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 <linux/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 void __loop_update_dio(struct loop_device *lo, bool dio) 168 { 169 struct file *file = lo->lo_backing_file; 170 struct address_space *mapping = file->f_mapping; 171 struct inode *inode = mapping->host; 172 unsigned short sb_bsize = 0; 173 unsigned dio_align = 0; 174 bool use_dio; 175 176 if (inode->i_sb->s_bdev) { 177 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); 178 dio_align = sb_bsize - 1; 179 } 180 181 /* 182 * We support direct I/O only if lo_offset is aligned with the 183 * logical I/O size of backing device, and the logical block 184 * size of loop is bigger than the backing device's and the loop 185 * needn't transform transfer. 186 * 187 * TODO: the above condition may be loosed in the future, and 188 * direct I/O may be switched runtime at that time because most 189 * of requests in sane applications should be PAGE_SIZE aligned 190 */ 191 if (dio) { 192 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && 193 !(lo->lo_offset & dio_align) && 194 mapping->a_ops->direct_IO && 195 !lo->transfer) 196 use_dio = true; 197 else 198 use_dio = false; 199 } else { 200 use_dio = false; 201 } 202 203 if (lo->use_dio == use_dio) 204 return; 205 206 /* flush dirty pages before changing direct IO */ 207 vfs_fsync(file, 0); 208 209 /* 210 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with 211 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup 212 * will get updated by ioctl(LOOP_GET_STATUS) 213 */ 214 blk_mq_freeze_queue(lo->lo_queue); 215 lo->use_dio = use_dio; 216 if (use_dio) 217 lo->lo_flags |= LO_FLAGS_DIRECT_IO; 218 else 219 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; 220 blk_mq_unfreeze_queue(lo->lo_queue); 221 } 222 223 static int 224 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit, 225 loff_t logical_blocksize) 226 { 227 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file); 228 sector_t x = (sector_t)size; 229 struct block_device *bdev = lo->lo_device; 230 231 if (unlikely((loff_t)x != size)) 232 return -EFBIG; 233 if (lo->lo_offset != offset) 234 lo->lo_offset = offset; 235 if (lo->lo_sizelimit != sizelimit) 236 lo->lo_sizelimit = sizelimit; 237 if (lo->lo_flags & LO_FLAGS_BLOCKSIZE) { 238 lo->lo_logical_blocksize = logical_blocksize; 239 blk_queue_physical_block_size(lo->lo_queue, lo->lo_blocksize); 240 blk_queue_logical_block_size(lo->lo_queue, 241 lo->lo_logical_blocksize); 242 } 243 set_capacity(lo->lo_disk, x); 244 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9); 245 /* let user-space know about the new size */ 246 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 247 return 0; 248 } 249 250 static inline int 251 lo_do_transfer(struct loop_device *lo, int cmd, 252 struct page *rpage, unsigned roffs, 253 struct page *lpage, unsigned loffs, 254 int size, sector_t rblock) 255 { 256 int ret; 257 258 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); 259 if (likely(!ret)) 260 return 0; 261 262 printk_ratelimited(KERN_ERR 263 "loop: Transfer error at byte offset %llu, length %i.\n", 264 (unsigned long long)rblock << 9, size); 265 return ret; 266 } 267 268 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) 269 { 270 struct iov_iter i; 271 ssize_t bw; 272 273 iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len); 274 275 file_start_write(file); 276 bw = vfs_iter_write(file, &i, ppos); 277 file_end_write(file); 278 279 if (likely(bw == bvec->bv_len)) 280 return 0; 281 282 printk_ratelimited(KERN_ERR 283 "loop: Write error at byte offset %llu, length %i.\n", 284 (unsigned long long)*ppos, bvec->bv_len); 285 if (bw >= 0) 286 bw = -EIO; 287 return bw; 288 } 289 290 static int lo_write_simple(struct loop_device *lo, struct request *rq, 291 loff_t pos) 292 { 293 struct bio_vec bvec; 294 struct req_iterator iter; 295 int ret = 0; 296 297 rq_for_each_segment(bvec, rq, iter) { 298 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); 299 if (ret < 0) 300 break; 301 cond_resched(); 302 } 303 304 return ret; 305 } 306 307 /* 308 * This is the slow, transforming version that needs to double buffer the 309 * data as it cannot do the transformations in place without having direct 310 * access to the destination pages of the backing file. 311 */ 312 static int lo_write_transfer(struct loop_device *lo, struct request *rq, 313 loff_t pos) 314 { 315 struct bio_vec bvec, b; 316 struct req_iterator iter; 317 struct page *page; 318 int ret = 0; 319 320 page = alloc_page(GFP_NOIO); 321 if (unlikely(!page)) 322 return -ENOMEM; 323 324 rq_for_each_segment(bvec, rq, iter) { 325 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page, 326 bvec.bv_offset, bvec.bv_len, pos >> 9); 327 if (unlikely(ret)) 328 break; 329 330 b.bv_page = page; 331 b.bv_offset = 0; 332 b.bv_len = bvec.bv_len; 333 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos); 334 if (ret < 0) 335 break; 336 } 337 338 __free_page(page); 339 return ret; 340 } 341 342 static int lo_read_simple(struct loop_device *lo, struct request *rq, 343 loff_t pos) 344 { 345 struct bio_vec bvec; 346 struct req_iterator iter; 347 struct iov_iter i; 348 ssize_t len; 349 350 rq_for_each_segment(bvec, rq, iter) { 351 iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len); 352 len = vfs_iter_read(lo->lo_backing_file, &i, &pos); 353 if (len < 0) 354 return len; 355 356 flush_dcache_page(bvec.bv_page); 357 358 if (len != bvec.bv_len) { 359 struct bio *bio; 360 361 __rq_for_each_bio(bio, rq) 362 zero_fill_bio(bio); 363 break; 364 } 365 cond_resched(); 366 } 367 368 return 0; 369 } 370 371 static int lo_read_transfer(struct loop_device *lo, struct request *rq, 372 loff_t pos) 373 { 374 struct bio_vec bvec, b; 375 struct req_iterator iter; 376 struct iov_iter i; 377 struct page *page; 378 ssize_t len; 379 int ret = 0; 380 381 page = alloc_page(GFP_NOIO); 382 if (unlikely(!page)) 383 return -ENOMEM; 384 385 rq_for_each_segment(bvec, rq, iter) { 386 loff_t offset = pos; 387 388 b.bv_page = page; 389 b.bv_offset = 0; 390 b.bv_len = bvec.bv_len; 391 392 iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len); 393 len = vfs_iter_read(lo->lo_backing_file, &i, &pos); 394 if (len < 0) { 395 ret = len; 396 goto out_free_page; 397 } 398 399 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page, 400 bvec.bv_offset, len, offset >> 9); 401 if (ret) 402 goto out_free_page; 403 404 flush_dcache_page(bvec.bv_page); 405 406 if (len != bvec.bv_len) { 407 struct bio *bio; 408 409 __rq_for_each_bio(bio, rq) 410 zero_fill_bio(bio); 411 break; 412 } 413 } 414 415 ret = 0; 416 out_free_page: 417 __free_page(page); 418 return ret; 419 } 420 421 static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos) 422 { 423 /* 424 * We use punch hole to reclaim the free space used by the 425 * image a.k.a. discard. However we do not support discard if 426 * encryption is enabled, because it may give an attacker 427 * useful information. 428 */ 429 struct file *file = lo->lo_backing_file; 430 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE; 431 int ret; 432 433 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) { 434 ret = -EOPNOTSUPP; 435 goto out; 436 } 437 438 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); 439 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) 440 ret = -EIO; 441 out: 442 return ret; 443 } 444 445 static int lo_req_flush(struct loop_device *lo, struct request *rq) 446 { 447 struct file *file = lo->lo_backing_file; 448 int ret = vfs_fsync(file, 0); 449 if (unlikely(ret && ret != -EINVAL)) 450 ret = -EIO; 451 452 return ret; 453 } 454 455 static void lo_complete_rq(struct request *rq) 456 { 457 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 458 459 if (unlikely(req_op(cmd->rq) == REQ_OP_READ && cmd->use_aio && 460 cmd->ret >= 0 && cmd->ret < blk_rq_bytes(cmd->rq))) { 461 struct bio *bio = cmd->rq->bio; 462 463 bio_advance(bio, cmd->ret); 464 zero_fill_bio(bio); 465 } 466 467 blk_mq_end_request(rq, cmd->ret < 0 ? -EIO : 0); 468 } 469 470 static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) 471 { 472 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); 473 474 cmd->ret = ret; 475 blk_mq_complete_request(cmd->rq); 476 } 477 478 static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 479 loff_t pos, bool rw) 480 { 481 struct iov_iter iter; 482 struct bio_vec *bvec; 483 struct bio *bio = cmd->rq->bio; 484 struct file *file = lo->lo_backing_file; 485 int ret; 486 487 /* nomerge for loop request queue */ 488 WARN_ON(cmd->rq->bio != cmd->rq->biotail); 489 490 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 491 iov_iter_bvec(&iter, ITER_BVEC | rw, bvec, 492 bio_segments(bio), blk_rq_bytes(cmd->rq)); 493 /* 494 * This bio may be started from the middle of the 'bvec' 495 * because of bio splitting, so offset from the bvec must 496 * be passed to iov iterator 497 */ 498 iter.iov_offset = bio->bi_iter.bi_bvec_done; 499 500 cmd->iocb.ki_pos = pos; 501 cmd->iocb.ki_filp = file; 502 cmd->iocb.ki_complete = lo_rw_aio_complete; 503 cmd->iocb.ki_flags = IOCB_DIRECT; 504 505 if (rw == WRITE) 506 ret = call_write_iter(file, &cmd->iocb, &iter); 507 else 508 ret = call_read_iter(file, &cmd->iocb, &iter); 509 510 if (ret != -EIOCBQUEUED) 511 cmd->iocb.ki_complete(&cmd->iocb, ret, 0); 512 return 0; 513 } 514 515 static int do_req_filebacked(struct loop_device *lo, struct request *rq) 516 { 517 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 518 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; 519 520 /* 521 * lo_write_simple and lo_read_simple should have been covered 522 * by io submit style function like lo_rw_aio(), one blocker 523 * is that lo_read_simple() need to call flush_dcache_page after 524 * the page is written from kernel, and it isn't easy to handle 525 * this in io submit style function which submits all segments 526 * of the req at one time. And direct read IO doesn't need to 527 * run flush_dcache_page(). 528 */ 529 switch (req_op(rq)) { 530 case REQ_OP_FLUSH: 531 return lo_req_flush(lo, rq); 532 case REQ_OP_DISCARD: 533 case REQ_OP_WRITE_ZEROES: 534 return lo_discard(lo, rq, pos); 535 case REQ_OP_WRITE: 536 if (lo->transfer) 537 return lo_write_transfer(lo, rq, pos); 538 else if (cmd->use_aio) 539 return lo_rw_aio(lo, cmd, pos, WRITE); 540 else 541 return lo_write_simple(lo, rq, pos); 542 case REQ_OP_READ: 543 if (lo->transfer) 544 return lo_read_transfer(lo, rq, pos); 545 else if (cmd->use_aio) 546 return lo_rw_aio(lo, cmd, pos, READ); 547 else 548 return lo_read_simple(lo, rq, pos); 549 default: 550 WARN_ON_ONCE(1); 551 return -EIO; 552 break; 553 } 554 } 555 556 struct switch_request { 557 struct file *file; 558 struct completion wait; 559 }; 560 561 static inline void loop_update_dio(struct loop_device *lo) 562 { 563 __loop_update_dio(lo, io_is_direct(lo->lo_backing_file) | 564 lo->use_dio); 565 } 566 567 /* 568 * Do the actual switch; called from the BIO completion routine 569 */ 570 static void do_loop_switch(struct loop_device *lo, struct switch_request *p) 571 { 572 struct file *file = p->file; 573 struct file *old_file = lo->lo_backing_file; 574 struct address_space *mapping; 575 576 /* if no new file, only flush of queued bios requested */ 577 if (!file) 578 return; 579 580 mapping = file->f_mapping; 581 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); 582 lo->lo_backing_file = file; 583 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ? 584 mapping->host->i_bdev->bd_block_size : PAGE_SIZE; 585 lo->old_gfp_mask = mapping_gfp_mask(mapping); 586 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 587 loop_update_dio(lo); 588 } 589 590 /* 591 * loop_switch performs the hard work of switching a backing store. 592 * First it needs to flush existing IO, it does this by sending a magic 593 * BIO down the pipe. The completion of this BIO does the actual switch. 594 */ 595 static int loop_switch(struct loop_device *lo, struct file *file) 596 { 597 struct switch_request w; 598 599 w.file = file; 600 601 /* freeze queue and wait for completion of scheduled requests */ 602 blk_mq_freeze_queue(lo->lo_queue); 603 604 /* do the switch action */ 605 do_loop_switch(lo, &w); 606 607 /* unfreeze */ 608 blk_mq_unfreeze_queue(lo->lo_queue); 609 610 return 0; 611 } 612 613 /* 614 * Helper to flush the IOs in loop, but keeping loop thread running 615 */ 616 static int loop_flush(struct loop_device *lo) 617 { 618 return loop_switch(lo, NULL); 619 } 620 621 static void loop_reread_partitions(struct loop_device *lo, 622 struct block_device *bdev) 623 { 624 int rc; 625 626 /* 627 * bd_mutex has been held already in release path, so don't 628 * acquire it if this function is called in such case. 629 * 630 * If the reread partition isn't from release path, lo_refcnt 631 * must be at least one and it can only become zero when the 632 * current holder is released. 633 */ 634 if (!atomic_read(&lo->lo_refcnt)) 635 rc = __blkdev_reread_part(bdev); 636 else 637 rc = blkdev_reread_part(bdev); 638 if (rc) 639 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", 640 __func__, lo->lo_number, lo->lo_file_name, rc); 641 } 642 643 /* 644 * loop_change_fd switched the backing store of a loopback device to 645 * a new file. This is useful for operating system installers to free up 646 * the original file and in High Availability environments to switch to 647 * an alternative location for the content in case of server meltdown. 648 * This can only work if the loop device is used read-only, and if the 649 * new backing store is the same size and type as the old backing store. 650 */ 651 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 652 unsigned int arg) 653 { 654 struct file *file, *old_file; 655 struct inode *inode; 656 int error; 657 658 error = -ENXIO; 659 if (lo->lo_state != Lo_bound) 660 goto out; 661 662 /* the loop device has to be read-only */ 663 error = -EINVAL; 664 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) 665 goto out; 666 667 error = -EBADF; 668 file = fget(arg); 669 if (!file) 670 goto out; 671 672 inode = file->f_mapping->host; 673 old_file = lo->lo_backing_file; 674 675 error = -EINVAL; 676 677 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 678 goto out_putf; 679 680 /* size of the new backing store needs to be the same */ 681 if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) 682 goto out_putf; 683 684 /* and ... switch */ 685 error = loop_switch(lo, file); 686 if (error) 687 goto out_putf; 688 689 fput(old_file); 690 if (lo->lo_flags & LO_FLAGS_PARTSCAN) 691 loop_reread_partitions(lo, bdev); 692 return 0; 693 694 out_putf: 695 fput(file); 696 out: 697 return error; 698 } 699 700 static inline int is_loop_device(struct file *file) 701 { 702 struct inode *i = file->f_mapping->host; 703 704 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; 705 } 706 707 /* loop sysfs attributes */ 708 709 static ssize_t loop_attr_show(struct device *dev, char *page, 710 ssize_t (*callback)(struct loop_device *, char *)) 711 { 712 struct gendisk *disk = dev_to_disk(dev); 713 struct loop_device *lo = disk->private_data; 714 715 return callback(lo, page); 716 } 717 718 #define LOOP_ATTR_RO(_name) \ 719 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ 720 static ssize_t loop_attr_do_show_##_name(struct device *d, \ 721 struct device_attribute *attr, char *b) \ 722 { \ 723 return loop_attr_show(d, b, loop_attr_##_name##_show); \ 724 } \ 725 static struct device_attribute loop_attr_##_name = \ 726 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL); 727 728 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) 729 { 730 ssize_t ret; 731 char *p = NULL; 732 733 spin_lock_irq(&lo->lo_lock); 734 if (lo->lo_backing_file) 735 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); 736 spin_unlock_irq(&lo->lo_lock); 737 738 if (IS_ERR_OR_NULL(p)) 739 ret = PTR_ERR(p); 740 else { 741 ret = strlen(p); 742 memmove(buf, p, ret); 743 buf[ret++] = '\n'; 744 buf[ret] = 0; 745 } 746 747 return ret; 748 } 749 750 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) 751 { 752 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset); 753 } 754 755 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) 756 { 757 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); 758 } 759 760 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 761 { 762 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); 763 764 return sprintf(buf, "%s\n", autoclear ? "1" : "0"); 765 } 766 767 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) 768 { 769 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); 770 771 return sprintf(buf, "%s\n", partscan ? "1" : "0"); 772 } 773 774 static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) 775 { 776 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); 777 778 return sprintf(buf, "%s\n", dio ? "1" : "0"); 779 } 780 781 LOOP_ATTR_RO(backing_file); 782 LOOP_ATTR_RO(offset); 783 LOOP_ATTR_RO(sizelimit); 784 LOOP_ATTR_RO(autoclear); 785 LOOP_ATTR_RO(partscan); 786 LOOP_ATTR_RO(dio); 787 788 static struct attribute *loop_attrs[] = { 789 &loop_attr_backing_file.attr, 790 &loop_attr_offset.attr, 791 &loop_attr_sizelimit.attr, 792 &loop_attr_autoclear.attr, 793 &loop_attr_partscan.attr, 794 &loop_attr_dio.attr, 795 NULL, 796 }; 797 798 static struct attribute_group loop_attribute_group = { 799 .name = "loop", 800 .attrs= loop_attrs, 801 }; 802 803 static int loop_sysfs_init(struct loop_device *lo) 804 { 805 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, 806 &loop_attribute_group); 807 } 808 809 static void loop_sysfs_exit(struct loop_device *lo) 810 { 811 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, 812 &loop_attribute_group); 813 } 814 815 static void loop_config_discard(struct loop_device *lo) 816 { 817 struct file *file = lo->lo_backing_file; 818 struct inode *inode = file->f_mapping->host; 819 struct request_queue *q = lo->lo_queue; 820 int lo_bits = 9; 821 822 /* 823 * We use punch hole to reclaim the free space used by the 824 * image a.k.a. discard. However we do not support discard if 825 * encryption is enabled, because it may give an attacker 826 * useful information. 827 */ 828 if ((!file->f_op->fallocate) || 829 lo->lo_encrypt_key_size) { 830 q->limits.discard_granularity = 0; 831 q->limits.discard_alignment = 0; 832 blk_queue_max_discard_sectors(q, 0); 833 blk_queue_max_write_zeroes_sectors(q, 0); 834 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q); 835 return; 836 } 837 838 q->limits.discard_granularity = inode->i_sb->s_blocksize; 839 q->limits.discard_alignment = 0; 840 if (lo->lo_flags & LO_FLAGS_BLOCKSIZE) 841 lo_bits = blksize_bits(lo->lo_logical_blocksize); 842 843 blk_queue_max_discard_sectors(q, UINT_MAX >> lo_bits); 844 blk_queue_max_write_zeroes_sectors(q, UINT_MAX >> lo_bits); 845 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q); 846 } 847 848 static void loop_unprepare_queue(struct loop_device *lo) 849 { 850 kthread_flush_worker(&lo->worker); 851 kthread_stop(lo->worker_task); 852 } 853 854 static int loop_prepare_queue(struct loop_device *lo) 855 { 856 kthread_init_worker(&lo->worker); 857 lo->worker_task = kthread_run(kthread_worker_fn, 858 &lo->worker, "loop%d", lo->lo_number); 859 if (IS_ERR(lo->worker_task)) 860 return -ENOMEM; 861 set_user_nice(lo->worker_task, MIN_NICE); 862 return 0; 863 } 864 865 static int loop_set_fd(struct loop_device *lo, fmode_t mode, 866 struct block_device *bdev, unsigned int arg) 867 { 868 struct file *file, *f; 869 struct inode *inode; 870 struct address_space *mapping; 871 unsigned lo_blocksize; 872 int lo_flags = 0; 873 int error; 874 loff_t size; 875 876 /* This is safe, since we have a reference from open(). */ 877 __module_get(THIS_MODULE); 878 879 error = -EBADF; 880 file = fget(arg); 881 if (!file) 882 goto out; 883 884 error = -EBUSY; 885 if (lo->lo_state != Lo_unbound) 886 goto out_putf; 887 888 /* Avoid recursion */ 889 f = file; 890 while (is_loop_device(f)) { 891 struct loop_device *l; 892 893 if (f->f_mapping->host->i_bdev == bdev) 894 goto out_putf; 895 896 l = f->f_mapping->host->i_bdev->bd_disk->private_data; 897 if (l->lo_state == Lo_unbound) { 898 error = -EINVAL; 899 goto out_putf; 900 } 901 f = l->lo_backing_file; 902 } 903 904 mapping = file->f_mapping; 905 inode = mapping->host; 906 907 error = -EINVAL; 908 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 909 goto out_putf; 910 911 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || 912 !file->f_op->write_iter) 913 lo_flags |= LO_FLAGS_READ_ONLY; 914 915 lo_blocksize = S_ISBLK(inode->i_mode) ? 916 inode->i_bdev->bd_block_size : PAGE_SIZE; 917 918 error = -EFBIG; 919 size = get_loop_size(lo, file); 920 if ((loff_t)(sector_t)size != size) 921 goto out_putf; 922 error = loop_prepare_queue(lo); 923 if (error) 924 goto out_putf; 925 926 error = 0; 927 928 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0); 929 930 lo->use_dio = false; 931 lo->lo_blocksize = lo_blocksize; 932 lo->lo_logical_blocksize = 512; 933 lo->lo_device = bdev; 934 lo->lo_flags = lo_flags; 935 lo->lo_backing_file = file; 936 lo->transfer = NULL; 937 lo->ioctl = NULL; 938 lo->lo_sizelimit = 0; 939 lo->old_gfp_mask = mapping_gfp_mask(mapping); 940 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 941 942 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) 943 blk_queue_write_cache(lo->lo_queue, true, false); 944 945 loop_update_dio(lo); 946 set_capacity(lo->lo_disk, size); 947 bd_set_size(bdev, size << 9); 948 loop_sysfs_init(lo); 949 /* let user-space know about the new size */ 950 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 951 952 set_blocksize(bdev, lo_blocksize); 953 954 lo->lo_state = Lo_bound; 955 if (part_shift) 956 lo->lo_flags |= LO_FLAGS_PARTSCAN; 957 if (lo->lo_flags & LO_FLAGS_PARTSCAN) 958 loop_reread_partitions(lo, bdev); 959 960 /* Grab the block_device to prevent its destruction after we 961 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev). 962 */ 963 bdgrab(bdev); 964 return 0; 965 966 out_putf: 967 fput(file); 968 out: 969 /* This is safe: open() is still holding a reference. */ 970 module_put(THIS_MODULE); 971 return error; 972 } 973 974 static int 975 loop_release_xfer(struct loop_device *lo) 976 { 977 int err = 0; 978 struct loop_func_table *xfer = lo->lo_encryption; 979 980 if (xfer) { 981 if (xfer->release) 982 err = xfer->release(lo); 983 lo->transfer = NULL; 984 lo->lo_encryption = NULL; 985 module_put(xfer->owner); 986 } 987 return err; 988 } 989 990 static int 991 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 992 const struct loop_info64 *i) 993 { 994 int err = 0; 995 996 if (xfer) { 997 struct module *owner = xfer->owner; 998 999 if (!try_module_get(owner)) 1000 return -EINVAL; 1001 if (xfer->init) 1002 err = xfer->init(lo, i); 1003 if (err) 1004 module_put(owner); 1005 else 1006 lo->lo_encryption = xfer; 1007 } 1008 return err; 1009 } 1010 1011 static int loop_clr_fd(struct loop_device *lo) 1012 { 1013 struct file *filp = lo->lo_backing_file; 1014 gfp_t gfp = lo->old_gfp_mask; 1015 struct block_device *bdev = lo->lo_device; 1016 1017 if (lo->lo_state != Lo_bound) 1018 return -ENXIO; 1019 1020 /* 1021 * If we've explicitly asked to tear down the loop device, 1022 * and it has an elevated reference count, set it for auto-teardown when 1023 * the last reference goes away. This stops $!~#$@ udev from 1024 * preventing teardown because it decided that it needs to run blkid on 1025 * the loopback device whenever they appear. xfstests is notorious for 1026 * failing tests because blkid via udev races with a losetup 1027 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d 1028 * command to fail with EBUSY. 1029 */ 1030 if (atomic_read(&lo->lo_refcnt) > 1) { 1031 lo->lo_flags |= LO_FLAGS_AUTOCLEAR; 1032 mutex_unlock(&lo->lo_ctl_mutex); 1033 return 0; 1034 } 1035 1036 if (filp == NULL) 1037 return -EINVAL; 1038 1039 /* freeze request queue during the transition */ 1040 blk_mq_freeze_queue(lo->lo_queue); 1041 1042 spin_lock_irq(&lo->lo_lock); 1043 lo->lo_state = Lo_rundown; 1044 lo->lo_backing_file = NULL; 1045 spin_unlock_irq(&lo->lo_lock); 1046 1047 loop_release_xfer(lo); 1048 lo->transfer = NULL; 1049 lo->ioctl = NULL; 1050 lo->lo_device = NULL; 1051 lo->lo_encryption = NULL; 1052 lo->lo_offset = 0; 1053 lo->lo_sizelimit = 0; 1054 lo->lo_encrypt_key_size = 0; 1055 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); 1056 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); 1057 memset(lo->lo_file_name, 0, LO_NAME_SIZE); 1058 if (bdev) { 1059 bdput(bdev); 1060 invalidate_bdev(bdev); 1061 } 1062 set_capacity(lo->lo_disk, 0); 1063 loop_sysfs_exit(lo); 1064 if (bdev) { 1065 bd_set_size(bdev, 0); 1066 /* let user-space know about this change */ 1067 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 1068 } 1069 mapping_set_gfp_mask(filp->f_mapping, gfp); 1070 lo->lo_state = Lo_unbound; 1071 /* This is safe: open() is still holding a reference. */ 1072 module_put(THIS_MODULE); 1073 blk_mq_unfreeze_queue(lo->lo_queue); 1074 1075 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev) 1076 loop_reread_partitions(lo, bdev); 1077 lo->lo_flags = 0; 1078 if (!part_shift) 1079 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; 1080 loop_unprepare_queue(lo); 1081 mutex_unlock(&lo->lo_ctl_mutex); 1082 /* 1083 * Need not hold lo_ctl_mutex to fput backing file. 1084 * Calling fput holding lo_ctl_mutex triggers a circular 1085 * lock dependency possibility warning as fput can take 1086 * bd_mutex which is usually taken before lo_ctl_mutex. 1087 */ 1088 fput(filp); 1089 return 0; 1090 } 1091 1092 static int 1093 loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 1094 { 1095 int err; 1096 struct loop_func_table *xfer; 1097 kuid_t uid = current_uid(); 1098 int lo_flags = lo->lo_flags; 1099 1100 if (lo->lo_encrypt_key_size && 1101 !uid_eq(lo->lo_key_owner, uid) && 1102 !capable(CAP_SYS_ADMIN)) 1103 return -EPERM; 1104 if (lo->lo_state != Lo_bound) 1105 return -ENXIO; 1106 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) 1107 return -EINVAL; 1108 1109 /* I/O need to be drained during transfer transition */ 1110 blk_mq_freeze_queue(lo->lo_queue); 1111 1112 err = loop_release_xfer(lo); 1113 if (err) 1114 goto exit; 1115 1116 if (info->lo_encrypt_type) { 1117 unsigned int type = info->lo_encrypt_type; 1118 1119 if (type >= MAX_LO_CRYPT) 1120 return -EINVAL; 1121 xfer = xfer_funcs[type]; 1122 if (xfer == NULL) 1123 return -EINVAL; 1124 } else 1125 xfer = NULL; 1126 1127 err = loop_init_xfer(lo, xfer, info); 1128 if (err) 1129 goto exit; 1130 1131 if (info->lo_flags & LO_FLAGS_BLOCKSIZE) { 1132 if (!(lo->lo_flags & LO_FLAGS_BLOCKSIZE)) 1133 lo->lo_logical_blocksize = 512; 1134 lo->lo_flags |= LO_FLAGS_BLOCKSIZE; 1135 if (LO_INFO_BLOCKSIZE(info) != 512 && 1136 LO_INFO_BLOCKSIZE(info) != 1024 && 1137 LO_INFO_BLOCKSIZE(info) != 2048 && 1138 LO_INFO_BLOCKSIZE(info) != 4096) 1139 return -EINVAL; 1140 if (LO_INFO_BLOCKSIZE(info) > lo->lo_blocksize) 1141 return -EINVAL; 1142 } 1143 1144 if (lo->lo_offset != info->lo_offset || 1145 lo->lo_sizelimit != info->lo_sizelimit || 1146 lo->lo_flags != lo_flags || 1147 ((lo->lo_flags & LO_FLAGS_BLOCKSIZE) && 1148 lo->lo_logical_blocksize != LO_INFO_BLOCKSIZE(info))) { 1149 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit, 1150 LO_INFO_BLOCKSIZE(info))) 1151 err = -EFBIG; 1152 goto exit; 1153 } 1154 1155 loop_config_discard(lo); 1156 1157 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); 1158 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); 1159 lo->lo_file_name[LO_NAME_SIZE-1] = 0; 1160 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; 1161 1162 if (!xfer) 1163 xfer = &none_funcs; 1164 lo->transfer = xfer->transfer; 1165 lo->ioctl = xfer->ioctl; 1166 1167 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) != 1168 (info->lo_flags & LO_FLAGS_AUTOCLEAR)) 1169 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR; 1170 1171 lo->lo_encrypt_key_size = info->lo_encrypt_key_size; 1172 lo->lo_init[0] = info->lo_init[0]; 1173 lo->lo_init[1] = info->lo_init[1]; 1174 if (info->lo_encrypt_key_size) { 1175 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, 1176 info->lo_encrypt_key_size); 1177 lo->lo_key_owner = uid; 1178 } 1179 1180 /* update dio if lo_offset or transfer is changed */ 1181 __loop_update_dio(lo, lo->use_dio); 1182 1183 exit: 1184 blk_mq_unfreeze_queue(lo->lo_queue); 1185 1186 if (!err && (info->lo_flags & LO_FLAGS_PARTSCAN) && 1187 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) { 1188 lo->lo_flags |= LO_FLAGS_PARTSCAN; 1189 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; 1190 loop_reread_partitions(lo, lo->lo_device); 1191 } 1192 1193 return err; 1194 } 1195 1196 static int 1197 loop_get_status(struct loop_device *lo, struct loop_info64 *info) 1198 { 1199 struct file *file = lo->lo_backing_file; 1200 struct kstat stat; 1201 int error; 1202 1203 if (lo->lo_state != Lo_bound) 1204 return -ENXIO; 1205 error = vfs_getattr(&file->f_path, &stat, 1206 STATX_INO, AT_STATX_SYNC_AS_STAT); 1207 if (error) 1208 return error; 1209 memset(info, 0, sizeof(*info)); 1210 info->lo_number = lo->lo_number; 1211 info->lo_device = huge_encode_dev(stat.dev); 1212 info->lo_inode = stat.ino; 1213 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev); 1214 info->lo_offset = lo->lo_offset; 1215 info->lo_sizelimit = lo->lo_sizelimit; 1216 info->lo_flags = lo->lo_flags; 1217 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); 1218 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE); 1219 info->lo_encrypt_type = 1220 lo->lo_encryption ? lo->lo_encryption->number : 0; 1221 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) { 1222 info->lo_encrypt_key_size = lo->lo_encrypt_key_size; 1223 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key, 1224 lo->lo_encrypt_key_size); 1225 } 1226 return 0; 1227 } 1228 1229 static void 1230 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) 1231 { 1232 memset(info64, 0, sizeof(*info64)); 1233 info64->lo_number = info->lo_number; 1234 info64->lo_device = info->lo_device; 1235 info64->lo_inode = info->lo_inode; 1236 info64->lo_rdevice = info->lo_rdevice; 1237 info64->lo_offset = info->lo_offset; 1238 info64->lo_sizelimit = 0; 1239 info64->lo_encrypt_type = info->lo_encrypt_type; 1240 info64->lo_encrypt_key_size = info->lo_encrypt_key_size; 1241 info64->lo_flags = info->lo_flags; 1242 info64->lo_init[0] = info->lo_init[0]; 1243 info64->lo_init[1] = info->lo_init[1]; 1244 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1245 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE); 1246 else 1247 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); 1248 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE); 1249 } 1250 1251 static int 1252 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) 1253 { 1254 memset(info, 0, sizeof(*info)); 1255 info->lo_number = info64->lo_number; 1256 info->lo_device = info64->lo_device; 1257 info->lo_inode = info64->lo_inode; 1258 info->lo_rdevice = info64->lo_rdevice; 1259 info->lo_offset = info64->lo_offset; 1260 info->lo_encrypt_type = info64->lo_encrypt_type; 1261 info->lo_encrypt_key_size = info64->lo_encrypt_key_size; 1262 info->lo_flags = info64->lo_flags; 1263 info->lo_init[0] = info64->lo_init[0]; 1264 info->lo_init[1] = info64->lo_init[1]; 1265 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1266 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1267 else 1268 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); 1269 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1270 1271 /* error in case values were truncated */ 1272 if (info->lo_device != info64->lo_device || 1273 info->lo_rdevice != info64->lo_rdevice || 1274 info->lo_inode != info64->lo_inode || 1275 info->lo_offset != info64->lo_offset) 1276 return -EOVERFLOW; 1277 1278 return 0; 1279 } 1280 1281 static int 1282 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) 1283 { 1284 struct loop_info info; 1285 struct loop_info64 info64; 1286 1287 if (copy_from_user(&info, arg, sizeof (struct loop_info))) 1288 return -EFAULT; 1289 loop_info64_from_old(&info, &info64); 1290 return loop_set_status(lo, &info64); 1291 } 1292 1293 static int 1294 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) 1295 { 1296 struct loop_info64 info64; 1297 1298 if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) 1299 return -EFAULT; 1300 return loop_set_status(lo, &info64); 1301 } 1302 1303 static int 1304 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { 1305 struct loop_info info; 1306 struct loop_info64 info64; 1307 int err = 0; 1308 1309 if (!arg) 1310 err = -EINVAL; 1311 if (!err) 1312 err = loop_get_status(lo, &info64); 1313 if (!err) 1314 err = loop_info64_to_old(&info64, &info); 1315 if (!err && copy_to_user(arg, &info, sizeof(info))) 1316 err = -EFAULT; 1317 1318 return err; 1319 } 1320 1321 static int 1322 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { 1323 struct loop_info64 info64; 1324 int err = 0; 1325 1326 if (!arg) 1327 err = -EINVAL; 1328 if (!err) 1329 err = loop_get_status(lo, &info64); 1330 if (!err && copy_to_user(arg, &info64, sizeof(info64))) 1331 err = -EFAULT; 1332 1333 return err; 1334 } 1335 1336 static int loop_set_capacity(struct loop_device *lo) 1337 { 1338 if (unlikely(lo->lo_state != Lo_bound)) 1339 return -ENXIO; 1340 1341 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit, 1342 lo->lo_logical_blocksize); 1343 } 1344 1345 static int loop_set_dio(struct loop_device *lo, unsigned long arg) 1346 { 1347 int error = -ENXIO; 1348 if (lo->lo_state != Lo_bound) 1349 goto out; 1350 1351 __loop_update_dio(lo, !!arg); 1352 if (lo->use_dio == !!arg) 1353 return 0; 1354 error = -EINVAL; 1355 out: 1356 return error; 1357 } 1358 1359 static int lo_ioctl(struct block_device *bdev, fmode_t mode, 1360 unsigned int cmd, unsigned long arg) 1361 { 1362 struct loop_device *lo = bdev->bd_disk->private_data; 1363 int err; 1364 1365 mutex_lock_nested(&lo->lo_ctl_mutex, 1); 1366 switch (cmd) { 1367 case LOOP_SET_FD: 1368 err = loop_set_fd(lo, mode, bdev, arg); 1369 break; 1370 case LOOP_CHANGE_FD: 1371 err = loop_change_fd(lo, bdev, arg); 1372 break; 1373 case LOOP_CLR_FD: 1374 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */ 1375 err = loop_clr_fd(lo); 1376 if (!err) 1377 goto out_unlocked; 1378 break; 1379 case LOOP_SET_STATUS: 1380 err = -EPERM; 1381 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1382 err = loop_set_status_old(lo, 1383 (struct loop_info __user *)arg); 1384 break; 1385 case LOOP_GET_STATUS: 1386 err = loop_get_status_old(lo, (struct loop_info __user *) arg); 1387 break; 1388 case LOOP_SET_STATUS64: 1389 err = -EPERM; 1390 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1391 err = loop_set_status64(lo, 1392 (struct loop_info64 __user *) arg); 1393 break; 1394 case LOOP_GET_STATUS64: 1395 err = loop_get_status64(lo, (struct loop_info64 __user *) arg); 1396 break; 1397 case LOOP_SET_CAPACITY: 1398 err = -EPERM; 1399 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1400 err = loop_set_capacity(lo); 1401 break; 1402 case LOOP_SET_DIRECT_IO: 1403 err = -EPERM; 1404 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) 1405 err = loop_set_dio(lo, arg); 1406 break; 1407 default: 1408 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; 1409 } 1410 mutex_unlock(&lo->lo_ctl_mutex); 1411 1412 out_unlocked: 1413 return err; 1414 } 1415 1416 #ifdef CONFIG_COMPAT 1417 struct compat_loop_info { 1418 compat_int_t lo_number; /* ioctl r/o */ 1419 compat_dev_t lo_device; /* ioctl r/o */ 1420 compat_ulong_t lo_inode; /* ioctl r/o */ 1421 compat_dev_t lo_rdevice; /* ioctl r/o */ 1422 compat_int_t lo_offset; 1423 compat_int_t lo_encrypt_type; 1424 compat_int_t lo_encrypt_key_size; /* ioctl w/o */ 1425 compat_int_t lo_flags; /* ioctl r/o */ 1426 char lo_name[LO_NAME_SIZE]; 1427 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ 1428 compat_ulong_t lo_init[2]; 1429 char reserved[4]; 1430 }; 1431 1432 /* 1433 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info 1434 * - noinlined to reduce stack space usage in main part of driver 1435 */ 1436 static noinline int 1437 loop_info64_from_compat(const struct compat_loop_info __user *arg, 1438 struct loop_info64 *info64) 1439 { 1440 struct compat_loop_info info; 1441 1442 if (copy_from_user(&info, arg, sizeof(info))) 1443 return -EFAULT; 1444 1445 memset(info64, 0, sizeof(*info64)); 1446 info64->lo_number = info.lo_number; 1447 info64->lo_device = info.lo_device; 1448 info64->lo_inode = info.lo_inode; 1449 info64->lo_rdevice = info.lo_rdevice; 1450 info64->lo_offset = info.lo_offset; 1451 info64->lo_sizelimit = 0; 1452 info64->lo_encrypt_type = info.lo_encrypt_type; 1453 info64->lo_encrypt_key_size = info.lo_encrypt_key_size; 1454 info64->lo_flags = info.lo_flags; 1455 info64->lo_init[0] = info.lo_init[0]; 1456 info64->lo_init[1] = info.lo_init[1]; 1457 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1458 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE); 1459 else 1460 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); 1461 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE); 1462 return 0; 1463 } 1464 1465 /* 1466 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace 1467 * - noinlined to reduce stack space usage in main part of driver 1468 */ 1469 static noinline int 1470 loop_info64_to_compat(const struct loop_info64 *info64, 1471 struct compat_loop_info __user *arg) 1472 { 1473 struct compat_loop_info info; 1474 1475 memset(&info, 0, sizeof(info)); 1476 info.lo_number = info64->lo_number; 1477 info.lo_device = info64->lo_device; 1478 info.lo_inode = info64->lo_inode; 1479 info.lo_rdevice = info64->lo_rdevice; 1480 info.lo_offset = info64->lo_offset; 1481 info.lo_encrypt_type = info64->lo_encrypt_type; 1482 info.lo_encrypt_key_size = info64->lo_encrypt_key_size; 1483 info.lo_flags = info64->lo_flags; 1484 info.lo_init[0] = info64->lo_init[0]; 1485 info.lo_init[1] = info64->lo_init[1]; 1486 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1487 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1488 else 1489 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); 1490 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1491 1492 /* error in case values were truncated */ 1493 if (info.lo_device != info64->lo_device || 1494 info.lo_rdevice != info64->lo_rdevice || 1495 info.lo_inode != info64->lo_inode || 1496 info.lo_offset != info64->lo_offset || 1497 info.lo_init[0] != info64->lo_init[0] || 1498 info.lo_init[1] != info64->lo_init[1]) 1499 return -EOVERFLOW; 1500 1501 if (copy_to_user(arg, &info, sizeof(info))) 1502 return -EFAULT; 1503 return 0; 1504 } 1505 1506 static int 1507 loop_set_status_compat(struct loop_device *lo, 1508 const struct compat_loop_info __user *arg) 1509 { 1510 struct loop_info64 info64; 1511 int ret; 1512 1513 ret = loop_info64_from_compat(arg, &info64); 1514 if (ret < 0) 1515 return ret; 1516 return loop_set_status(lo, &info64); 1517 } 1518 1519 static int 1520 loop_get_status_compat(struct loop_device *lo, 1521 struct compat_loop_info __user *arg) 1522 { 1523 struct loop_info64 info64; 1524 int err = 0; 1525 1526 if (!arg) 1527 err = -EINVAL; 1528 if (!err) 1529 err = loop_get_status(lo, &info64); 1530 if (!err) 1531 err = loop_info64_to_compat(&info64, arg); 1532 return err; 1533 } 1534 1535 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 1536 unsigned int cmd, unsigned long arg) 1537 { 1538 struct loop_device *lo = bdev->bd_disk->private_data; 1539 int err; 1540 1541 switch(cmd) { 1542 case LOOP_SET_STATUS: 1543 mutex_lock(&lo->lo_ctl_mutex); 1544 err = loop_set_status_compat( 1545 lo, (const struct compat_loop_info __user *) arg); 1546 mutex_unlock(&lo->lo_ctl_mutex); 1547 break; 1548 case LOOP_GET_STATUS: 1549 mutex_lock(&lo->lo_ctl_mutex); 1550 err = loop_get_status_compat( 1551 lo, (struct compat_loop_info __user *) arg); 1552 mutex_unlock(&lo->lo_ctl_mutex); 1553 break; 1554 case LOOP_SET_CAPACITY: 1555 case LOOP_CLR_FD: 1556 case LOOP_GET_STATUS64: 1557 case LOOP_SET_STATUS64: 1558 arg = (unsigned long) compat_ptr(arg); 1559 case LOOP_SET_FD: 1560 case LOOP_CHANGE_FD: 1561 err = lo_ioctl(bdev, mode, cmd, arg); 1562 break; 1563 default: 1564 err = -ENOIOCTLCMD; 1565 break; 1566 } 1567 return err; 1568 } 1569 #endif 1570 1571 static int lo_open(struct block_device *bdev, fmode_t mode) 1572 { 1573 struct loop_device *lo; 1574 int err = 0; 1575 1576 mutex_lock(&loop_index_mutex); 1577 lo = bdev->bd_disk->private_data; 1578 if (!lo) { 1579 err = -ENXIO; 1580 goto out; 1581 } 1582 1583 atomic_inc(&lo->lo_refcnt); 1584 out: 1585 mutex_unlock(&loop_index_mutex); 1586 return err; 1587 } 1588 1589 static void lo_release(struct gendisk *disk, fmode_t mode) 1590 { 1591 struct loop_device *lo = disk->private_data; 1592 int err; 1593 1594 if (atomic_dec_return(&lo->lo_refcnt)) 1595 return; 1596 1597 mutex_lock(&lo->lo_ctl_mutex); 1598 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { 1599 /* 1600 * In autoclear mode, stop the loop thread 1601 * and remove configuration after last close. 1602 */ 1603 err = loop_clr_fd(lo); 1604 if (!err) 1605 return; 1606 } else { 1607 /* 1608 * Otherwise keep thread (if running) and config, 1609 * but flush possible ongoing bios in thread. 1610 */ 1611 loop_flush(lo); 1612 } 1613 1614 mutex_unlock(&lo->lo_ctl_mutex); 1615 } 1616 1617 static const struct block_device_operations lo_fops = { 1618 .owner = THIS_MODULE, 1619 .open = lo_open, 1620 .release = lo_release, 1621 .ioctl = lo_ioctl, 1622 #ifdef CONFIG_COMPAT 1623 .compat_ioctl = lo_compat_ioctl, 1624 #endif 1625 }; 1626 1627 /* 1628 * And now the modules code and kernel interface. 1629 */ 1630 static int max_loop; 1631 module_param(max_loop, int, S_IRUGO); 1632 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); 1633 module_param(max_part, int, S_IRUGO); 1634 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); 1635 MODULE_LICENSE("GPL"); 1636 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); 1637 1638 int loop_register_transfer(struct loop_func_table *funcs) 1639 { 1640 unsigned int n = funcs->number; 1641 1642 if (n >= MAX_LO_CRYPT || xfer_funcs[n]) 1643 return -EINVAL; 1644 xfer_funcs[n] = funcs; 1645 return 0; 1646 } 1647 1648 static int unregister_transfer_cb(int id, void *ptr, void *data) 1649 { 1650 struct loop_device *lo = ptr; 1651 struct loop_func_table *xfer = data; 1652 1653 mutex_lock(&lo->lo_ctl_mutex); 1654 if (lo->lo_encryption == xfer) 1655 loop_release_xfer(lo); 1656 mutex_unlock(&lo->lo_ctl_mutex); 1657 return 0; 1658 } 1659 1660 int loop_unregister_transfer(int number) 1661 { 1662 unsigned int n = number; 1663 struct loop_func_table *xfer; 1664 1665 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) 1666 return -EINVAL; 1667 1668 xfer_funcs[n] = NULL; 1669 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer); 1670 return 0; 1671 } 1672 1673 EXPORT_SYMBOL(loop_register_transfer); 1674 EXPORT_SYMBOL(loop_unregister_transfer); 1675 1676 static int loop_queue_rq(struct blk_mq_hw_ctx *hctx, 1677 const struct blk_mq_queue_data *bd) 1678 { 1679 struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq); 1680 struct loop_device *lo = cmd->rq->q->queuedata; 1681 1682 blk_mq_start_request(bd->rq); 1683 1684 if (lo->lo_state != Lo_bound) 1685 return BLK_MQ_RQ_QUEUE_ERROR; 1686 1687 switch (req_op(cmd->rq)) { 1688 case REQ_OP_FLUSH: 1689 case REQ_OP_DISCARD: 1690 case REQ_OP_WRITE_ZEROES: 1691 cmd->use_aio = false; 1692 break; 1693 default: 1694 cmd->use_aio = lo->use_dio; 1695 break; 1696 } 1697 1698 kthread_queue_work(&lo->worker, &cmd->work); 1699 1700 return BLK_MQ_RQ_QUEUE_OK; 1701 } 1702 1703 static void loop_handle_cmd(struct loop_cmd *cmd) 1704 { 1705 const bool write = op_is_write(req_op(cmd->rq)); 1706 struct loop_device *lo = cmd->rq->q->queuedata; 1707 int ret = 0; 1708 1709 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { 1710 ret = -EIO; 1711 goto failed; 1712 } 1713 1714 ret = do_req_filebacked(lo, cmd->rq); 1715 failed: 1716 /* complete non-aio request */ 1717 if (!cmd->use_aio || ret) { 1718 cmd->ret = ret ? -EIO : 0; 1719 blk_mq_complete_request(cmd->rq); 1720 } 1721 } 1722 1723 static void loop_queue_work(struct kthread_work *work) 1724 { 1725 struct loop_cmd *cmd = 1726 container_of(work, struct loop_cmd, work); 1727 1728 loop_handle_cmd(cmd); 1729 } 1730 1731 static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq, 1732 unsigned int hctx_idx, unsigned int numa_node) 1733 { 1734 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 1735 1736 cmd->rq = rq; 1737 kthread_init_work(&cmd->work, loop_queue_work); 1738 1739 return 0; 1740 } 1741 1742 static const struct blk_mq_ops loop_mq_ops = { 1743 .queue_rq = loop_queue_rq, 1744 .init_request = loop_init_request, 1745 .complete = lo_complete_rq, 1746 }; 1747 1748 static int loop_add(struct loop_device **l, int i) 1749 { 1750 struct loop_device *lo; 1751 struct gendisk *disk; 1752 int err; 1753 1754 err = -ENOMEM; 1755 lo = kzalloc(sizeof(*lo), GFP_KERNEL); 1756 if (!lo) 1757 goto out; 1758 1759 lo->lo_state = Lo_unbound; 1760 1761 /* allocate id, if @id >= 0, we're requesting that specific id */ 1762 if (i >= 0) { 1763 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); 1764 if (err == -ENOSPC) 1765 err = -EEXIST; 1766 } else { 1767 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); 1768 } 1769 if (err < 0) 1770 goto out_free_dev; 1771 i = err; 1772 1773 err = -ENOMEM; 1774 lo->tag_set.ops = &loop_mq_ops; 1775 lo->tag_set.nr_hw_queues = 1; 1776 lo->tag_set.queue_depth = 128; 1777 lo->tag_set.numa_node = NUMA_NO_NODE; 1778 lo->tag_set.cmd_size = sizeof(struct loop_cmd); 1779 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 1780 lo->tag_set.driver_data = lo; 1781 1782 err = blk_mq_alloc_tag_set(&lo->tag_set); 1783 if (err) 1784 goto out_free_idr; 1785 1786 lo->lo_queue = blk_mq_init_queue(&lo->tag_set); 1787 if (IS_ERR_OR_NULL(lo->lo_queue)) { 1788 err = PTR_ERR(lo->lo_queue); 1789 goto out_cleanup_tags; 1790 } 1791 lo->lo_queue->queuedata = lo; 1792 1793 /* 1794 * It doesn't make sense to enable merge because the I/O 1795 * submitted to backing file is handled page by page. 1796 */ 1797 queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES, lo->lo_queue); 1798 1799 err = -ENOMEM; 1800 disk = lo->lo_disk = alloc_disk(1 << part_shift); 1801 if (!disk) 1802 goto out_free_queue; 1803 1804 /* 1805 * Disable partition scanning by default. The in-kernel partition 1806 * scanning can be requested individually per-device during its 1807 * setup. Userspace can always add and remove partitions from all 1808 * devices. The needed partition minors are allocated from the 1809 * extended minor space, the main loop device numbers will continue 1810 * to match the loop minors, regardless of the number of partitions 1811 * used. 1812 * 1813 * If max_part is given, partition scanning is globally enabled for 1814 * all loop devices. The minors for the main loop devices will be 1815 * multiples of max_part. 1816 * 1817 * Note: Global-for-all-devices, set-only-at-init, read-only module 1818 * parameteters like 'max_loop' and 'max_part' make things needlessly 1819 * complicated, are too static, inflexible and may surprise 1820 * userspace tools. Parameters like this in general should be avoided. 1821 */ 1822 if (!part_shift) 1823 disk->flags |= GENHD_FL_NO_PART_SCAN; 1824 disk->flags |= GENHD_FL_EXT_DEVT; 1825 mutex_init(&lo->lo_ctl_mutex); 1826 atomic_set(&lo->lo_refcnt, 0); 1827 lo->lo_number = i; 1828 spin_lock_init(&lo->lo_lock); 1829 disk->major = LOOP_MAJOR; 1830 disk->first_minor = i << part_shift; 1831 disk->fops = &lo_fops; 1832 disk->private_data = lo; 1833 disk->queue = lo->lo_queue; 1834 sprintf(disk->disk_name, "loop%d", i); 1835 add_disk(disk); 1836 *l = lo; 1837 return lo->lo_number; 1838 1839 out_free_queue: 1840 blk_cleanup_queue(lo->lo_queue); 1841 out_cleanup_tags: 1842 blk_mq_free_tag_set(&lo->tag_set); 1843 out_free_idr: 1844 idr_remove(&loop_index_idr, i); 1845 out_free_dev: 1846 kfree(lo); 1847 out: 1848 return err; 1849 } 1850 1851 static void loop_remove(struct loop_device *lo) 1852 { 1853 blk_cleanup_queue(lo->lo_queue); 1854 del_gendisk(lo->lo_disk); 1855 blk_mq_free_tag_set(&lo->tag_set); 1856 put_disk(lo->lo_disk); 1857 kfree(lo); 1858 } 1859 1860 static int find_free_cb(int id, void *ptr, void *data) 1861 { 1862 struct loop_device *lo = ptr; 1863 struct loop_device **l = data; 1864 1865 if (lo->lo_state == Lo_unbound) { 1866 *l = lo; 1867 return 1; 1868 } 1869 return 0; 1870 } 1871 1872 static int loop_lookup(struct loop_device **l, int i) 1873 { 1874 struct loop_device *lo; 1875 int ret = -ENODEV; 1876 1877 if (i < 0) { 1878 int err; 1879 1880 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo); 1881 if (err == 1) { 1882 *l = lo; 1883 ret = lo->lo_number; 1884 } 1885 goto out; 1886 } 1887 1888 /* lookup and return a specific i */ 1889 lo = idr_find(&loop_index_idr, i); 1890 if (lo) { 1891 *l = lo; 1892 ret = lo->lo_number; 1893 } 1894 out: 1895 return ret; 1896 } 1897 1898 static struct kobject *loop_probe(dev_t dev, int *part, void *data) 1899 { 1900 struct loop_device *lo; 1901 struct kobject *kobj; 1902 int err; 1903 1904 mutex_lock(&loop_index_mutex); 1905 err = loop_lookup(&lo, MINOR(dev) >> part_shift); 1906 if (err < 0) 1907 err = loop_add(&lo, MINOR(dev) >> part_shift); 1908 if (err < 0) 1909 kobj = NULL; 1910 else 1911 kobj = get_disk(lo->lo_disk); 1912 mutex_unlock(&loop_index_mutex); 1913 1914 *part = 0; 1915 return kobj; 1916 } 1917 1918 static long loop_control_ioctl(struct file *file, unsigned int cmd, 1919 unsigned long parm) 1920 { 1921 struct loop_device *lo; 1922 int ret = -ENOSYS; 1923 1924 mutex_lock(&loop_index_mutex); 1925 switch (cmd) { 1926 case LOOP_CTL_ADD: 1927 ret = loop_lookup(&lo, parm); 1928 if (ret >= 0) { 1929 ret = -EEXIST; 1930 break; 1931 } 1932 ret = loop_add(&lo, parm); 1933 break; 1934 case LOOP_CTL_REMOVE: 1935 ret = loop_lookup(&lo, parm); 1936 if (ret < 0) 1937 break; 1938 mutex_lock(&lo->lo_ctl_mutex); 1939 if (lo->lo_state != Lo_unbound) { 1940 ret = -EBUSY; 1941 mutex_unlock(&lo->lo_ctl_mutex); 1942 break; 1943 } 1944 if (atomic_read(&lo->lo_refcnt) > 0) { 1945 ret = -EBUSY; 1946 mutex_unlock(&lo->lo_ctl_mutex); 1947 break; 1948 } 1949 lo->lo_disk->private_data = NULL; 1950 mutex_unlock(&lo->lo_ctl_mutex); 1951 idr_remove(&loop_index_idr, lo->lo_number); 1952 loop_remove(lo); 1953 break; 1954 case LOOP_CTL_GET_FREE: 1955 ret = loop_lookup(&lo, -1); 1956 if (ret >= 0) 1957 break; 1958 ret = loop_add(&lo, -1); 1959 } 1960 mutex_unlock(&loop_index_mutex); 1961 1962 return ret; 1963 } 1964 1965 static const struct file_operations loop_ctl_fops = { 1966 .open = nonseekable_open, 1967 .unlocked_ioctl = loop_control_ioctl, 1968 .compat_ioctl = loop_control_ioctl, 1969 .owner = THIS_MODULE, 1970 .llseek = noop_llseek, 1971 }; 1972 1973 static struct miscdevice loop_misc = { 1974 .minor = LOOP_CTRL_MINOR, 1975 .name = "loop-control", 1976 .fops = &loop_ctl_fops, 1977 }; 1978 1979 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); 1980 MODULE_ALIAS("devname:loop-control"); 1981 1982 static int __init loop_init(void) 1983 { 1984 int i, nr; 1985 unsigned long range; 1986 struct loop_device *lo; 1987 int err; 1988 1989 err = misc_register(&loop_misc); 1990 if (err < 0) 1991 return err; 1992 1993 part_shift = 0; 1994 if (max_part > 0) { 1995 part_shift = fls(max_part); 1996 1997 /* 1998 * Adjust max_part according to part_shift as it is exported 1999 * to user space so that user can decide correct minor number 2000 * if [s]he want to create more devices. 2001 * 2002 * Note that -1 is required because partition 0 is reserved 2003 * for the whole disk. 2004 */ 2005 max_part = (1UL << part_shift) - 1; 2006 } 2007 2008 if ((1UL << part_shift) > DISK_MAX_PARTS) { 2009 err = -EINVAL; 2010 goto misc_out; 2011 } 2012 2013 if (max_loop > 1UL << (MINORBITS - part_shift)) { 2014 err = -EINVAL; 2015 goto misc_out; 2016 } 2017 2018 /* 2019 * If max_loop is specified, create that many devices upfront. 2020 * This also becomes a hard limit. If max_loop is not specified, 2021 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module 2022 * init time. Loop devices can be requested on-demand with the 2023 * /dev/loop-control interface, or be instantiated by accessing 2024 * a 'dead' device node. 2025 */ 2026 if (max_loop) { 2027 nr = max_loop; 2028 range = max_loop << part_shift; 2029 } else { 2030 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; 2031 range = 1UL << MINORBITS; 2032 } 2033 2034 if (register_blkdev(LOOP_MAJOR, "loop")) { 2035 err = -EIO; 2036 goto misc_out; 2037 } 2038 2039 blk_register_region(MKDEV(LOOP_MAJOR, 0), range, 2040 THIS_MODULE, loop_probe, NULL, NULL); 2041 2042 /* pre-create number of devices given by config or max_loop */ 2043 mutex_lock(&loop_index_mutex); 2044 for (i = 0; i < nr; i++) 2045 loop_add(&lo, i); 2046 mutex_unlock(&loop_index_mutex); 2047 2048 printk(KERN_INFO "loop: module loaded\n"); 2049 return 0; 2050 2051 misc_out: 2052 misc_deregister(&loop_misc); 2053 return err; 2054 } 2055 2056 static int loop_exit_cb(int id, void *ptr, void *data) 2057 { 2058 struct loop_device *lo = ptr; 2059 2060 loop_remove(lo); 2061 return 0; 2062 } 2063 2064 static void __exit loop_exit(void) 2065 { 2066 unsigned long range; 2067 2068 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; 2069 2070 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); 2071 idr_destroy(&loop_index_idr); 2072 2073 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); 2074 unregister_blkdev(LOOP_MAJOR, "loop"); 2075 2076 misc_deregister(&loop_misc); 2077 } 2078 2079 module_init(loop_init); 2080 module_exit(loop_exit); 2081 2082 #ifndef MODULE 2083 static int __init max_loop_setup(char *str) 2084 { 2085 max_loop = simple_strtol(str, NULL, 0); 2086 return 1; 2087 } 2088 2089 __setup("max_loop=", max_loop_setup); 2090 #endif 2091