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/compat.h> 67 #include <linux/suspend.h> 68 #include <linux/freezer.h> 69 #include <linux/mutex.h> 70 #include <linux/writeback.h> 71 #include <linux/completion.h> 72 #include <linux/highmem.h> 73 #include <linux/kthread.h> 74 #include <linux/splice.h> 75 #include <linux/sysfs.h> 76 #include <linux/miscdevice.h> 77 #include <linux/falloc.h> 78 #include <linux/uio.h> 79 #include "loop.h" 80 81 #include <asm/uaccess.h> 82 83 static DEFINE_IDR(loop_index_idr); 84 static DEFINE_MUTEX(loop_index_mutex); 85 86 static int max_part; 87 static int part_shift; 88 89 static int transfer_xor(struct loop_device *lo, int cmd, 90 struct page *raw_page, unsigned raw_off, 91 struct page *loop_page, unsigned loop_off, 92 int size, sector_t real_block) 93 { 94 char *raw_buf = kmap_atomic(raw_page) + raw_off; 95 char *loop_buf = kmap_atomic(loop_page) + loop_off; 96 char *in, *out, *key; 97 int i, keysize; 98 99 if (cmd == READ) { 100 in = raw_buf; 101 out = loop_buf; 102 } else { 103 in = loop_buf; 104 out = raw_buf; 105 } 106 107 key = lo->lo_encrypt_key; 108 keysize = lo->lo_encrypt_key_size; 109 for (i = 0; i < size; i++) 110 *out++ = *in++ ^ key[(i & 511) % keysize]; 111 112 kunmap_atomic(loop_buf); 113 kunmap_atomic(raw_buf); 114 cond_resched(); 115 return 0; 116 } 117 118 static int xor_init(struct loop_device *lo, const struct loop_info64 *info) 119 { 120 if (unlikely(info->lo_encrypt_key_size <= 0)) 121 return -EINVAL; 122 return 0; 123 } 124 125 static struct loop_func_table none_funcs = { 126 .number = LO_CRYPT_NONE, 127 }; 128 129 static struct loop_func_table xor_funcs = { 130 .number = LO_CRYPT_XOR, 131 .transfer = transfer_xor, 132 .init = xor_init 133 }; 134 135 /* xfer_funcs[0] is special - its release function is never called */ 136 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = { 137 &none_funcs, 138 &xor_funcs 139 }; 140 141 static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) 142 { 143 loff_t loopsize; 144 145 /* Compute loopsize in bytes */ 146 loopsize = i_size_read(file->f_mapping->host); 147 if (offset > 0) 148 loopsize -= offset; 149 /* offset is beyond i_size, weird but possible */ 150 if (loopsize < 0) 151 return 0; 152 153 if (sizelimit > 0 && sizelimit < loopsize) 154 loopsize = sizelimit; 155 /* 156 * Unfortunately, if we want to do I/O on the device, 157 * the number of 512-byte sectors has to fit into a sector_t. 158 */ 159 return loopsize >> 9; 160 } 161 162 static loff_t get_loop_size(struct loop_device *lo, struct file *file) 163 { 164 return get_size(lo->lo_offset, lo->lo_sizelimit, file); 165 } 166 167 static int 168 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit) 169 { 170 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); 171 sector_t x = (sector_t)size; 172 struct block_device *bdev = lo->lo_device; 173 174 if (unlikely((loff_t)x != size)) 175 return -EFBIG; 176 if (lo->lo_offset != offset) 177 lo->lo_offset = offset; 178 if (lo->lo_sizelimit != sizelimit) 179 lo->lo_sizelimit = sizelimit; 180 set_capacity(lo->lo_disk, x); 181 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9); 182 /* let user-space know about the new size */ 183 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 184 return 0; 185 } 186 187 static inline int 188 lo_do_transfer(struct loop_device *lo, int cmd, 189 struct page *rpage, unsigned roffs, 190 struct page *lpage, unsigned loffs, 191 int size, sector_t rblock) 192 { 193 int ret; 194 195 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); 196 if (likely(!ret)) 197 return 0; 198 199 printk_ratelimited(KERN_ERR 200 "loop: Transfer error at byte offset %llu, length %i.\n", 201 (unsigned long long)rblock << 9, size); 202 return ret; 203 } 204 205 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) 206 { 207 struct iov_iter i; 208 ssize_t bw; 209 210 iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len); 211 212 file_start_write(file); 213 bw = vfs_iter_write(file, &i, ppos); 214 file_end_write(file); 215 216 if (likely(bw == bvec->bv_len)) 217 return 0; 218 219 printk_ratelimited(KERN_ERR 220 "loop: Write error at byte offset %llu, length %i.\n", 221 (unsigned long long)*ppos, bvec->bv_len); 222 if (bw >= 0) 223 bw = -EIO; 224 return bw; 225 } 226 227 static int lo_write_simple(struct loop_device *lo, struct request *rq, 228 loff_t pos) 229 { 230 struct bio_vec bvec; 231 struct req_iterator iter; 232 int ret = 0; 233 234 rq_for_each_segment(bvec, rq, iter) { 235 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); 236 if (ret < 0) 237 break; 238 cond_resched(); 239 } 240 241 return ret; 242 } 243 244 /* 245 * This is the slow, transforming version that needs to double buffer the 246 * data as it cannot do the transformations in place without having direct 247 * access to the destination pages of the backing file. 248 */ 249 static int lo_write_transfer(struct loop_device *lo, struct request *rq, 250 loff_t pos) 251 { 252 struct bio_vec bvec, b; 253 struct req_iterator iter; 254 struct page *page; 255 int ret = 0; 256 257 page = alloc_page(GFP_NOIO); 258 if (unlikely(!page)) 259 return -ENOMEM; 260 261 rq_for_each_segment(bvec, rq, iter) { 262 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page, 263 bvec.bv_offset, bvec.bv_len, pos >> 9); 264 if (unlikely(ret)) 265 break; 266 267 b.bv_page = page; 268 b.bv_offset = 0; 269 b.bv_len = bvec.bv_len; 270 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos); 271 if (ret < 0) 272 break; 273 } 274 275 __free_page(page); 276 return ret; 277 } 278 279 static int lo_read_simple(struct loop_device *lo, struct request *rq, 280 loff_t pos) 281 { 282 struct bio_vec bvec; 283 struct req_iterator iter; 284 struct iov_iter i; 285 ssize_t len; 286 287 rq_for_each_segment(bvec, rq, iter) { 288 iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len); 289 len = vfs_iter_read(lo->lo_backing_file, &i, &pos); 290 if (len < 0) 291 return len; 292 293 flush_dcache_page(bvec.bv_page); 294 295 if (len != bvec.bv_len) { 296 struct bio *bio; 297 298 __rq_for_each_bio(bio, rq) 299 zero_fill_bio(bio); 300 break; 301 } 302 cond_resched(); 303 } 304 305 return 0; 306 } 307 308 static int lo_read_transfer(struct loop_device *lo, struct request *rq, 309 loff_t pos) 310 { 311 struct bio_vec bvec, b; 312 struct req_iterator iter; 313 struct iov_iter i; 314 struct page *page; 315 ssize_t len; 316 int ret = 0; 317 318 page = alloc_page(GFP_NOIO); 319 if (unlikely(!page)) 320 return -ENOMEM; 321 322 rq_for_each_segment(bvec, rq, iter) { 323 loff_t offset = pos; 324 325 b.bv_page = page; 326 b.bv_offset = 0; 327 b.bv_len = bvec.bv_len; 328 329 iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len); 330 len = vfs_iter_read(lo->lo_backing_file, &i, &pos); 331 if (len < 0) { 332 ret = len; 333 goto out_free_page; 334 } 335 336 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page, 337 bvec.bv_offset, len, offset >> 9); 338 if (ret) 339 goto out_free_page; 340 341 flush_dcache_page(bvec.bv_page); 342 343 if (len != bvec.bv_len) { 344 struct bio *bio; 345 346 __rq_for_each_bio(bio, rq) 347 zero_fill_bio(bio); 348 break; 349 } 350 } 351 352 ret = 0; 353 out_free_page: 354 __free_page(page); 355 return ret; 356 } 357 358 static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos) 359 { 360 /* 361 * We use punch hole to reclaim the free space used by the 362 * image a.k.a. discard. However we do not support discard if 363 * encryption is enabled, because it may give an attacker 364 * useful information. 365 */ 366 struct file *file = lo->lo_backing_file; 367 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE; 368 int ret; 369 370 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) { 371 ret = -EOPNOTSUPP; 372 goto out; 373 } 374 375 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); 376 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) 377 ret = -EIO; 378 out: 379 return ret; 380 } 381 382 static int lo_req_flush(struct loop_device *lo, struct request *rq) 383 { 384 struct file *file = lo->lo_backing_file; 385 int ret = vfs_fsync(file, 0); 386 if (unlikely(ret && ret != -EINVAL)) 387 ret = -EIO; 388 389 return ret; 390 } 391 392 static int do_req_filebacked(struct loop_device *lo, struct request *rq) 393 { 394 loff_t pos; 395 int ret; 396 397 pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; 398 399 if (rq->cmd_flags & REQ_WRITE) { 400 if (rq->cmd_flags & REQ_FLUSH) 401 ret = lo_req_flush(lo, rq); 402 else if (rq->cmd_flags & REQ_DISCARD) 403 ret = lo_discard(lo, rq, pos); 404 else if (lo->transfer) 405 ret = lo_write_transfer(lo, rq, pos); 406 else 407 ret = lo_write_simple(lo, rq, pos); 408 409 } else { 410 if (lo->transfer) 411 ret = lo_read_transfer(lo, rq, pos); 412 else 413 ret = lo_read_simple(lo, rq, pos); 414 } 415 416 return ret; 417 } 418 419 struct switch_request { 420 struct file *file; 421 struct completion wait; 422 }; 423 424 /* 425 * Do the actual switch; called from the BIO completion routine 426 */ 427 static void do_loop_switch(struct loop_device *lo, struct switch_request *p) 428 { 429 struct file *file = p->file; 430 struct file *old_file = lo->lo_backing_file; 431 struct address_space *mapping; 432 433 /* if no new file, only flush of queued bios requested */ 434 if (!file) 435 return; 436 437 mapping = file->f_mapping; 438 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); 439 lo->lo_backing_file = file; 440 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ? 441 mapping->host->i_bdev->bd_block_size : PAGE_SIZE; 442 lo->old_gfp_mask = mapping_gfp_mask(mapping); 443 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 444 } 445 446 /* 447 * loop_switch performs the hard work of switching a backing store. 448 * First it needs to flush existing IO, it does this by sending a magic 449 * BIO down the pipe. The completion of this BIO does the actual switch. 450 */ 451 static int loop_switch(struct loop_device *lo, struct file *file) 452 { 453 struct switch_request w; 454 455 w.file = file; 456 457 /* freeze queue and wait for completion of scheduled requests */ 458 blk_mq_freeze_queue(lo->lo_queue); 459 460 /* do the switch action */ 461 do_loop_switch(lo, &w); 462 463 /* unfreeze */ 464 blk_mq_unfreeze_queue(lo->lo_queue); 465 466 return 0; 467 } 468 469 /* 470 * Helper to flush the IOs in loop, but keeping loop thread running 471 */ 472 static int loop_flush(struct loop_device *lo) 473 { 474 return loop_switch(lo, NULL); 475 } 476 477 static void loop_reread_partitions(struct loop_device *lo, 478 struct block_device *bdev) 479 { 480 int rc; 481 482 /* 483 * bd_mutex has been held already in release path, so don't 484 * acquire it if this function is called in such case. 485 * 486 * If the reread partition isn't from release path, lo_refcnt 487 * must be at least one and it can only become zero when the 488 * current holder is released. 489 */ 490 if (!atomic_read(&lo->lo_refcnt)) 491 rc = __blkdev_reread_part(bdev); 492 else 493 rc = blkdev_reread_part(bdev); 494 if (rc) 495 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", 496 __func__, lo->lo_number, lo->lo_file_name, rc); 497 } 498 499 /* 500 * loop_change_fd switched the backing store of a loopback device to 501 * a new file. This is useful for operating system installers to free up 502 * the original file and in High Availability environments to switch to 503 * an alternative location for the content in case of server meltdown. 504 * This can only work if the loop device is used read-only, and if the 505 * new backing store is the same size and type as the old backing store. 506 */ 507 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 508 unsigned int arg) 509 { 510 struct file *file, *old_file; 511 struct inode *inode; 512 int error; 513 514 error = -ENXIO; 515 if (lo->lo_state != Lo_bound) 516 goto out; 517 518 /* the loop device has to be read-only */ 519 error = -EINVAL; 520 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) 521 goto out; 522 523 error = -EBADF; 524 file = fget(arg); 525 if (!file) 526 goto out; 527 528 inode = file->f_mapping->host; 529 old_file = lo->lo_backing_file; 530 531 error = -EINVAL; 532 533 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 534 goto out_putf; 535 536 /* size of the new backing store needs to be the same */ 537 if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) 538 goto out_putf; 539 540 /* and ... switch */ 541 error = loop_switch(lo, file); 542 if (error) 543 goto out_putf; 544 545 fput(old_file); 546 if (lo->lo_flags & LO_FLAGS_PARTSCAN) 547 loop_reread_partitions(lo, bdev); 548 return 0; 549 550 out_putf: 551 fput(file); 552 out: 553 return error; 554 } 555 556 static inline int is_loop_device(struct file *file) 557 { 558 struct inode *i = file->f_mapping->host; 559 560 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; 561 } 562 563 /* loop sysfs attributes */ 564 565 static ssize_t loop_attr_show(struct device *dev, char *page, 566 ssize_t (*callback)(struct loop_device *, char *)) 567 { 568 struct gendisk *disk = dev_to_disk(dev); 569 struct loop_device *lo = disk->private_data; 570 571 return callback(lo, page); 572 } 573 574 #define LOOP_ATTR_RO(_name) \ 575 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ 576 static ssize_t loop_attr_do_show_##_name(struct device *d, \ 577 struct device_attribute *attr, char *b) \ 578 { \ 579 return loop_attr_show(d, b, loop_attr_##_name##_show); \ 580 } \ 581 static struct device_attribute loop_attr_##_name = \ 582 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL); 583 584 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) 585 { 586 ssize_t ret; 587 char *p = NULL; 588 589 spin_lock_irq(&lo->lo_lock); 590 if (lo->lo_backing_file) 591 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); 592 spin_unlock_irq(&lo->lo_lock); 593 594 if (IS_ERR_OR_NULL(p)) 595 ret = PTR_ERR(p); 596 else { 597 ret = strlen(p); 598 memmove(buf, p, ret); 599 buf[ret++] = '\n'; 600 buf[ret] = 0; 601 } 602 603 return ret; 604 } 605 606 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) 607 { 608 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset); 609 } 610 611 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) 612 { 613 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); 614 } 615 616 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 617 { 618 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); 619 620 return sprintf(buf, "%s\n", autoclear ? "1" : "0"); 621 } 622 623 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) 624 { 625 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); 626 627 return sprintf(buf, "%s\n", partscan ? "1" : "0"); 628 } 629 630 LOOP_ATTR_RO(backing_file); 631 LOOP_ATTR_RO(offset); 632 LOOP_ATTR_RO(sizelimit); 633 LOOP_ATTR_RO(autoclear); 634 LOOP_ATTR_RO(partscan); 635 636 static struct attribute *loop_attrs[] = { 637 &loop_attr_backing_file.attr, 638 &loop_attr_offset.attr, 639 &loop_attr_sizelimit.attr, 640 &loop_attr_autoclear.attr, 641 &loop_attr_partscan.attr, 642 NULL, 643 }; 644 645 static struct attribute_group loop_attribute_group = { 646 .name = "loop", 647 .attrs= loop_attrs, 648 }; 649 650 static int loop_sysfs_init(struct loop_device *lo) 651 { 652 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, 653 &loop_attribute_group); 654 } 655 656 static void loop_sysfs_exit(struct loop_device *lo) 657 { 658 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, 659 &loop_attribute_group); 660 } 661 662 static void loop_config_discard(struct loop_device *lo) 663 { 664 struct file *file = lo->lo_backing_file; 665 struct inode *inode = file->f_mapping->host; 666 struct request_queue *q = lo->lo_queue; 667 668 /* 669 * We use punch hole to reclaim the free space used by the 670 * image a.k.a. discard. However we do not support discard if 671 * encryption is enabled, because it may give an attacker 672 * useful information. 673 */ 674 if ((!file->f_op->fallocate) || 675 lo->lo_encrypt_key_size) { 676 q->limits.discard_granularity = 0; 677 q->limits.discard_alignment = 0; 678 q->limits.max_discard_sectors = 0; 679 q->limits.discard_zeroes_data = 0; 680 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); 681 return; 682 } 683 684 q->limits.discard_granularity = inode->i_sb->s_blocksize; 685 q->limits.discard_alignment = 0; 686 q->limits.max_discard_sectors = UINT_MAX >> 9; 687 q->limits.discard_zeroes_data = 1; 688 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); 689 } 690 691 static int loop_set_fd(struct loop_device *lo, fmode_t mode, 692 struct block_device *bdev, unsigned int arg) 693 { 694 struct file *file, *f; 695 struct inode *inode; 696 struct address_space *mapping; 697 unsigned lo_blocksize; 698 int lo_flags = 0; 699 int error; 700 loff_t size; 701 702 /* This is safe, since we have a reference from open(). */ 703 __module_get(THIS_MODULE); 704 705 error = -EBADF; 706 file = fget(arg); 707 if (!file) 708 goto out; 709 710 error = -EBUSY; 711 if (lo->lo_state != Lo_unbound) 712 goto out_putf; 713 714 /* Avoid recursion */ 715 f = file; 716 while (is_loop_device(f)) { 717 struct loop_device *l; 718 719 if (f->f_mapping->host->i_bdev == bdev) 720 goto out_putf; 721 722 l = f->f_mapping->host->i_bdev->bd_disk->private_data; 723 if (l->lo_state == Lo_unbound) { 724 error = -EINVAL; 725 goto out_putf; 726 } 727 f = l->lo_backing_file; 728 } 729 730 mapping = file->f_mapping; 731 inode = mapping->host; 732 733 error = -EINVAL; 734 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 735 goto out_putf; 736 737 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || 738 !file->f_op->write_iter) 739 lo_flags |= LO_FLAGS_READ_ONLY; 740 741 lo_blocksize = S_ISBLK(inode->i_mode) ? 742 inode->i_bdev->bd_block_size : PAGE_SIZE; 743 744 error = -EFBIG; 745 size = get_loop_size(lo, file); 746 if ((loff_t)(sector_t)size != size) 747 goto out_putf; 748 error = -ENOMEM; 749 lo->wq = alloc_workqueue("kloopd%d", 750 WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16, 751 lo->lo_number); 752 if (!lo->wq) 753 goto out_putf; 754 755 error = 0; 756 757 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); 758 759 lo->lo_blocksize = lo_blocksize; 760 lo->lo_device = bdev; 761 lo->lo_flags = lo_flags; 762 lo->lo_backing_file = file; 763 lo->transfer = NULL; 764 lo->ioctl = NULL; 765 lo->lo_sizelimit = 0; 766 lo->old_gfp_mask = mapping_gfp_mask(mapping); 767 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 768 769 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) 770 blk_queue_flush(lo->lo_queue, REQ_FLUSH); 771 772 set_capacity(lo->lo_disk, size); 773 bd_set_size(bdev, size << 9); 774 loop_sysfs_init(lo); 775 /* let user-space know about the new size */ 776 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 777 778 set_blocksize(bdev, lo_blocksize); 779 780 lo->lo_state = Lo_bound; 781 if (part_shift) 782 lo->lo_flags |= LO_FLAGS_PARTSCAN; 783 if (lo->lo_flags & LO_FLAGS_PARTSCAN) 784 loop_reread_partitions(lo, bdev); 785 786 /* Grab the block_device to prevent its destruction after we 787 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). 788 */ 789 bdgrab(bdev); 790 return 0; 791 792 out_putf: 793 fput(file); 794 out: 795 /* This is safe: open() is still holding a reference. */ 796 module_put(THIS_MODULE); 797 return error; 798 } 799 800 static int 801 loop_release_xfer(struct loop_device *lo) 802 { 803 int err = 0; 804 struct loop_func_table *xfer = lo->lo_encryption; 805 806 if (xfer) { 807 if (xfer->release) 808 err = xfer->release(lo); 809 lo->transfer = NULL; 810 lo->lo_encryption = NULL; 811 module_put(xfer->owner); 812 } 813 return err; 814 } 815 816 static int 817 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 818 const struct loop_info64 *i) 819 { 820 int err = 0; 821 822 if (xfer) { 823 struct module *owner = xfer->owner; 824 825 if (!try_module_get(owner)) 826 return -EINVAL; 827 if (xfer->init) 828 err = xfer->init(lo, i); 829 if (err) 830 module_put(owner); 831 else 832 lo->lo_encryption = xfer; 833 } 834 return err; 835 } 836 837 static int loop_clr_fd(struct loop_device *lo) 838 { 839 struct file *filp = lo->lo_backing_file; 840 gfp_t gfp = lo->old_gfp_mask; 841 struct block_device *bdev = lo->lo_device; 842 843 if (lo->lo_state != Lo_bound) 844 return -ENXIO; 845 846 /* 847 * If we've explicitly asked to tear down the loop device, 848 * and it has an elevated reference count, set it for auto-teardown when 849 * the last reference goes away. This stops $!~#$@ udev from 850 * preventing teardown because it decided that it needs to run blkid on 851 * the loopback device whenever they appear. xfstests is notorious for 852 * failing tests because blkid via udev races with a losetup 853 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d 854 * command to fail with EBUSY. 855 */ 856 if (atomic_read(&lo->lo_refcnt) > 1) { 857 lo->lo_flags |= LO_FLAGS_AUTOCLEAR; 858 mutex_unlock(&lo->lo_ctl_mutex); 859 return 0; 860 } 861 862 if (filp == NULL) 863 return -EINVAL; 864 865 /* freeze request queue during the transition */ 866 blk_mq_freeze_queue(lo->lo_queue); 867 868 spin_lock_irq(&lo->lo_lock); 869 lo->lo_state = Lo_rundown; 870 lo->lo_backing_file = NULL; 871 spin_unlock_irq(&lo->lo_lock); 872 873 loop_release_xfer(lo); 874 lo->transfer = NULL; 875 lo->ioctl = NULL; 876 lo->lo_device = NULL; 877 lo->lo_encryption = NULL; 878 lo->lo_offset = 0; 879 lo->lo_sizelimit = 0; 880 lo->lo_encrypt_key_size = 0; 881 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); 882 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); 883 memset(lo->lo_file_name, 0, LO_NAME_SIZE); 884 if (bdev) { 885 bdput(bdev); 886 invalidate_bdev(bdev); 887 } 888 set_capacity(lo->lo_disk, 0); 889 loop_sysfs_exit(lo); 890 if (bdev) { 891 bd_set_size(bdev, 0); 892 /* let user-space know about this change */ 893 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 894 } 895 mapping_set_gfp_mask(filp->f_mapping, gfp); 896 lo->lo_state = Lo_unbound; 897 /* This is safe: open() is still holding a reference. */ 898 module_put(THIS_MODULE); 899 blk_mq_unfreeze_queue(lo->lo_queue); 900 901 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) 902 loop_reread_partitions(lo, bdev); 903 lo->lo_flags = 0; 904 if (!part_shift) 905 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; 906 destroy_workqueue(lo->wq); 907 lo->wq = NULL; 908 mutex_unlock(&lo->lo_ctl_mutex); 909 /* 910 * Need not hold lo_ctl_mutex to fput backing file. 911 * Calling fput holding lo_ctl_mutex triggers a circular 912 * lock dependency possibility warning as fput can take 913 * bd_mutex which is usually taken before lo_ctl_mutex. 914 */ 915 fput(filp); 916 return 0; 917 } 918 919 static int 920 loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 921 { 922 int err; 923 struct loop_func_table *xfer; 924 kuid_t uid = current_uid(); 925 926 if (lo->lo_encrypt_key_size && 927 !uid_eq(lo->lo_key_owner, uid) && 928 !capable(CAP_SYS_ADMIN)) 929 return -EPERM; 930 if (lo->lo_state != Lo_bound) 931 return -ENXIO; 932 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) 933 return -EINVAL; 934 935 err = loop_release_xfer(lo); 936 if (err) 937 return err; 938 939 if (info->lo_encrypt_type) { 940 unsigned int type = info->lo_encrypt_type; 941 942 if (type >= MAX_LO_CRYPT) 943 return -EINVAL; 944 xfer = xfer_funcs[type]; 945 if (xfer == NULL) 946 return -EINVAL; 947 } else 948 xfer = NULL; 949 950 err = loop_init_xfer(lo, xfer, info); 951 if (err) 952 return err; 953 954 if (lo->lo_offset != info->lo_offset || 955 lo->lo_sizelimit != info->lo_sizelimit) 956 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit)) 957 return -EFBIG; 958 959 loop_config_discard(lo); 960 961 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); 962 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); 963 lo->lo_file_name[LO_NAME_SIZE-1] = 0; 964 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; 965 966 if (!xfer) 967 xfer = &none_funcs; 968 lo->transfer = xfer->transfer; 969 lo->ioctl = xfer->ioctl; 970 971 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != 972 (info->lo_flags & LO_FLAGS_AUTOCLEAR)) 973 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; 974 975 if ((info->lo_flags & LO_FLAGS_PARTSCAN) && 976 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { 977 lo->lo_flags |= LO_FLAGS_PARTSCAN; 978 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; 979 loop_reread_partitions(lo, lo->lo_device); 980 } 981 982 lo->lo_encrypt_key_size = info->lo_encrypt_key_size; 983 lo->lo_init[0] = info->lo_init[0]; 984 lo->lo_init[1] = info->lo_init[1]; 985 if (info->lo_encrypt_key_size) { 986 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, 987 info->lo_encrypt_key_size); 988 lo->lo_key_owner = uid; 989 } 990 991 return 0; 992 } 993 994 static int 995 loop_get_status(struct loop_device *lo, struct loop_info64 *info) 996 { 997 struct file *file = lo->lo_backing_file; 998 struct kstat stat; 999 int error; 1000 1001 if (lo->lo_state != Lo_bound) 1002 return -ENXIO; 1003 error = vfs_getattr(&file->f_path, &stat); 1004 if (error) 1005 return error; 1006 memset(info, 0, sizeof(*info)); 1007 info->lo_number = lo->lo_number; 1008 info->lo_device = huge_encode_dev(stat.dev); 1009 info->lo_inode = stat.ino; 1010 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev); 1011 info->lo_offset = lo->lo_offset; 1012 info->lo_sizelimit = lo->lo_sizelimit; 1013 info->lo_flags = lo->lo_flags; 1014 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); 1015 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE); 1016 info->lo_encrypt_type = 1017 lo->lo_encryption ? lo->lo_encryption->number : 0; 1018 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) { 1019 info->lo_encrypt_key_size = lo->lo_encrypt_key_size; 1020 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key, 1021 lo->lo_encrypt_key_size); 1022 } 1023 return 0; 1024 } 1025 1026 static void 1027 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) 1028 { 1029 memset(info64, 0, sizeof(*info64)); 1030 info64->lo_number = info->lo_number; 1031 info64->lo_device = info->lo_device; 1032 info64->lo_inode = info->lo_inode; 1033 info64->lo_rdevice = info->lo_rdevice; 1034 info64->lo_offset = info->lo_offset; 1035 info64->lo_sizelimit = 0; 1036 info64->lo_encrypt_type = info->lo_encrypt_type; 1037 info64->lo_encrypt_key_size = info->lo_encrypt_key_size; 1038 info64->lo_flags = info->lo_flags; 1039 info64->lo_init[0] = info->lo_init[0]; 1040 info64->lo_init[1] = info->lo_init[1]; 1041 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1042 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE); 1043 else 1044 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); 1045 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE); 1046 } 1047 1048 static int 1049 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) 1050 { 1051 memset(info, 0, sizeof(*info)); 1052 info->lo_number = info64->lo_number; 1053 info->lo_device = info64->lo_device; 1054 info->lo_inode = info64->lo_inode; 1055 info->lo_rdevice = info64->lo_rdevice; 1056 info->lo_offset = info64->lo_offset; 1057 info->lo_encrypt_type = info64->lo_encrypt_type; 1058 info->lo_encrypt_key_size = info64->lo_encrypt_key_size; 1059 info->lo_flags = info64->lo_flags; 1060 info->lo_init[0] = info64->lo_init[0]; 1061 info->lo_init[1] = info64->lo_init[1]; 1062 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1063 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1064 else 1065 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); 1066 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1067 1068 /* error in case values were truncated */ 1069 if (info->lo_device != info64->lo_device || 1070 info->lo_rdevice != info64->lo_rdevice || 1071 info->lo_inode != info64->lo_inode || 1072 info->lo_offset != info64->lo_offset) 1073 return -EOVERFLOW; 1074 1075 return 0; 1076 } 1077 1078 static int 1079 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) 1080 { 1081 struct loop_info info; 1082 struct loop_info64 info64; 1083 1084 if (copy_from_user(&info, arg, sizeof (struct loop_info))) 1085 return -EFAULT; 1086 loop_info64_from_old(&info, &info64); 1087 return loop_set_status(lo, &info64); 1088 } 1089 1090 static int 1091 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) 1092 { 1093 struct loop_info64 info64; 1094 1095 if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) 1096 return -EFAULT; 1097 return loop_set_status(lo, &info64); 1098 } 1099 1100 static int 1101 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { 1102 struct loop_info info; 1103 struct loop_info64 info64; 1104 int err = 0; 1105 1106 if (!arg) 1107 err = -EINVAL; 1108 if (!err) 1109 err = loop_get_status(lo, &info64); 1110 if (!err) 1111 err = loop_info64_to_old(&info64, &info); 1112 if (!err && copy_to_user(arg, &info, sizeof(info))) 1113 err = -EFAULT; 1114 1115 return err; 1116 } 1117 1118 static int 1119 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { 1120 struct loop_info64 info64; 1121 int err = 0; 1122 1123 if (!arg) 1124 err = -EINVAL; 1125 if (!err) 1126 err = loop_get_status(lo, &info64); 1127 if (!err && copy_to_user(arg, &info64, sizeof(info64))) 1128 err = -EFAULT; 1129 1130 return err; 1131 } 1132 1133 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev) 1134 { 1135 if (unlikely(lo->lo_state != Lo_bound)) 1136 return -ENXIO; 1137 1138 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit); 1139 } 1140 1141 static int lo_ioctl(struct block_device *bdev, fmode_t mode, 1142 unsigned int cmd, unsigned long arg) 1143 { 1144 struct loop_device *lo = bdev->bd_disk->private_data; 1145 int err; 1146 1147 mutex_lock_nested(&lo->lo_ctl_mutex, 1); 1148 switch (cmd) { 1149 case LOOP_SET_FD: 1150 err = loop_set_fd(lo, mode, bdev, arg); 1151 break; 1152 case LOOP_CHANGE_FD: 1153 err = loop_change_fd(lo, bdev, arg); 1154 break; 1155 case LOOP_CLR_FD: 1156 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */ 1157 err = loop_clr_fd(lo); 1158 if (!err) 1159 goto out_unlocked; 1160 break; 1161 case LOOP_SET_STATUS: 1162 err = -EPERM; 1163 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1164 err = loop_set_status_old(lo, 1165 (struct loop_info __user *)arg); 1166 break; 1167 case LOOP_GET_STATUS: 1168 err = loop_get_status_old(lo, (struct loop_info __user *) arg); 1169 break; 1170 case LOOP_SET_STATUS64: 1171 err = -EPERM; 1172 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1173 err = loop_set_status64(lo, 1174 (struct loop_info64 __user *) arg); 1175 break; 1176 case LOOP_GET_STATUS64: 1177 err = loop_get_status64(lo, (struct loop_info64 __user *) arg); 1178 break; 1179 case LOOP_SET_CAPACITY: 1180 err = -EPERM; 1181 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1182 err = loop_set_capacity(lo, bdev); 1183 break; 1184 default: 1185 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; 1186 } 1187 mutex_unlock(&lo->lo_ctl_mutex); 1188 1189 out_unlocked: 1190 return err; 1191 } 1192 1193 #ifdef CONFIG_COMPAT 1194 struct compat_loop_info { 1195 compat_int_t lo_number; /* ioctl r/o */ 1196 compat_dev_t lo_device; /* ioctl r/o */ 1197 compat_ulong_t lo_inode; /* ioctl r/o */ 1198 compat_dev_t lo_rdevice; /* ioctl r/o */ 1199 compat_int_t lo_offset; 1200 compat_int_t lo_encrypt_type; 1201 compat_int_t lo_encrypt_key_size; /* ioctl w/o */ 1202 compat_int_t lo_flags; /* ioctl r/o */ 1203 char lo_name[LO_NAME_SIZE]; 1204 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ 1205 compat_ulong_t lo_init[2]; 1206 char reserved[4]; 1207 }; 1208 1209 /* 1210 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info 1211 * - noinlined to reduce stack space usage in main part of driver 1212 */ 1213 static noinline int 1214 loop_info64_from_compat(const struct compat_loop_info __user *arg, 1215 struct loop_info64 *info64) 1216 { 1217 struct compat_loop_info info; 1218 1219 if (copy_from_user(&info, arg, sizeof(info))) 1220 return -EFAULT; 1221 1222 memset(info64, 0, sizeof(*info64)); 1223 info64->lo_number = info.lo_number; 1224 info64->lo_device = info.lo_device; 1225 info64->lo_inode = info.lo_inode; 1226 info64->lo_rdevice = info.lo_rdevice; 1227 info64->lo_offset = info.lo_offset; 1228 info64->lo_sizelimit = 0; 1229 info64->lo_encrypt_type = info.lo_encrypt_type; 1230 info64->lo_encrypt_key_size = info.lo_encrypt_key_size; 1231 info64->lo_flags = info.lo_flags; 1232 info64->lo_init[0] = info.lo_init[0]; 1233 info64->lo_init[1] = info.lo_init[1]; 1234 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1235 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE); 1236 else 1237 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); 1238 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE); 1239 return 0; 1240 } 1241 1242 /* 1243 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace 1244 * - noinlined to reduce stack space usage in main part of driver 1245 */ 1246 static noinline int 1247 loop_info64_to_compat(const struct loop_info64 *info64, 1248 struct compat_loop_info __user *arg) 1249 { 1250 struct compat_loop_info info; 1251 1252 memset(&info, 0, sizeof(info)); 1253 info.lo_number = info64->lo_number; 1254 info.lo_device = info64->lo_device; 1255 info.lo_inode = info64->lo_inode; 1256 info.lo_rdevice = info64->lo_rdevice; 1257 info.lo_offset = info64->lo_offset; 1258 info.lo_encrypt_type = info64->lo_encrypt_type; 1259 info.lo_encrypt_key_size = info64->lo_encrypt_key_size; 1260 info.lo_flags = info64->lo_flags; 1261 info.lo_init[0] = info64->lo_init[0]; 1262 info.lo_init[1] = info64->lo_init[1]; 1263 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1264 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1265 else 1266 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); 1267 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1268 1269 /* error in case values were truncated */ 1270 if (info.lo_device != info64->lo_device || 1271 info.lo_rdevice != info64->lo_rdevice || 1272 info.lo_inode != info64->lo_inode || 1273 info.lo_offset != info64->lo_offset || 1274 info.lo_init[0] != info64->lo_init[0] || 1275 info.lo_init[1] != info64->lo_init[1]) 1276 return -EOVERFLOW; 1277 1278 if (copy_to_user(arg, &info, sizeof(info))) 1279 return -EFAULT; 1280 return 0; 1281 } 1282 1283 static int 1284 loop_set_status_compat(struct loop_device *lo, 1285 const struct compat_loop_info __user *arg) 1286 { 1287 struct loop_info64 info64; 1288 int ret; 1289 1290 ret = loop_info64_from_compat(arg, &info64); 1291 if (ret < 0) 1292 return ret; 1293 return loop_set_status(lo, &info64); 1294 } 1295 1296 static int 1297 loop_get_status_compat(struct loop_device *lo, 1298 struct compat_loop_info __user *arg) 1299 { 1300 struct loop_info64 info64; 1301 int err = 0; 1302 1303 if (!arg) 1304 err = -EINVAL; 1305 if (!err) 1306 err = loop_get_status(lo, &info64); 1307 if (!err) 1308 err = loop_info64_to_compat(&info64, arg); 1309 return err; 1310 } 1311 1312 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 1313 unsigned int cmd, unsigned long arg) 1314 { 1315 struct loop_device *lo = bdev->bd_disk->private_data; 1316 int err; 1317 1318 switch(cmd) { 1319 case LOOP_SET_STATUS: 1320 mutex_lock(&lo->lo_ctl_mutex); 1321 err = loop_set_status_compat( 1322 lo, (const struct compat_loop_info __user *) arg); 1323 mutex_unlock(&lo->lo_ctl_mutex); 1324 break; 1325 case LOOP_GET_STATUS: 1326 mutex_lock(&lo->lo_ctl_mutex); 1327 err = loop_get_status_compat( 1328 lo, (struct compat_loop_info __user *) arg); 1329 mutex_unlock(&lo->lo_ctl_mutex); 1330 break; 1331 case LOOP_SET_CAPACITY: 1332 case LOOP_CLR_FD: 1333 case LOOP_GET_STATUS64: 1334 case LOOP_SET_STATUS64: 1335 arg = (unsigned long) compat_ptr(arg); 1336 case LOOP_SET_FD: 1337 case LOOP_CHANGE_FD: 1338 err = lo_ioctl(bdev, mode, cmd, arg); 1339 break; 1340 default: 1341 err = -ENOIOCTLCMD; 1342 break; 1343 } 1344 return err; 1345 } 1346 #endif 1347 1348 static int lo_open(struct block_device *bdev, fmode_t mode) 1349 { 1350 struct loop_device *lo; 1351 int err = 0; 1352 1353 mutex_lock(&loop_index_mutex); 1354 lo = bdev->bd_disk->private_data; 1355 if (!lo) { 1356 err = -ENXIO; 1357 goto out; 1358 } 1359 1360 atomic_inc(&lo->lo_refcnt); 1361 out: 1362 mutex_unlock(&loop_index_mutex); 1363 return err; 1364 } 1365 1366 static void lo_release(struct gendisk *disk, fmode_t mode) 1367 { 1368 struct loop_device *lo = disk->private_data; 1369 int err; 1370 1371 if (atomic_dec_return(&lo->lo_refcnt)) 1372 return; 1373 1374 mutex_lock(&lo->lo_ctl_mutex); 1375 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { 1376 /* 1377 * In autoclear mode, stop the loop thread 1378 * and remove configuration after last close. 1379 */ 1380 err = loop_clr_fd(lo); 1381 if (!err) 1382 return; 1383 } else { 1384 /* 1385 * Otherwise keep thread (if running) and config, 1386 * but flush possible ongoing bios in thread. 1387 */ 1388 loop_flush(lo); 1389 } 1390 1391 mutex_unlock(&lo->lo_ctl_mutex); 1392 } 1393 1394 static const struct block_device_operations lo_fops = { 1395 .owner = THIS_MODULE, 1396 .open = lo_open, 1397 .release = lo_release, 1398 .ioctl = lo_ioctl, 1399 #ifdef CONFIG_COMPAT 1400 .compat_ioctl = lo_compat_ioctl, 1401 #endif 1402 }; 1403 1404 /* 1405 * And now the modules code and kernel interface. 1406 */ 1407 static int max_loop; 1408 module_param(max_loop, int, S_IRUGO); 1409 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); 1410 module_param(max_part, int, S_IRUGO); 1411 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); 1412 MODULE_LICENSE("GPL"); 1413 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); 1414 1415 int loop_register_transfer(struct loop_func_table *funcs) 1416 { 1417 unsigned int n = funcs->number; 1418 1419 if (n >= MAX_LO_CRYPT || xfer_funcs[n]) 1420 return -EINVAL; 1421 xfer_funcs[n] = funcs; 1422 return 0; 1423 } 1424 1425 static int unregister_transfer_cb(int id, void *ptr, void *data) 1426 { 1427 struct loop_device *lo = ptr; 1428 struct loop_func_table *xfer = data; 1429 1430 mutex_lock(&lo->lo_ctl_mutex); 1431 if (lo->lo_encryption == xfer) 1432 loop_release_xfer(lo); 1433 mutex_unlock(&lo->lo_ctl_mutex); 1434 return 0; 1435 } 1436 1437 int loop_unregister_transfer(int number) 1438 { 1439 unsigned int n = number; 1440 struct loop_func_table *xfer; 1441 1442 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) 1443 return -EINVAL; 1444 1445 xfer_funcs[n] = NULL; 1446 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer); 1447 return 0; 1448 } 1449 1450 EXPORT_SYMBOL(loop_register_transfer); 1451 EXPORT_SYMBOL(loop_unregister_transfer); 1452 1453 static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, 1454 const struct blk_mq_queue_data *bd) 1455 { 1456 struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); 1457 struct loop_device *lo = cmd->rq->q->queuedata; 1458 1459 blk_mq_start_request(bd->rq); 1460 1461 if (lo->lo_state != Lo_bound) 1462 return -EIO; 1463 1464 if (cmd->rq->cmd_flags & REQ_WRITE) { 1465 struct loop_device *lo = cmd->rq->q->queuedata; 1466 bool need_sched = true; 1467 1468 spin_lock_irq(&lo->lo_lock); 1469 if (lo->write_started) 1470 need_sched = false; 1471 else 1472 lo->write_started = true; 1473 list_add_tail(&cmd->list, &lo->write_cmd_head); 1474 spin_unlock_irq(&lo->lo_lock); 1475 1476 if (need_sched) 1477 queue_work(lo->wq, &lo->write_work); 1478 } else { 1479 queue_work(lo->wq, &cmd->read_work); 1480 } 1481 1482 return BLK_MQ_RQ_QUEUE_OK; 1483 } 1484 1485 static void loop_handle_cmd(struct loop_cmd *cmd) 1486 { 1487 const bool write = cmd->rq->cmd_flags & REQ_WRITE; 1488 struct loop_device *lo = cmd->rq->q->queuedata; 1489 int ret = -EIO; 1490 1491 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) 1492 goto failed; 1493 1494 ret = do_req_filebacked(lo, cmd->rq); 1495 1496 failed: 1497 if (ret) 1498 cmd->rq->errors = -EIO; 1499 blk_mq_complete_request(cmd->rq); 1500 } 1501 1502 static void loop_queue_write_work(struct work_struct *work) 1503 { 1504 struct loop_device *lo = 1505 container_of(work, struct loop_device, write_work); 1506 LIST_HEAD(cmd_list); 1507 1508 spin_lock_irq(&lo->lo_lock); 1509 repeat: 1510 list_splice_init(&lo->write_cmd_head, &cmd_list); 1511 spin_unlock_irq(&lo->lo_lock); 1512 1513 while (!list_empty(&cmd_list)) { 1514 struct loop_cmd *cmd = list_first_entry(&cmd_list, 1515 struct loop_cmd, list); 1516 list_del_init(&cmd->list); 1517 loop_handle_cmd(cmd); 1518 } 1519 1520 spin_lock_irq(&lo->lo_lock); 1521 if (!list_empty(&lo->write_cmd_head)) 1522 goto repeat; 1523 lo->write_started = false; 1524 spin_unlock_irq(&lo->lo_lock); 1525 } 1526 1527 static void loop_queue_read_work(struct work_struct *work) 1528 { 1529 struct loop_cmd *cmd = 1530 container_of(work, struct loop_cmd, read_work); 1531 1532 loop_handle_cmd(cmd); 1533 } 1534 1535 static int loop_init_request(void *data, struct request *rq, 1536 unsigned int hctx_idx, unsigned int request_idx, 1537 unsigned int numa_node) 1538 { 1539 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 1540 1541 cmd->rq = rq; 1542 INIT_WORK(&cmd->read_work, loop_queue_read_work); 1543 1544 return 0; 1545 } 1546 1547 static struct blk_mq_ops loop_mq_ops = { 1548 .queue_rq = loop_queue_rq, 1549 .map_queue = blk_mq_map_queue, 1550 .init_request = loop_init_request, 1551 }; 1552 1553 static int loop_add(struct loop_device **l, int i) 1554 { 1555 struct loop_device *lo; 1556 struct gendisk *disk; 1557 int err; 1558 1559 err = -ENOMEM; 1560 lo = kzalloc(sizeof(*lo), GFP_KERNEL); 1561 if (!lo) 1562 goto out; 1563 1564 lo->lo_state = Lo_unbound; 1565 1566 /* allocate id, if @id >= 0, we're requesting that specific id */ 1567 if (i >= 0) { 1568 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); 1569 if (err == -ENOSPC) 1570 err = -EEXIST; 1571 } else { 1572 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); 1573 } 1574 if (err < 0) 1575 goto out_free_dev; 1576 i = err; 1577 1578 err = -ENOMEM; 1579 lo->tag_set.ops = &loop_mq_ops; 1580 lo->tag_set.nr_hw_queues = 1; 1581 lo->tag_set.queue_depth = 128; 1582 lo->tag_set.numa_node = NUMA_NO_NODE; 1583 lo->tag_set.cmd_size = sizeof(struct loop_cmd); 1584 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 1585 lo->tag_set.driver_data = lo; 1586 1587 err = blk_mq_alloc_tag_set(&lo->tag_set); 1588 if (err) 1589 goto out_free_idr; 1590 1591 lo->lo_queue = blk_mq_init_queue(&lo->tag_set); 1592 if (IS_ERR_OR_NULL(lo->lo_queue)) { 1593 err = PTR_ERR(lo->lo_queue); 1594 goto out_cleanup_tags; 1595 } 1596 lo->lo_queue->queuedata = lo; 1597 1598 INIT_LIST_HEAD(&lo->write_cmd_head); 1599 INIT_WORK(&lo->write_work, loop_queue_write_work); 1600 1601 disk = lo->lo_disk = alloc_disk(1 << part_shift); 1602 if (!disk) 1603 goto out_free_queue; 1604 1605 /* 1606 * Disable partition scanning by default. The in-kernel partition 1607 * scanning can be requested individually per-device during its 1608 * setup. Userspace can always add and remove partitions from all 1609 * devices. The needed partition minors are allocated from the 1610 * extended minor space, the main loop device numbers will continue 1611 * to match the loop minors, regardless of the number of partitions 1612 * used. 1613 * 1614 * If max_part is given, partition scanning is globally enabled for 1615 * all loop devices. The minors for the main loop devices will be 1616 * multiples of max_part. 1617 * 1618 * Note: Global-for-all-devices, set-only-at-init, read-only module 1619 * parameteters like 'max_loop' and 'max_part' make things needlessly 1620 * complicated, are too static, inflexible and may surprise 1621 * userspace tools. Parameters like this in general should be avoided. 1622 */ 1623 if (!part_shift) 1624 disk->flags |= GENHD_FL_NO_PART_SCAN; 1625 disk->flags |= GENHD_FL_EXT_DEVT; 1626 mutex_init(&lo->lo_ctl_mutex); 1627 atomic_set(&lo->lo_refcnt, 0); 1628 lo->lo_number = i; 1629 spin_lock_init(&lo->lo_lock); 1630 disk->major = LOOP_MAJOR; 1631 disk->first_minor = i << part_shift; 1632 disk->fops = &lo_fops; 1633 disk->private_data = lo; 1634 disk->queue = lo->lo_queue; 1635 sprintf(disk->disk_name, "loop%d", i); 1636 add_disk(disk); 1637 *l = lo; 1638 return lo->lo_number; 1639 1640 out_free_queue: 1641 blk_cleanup_queue(lo->lo_queue); 1642 out_cleanup_tags: 1643 blk_mq_free_tag_set(&lo->tag_set); 1644 out_free_idr: 1645 idr_remove(&loop_index_idr, i); 1646 out_free_dev: 1647 kfree(lo); 1648 out: 1649 return err; 1650 } 1651 1652 static void loop_remove(struct loop_device *lo) 1653 { 1654 blk_cleanup_queue(lo->lo_queue); 1655 del_gendisk(lo->lo_disk); 1656 blk_mq_free_tag_set(&lo->tag_set); 1657 put_disk(lo->lo_disk); 1658 kfree(lo); 1659 } 1660 1661 static int find_free_cb(int id, void *ptr, void *data) 1662 { 1663 struct loop_device *lo = ptr; 1664 struct loop_device **l = data; 1665 1666 if (lo->lo_state == Lo_unbound) { 1667 *l = lo; 1668 return 1; 1669 } 1670 return 0; 1671 } 1672 1673 static int loop_lookup(struct loop_device **l, int i) 1674 { 1675 struct loop_device *lo; 1676 int ret = -ENODEV; 1677 1678 if (i < 0) { 1679 int err; 1680 1681 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo); 1682 if (err == 1) { 1683 *l = lo; 1684 ret = lo->lo_number; 1685 } 1686 goto out; 1687 } 1688 1689 /* lookup and return a specific i */ 1690 lo = idr_find(&loop_index_idr, i); 1691 if (lo) { 1692 *l = lo; 1693 ret = lo->lo_number; 1694 } 1695 out: 1696 return ret; 1697 } 1698 1699 static struct kobject *loop_probe(dev_t dev, int *part, void *data) 1700 { 1701 struct loop_device *lo; 1702 struct kobject *kobj; 1703 int err; 1704 1705 mutex_lock(&loop_index_mutex); 1706 err = loop_lookup(&lo, MINOR(dev) >> part_shift); 1707 if (err < 0) 1708 err = loop_add(&lo, MINOR(dev) >> part_shift); 1709 if (err < 0) 1710 kobj = NULL; 1711 else 1712 kobj = get_disk(lo->lo_disk); 1713 mutex_unlock(&loop_index_mutex); 1714 1715 *part = 0; 1716 return kobj; 1717 } 1718 1719 static long loop_control_ioctl(struct file *file, unsigned int cmd, 1720 unsigned long parm) 1721 { 1722 struct loop_device *lo; 1723 int ret = -ENOSYS; 1724 1725 mutex_lock(&loop_index_mutex); 1726 switch (cmd) { 1727 case LOOP_CTL_ADD: 1728 ret = loop_lookup(&lo, parm); 1729 if (ret >= 0) { 1730 ret = -EEXIST; 1731 break; 1732 } 1733 ret = loop_add(&lo, parm); 1734 break; 1735 case LOOP_CTL_REMOVE: 1736 ret = loop_lookup(&lo, parm); 1737 if (ret < 0) 1738 break; 1739 mutex_lock(&lo->lo_ctl_mutex); 1740 if (lo->lo_state != Lo_unbound) { 1741 ret = -EBUSY; 1742 mutex_unlock(&lo->lo_ctl_mutex); 1743 break; 1744 } 1745 if (atomic_read(&lo->lo_refcnt) > 0) { 1746 ret = -EBUSY; 1747 mutex_unlock(&lo->lo_ctl_mutex); 1748 break; 1749 } 1750 lo->lo_disk->private_data = NULL; 1751 mutex_unlock(&lo->lo_ctl_mutex); 1752 idr_remove(&loop_index_idr, lo->lo_number); 1753 loop_remove(lo); 1754 break; 1755 case LOOP_CTL_GET_FREE: 1756 ret = loop_lookup(&lo, -1); 1757 if (ret >= 0) 1758 break; 1759 ret = loop_add(&lo, -1); 1760 } 1761 mutex_unlock(&loop_index_mutex); 1762 1763 return ret; 1764 } 1765 1766 static const struct file_operations loop_ctl_fops = { 1767 .open = nonseekable_open, 1768 .unlocked_ioctl = loop_control_ioctl, 1769 .compat_ioctl = loop_control_ioctl, 1770 .owner = THIS_MODULE, 1771 .llseek = noop_llseek, 1772 }; 1773 1774 static struct miscdevice loop_misc = { 1775 .minor = LOOP_CTRL_MINOR, 1776 .name = "loop-control", 1777 .fops = &loop_ctl_fops, 1778 }; 1779 1780 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); 1781 MODULE_ALIAS("devname:loop-control"); 1782 1783 static int __init loop_init(void) 1784 { 1785 int i, nr; 1786 unsigned long range; 1787 struct loop_device *lo; 1788 int err; 1789 1790 err = misc_register(&loop_misc); 1791 if (err < 0) 1792 return err; 1793 1794 part_shift = 0; 1795 if (max_part > 0) { 1796 part_shift = fls(max_part); 1797 1798 /* 1799 * Adjust max_part according to part_shift as it is exported 1800 * to user space so that user can decide correct minor number 1801 * if [s]he want to create more devices. 1802 * 1803 * Note that -1 is required because partition 0 is reserved 1804 * for the whole disk. 1805 */ 1806 max_part = (1UL << part_shift) - 1; 1807 } 1808 1809 if ((1UL << part_shift) > DISK_MAX_PARTS) { 1810 err = -EINVAL; 1811 goto misc_out; 1812 } 1813 1814 if (max_loop > 1UL << (MINORBITS - part_shift)) { 1815 err = -EINVAL; 1816 goto misc_out; 1817 } 1818 1819 /* 1820 * If max_loop is specified, create that many devices upfront. 1821 * This also becomes a hard limit. If max_loop is not specified, 1822 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module 1823 * init time. Loop devices can be requested on-demand with the 1824 * /dev/loop-control interface, or be instantiated by accessing 1825 * a 'dead' device node. 1826 */ 1827 if (max_loop) { 1828 nr = max_loop; 1829 range = max_loop << part_shift; 1830 } else { 1831 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; 1832 range = 1UL << MINORBITS; 1833 } 1834 1835 if (register_blkdev(LOOP_MAJOR, "loop")) { 1836 err = -EIO; 1837 goto misc_out; 1838 } 1839 1840 blk_register_region(MKDEV(LOOP_MAJOR, 0), range, 1841 THIS_MODULE, loop_probe, NULL, NULL); 1842 1843 /* pre-create number of devices given by config or max_loop */ 1844 mutex_lock(&loop_index_mutex); 1845 for (i = 0; i < nr; i++) 1846 loop_add(&lo, i); 1847 mutex_unlock(&loop_index_mutex); 1848 1849 printk(KERN_INFO "loop: module loaded\n"); 1850 return 0; 1851 1852 misc_out: 1853 misc_deregister(&loop_misc); 1854 return err; 1855 } 1856 1857 static int loop_exit_cb(int id, void *ptr, void *data) 1858 { 1859 struct loop_device *lo = ptr; 1860 1861 loop_remove(lo); 1862 return 0; 1863 } 1864 1865 static void __exit loop_exit(void) 1866 { 1867 unsigned long range; 1868 1869 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; 1870 1871 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); 1872 idr_destroy(&loop_index_idr); 1873 1874 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); 1875 unregister_blkdev(LOOP_MAJOR, "loop"); 1876 1877 misc_deregister(&loop_misc); 1878 } 1879 1880 module_init(loop_init); 1881 module_exit(loop_exit); 1882 1883 #ifndef MODULE 1884 static int __init max_loop_setup(char *str) 1885 { 1886 max_loop = simple_strtol(str, NULL, 0); 1887 return 1; 1888 } 1889 1890 __setup("max_loop=", max_loop_setup); 1891 #endif 1892