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/module.h> 11 #include <linux/mm.h> 12 #include <linux/pagemap.h> 13 #include <linux/statfs.h> 14 #include <linux/slab.h> 15 #include <linux/seq_file.h> 16 #include <linux/mount.h> 17 #include <linux/namei.h> 18 #include "hostfs.h" 19 #include "init.h" 20 #include "kern.h" 21 22 struct hostfs_inode_info { 23 int fd; 24 fmode_t mode; 25 struct inode vfs_inode; 26 }; 27 28 static inline struct hostfs_inode_info *HOSTFS_I(struct inode *inode) 29 { 30 return list_entry(inode, struct hostfs_inode_info, vfs_inode); 31 } 32 33 #define FILE_HOSTFS_I(file) HOSTFS_I((file)->f_path.dentry->d_inode) 34 35 static int hostfs_d_delete(struct dentry *dentry) 36 { 37 return 1; 38 } 39 40 static const struct dentry_operations hostfs_dentry_ops = { 41 .d_delete = hostfs_d_delete, 42 }; 43 44 /* Changed in hostfs_args before the kernel starts running */ 45 static char *root_ino = ""; 46 static int append = 0; 47 48 #define HOSTFS_SUPER_MAGIC 0x00c0ffee 49 50 static const struct inode_operations hostfs_iops; 51 static const struct inode_operations hostfs_dir_iops; 52 static const struct inode_operations hostfs_link_iops; 53 54 #ifndef MODULE 55 static int __init hostfs_args(char *options, int *add) 56 { 57 char *ptr; 58 59 ptr = strchr(options, ','); 60 if (ptr != NULL) 61 *ptr++ = '\0'; 62 if (*options != '\0') 63 root_ino = options; 64 65 options = ptr; 66 while (options) { 67 ptr = strchr(options, ','); 68 if (ptr != NULL) 69 *ptr++ = '\0'; 70 if (*options != '\0') { 71 if (!strcmp(options, "append")) 72 append = 1; 73 else printf("hostfs_args - unsupported option - %s\n", 74 options); 75 } 76 options = ptr; 77 } 78 return 0; 79 } 80 81 __uml_setup("hostfs=", hostfs_args, 82 "hostfs=<root dir>,<flags>,...\n" 83 " This is used to set hostfs parameters. The root directory argument\n" 84 " is used to confine all hostfs mounts to within the specified directory\n" 85 " tree on the host. If this isn't specified, then a user inside UML can\n" 86 " mount anything on the host that's accessible to the user that's running\n" 87 " it.\n" 88 " The only flag currently supported is 'append', which specifies that all\n" 89 " files opened by hostfs will be opened in append mode.\n\n" 90 ); 91 #endif 92 93 static char *__dentry_name(struct dentry *dentry, char *name) 94 { 95 char *p = __dentry_path(dentry, name, PATH_MAX); 96 char *root; 97 size_t len; 98 99 spin_unlock(&dcache_lock); 100 101 root = dentry->d_sb->s_fs_info; 102 len = strlen(root); 103 if (IS_ERR(p)) { 104 __putname(name); 105 return NULL; 106 } 107 strlcpy(name, root, PATH_MAX); 108 if (len > p - name) { 109 __putname(name); 110 return NULL; 111 } 112 if (p > name + len) { 113 char *s = name + len; 114 while ((*s++ = *p++) != '\0') 115 ; 116 } 117 return name; 118 } 119 120 static char *dentry_name(struct dentry *dentry) 121 { 122 char *name = __getname(); 123 if (!name) 124 return NULL; 125 126 spin_lock(&dcache_lock); 127 return __dentry_name(dentry, name); /* will unlock */ 128 } 129 130 static char *inode_name(struct inode *ino) 131 { 132 struct dentry *dentry; 133 char *name = __getname(); 134 if (!name) 135 return NULL; 136 137 spin_lock(&dcache_lock); 138 if (list_empty(&ino->i_dentry)) { 139 spin_unlock(&dcache_lock); 140 __putname(name); 141 return NULL; 142 } 143 dentry = list_first_entry(&ino->i_dentry, struct dentry, d_alias); 144 return __dentry_name(dentry, name); /* will unlock */ 145 } 146 147 static char *follow_link(char *link) 148 { 149 int len, n; 150 char *name, *resolved, *end; 151 152 len = 64; 153 while (1) { 154 n = -ENOMEM; 155 name = kmalloc(len, GFP_KERNEL); 156 if (name == NULL) 157 goto out; 158 159 n = hostfs_do_readlink(link, name, len); 160 if (n < len) 161 break; 162 len *= 2; 163 kfree(name); 164 } 165 if (n < 0) 166 goto out_free; 167 168 if (*name == '/') 169 return name; 170 171 end = strrchr(link, '/'); 172 if (end == NULL) 173 return name; 174 175 *(end + 1) = '\0'; 176 len = strlen(link) + strlen(name) + 1; 177 178 resolved = kmalloc(len, GFP_KERNEL); 179 if (resolved == NULL) { 180 n = -ENOMEM; 181 goto out_free; 182 } 183 184 sprintf(resolved, "%s%s", link, name); 185 kfree(name); 186 kfree(link); 187 return resolved; 188 189 out_free: 190 kfree(name); 191 out: 192 return ERR_PTR(n); 193 } 194 195 static struct inode *hostfs_iget(struct super_block *sb) 196 { 197 struct inode *inode = new_inode(sb); 198 if (!inode) 199 return ERR_PTR(-ENOMEM); 200 return inode; 201 } 202 203 int hostfs_statfs(struct dentry *dentry, struct kstatfs *sf) 204 { 205 /* 206 * do_statfs uses struct statfs64 internally, but the linux kernel 207 * struct statfs still has 32-bit versions for most of these fields, 208 * so we convert them here 209 */ 210 int err; 211 long long f_blocks; 212 long long f_bfree; 213 long long f_bavail; 214 long long f_files; 215 long long f_ffree; 216 217 err = do_statfs(dentry->d_sb->s_fs_info, 218 &sf->f_bsize, &f_blocks, &f_bfree, &f_bavail, &f_files, 219 &f_ffree, &sf->f_fsid, sizeof(sf->f_fsid), 220 &sf->f_namelen); 221 if (err) 222 return err; 223 sf->f_blocks = f_blocks; 224 sf->f_bfree = f_bfree; 225 sf->f_bavail = f_bavail; 226 sf->f_files = f_files; 227 sf->f_ffree = f_ffree; 228 sf->f_type = HOSTFS_SUPER_MAGIC; 229 return 0; 230 } 231 232 static struct inode *hostfs_alloc_inode(struct super_block *sb) 233 { 234 struct hostfs_inode_info *hi; 235 236 hi = kzalloc(sizeof(*hi), GFP_KERNEL); 237 if (hi == NULL) 238 return NULL; 239 hi->fd = -1; 240 inode_init_once(&hi->vfs_inode); 241 return &hi->vfs_inode; 242 } 243 244 static void hostfs_evict_inode(struct inode *inode) 245 { 246 truncate_inode_pages(&inode->i_data, 0); 247 end_writeback(inode); 248 if (HOSTFS_I(inode)->fd != -1) { 249 close_file(&HOSTFS_I(inode)->fd); 250 HOSTFS_I(inode)->fd = -1; 251 } 252 } 253 254 static void hostfs_destroy_inode(struct inode *inode) 255 { 256 kfree(HOSTFS_I(inode)); 257 } 258 259 static int hostfs_show_options(struct seq_file *seq, struct vfsmount *vfs) 260 { 261 const char *root_path = vfs->mnt_sb->s_fs_info; 262 size_t offset = strlen(root_ino) + 1; 263 264 if (strlen(root_path) > offset) 265 seq_printf(seq, ",%s", root_path + offset); 266 267 return 0; 268 } 269 270 static const struct super_operations hostfs_sbops = { 271 .alloc_inode = hostfs_alloc_inode, 272 .destroy_inode = hostfs_destroy_inode, 273 .evict_inode = hostfs_evict_inode, 274 .statfs = hostfs_statfs, 275 .show_options = hostfs_show_options, 276 }; 277 278 int hostfs_readdir(struct file *file, void *ent, filldir_t filldir) 279 { 280 void *dir; 281 char *name; 282 unsigned long long next, ino; 283 int error, len; 284 285 name = dentry_name(file->f_path.dentry); 286 if (name == NULL) 287 return -ENOMEM; 288 dir = open_dir(name, &error); 289 __putname(name); 290 if (dir == NULL) 291 return -error; 292 next = file->f_pos; 293 while ((name = read_dir(dir, &next, &ino, &len)) != NULL) { 294 error = (*filldir)(ent, name, len, file->f_pos, 295 ino, DT_UNKNOWN); 296 if (error) break; 297 file->f_pos = next; 298 } 299 close_dir(dir); 300 return 0; 301 } 302 303 int hostfs_file_open(struct inode *ino, struct file *file) 304 { 305 static DEFINE_MUTEX(open_mutex); 306 char *name; 307 fmode_t mode = 0; 308 int err; 309 int r = 0, w = 0, fd; 310 311 mode = file->f_mode & (FMODE_READ | FMODE_WRITE); 312 if ((mode & HOSTFS_I(ino)->mode) == mode) 313 return 0; 314 315 mode |= HOSTFS_I(ino)->mode; 316 317 retry: 318 if (mode & FMODE_READ) 319 r = 1; 320 if (mode & FMODE_WRITE) 321 w = 1; 322 if (w) 323 r = 1; 324 325 name = dentry_name(file->f_path.dentry); 326 if (name == NULL) 327 return -ENOMEM; 328 329 fd = open_file(name, r, w, append); 330 __putname(name); 331 if (fd < 0) 332 return fd; 333 334 mutex_lock(&open_mutex); 335 /* somebody else had handled it first? */ 336 if ((mode & HOSTFS_I(ino)->mode) == mode) { 337 mutex_unlock(&open_mutex); 338 return 0; 339 } 340 if ((mode | HOSTFS_I(ino)->mode) != mode) { 341 mode |= HOSTFS_I(ino)->mode; 342 mutex_unlock(&open_mutex); 343 close_file(&fd); 344 goto retry; 345 } 346 if (HOSTFS_I(ino)->fd == -1) { 347 HOSTFS_I(ino)->fd = fd; 348 } else { 349 err = replace_file(fd, HOSTFS_I(ino)->fd); 350 close_file(&fd); 351 if (err < 0) { 352 mutex_unlock(&open_mutex); 353 return err; 354 } 355 } 356 HOSTFS_I(ino)->mode = mode; 357 mutex_unlock(&open_mutex); 358 359 return 0; 360 } 361 362 int hostfs_fsync(struct file *file, int datasync) 363 { 364 return fsync_file(HOSTFS_I(file->f_mapping->host)->fd, datasync); 365 } 366 367 static const struct file_operations hostfs_file_fops = { 368 .llseek = generic_file_llseek, 369 .read = do_sync_read, 370 .splice_read = generic_file_splice_read, 371 .aio_read = generic_file_aio_read, 372 .aio_write = generic_file_aio_write, 373 .write = do_sync_write, 374 .mmap = generic_file_mmap, 375 .open = hostfs_file_open, 376 .release = NULL, 377 .fsync = hostfs_fsync, 378 }; 379 380 static const struct file_operations hostfs_dir_fops = { 381 .llseek = generic_file_llseek, 382 .readdir = hostfs_readdir, 383 .read = generic_read_dir, 384 }; 385 386 int hostfs_writepage(struct page *page, struct writeback_control *wbc) 387 { 388 struct address_space *mapping = page->mapping; 389 struct inode *inode = mapping->host; 390 char *buffer; 391 unsigned long long base; 392 int count = PAGE_CACHE_SIZE; 393 int end_index = inode->i_size >> PAGE_CACHE_SHIFT; 394 int err; 395 396 if (page->index >= end_index) 397 count = inode->i_size & (PAGE_CACHE_SIZE-1); 398 399 buffer = kmap(page); 400 base = ((unsigned long long) page->index) << PAGE_CACHE_SHIFT; 401 402 err = write_file(HOSTFS_I(inode)->fd, &base, buffer, count); 403 if (err != count) { 404 ClearPageUptodate(page); 405 goto out; 406 } 407 408 if (base > inode->i_size) 409 inode->i_size = base; 410 411 if (PageError(page)) 412 ClearPageError(page); 413 err = 0; 414 415 out: 416 kunmap(page); 417 418 unlock_page(page); 419 return err; 420 } 421 422 int hostfs_readpage(struct file *file, struct page *page) 423 { 424 char *buffer; 425 long long start; 426 int err = 0; 427 428 start = (long long) page->index << PAGE_CACHE_SHIFT; 429 buffer = kmap(page); 430 err = read_file(FILE_HOSTFS_I(file)->fd, &start, buffer, 431 PAGE_CACHE_SIZE); 432 if (err < 0) 433 goto out; 434 435 memset(&buffer[err], 0, PAGE_CACHE_SIZE - err); 436 437 flush_dcache_page(page); 438 SetPageUptodate(page); 439 if (PageError(page)) ClearPageError(page); 440 err = 0; 441 out: 442 kunmap(page); 443 unlock_page(page); 444 return err; 445 } 446 447 int hostfs_write_begin(struct file *file, struct address_space *mapping, 448 loff_t pos, unsigned len, unsigned flags, 449 struct page **pagep, void **fsdata) 450 { 451 pgoff_t index = pos >> PAGE_CACHE_SHIFT; 452 453 *pagep = grab_cache_page_write_begin(mapping, index, flags); 454 if (!*pagep) 455 return -ENOMEM; 456 return 0; 457 } 458 459 int hostfs_write_end(struct file *file, struct address_space *mapping, 460 loff_t pos, unsigned len, unsigned copied, 461 struct page *page, void *fsdata) 462 { 463 struct inode *inode = mapping->host; 464 void *buffer; 465 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 466 int err; 467 468 buffer = kmap(page); 469 err = write_file(FILE_HOSTFS_I(file)->fd, &pos, buffer + from, copied); 470 kunmap(page); 471 472 if (!PageUptodate(page) && err == PAGE_CACHE_SIZE) 473 SetPageUptodate(page); 474 475 /* 476 * If err > 0, write_file has added err to pos, so we are comparing 477 * i_size against the last byte written. 478 */ 479 if (err > 0 && (pos > inode->i_size)) 480 inode->i_size = pos; 481 unlock_page(page); 482 page_cache_release(page); 483 484 return err; 485 } 486 487 static const struct address_space_operations hostfs_aops = { 488 .writepage = hostfs_writepage, 489 .readpage = hostfs_readpage, 490 .set_page_dirty = __set_page_dirty_nobuffers, 491 .write_begin = hostfs_write_begin, 492 .write_end = hostfs_write_end, 493 }; 494 495 static int read_name(struct inode *ino, char *name) 496 { 497 dev_t rdev; 498 struct hostfs_stat st; 499 int err = stat_file(name, &st, -1); 500 if (err) 501 return err; 502 503 /* Reencode maj and min with the kernel encoding.*/ 504 rdev = MKDEV(st.maj, st.min); 505 506 switch (st.mode & S_IFMT) { 507 case S_IFLNK: 508 ino->i_op = &hostfs_link_iops; 509 break; 510 case S_IFDIR: 511 ino->i_op = &hostfs_dir_iops; 512 ino->i_fop = &hostfs_dir_fops; 513 break; 514 case S_IFCHR: 515 case S_IFBLK: 516 case S_IFIFO: 517 case S_IFSOCK: 518 init_special_inode(ino, st.mode & S_IFMT, rdev); 519 ino->i_op = &hostfs_iops; 520 break; 521 522 default: 523 ino->i_op = &hostfs_iops; 524 ino->i_fop = &hostfs_file_fops; 525 ino->i_mapping->a_ops = &hostfs_aops; 526 } 527 528 ino->i_ino = st.ino; 529 ino->i_mode = st.mode; 530 ino->i_nlink = st.nlink; 531 ino->i_uid = st.uid; 532 ino->i_gid = st.gid; 533 ino->i_atime = st.atime; 534 ino->i_mtime = st.mtime; 535 ino->i_ctime = st.ctime; 536 ino->i_size = st.size; 537 ino->i_blocks = st.blocks; 538 return 0; 539 } 540 541 int hostfs_create(struct inode *dir, struct dentry *dentry, int mode, 542 struct nameidata *nd) 543 { 544 struct inode *inode; 545 char *name; 546 int error, fd; 547 548 inode = hostfs_iget(dir->i_sb); 549 if (IS_ERR(inode)) { 550 error = PTR_ERR(inode); 551 goto out; 552 } 553 554 error = -ENOMEM; 555 name = dentry_name(dentry); 556 if (name == NULL) 557 goto out_put; 558 559 fd = file_create(name, 560 mode & S_IRUSR, mode & S_IWUSR, mode & S_IXUSR, 561 mode & S_IRGRP, mode & S_IWGRP, mode & S_IXGRP, 562 mode & S_IROTH, mode & S_IWOTH, mode & S_IXOTH); 563 if (fd < 0) 564 error = fd; 565 else 566 error = read_name(inode, name); 567 568 __putname(name); 569 if (error) 570 goto out_put; 571 572 HOSTFS_I(inode)->fd = fd; 573 HOSTFS_I(inode)->mode = FMODE_READ | FMODE_WRITE; 574 d_instantiate(dentry, inode); 575 return 0; 576 577 out_put: 578 iput(inode); 579 out: 580 return error; 581 } 582 583 struct dentry *hostfs_lookup(struct inode *ino, struct dentry *dentry, 584 struct nameidata *nd) 585 { 586 struct inode *inode; 587 char *name; 588 int err; 589 590 inode = hostfs_iget(ino->i_sb); 591 if (IS_ERR(inode)) { 592 err = PTR_ERR(inode); 593 goto out; 594 } 595 596 err = -ENOMEM; 597 name = dentry_name(dentry); 598 if (name == NULL) 599 goto out_put; 600 601 err = read_name(inode, name); 602 603 __putname(name); 604 if (err == -ENOENT) { 605 iput(inode); 606 inode = NULL; 607 } 608 else if (err) 609 goto out_put; 610 611 d_add(dentry, inode); 612 dentry->d_op = &hostfs_dentry_ops; 613 return NULL; 614 615 out_put: 616 iput(inode); 617 out: 618 return ERR_PTR(err); 619 } 620 621 int hostfs_link(struct dentry *to, struct inode *ino, struct dentry *from) 622 { 623 char *from_name, *to_name; 624 int err; 625 626 if ((from_name = dentry_name(from)) == NULL) 627 return -ENOMEM; 628 to_name = dentry_name(to); 629 if (to_name == NULL) { 630 __putname(from_name); 631 return -ENOMEM; 632 } 633 err = link_file(to_name, from_name); 634 __putname(from_name); 635 __putname(to_name); 636 return err; 637 } 638 639 int hostfs_unlink(struct inode *ino, struct dentry *dentry) 640 { 641 char *file; 642 int err; 643 644 if (append) 645 return -EPERM; 646 647 if ((file = dentry_name(dentry)) == NULL) 648 return -ENOMEM; 649 650 err = unlink_file(file); 651 __putname(file); 652 return err; 653 } 654 655 int hostfs_symlink(struct inode *ino, struct dentry *dentry, const char *to) 656 { 657 char *file; 658 int err; 659 660 if ((file = dentry_name(dentry)) == NULL) 661 return -ENOMEM; 662 err = make_symlink(file, to); 663 __putname(file); 664 return err; 665 } 666 667 int hostfs_mkdir(struct inode *ino, struct dentry *dentry, int mode) 668 { 669 char *file; 670 int err; 671 672 if ((file = dentry_name(dentry)) == NULL) 673 return -ENOMEM; 674 err = do_mkdir(file, mode); 675 __putname(file); 676 return err; 677 } 678 679 int hostfs_rmdir(struct inode *ino, struct dentry *dentry) 680 { 681 char *file; 682 int err; 683 684 if ((file = dentry_name(dentry)) == NULL) 685 return -ENOMEM; 686 err = do_rmdir(file); 687 __putname(file); 688 return err; 689 } 690 691 int hostfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 692 { 693 struct inode *inode; 694 char *name; 695 int err; 696 697 inode = hostfs_iget(dir->i_sb); 698 if (IS_ERR(inode)) { 699 err = PTR_ERR(inode); 700 goto out; 701 } 702 703 err = -ENOMEM; 704 name = dentry_name(dentry); 705 if (name == NULL) 706 goto out_put; 707 708 init_special_inode(inode, mode, dev); 709 err = do_mknod(name, mode, MAJOR(dev), MINOR(dev)); 710 if (!err) 711 goto out_free; 712 713 err = read_name(inode, name); 714 __putname(name); 715 if (err) 716 goto out_put; 717 if (err) 718 goto out_put; 719 720 d_instantiate(dentry, inode); 721 return 0; 722 723 out_free: 724 __putname(name); 725 out_put: 726 iput(inode); 727 out: 728 return err; 729 } 730 731 int hostfs_rename(struct inode *from_ino, struct dentry *from, 732 struct inode *to_ino, struct dentry *to) 733 { 734 char *from_name, *to_name; 735 int err; 736 737 if ((from_name = dentry_name(from)) == NULL) 738 return -ENOMEM; 739 if ((to_name = dentry_name(to)) == NULL) { 740 __putname(from_name); 741 return -ENOMEM; 742 } 743 err = rename_file(from_name, to_name); 744 __putname(from_name); 745 __putname(to_name); 746 return err; 747 } 748 749 int hostfs_permission(struct inode *ino, int desired) 750 { 751 char *name; 752 int r = 0, w = 0, x = 0, err; 753 754 if (desired & MAY_READ) r = 1; 755 if (desired & MAY_WRITE) w = 1; 756 if (desired & MAY_EXEC) x = 1; 757 name = inode_name(ino); 758 if (name == NULL) 759 return -ENOMEM; 760 761 if (S_ISCHR(ino->i_mode) || S_ISBLK(ino->i_mode) || 762 S_ISFIFO(ino->i_mode) || S_ISSOCK(ino->i_mode)) 763 err = 0; 764 else 765 err = access_file(name, r, w, x); 766 __putname(name); 767 if (!err) 768 err = generic_permission(ino, desired, NULL); 769 return err; 770 } 771 772 int hostfs_setattr(struct dentry *dentry, struct iattr *attr) 773 { 774 struct inode *inode = dentry->d_inode; 775 struct hostfs_iattr attrs; 776 char *name; 777 int err; 778 779 int fd = HOSTFS_I(inode)->fd; 780 781 err = inode_change_ok(inode, attr); 782 if (err) 783 return err; 784 785 if (append) 786 attr->ia_valid &= ~ATTR_SIZE; 787 788 attrs.ia_valid = 0; 789 if (attr->ia_valid & ATTR_MODE) { 790 attrs.ia_valid |= HOSTFS_ATTR_MODE; 791 attrs.ia_mode = attr->ia_mode; 792 } 793 if (attr->ia_valid & ATTR_UID) { 794 attrs.ia_valid |= HOSTFS_ATTR_UID; 795 attrs.ia_uid = attr->ia_uid; 796 } 797 if (attr->ia_valid & ATTR_GID) { 798 attrs.ia_valid |= HOSTFS_ATTR_GID; 799 attrs.ia_gid = attr->ia_gid; 800 } 801 if (attr->ia_valid & ATTR_SIZE) { 802 attrs.ia_valid |= HOSTFS_ATTR_SIZE; 803 attrs.ia_size = attr->ia_size; 804 } 805 if (attr->ia_valid & ATTR_ATIME) { 806 attrs.ia_valid |= HOSTFS_ATTR_ATIME; 807 attrs.ia_atime = attr->ia_atime; 808 } 809 if (attr->ia_valid & ATTR_MTIME) { 810 attrs.ia_valid |= HOSTFS_ATTR_MTIME; 811 attrs.ia_mtime = attr->ia_mtime; 812 } 813 if (attr->ia_valid & ATTR_CTIME) { 814 attrs.ia_valid |= HOSTFS_ATTR_CTIME; 815 attrs.ia_ctime = attr->ia_ctime; 816 } 817 if (attr->ia_valid & ATTR_ATIME_SET) { 818 attrs.ia_valid |= HOSTFS_ATTR_ATIME_SET; 819 } 820 if (attr->ia_valid & ATTR_MTIME_SET) { 821 attrs.ia_valid |= HOSTFS_ATTR_MTIME_SET; 822 } 823 name = dentry_name(dentry); 824 if (name == NULL) 825 return -ENOMEM; 826 err = set_attr(name, &attrs, fd); 827 __putname(name); 828 if (err) 829 return err; 830 831 if ((attr->ia_valid & ATTR_SIZE) && 832 attr->ia_size != i_size_read(inode)) { 833 int error; 834 835 error = vmtruncate(inode, attr->ia_size); 836 if (err) 837 return err; 838 } 839 840 setattr_copy(inode, attr); 841 mark_inode_dirty(inode); 842 return 0; 843 } 844 845 static const struct inode_operations hostfs_iops = { 846 .create = hostfs_create, 847 .link = hostfs_link, 848 .unlink = hostfs_unlink, 849 .symlink = hostfs_symlink, 850 .mkdir = hostfs_mkdir, 851 .rmdir = hostfs_rmdir, 852 .mknod = hostfs_mknod, 853 .rename = hostfs_rename, 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_maxbytes = MAX_LFS_FILESIZE; 920 921 /* NULL is printed as <NULL> by sprintf: avoid that. */ 922 if (req_root == NULL) 923 req_root = ""; 924 925 err = -ENOMEM; 926 sb->s_fs_info = host_root_path = 927 kmalloc(strlen(root_ino) + strlen(req_root) + 2, GFP_KERNEL); 928 if (host_root_path == NULL) 929 goto out; 930 931 sprintf(host_root_path, "%s/%s", root_ino, req_root); 932 933 root_inode = new_inode(sb); 934 if (!root_inode) 935 goto out; 936 937 err = read_name(root_inode, host_root_path); 938 if (err) 939 goto out_put; 940 941 if (S_ISLNK(root_inode->i_mode)) { 942 char *name = follow_link(host_root_path); 943 if (IS_ERR(name)) 944 err = PTR_ERR(name); 945 else 946 err = read_name(root_inode, name); 947 kfree(name); 948 if (err) 949 goto out_put; 950 } 951 952 err = -ENOMEM; 953 sb->s_root = d_alloc_root(root_inode); 954 if (sb->s_root == NULL) 955 goto out_put; 956 957 return 0; 958 959 out_put: 960 iput(root_inode); 961 out: 962 return err; 963 } 964 965 static struct dentry *hostfs_read_sb(struct file_system_type *type, 966 int flags, const char *dev_name, 967 void *data) 968 { 969 return mount_nodev(type, flags, data, hostfs_fill_sb_common); 970 } 971 972 static void hostfs_kill_sb(struct super_block *s) 973 { 974 kill_anon_super(s); 975 kfree(s->s_fs_info); 976 } 977 978 static struct file_system_type hostfs_type = { 979 .owner = THIS_MODULE, 980 .name = "hostfs", 981 .mount = hostfs_read_sb, 982 .kill_sb = hostfs_kill_sb, 983 .fs_flags = 0, 984 }; 985 986 static int __init init_hostfs(void) 987 { 988 return register_filesystem(&hostfs_type); 989 } 990 991 static void __exit exit_hostfs(void) 992 { 993 unregister_filesystem(&hostfs_type); 994 } 995 996 module_init(init_hostfs) 997 module_exit(exit_hostfs) 998 MODULE_LICENSE("GPL"); 999