1 /* 2 * linux/drivers/block/loop.c 3 * 4 * Written by Theodore Ts'o, 3/29/93 5 * 6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is 7 * permitted under the GNU General Public License. 8 * 9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993 10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996 11 * 12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994 13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996 14 * 15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997 16 * 17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998 18 * 19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998 20 * 21 * Loadable modules and other fixes by AK, 1998 22 * 23 * Make real block number available to downstream transfer functions, enables 24 * CBC (and relatives) mode encryption requiring unique IVs per data block. 25 * Reed H. Petty, rhp@draper.net 26 * 27 * Maximum number of loop devices now dynamic via max_loop module parameter. 28 * Russell Kroll <rkroll@exploits.org> 19990701 29 * 30 * Maximum number of loop devices when compiled-in now selectable by passing 31 * max_loop=<1-255> to the kernel on boot. 32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999 33 * 34 * Completely rewrite request handling to be make_request_fn style and 35 * non blocking, pushing work to a helper thread. Lots of fixes from 36 * Al Viro too. 37 * Jens Axboe <axboe@suse.de>, Nov 2000 38 * 39 * Support up to 256 loop devices 40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002 41 * 42 * Support for falling back on the write file operation when the address space 43 * operations write_begin is not available on the backing filesystem. 44 * Anton Altaparmakov, 16 Feb 2005 45 * 46 * Still To Fix: 47 * - Advisory locking is ignored here. 48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN 49 * 50 */ 51 52 #include <linux/module.h> 53 #include <linux/moduleparam.h> 54 #include <linux/sched.h> 55 #include <linux/fs.h> 56 #include <linux/file.h> 57 #include <linux/stat.h> 58 #include <linux/errno.h> 59 #include <linux/major.h> 60 #include <linux/wait.h> 61 #include <linux/blkdev.h> 62 #include <linux/blkpg.h> 63 #include <linux/init.h> 64 #include <linux/swap.h> 65 #include <linux/slab.h> 66 #include <linux/loop.h> 67 #include <linux/compat.h> 68 #include <linux/suspend.h> 69 #include <linux/freezer.h> 70 #include <linux/mutex.h> 71 #include <linux/writeback.h> 72 #include <linux/buffer_head.h> /* for invalidate_bdev() */ 73 #include <linux/completion.h> 74 #include <linux/highmem.h> 75 #include <linux/kthread.h> 76 #include <linux/splice.h> 77 #include <linux/sysfs.h> 78 79 #include <asm/uaccess.h> 80 81 static LIST_HEAD(loop_devices); 82 static DEFINE_MUTEX(loop_devices_mutex); 83 84 static int max_part; 85 static int part_shift; 86 87 /* 88 * Transfer functions 89 */ 90 static int transfer_none(struct loop_device *lo, int cmd, 91 struct page *raw_page, unsigned raw_off, 92 struct page *loop_page, unsigned loop_off, 93 int size, sector_t real_block) 94 { 95 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off; 96 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off; 97 98 if (cmd == READ) 99 memcpy(loop_buf, raw_buf, size); 100 else 101 memcpy(raw_buf, loop_buf, size); 102 103 kunmap_atomic(loop_buf, KM_USER1); 104 kunmap_atomic(raw_buf, KM_USER0); 105 cond_resched(); 106 return 0; 107 } 108 109 static int transfer_xor(struct loop_device *lo, int cmd, 110 struct page *raw_page, unsigned raw_off, 111 struct page *loop_page, unsigned loop_off, 112 int size, sector_t real_block) 113 { 114 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off; 115 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off; 116 char *in, *out, *key; 117 int i, keysize; 118 119 if (cmd == READ) { 120 in = raw_buf; 121 out = loop_buf; 122 } else { 123 in = loop_buf; 124 out = raw_buf; 125 } 126 127 key = lo->lo_encrypt_key; 128 keysize = lo->lo_encrypt_key_size; 129 for (i = 0; i < size; i++) 130 *out++ = *in++ ^ key[(i & 511) % keysize]; 131 132 kunmap_atomic(loop_buf, KM_USER1); 133 kunmap_atomic(raw_buf, KM_USER0); 134 cond_resched(); 135 return 0; 136 } 137 138 static int xor_init(struct loop_device *lo, const struct loop_info64 *info) 139 { 140 if (unlikely(info->lo_encrypt_key_size <= 0)) 141 return -EINVAL; 142 return 0; 143 } 144 145 static struct loop_func_table none_funcs = { 146 .number = LO_CRYPT_NONE, 147 .transfer = transfer_none, 148 }; 149 150 static struct loop_func_table xor_funcs = { 151 .number = LO_CRYPT_XOR, 152 .transfer = transfer_xor, 153 .init = xor_init 154 }; 155 156 /* xfer_funcs[0] is special - its release function is never called */ 157 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = { 158 &none_funcs, 159 &xor_funcs 160 }; 161 162 static loff_t get_loop_size(struct loop_device *lo, struct file *file) 163 { 164 loff_t size, offset, loopsize; 165 166 /* Compute loopsize in bytes */ 167 size = i_size_read(file->f_mapping->host); 168 offset = lo->lo_offset; 169 loopsize = size - offset; 170 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize) 171 loopsize = lo->lo_sizelimit; 172 173 /* 174 * Unfortunately, if we want to do I/O on the device, 175 * the number of 512-byte sectors has to fit into a sector_t. 176 */ 177 return loopsize >> 9; 178 } 179 180 static int 181 figure_loop_size(struct loop_device *lo) 182 { 183 loff_t size = get_loop_size(lo, lo->lo_backing_file); 184 sector_t x = (sector_t)size; 185 186 if (unlikely((loff_t)x != size)) 187 return -EFBIG; 188 189 set_capacity(lo->lo_disk, x); 190 return 0; 191 } 192 193 static inline int 194 lo_do_transfer(struct loop_device *lo, int cmd, 195 struct page *rpage, unsigned roffs, 196 struct page *lpage, unsigned loffs, 197 int size, sector_t rblock) 198 { 199 if (unlikely(!lo->transfer)) 200 return 0; 201 202 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); 203 } 204 205 /** 206 * do_lo_send_aops - helper for writing data to a loop device 207 * 208 * This is the fast version for backing filesystems which implement the address 209 * space operations write_begin and write_end. 210 */ 211 static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec, 212 loff_t pos, struct page *unused) 213 { 214 struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */ 215 struct address_space *mapping = file->f_mapping; 216 pgoff_t index; 217 unsigned offset, bv_offs; 218 int len, ret; 219 220 mutex_lock(&mapping->host->i_mutex); 221 index = pos >> PAGE_CACHE_SHIFT; 222 offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1); 223 bv_offs = bvec->bv_offset; 224 len = bvec->bv_len; 225 while (len > 0) { 226 sector_t IV; 227 unsigned size, copied; 228 int transfer_result; 229 struct page *page; 230 void *fsdata; 231 232 IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9); 233 size = PAGE_CACHE_SIZE - offset; 234 if (size > len) 235 size = len; 236 237 ret = pagecache_write_begin(file, mapping, pos, size, 0, 238 &page, &fsdata); 239 if (ret) 240 goto fail; 241 242 file_update_time(file); 243 244 transfer_result = lo_do_transfer(lo, WRITE, page, offset, 245 bvec->bv_page, bv_offs, size, IV); 246 copied = size; 247 if (unlikely(transfer_result)) 248 copied = 0; 249 250 ret = pagecache_write_end(file, mapping, pos, size, copied, 251 page, fsdata); 252 if (ret < 0 || ret != copied) 253 goto fail; 254 255 if (unlikely(transfer_result)) 256 goto fail; 257 258 bv_offs += copied; 259 len -= copied; 260 offset = 0; 261 index++; 262 pos += copied; 263 } 264 ret = 0; 265 out: 266 mutex_unlock(&mapping->host->i_mutex); 267 return ret; 268 fail: 269 ret = -1; 270 goto out; 271 } 272 273 /** 274 * __do_lo_send_write - helper for writing data to a loop device 275 * 276 * This helper just factors out common code between do_lo_send_direct_write() 277 * and do_lo_send_write(). 278 */ 279 static int __do_lo_send_write(struct file *file, 280 u8 *buf, const int len, loff_t pos) 281 { 282 ssize_t bw; 283 mm_segment_t old_fs = get_fs(); 284 285 set_fs(get_ds()); 286 bw = file->f_op->write(file, buf, len, &pos); 287 set_fs(old_fs); 288 if (likely(bw == len)) 289 return 0; 290 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n", 291 (unsigned long long)pos, len); 292 if (bw >= 0) 293 bw = -EIO; 294 return bw; 295 } 296 297 /** 298 * do_lo_send_direct_write - helper for writing data to a loop device 299 * 300 * This is the fast, non-transforming version for backing filesystems which do 301 * not implement the address space operations write_begin and write_end. 302 * It uses the write file operation which should be present on all writeable 303 * filesystems. 304 */ 305 static int do_lo_send_direct_write(struct loop_device *lo, 306 struct bio_vec *bvec, loff_t pos, struct page *page) 307 { 308 ssize_t bw = __do_lo_send_write(lo->lo_backing_file, 309 kmap(bvec->bv_page) + bvec->bv_offset, 310 bvec->bv_len, pos); 311 kunmap(bvec->bv_page); 312 cond_resched(); 313 return bw; 314 } 315 316 /** 317 * do_lo_send_write - helper for writing data to a loop device 318 * 319 * This is the slow, transforming version for filesystems which do not 320 * implement the address space operations write_begin and write_end. It 321 * uses the write file operation which should be present on all writeable 322 * filesystems. 323 * 324 * Using fops->write is slower than using aops->{prepare,commit}_write in the 325 * transforming case because we need to double buffer the data as we cannot do 326 * the transformations in place as we do not have direct access to the 327 * destination pages of the backing file. 328 */ 329 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec, 330 loff_t pos, struct page *page) 331 { 332 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page, 333 bvec->bv_offset, bvec->bv_len, pos >> 9); 334 if (likely(!ret)) 335 return __do_lo_send_write(lo->lo_backing_file, 336 page_address(page), bvec->bv_len, 337 pos); 338 printk(KERN_ERR "loop: Transfer error at byte offset %llu, " 339 "length %i.\n", (unsigned long long)pos, bvec->bv_len); 340 if (ret > 0) 341 ret = -EIO; 342 return ret; 343 } 344 345 static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos) 346 { 347 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t, 348 struct page *page); 349 struct bio_vec *bvec; 350 struct page *page = NULL; 351 int i, ret = 0; 352 353 do_lo_send = do_lo_send_aops; 354 if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) { 355 do_lo_send = do_lo_send_direct_write; 356 if (lo->transfer != transfer_none) { 357 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM); 358 if (unlikely(!page)) 359 goto fail; 360 kmap(page); 361 do_lo_send = do_lo_send_write; 362 } 363 } 364 bio_for_each_segment(bvec, bio, i) { 365 ret = do_lo_send(lo, bvec, pos, page); 366 if (ret < 0) 367 break; 368 pos += bvec->bv_len; 369 } 370 if (page) { 371 kunmap(page); 372 __free_page(page); 373 } 374 out: 375 return ret; 376 fail: 377 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n"); 378 ret = -ENOMEM; 379 goto out; 380 } 381 382 struct lo_read_data { 383 struct loop_device *lo; 384 struct page *page; 385 unsigned offset; 386 int bsize; 387 }; 388 389 static int 390 lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, 391 struct splice_desc *sd) 392 { 393 struct lo_read_data *p = sd->u.data; 394 struct loop_device *lo = p->lo; 395 struct page *page = buf->page; 396 sector_t IV; 397 int size; 398 399 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) + 400 (buf->offset >> 9); 401 size = sd->len; 402 if (size > p->bsize) 403 size = p->bsize; 404 405 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) { 406 printk(KERN_ERR "loop: transfer error block %ld\n", 407 page->index); 408 size = -EINVAL; 409 } 410 411 flush_dcache_page(p->page); 412 413 if (size > 0) 414 p->offset += size; 415 416 return size; 417 } 418 419 static int 420 lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd) 421 { 422 return __splice_from_pipe(pipe, sd, lo_splice_actor); 423 } 424 425 static int 426 do_lo_receive(struct loop_device *lo, 427 struct bio_vec *bvec, int bsize, loff_t pos) 428 { 429 struct lo_read_data cookie; 430 struct splice_desc sd; 431 struct file *file; 432 long retval; 433 434 cookie.lo = lo; 435 cookie.page = bvec->bv_page; 436 cookie.offset = bvec->bv_offset; 437 cookie.bsize = bsize; 438 439 sd.len = 0; 440 sd.total_len = bvec->bv_len; 441 sd.flags = 0; 442 sd.pos = pos; 443 sd.u.data = &cookie; 444 445 file = lo->lo_backing_file; 446 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor); 447 448 if (retval < 0) 449 return retval; 450 451 return 0; 452 } 453 454 static int 455 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos) 456 { 457 struct bio_vec *bvec; 458 int i, ret = 0; 459 460 bio_for_each_segment(bvec, bio, i) { 461 ret = do_lo_receive(lo, bvec, bsize, pos); 462 if (ret < 0) 463 break; 464 pos += bvec->bv_len; 465 } 466 return ret; 467 } 468 469 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio) 470 { 471 loff_t pos; 472 int ret; 473 474 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset; 475 476 if (bio_rw(bio) == WRITE) { 477 struct file *file = lo->lo_backing_file; 478 479 if (bio->bi_rw & REQ_FLUSH) { 480 ret = vfs_fsync(file, 0); 481 if (unlikely(ret && ret != -EINVAL)) { 482 ret = -EIO; 483 goto out; 484 } 485 } 486 487 ret = lo_send(lo, bio, pos); 488 489 if ((bio->bi_rw & REQ_FUA) && !ret) { 490 ret = vfs_fsync(file, 0); 491 if (unlikely(ret && ret != -EINVAL)) 492 ret = -EIO; 493 } 494 } else 495 ret = lo_receive(lo, bio, lo->lo_blocksize, pos); 496 497 out: 498 return ret; 499 } 500 501 /* 502 * Add bio to back of pending list 503 */ 504 static void loop_add_bio(struct loop_device *lo, struct bio *bio) 505 { 506 bio_list_add(&lo->lo_bio_list, bio); 507 } 508 509 /* 510 * Grab first pending buffer 511 */ 512 static struct bio *loop_get_bio(struct loop_device *lo) 513 { 514 return bio_list_pop(&lo->lo_bio_list); 515 } 516 517 static int loop_make_request(struct request_queue *q, struct bio *old_bio) 518 { 519 struct loop_device *lo = q->queuedata; 520 int rw = bio_rw(old_bio); 521 522 if (rw == READA) 523 rw = READ; 524 525 BUG_ON(!lo || (rw != READ && rw != WRITE)); 526 527 spin_lock_irq(&lo->lo_lock); 528 if (lo->lo_state != Lo_bound) 529 goto out; 530 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY))) 531 goto out; 532 loop_add_bio(lo, old_bio); 533 wake_up(&lo->lo_event); 534 spin_unlock_irq(&lo->lo_lock); 535 return 0; 536 537 out: 538 spin_unlock_irq(&lo->lo_lock); 539 bio_io_error(old_bio); 540 return 0; 541 } 542 543 struct switch_request { 544 struct file *file; 545 struct completion wait; 546 }; 547 548 static void do_loop_switch(struct loop_device *, struct switch_request *); 549 550 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio) 551 { 552 if (unlikely(!bio->bi_bdev)) { 553 do_loop_switch(lo, bio->bi_private); 554 bio_put(bio); 555 } else { 556 int ret = do_bio_filebacked(lo, bio); 557 bio_endio(bio, ret); 558 } 559 } 560 561 /* 562 * worker thread that handles reads/writes to file backed loop devices, 563 * to avoid blocking in our make_request_fn. it also does loop decrypting 564 * on reads for block backed loop, as that is too heavy to do from 565 * b_end_io context where irqs may be disabled. 566 * 567 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before 568 * calling kthread_stop(). Therefore once kthread_should_stop() is 569 * true, make_request will not place any more requests. Therefore 570 * once kthread_should_stop() is true and lo_bio is NULL, we are 571 * done with the loop. 572 */ 573 static int loop_thread(void *data) 574 { 575 struct loop_device *lo = data; 576 struct bio *bio; 577 578 set_user_nice(current, -20); 579 580 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) { 581 582 wait_event_interruptible(lo->lo_event, 583 !bio_list_empty(&lo->lo_bio_list) || 584 kthread_should_stop()); 585 586 if (bio_list_empty(&lo->lo_bio_list)) 587 continue; 588 spin_lock_irq(&lo->lo_lock); 589 bio = loop_get_bio(lo); 590 spin_unlock_irq(&lo->lo_lock); 591 592 BUG_ON(!bio); 593 loop_handle_bio(lo, bio); 594 } 595 596 return 0; 597 } 598 599 /* 600 * loop_switch performs the hard work of switching a backing store. 601 * First it needs to flush existing IO, it does this by sending a magic 602 * BIO down the pipe. The completion of this BIO does the actual switch. 603 */ 604 static int loop_switch(struct loop_device *lo, struct file *file) 605 { 606 struct switch_request w; 607 struct bio *bio = bio_alloc(GFP_KERNEL, 0); 608 if (!bio) 609 return -ENOMEM; 610 init_completion(&w.wait); 611 w.file = file; 612 bio->bi_private = &w; 613 bio->bi_bdev = NULL; 614 loop_make_request(lo->lo_queue, bio); 615 wait_for_completion(&w.wait); 616 return 0; 617 } 618 619 /* 620 * Helper to flush the IOs in loop, but keeping loop thread running 621 */ 622 static int loop_flush(struct loop_device *lo) 623 { 624 /* loop not yet configured, no running thread, nothing to flush */ 625 if (!lo->lo_thread) 626 return 0; 627 628 return loop_switch(lo, NULL); 629 } 630 631 /* 632 * Do the actual switch; called from the BIO completion routine 633 */ 634 static void do_loop_switch(struct loop_device *lo, struct switch_request *p) 635 { 636 struct file *file = p->file; 637 struct file *old_file = lo->lo_backing_file; 638 struct address_space *mapping; 639 640 /* if no new file, only flush of queued bios requested */ 641 if (!file) 642 goto out; 643 644 mapping = file->f_mapping; 645 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); 646 lo->lo_backing_file = file; 647 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ? 648 mapping->host->i_bdev->bd_block_size : PAGE_SIZE; 649 lo->old_gfp_mask = mapping_gfp_mask(mapping); 650 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 651 out: 652 complete(&p->wait); 653 } 654 655 656 /* 657 * loop_change_fd switched the backing store of a loopback device to 658 * a new file. This is useful for operating system installers to free up 659 * the original file and in High Availability environments to switch to 660 * an alternative location for the content in case of server meltdown. 661 * This can only work if the loop device is used read-only, and if the 662 * new backing store is the same size and type as the old backing store. 663 */ 664 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 665 unsigned int arg) 666 { 667 struct file *file, *old_file; 668 struct inode *inode; 669 int error; 670 671 error = -ENXIO; 672 if (lo->lo_state != Lo_bound) 673 goto out; 674 675 /* the loop device has to be read-only */ 676 error = -EINVAL; 677 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) 678 goto out; 679 680 error = -EBADF; 681 file = fget(arg); 682 if (!file) 683 goto out; 684 685 inode = file->f_mapping->host; 686 old_file = lo->lo_backing_file; 687 688 error = -EINVAL; 689 690 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 691 goto out_putf; 692 693 /* size of the new backing store needs to be the same */ 694 if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) 695 goto out_putf; 696 697 /* and ... switch */ 698 error = loop_switch(lo, file); 699 if (error) 700 goto out_putf; 701 702 fput(old_file); 703 if (max_part > 0) 704 ioctl_by_bdev(bdev, BLKRRPART, 0); 705 return 0; 706 707 out_putf: 708 fput(file); 709 out: 710 return error; 711 } 712 713 static inline int is_loop_device(struct file *file) 714 { 715 struct inode *i = file->f_mapping->host; 716 717 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; 718 } 719 720 /* loop sysfs attributes */ 721 722 static ssize_t loop_attr_show(struct device *dev, char *page, 723 ssize_t (*callback)(struct loop_device *, char *)) 724 { 725 struct loop_device *l, *lo = NULL; 726 727 mutex_lock(&loop_devices_mutex); 728 list_for_each_entry(l, &loop_devices, lo_list) 729 if (disk_to_dev(l->lo_disk) == dev) { 730 lo = l; 731 break; 732 } 733 mutex_unlock(&loop_devices_mutex); 734 735 return lo ? callback(lo, page) : -EIO; 736 } 737 738 #define LOOP_ATTR_RO(_name) \ 739 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ 740 static ssize_t loop_attr_do_show_##_name(struct device *d, \ 741 struct device_attribute *attr, char *b) \ 742 { \ 743 return loop_attr_show(d, b, loop_attr_##_name##_show); \ 744 } \ 745 static struct device_attribute loop_attr_##_name = \ 746 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL); 747 748 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) 749 { 750 ssize_t ret; 751 char *p = NULL; 752 753 mutex_lock(&lo->lo_ctl_mutex); 754 if (lo->lo_backing_file) 755 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1); 756 mutex_unlock(&lo->lo_ctl_mutex); 757 758 if (IS_ERR_OR_NULL(p)) 759 ret = PTR_ERR(p); 760 else { 761 ret = strlen(p); 762 memmove(buf, p, ret); 763 buf[ret++] = '\n'; 764 buf[ret] = 0; 765 } 766 767 return ret; 768 } 769 770 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) 771 { 772 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset); 773 } 774 775 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) 776 { 777 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); 778 } 779 780 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 781 { 782 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); 783 784 return sprintf(buf, "%s\n", autoclear ? "1" : "0"); 785 } 786 787 LOOP_ATTR_RO(backing_file); 788 LOOP_ATTR_RO(offset); 789 LOOP_ATTR_RO(sizelimit); 790 LOOP_ATTR_RO(autoclear); 791 792 static struct attribute *loop_attrs[] = { 793 &loop_attr_backing_file.attr, 794 &loop_attr_offset.attr, 795 &loop_attr_sizelimit.attr, 796 &loop_attr_autoclear.attr, 797 NULL, 798 }; 799 800 static struct attribute_group loop_attribute_group = { 801 .name = "loop", 802 .attrs= loop_attrs, 803 }; 804 805 static int loop_sysfs_init(struct loop_device *lo) 806 { 807 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, 808 &loop_attribute_group); 809 } 810 811 static void loop_sysfs_exit(struct loop_device *lo) 812 { 813 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, 814 &loop_attribute_group); 815 } 816 817 static int loop_set_fd(struct loop_device *lo, fmode_t mode, 818 struct block_device *bdev, unsigned int arg) 819 { 820 struct file *file, *f; 821 struct inode *inode; 822 struct address_space *mapping; 823 unsigned lo_blocksize; 824 int lo_flags = 0; 825 int error; 826 loff_t size; 827 828 /* This is safe, since we have a reference from open(). */ 829 __module_get(THIS_MODULE); 830 831 error = -EBADF; 832 file = fget(arg); 833 if (!file) 834 goto out; 835 836 error = -EBUSY; 837 if (lo->lo_state != Lo_unbound) 838 goto out_putf; 839 840 /* Avoid recursion */ 841 f = file; 842 while (is_loop_device(f)) { 843 struct loop_device *l; 844 845 if (f->f_mapping->host->i_bdev == bdev) 846 goto out_putf; 847 848 l = f->f_mapping->host->i_bdev->bd_disk->private_data; 849 if (l->lo_state == Lo_unbound) { 850 error = -EINVAL; 851 goto out_putf; 852 } 853 f = l->lo_backing_file; 854 } 855 856 mapping = file->f_mapping; 857 inode = mapping->host; 858 859 if (!(file->f_mode & FMODE_WRITE)) 860 lo_flags |= LO_FLAGS_READ_ONLY; 861 862 error = -EINVAL; 863 if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) { 864 const struct address_space_operations *aops = mapping->a_ops; 865 866 if (aops->write_begin) 867 lo_flags |= LO_FLAGS_USE_AOPS; 868 if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write) 869 lo_flags |= LO_FLAGS_READ_ONLY; 870 871 lo_blocksize = S_ISBLK(inode->i_mode) ? 872 inode->i_bdev->bd_block_size : PAGE_SIZE; 873 874 error = 0; 875 } else { 876 goto out_putf; 877 } 878 879 size = get_loop_size(lo, file); 880 881 if ((loff_t)(sector_t)size != size) { 882 error = -EFBIG; 883 goto out_putf; 884 } 885 886 if (!(mode & FMODE_WRITE)) 887 lo_flags |= LO_FLAGS_READ_ONLY; 888 889 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); 890 891 lo->lo_blocksize = lo_blocksize; 892 lo->lo_device = bdev; 893 lo->lo_flags = lo_flags; 894 lo->lo_backing_file = file; 895 lo->transfer = transfer_none; 896 lo->ioctl = NULL; 897 lo->lo_sizelimit = 0; 898 lo->old_gfp_mask = mapping_gfp_mask(mapping); 899 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 900 901 bio_list_init(&lo->lo_bio_list); 902 903 /* 904 * set queue make_request_fn, and add limits based on lower level 905 * device 906 */ 907 blk_queue_make_request(lo->lo_queue, loop_make_request); 908 lo->lo_queue->queuedata = lo; 909 910 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) 911 blk_queue_flush(lo->lo_queue, REQ_FLUSH); 912 913 set_capacity(lo->lo_disk, size); 914 bd_set_size(bdev, size << 9); 915 loop_sysfs_init(lo); 916 /* let user-space know about the new size */ 917 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 918 919 set_blocksize(bdev, lo_blocksize); 920 921 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d", 922 lo->lo_number); 923 if (IS_ERR(lo->lo_thread)) { 924 error = PTR_ERR(lo->lo_thread); 925 goto out_clr; 926 } 927 lo->lo_state = Lo_bound; 928 wake_up_process(lo->lo_thread); 929 if (max_part > 0) 930 ioctl_by_bdev(bdev, BLKRRPART, 0); 931 return 0; 932 933 out_clr: 934 loop_sysfs_exit(lo); 935 lo->lo_thread = NULL; 936 lo->lo_device = NULL; 937 lo->lo_backing_file = NULL; 938 lo->lo_flags = 0; 939 set_capacity(lo->lo_disk, 0); 940 invalidate_bdev(bdev); 941 bd_set_size(bdev, 0); 942 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 943 mapping_set_gfp_mask(mapping, lo->old_gfp_mask); 944 lo->lo_state = Lo_unbound; 945 out_putf: 946 fput(file); 947 out: 948 /* This is safe: open() is still holding a reference. */ 949 module_put(THIS_MODULE); 950 return error; 951 } 952 953 static int 954 loop_release_xfer(struct loop_device *lo) 955 { 956 int err = 0; 957 struct loop_func_table *xfer = lo->lo_encryption; 958 959 if (xfer) { 960 if (xfer->release) 961 err = xfer->release(lo); 962 lo->transfer = NULL; 963 lo->lo_encryption = NULL; 964 module_put(xfer->owner); 965 } 966 return err; 967 } 968 969 static int 970 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 971 const struct loop_info64 *i) 972 { 973 int err = 0; 974 975 if (xfer) { 976 struct module *owner = xfer->owner; 977 978 if (!try_module_get(owner)) 979 return -EINVAL; 980 if (xfer->init) 981 err = xfer->init(lo, i); 982 if (err) 983 module_put(owner); 984 else 985 lo->lo_encryption = xfer; 986 } 987 return err; 988 } 989 990 static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev) 991 { 992 struct file *filp = lo->lo_backing_file; 993 gfp_t gfp = lo->old_gfp_mask; 994 995 if (lo->lo_state != Lo_bound) 996 return -ENXIO; 997 998 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */ 999 return -EBUSY; 1000 1001 if (filp == NULL) 1002 return -EINVAL; 1003 1004 spin_lock_irq(&lo->lo_lock); 1005 lo->lo_state = Lo_rundown; 1006 spin_unlock_irq(&lo->lo_lock); 1007 1008 kthread_stop(lo->lo_thread); 1009 1010 lo->lo_backing_file = NULL; 1011 1012 loop_release_xfer(lo); 1013 lo->transfer = NULL; 1014 lo->ioctl = NULL; 1015 lo->lo_device = NULL; 1016 lo->lo_encryption = NULL; 1017 lo->lo_offset = 0; 1018 lo->lo_sizelimit = 0; 1019 lo->lo_encrypt_key_size = 0; 1020 lo->lo_flags = 0; 1021 lo->lo_thread = NULL; 1022 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); 1023 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); 1024 memset(lo->lo_file_name, 0, LO_NAME_SIZE); 1025 if (bdev) 1026 invalidate_bdev(bdev); 1027 set_capacity(lo->lo_disk, 0); 1028 loop_sysfs_exit(lo); 1029 if (bdev) { 1030 bd_set_size(bdev, 0); 1031 /* let user-space know about this change */ 1032 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 1033 } 1034 mapping_set_gfp_mask(filp->f_mapping, gfp); 1035 lo->lo_state = Lo_unbound; 1036 /* This is safe: open() is still holding a reference. */ 1037 module_put(THIS_MODULE); 1038 if (max_part > 0 && bdev) 1039 ioctl_by_bdev(bdev, BLKRRPART, 0); 1040 mutex_unlock(&lo->lo_ctl_mutex); 1041 /* 1042 * Need not hold lo_ctl_mutex to fput backing file. 1043 * Calling fput holding lo_ctl_mutex triggers a circular 1044 * lock dependency possibility warning as fput can take 1045 * bd_mutex which is usually taken before lo_ctl_mutex. 1046 */ 1047 fput(filp); 1048 return 0; 1049 } 1050 1051 static int 1052 loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 1053 { 1054 int err; 1055 struct loop_func_table *xfer; 1056 uid_t uid = current_uid(); 1057 1058 if (lo->lo_encrypt_key_size && 1059 lo->lo_key_owner != uid && 1060 !capable(CAP_SYS_ADMIN)) 1061 return -EPERM; 1062 if (lo->lo_state != Lo_bound) 1063 return -ENXIO; 1064 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) 1065 return -EINVAL; 1066 1067 err = loop_release_xfer(lo); 1068 if (err) 1069 return err; 1070 1071 if (info->lo_encrypt_type) { 1072 unsigned int type = info->lo_encrypt_type; 1073 1074 if (type >= MAX_LO_CRYPT) 1075 return -EINVAL; 1076 xfer = xfer_funcs[type]; 1077 if (xfer == NULL) 1078 return -EINVAL; 1079 } else 1080 xfer = NULL; 1081 1082 err = loop_init_xfer(lo, xfer, info); 1083 if (err) 1084 return err; 1085 1086 if (lo->lo_offset != info->lo_offset || 1087 lo->lo_sizelimit != info->lo_sizelimit) { 1088 lo->lo_offset = info->lo_offset; 1089 lo->lo_sizelimit = info->lo_sizelimit; 1090 if (figure_loop_size(lo)) 1091 return -EFBIG; 1092 } 1093 1094 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); 1095 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); 1096 lo->lo_file_name[LO_NAME_SIZE-1] = 0; 1097 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; 1098 1099 if (!xfer) 1100 xfer = &none_funcs; 1101 lo->transfer = xfer->transfer; 1102 lo->ioctl = xfer->ioctl; 1103 1104 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != 1105 (info->lo_flags & LO_FLAGS_AUTOCLEAR)) 1106 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; 1107 1108 lo->lo_encrypt_key_size = info->lo_encrypt_key_size; 1109 lo->lo_init[0] = info->lo_init[0]; 1110 lo->lo_init[1] = info->lo_init[1]; 1111 if (info->lo_encrypt_key_size) { 1112 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, 1113 info->lo_encrypt_key_size); 1114 lo->lo_key_owner = uid; 1115 } 1116 1117 return 0; 1118 } 1119 1120 static int 1121 loop_get_status(struct loop_device *lo, struct loop_info64 *info) 1122 { 1123 struct file *file = lo->lo_backing_file; 1124 struct kstat stat; 1125 int error; 1126 1127 if (lo->lo_state != Lo_bound) 1128 return -ENXIO; 1129 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat); 1130 if (error) 1131 return error; 1132 memset(info, 0, sizeof(*info)); 1133 info->lo_number = lo->lo_number; 1134 info->lo_device = huge_encode_dev(stat.dev); 1135 info->lo_inode = stat.ino; 1136 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev); 1137 info->lo_offset = lo->lo_offset; 1138 info->lo_sizelimit = lo->lo_sizelimit; 1139 info->lo_flags = lo->lo_flags; 1140 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); 1141 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE); 1142 info->lo_encrypt_type = 1143 lo->lo_encryption ? lo->lo_encryption->number : 0; 1144 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) { 1145 info->lo_encrypt_key_size = lo->lo_encrypt_key_size; 1146 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key, 1147 lo->lo_encrypt_key_size); 1148 } 1149 return 0; 1150 } 1151 1152 static void 1153 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) 1154 { 1155 memset(info64, 0, sizeof(*info64)); 1156 info64->lo_number = info->lo_number; 1157 info64->lo_device = info->lo_device; 1158 info64->lo_inode = info->lo_inode; 1159 info64->lo_rdevice = info->lo_rdevice; 1160 info64->lo_offset = info->lo_offset; 1161 info64->lo_sizelimit = 0; 1162 info64->lo_encrypt_type = info->lo_encrypt_type; 1163 info64->lo_encrypt_key_size = info->lo_encrypt_key_size; 1164 info64->lo_flags = info->lo_flags; 1165 info64->lo_init[0] = info->lo_init[0]; 1166 info64->lo_init[1] = info->lo_init[1]; 1167 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1168 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE); 1169 else 1170 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); 1171 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE); 1172 } 1173 1174 static int 1175 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) 1176 { 1177 memset(info, 0, sizeof(*info)); 1178 info->lo_number = info64->lo_number; 1179 info->lo_device = info64->lo_device; 1180 info->lo_inode = info64->lo_inode; 1181 info->lo_rdevice = info64->lo_rdevice; 1182 info->lo_offset = info64->lo_offset; 1183 info->lo_encrypt_type = info64->lo_encrypt_type; 1184 info->lo_encrypt_key_size = info64->lo_encrypt_key_size; 1185 info->lo_flags = info64->lo_flags; 1186 info->lo_init[0] = info64->lo_init[0]; 1187 info->lo_init[1] = info64->lo_init[1]; 1188 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1189 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1190 else 1191 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); 1192 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1193 1194 /* error in case values were truncated */ 1195 if (info->lo_device != info64->lo_device || 1196 info->lo_rdevice != info64->lo_rdevice || 1197 info->lo_inode != info64->lo_inode || 1198 info->lo_offset != info64->lo_offset) 1199 return -EOVERFLOW; 1200 1201 return 0; 1202 } 1203 1204 static int 1205 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) 1206 { 1207 struct loop_info info; 1208 struct loop_info64 info64; 1209 1210 if (copy_from_user(&info, arg, sizeof (struct loop_info))) 1211 return -EFAULT; 1212 loop_info64_from_old(&info, &info64); 1213 return loop_set_status(lo, &info64); 1214 } 1215 1216 static int 1217 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) 1218 { 1219 struct loop_info64 info64; 1220 1221 if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) 1222 return -EFAULT; 1223 return loop_set_status(lo, &info64); 1224 } 1225 1226 static int 1227 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { 1228 struct loop_info info; 1229 struct loop_info64 info64; 1230 int err = 0; 1231 1232 if (!arg) 1233 err = -EINVAL; 1234 if (!err) 1235 err = loop_get_status(lo, &info64); 1236 if (!err) 1237 err = loop_info64_to_old(&info64, &info); 1238 if (!err && copy_to_user(arg, &info, sizeof(info))) 1239 err = -EFAULT; 1240 1241 return err; 1242 } 1243 1244 static int 1245 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { 1246 struct loop_info64 info64; 1247 int err = 0; 1248 1249 if (!arg) 1250 err = -EINVAL; 1251 if (!err) 1252 err = loop_get_status(lo, &info64); 1253 if (!err && copy_to_user(arg, &info64, sizeof(info64))) 1254 err = -EFAULT; 1255 1256 return err; 1257 } 1258 1259 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev) 1260 { 1261 int err; 1262 sector_t sec; 1263 loff_t sz; 1264 1265 err = -ENXIO; 1266 if (unlikely(lo->lo_state != Lo_bound)) 1267 goto out; 1268 err = figure_loop_size(lo); 1269 if (unlikely(err)) 1270 goto out; 1271 sec = get_capacity(lo->lo_disk); 1272 /* the width of sector_t may be narrow for bit-shift */ 1273 sz = sec; 1274 sz <<= 9; 1275 mutex_lock(&bdev->bd_mutex); 1276 bd_set_size(bdev, sz); 1277 /* let user-space know about the new size */ 1278 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 1279 mutex_unlock(&bdev->bd_mutex); 1280 1281 out: 1282 return err; 1283 } 1284 1285 static int lo_ioctl(struct block_device *bdev, fmode_t mode, 1286 unsigned int cmd, unsigned long arg) 1287 { 1288 struct loop_device *lo = bdev->bd_disk->private_data; 1289 int err; 1290 1291 mutex_lock_nested(&lo->lo_ctl_mutex, 1); 1292 switch (cmd) { 1293 case LOOP_SET_FD: 1294 err = loop_set_fd(lo, mode, bdev, arg); 1295 break; 1296 case LOOP_CHANGE_FD: 1297 err = loop_change_fd(lo, bdev, arg); 1298 break; 1299 case LOOP_CLR_FD: 1300 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */ 1301 err = loop_clr_fd(lo, bdev); 1302 if (!err) 1303 goto out_unlocked; 1304 break; 1305 case LOOP_SET_STATUS: 1306 err = loop_set_status_old(lo, (struct loop_info __user *) arg); 1307 break; 1308 case LOOP_GET_STATUS: 1309 err = loop_get_status_old(lo, (struct loop_info __user *) arg); 1310 break; 1311 case LOOP_SET_STATUS64: 1312 err = loop_set_status64(lo, (struct loop_info64 __user *) arg); 1313 break; 1314 case LOOP_GET_STATUS64: 1315 err = loop_get_status64(lo, (struct loop_info64 __user *) arg); 1316 break; 1317 case LOOP_SET_CAPACITY: 1318 err = -EPERM; 1319 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1320 err = loop_set_capacity(lo, bdev); 1321 break; 1322 default: 1323 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; 1324 } 1325 mutex_unlock(&lo->lo_ctl_mutex); 1326 1327 out_unlocked: 1328 return err; 1329 } 1330 1331 #ifdef CONFIG_COMPAT 1332 struct compat_loop_info { 1333 compat_int_t lo_number; /* ioctl r/o */ 1334 compat_dev_t lo_device; /* ioctl r/o */ 1335 compat_ulong_t lo_inode; /* ioctl r/o */ 1336 compat_dev_t lo_rdevice; /* ioctl r/o */ 1337 compat_int_t lo_offset; 1338 compat_int_t lo_encrypt_type; 1339 compat_int_t lo_encrypt_key_size; /* ioctl w/o */ 1340 compat_int_t lo_flags; /* ioctl r/o */ 1341 char lo_name[LO_NAME_SIZE]; 1342 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ 1343 compat_ulong_t lo_init[2]; 1344 char reserved[4]; 1345 }; 1346 1347 /* 1348 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info 1349 * - noinlined to reduce stack space usage in main part of driver 1350 */ 1351 static noinline int 1352 loop_info64_from_compat(const struct compat_loop_info __user *arg, 1353 struct loop_info64 *info64) 1354 { 1355 struct compat_loop_info info; 1356 1357 if (copy_from_user(&info, arg, sizeof(info))) 1358 return -EFAULT; 1359 1360 memset(info64, 0, sizeof(*info64)); 1361 info64->lo_number = info.lo_number; 1362 info64->lo_device = info.lo_device; 1363 info64->lo_inode = info.lo_inode; 1364 info64->lo_rdevice = info.lo_rdevice; 1365 info64->lo_offset = info.lo_offset; 1366 info64->lo_sizelimit = 0; 1367 info64->lo_encrypt_type = info.lo_encrypt_type; 1368 info64->lo_encrypt_key_size = info.lo_encrypt_key_size; 1369 info64->lo_flags = info.lo_flags; 1370 info64->lo_init[0] = info.lo_init[0]; 1371 info64->lo_init[1] = info.lo_init[1]; 1372 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1373 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE); 1374 else 1375 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); 1376 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE); 1377 return 0; 1378 } 1379 1380 /* 1381 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace 1382 * - noinlined to reduce stack space usage in main part of driver 1383 */ 1384 static noinline int 1385 loop_info64_to_compat(const struct loop_info64 *info64, 1386 struct compat_loop_info __user *arg) 1387 { 1388 struct compat_loop_info info; 1389 1390 memset(&info, 0, sizeof(info)); 1391 info.lo_number = info64->lo_number; 1392 info.lo_device = info64->lo_device; 1393 info.lo_inode = info64->lo_inode; 1394 info.lo_rdevice = info64->lo_rdevice; 1395 info.lo_offset = info64->lo_offset; 1396 info.lo_encrypt_type = info64->lo_encrypt_type; 1397 info.lo_encrypt_key_size = info64->lo_encrypt_key_size; 1398 info.lo_flags = info64->lo_flags; 1399 info.lo_init[0] = info64->lo_init[0]; 1400 info.lo_init[1] = info64->lo_init[1]; 1401 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1402 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1403 else 1404 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); 1405 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1406 1407 /* error in case values were truncated */ 1408 if (info.lo_device != info64->lo_device || 1409 info.lo_rdevice != info64->lo_rdevice || 1410 info.lo_inode != info64->lo_inode || 1411 info.lo_offset != info64->lo_offset || 1412 info.lo_init[0] != info64->lo_init[0] || 1413 info.lo_init[1] != info64->lo_init[1]) 1414 return -EOVERFLOW; 1415 1416 if (copy_to_user(arg, &info, sizeof(info))) 1417 return -EFAULT; 1418 return 0; 1419 } 1420 1421 static int 1422 loop_set_status_compat(struct loop_device *lo, 1423 const struct compat_loop_info __user *arg) 1424 { 1425 struct loop_info64 info64; 1426 int ret; 1427 1428 ret = loop_info64_from_compat(arg, &info64); 1429 if (ret < 0) 1430 return ret; 1431 return loop_set_status(lo, &info64); 1432 } 1433 1434 static int 1435 loop_get_status_compat(struct loop_device *lo, 1436 struct compat_loop_info __user *arg) 1437 { 1438 struct loop_info64 info64; 1439 int err = 0; 1440 1441 if (!arg) 1442 err = -EINVAL; 1443 if (!err) 1444 err = loop_get_status(lo, &info64); 1445 if (!err) 1446 err = loop_info64_to_compat(&info64, arg); 1447 return err; 1448 } 1449 1450 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 1451 unsigned int cmd, unsigned long arg) 1452 { 1453 struct loop_device *lo = bdev->bd_disk->private_data; 1454 int err; 1455 1456 switch(cmd) { 1457 case LOOP_SET_STATUS: 1458 mutex_lock(&lo->lo_ctl_mutex); 1459 err = loop_set_status_compat( 1460 lo, (const struct compat_loop_info __user *) arg); 1461 mutex_unlock(&lo->lo_ctl_mutex); 1462 break; 1463 case LOOP_GET_STATUS: 1464 mutex_lock(&lo->lo_ctl_mutex); 1465 err = loop_get_status_compat( 1466 lo, (struct compat_loop_info __user *) arg); 1467 mutex_unlock(&lo->lo_ctl_mutex); 1468 break; 1469 case LOOP_SET_CAPACITY: 1470 case LOOP_CLR_FD: 1471 case LOOP_GET_STATUS64: 1472 case LOOP_SET_STATUS64: 1473 arg = (unsigned long) compat_ptr(arg); 1474 case LOOP_SET_FD: 1475 case LOOP_CHANGE_FD: 1476 err = lo_ioctl(bdev, mode, cmd, arg); 1477 break; 1478 default: 1479 err = -ENOIOCTLCMD; 1480 break; 1481 } 1482 return err; 1483 } 1484 #endif 1485 1486 static int lo_open(struct block_device *bdev, fmode_t mode) 1487 { 1488 struct loop_device *lo = bdev->bd_disk->private_data; 1489 1490 mutex_lock(&lo->lo_ctl_mutex); 1491 lo->lo_refcnt++; 1492 mutex_unlock(&lo->lo_ctl_mutex); 1493 1494 return 0; 1495 } 1496 1497 static int lo_release(struct gendisk *disk, fmode_t mode) 1498 { 1499 struct loop_device *lo = disk->private_data; 1500 int err; 1501 1502 mutex_lock(&lo->lo_ctl_mutex); 1503 1504 if (--lo->lo_refcnt) 1505 goto out; 1506 1507 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { 1508 /* 1509 * In autoclear mode, stop the loop thread 1510 * and remove configuration after last close. 1511 */ 1512 err = loop_clr_fd(lo, NULL); 1513 if (!err) 1514 goto out_unlocked; 1515 } else { 1516 /* 1517 * Otherwise keep thread (if running) and config, 1518 * but flush possible ongoing bios in thread. 1519 */ 1520 loop_flush(lo); 1521 } 1522 1523 out: 1524 mutex_unlock(&lo->lo_ctl_mutex); 1525 out_unlocked: 1526 return 0; 1527 } 1528 1529 static const struct block_device_operations lo_fops = { 1530 .owner = THIS_MODULE, 1531 .open = lo_open, 1532 .release = lo_release, 1533 .ioctl = lo_ioctl, 1534 #ifdef CONFIG_COMPAT 1535 .compat_ioctl = lo_compat_ioctl, 1536 #endif 1537 }; 1538 1539 /* 1540 * And now the modules code and kernel interface. 1541 */ 1542 static int max_loop; 1543 module_param(max_loop, int, S_IRUGO); 1544 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); 1545 module_param(max_part, int, S_IRUGO); 1546 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); 1547 MODULE_LICENSE("GPL"); 1548 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); 1549 1550 int loop_register_transfer(struct loop_func_table *funcs) 1551 { 1552 unsigned int n = funcs->number; 1553 1554 if (n >= MAX_LO_CRYPT || xfer_funcs[n]) 1555 return -EINVAL; 1556 xfer_funcs[n] = funcs; 1557 return 0; 1558 } 1559 1560 int loop_unregister_transfer(int number) 1561 { 1562 unsigned int n = number; 1563 struct loop_device *lo; 1564 struct loop_func_table *xfer; 1565 1566 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) 1567 return -EINVAL; 1568 1569 xfer_funcs[n] = NULL; 1570 1571 list_for_each_entry(lo, &loop_devices, lo_list) { 1572 mutex_lock(&lo->lo_ctl_mutex); 1573 1574 if (lo->lo_encryption == xfer) 1575 loop_release_xfer(lo); 1576 1577 mutex_unlock(&lo->lo_ctl_mutex); 1578 } 1579 1580 return 0; 1581 } 1582 1583 EXPORT_SYMBOL(loop_register_transfer); 1584 EXPORT_SYMBOL(loop_unregister_transfer); 1585 1586 static struct loop_device *loop_alloc(int i) 1587 { 1588 struct loop_device *lo; 1589 struct gendisk *disk; 1590 1591 lo = kzalloc(sizeof(*lo), GFP_KERNEL); 1592 if (!lo) 1593 goto out; 1594 1595 lo->lo_queue = blk_alloc_queue(GFP_KERNEL); 1596 if (!lo->lo_queue) 1597 goto out_free_dev; 1598 1599 disk = lo->lo_disk = alloc_disk(1 << part_shift); 1600 if (!disk) 1601 goto out_free_queue; 1602 1603 mutex_init(&lo->lo_ctl_mutex); 1604 lo->lo_number = i; 1605 lo->lo_thread = NULL; 1606 init_waitqueue_head(&lo->lo_event); 1607 spin_lock_init(&lo->lo_lock); 1608 disk->major = LOOP_MAJOR; 1609 disk->first_minor = i << part_shift; 1610 disk->fops = &lo_fops; 1611 disk->private_data = lo; 1612 disk->queue = lo->lo_queue; 1613 sprintf(disk->disk_name, "loop%d", i); 1614 return lo; 1615 1616 out_free_queue: 1617 blk_cleanup_queue(lo->lo_queue); 1618 out_free_dev: 1619 kfree(lo); 1620 out: 1621 return NULL; 1622 } 1623 1624 static void loop_free(struct loop_device *lo) 1625 { 1626 blk_cleanup_queue(lo->lo_queue); 1627 put_disk(lo->lo_disk); 1628 list_del(&lo->lo_list); 1629 kfree(lo); 1630 } 1631 1632 static struct loop_device *loop_init_one(int i) 1633 { 1634 struct loop_device *lo; 1635 1636 list_for_each_entry(lo, &loop_devices, lo_list) { 1637 if (lo->lo_number == i) 1638 return lo; 1639 } 1640 1641 lo = loop_alloc(i); 1642 if (lo) { 1643 add_disk(lo->lo_disk); 1644 list_add_tail(&lo->lo_list, &loop_devices); 1645 } 1646 return lo; 1647 } 1648 1649 static void loop_del_one(struct loop_device *lo) 1650 { 1651 del_gendisk(lo->lo_disk); 1652 loop_free(lo); 1653 } 1654 1655 static struct kobject *loop_probe(dev_t dev, int *part, void *data) 1656 { 1657 struct loop_device *lo; 1658 struct kobject *kobj; 1659 1660 mutex_lock(&loop_devices_mutex); 1661 lo = loop_init_one(MINOR(dev) >> part_shift); 1662 kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM); 1663 mutex_unlock(&loop_devices_mutex); 1664 1665 *part = 0; 1666 return kobj; 1667 } 1668 1669 static int __init loop_init(void) 1670 { 1671 int i, nr; 1672 unsigned long range; 1673 struct loop_device *lo, *next; 1674 1675 /* 1676 * loop module now has a feature to instantiate underlying device 1677 * structure on-demand, provided that there is an access dev node. 1678 * However, this will not work well with user space tool that doesn't 1679 * know about such "feature". In order to not break any existing 1680 * tool, we do the following: 1681 * 1682 * (1) if max_loop is specified, create that many upfront, and this 1683 * also becomes a hard limit. 1684 * (2) if max_loop is not specified, create 8 loop device on module 1685 * load, user can further extend loop device by create dev node 1686 * themselves and have kernel automatically instantiate actual 1687 * device on-demand. 1688 */ 1689 1690 part_shift = 0; 1691 if (max_part > 0) { 1692 part_shift = fls(max_part); 1693 1694 /* 1695 * Adjust max_part according to part_shift as it is exported 1696 * to user space so that user can decide correct minor number 1697 * if [s]he want to create more devices. 1698 * 1699 * Note that -1 is required because partition 0 is reserved 1700 * for the whole disk. 1701 */ 1702 max_part = (1UL << part_shift) - 1; 1703 } 1704 1705 if ((1UL << part_shift) > DISK_MAX_PARTS) 1706 return -EINVAL; 1707 1708 if (max_loop > 1UL << (MINORBITS - part_shift)) 1709 return -EINVAL; 1710 1711 if (max_loop) { 1712 nr = max_loop; 1713 range = max_loop << part_shift; 1714 } else { 1715 nr = 8; 1716 range = 1UL << MINORBITS; 1717 } 1718 1719 if (register_blkdev(LOOP_MAJOR, "loop")) 1720 return -EIO; 1721 1722 for (i = 0; i < nr; i++) { 1723 lo = loop_alloc(i); 1724 if (!lo) 1725 goto Enomem; 1726 list_add_tail(&lo->lo_list, &loop_devices); 1727 } 1728 1729 /* point of no return */ 1730 1731 list_for_each_entry(lo, &loop_devices, lo_list) 1732 add_disk(lo->lo_disk); 1733 1734 blk_register_region(MKDEV(LOOP_MAJOR, 0), range, 1735 THIS_MODULE, loop_probe, NULL, NULL); 1736 1737 printk(KERN_INFO "loop: module loaded\n"); 1738 return 0; 1739 1740 Enomem: 1741 printk(KERN_INFO "loop: out of memory\n"); 1742 1743 list_for_each_entry_safe(lo, next, &loop_devices, lo_list) 1744 loop_free(lo); 1745 1746 unregister_blkdev(LOOP_MAJOR, "loop"); 1747 return -ENOMEM; 1748 } 1749 1750 static void __exit loop_exit(void) 1751 { 1752 unsigned long range; 1753 struct loop_device *lo, *next; 1754 1755 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; 1756 1757 list_for_each_entry_safe(lo, next, &loop_devices, lo_list) 1758 loop_del_one(lo); 1759 1760 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); 1761 unregister_blkdev(LOOP_MAJOR, "loop"); 1762 } 1763 1764 module_init(loop_init); 1765 module_exit(loop_exit); 1766 1767 #ifndef MODULE 1768 static int __init max_loop_setup(char *str) 1769 { 1770 max_loop = simple_strtol(str, NULL, 0); 1771 return 1; 1772 } 1773 1774 __setup("max_loop=", max_loop_setup); 1775 #endif 1776