); 372 ret = fsync_file(HOSTFS_I(inode)->fd, datasync); 373 mutex_unlock(&inode->i_mutex); 374 375 return ret; 376 } 377 378 static const struct file_operations hostfs_file_fops = { 379 .llseek = generic_file_llseek, 380 .read = do_sync_read, 381 .splice_read = generic_file_splice_read, 382 .aio_read = generic_file_aio_read, 383 .aio_write = generic_file_aio_write, 384 .write = do_sync_write, 385 .mmap = generic_file_mmap, 386 .open = hostfs_file_open, 387 .release = hostfs_file_release, 388 .fsync = hostfs_fsync, 389 }; 390 391 static const struct file_operations hostfs_dir_fops = { 392 .llseek = generic_file_llseek, 393 .iterate = hostfs_readdir, 394 .read = generic_read_dir, 395 }; 396 397 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 398 { 399 struct address_space *mapping = page->mapping; 400 struct inode *inode = mapping->host; 401 char *buffer; 402 unsigned long long base; 403 int count = PAGE_CACHE_SIZE; 404 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 405 int err; 406 407 if (page->index >= end_index) 408 count = inode->i_size & (PAGE_CACHE_SIZE-1); 409 410 buffer = kmap(page); 411 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 412 413 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 414 if (err != count) { 415 ClearPageUptodate(page); 416 goto out; 417 } 418 419 if (base > inode->i_size) 420 inode->i_size = base; 421 422 if (PageError(page)) 423 ClearPageError(page); 424 err = 0; 425 426 out: 427 kunmap(page); 428 429 unlock_page(page); 430 return err; 431 } 432 433 int hostfs_readpage(struct file *file, struct page *page) 434 { 435 char *buffer; 436 long long start; 437 int err = 0; 438 439 start = (long long) page->index << PAGE_CACHE_SHIFT; 440 buffer = kmap(page); 441 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 442 PAGE_CACHE_SIZE); 443 if (err < 0) 444 goto out; 445 446 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 447 448 flush_dcache_page(page); 449 SetPageUptodate(page); 450 if (PageError(page)) ClearPageError(page); 451 err = 0; 452 out: 453 kunmap(page); 454 unlock_page(page); 455 return err; 456 } 457 458 int hostfs_write_begin(struct file *file, struct address_space *mapping, 459 loff_t pos, unsigned len, unsigned flags, 460 struct page **pagep, void **fsdata) 461 { 462 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 463 464 *pagep = grab_cache_page_write_begin(mapping, index, flags); 465 if (!*pagep) 466 return -ENOMEM; 467 return 0; 468 } 469 470 int hostfs_write_end(struct file *file, struct address_space *mapping, 471 loff_t pos, unsigned len, unsigned copied, 472 struct page *page, void *fsdata) 473 { 474 struct inode *inode = mapping->host; 475 void *buffer; 476 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 477 int err; 478 479 buffer = kmap(page); 480 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 481 kunmap(page); 482 483 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 484 SetPageUptodate(page); 485 486 /* 487 * If err > 0, write_file has added err to pos, so we are comparing 488 * i_size against the last byte written. 489 */ 490 if (err > 0 && (pos > inode->i_size)) 491 inode->i_size = pos; 492 unlock_page(page); 493 page_cache_release(page); 494 495 return err; 496 } 497 498 static const struct address_space_operations hostfs_aops = { 499 .writepage = hostfs_writepage, 500 .readpage = hostfs_readpage, 501 .set_page_dirty = __set_page_dirty_nobuffers, 502 .write_begin = hostfs_write_begin, 503 .write_end = hostfs_write_end, 504 }; 505 506 static int read_name(struct inode *ino, char *name) 507 { 508 dev_t rdev; 509 struct hostfs_stat st; 510 int err = stat_file(name, &st, -1); 511 if (err) 512 return err; 513 514 /* Reencode maj and min with the kernel encoding.*/ 515 rdev = MKDEV(st.maj, st.min); 516 517 switch (st.mode & S_IFMT) { 518 case S_IFLNK: 519 ino->i_op = &hostfs_link_iops; 520 break; 521 case S_IFDIR: 522 ino->i_op = &hostfs_dir_iops; 523 ino->i_fop = &hostfs_dir_fops; 524 break; 525 case S_IFCHR: 526 case S_IFBLK: 527 case S_IFIFO: 528 case S_IFSOCK: 529 init_special_inode(ino, st.mode & S_IFMT, rdev); 530 ino->i_op = &hostfs_iops; 531 break; 532 533 default: 534 ino->i_op = &hostfs_iops; 535 ino->i_fop = &hostfs_file_fops; 536 ino->i_mapping->a_ops = &hostfs_aops; 537 } 538 539 ino->i_ino = st.ino; 540 ino->i_mode = st.mode; 541 set_nlink(ino, st.nlink); 542 i_uid_write(ino, st.uid); 543 i_gid_write(ino, st.gid); 544 ino->i_atime = st.atime; 545 ino->i_mtime = st.mtime; 546 ino->i_ctime = st.ctime; 547 ino->i_size = st.size; 548 ino->i_blocks = st.blocks; 549 return 0; 550 } 551 552 int hostfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, 553 bool excl) 554 { 555 struct inode *inode; 556 char *name; 557 int error, fd; 558 559 inode = hostfs_iget(dir->i_sb); 560 if (IS_ERR(inode)) { 561 error = PTR_ERR(inode); 562 goto out; 563 } 564 565 error = -ENOMEM; 566 name = dentry_name(dentry); 567 if (name == NULL) 568 goto out_put; 569 570 fd = file_create(name, 571 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 572 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 573 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 574 if (fd < 0) 575 error = fd; 576 else 577 error = read_name(inode, name); 578 579 __putname(name); 580 if (error) 581 goto out_put; 582 583 HOSTFS_I(inode)->fd = fd; 584 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 585 d_instantiate(dentry, inode); 586 return 0; 587 588 out_put: 589 iput(inode); 590 out: 591 return error; 592 } 593 594 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 595 unsigned int flags) 596 { 597 struct inode *inode; 598 char *name; 599 int err; 600 601 inode = hostfs_iget(ino->i_sb); 602 if (IS_ERR(inode)) { 603 err = PTR_ERR(inode); 604 goto out; 605 } 606 607 err = -ENOMEM; 608 name = dentry_name(dentry); 609 if (name == NULL) 610 goto out_put; 611 612 err = read_name(inode, name); 613 614 __putname(name); 615 if (err == -ENOENT) { 616 iput(inode); 617 inode = NULL; 618 } 619 else if (err) 620 goto out_put; 621 622 d_add(dentry, inode); 623 return NULL; 624 625 out_put: 626 iput(inode); 627 out: 628 return ERR_PTR(err); 629 } 630 631 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 632 { 633 char *from_name, *to_name; 634 int err; 635 636 if ((from_name = dentry_name(from)) == NULL) 637 return -ENOMEM; 638 to_name = dentry_name(to); 639 if (to_name == NULL) { 640 __putname(from_name); 641 return -ENOMEM; 642 } 643 err = link_file(to_name, from_name); 644 __putname(from_name); 645 __putname(to_name); 646 return err; 647 } 648 649 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 650 { 651 char *file; 652 int err; 653 654 if (append) 655 return -EPERM; 656 657 if ((file = dentry_name(dentry)) == NULL) 658 return -ENOMEM; 659 660 err = unlink_file(file); 661 __putname(file); 662 return err; 663 } 664 665 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 666 { 667 char *file; 668 int err; 669 670 if ((file = dentry_name(dentry)) == NULL) 671 return -ENOMEM; 672 err = make_symlink(file, to); 673 __putname(file); 674 return err; 675 } 676 677 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, umode_t mode) 678 { 679 char *file; 680 int err; 681 682 if ((file = dentry_name(dentry)) == NULL) 683 return -ENOMEM; 684 err = do_mkdir(file, mode); 685 __putname(file); 686 return err; 687 } 688 689 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 690 { 691 char *file; 692 int err; 693 694 if ((file = dentry_name(dentry)) == NULL) 695 return -ENOMEM; 696 err = do_rmdir(file); 697 __putname(file); 698 return err; 699 } 700 701 static int hostfs_mknod(struct inode *dir, 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 init_special_inode(inode, mode, dev); 719 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 720 if (!err) 721 goto out_free; 722 723 err = read_name(inode, name); 724 __putname(name); 725 if (err) 726 goto out_put; 727 if (err) 728 goto out_put; 729 730 d_instantiate(dentry, inode); 731 return 0; 732 733 out_free: 734 __putname(name); 735 out_put: 736 iput(inode); 737 out: 738 return err; 739 } 740 741 int hostfs_rename(struct inode *from_ino, struct dentry *from, 742 struct inode *to_ino, struct dentry *to) 743 { 744 char *from_name, *to_name; 745 int err; 746 747 if ((from_name = dentry_name(from)) == NULL) 748 return -ENOMEM; 749 if ((to_name = dentry_name(to)) == NULL) { 750 __putname(from_name); 751 return -ENOMEM; 752 } 753 err = rename_file(from_name, to_name); 754 __putname(from_name); 755 __putname(to_name); 756 return err; 757 } 758 759 int hostfs_permission(struct inode *ino, int desired) 760 { 761 char *name; 762 int r = 0, w = 0, x = 0, err; 763 764 if (desired & MAY_NOT_BLOCK) 765 return -ECHILD; 766 767 if (desired & MAY_READ) r = 1; 768 if (desired & MAY_WRITE) w = 1; 769 if (desired & MAY_EXEC) x = 1; 770 name = inode_name(ino); 771 if (name == NULL) 772 return -ENOMEM; 773 774 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 775 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 776 err = 0; 777 else 778 err = access_file(name, r, w, x); 779 __putname(name); 780 if (!err) 781 err = generic_permission(ino, desired); 782 return err; 783 } 784 785 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 786 { 787 struct inode *inode = dentry->d_inode; 788 struct hostfs_iattr attrs; 789 char *name; 790 int err; 791 792 int fd = HOSTFS_I(inode)->fd; 793 794 err = inode_change_ok(inode, attr); 795 if (err) 796 return err; 797 798 if (append) 799 attr->ia_valid &= ~ATTR_SIZE; 800 801 attrs.ia_valid = 0; 802 if (attr->ia_valid & ATTR_MODE) { 803 attrs.ia_valid |= HOSTFS_ATTR_MODE; 804 attrs.ia_mode = attr->ia_mode; 805 } 806 if (attr->ia_valid & ATTR_UID) { 807 attrs.ia_valid |= HOSTFS_ATTR_UID; 808 attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); 809 } 810 if (attr->ia_valid & ATTR_GID) { 811 attrs.ia_valid |= HOSTFS_ATTR_GID; 812 attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); 813 } 814 if (attr->ia_valid & ATTR_SIZE) { 815 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 816 attrs.ia_size = attr->ia_size; 817 } 818 if (attr->ia_valid & ATTR_ATIME) { 819 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 820 attrs.ia_atime = attr->ia_atime; 821 } 822 if (attr->ia_valid & ATTR_MTIME) { 823 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 824 attrs.ia_mtime = attr->ia_mtime; 825 } 826 if (attr->ia_valid & ATTR_CTIME) { 827 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 828 attrs.ia_ctime = attr->ia_ctime; 829 } 830 if (attr->ia_valid & ATTR_ATIME_SET) { 831 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 832 } 833 if (attr->ia_valid & ATTR_MTIME_SET) { 834 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 835 } 836 name = dentry_name(dentry); 837 if (name == NULL) 838 return -ENOMEM; 839 err = set_attr(name, &attrs, fd); 840 __putname(name); 841 if (err) 842 return err; 843 844 if ((attr->ia_valid & ATTR_SIZE) && 845 attr->ia_size != i_size_read(inode)) 846 truncate_setsize(inode, attr->ia_size); 847 848 setattr_copy(inode, attr); 849 mark_inode_dirty(inode); 850 return 0; 851 } 852 853 static const struct inode_operations hostfs_iops = { 854 .permission = hostfs_permission, 855 .setattr = hostfs_setattr, 856 }; 857 858 static const struct inode_operations hostfs_dir_iops = { 859 .create = hostfs_create, 860 .lookup = hostfs_lookup, 861 .link = hostfs_link, 862 .unlink = hostfs_unlink, 863 .symlink = hostfs_symlink, 864 .mkdir = hostfs_mkdir, 865 .rmdir = hostfs_rmdir, 866 .mknod = hostfs_mknod, 867 .rename = hostfs_rename, 868 .permission = hostfs_permission, 869 .setattr = hostfs_setattr, 870 }; 871 872 static void *hostfs_follow_link(struct dentry *dentry, struct nameidata *nd) 873 { 874 char *link = __getname(); 875 if (link) { 876 char *path = dentry_name(dentry); 877 int err = -ENOMEM; 878 if (path) { 879 err = hostfs_do_readlink(path, link, PATH_MAX); 880 if (err == PATH_MAX) 881 err = -E2BIG; 882 __putname(path); 883 } 884 if (err < 0) { 885 __putname(link); 886 link = ERR_PTR(err); 887 } 888 } else { 889 link = ERR_PTR(-ENOMEM); 890 } 891 892 nd_set_link(nd, link); 893 return NULL; 894 } 895 896 static void hostfs_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 897 { 898 char *s = nd_get_link(nd); 899 if (!IS_ERR(s)) 900 __putname(s); 901 } 902 903 static const struct inode_operations hostfs_link_iops = { 904 .readlink = generic_readlink, 905 .follow_link = hostfs_follow_link, 906 .put_link = hostfs_put_link, 907 }; 908 909 static int hostfs_fill_sb_common(struct super_block *sb, void *d, int silent) 910 { 911 struct inode *root_inode; 912 char *host_root_path, *req_root = d; 913 int err; 914 915 sb->s_blocksize = 1024; 916 sb->s_blocksize_bits = 10; 917 sb->s_magic = HOSTFS_SUPER_MAGIC; 918 sb->s_op = &hostfs_sbops; 919 sb->s_d_op = &simple_dentry_operations; 920 sb->s_maxbytes = MAX_LFS_FILESIZE; 921 922 /* NULL is printed as <NULL> by sprintf: avoid that. */ 923 if (req_root == NULL) 924 req_root = ""; 925 926 err = -ENOMEM; 927 sb->s_fs_info = host_root_path = 928 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 929 if (host_root_path == NULL) 930 goto out; 931 932 sprintf(host_root_path, "%s/%s", root_ino, req_root); 933 934 root_inode = new_inode(sb); 935 if (!root_inode) 936 goto out; 937 938 err = read_name(root_inode, host_root_path); 939 if (err) 940 goto out_put; 941 942 if (S_ISLNK(root_inode->i_mode)) { 943 char *name = follow_link(host_root_path); 944 if (IS_ERR(name)) 945 err = PTR_ERR(name); 946 else 947 err = read_name(root_inode, name); 948 kfree(name); 949 if (err) 950 goto out_put; 951 } 952 953 err = -ENOMEM; 954 sb->s_root = d_make_root(root_inode); 955 if (sb->s_root == NULL) 956 goto out; 957 958 return 0; 959 960 out_put: 961 iput(root_inode); 962 out: 963 return err; 964 } 965 966 static struct dentry *hostfs_read_sb(struct file_system_type *type, 967 int flags, const char *dev_name, 968 void *data) 969 { 970 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 971 } 972 973 static void hostfs_kill_sb(struct super_block *s) 974 { 975 kill_anon_super(s); 976 kfree(s->s_fs_info); 977 } 978 979 static struct file_system_type hostfs_type = { 980 .owner = THIS_MODULE, 981 .name = "hostfs", 982 .mount = hostfs_read_sb, 983 .kill_sb = hostfs_kill_sb, 984 .fs_flags = 0, 985 }; 986 MODULE_ALIAS_FS("hostfs"); 987 988 static int __init init_hostfs(void) 989 { 990 return register_filesystem(&hostfs_type); 991 } 992 993 static void __exit exit_hostfs(void) 994 { 995 unregister_filesystem(&hostfs_type); 996 } 997 998 module_init(init_hostfs) 999 module_exit(exit_hostfs) 1000 MODULE_LICENSE("GPL"); 1001