1 /* 2 * fs/libfs.c 3 * Library for filesystems writers. 4 */ 5 6 #include <linux/blkdev.h> 7 #include <linux/export.h> 8 #include <linux/pagemap.h> 9 #include <linux/slab.h> 10 #include <linux/mount.h> 11 #include <linux/vfs.h> 12 #include <linux/quotaops.h> 13 #include <linux/mutex.h> 14 #include <linux/namei.h> 15 #include <linux/exportfs.h> 16 #include <linux/writeback.h> 17 #include <linux/buffer_head.h> /* sync_mapping_buffers */ 18 19 #include <asm/uaccess.h> 20 21 #include "internal.h" 22 23 static inline int simple_positive(struct dentry *dentry) 24 { 25 return dentry->d_inode && !d_unhashed(dentry); 26 } 27 28 int simple_getattr(struct vfsmount *mnt, struct dentry *dentry, 29 struct kstat *stat) 30 { 31 struct inode *inode = dentry->d_inode; 32 generic_fillattr(inode, stat); 33 stat->blocks = inode->i_mapping->nrpages << (PAGE_CACHE_SHIFT - 9); 34 return 0; 35 } 36 EXPORT_SYMBOL(simple_getattr); 37 38 int simple_statfs(struct dentry *dentry, struct kstatfs *buf) 39 { 40 buf->f_type = dentry->d_sb->s_magic; 41 buf->f_bsize = PAGE_CACHE_SIZE; 42 buf->f_namelen = NAME_MAX; 43 return 0; 44 } 45 EXPORT_SYMBOL(simple_statfs); 46 47 /* 48 * Retaining negative dentries for an in-memory filesystem just wastes 49 * memory and lookup time: arrange for them to be deleted immediately. 50 */ 51 int always_delete_dentry(const struct dentry *dentry) 52 { 53 return 1; 54 } 55 EXPORT_SYMBOL(always_delete_dentry); 56 57 const struct dentry_operations simple_dentry_operations = { 58 .d_delete = always_delete_dentry, 59 }; 60 EXPORT_SYMBOL(simple_dentry_operations); 61 62 /* 63 * Lookup the data. This is trivial - if the dentry didn't already 64 * exist, we know it is negative. Set d_op to delete negative dentries. 65 */ 66 struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 67 { 68 if (dentry->d_name.len > NAME_MAX) 69 return ERR_PTR(-ENAMETOOLONG); 70 if (!dentry->d_sb->s_d_op) 71 d_set_d_op(dentry, &simple_dentry_operations); 72 d_add(dentry, NULL); 73 return NULL; 74 } 75 EXPORT_SYMBOL(simple_lookup); 76 77 int dcache_dir_open(struct inode *inode, struct file *file) 78 { 79 static struct qstr cursor_name = QSTR_INIT(".", 1); 80 81 file->private_data = d_alloc(file->f_path.dentry, &cursor_name); 82 83 return file->private_data ? 0 : -ENOMEM; 84 } 85 EXPORT_SYMBOL(dcache_dir_open); 86 87 int dcache_dir_close(struct inode *inode, struct file *file) 88 { 89 dput(file->private_data); 90 return 0; 91 } 92 EXPORT_SYMBOL(dcache_dir_close); 93 94 loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) 95 { 96 struct dentry *dentry = file->f_path.dentry; 97 mutex_lock(&dentry->d_inode->i_mutex); 98 switch (whence) { 99 case 1: 100 offset += file->f_pos; 101 case 0: 102 if (offset >= 0) 103 break; 104 default: 105 mutex_unlock(&dentry->d_inode->i_mutex); 106 return -EINVAL; 107 } 108 if (offset != file->f_pos) { 109 file->f_pos = offset; 110 if (file->f_pos >= 2) { 111 struct list_head *p; 112 struct dentry *cursor = file->private_data; 113 loff_t n = file->f_pos - 2; 114 115 spin_lock(&dentry->d_lock); 116 /* d_lock not required for cursor */ 117 list_del(&cursor->d_child); 118 p = dentry->d_subdirs.next; 119 while (n && p != &dentry->d_subdirs) { 120 struct dentry *next; 121 next = list_entry(p, struct dentry, d_child); 122 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 123 if (simple_positive(next)) 124 n--; 125 spin_unlock(&next->d_lock); 126 p = p->next; 127 } 128 list_add_tail(&cursor->d_child, p); 129 spin_unlock(&dentry->d_lock); 130 } 131 } 132 mutex_unlock(&dentry->d_inode->i_mutex); 133 return offset; 134 } 135 EXPORT_SYMBOL(dcache_dir_lseek); 136 137 /* Relationship between i_mode and the DT_xxx types */ 138 static inline unsigned char dt_type(struct inode *inode) 139 { 140 return (inode->i_mode >> 12) & 15; 141 } 142 143 /* 144 * Directory is locked and all positive dentries in it are safe, since 145 * for ramfs-type trees they can't go away without unlink() or rmdir(), 146 * both impossible due to the lock on directory. 147 */ 148 149 int dcache_readdir(struct file *file, struct dir_context *ctx) 150 { 151 struct dentry *dentry = file->f_path.dentry; 152 struct dentry *cursor = file->private_data; 153 struct list_head *p, *q = &cursor->d_child; 154 155 if (!dir_emit_dots(file, ctx)) 156 return 0; 157 spin_lock(&dentry->d_lock); 158 if (ctx->pos == 2) 159 list_move(q, &dentry->d_subdirs); 160 161 for (p = q->next; p != &dentry->d_subdirs; p = p->next) { 162 struct dentry *next = list_entry(p, struct dentry, d_child); 163 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 164 if (!simple_positive(next)) { 165 spin_unlock(&next->d_lock); 166 continue; 167 } 168 169 spin_unlock(&next->d_lock); 170 spin_unlock(&dentry->d_lock); 171 if (!dir_emit(ctx, next->d_name.name, next->d_name.len, 172 next->d_inode->i_ino, dt_type(next->d_inode))) 173 return 0; 174 spin_lock(&dentry->d_lock); 175 spin_lock_nested(&next->d_lock, DENTRY_D_LOCK_NESTED); 176 /* next is still alive */ 177 list_move(q, p); 178 spin_unlock(&next->d_lock); 179 p = q; 180 ctx->pos++; 181 } 182 spin_unlock(&dentry->d_lock); 183 return 0; 184 } 185 EXPORT_SYMBOL(dcache_readdir); 186 187 ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) 188 { 189 return -EISDIR; 190 } 191 EXPORT_SYMBOL(generic_read_dir); 192 193 const struct file_operations simple_dir_operations = { 194 .open = dcache_dir_open, 195 .release = dcache_dir_close, 196 .llseek = dcache_dir_lseek, 197 .read = generic_read_dir, 198 .iterate = dcache_readdir, 199 .fsync = noop_fsync, 200 }; 201 EXPORT_SYMBOL(simple_dir_operations); 202 203 const struct inode_operations simple_dir_inode_operations = { 204 .lookup = simple_lookup, 205 }; 206 EXPORT_SYMBOL(simple_dir_inode_operations); 207 208 static const struct super_operations simple_super_operations = { 209 .statfs = simple_statfs, 210 }; 211 212 /* 213 * Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that 214 * will never be mountable) 215 */ 216 struct dentry *mount_pseudo(struct file_system_type *fs_type, char *name, 217 const struct super_operations *ops, 218 const struct dentry_operations *dops, unsigned long magic) 219 { 220 struct super_block *s; 221 struct dentry *dentry; 222 struct inode *root; 223 struct qstr d_name = QSTR_INIT(name, strlen(name)); 224 225 s = sget(fs_type, NULL, set_anon_super, MS_NOUSER, NULL); 226 if (IS_ERR(s)) 227 return ERR_CAST(s); 228 229 s->s_maxbytes = MAX_LFS_FILESIZE; 230 s->s_blocksize = PAGE_SIZE; 231 s->s_blocksize_bits = PAGE_SHIFT; 232 s->s_magic = magic; 233 s->s_op = ops ? ops : &simple_super_operations; 234 s->s_time_gran = 1; 235 root = new_inode(s); 236 if (!root) 237 goto Enomem; 238 /* 239 * since this is the first inode, make it number 1. New inodes created 240 * after this must take care not to collide with it (by passing 241 * max_reserved of 1 to iunique). 242 */ 243 root->i_ino = 1; 244 root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; 245 root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME; 246 dentry = __d_alloc(s, &d_name); 247 if (!dentry) { 248 iput(root); 249 goto Enomem; 250 } 251 d_instantiate(dentry, root); 252 s->s_root = dentry; 253 s->s_d_op = dops; 254 s->s_flags |= MS_ACTIVE; 255 return dget(s->s_root); 256 257 Enomem: 258 deactivate_locked_super(s); 259 return ERR_PTR(-ENOMEM); 260 } 261 EXPORT_SYMBOL(mount_pseudo); 262 263 int simple_open(struct inode *inode, struct file *file) 264 { 265 if (inode->i_private) 266 file->private_data = inode->i_private; 267 return 0; 268 } 269 EXPORT_SYMBOL(simple_open); 270 271 int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 272 { 273 struct inode *inode = old_dentry->d_inode; 274 275 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 276 inc_nlink(inode); 277 ihold(inode); 278 dget(dentry); 279 d_instantiate(dentry, inode); 280 return 0; 281 } 282 EXPORT_SYMBOL(simple_link); 283 284 int simple_empty(struct dentry *dentry) 285 { 286 struct dentry *child; 287 int ret = 0; 288 289 spin_lock(&dentry->d_lock); 290 list_for_each_entry(child, &dentry->d_subdirs, d_child) { 291 spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); 292 if (simple_positive(child)) { 293 spin_unlock(&child->d_lock); 294 goto out; 295 } 296 spin_unlock(&child->d_lock); 297 } 298 ret = 1; 299 out: 300 spin_unlock(&dentry->d_lock); 301 return ret; 302 } 303 EXPORT_SYMBOL(simple_empty); 304 305 int simple_unlink(struct inode *dir, struct dentry *dentry) 306 { 307 struct inode *inode = dentry->d_inode; 308 309 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 310 drop_nlink(inode); 311 dput(dentry); 312 return 0; 313 } 314 EXPORT_SYMBOL(simple_unlink); 315 316 int simple_rmdir(struct inode *dir, struct dentry *dentry) 317 { 318 if (!simple_empty(dentry)) 319 return -ENOTEMPTY; 320 321 drop_nlink(dentry->d_inode); 322 simple_unlink(dir, dentry); 323 drop_nlink(dir); 324 return 0; 325 } 326 EXPORT_SYMBOL(simple_rmdir); 327 328 int simple_rename(struct inode *old_dir, struct dentry *old_dentry, 329 struct inode *new_dir, struct dentry *new_dentry) 330 { 331 struct inode *inode = old_dentry->d_inode; 332 int they_are_dirs = d_is_dir(old_dentry); 333 334 if (!simple_empty(new_dentry)) 335 return -ENOTEMPTY; 336 337 if (new_dentry->d_inode) { 338 simple_unlink(new_dir, new_dentry); 339 if (they_are_dirs) { 340 drop_nlink(new_dentry->d_inode); 341 drop_nlink(old_dir); 342 } 343 } else if (they_are_dirs) { 344 drop_nlink(old_dir); 345 inc_nlink(new_dir); 346 } 347 348 old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = 349 new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; 350 351 return 0; 352 } 353 EXPORT_SYMBOL(simple_rename); 354 355 /** 356 * simple_setattr - setattr for simple filesystem 357 * @dentry: dentry 358 * @iattr: iattr structure 359 * 360 * Returns 0 on success, -error on failure. 361 * 362 * simple_setattr is a simple ->setattr implementation without a proper 363 * implementation of size changes. 364 * 365 * It can either be used for in-memory filesystems or special files 366 * on simple regular filesystems. Anything that needs to change on-disk 367 * or wire state on size changes needs its own setattr method. 368 */ 369 int simple_setattr(struct dentry *dentry, struct iattr *iattr) 370 { 371 struct inode *inode = dentry->d_inode; 372 int error; 373 374 error = inode_change_ok(inode, iattr); 375 if (error) 376 return error; 377 378 if (iattr->ia_valid & ATTR_SIZE) 379 truncate_setsize(inode, iattr->ia_size); 380 setattr_copy(inode, iattr); 381 mark_inode_dirty(inode); 382 return 0; 383 } 384 EXPORT_SYMBOL(simple_setattr); 385 386 int simple_readpage(struct file *file, struct page *page) 387 { 388 clear_highpage(page); 389 flush_dcache_page(page); 390 SetPageUptodate(page); 391 unlock_page(page); 392 return 0; 393 } 394 EXPORT_SYMBOL(simple_readpage); 395 396 int simple_write_begin(struct file *file, struct address_space *mapping, 397 loff_t pos, unsigned len, unsigned flags, 398 struct page **pagep, void **fsdata) 399 { 400 struct page *page; 401 pgoff_t index; 402 403 index = pos >> PAGE_CACHE_SHIFT; 404 405 page = grab_cache_page_write_begin(mapping, index, flags); 406 if (!page) 407 return -ENOMEM; 408 409 *pagep = page; 410 411 if (!PageUptodate(page) && (len != PAGE_CACHE_SIZE)) { 412 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 413 414 zero_user_segments(page, 0, from, from + len, PAGE_CACHE_SIZE); 415 } 416 return 0; 417 } 418 EXPORT_SYMBOL(simple_write_begin); 419 420 /** 421 * simple_write_end - .write_end helper for non-block-device FSes 422 * @available: See .write_end of address_space_operations 423 * @file: " 424 * @mapping: " 425 * @pos: " 426 * @len: " 427 * @copied: " 428 * @page: " 429 * @fsdata: " 430 * 431 * simple_write_end does the minimum needed for updating a page after writing is 432 * done. It has the same API signature as the .write_end of 433 * address_space_operations vector. So it can just be set onto .write_end for 434 * FSes that don't need any other processing. i_mutex is assumed to be held. 435 * Block based filesystems should use generic_write_end(). 436 * NOTE: Even though i_size might get updated by this function, mark_inode_dirty 437 * is not called, so a filesystem that actually does store data in .write_inode 438 * should extend on what's done here with a call to mark_inode_dirty() in the 439 * case that i_size has changed. 440 */ 441 int simple_write_end(struct file *file, struct address_space *mapping, 442 loff_t pos, unsigned len, unsigned copied, 443 struct page *page, void *fsdata) 444 { 445 struct inode *inode = page->mapping->host; 446 loff_t last_pos = pos + copied; 447 448 /* zero the stale part of the page if we did a short copy */ 449 if (copied < len) { 450 unsigned from = pos & (PAGE_CACHE_SIZE - 1); 451 452 zero_user(page, from + copied, len - copied); 453 } 454 455 if (!PageUptodate(page)) 456 SetPageUptodate(page); 457 /* 458 * No need to use i_size_read() here, the i_size 459 * cannot change under us because we hold the i_mutex. 460 */ 461 if (last_pos > inode->i_size) 462 i_size_write(inode, last_pos); 463 464 set_page_dirty(page); 465 unlock_page(page); 466 page_cache_release(page); 467 468 return copied; 469 } 470 EXPORT_SYMBOL(simple_write_end); 471 472 /* 473 * the inodes created here are not hashed. If you use iunique to generate 474 * unique inode values later for this filesystem, then you must take care 475 * to pass it an appropriate max_reserved value to avoid collisions. 476 */ 477 int simple_fill_super(struct super_block *s, unsigned long magic, 478 struct tree_descr *files) 479 { 480 struct inode *inode; 481 struct dentry *root; 482 struct dentry *dentry; 483 int i; 484 485 s->s_blocksize = PAGE_CACHE_SIZE; 486 s->s_blocksize_bits = PAGE_CACHE_SHIFT; 487 s->s_magic = magic; 488 s->s_op = &simple_super_operations; 489 s->s_time_gran = 1; 490 491 inode = new_inode(s); 492 if (!inode) 493 return -ENOMEM; 494 /* 495 * because the root inode is 1, the files array must not contain an 496 * entry at index 1 497 */ 498 inode->i_ino = 1; 499 inode->i_mode = S_IFDIR | 0755; 500 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 501 inode->i_op = &simple_dir_inode_operations; 502 inode->i_fop = &simple_dir_operations; 503 set_nlink(inode, 2); 504 root = d_make_root(inode); 505 if (!root) 506 return -ENOMEM; 507 for (i = 0; !files->name || files->name[0]; i++, files++) { 508 if (!files->name) 509 continue; 510 511 /* warn if it tries to conflict with the root inode */ 512 if (unlikely(i == 1)) 513 printk(KERN_WARNING "%s: %s passed in a files array" 514 "with an index of 1!\n", __func__, 515 s->s_type->name); 516 517 dentry = d_alloc_name(root, files->name); 518 if (!dentry) 519 goto out; 520 inode = new_inode(s); 521 if (!inode) { 522 dput(dentry); 523 goto out; 524 } 525 inode->i_mode = S_IFREG | files->mode; 526 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 527 inode->i_fop = files->ops; 528 inode->i_ino = i; 529 d_add(dentry, inode); 530 } 531 s->s_root = root; 532 return 0; 533 out: 534 d_genocide(root); 535 shrink_dcache_parent(root); 536 dput(root); 537 return -ENOMEM; 538 } 539 EXPORT_SYMBOL(simple_fill_super); 540 541 static DEFINE_SPINLOCK(pin_fs_lock); 542 543 int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) 544 { 545 struct vfsmount *mnt = NULL; 546 spin_lock(&pin_fs_lock); 547 if (unlikely(!*mount)) { 548 spin_unlock(&pin_fs_lock); 549 mnt = vfs_kern_mount(type, MS_KERNMOUNT, type->name, NULL); 550 if (IS_ERR(mnt)) 551 return PTR_ERR(mnt); 552 spin_lock(&pin_fs_lock); 553 if (!*mount) 554 *mount = mnt; 555 } 556 mntget(*mount); 557 ++*count; 558 spin_unlock(&pin_fs_lock); 559 mntput(mnt); 560 return 0; 561 } 562 EXPORT_SYMBOL(simple_pin_fs); 563 564 void simple_release_fs(struct vfsmount **mount, int *count) 565 { 566 struct vfsmount *mnt; 567 spin_lock(&pin_fs_lock); 568 mnt = *mount; 569 if (!--*count) 570 *mount = NULL; 571 spin_unlock(&pin_fs_lock); 572 mntput(mnt); 573 } 574 EXPORT_SYMBOL(simple_release_fs); 575 576 /** 577 * simple_read_from_buffer - copy data from the buffer to user space 578 * @to: the user space buffer to read to 579 * @count: the maximum number of bytes to read 580 * @ppos: the current position in the buffer 581 * @from: the buffer to read from 582 * @available: the size of the buffer 583 * 584 * The simple_read_from_buffer() function reads up to @count bytes from the 585 * buffer @from at offset @ppos into the user space address starting at @to. 586 * 587 * On success, the number of bytes read is returned and the offset @ppos is 588 * advanced by this number, or negative value is returned on error. 589 **/ 590 ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, 591 const void *from, size_t available) 592 { 593 loff_t pos = *ppos; 594 size_t ret; 595 596 if (pos < 0) 597 return -EINVAL; 598 if (pos >= available || !count) 599 return 0; 600 if (count > available - pos) 601 count = available - pos; 602 ret = copy_to_user(to, from + pos, count); 603 if (ret == count) 604 return -EFAULT; 605 count -= ret; 606 *ppos = pos + count; 607 return count; 608 } 609 EXPORT_SYMBOL(simple_read_from_buffer); 610 611 /** 612 * simple_write_to_buffer - copy data from user space to the buffer 613 * @to: the buffer to write to 614 * @available: the size of the buffer 615 * @ppos: the current position in the buffer 616 * @from: the user space buffer to read from 617 * @count: the maximum number of bytes to read 618 * 619 * The simple_write_to_buffer() function reads up to @count bytes from the user 620 * space address starting at @from into the buffer @to at offset @ppos. 621 * 622 * On success, the number of bytes written is returned and the offset @ppos is 623 * advanced by this number, or negative value is returned on error. 624 **/ 625 ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, 626 const void __user *from, size_t count) 627 { 628 loff_t pos = *ppos; 629 size_t res; 630 631 if (pos < 0) 632 return -EINVAL; 633 if (pos >= available || !count) 634 return 0; 635 if (count > available - pos) 636 count = available - pos; 637 res = copy_from_user(to + pos, from, count); 638 if (res == count) 639 return -EFAULT; 640 count -= res; 641 *ppos = pos + count; 642 return count; 643 } 644 EXPORT_SYMBOL(simple_write_to_buffer); 645 646 /** 647 * memory_read_from_buffer - copy data from the buffer 648 * @to: the kernel space buffer to read to 649 * @count: the maximum number of bytes to read 650 * @ppos: the current position in the buffer 651 * @from: the buffer to read from 652 * @available: the size of the buffer 653 * 654 * The memory_read_from_buffer() function reads up to @count bytes from the 655 * buffer @from at offset @ppos into the kernel space address starting at @to. 656 * 657 * On success, the number of bytes read is returned and the offset @ppos is 658 * advanced by this number, or negative value is returned on error. 659 **/ 660 ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, 661 const void *from, size_t available) 662 { 663 loff_t pos = *ppos; 664 665 if (pos < 0) 666 return -EINVAL; 667 if (pos >= available) 668 return 0; 669 if (count > available - pos) 670 count = available - pos; 671 memcpy(to, from + pos, count); 672 *ppos = pos + count; 673 674 return count; 675 } 676 EXPORT_SYMBOL(memory_read_from_buffer); 677 678 /* 679 * Transaction based IO. 680 * The file expects a single write which triggers the transaction, and then 681 * possibly a read which collects the result - which is stored in a 682 * file-local buffer. 683 */ 684 685 void simple_transaction_set(struct file *file, size_t n) 686 { 687 struct simple_transaction_argresp *ar = file->private_data; 688 689 BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); 690 691 /* 692 * The barrier ensures that ar->size will really remain zero until 693 * ar->data is ready for reading. 694 */ 695 smp_mb(); 696 ar->size = n; 697 } 698 EXPORT_SYMBOL(simple_transaction_set); 699 700 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) 701 { 702 struct simple_transaction_argresp *ar; 703 static DEFINE_SPINLOCK(simple_transaction_lock); 704 705 if (size > SIMPLE_TRANSACTION_LIMIT - 1) 706 return ERR_PTR(-EFBIG); 707 708 ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); 709 if (!ar) 710 return ERR_PTR(-ENOMEM); 711 712 spin_lock(&simple_transaction_lock); 713 714 /* only one write allowed per open */ 715 if (file->private_data) { 716 spin_unlock(&simple_transaction_lock); 717 free_page((unsigned long)ar); 718 return ERR_PTR(-EBUSY); 719 } 720 721 file->private_data = ar; 722 723 spin_unlock(&simple_transaction_lock); 724 725 if (copy_from_user(ar->data, buf, size)) 726 return ERR_PTR(-EFAULT); 727 728 return ar->data; 729 } 730 EXPORT_SYMBOL(simple_transaction_get); 731 732 ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) 733 { 734 struct simple_transaction_argresp *ar = file->private_data; 735 736 if (!ar) 737 return 0; 738 return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); 739 } 740 EXPORT_SYMBOL(simple_transaction_read); 741 742 int simple_transaction_release(struct inode *inode, struct file *file) 743 { 744 free_page((unsigned long)file->private_data); 745 return 0; 746 } 747 EXPORT_SYMBOL(simple_transaction_release); 748 749 /* Simple attribute files */ 750 751 struct simple_attr { 752 int (*get)(void *, u64 *); 753 int (*set)(void *, u64); 754 char get_buf[24]; /* enough to store a u64 and "\n\0" */ 755 char set_buf[24]; 756 void *data; 757 const char *fmt; /* format for read operation */ 758 struct mutex mutex; /* protects access to these buffers */ 759 }; 760 761 /* simple_attr_open is called by an actual attribute open file operation 762 * to set the attribute specific access operations. */ 763 int simple_attr_open(struct inode *inode, struct file *file, 764 int (*get)(void *, u64 *), int (*set)(void *, u64), 765 const char *fmt) 766 { 767 struct simple_attr *attr; 768 769 attr = kmalloc(sizeof(*attr), GFP_KERNEL); 770 if (!attr) 771 return -ENOMEM; 772 773 attr->get = get; 774 attr->set = set; 775 attr->data = inode->i_private; 776 attr->fmt = fmt; 777 mutex_init(&attr->mutex); 778 779 file->private_data = attr; 780 781 return nonseekable_open(inode, file); 782 } 783 EXPORT_SYMBOL_GPL(simple_attr_open); 784 785 int simple_attr_release(struct inode *inode, struct file *file) 786 { 787 kfree(file->private_data); 788 return 0; 789 } 790 EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ 791 792 /* read from the buffer that is filled with the get function */ 793 ssize_t simple_attr_read(struct file *file, char __user *buf, 794 size_t len, loff_t *ppos) 795 { 796 struct simple_attr *attr; 797 size_t size; 798 ssize_t ret; 799 800 attr = file->private_data; 801 802 if (!attr->get) 803 return -EACCES; 804 805 ret = mutex_lock_interruptible(&attr->mutex); 806 if (ret) 807 return ret; 808 809 if (*ppos) { /* continued read */ 810 size = strlen(attr->get_buf); 811 } else { /* first read */ 812 u64 val; 813 ret = attr->get(attr->data, &val); 814 if (ret) 815 goto out; 816 817 size = scnprintf(attr->get_buf, sizeof(attr->get_buf), 818 attr->fmt, (unsigned long long)val); 819 } 820 821 ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); 822 out: 823 mutex_unlock(&attr->mutex); 824 return ret; 825 } 826 EXPORT_SYMBOL_GPL(simple_attr_read); 827 828 /* interpret the buffer as a number to call the set function with */ 829 ssize_t simple_attr_write(struct file *file, const char __user *buf, 830 size_t len, loff_t *ppos) 831 { 832 struct simple_attr *attr; 833 u64 val; 834 size_t size; 835 ssize_t ret; 836 837 attr = file->private_data; 838 if (!attr->set) 839 return -EACCES; 840 841 ret = mutex_lock_interruptible(&attr->mutex); 842 if (ret) 843 return ret; 844 845 ret = -EFAULT; 846 size = min(sizeof(attr->set_buf) - 1, len); 847 if (copy_from_user(attr->set_buf, buf, size)) 848 goto out; 849 850 attr->set_buf[size] = '\0'; 851 val = simple_strtoll(attr->set_buf, NULL, 0); 852 ret = attr->set(attr->data, val); 853 if (ret == 0) 854 ret = len; /* on success, claim we got the whole input */ 855 out: 856 mutex_unlock(&attr->mutex); 857 return ret; 858 } 859 EXPORT_SYMBOL_GPL(simple_attr_write); 860 861 /** 862 * generic_fh_to_dentry - generic helper for the fh_to_dentry export operation 863 * @sb: filesystem to do the file handle conversion on 864 * @fid: file handle to convert 865 * @fh_len: length of the file handle in bytes 866 * @fh_type: type of file handle 867 * @get_inode: filesystem callback to retrieve inode 868 * 869 * This function decodes @fid as long as it has one of the well-known 870 * Linux filehandle types and calls @get_inode on it to retrieve the 871 * inode for the object specified in the file handle. 872 */ 873 struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, 874 int fh_len, int fh_type, struct inode *(*get_inode) 875 (struct super_block *sb, u64 ino, u32 gen)) 876 { 877 struct inode *inode = NULL; 878 879 if (fh_len < 2) 880 return NULL; 881 882 switch (fh_type) { 883 case FILEID_INO32_GEN: 884 case FILEID_INO32_GEN_PARENT: 885 inode = get_inode(sb, fid->i32.ino, fid->i32.gen); 886 break; 887 } 888 889 return d_obtain_alias(inode); 890 } 891 EXPORT_SYMBOL_GPL(generic_fh_to_dentry); 892 893 /** 894 * generic_fh_to_parent - generic helper for the fh_to_parent export operation 895 * @sb: filesystem to do the file handle conversion on 896 * @fid: file handle to convert 897 * @fh_len: length of the file handle in bytes 898 * @fh_type: type of file handle 899 * @get_inode: filesystem callback to retrieve inode 900 * 901 * This function decodes @fid as long as it has one of the well-known 902 * Linux filehandle types and calls @get_inode on it to retrieve the 903 * inode for the _parent_ object specified in the file handle if it 904 * is specified in the file handle, or NULL otherwise. 905 */ 906 struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, 907 int fh_len, int fh_type, struct inode *(*get_inode) 908 (struct super_block *sb, u64 ino, u32 gen)) 909 { 910 struct inode *inode = NULL; 911 912 if (fh_len <= 2) 913 return NULL; 914 915 switch (fh_type) { 916 case FILEID_INO32_GEN_PARENT: 917 inode = get_inode(sb, fid->i32.parent_ino, 918 (fh_len > 3 ? fid->i32.parent_gen : 0)); 919 break; 920 } 921 922 return d_obtain_alias(inode); 923 } 924 EXPORT_SYMBOL_GPL(generic_fh_to_parent); 925 926 /** 927 * __generic_file_fsync - generic fsync implementation for simple filesystems 928 * 929 * @file: file to synchronize 930 * @start: start offset in bytes 931 * @end: end offset in bytes (inclusive) 932 * @datasync: only synchronize essential metadata if true 933 * 934 * This is a generic implementation of the fsync method for simple 935 * filesystems which track all non-inode metadata in the buffers list 936 * hanging off the address_space structure. 937 */ 938 int __generic_file_fsync(struct file *file, loff_t start, loff_t end, 939 int datasync) 940 { 941 struct inode *inode = file->f_mapping->host; 942 int err; 943 int ret; 944 945 err = filemap_write_and_wait_range(inode->i_mapping, start, end); 946 if (err) 947 return err; 948 949 mutex_lock(&inode->i_mutex); 950 ret = sync_mapping_buffers(inode->i_mapping); 951 if (!(inode->i_state & I_DIRTY_ALL)) 952 goto out; 953 if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) 954 goto out; 955 956 err = sync_inode_metadata(inode, 1); 957 if (ret == 0) 958 ret = err; 959 960 out: 961 mutex_unlock(&inode->i_mutex); 962 return ret; 963 } 964 EXPORT_SYMBOL(__generic_file_fsync); 965 966 /** 967 * generic_file_fsync - generic fsync implementation for simple filesystems 968 * with flush 969 * @file: file to synchronize 970 * @start: start offset in bytes 971 * @end: end offset in bytes (inclusive) 972 * @datasync: only synchronize essential metadata if true 973 * 974 */ 975 976 int generic_file_fsync(struct file *file, loff_t start, loff_t end, 977 int datasync) 978 { 979 struct inode *inode = file->f_mapping->host; 980 int err; 981 982 err = __generic_file_fsync(file, start, end, datasync); 983 if (err) 984 return err; 985 return blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL); 986 } 987 EXPORT_SYMBOL(generic_file_fsync); 988 989 /** 990 * generic_check_addressable - Check addressability of file system 991 * @blocksize_bits: log of file system block size 992 * @num_blocks: number of blocks in file system 993 * 994 * Determine whether a file system with @num_blocks blocks (and a 995 * block size of 2**@blocksize_bits) is addressable by the sector_t 996 * and page cache of the system. Return 0 if so and -EFBIG otherwise. 997 */ 998 int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) 999 { 1000 u64 last_fs_block = num_blocks - 1; 1001 u64 last_fs_page = 1002 last_fs_block >> (PAGE_CACHE_SHIFT - blocksize_bits); 1003 1004 if (unlikely(num_blocks == 0)) 1005 return 0; 1006 1007 if ((blocksize_bits < 9) || (blocksize_bits > PAGE_CACHE_SHIFT)) 1008 return -EINVAL; 1009 1010 if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || 1011 (last_fs_page > (pgoff_t)(~0ULL))) { 1012 return -EFBIG; 1013 } 1014 return 0; 1015 } 1016 EXPORT_SYMBOL(generic_check_addressable); 1017 1018 /* 1019 * No-op implementation of ->fsync for in-memory filesystems. 1020 */ 1021 int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) 1022 { 1023 return 0; 1024 } 1025 EXPORT_SYMBOL(noop_fsync); 1026 1027 void kfree_put_link(struct dentry *dentry, struct nameidata *nd, 1028 void *cookie) 1029 { 1030 char *s = nd_get_link(nd); 1031 if (!IS_ERR(s)) 1032 kfree(s); 1033 } 1034 EXPORT_SYMBOL(kfree_put_link); 1035 1036 /* 1037 * nop .set_page_dirty method so that people can use .page_mkwrite on 1038 * anon inodes. 1039 */ 1040 static int anon_set_page_dirty(struct page *page) 1041 { 1042 return 0; 1043 }; 1044 1045 /* 1046 * A single inode exists for all anon_inode files. Contrary to pipes, 1047 * anon_inode inodes have no associated per-instance data, so we need 1048 * only allocate one of them. 1049 */ 1050 struct inode *alloc_anon_inode(struct super_block *s) 1051 { 1052 static const struct address_space_operations anon_aops = { 1053 .set_page_dirty = anon_set_page_dirty, 1054 }; 1055 struct inode *inode = new_inode_pseudo(s); 1056 1057 if (!inode) 1058 return ERR_PTR(-ENOMEM); 1059 1060 inode->i_ino = get_next_ino(); 1061 inode->i_mapping->a_ops = &anon_aops; 1062 1063 /* 1064 * Mark the inode dirty from the very beginning, 1065 * that way it will never be moved to the dirty 1066 * list because mark_inode_dirty() will think 1067 * that it already _is_ on the dirty list. 1068 */ 1069 inode->i_state = I_DIRTY; 1070 inode->i_mode = S_IRUSR | S_IWUSR; 1071 inode->i_uid = current_fsuid(); 1072 inode->i_gid = current_fsgid(); 1073 inode->i_flags |= S_PRIVATE; 1074 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1075 return inode; 1076 } 1077 EXPORT_SYMBOL(alloc_anon_inode); 1078 1079 /** 1080 * simple_nosetlease - generic helper for prohibiting leases 1081 * @filp: file pointer 1082 * @arg: type of lease to obtain 1083 * @flp: new lease supplied for insertion 1084 * @priv: private data for lm_setup operation 1085 * 1086 * Generic helper for filesystems that do not wish to allow leases to be set. 1087 * All arguments are ignored and it just returns -EINVAL. 1088 */ 1089 int 1090 simple_nosetlease(struct file *filp, long arg, struct file_lock **flp, 1091 void **priv) 1092 { 1093 return -EINVAL; 1094 } 1095 EXPORT_SYMBOL(simple_nosetlease); 1096