1 /* 2 * fs/libfs.c 3 * Library for filesystems writers. 4 */ 5 6 #include <linux/module.h> 7 #include <linux/pagemap.h> 8 #include <linux/slab.h> 9 #include <linux/mount.h> 10 #include <linux/vfs.h> 11 #include <linux/quotaops.h> 12 #include <linux/mutex.h> 13 #include <linux/exportfs.h> 14 #include <linux/writeback.h> 15 #include <linux/buffer_head.h> 16 17 #include <asm/uaccess.h> 18 19 static inline int simple_positive(struct dentry *dentry) 20 { 21 return dentry->d_inode && !d_unhashed(dentry); 22 } 23 24 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, 25 struct kstat *stat) 26 { 27 struct inode *inode = dentry->d_inode; 28 generic_fillattr(inode, stat); 29 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); 30 return 0; 31 } 32 33 int simple_statfs(struct dentry *dentry, struct kstatfs *buf) 34 { 35 buf->f_type = dentry->d_sb->s_magic; 36 buf->f_bsize = PAGE_CACHE_SIZE; 37 buf->f_namelen = NAME_MAX; 38 return 0; 39 } 40 41 /* 42 * Retaining negative dentries for an in-memory filesystem just wastes 43 * memory and lookup time: arrange for them to be deleted immediately. 44 */ 45 static int simple_delete_dentry(const struct dentry *dentry) 46 { 47 return 1; 48 } 49 50 /* 51 * Lookup the data. This is trivial - if the dentry didn't already 52 * exist, we know it is negative. Set d_op to delete negative dentries. 53 */ 54 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) 55 { 56 static const struct dentry_operations simple_dentry_operations = { 57 .d_delete = simple_delete_dentry, 58 }; 59 60 if (dentry->d_name.len > NAME_MAX) 61 return ERR_PTR(-ENAMETOOLONG); 62 d_set_d_op(dentry, &simple_dentry_operations); 63 d_add(dentry, NULL); 64 return NULL; 65 } 66 67 int dcache_dir_open(struct inode *inode, struct file *file) 68 { 69 static struct qstr cursor_name = {.len = 1, .name = "."}; 70 71 file->private_data = d_alloc(file->f_path.dentry, &cursor_name); 72 73 return file->private_data ? 0 : -ENOMEM; 74 } 75 76 int dcache_dir_close(struct inode *inode, struct file *file) 77 { 78 dput(file->private_data); 79 return 0; 80 } 81 82 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int origin) 83 { 84 struct dentry *dentry = file->f_path.dentry; 85 mutex_lock(&dentry->d_inode->i_mutex); 86 switch (origin) { 87 case 1: 88 offset += file->f_pos; 89 case 0: 90 if (offset >= 0) 91 break; 92 default: 93 mutex_unlock(&dentry->d_inode->i_mutex); 94 return -EINVAL; 95 } 96 if (offset != file->f_pos) { 97 file->f_pos = offset; 98 if (file->f_pos >= 2) { 99 struct list_head *p; 100 struct dentry *cursor = file->private_data; 101 loff_t n = file->f_pos - 2; 102 103 spin_lock(&dentry->d_lock); 104 /* d_lock not required for cursor */ 105 list_del(&cursor->d_u.d_child); 106 p = dentry->d_subdirs.next; 107 while (n && p != &dentry->d_subdirs) { 108 struct dentry *next; 109 next = list_entry(p, struct dentry, d_u.d_child); 110 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 111 if (simple_positive(next)) 112 n--; 113 spin_unlock(&next->d_lock); 114 p = p->next; 115 } 116 list_add_tail(&cursor->d_u.d_child, p); 117 spin_unlock(&dentry->d_lock); 118 } 119 } 120 mutex_unlock(&dentry->d_inode->i_mutex); 121 return offset; 122 } 123 124 /* Relationship between i_mode and the DT_xxx types */ 125 static inline unsigned char dt_type(struct inode *inode) 126 { 127 return (inode->i_mode >> 12) & 15; 128 } 129 130 /* 131 * Directory is locked and all positive dentries in it are safe, since 132 * for ramfs-type trees they can't go away without unlink() or rmdir(), 133 * both impossible due to the lock on directory. 134 */ 135 136 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir) 137 { 138 struct dentry *dentry = filp->f_path.dentry; 139 struct dentry *cursor = filp->private_data; 140 struct list_head *p, *q = &cursor->d_u.d_child; 141 ino_t ino; 142 int i = filp->f_pos; 143 144 switch (i) { 145 case 0: 146 ino = dentry->d_inode->i_ino; 147 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0) 148 break; 149 filp->f_pos++; 150 i++; 151 /* fallthrough */ 152 case 1: 153 ino = parent_ino(dentry); 154 if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0) 155 break; 156 filp->f_pos++; 157 i++; 158 /* fallthrough */ 159 default: 160 spin_lock(&dentry->d_lock); 161 if (filp->f_pos == 2) 162 list_move(q, &dentry->d_subdirs); 163 164 for (p=q->next; p != &dentry->d_subdirs; p=p->next) { 165 struct dentry *next; 166 next = list_entry(p, struct dentry, d_u.d_child); 167 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 168 if (!simple_positive(next)) { 169 spin_unlock(&next->d_lock); 170 continue; 171 } 172 173 spin_unlock(&next->d_lock); 174 spin_unlock(&dentry->d_lock); 175 if (filldir(dirent, next->d_name.name, 176 next->d_name.len, filp->f_pos, 177 next->d_inode->i_ino, 178 dt_type(next->d_inode)) < 0) 179 return 0; 180 spin_lock(&dentry->d_lock); 181 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 182 /* next is still alive */ 183 list_move(q, p); 184 spin_unlock(&next->d_lock); 185 p = q; 186 filp->f_pos++; 187 } 188 spin_unlock(&dentry->d_lock); 189 } 190 return 0; 191 } 192 193 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) 194 { 195 return -EISDIR; 196 } 197 198 const struct file_operations simple_dir_operations = { 199 .open = dcache_dir_open, 200 .release = dcache_dir_close, 201 .llseek = dcache_dir_lseek, 202 .read = generic_read_dir, 203 .readdir = dcache_readdir, 204 .fsync = noop_fsync, 205 }; 206 207 const struct inode_operations simple_dir_inode_operations = { 208 .lookup = simple_lookup, 209 }; 210 211 static const struct super_operations simple_super_operations = { 212 .statfs = simple_statfs, 213 }; 214 215 /* 216 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that 217 * will never be mountable) 218 */ 219 struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, 220 const struct super_operations *ops, 221 const struct dentry_operations *dops, unsigned long magic) 222 { 223 struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL); 224 struct dentry *dentry; 225 struct inode *root; 226 struct qstr d_name = {.name = name, .len = strlen(name)}; 227 228 if (IS_ERR(s)) 229 return ERR_CAST(s); 230 231 s->s_flags = MS_NOUSER; 232 s->s_maxbytes = MAX_LFS_FILESIZE; 233 s->s_blocksize = PAGE_SIZE; 234 s->s_blocksize_bits = PAGE_SHIFT; 235 s->s_magic = magic; 236 s->s_op = ops ? ops : &simple_super_operations; 237 s->s_time_gran = 1; 238 root = new_inode(s); 239 if (!root) 240 goto Enomem; 241 /* 242 * since this is the first inode, make it number 1. New inodes created 243 * after this must take care not to collide with it (by passing 244 * max_reserved of 1 to iunique). 245 */ 246 root->i_ino = 1; 247 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; 248 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; 249 dentry = d_alloc(NULL, &d_name); 250 if (!dentry) { 251 iput(root); 252 goto Enomem; 253 } 254 dentry->d_sb = s; 255 dentry->d_parent = dentry; 256 d_instantiate(dentry, root); 257 s->s_root = dentry; 258 s->s_d_op = dops; 259 s->s_flags |= MS_ACTIVE; 260 return dget(s->s_root); 261 262 Enomem: 263 deactivate_locked_super(s); 264 return ERR_PTR(-ENOMEM); 265 } 266 267 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 268 { 269 struct inode *inode = old_dentry->d_inode; 270 271 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 272 inc_nlink(inode); 273 ihold(inode); 274 dget(dentry); 275 d_instantiate(dentry, inode); 276 return 0; 277 } 278 279 int simple_empty(struct dentry *dentry) 280 { 281 struct dentry *child; 282 int ret = 0; 283 284 spin_lock(&dentry->d_lock); 285 list_for_each_entry(child, &dentry->d_subdirs, d_u.d_child) { 286 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); 287 if (simple_positive(child)) { 288 spin_unlock(&child->d_lock); 289 goto out; 290 } 291 spin_unlock(&child->d_lock); 292 } 293 ret = 1; 294 out: 295 spin_unlock(&dentry->d_lock); 296 return ret; 297 } 298 299 int simple_unlink(struct inode *dir, struct dentry *dentry) 300 { 301 struct inode *inode = dentry->d_inode; 302 303 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 304 drop_nlink(inode); 305 dput(dentry); 306 return 0; 307 } 308 309 int simple_rmdir(struct inode *dir, struct dentry *dentry) 310 { 311 if (!simple_empty(dentry)) 312 return -ENOTEMPTY; 313 314 drop_nlink(dentry->d_inode); 315 simple_unlink(dir, dentry); 316 drop_nlink(dir); 317 return 0; 318 } 319 320 int simple_rename(struct inode *old_dir, struct dentry *old_dentry, 321 struct inode *new_dir, struct dentry *new_dentry) 322 { 323 struct inode *inode = old_dentry->d_inode; 324 int they_are_dirs = S_ISDIR(old_dentry->d_inode->i_mode); 325 326 if (!simple_empty(new_dentry)) 327 return -ENOTEMPTY; 328 329 if (new_dentry->d_inode) { 330 simple_unlink(new_dir, new_dentry); 331 if (they_are_dirs) 332 drop_nlink(old_dir); 333 } else if (they_are_dirs) { 334 drop_nlink(old_dir); 335 inc_nlink(new_dir); 336 } 337 338 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = 339 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; 340 341 return 0; 342 } 343 344 /** 345 * simple_setattr - setattr for simple filesystem 346 * @dentry: dentry 347 * @iattr: iattr structure 348 * 349 * Returns 0 on success, -error on failure. 350 * 351 * simple_setattr is a simple ->setattr implementation without a proper 352 * implementation of size changes. 353 * 354 * It can either be used for in-memory filesystems or special files 355 * on simple regular filesystems. Anything that needs to change on-disk 356 * or wire state on size changes needs its own setattr method. 357 */ 358 int simple_setattr(struct dentry *dentry, struct iattr *iattr) 359 { 360 struct inode *inode = dentry->d_inode; 361 int error; 362 363 WARN_ON_ONCE(inode->i_op->truncate); 364 365 error = inode_change_ok(inode, iattr); 366 if (error) 367 return error; 368 369 if (iattr->ia_valid & ATTR_SIZE) 370 truncate_setsize(inode, iattr->ia_size); 371 setattr_copy(inode, iattr); 372 mark_inode_dirty(inode); 373 return 0; 374 } 375 EXPORT_SYMBOL(simple_setattr); 376 377 int simple_readpage(struct file *file, struct page *page) 378 { 379 clear_highpage(page); 380 flush_dcache_page(page); 381 SetPageUptodate(page); 382 unlock_page(page); 383 return 0; 384 } 385 386 int simple_write_begin(struct file *file, struct address_space *mapping, 387 loff_t pos, unsigned len, unsigned flags, 388 struct page **pagep, void **fsdata) 389 { 390 struct page *page; 391 pgoff_t index; 392 393 index = pos >> PAGE_CACHE_SHIFT; 394 395 page = grab_cache_page_write_begin(mapping, index, flags); 396 if (!page) 397 return -ENOMEM; 398 399 *pagep = page; 400 401 if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { 402 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 403 404 zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); 405 } 406 return 0; 407 } 408 409 /** 410 * simple_write_end - .write_end helper for non-block-device FSes 411 * @available: See .write_end of address_space_operations 412 * @file: " 413 * @mapping: " 414 * @pos: " 415 * @len: " 416 * @copied: " 417 * @page: " 418 * @fsdata: " 419 * 420 * simple_write_end does the minimum needed for updating a page after writing is 421 * done. It has the same API signature as the .write_end of 422 * address_space_operations vector. So it can just be set onto .write_end for 423 * FSes that don't need any other processing. i_mutex is assumed to be held. 424 * Block based filesystems should use generic_write_end(). 425 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty 426 * is not called, so a filesystem that actually does store data in .write_inode 427 * should extend on what's done here with a call to mark_inode_dirty() in the 428 * case that i_size has changed. 429 */ 430 int simple_write_end(struct file *file, struct address_space *mapping, 431 loff_t pos, unsigned len, unsigned copied, 432 struct page *page, void *fsdata) 433 { 434 struct inode *inode = page->mapping->host; 435 loff_t last_pos = pos + copied; 436 437 /* zero the stale part of the page if we did a short copy */ 438 if (copied < len) { 439 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 440 441 zero_user(page, from + copied, len - copied); 442 } 443 444 if (!PageUptodate(page)) 445 SetPageUptodate(page); 446 /* 447 * No need to use i_size_read() here, the i_size 448 * cannot change under us because we hold the i_mutex. 449 */ 450 if (last_pos > inode->i_size) 451 i_size_write(inode, last_pos); 452 453 set_page_dirty(page); 454 unlock_page(page); 455 page_cache_release(page); 456 457 return copied; 458 } 459 460 /* 461 * the inodes created here are not hashed. If you use iunique to generate 462 * unique inode values later for this filesystem, then you must take care 463 * to pass it an appropriate max_reserved value to avoid collisions. 464 */ 465 int simple_fill_super(struct super_block *s, unsigned long magic, 466 struct tree_descr *files) 467 { 468 struct inode *inode; 469 struct dentry *root; 470 struct dentry *dentry; 471 int i; 472 473 s->s_blocksize = PAGE_CACHE_SIZE; 474 s->s_blocksize_bits = PAGE_CACHE_SHIFT; 475 s->s_magic = magic; 476 s->s_op = &simple_super_operations; 477 s->s_time_gran = 1; 478 479 inode = new_inode(s); 480 if (!inode) 481 return -ENOMEM; 482 /* 483 * because the root inode is 1, the files array must not contain an 484 * entry at index 1 485 */ 486 inode->i_ino = 1; 487 inode->i_mode = S_IFDIR | 0755; 488 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 489 inode->i_op = &simple_dir_inode_operations; 490 inode->i_fop = &simple_dir_operations; 491 inode->i_nlink = 2; 492 root = d_alloc_root(inode); 493 if (!root) { 494 iput(inode); 495 return -ENOMEM; 496 } 497 for (i = 0; !files->name || files->name[0]; i++, files++) { 498 if (!files->name) 499 continue; 500 501 /* warn if it tries to conflict with the root inode */ 502 if (unlikely(i == 1)) 503 printk(KERN_WARNING "%s: %s passed in a files array" 504 "with an index of 1!\n", __func__, 505 s->s_type->name); 506 507 dentry = d_alloc_name(root, files->name); 508 if (!dentry) 509 goto out; 510 inode = new_inode(s); 511 if (!inode) 512 goto out; 513 inode->i_mode = S_IFREG | files->mode; 514 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 515 inode->i_fop = files->ops; 516 inode->i_ino = i; 517 d_add(dentry, inode); 518 } 519 s->s_root = root; 520 return 0; 521 out: 522 d_genocide(root); 523 dput(root); 524 return -ENOMEM; 525 } 526 527 static DEFINE_SPINLOCK(pin_fs_lock); 528 529 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) 530 { 531 struct vfsmount *mnt = NULL; 532 spin_lock(&pin_fs_lock); 533 if (unlikely(!*mount)) { 534 spin_unlock(&pin_fs_lock); 535 mnt = vfs_kern_mount(type, 0, type->name, NULL); 536 if (IS_ERR(mnt)) 537 return PTR_ERR(mnt); 538 spin_lock(&pin_fs_lock); 539 if (!*mount) 540 *mount = mnt; 541 } 542 mntget(*mount); 543 ++*count; 544 spin_unlock(&pin_fs_lock); 545 mntput(mnt); 546 return 0; 547 } 548 549 void simple_release_fs(struct vfsmount **mount, int *count) 550 { 551 struct vfsmount *mnt; 552 spin_lock(&pin_fs_lock); 553 mnt = *mount; 554 if (!--*count) 555 *mount = NULL; 556 spin_unlock(&pin_fs_lock); 557 mntput(mnt); 558 } 559 560 /** 561 * simple_read_from_buffer - copy data from the buffer to user space 562 * @to: the user space buffer to read to 563 * @count: the maximum number of bytes to read 564 * @ppos: the current position in the buffer 565 * @from: the buffer to read from 566 * @available: the size of the buffer 567 * 568 * The simple_read_from_buffer() function reads up to @count bytes from the 569 * buffer @from at offset @ppos into the user space address starting at @to. 570 * 571 * On success, the number of bytes read is returned and the offset @ppos is 572 * advanced by this number, or negative value is returned on error. 573 **/ 574 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, 575 const void *from, size_t available) 576 { 577 loff_t pos = *ppos; 578 size_t ret; 579 580 if (pos < 0) 581 return -EINVAL; 582 if (pos >= available || !count) 583 return 0; 584 if (count > available - pos) 585 count = available - pos; 586 ret = copy_to_user(to, from + pos, count); 587 if (ret == count) 588 return -EFAULT; 589 count -= ret; 590 *ppos = pos + count; 591 return count; 592 } 593 594 /** 595 * simple_write_to_buffer - copy data from user space to the buffer 596 * @to: the buffer to write to 597 * @available: the size of the buffer 598 * @ppos: the current position in the buffer 599 * @from: the user space buffer to read from 600 * @count: the maximum number of bytes to read 601 * 602 * The simple_write_to_buffer() function reads up to @count bytes from the user 603 * space address starting at @from into the buffer @to at offset @ppos. 604 * 605 * On success, the number of bytes written is returned and the offset @ppos is 606 * advanced by this number, or negative value is returned on error. 607 **/ 608 ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, 609 const void __user *from, size_t count) 610 { 611 loff_t pos = *ppos; 612 size_t res; 613 614 if (pos < 0) 615 return -EINVAL; 616 if (pos >= available || !count) 617 return 0; 618 if (count > available - pos) 619 count = available - pos; 620 res = copy_from_user(to + pos, from, count); 621 if (res == count) 622 return -EFAULT; 623 count -= res; 624 *ppos = pos + count; 625 return count; 626 } 627 628 /** 629 * memory_read_from_buffer - copy data from the buffer 630 * @to: the kernel space buffer to read to 631 * @count: the maximum number of bytes to read 632 * @ppos: the current position in the buffer 633 * @from: the buffer to read from 634 * @available: the size of the buffer 635 * 636 * The memory_read_from_buffer() function reads up to @count bytes from the 637 * buffer @from at offset @ppos into the kernel space address starting at @to. 638 * 639 * On success, the number of bytes read is returned and the offset @ppos is 640 * advanced by this number, or negative value is returned on error. 641 **/ 642 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, 643 const void *from, size_t available) 644 { 645 loff_t pos = *ppos; 646 647 if (pos < 0) 648 return -EINVAL; 649 if (pos >= available) 650 return 0; 651 if (count > available - pos) 652 count = available - pos; 653 memcpy(to, from + pos, count); 654 *ppos = pos + count; 655 656 return count; 657 } 658 659 /* 660 * Transaction based IO. 661 * The file expects a single write which triggers the transaction, and then 662 * possibly a read which collects the result - which is stored in a 663 * file-local buffer. 664 */ 665 666 void simple_transaction_set(struct file *file, size_t n) 667 { 668 struct simple_transaction_argresp *ar = file->private_data; 669 670 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); 671 672 /* 673 * The barrier ensures that ar->size will really remain zero until 674 * ar->data is ready for reading. 675 */ 676 smp_mb(); 677 ar->size = n; 678 } 679 680 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) 681 { 682 struct simple_transaction_argresp *ar; 683 static DEFINE_SPINLOCK(simple_transaction_lock); 684 685 if (size > SIMPLE_TRANSACTION_LIMIT - 1) 686 return ERR_PTR(-EFBIG); 687 688 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); 689 if (!ar) 690 return ERR_PTR(-ENOMEM); 691 692 spin_lock(&simple_transaction_lock); 693 694 /* only one write allowed per open */ 695 if (file->private_data) { 696 spin_unlock(&simple_transaction_lock); 697 free_page((unsigned long)ar); 698 return ERR_PTR(-EBUSY); 699 } 700 701 file->private_data = ar; 702 703 spin_unlock(&simple_transaction_lock); 704 705 if (copy_from_user(ar->data, buf, size)) 706 return ERR_PTR(-EFAULT); 707 708 return ar->data; 709 } 710 711 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) 712 { 713 struct simple_transaction_argresp *ar = file->private_data; 714 715 if (!ar) 716 return 0; 717 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); 718 } 719 720 int simple_transaction_release(struct inode *inode, struct file *file) 721 { 722 free_page((unsigned long)file->private_data); 723 return 0; 724 } 725 726 /* Simple attribute files */ 727 728 struct simple_attr { 729 int (*get)(void *, u64 *); 730 int (*set)(void *, u64); 731 char get_buf[24]; /* enough to store a u64 and "\n\0" */ 732 char set_buf[24]; 733 void *data; 734 const char *fmt; /* format for read operation */ 735 struct mutex mutex; /* protects access to these buffers */ 736 }; 737 738 /* simple_attr_open is called by an actual attribute open file operation 739 * to set the attribute specific access operations. */ 740 int simple_attr_open(struct inode *inode, struct file *file, 741 int (*get)(void *, u64 *), int (*set)(void *, u64), 742 const char *fmt) 743 { 744 struct simple_attr *attr; 745 746 attr = kmalloc(sizeof(*attr), GFP_KERNEL); 747 if (!attr) 748 return -ENOMEM; 749 750 attr->get = get; 751 attr->set = set; 752 attr->data = inode->i_private; 753 attr->fmt = fmt; 754 mutex_init(&attr->mutex); 755 756 file->private_data = attr; 757 758 return nonseekable_open(inode, file); 759 } 760 761 int simple_attr_release(struct inode *inode, struct file *file) 762 { 763 kfree(file->private_data); 764 return 0; 765 } 766 767 /* read from the buffer that is filled with the get function */ 768 ssize_t simple_attr_read(struct file *file, char __user *buf, 769 size_t len, loff_t *ppos) 770 { 771 struct simple_attr *attr; 772 size_t size; 773 ssize_t ret; 774 775 attr = file->private_data; 776 777 if (!attr->get) 778 return -EACCES; 779 780 ret = mutex_lock_interruptible(&attr->mutex); 781 if (ret) 782 return ret; 783 784 if (*ppos) { /* continued read */ 785 size = strlen(attr->get_buf); 786 } else { /* first read */ 787 u64 val; 788 ret = attr->get(attr->data, &val); 789 if (ret) 790 goto out; 791 792 size = scnprintf(attr->get_buf, sizeof(attr->get_buf), 793 attr->fmt, (unsigned long long)val); 794 } 795 796 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); 797 out: 798 mutex_unlock(&attr->mutex); 799 return ret; 800 } 801 802 /* interpret the buffer as a number to call the set function with */ 803 ssize_t simple_attr_write(struct file *file, const char __user *buf, 804 size_t len, loff_t *ppos) 805 { 806 struct simple_attr *attr; 807 u64 val; 808 size_t size; 809 ssize_t ret; 810 811 attr = file->private_data; 812 if (!attr->set) 813 return -EACCES; 814 815 ret = mutex_lock_interruptible(&attr->mutex); 816 if (ret) 817 return ret; 818 819 ret = -EFAULT; 820 size = min(sizeof(attr->set_buf) - 1, len); 821 if (copy_from_user(attr->set_buf, buf, size)) 822 goto out; 823 824 attr->set_buf[size] = '\0'; 825 val = simple_strtol(attr->set_buf, NULL, 0); 826 ret = attr->set(attr->data, val); 827 if (ret == 0) 828 ret = len; /* on success, claim we got the whole input */ 829 out: 830 mutex_unlock(&attr->mutex); 831 return ret; 832 } 833 834 /** 835 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation 836 * @sb: filesystem to do the file handle conversion on 837 * @fid: file handle to convert 838 * @fh_len: length of the file handle in bytes 839 * @fh_type: type of file handle 840 * @get_inode: filesystem callback to retrieve inode 841 * 842 * This function decodes @fid as long as it has one of the well-known 843 * Linux filehandle types and calls @get_inode on it to retrieve the 844 * inode for the object specified in the file handle. 845 */ 846 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, 847 int fh_len, int fh_type, struct inode *(*get_inode) 848 (struct super_block *sb, u64 ino, u32 gen)) 849 { 850 struct inode *inode = NULL; 851 852 if (fh_len < 2) 853 return NULL; 854 855 switch (fh_type) { 856 case FILEID_INO32_GEN: 857 case FILEID_INO32_GEN_PARENT: 858 inode = get_inode(sb, fid->i32.ino, fid->i32.gen); 859 break; 860 } 861 862 return d_obtain_alias(inode); 863 } 864 EXPORT_SYMBOL_GPL(generic_fh_to_dentry); 865 866 /** 867 * generic_fh_to_dentry - generic helper for the fh_to_parent export operation 868 * @sb: filesystem to do the file handle conversion on 869 * @fid: file handle to convert 870 * @fh_len: length of the file handle in bytes 871 * @fh_type: type of file handle 872 * @get_inode: filesystem callback to retrieve inode 873 * 874 * This function decodes @fid as long as it has one of the well-known 875 * Linux filehandle types and calls @get_inode on it to retrieve the 876 * inode for the _parent_ object specified in the file handle if it 877 * is specified in the file handle, or NULL otherwise. 878 */ 879 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, 880 int fh_len, int fh_type, struct inode *(*get_inode) 881 (struct super_block *sb, u64 ino, u32 gen)) 882 { 883 struct inode *inode = NULL; 884 885 if (fh_len <= 2) 886 return NULL; 887 888 switch (fh_type) { 889 case FILEID_INO32_GEN_PARENT: 890 inode = get_inode(sb, fid->i32.parent_ino, 891 (fh_len > 3 ? fid->i32.parent_gen : 0)); 892 break; 893 } 894 895 return d_obtain_alias(inode); 896 } 897 EXPORT_SYMBOL_GPL(generic_fh_to_parent); 898 899 /** 900 * generic_file_fsync - generic fsync implementation for simple filesystems 901 * @file: file to synchronize 902 * @datasync: only synchronize essential metadata if true 903 * 904 * This is a generic implementation of the fsync method for simple 905 * filesystems which track all non-inode metadata in the buffers list 906 * hanging off the address_space structure. 907 */ 908 int generic_file_fsync(struct file *file, int datasync) 909 { 910 struct inode *inode = file->f_mapping->host; 911 int err; 912 int ret; 913 914 ret = sync_mapping_buffers(inode->i_mapping); 915 if (!(inode->i_state & I_DIRTY)) 916 return ret; 917 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 918 return ret; 919 920 err = sync_inode_metadata(inode, 1); 921 if (ret == 0) 922 ret = err; 923 return ret; 924 } 925 EXPORT_SYMBOL(generic_file_fsync); 926 927 /** 928 * generic_check_addressable - Check addressability of file system 929 * @blocksize_bits: log of file system block size 930 * @num_blocks: number of blocks in file system 931 * 932 * Determine whether a file system with @num_blocks blocks (and a 933 * block size of 2**@blocksize_bits) is addressable by the sector_t 934 * and page cache of the system. Return 0 if so and -EFBIG otherwise. 935 */ 936 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) 937 { 938 u64 last_fs_block = num_blocks - 1; 939 u64 last_fs_page = 940 last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); 941 942 if (unlikely(num_blocks == 0)) 943 return 0; 944 945 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) 946 return -EINVAL; 947 948 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || 949 (last_fs_page > (pgoff_t)(~0ULL))) { 950 return -EFBIG; 951 } 952 return 0; 953 } 954 EXPORT_SYMBOL(generic_check_addressable); 955 956 /* 957 * No-op implementation of ->fsync for in-memory filesystems. 958 */ 959 int noop_fsync(struct file *file, int datasync) 960 { 961 return 0; 962 } 963 964 EXPORT_SYMBOL(dcache_dir_close); 965 EXPORT_SYMBOL(dcache_dir_lseek); 966 EXPORT_SYMBOL(dcache_dir_open); 967 EXPORT_SYMBOL(dcache_readdir); 968 EXPORT_SYMBOL(generic_read_dir); 969 EXPORT_SYMBOL(mount_pseudo); 970 EXPORT_SYMBOL(simple_write_begin); 971 EXPORT_SYMBOL(simple_write_end); 972 EXPORT_SYMBOL(simple_dir_inode_operations); 973 EXPORT_SYMBOL(simple_dir_operations); 974 EXPORT_SYMBOL(simple_empty); 975 EXPORT_SYMBOL(simple_fill_super); 976 EXPORT_SYMBOL(simple_getattr); 977 EXPORT_SYMBOL(simple_link); 978 EXPORT_SYMBOL(simple_lookup); 979 EXPORT_SYMBOL(simple_pin_fs); 980 EXPORT_SYMBOL(simple_readpage); 981 EXPORT_SYMBOL(simple_release_fs); 982 EXPORT_SYMBOL(simple_rename); 983 EXPORT_SYMBOL(simple_rmdir); 984 EXPORT_SYMBOL(simple_statfs); 985 EXPORT_SYMBOL(noop_fsync); 986 EXPORT_SYMBOL(simple_unlink); 987 EXPORT_SYMBOL(simple_read_from_buffer); 988 EXPORT_SYMBOL(simple_write_to_buffer); 989 EXPORT_SYMBOL(memory_read_from_buffer); 990 EXPORT_SYMBOL(simple_transaction_set); 991 EXPORT_SYMBOL(simple_transaction_get); 992 EXPORT_SYMBOL(simple_transaction_read); 993 EXPORT_SYMBOL(simple_transaction_release); 994 EXPORT_SYMBOL_GPL(simple_attr_open); 995 EXPORT_SYMBOL_GPL(simple_attr_release); 996 EXPORT_SYMBOL_GPL(simple_attr_read); 997 EXPORT_SYMBOL_GPL(simple_attr_write); 998