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 <linux/ioprio.h> 80#include <linux/blk-cgroup.h> 81 82#include "loop.h" 83 84#include <linux/uaccess.h> 85 86static DEFINE_IDR(loop_index_idr); 87static DEFINE_MUTEX(loop_ctl_mutex); 88 89static int max_part; 90static int part_shift; 91 92static int transfer_xor(struct loop_device *lo, int cmd, 93 struct page *raw_page, unsigned raw_off, 94 struct page *loop_page, unsigned loop_off, 95 int size, sector_t real_block) 96{ 97 char *raw_buf = kmap_atomic(raw_page) + raw_off; 98 char *loop_buf = kmap_atomic(loop_page) + loop_off; 99 char *in, *out, *key; 100 int i, keysize; 101 102 if (cmd == READ) { 103 in = raw_buf; 104 out = loop_buf; 105 } else { 106 in = loop_buf; 107 out = raw_buf; 108 } 109 110 key = lo->lo_encrypt_key; 111 keysize = lo->lo_encrypt_key_size; 112 for (i = 0; i < size; i++) 113 *out++ = *in++ ^ key[(i & 511) % keysize]; 114 115 kunmap_atomic(loop_buf); 116 kunmap_atomic(raw_buf); 117 cond_resched(); 118 return 0; 119} 120 121static int xor_init(struct loop_device *lo, const struct loop_info64 *info) 122{ 123 if (unlikely(info->lo_encrypt_key_size <= 0)) 124 return -EINVAL; 125 return 0; 126} 127 128static struct loop_func_table none_funcs = { 129 .number = LO_CRYPT_NONE, 130}; 131 132static struct loop_func_table xor_funcs = { 133 .number = LO_CRYPT_XOR, 134 .transfer = transfer_xor, 135 .init = xor_init 136}; 137 138/* xfer_funcs[0] is special - its release function is never called */ 139static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = { 140 &none_funcs, 141 &xor_funcs 142}; 143 144static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) 145{ 146 loff_t loopsize; 147 148 /* Compute loopsize in bytes */ 149 loopsize = i_size_read(file->f_mapping->host); 150 if (offset > 0) 151 loopsize -= offset; 152 /* offset is beyond i_size, weird but possible */ 153 if (loopsize < 0) 154 return 0; 155 156 if (sizelimit > 0 && sizelimit < loopsize) 157 loopsize = sizelimit; 158 /* 159 * Unfortunately, if we want to do I/O on the device, 160 * the number of 512-byte sectors has to fit into a sector_t. 161 */ 162 return loopsize >> 9; 163} 164 165static loff_t get_loop_size(struct loop_device *lo, struct file *file) 166{ 167 return get_size(lo->lo_offset, lo->lo_sizelimit, file); 168} 169 170static void __loop_update_dio(struct loop_device *lo, bool dio) 171{ 172 struct file *file = lo->lo_backing_file; 173 struct address_space *mapping = file->f_mapping; 174 struct inode *inode = mapping->host; 175 unsigned short sb_bsize = 0; 176 unsigned dio_align = 0; 177 bool use_dio; 178 179 if (inode->i_sb->s_bdev) { 180 sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev); 181 dio_align = sb_bsize - 1; 182 } 183 184 /* 185 * We support direct I/O only if lo_offset is aligned with the 186 * logical I/O size of backing device, and the logical block 187 * size of loop is bigger than the backing device's and the loop 188 * needn't transform transfer. 189 * 190 * TODO: the above condition may be loosed in the future, and 191 * direct I/O may be switched runtime at that time because most 192 * of requests in sane applications should be PAGE_SIZE aligned 193 */ 194 if (dio) { 195 if (queue_logical_block_size(lo->lo_queue) >= sb_bsize && 196 !(lo->lo_offset & dio_align) && 197 mapping->a_ops->direct_IO && 198 !lo->transfer) 199 use_dio = true; 200 else 201 use_dio = false; 202 } else { 203 use_dio = false; 204 } 205 206 if (lo->use_dio == use_dio) 207 return; 208 209 /* flush dirty pages before changing direct IO */ 210 vfs_fsync(file, 0); 211 212 /* 213 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with 214 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup 215 * will get updated by ioctl(LOOP_GET_STATUS) 216 */ 217 if (lo->lo_state == Lo_bound) 218 blk_mq_freeze_queue(lo->lo_queue); 219 lo->use_dio = use_dio; 220 if (use_dio) { 221 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue); 222 lo->lo_flags |= LO_FLAGS_DIRECT_IO; 223 } else { 224 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); 225 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; 226 } 227 if (lo->lo_state == Lo_bound) 228 blk_mq_unfreeze_queue(lo->lo_queue); 229} 230 231/** 232 * loop_set_size() - sets device size and notifies userspace 233 * @lo: struct loop_device to set the size for 234 * @size: new size of the loop device 235 * 236 * Callers must validate that the size passed into this function fits into 237 * a sector_t, eg using loop_validate_size() 238 */ 239static void loop_set_size(struct loop_device *lo, loff_t size) 240{ 241 struct block_device *bdev = lo->lo_device; 242 243 bd_set_nr_sectors(bdev, size); 244 245 if (!set_capacity_revalidate_and_notify(lo->lo_disk, size, false)) 246 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 247} 248 249static inline int 250lo_do_transfer(struct loop_device *lo, int cmd, 251 struct page *rpage, unsigned roffs, 252 struct page *lpage, unsigned loffs, 253 int size, sector_t rblock) 254{ 255 int ret; 256 257 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock); 258 if (likely(!ret)) 259 return 0; 260 261 printk_ratelimited(KERN_ERR 262 "loop: Transfer error at byte offset %llu, length %i.\n", 263 (unsigned long long)rblock << 9, size); 264 return ret; 265} 266 267static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) 268{ 269 struct iov_iter i; 270 ssize_t bw; 271 272 iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len); 273 274 file_start_write(file); 275 bw = vfs_iter_write(file, &i, ppos, 0); 276 file_end_write(file); 277 278 if (likely(bw == bvec->bv_len)) 279 return 0; 280 281 printk_ratelimited(KERN_ERR 282 "loop: Write error at byte offset %llu, length %i.\n", 283 (unsigned long long)*ppos, bvec->bv_len); 284 if (bw >= 0) 285 bw = -EIO; 286 return bw; 287} 288 289static int lo_write_simple(struct loop_device *lo, struct request *rq, 290 loff_t pos) 291{ 292 struct bio_vec bvec; 293 struct req_iterator iter; 294 int ret = 0; 295 296 rq_for_each_segment(bvec, rq, iter) { 297 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); 298 if (ret < 0) 299 break; 300 cond_resched(); 301 } 302 303 return ret; 304} 305 306/* 307 * This is the slow, transforming version that needs to double buffer the 308 * data as it cannot do the transformations in place without having direct 309 * access to the destination pages of the backing file. 310 */ 311static int lo_write_transfer(struct loop_device *lo, struct request *rq, 312 loff_t pos) 313{ 314 struct bio_vec bvec, b; 315 struct req_iterator iter; 316 struct page *page; 317 int ret = 0; 318 319 page = alloc_page(GFP_NOIO); 320 if (unlikely(!page)) 321 return -ENOMEM; 322 323 rq_for_each_segment(bvec, rq, iter) { 324 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page, 325 bvec.bv_offset, bvec.bv_len, pos >> 9); 326 if (unlikely(ret)) 327 break; 328 329 b.bv_page = page; 330 b.bv_offset = 0; 331 b.bv_len = bvec.bv_len; 332 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos); 333 if (ret < 0) 334 break; 335 } 336 337 __free_page(page); 338 return ret; 339} 340 341static int lo_read_simple(struct loop_device *lo, struct request *rq, 342 loff_t pos) 343{ 344 struct bio_vec bvec; 345 struct req_iterator iter; 346 struct iov_iter i; 347 ssize_t len; 348 349 rq_for_each_segment(bvec, rq, iter) { 350 iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len); 351 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); 352 if (len < 0) 353 return len; 354 355 flush_dcache_page(bvec.bv_page); 356 357 if (len != bvec.bv_len) { 358 struct bio *bio; 359 360 __rq_for_each_bio(bio, rq) 361 zero_fill_bio(bio); 362 break; 363 } 364 cond_resched(); 365 } 366 367 return 0; 368} 369 370static int lo_read_transfer(struct loop_device *lo, struct request *rq, 371 loff_t pos) 372{ 373 struct bio_vec bvec, b; 374 struct req_iterator iter; 375 struct iov_iter i; 376 struct page *page; 377 ssize_t len; 378 int ret = 0; 379 380 page = alloc_page(GFP_NOIO); 381 if (unlikely(!page)) 382 return -ENOMEM; 383 384 rq_for_each_segment(bvec, rq, iter) { 385 loff_t offset = pos; 386 387 b.bv_page = page; 388 b.bv_offset = 0; 389 b.bv_len = bvec.bv_len; 390 391 iov_iter_bvec(&i, READ, &b, 1, b.bv_len); 392 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); 393 if (len < 0) { 394 ret = len; 395 goto out_free_page; 396 } 397 398 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page, 399 bvec.bv_offset, len, offset >> 9); 400 if (ret) 401 goto out_free_page; 402 403 flush_dcache_page(bvec.bv_page); 404 405 if (len != bvec.bv_len) { 406 struct bio *bio; 407 408 __rq_for_each_bio(bio, rq) 409 zero_fill_bio(bio); 410 break; 411 } 412 } 413 414 ret = 0; 415out_free_page: 416 __free_page(page); 417 return ret; 418} 419 420static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, 421 int mode) 422{ 423 /* 424 * We use fallocate to manipulate the space mappings used by the image 425 * a.k.a. discard/zerorange. However we do not support this if 426 * encryption is enabled, because it may give an attacker useful 427 * information. 428 */ 429 struct file *file = lo->lo_backing_file; 430 struct request_queue *q = lo->lo_queue; 431 int ret; 432 433 mode |= FALLOC_FL_KEEP_SIZE; 434 435 if (!blk_queue_discard(q)) { 436 ret = -EOPNOTSUPP; 437 goto out; 438 } 439 440 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); 441 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) 442 ret = -EIO; 443 out: 444 return ret; 445} 446 447static int lo_req_flush(struct loop_device *lo, struct request *rq) 448{ 449 struct file *file = lo->lo_backing_file; 450 int ret = vfs_fsync(file, 0); 451 if (unlikely(ret && ret != -EINVAL)) 452 ret = -EIO; 453 454 return ret; 455} 456 457static void lo_complete_rq(struct request *rq) 458{ 459 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 460 blk_status_t ret = BLK_STS_OK; 461 462 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || 463 req_op(rq) != REQ_OP_READ) { 464 if (cmd->ret < 0) 465 ret = errno_to_blk_status(cmd->ret); 466 goto end_io; 467 } 468 469 /* 470 * Short READ - if we got some data, advance our request and 471 * retry it. If we got no data, end the rest with EIO. 472 */ 473 if (cmd->ret) { 474 blk_update_request(rq, BLK_STS_OK, cmd->ret); 475 cmd->ret = 0; 476 blk_mq_requeue_request(rq, true); 477 } else { 478 if (cmd->use_aio) { 479 struct bio *bio = rq->bio; 480 481 while (bio) { 482 zero_fill_bio(bio); 483 bio = bio->bi_next; 484 } 485 } 486 ret = BLK_STS_IOERR; 487end_io: 488 blk_mq_end_request(rq, ret); 489 } 490} 491 492static void lo_rw_aio_do_completion(struct loop_cmd *cmd) 493{ 494 struct request *rq = blk_mq_rq_from_pdu(cmd); 495 496 if (!atomic_dec_and_test(&cmd->ref)) 497 return; 498 kfree(cmd->bvec); 499 cmd->bvec = NULL; 500 if (likely(!blk_should_fake_timeout(rq->q))) 501 blk_mq_complete_request(rq); 502} 503 504static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2) 505{ 506 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); 507 508 if (cmd->css) 509 css_put(cmd->css); 510 cmd->ret = ret; 511 lo_rw_aio_do_completion(cmd); 512} 513 514static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 515 loff_t pos, bool rw) 516{ 517 struct iov_iter iter; 518 struct req_iterator rq_iter; 519 struct bio_vec *bvec; 520 struct request *rq = blk_mq_rq_from_pdu(cmd); 521 struct bio *bio = rq->bio; 522 struct file *file = lo->lo_backing_file; 523 struct bio_vec tmp; 524 unsigned int offset; 525 int nr_bvec = 0; 526 int ret; 527 528 rq_for_each_bvec(tmp, rq, rq_iter) 529 nr_bvec++; 530 531 if (rq->bio != rq->biotail) { 532 533 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), 534 GFP_NOIO); 535 if (!bvec) 536 return -EIO; 537 cmd->bvec = bvec; 538 539 /* 540 * The bios of the request may be started from the middle of 541 * the 'bvec' because of bio splitting, so we can't directly 542 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec 543 * API will take care of all details for us. 544 */ 545 rq_for_each_bvec(tmp, rq, rq_iter) { 546 *bvec = tmp; 547 bvec++; 548 } 549 bvec = cmd->bvec; 550 offset = 0; 551 } else { 552 /* 553 * Same here, this bio may be started from the middle of the 554 * 'bvec' because of bio splitting, so offset from the bvec 555 * must be passed to iov iterator 556 */ 557 offset = bio->bi_iter.bi_bvec_done; 558 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 559 } 560 atomic_set(&cmd->ref, 2); 561 562 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); 563 iter.iov_offset = offset; 564 565 cmd->iocb.ki_pos = pos; 566 cmd->iocb.ki_filp = file; 567 cmd->iocb.ki_complete = lo_rw_aio_complete; 568 cmd->iocb.ki_flags = IOCB_DIRECT; 569 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); 570 if (cmd->css) 571 kthread_associate_blkcg(cmd->css); 572 573 if (rw == WRITE) 574 ret = call_write_iter(file, &cmd->iocb, &iter); 575 else 576 ret = call_read_iter(file, &cmd->iocb, &iter); 577 578 lo_rw_aio_do_completion(cmd); 579 kthread_associate_blkcg(NULL); 580 581 if (ret != -EIOCBQUEUED) 582 cmd->iocb.ki_complete(&cmd->iocb, ret, 0); 583 return 0; 584} 585 586static int do_req_filebacked(struct loop_device *lo, struct request *rq) 587{ 588 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 589 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; 590 591 /* 592 * lo_write_simple and lo_read_simple should have been covered 593 * by io submit style function like lo_rw_aio(), one blocker 594 * is that lo_read_simple() need to call flush_dcache_page after 595 * the page is written from kernel, and it isn't easy to handle 596 * this in io submit style function which submits all segments 597 * of the req at one time. And direct read IO doesn't need to 598 * run flush_dcache_page(). 599 */ 600 switch (req_op(rq)) { 601 case REQ_OP_FLUSH: 602 return lo_req_flush(lo, rq); 603 case REQ_OP_WRITE_ZEROES: 604 /* 605 * If the caller doesn't want deallocation, call zeroout to 606 * write zeroes the range. Otherwise, punch them out. 607 */ 608 return lo_fallocate(lo, rq, pos, 609 (rq->cmd_flags & REQ_NOUNMAP) ? 610 FALLOC_FL_ZERO_RANGE : 611 FALLOC_FL_PUNCH_HOLE); 612 case REQ_OP_DISCARD: 613 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); 614 case REQ_OP_WRITE: 615 if (lo->transfer) 616 return lo_write_transfer(lo, rq, pos); 617 else if (cmd->use_aio) 618 return lo_rw_aio(lo, cmd, pos, WRITE); 619 else 620 return lo_write_simple(lo, rq, pos); 621 case REQ_OP_READ: 622 if (lo->transfer) 623 return lo_read_transfer(lo, rq, pos); 624 else if (cmd->use_aio) 625 return lo_rw_aio(lo, cmd, pos, READ); 626 else 627 return lo_read_simple(lo, rq, pos); 628 default: 629 WARN_ON_ONCE(1); 630 return -EIO; 631 } 632} 633 634static inline void loop_update_dio(struct loop_device *lo) 635{ 636 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) | 637 lo->use_dio); 638} 639 640static void loop_reread_partitions(struct loop_device *lo, 641 struct block_device *bdev) 642{ 643 int rc; 644 645 mutex_lock(&bdev->bd_mutex); 646 rc = bdev_disk_changed(bdev, false); 647 mutex_unlock(&bdev->bd_mutex); 648 if (rc) 649 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", 650 __func__, lo->lo_number, lo->lo_file_name, rc); 651} 652 653static inline int is_loop_device(struct file *file) 654{ 655 struct inode *i = file->f_mapping->host; 656 657 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR; 658} 659 660static int loop_validate_file(struct file *file, struct block_device *bdev) 661{ 662 struct inode *inode = file->f_mapping->host; 663 struct file *f = file; 664 665 /* Avoid recursion */ 666 while (is_loop_device(f)) { 667 struct loop_device *l; 668 669 if (f->f_mapping->host->i_bdev == bdev) 670 return -EBADF; 671 672 l = f->f_mapping->host->i_bdev->bd_disk->private_data; 673 if (l->lo_state != Lo_bound) { 674 return -EINVAL; 675 } 676 f = l->lo_backing_file; 677 } 678 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 679 return -EINVAL; 680 return 0; 681} 682 683/* 684 * loop_change_fd switched the backing store of a loopback device to 685 * a new file. This is useful for operating system installers to free up 686 * the original file and in High Availability environments to switch to 687 * an alternative location for the content in case of server meltdown. 688 * This can only work if the loop device is used read-only, and if the 689 * new backing store is the same size and type as the old backing store. 690 */ 691static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 692 unsigned int arg) 693{ 694 struct file *file = NULL, *old_file; 695 int error; 696 bool partscan; 697 698 error = mutex_lock_killable(&loop_ctl_mutex); 699 if (error) 700 return error; 701 error = -ENXIO; 702 if (lo->lo_state != Lo_bound) 703 goto out_err; 704 705 /* the loop device has to be read-only */ 706 error = -EINVAL; 707 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) 708 goto out_err; 709 710 error = -EBADF; 711 file = fget(arg); 712 if (!file) 713 goto out_err; 714 715 error = loop_validate_file(file, bdev); 716 if (error) 717 goto out_err; 718 719 old_file = lo->lo_backing_file; 720 721 error = -EINVAL; 722 723 /* size of the new backing store needs to be the same */ 724 if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) 725 goto out_err; 726 727 /* and ... switch */ 728 blk_mq_freeze_queue(lo->lo_queue); 729 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); 730 lo->lo_backing_file = file; 731 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping); 732 mapping_set_gfp_mask(file->f_mapping, 733 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 734 loop_update_dio(lo); 735 blk_mq_unfreeze_queue(lo->lo_queue); 736 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; 737 mutex_unlock(&loop_ctl_mutex); 738 /* 739 * We must drop file reference outside of loop_ctl_mutex as dropping 740 * the file ref can take bd_mutex which creates circular locking 741 * dependency. 742 */ 743 fput(old_file); 744 if (partscan) 745 loop_reread_partitions(lo, bdev); 746 return 0; 747 748out_err: 749 mutex_unlock(&loop_ctl_mutex); 750 if (file) 751 fput(file); 752 return error; 753} 754 755/* loop sysfs attributes */ 756 757static ssize_t loop_attr_show(struct device *dev, char *page, 758 ssize_t (*callback)(struct loop_device *, char *)) 759{ 760 struct gendisk *disk = dev_to_disk(dev); 761 struct loop_device *lo = disk->private_data; 762 763 return callback(lo, page); 764} 765 766#define LOOP_ATTR_RO(_name) \ 767static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ 768static ssize_t loop_attr_do_show_##_name(struct device *d, \ 769 struct device_attribute *attr, char *b) \ 770{ \ 771 return loop_attr_show(d, b, loop_attr_##_name##_show); \ 772} \ 773static struct device_attribute loop_attr_##_name = \ 774 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL); 775 776static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) 777{ 778 ssize_t ret; 779 char *p = NULL; 780 781 spin_lock_irq(&lo->lo_lock); 782 if (lo->lo_backing_file) 783 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); 784 spin_unlock_irq(&lo->lo_lock); 785 786 if (IS_ERR_OR_NULL(p)) 787 ret = PTR_ERR(p); 788 else { 789 ret = strlen(p); 790 memmove(buf, p, ret); 791 buf[ret++] = '\n'; 792 buf[ret] = 0; 793 } 794 795 return ret; 796} 797 798static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) 799{ 800 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset); 801} 802 803static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) 804{ 805 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); 806} 807 808static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 809{ 810 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); 811 812 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0"); 813} 814 815static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) 816{ 817 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); 818 819 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0"); 820} 821 822static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) 823{ 824 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); 825 826 return sysfs_emit(buf, "%s\n", dio ? "1" : "0"); 827} 828 829LOOP_ATTR_RO(backing_file); 830LOOP_ATTR_RO(offset); 831LOOP_ATTR_RO(sizelimit); 832LOOP_ATTR_RO(autoclear); 833LOOP_ATTR_RO(partscan); 834LOOP_ATTR_RO(dio); 835 836static struct attribute *loop_attrs[] = { 837 &loop_attr_backing_file.attr, 838 &loop_attr_offset.attr, 839 &loop_attr_sizelimit.attr, 840 &loop_attr_autoclear.attr, 841 &loop_attr_partscan.attr, 842 &loop_attr_dio.attr, 843 NULL, 844}; 845 846static struct attribute_group loop_attribute_group = { 847 .name = "loop", 848 .attrs= loop_attrs, 849}; 850 851static void loop_sysfs_init(struct loop_device *lo) 852{ 853 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, 854 &loop_attribute_group); 855} 856 857static void loop_sysfs_exit(struct loop_device *lo) 858{ 859 if (lo->sysfs_inited) 860 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, 861 &loop_attribute_group); 862} 863 864static void loop_config_discard(struct loop_device *lo) 865{ 866 struct file *file = lo->lo_backing_file; 867 struct inode *inode = file->f_mapping->host; 868 struct request_queue *q = lo->lo_queue; 869 u32 granularity, max_discard_sectors; 870 871 /* 872 * If the backing device is a block device, mirror its zeroing 873 * capability. Set the discard sectors to the block device's zeroing 874 * capabilities because loop discards result in blkdev_issue_zeroout(), 875 * not blkdev_issue_discard(). This maintains consistent behavior with 876 * file-backed loop devices: discarded regions read back as zero. 877 */ 878 if (S_ISBLK(inode->i_mode) && !lo->lo_encrypt_key_size) { 879 struct request_queue *backingq; 880 881 backingq = bdev_get_queue(inode->i_bdev); 882 883 max_discard_sectors = backingq->limits.max_write_zeroes_sectors; 884 granularity = backingq->limits.discard_granularity ?: 885 queue_physical_block_size(backingq); 886 887 /* 888 * We use punch hole to reclaim the free space used by the 889 * image a.k.a. discard. However we do not support discard if 890 * encryption is enabled, because it may give an attacker 891 * useful information. 892 */ 893 } else if (!file->f_op->fallocate || lo->lo_encrypt_key_size) { 894 max_discard_sectors = 0; 895 granularity = 0; 896 897 } else { 898 max_discard_sectors = UINT_MAX >> 9; 899 granularity = inode->i_sb->s_blocksize; 900 } 901 902 if (max_discard_sectors) { 903 q->limits.discard_granularity = granularity; 904 blk_queue_max_discard_sectors(q, max_discard_sectors); 905 blk_queue_max_write_zeroes_sectors(q, max_discard_sectors); 906 blk_queue_flag_set(QUEUE_FLAG_DISCARD, q); 907 } else { 908 q->limits.discard_granularity = 0; 909 blk_queue_max_discard_sectors(q, 0); 910 blk_queue_max_write_zeroes_sectors(q, 0); 911 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q); 912 } 913 q->limits.discard_alignment = 0; 914} 915 916static void loop_unprepare_queue(struct loop_device *lo) 917{ 918 kthread_flush_worker(&lo->worker); 919 kthread_stop(lo->worker_task); 920} 921 922static int loop_kthread_worker_fn(void *worker_ptr) 923{ 924 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; 925 return kthread_worker_fn(worker_ptr); 926} 927 928static int loop_prepare_queue(struct loop_device *lo) 929{ 930 kthread_init_worker(&lo->worker); 931 lo->worker_task = kthread_run(loop_kthread_worker_fn, 932 &lo->worker, "loop%d", lo->lo_number); 933 if (IS_ERR(lo->worker_task)) 934 return -ENOMEM; 935 set_user_nice(lo->worker_task, MIN_NICE); 936 return 0; 937} 938 939static void loop_update_rotational(struct loop_device *lo) 940{ 941 struct file *file = lo->lo_backing_file; 942 struct inode *file_inode = file->f_mapping->host; 943 struct block_device *file_bdev = file_inode->i_sb->s_bdev; 944 struct request_queue *q = lo->lo_queue; 945 bool nonrot = true; 946 947 /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */ 948 if (file_bdev) 949 nonrot = blk_queue_nonrot(bdev_get_queue(file_bdev)); 950 951 if (nonrot) 952 blk_queue_flag_set(QUEUE_FLAG_NONROT, q); 953 else 954 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q); 955} 956 957static int 958loop_release_xfer(struct loop_device *lo) 959{ 960 int err = 0; 961 struct loop_func_table *xfer = lo->lo_encryption; 962 963 if (xfer) { 964 if (xfer->release) 965 err = xfer->release(lo); 966 lo->transfer = NULL; 967 lo->lo_encryption = NULL; 968 module_put(xfer->owner); 969 } 970 return err; 971} 972 973static int 974loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer, 975 const struct loop_info64 *i) 976{ 977 int err = 0; 978 979 if (xfer) { 980 struct module *owner = xfer->owner; 981 982 if (!try_module_get(owner)) 983 return -EINVAL; 984 if (xfer->init) 985 err = xfer->init(lo, i); 986 if (err) 987 module_put(owner); 988 else 989 lo->lo_encryption = xfer; 990 } 991 return err; 992} 993 994/** 995 * loop_set_status_from_info - configure device from loop_info 996 * @lo: struct loop_device to configure 997 * @info: struct loop_info64 to configure the device with 998 * 999 * Configures the loop device parameters according to the passed 1000 * in loop_info64 configuration. 1001 */ 1002static int 1003loop_set_status_from_info(struct loop_device *lo, 1004 const struct loop_info64 *info) 1005{ 1006 int err; 1007 struct loop_func_table *xfer; 1008 kuid_t uid = current_uid(); 1009 1010 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) 1011 return -EINVAL; 1012 1013 err = loop_release_xfer(lo); 1014 if (err) 1015 return err; 1016 1017 if (info->lo_encrypt_type) { 1018 unsigned int type = info->lo_encrypt_type; 1019 1020 if (type >= MAX_LO_CRYPT) 1021 return -EINVAL; 1022 xfer = xfer_funcs[type]; 1023 if (xfer == NULL) 1024 return -EINVAL; 1025 } else 1026 xfer = NULL; 1027 1028 err = loop_init_xfer(lo, xfer, info); 1029 if (err) 1030 return err; 1031 1032 /* Avoid assigning overflow values */ 1033 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX) 1034 return -EOVERFLOW; 1035 1036 lo->lo_offset = info->lo_offset; 1037 lo->lo_sizelimit = info->lo_sizelimit; 1038 1039 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); 1040 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); 1041 lo->lo_file_name[LO_NAME_SIZE-1] = 0; 1042 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0; 1043 1044 if (!xfer) 1045 xfer = &none_funcs; 1046 lo->transfer = xfer->transfer; 1047 lo->ioctl = xfer->ioctl; 1048 1049 lo->lo_flags = info->lo_flags; 1050 1051 lo->lo_encrypt_key_size = info->lo_encrypt_key_size; 1052 lo->lo_init[0] = info->lo_init[0]; 1053 lo->lo_init[1] = info->lo_init[1]; 1054 if (info->lo_encrypt_key_size) { 1055 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key, 1056 info->lo_encrypt_key_size); 1057 lo->lo_key_owner = uid; 1058 } 1059 1060 return 0; 1061} 1062 1063static int loop_configure(struct loop_device *lo, fmode_t mode, 1064 struct block_device *bdev, 1065 const struct loop_config *config) 1066{ 1067 struct file *file; 1068 struct inode *inode; 1069 struct address_space *mapping; 1070 struct block_device *claimed_bdev = NULL; 1071 int error; 1072 loff_t size; 1073 bool partscan; 1074 unsigned short bsize; 1075 1076 /* This is safe, since we have a reference from open(). */ 1077 __module_get(THIS_MODULE); 1078 1079 error = -EBADF; 1080 file = fget(config->fd); 1081 if (!file) 1082 goto out; 1083 1084 /* 1085 * If we don't hold exclusive handle for the device, upgrade to it 1086 * here to avoid changing device under exclusive owner. 1087 */ 1088 if (!(mode & FMODE_EXCL)) { 1089 claimed_bdev = bdev->bd_contains; 1090 error = bd_prepare_to_claim(bdev, claimed_bdev, loop_configure); 1091 if (error) 1092 goto out_putf; 1093 } 1094 1095 error = mutex_lock_killable(&loop_ctl_mutex); 1096 if (error) 1097 goto out_bdev; 1098 1099 error = -EBUSY; 1100 if (lo->lo_state != Lo_unbound) 1101 goto out_unlock; 1102 1103 error = loop_validate_file(file, bdev); 1104 if (error) 1105 goto out_unlock; 1106 1107 mapping = file->f_mapping; 1108 inode = mapping->host; 1109 1110 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { 1111 error = -EINVAL; 1112 goto out_unlock; 1113 } 1114 1115 if (config->block_size) { 1116 error = blk_validate_block_size(config->block_size); 1117 if (error) 1118 goto out_unlock; 1119 } 1120 1121 error = loop_set_status_from_info(lo, &config->info); 1122 if (error) 1123 goto out_unlock; 1124 1125 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || 1126 !file->f_op->write_iter) 1127 lo->lo_flags |= LO_FLAGS_READ_ONLY; 1128 1129 error = loop_prepare_queue(lo); 1130 if (error) 1131 goto out_unlock; 1132 1133 set_device_ro(bdev, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); 1134 1135 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO; 1136 lo->lo_device = bdev; 1137 lo->lo_backing_file = file; 1138 lo->old_gfp_mask = mapping_gfp_mask(mapping); 1139 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 1140 1141 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) 1142 blk_queue_write_cache(lo->lo_queue, true, false); 1143 1144 if (config->block_size) 1145 bsize = config->block_size; 1146 else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev) 1147 /* In case of direct I/O, match underlying block size */ 1148 bsize = bdev_logical_block_size(inode->i_sb->s_bdev); 1149 else 1150 bsize = 512; 1151 1152 blk_queue_logical_block_size(lo->lo_queue, bsize); 1153 blk_queue_physical_block_size(lo->lo_queue, bsize); 1154 blk_queue_io_min(lo->lo_queue, bsize); 1155 1156 loop_config_discard(lo); 1157 loop_update_rotational(lo); 1158 loop_update_dio(lo); 1159 loop_sysfs_init(lo); 1160 1161 size = get_loop_size(lo, file); 1162 loop_set_size(lo, size); 1163 1164 set_blocksize(bdev, S_ISBLK(inode->i_mode) ? 1165 block_size(inode->i_bdev) : PAGE_SIZE); 1166 1167 lo->lo_state = Lo_bound; 1168 if (part_shift) 1169 lo->lo_flags |= LO_FLAGS_PARTSCAN; 1170 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; 1171 if (partscan) 1172 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; 1173 1174 /* Grab the block_device to prevent its destruction after we 1175 * put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev). 1176 */ 1177 bdgrab(bdev); 1178 mutex_unlock(&loop_ctl_mutex); 1179 if (partscan) 1180 loop_reread_partitions(lo, bdev); 1181 if (claimed_bdev) 1182 bd_abort_claiming(bdev, claimed_bdev, loop_configure); 1183 return 0; 1184 1185out_unlock: 1186 mutex_unlock(&loop_ctl_mutex); 1187out_bdev: 1188 if (claimed_bdev) 1189 bd_abort_claiming(bdev, claimed_bdev, loop_configure); 1190out_putf: 1191 fput(file); 1192out: 1193 /* This is safe: open() is still holding a reference. */ 1194 module_put(THIS_MODULE); 1195 return error; 1196} 1197 1198static int __loop_clr_fd(struct loop_device *lo, bool release) 1199{ 1200 struct file *filp = NULL; 1201 gfp_t gfp = lo->old_gfp_mask; 1202 struct block_device *bdev = lo->lo_device; 1203 int err = 0; 1204 bool partscan = false; 1205 int lo_number; 1206 1207 mutex_lock(&loop_ctl_mutex); 1208 if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) { 1209 err = -ENXIO; 1210 goto out_unlock; 1211 } 1212 1213 filp = lo->lo_backing_file; 1214 if (filp == NULL) { 1215 err = -EINVAL; 1216 goto out_unlock; 1217 } 1218 1219 if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags)) 1220 blk_queue_write_cache(lo->lo_queue, false, false); 1221 1222 /* freeze request queue during the transition */ 1223 blk_mq_freeze_queue(lo->lo_queue); 1224 1225 spin_lock_irq(&lo->lo_lock); 1226 lo->lo_backing_file = NULL; 1227 spin_unlock_irq(&lo->lo_lock); 1228 1229 loop_release_xfer(lo); 1230 lo->transfer = NULL; 1231 lo->ioctl = NULL; 1232 lo->lo_device = NULL; 1233 lo->lo_encryption = NULL; 1234 lo->lo_offset = 0; 1235 lo->lo_sizelimit = 0; 1236 lo->lo_encrypt_key_size = 0; 1237 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE); 1238 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE); 1239 memset(lo->lo_file_name, 0, LO_NAME_SIZE); 1240 blk_queue_logical_block_size(lo->lo_queue, 512); 1241 blk_queue_physical_block_size(lo->lo_queue, 512); 1242 blk_queue_io_min(lo->lo_queue, 512); 1243 if (bdev) { 1244 bdput(bdev); 1245 invalidate_bdev(bdev); 1246 bdev->bd_inode->i_mapping->wb_err = 0; 1247 } 1248 set_capacity(lo->lo_disk, 0); 1249 loop_sysfs_exit(lo); 1250 if (bdev) { 1251 bd_set_nr_sectors(bdev, 0); 1252 /* let user-space know about this change */ 1253 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE); 1254 } 1255 mapping_set_gfp_mask(filp->f_mapping, gfp); 1256 /* This is safe: open() is still holding a reference. */ 1257 module_put(THIS_MODULE); 1258 blk_mq_unfreeze_queue(lo->lo_queue); 1259 1260 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev; 1261 lo_number = lo->lo_number; 1262 loop_unprepare_queue(lo); 1263out_unlock: 1264 mutex_unlock(&loop_ctl_mutex); 1265 if (partscan) { 1266 /* 1267 * bd_mutex has been held already in release path, so don't 1268 * acquire it if this function is called in such case. 1269 * 1270 * If the reread partition isn't from release path, lo_refcnt 1271 * must be at least one and it can only become zero when the 1272 * current holder is released. 1273 */ 1274 if (!release) 1275 mutex_lock(&bdev->bd_mutex); 1276 err = bdev_disk_changed(bdev, false); 1277 if (!release) 1278 mutex_unlock(&bdev->bd_mutex); 1279 if (err) 1280 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", 1281 __func__, lo_number, err); 1282 /* Device is gone, no point in returning error */ 1283 err = 0; 1284 } 1285 1286 /* 1287 * lo->lo_state is set to Lo_unbound here after above partscan has 1288 * finished. 1289 * 1290 * There cannot be anybody else entering __loop_clr_fd() as 1291 * lo->lo_backing_file is already cleared and Lo_rundown state 1292 * protects us from all the other places trying to change the 'lo' 1293 * device. 1294 */ 1295 mutex_lock(&loop_ctl_mutex); 1296 lo->lo_flags = 0; 1297 if (!part_shift) 1298 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN; 1299 lo->lo_state = Lo_unbound; 1300 mutex_unlock(&loop_ctl_mutex); 1301 1302 /* 1303 * Need not hold loop_ctl_mutex to fput backing file. 1304 * Calling fput holding loop_ctl_mutex triggers a circular 1305 * lock dependency possibility warning as fput can take 1306 * bd_mutex which is usually taken before loop_ctl_mutex. 1307 */ 1308 if (filp) 1309 fput(filp); 1310 return err; 1311} 1312 1313static int loop_clr_fd(struct loop_device *lo) 1314{ 1315 int err; 1316 1317 err = mutex_lock_killable(&loop_ctl_mutex); 1318 if (err) 1319 return err; 1320 if (lo->lo_state != Lo_bound) { 1321 mutex_unlock(&loop_ctl_mutex); 1322 return -ENXIO; 1323 } 1324 /* 1325 * If we've explicitly asked to tear down the loop device, 1326 * and it has an elevated reference count, set it for auto-teardown when 1327 * the last reference goes away. This stops $!~#$@ udev from 1328 * preventing teardown because it decided that it needs to run blkid on 1329 * the loopback device whenever they appear. xfstests is notorious for 1330 * failing tests because blkid via udev races with a losetup 1331 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d 1332 * command to fail with EBUSY. 1333 */ 1334 if (atomic_read(&lo->lo_refcnt) > 1) { 1335 lo->lo_flags |= LO_FLAGS_AUTOCLEAR; 1336 mutex_unlock(&loop_ctl_mutex); 1337 return 0; 1338 } 1339 lo->lo_state = Lo_rundown; 1340 mutex_unlock(&loop_ctl_mutex); 1341 1342 return __loop_clr_fd(lo, false); 1343} 1344 1345static int 1346loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 1347{ 1348 int err; 1349 struct block_device *bdev; 1350 kuid_t uid = current_uid(); 1351 int prev_lo_flags; 1352 bool partscan = false; 1353 bool size_changed = false; 1354 1355 err = mutex_lock_killable(&loop_ctl_mutex); 1356 if (err) 1357 return err; 1358 if (lo->lo_encrypt_key_size && 1359 !uid_eq(lo->lo_key_owner, uid) && 1360 !capable(CAP_SYS_ADMIN)) { 1361 err = -EPERM; 1362 goto out_unlock; 1363 } 1364 if (lo->lo_state != Lo_bound) { 1365 err = -ENXIO; 1366 goto out_unlock; 1367 } 1368 1369 if (lo->lo_offset != info->lo_offset || 1370 lo->lo_sizelimit != info->lo_sizelimit) { 1371 size_changed = true; 1372 sync_blockdev(lo->lo_device); 1373 invalidate_bdev(lo->lo_device); 1374 } 1375 1376 /* I/O need to be drained during transfer transition */ 1377 blk_mq_freeze_queue(lo->lo_queue); 1378 1379 if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) { 1380 /* If any pages were dirtied after invalidate_bdev(), try again */ 1381 err = -EAGAIN; 1382 pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", 1383 __func__, lo->lo_number, lo->lo_file_name, 1384 lo->lo_device->bd_inode->i_mapping->nrpages); 1385 goto out_unfreeze; 1386 } 1387 1388 prev_lo_flags = lo->lo_flags; 1389 1390 err = loop_set_status_from_info(lo, info); 1391 if (err) 1392 goto out_unfreeze; 1393 1394 /* Mask out flags that can't be set using LOOP_SET_STATUS. */ 1395 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS; 1396 /* For those flags, use the previous values instead */ 1397 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS; 1398 /* For flags that can't be cleared, use previous values too */ 1399 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS; 1400 1401 if (size_changed) { 1402 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit, 1403 lo->lo_backing_file); 1404 loop_set_size(lo, new_size); 1405 } 1406 1407 loop_config_discard(lo); 1408 1409 /* update dio if lo_offset or transfer is changed */ 1410 __loop_update_dio(lo, lo->use_dio); 1411 1412out_unfreeze: 1413 blk_mq_unfreeze_queue(lo->lo_queue); 1414 1415 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && 1416 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { 1417 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN; 1418 bdev = lo->lo_device; 1419 partscan = true; 1420 } 1421out_unlock: 1422 mutex_unlock(&loop_ctl_mutex); 1423 if (partscan) 1424 loop_reread_partitions(lo, bdev); 1425 1426 return err; 1427} 1428 1429static int 1430loop_get_status(struct loop_device *lo, struct loop_info64 *info) 1431{ 1432 struct path path; 1433 struct kstat stat; 1434 int ret; 1435 1436 ret = mutex_lock_killable(&loop_ctl_mutex); 1437 if (ret) 1438 return ret; 1439 if (lo->lo_state != Lo_bound) { 1440 mutex_unlock(&loop_ctl_mutex); 1441 return -ENXIO; 1442 } 1443 1444 memset(info, 0, sizeof(*info)); 1445 info->lo_number = lo->lo_number; 1446 info->lo_offset = lo->lo_offset; 1447 info->lo_sizelimit = lo->lo_sizelimit; 1448 info->lo_flags = lo->lo_flags; 1449 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); 1450 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE); 1451 info->lo_encrypt_type = 1452 lo->lo_encryption ? lo->lo_encryption->number : 0; 1453 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) { 1454 info->lo_encrypt_key_size = lo->lo_encrypt_key_size; 1455 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key, 1456 lo->lo_encrypt_key_size); 1457 } 1458 1459 /* Drop loop_ctl_mutex while we call into the filesystem. */ 1460 path = lo->lo_backing_file->f_path; 1461 path_get(&path); 1462 mutex_unlock(&loop_ctl_mutex); 1463 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT); 1464 if (!ret) { 1465 info->lo_device = huge_encode_dev(stat.dev); 1466 info->lo_inode = stat.ino; 1467 info->lo_rdevice = huge_encode_dev(stat.rdev); 1468 } 1469 path_put(&path); 1470 return ret; 1471} 1472 1473static void 1474loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) 1475{ 1476 memset(info64, 0, sizeof(*info64)); 1477 info64->lo_number = info->lo_number; 1478 info64->lo_device = info->lo_device; 1479 info64->lo_inode = info->lo_inode; 1480 info64->lo_rdevice = info->lo_rdevice; 1481 info64->lo_offset = info->lo_offset; 1482 info64->lo_sizelimit = 0; 1483 info64->lo_encrypt_type = info->lo_encrypt_type; 1484 info64->lo_encrypt_key_size = info->lo_encrypt_key_size; 1485 info64->lo_flags = info->lo_flags; 1486 info64->lo_init[0] = info->lo_init[0]; 1487 info64->lo_init[1] = info->lo_init[1]; 1488 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1489 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE); 1490 else 1491 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); 1492 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE); 1493} 1494 1495static int 1496loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) 1497{ 1498 memset(info, 0, sizeof(*info)); 1499 info->lo_number = info64->lo_number; 1500 info->lo_device = info64->lo_device; 1501 info->lo_inode = info64->lo_inode; 1502 info->lo_rdevice = info64->lo_rdevice; 1503 info->lo_offset = info64->lo_offset; 1504 info->lo_encrypt_type = info64->lo_encrypt_type; 1505 info->lo_encrypt_key_size = info64->lo_encrypt_key_size; 1506 info->lo_flags = info64->lo_flags; 1507 info->lo_init[0] = info64->lo_init[0]; 1508 info->lo_init[1] = info64->lo_init[1]; 1509 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1510 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1511 else 1512 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); 1513 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1514 1515 /* error in case values were truncated */ 1516 if (info->lo_device != info64->lo_device || 1517 info->lo_rdevice != info64->lo_rdevice || 1518 info->lo_inode != info64->lo_inode || 1519 info->lo_offset != info64->lo_offset) 1520 return -EOVERFLOW; 1521 1522 return 0; 1523} 1524 1525static int 1526loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) 1527{ 1528 struct loop_info info; 1529 struct loop_info64 info64; 1530 1531 if (copy_from_user(&info, arg, sizeof (struct loop_info))) 1532 return -EFAULT; 1533 loop_info64_from_old(&info, &info64); 1534 return loop_set_status(lo, &info64); 1535} 1536 1537static int 1538loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) 1539{ 1540 struct loop_info64 info64; 1541 1542 if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) 1543 return -EFAULT; 1544 return loop_set_status(lo, &info64); 1545} 1546 1547static int 1548loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { 1549 struct loop_info info; 1550 struct loop_info64 info64; 1551 int err; 1552 1553 if (!arg) 1554 return -EINVAL; 1555 err = loop_get_status(lo, &info64); 1556 if (!err) 1557 err = loop_info64_to_old(&info64, &info); 1558 if (!err && copy_to_user(arg, &info, sizeof(info))) 1559 err = -EFAULT; 1560 1561 return err; 1562} 1563 1564static int 1565loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { 1566 struct loop_info64 info64; 1567 int err; 1568 1569 if (!arg) 1570 return -EINVAL; 1571 err = loop_get_status(lo, &info64); 1572 if (!err && copy_to_user(arg, &info64, sizeof(info64))) 1573 err = -EFAULT; 1574 1575 return err; 1576} 1577 1578static int loop_set_capacity(struct loop_device *lo) 1579{ 1580 loff_t size; 1581 1582 if (unlikely(lo->lo_state != Lo_bound)) 1583 return -ENXIO; 1584 1585 size = get_loop_size(lo, lo->lo_backing_file); 1586 loop_set_size(lo, size); 1587 1588 return 0; 1589} 1590 1591static int loop_set_dio(struct loop_device *lo, unsigned long arg) 1592{ 1593 int error = -ENXIO; 1594 if (lo->lo_state != Lo_bound) 1595 goto out; 1596 1597 __loop_update_dio(lo, !!arg); 1598 if (lo->use_dio == !!arg) 1599 return 0; 1600 error = -EINVAL; 1601 out: 1602 return error; 1603} 1604 1605static int loop_set_block_size(struct loop_device *lo, unsigned long arg) 1606{ 1607 int err = 0; 1608 1609 if (lo->lo_state != Lo_bound) 1610 return -ENXIO; 1611 1612 err = blk_validate_block_size(arg); 1613 if (err) 1614 return err; 1615 1616 if (lo->lo_queue->limits.logical_block_size == arg) 1617 return 0; 1618 1619 sync_blockdev(lo->lo_device); 1620 invalidate_bdev(lo->lo_device); 1621 1622 blk_mq_freeze_queue(lo->lo_queue); 1623 1624 /* invalidate_bdev should have truncated all the pages */ 1625 if (lo->lo_device->bd_inode->i_mapping->nrpages) { 1626 err = -EAGAIN; 1627 pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n", 1628 __func__, lo->lo_number, lo->lo_file_name, 1629 lo->lo_device->bd_inode->i_mapping->nrpages); 1630 goto out_unfreeze; 1631 } 1632 1633 blk_queue_logical_block_size(lo->lo_queue, arg); 1634 blk_queue_physical_block_size(lo->lo_queue, arg); 1635 blk_queue_io_min(lo->lo_queue, arg); 1636 loop_update_dio(lo); 1637out_unfreeze: 1638 blk_mq_unfreeze_queue(lo->lo_queue); 1639 1640 return err; 1641} 1642 1643static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd, 1644 unsigned long arg) 1645{ 1646 int err; 1647 1648 err = mutex_lock_killable(&loop_ctl_mutex); 1649 if (err) 1650 return err; 1651 switch (cmd) { 1652 case LOOP_SET_CAPACITY: 1653 err = loop_set_capacity(lo); 1654 break; 1655 case LOOP_SET_DIRECT_IO: 1656 err = loop_set_dio(lo, arg); 1657 break; 1658 case LOOP_SET_BLOCK_SIZE: 1659 err = loop_set_block_size(lo, arg); 1660 break; 1661 default: 1662 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL; 1663 } 1664 mutex_unlock(&loop_ctl_mutex); 1665 return err; 1666} 1667 1668static int lo_ioctl(struct block_device *bdev, fmode_t mode, 1669 unsigned int cmd, unsigned long arg) 1670{ 1671 struct loop_device *lo = bdev->bd_disk->private_data; 1672 void __user *argp = (void __user *) arg; 1673 int err; 1674 1675 switch (cmd) { 1676 case LOOP_SET_FD: { 1677 /* 1678 * Legacy case - pass in a zeroed out struct loop_config with 1679 * only the file descriptor set , which corresponds with the 1680 * default parameters we'd have used otherwise. 1681 */ 1682 struct loop_config config; 1683 1684 memset(&config, 0, sizeof(config)); 1685 config.fd = arg; 1686 1687 return loop_configure(lo, mode, bdev, &config); 1688 } 1689 case LOOP_CONFIGURE: { 1690 struct loop_config config; 1691 1692 if (copy_from_user(&config, argp, sizeof(config))) 1693 return -EFAULT; 1694 1695 return loop_configure(lo, mode, bdev, &config); 1696 } 1697 case LOOP_CHANGE_FD: 1698 return loop_change_fd(lo, bdev, arg); 1699 case LOOP_CLR_FD: 1700 return loop_clr_fd(lo); 1701 case LOOP_SET_STATUS: 1702 err = -EPERM; 1703 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) { 1704 err = loop_set_status_old(lo, argp); 1705 } 1706 break; 1707 case LOOP_GET_STATUS: 1708 return loop_get_status_old(lo, argp); 1709 case LOOP_SET_STATUS64: 1710 err = -EPERM; 1711 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) { 1712 err = loop_set_status64(lo, argp); 1713 } 1714 break; 1715 case LOOP_GET_STATUS64: 1716 return loop_get_status64(lo, argp); 1717 case LOOP_SET_CAPACITY: 1718 case LOOP_SET_DIRECT_IO: 1719 case LOOP_SET_BLOCK_SIZE: 1720 if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN)) 1721 return -EPERM; 1722 fallthrough; 1723 default: 1724 err = lo_simple_ioctl(lo, cmd, arg); 1725 break; 1726 } 1727 1728 return err; 1729} 1730 1731#ifdef CONFIG_COMPAT 1732struct compat_loop_info { 1733 compat_int_t lo_number; /* ioctl r/o */ 1734 compat_dev_t lo_device; /* ioctl r/o */ 1735 compat_ulong_t lo_inode; /* ioctl r/o */ 1736 compat_dev_t lo_rdevice; /* ioctl r/o */ 1737 compat_int_t lo_offset; 1738 compat_int_t lo_encrypt_type; 1739 compat_int_t lo_encrypt_key_size; /* ioctl w/o */ 1740 compat_int_t lo_flags; /* ioctl r/o */ 1741 char lo_name[LO_NAME_SIZE]; 1742 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ 1743 compat_ulong_t lo_init[2]; 1744 char reserved[4]; 1745}; 1746 1747/* 1748 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info 1749 * - noinlined to reduce stack space usage in main part of driver 1750 */ 1751static noinline int 1752loop_info64_from_compat(const struct compat_loop_info __user *arg, 1753 struct loop_info64 *info64) 1754{ 1755 struct compat_loop_info info; 1756 1757 if (copy_from_user(&info, arg, sizeof(info))) 1758 return -EFAULT; 1759 1760 memset(info64, 0, sizeof(*info64)); 1761 info64->lo_number = info.lo_number; 1762 info64->lo_device = info.lo_device; 1763 info64->lo_inode = info.lo_inode; 1764 info64->lo_rdevice = info.lo_rdevice; 1765 info64->lo_offset = info.lo_offset; 1766 info64->lo_sizelimit = 0; 1767 info64->lo_encrypt_type = info.lo_encrypt_type; 1768 info64->lo_encrypt_key_size = info.lo_encrypt_key_size; 1769 info64->lo_flags = info.lo_flags; 1770 info64->lo_init[0] = info.lo_init[0]; 1771 info64->lo_init[1] = info.lo_init[1]; 1772 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1773 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE); 1774 else 1775 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); 1776 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE); 1777 return 0; 1778} 1779 1780/* 1781 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace 1782 * - noinlined to reduce stack space usage in main part of driver 1783 */ 1784static noinline int 1785loop_info64_to_compat(const struct loop_info64 *info64, 1786 struct compat_loop_info __user *arg) 1787{ 1788 struct compat_loop_info info; 1789 1790 memset(&info, 0, sizeof(info)); 1791 info.lo_number = info64->lo_number; 1792 info.lo_device = info64->lo_device; 1793 info.lo_inode = info64->lo_inode; 1794 info.lo_rdevice = info64->lo_rdevice; 1795 info.lo_offset = info64->lo_offset; 1796 info.lo_encrypt_type = info64->lo_encrypt_type; 1797 info.lo_encrypt_key_size = info64->lo_encrypt_key_size; 1798 info.lo_flags = info64->lo_flags; 1799 info.lo_init[0] = info64->lo_init[0]; 1800 info.lo_init[1] = info64->lo_init[1]; 1801 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI) 1802 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE); 1803 else 1804 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); 1805 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE); 1806 1807 /* error in case values were truncated */ 1808 if (info.lo_device != info64->lo_device || 1809 info.lo_rdevice != info64->lo_rdevice || 1810 info.lo_inode != info64->lo_inode || 1811 info.lo_offset != info64->lo_offset || 1812 info.lo_init[0] != info64->lo_init[0] || 1813 info.lo_init[1] != info64->lo_init[1]) 1814 return -EOVERFLOW; 1815 1816 if (copy_to_user(arg, &info, sizeof(info))) 1817 return -EFAULT; 1818 return 0; 1819} 1820 1821static int 1822loop_set_status_compat(struct loop_device *lo, 1823 const struct compat_loop_info __user *arg) 1824{ 1825 struct loop_info64 info64; 1826 int ret; 1827 1828 ret = loop_info64_from_compat(arg, &info64); 1829 if (ret < 0) 1830 return ret; 1831 return loop_set_status(lo, &info64); 1832} 1833 1834static int 1835loop_get_status_compat(struct loop_device *lo, 1836 struct compat_loop_info __user *arg) 1837{ 1838 struct loop_info64 info64; 1839 int err; 1840 1841 if (!arg) 1842 return -EINVAL; 1843 err = loop_get_status(lo, &info64); 1844 if (!err) 1845 err = loop_info64_to_compat(&info64, arg); 1846 return err; 1847} 1848 1849static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode, 1850 unsigned int cmd, unsigned long arg) 1851{ 1852 struct loop_device *lo = bdev->bd_disk->private_data; 1853 int err; 1854 1855 switch(cmd) { 1856 case LOOP_SET_STATUS: 1857 err = loop_set_status_compat(lo, 1858 (const struct compat_loop_info __user *)arg); 1859 break; 1860 case LOOP_GET_STATUS: 1861 err = loop_get_status_compat(lo, 1862 (struct compat_loop_info __user *)arg); 1863 break; 1864 case LOOP_SET_CAPACITY: 1865 case LOOP_CLR_FD: 1866 case LOOP_GET_STATUS64: 1867 case LOOP_SET_STATUS64: 1868 case LOOP_CONFIGURE: 1869 arg = (unsigned long) compat_ptr(arg); 1870 fallthrough; 1871 case LOOP_SET_FD: 1872 case LOOP_CHANGE_FD: 1873 case LOOP_SET_BLOCK_SIZE: 1874 case LOOP_SET_DIRECT_IO: 1875 err = lo_ioctl(bdev, mode, cmd, arg); 1876 break; 1877 default: 1878 err = -ENOIOCTLCMD; 1879 break; 1880 } 1881 return err; 1882} 1883#endif 1884 1885static int lo_open(struct block_device *bdev, fmode_t mode) 1886{ 1887 struct loop_device *lo; 1888 int err; 1889 1890 err = mutex_lock_killable(&loop_ctl_mutex); 1891 if (err) 1892 return err; 1893 lo = bdev->bd_disk->private_data; 1894 if (!lo) { 1895 err = -ENXIO; 1896 goto out; 1897 } 1898 1899 atomic_inc(&lo->lo_refcnt); 1900out: 1901 mutex_unlock(&loop_ctl_mutex); 1902 return err; 1903} 1904 1905static void lo_release(struct gendisk *disk, fmode_t mode) 1906{ 1907 struct loop_device *lo; 1908 1909 mutex_lock(&loop_ctl_mutex); 1910 lo = disk->private_data; 1911 if (atomic_dec_return(&lo->lo_refcnt)) 1912 goto out_unlock; 1913 1914 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) { 1915 if (lo->lo_state != Lo_bound) 1916 goto out_unlock; 1917 lo->lo_state = Lo_rundown; 1918 mutex_unlock(&loop_ctl_mutex); 1919 /* 1920 * In autoclear mode, stop the loop thread 1921 * and remove configuration after last close. 1922 */ 1923 __loop_clr_fd(lo, true); 1924 return; 1925 } else if (lo->lo_state == Lo_bound) { 1926 /* 1927 * Otherwise keep thread (if running) and config, 1928 * but flush possible ongoing bios in thread. 1929 */ 1930 blk_mq_freeze_queue(lo->lo_queue); 1931 blk_mq_unfreeze_queue(lo->lo_queue); 1932 } 1933 1934out_unlock: 1935 mutex_unlock(&loop_ctl_mutex); 1936} 1937 1938static const struct block_device_operations lo_fops = { 1939 .owner = THIS_MODULE, 1940 .open = lo_open, 1941 .release = lo_release, 1942 .ioctl = lo_ioctl, 1943#ifdef CONFIG_COMPAT 1944 .compat_ioctl = lo_compat_ioctl, 1945#endif 1946}; 1947 1948/* 1949 * And now the modules code and kernel interface. 1950 */ 1951static int max_loop; 1952module_param(max_loop, int, 0444); 1953MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); 1954module_param(max_part, int, 0444); 1955MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); 1956MODULE_LICENSE("GPL"); 1957MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); 1958 1959int loop_register_transfer(struct loop_func_table *funcs) 1960{ 1961 unsigned int n = funcs->number; 1962 1963 if (n >= MAX_LO_CRYPT || xfer_funcs[n]) 1964 return -EINVAL; 1965 xfer_funcs[n] = funcs; 1966 return 0; 1967} 1968 1969static int unregister_transfer_cb(int id, void *ptr, void *data) 1970{ 1971 struct loop_device *lo = ptr; 1972 struct loop_func_table *xfer = data; 1973 1974 mutex_lock(&loop_ctl_mutex); 1975 if (lo->lo_encryption == xfer) 1976 loop_release_xfer(lo); 1977 mutex_unlock(&loop_ctl_mutex); 1978 return 0; 1979} 1980 1981int loop_unregister_transfer(int number) 1982{ 1983 unsigned int n = number; 1984 struct loop_func_table *xfer; 1985 1986 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL) 1987 return -EINVAL; 1988 1989 xfer_funcs[n] = NULL; 1990 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer); 1991 return 0; 1992} 1993 1994EXPORT_SYMBOL(loop_register_transfer); 1995EXPORT_SYMBOL(loop_unregister_transfer); 1996 1997static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx, 1998 const struct blk_mq_queue_data *bd) 1999{ 2000 struct request *rq = bd->rq; 2001 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 2002 struct loop_device *lo = rq->q->queuedata; 2003 2004 blk_mq_start_request(rq); 2005 2006 if (lo->lo_state != Lo_bound) 2007 return BLK_STS_IOERR; 2008 2009 switch (req_op(rq)) { 2010 case REQ_OP_FLUSH: 2011 case REQ_OP_DISCARD: 2012 case REQ_OP_WRITE_ZEROES: 2013 cmd->use_aio = false; 2014 break; 2015 default: 2016 cmd->use_aio = lo->use_dio; 2017 break; 2018 } 2019 2020 /* always use the first bio's css */ 2021#ifdef CONFIG_BLK_CGROUP 2022 if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) { 2023 cmd->css = &bio_blkcg(rq->bio)->css; 2024 css_get(cmd->css); 2025 } else 2026#endif 2027 cmd->css = NULL; 2028 kthread_queue_work(&lo->worker, &cmd->work); 2029 2030 return BLK_STS_OK; 2031} 2032 2033static void loop_handle_cmd(struct loop_cmd *cmd) 2034{ 2035 struct request *rq = blk_mq_rq_from_pdu(cmd); 2036 const bool write = op_is_write(req_op(rq)); 2037 struct loop_device *lo = rq->q->queuedata; 2038 int ret = 0; 2039 2040 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { 2041 ret = -EIO; 2042 goto failed; 2043 } 2044 2045 ret = do_req_filebacked(lo, rq); 2046 failed: 2047 /* complete non-aio request */ 2048 if (!cmd->use_aio || ret) { 2049 if (ret == -EOPNOTSUPP) 2050 cmd->ret = ret; 2051 else 2052 cmd->ret = ret ? -EIO : 0; 2053 if (likely(!blk_should_fake_timeout(rq->q))) 2054 blk_mq_complete_request(rq); 2055 } 2056} 2057 2058static void loop_queue_work(struct kthread_work *work) 2059{ 2060 struct loop_cmd *cmd = 2061 container_of(work, struct loop_cmd, work); 2062 2063 loop_handle_cmd(cmd); 2064} 2065 2066static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq, 2067 unsigned int hctx_idx, unsigned int numa_node) 2068{ 2069 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 2070 2071 kthread_init_work(&cmd->work, loop_queue_work); 2072 return 0; 2073} 2074 2075static const struct blk_mq_ops loop_mq_ops = { 2076 .queue_rq = loop_queue_rq, 2077 .init_request = loop_init_request, 2078 .complete = lo_complete_rq, 2079}; 2080 2081static int loop_add(struct loop_device **l, int i) 2082{ 2083 struct loop_device *lo; 2084 struct gendisk *disk; 2085 int err; 2086 2087 err = -ENOMEM; 2088 lo = kzalloc(sizeof(*lo), GFP_KERNEL); 2089 if (!lo) 2090 goto out; 2091 2092 lo->lo_state = Lo_unbound; 2093 2094 /* allocate id, if @id >= 0, we're requesting that specific id */ 2095 if (i >= 0) { 2096 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); 2097 if (err == -ENOSPC) 2098 err = -EEXIST; 2099 } else { 2100 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); 2101 } 2102 if (err < 0) 2103 goto out_free_dev; 2104 i = err; 2105 2106 err = -ENOMEM; 2107 lo->tag_set.ops = &loop_mq_ops; 2108 lo->tag_set.nr_hw_queues = 1; 2109 lo->tag_set.queue_depth = 128; 2110 lo->tag_set.numa_node = NUMA_NO_NODE; 2111 lo->tag_set.cmd_size = sizeof(struct loop_cmd); 2112 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING | 2113 BLK_MQ_F_NO_SCHED_BY_DEFAULT; 2114 lo->tag_set.driver_data = lo; 2115 2116 err = blk_mq_alloc_tag_set(&lo->tag_set); 2117 if (err) 2118 goto out_free_idr; 2119 2120 lo->lo_queue = blk_mq_init_queue(&lo->tag_set); 2121 if (IS_ERR(lo->lo_queue)) { 2122 err = PTR_ERR(lo->lo_queue); 2123 goto out_cleanup_tags; 2124 } 2125 lo->lo_queue->queuedata = lo; 2126 2127 blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS); 2128 2129 /* 2130 * By default, we do buffer IO, so it doesn't make sense to enable 2131 * merge because the I/O submitted to backing file is handled page by 2132 * page. For directio mode, merge does help to dispatch bigger request 2133 * to underlayer disk. We will enable merge once directio is enabled. 2134 */ 2135 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); 2136 2137 err = -ENOMEM; 2138 disk = lo->lo_disk = alloc_disk(1 << part_shift); 2139 if (!disk) 2140 goto out_free_queue; 2141 2142 /* 2143 * Disable partition scanning by default. The in-kernel partition 2144 * scanning can be requested individually per-device during its 2145 * setup. Userspace can always add and remove partitions from all 2146 * devices. The needed partition minors are allocated from the 2147 * extended minor space, the main loop device numbers will continue 2148 * to match the loop minors, regardless of the number of partitions 2149 * used. 2150 * 2151 * If max_part is given, partition scanning is globally enabled for 2152 * all loop devices. The minors for the main loop devices will be 2153 * multiples of max_part. 2154 * 2155 * Note: Global-for-all-devices, set-only-at-init, read-only module 2156 * parameteters like 'max_loop' and 'max_part' make things needlessly 2157 * complicated, are too static, inflexible and may surprise 2158 * userspace tools. Parameters like this in general should be avoided. 2159 */ 2160 if (!part_shift) 2161 disk->flags |= GENHD_FL_NO_PART_SCAN; 2162 disk->flags |= GENHD_FL_EXT_DEVT; 2163 atomic_set(&lo->lo_refcnt, 0); 2164 lo->lo_number = i; 2165 spin_lock_init(&lo->lo_lock); 2166 disk->major = LOOP_MAJOR; 2167 disk->first_minor = i << part_shift; 2168 disk->fops = &lo_fops; 2169 disk->private_data = lo; 2170 disk->queue = lo->lo_queue; 2171 sprintf(disk->disk_name, "loop%d", i); 2172 add_disk(disk); 2173 *l = lo; 2174 return lo->lo_number; 2175 2176out_free_queue: 2177 blk_cleanup_queue(lo->lo_queue); 2178out_cleanup_tags: 2179 blk_mq_free_tag_set(&lo->tag_set); 2180out_free_idr: 2181 idr_remove(&loop_index_idr, i); 2182out_free_dev: 2183 kfree(lo); 2184out: 2185 return err; 2186} 2187 2188static void loop_remove(struct loop_device *lo) 2189{ 2190 del_gendisk(lo->lo_disk); 2191 blk_cleanup_queue(lo->lo_queue); 2192 blk_mq_free_tag_set(&lo->tag_set); 2193 put_disk(lo->lo_disk); 2194 kfree(lo); 2195} 2196 2197static int find_free_cb(int id, void *ptr, void *data) 2198{ 2199 struct loop_device *lo = ptr; 2200 struct loop_device **l = data; 2201 2202 if (lo->lo_state == Lo_unbound) { 2203 *l = lo; 2204 return 1; 2205 } 2206 return 0; 2207} 2208 2209static int loop_lookup(struct loop_device **l, int i) 2210{ 2211 struct loop_device *lo; 2212 int ret = -ENODEV; 2213 2214 if (i < 0) { 2215 int err; 2216 2217 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo); 2218 if (err == 1) { 2219 *l = lo; 2220 ret = lo->lo_number; 2221 } 2222 goto out; 2223 } 2224 2225 /* lookup and return a specific i */ 2226 lo = idr_find(&loop_index_idr, i); 2227 if (lo) { 2228 *l = lo; 2229 ret = lo->lo_number; 2230 } 2231out: 2232 return ret; 2233} 2234 2235static struct kobject *loop_probe(dev_t dev, int *part, void *data) 2236{ 2237 struct loop_device *lo; 2238 struct kobject *kobj; 2239 int err; 2240 2241 mutex_lock(&loop_ctl_mutex); 2242 err = loop_lookup(&lo, MINOR(dev) >> part_shift); 2243 if (err < 0) 2244 err = loop_add(&lo, MINOR(dev) >> part_shift); 2245 if (err < 0) 2246 kobj = NULL; 2247 else 2248 kobj = get_disk_and_module(lo->lo_disk); 2249 mutex_unlock(&loop_ctl_mutex); 2250 2251 *part = 0; 2252 return kobj; 2253} 2254 2255static long loop_control_ioctl(struct file *file, unsigned int cmd, 2256 unsigned long parm) 2257{ 2258 struct loop_device *lo; 2259 int ret; 2260 2261 ret = mutex_lock_killable(&loop_ctl_mutex); 2262 if (ret) 2263 return ret; 2264 2265 ret = -ENOSYS; 2266 switch (cmd) { 2267 case LOOP_CTL_ADD: 2268 ret = loop_lookup(&lo, parm); 2269 if (ret >= 0) { 2270 ret = -EEXIST; 2271 break; 2272 } 2273 ret = loop_add(&lo, parm); 2274 break; 2275 case LOOP_CTL_REMOVE: 2276 ret = loop_lookup(&lo, parm); 2277 if (ret < 0) 2278 break; 2279 if (lo->lo_state != Lo_unbound) { 2280 ret = -EBUSY; 2281 break; 2282 } 2283 if (atomic_read(&lo->lo_refcnt) > 0) { 2284 ret = -EBUSY; 2285 break; 2286 } 2287 lo->lo_disk->private_data = NULL; 2288 idr_remove(&loop_index_idr, lo->lo_number); 2289 loop_remove(lo); 2290 break; 2291 case LOOP_CTL_GET_FREE: 2292 ret = loop_lookup(&lo, -1); 2293 if (ret >= 0) 2294 break; 2295 ret = loop_add(&lo, -1); 2296 } 2297 mutex_unlock(&loop_ctl_mutex); 2298 2299 return ret; 2300} 2301 2302static const struct file_operations loop_ctl_fops = { 2303 .open = nonseekable_open, 2304 .unlocked_ioctl = loop_control_ioctl, 2305 .compat_ioctl = loop_control_ioctl, 2306 .owner = THIS_MODULE, 2307 .llseek = noop_llseek, 2308}; 2309 2310static struct miscdevice loop_misc = { 2311 .minor = LOOP_CTRL_MINOR, 2312 .name = "loop-control", 2313 .fops = &loop_ctl_fops, 2314}; 2315 2316MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); 2317MODULE_ALIAS("devname:loop-control"); 2318 2319static int __init loop_init(void) 2320{ 2321 int i, nr; 2322 unsigned long range; 2323 struct loop_device *lo; 2324 int err; 2325 2326 part_shift = 0; 2327 if (max_part > 0) { 2328 part_shift = fls(max_part); 2329 2330 /* 2331 * Adjust max_part according to part_shift as it is exported 2332 * to user space so that user can decide correct minor number 2333 * if [s]he want to create more devices. 2334 * 2335 * Note that -1 is required because partition 0 is reserved 2336 * for the whole disk. 2337 */ 2338 max_part = (1UL << part_shift) - 1; 2339 } 2340 2341 if ((1UL << part_shift) > DISK_MAX_PARTS) { 2342 err = -EINVAL; 2343 goto err_out; 2344 } 2345 2346 if (max_loop > 1UL << (MINORBITS - part_shift)) { 2347 err = -EINVAL; 2348 goto err_out; 2349 } 2350 2351 /* 2352 * If max_loop is specified, create that many devices upfront. 2353 * This also becomes a hard limit. If max_loop is not specified, 2354 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module 2355 * init time. Loop devices can be requested on-demand with the 2356 * /dev/loop-control interface, or be instantiated by accessing 2357 * a 'dead' device node. 2358 */ 2359 if (max_loop) { 2360 nr = max_loop; 2361 range = max_loop << part_shift; 2362 } else { 2363 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT; 2364 range = 1UL << MINORBITS; 2365 } 2366 2367 err = misc_register(&loop_misc); 2368 if (err < 0) 2369 goto err_out; 2370 2371 2372 if (register_blkdev(LOOP_MAJOR, "loop")) { 2373 err = -EIO; 2374 goto misc_out; 2375 } 2376 2377 blk_register_region(MKDEV(LOOP_MAJOR, 0), range, 2378 THIS_MODULE, loop_probe, NULL, NULL); 2379 2380 /* pre-create number of devices given by config or max_loop */ 2381 mutex_lock(&loop_ctl_mutex); 2382 for (i = 0; i < nr; i++) 2383 loop_add(&lo, i); 2384 mutex_unlock(&loop_ctl_mutex); 2385 2386 printk(KERN_INFO "loop: module loaded\n"); 2387 return 0; 2388 2389misc_out: 2390 misc_deregister(&loop_misc); 2391err_out: 2392 return err; 2393} 2394 2395static int loop_exit_cb(int id, void *ptr, void *data) 2396{ 2397 struct loop_device *lo = ptr; 2398 2399 loop_remove(lo); 2400 return 0; 2401} 2402 2403static void __exit loop_exit(void) 2404{ 2405 unsigned long range; 2406 2407 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS; 2408 2409 mutex_lock(&loop_ctl_mutex); 2410 2411 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL); 2412 idr_destroy(&loop_index_idr); 2413 2414 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range); 2415 unregister_blkdev(LOOP_MAJOR, "loop"); 2416 2417 misc_deregister(&loop_misc); 2418 2419 mutex_unlock(&loop_ctl_mutex); 2420} 2421 2422module_init(loop_init); 2423module_exit(loop_exit); 2424 2425#ifndef MODULE 2426static int __init max_loop_setup(char *str) 2427{ 2428 max_loop = simple_strtol(str, NULL, 0); 2429 return 1; 2430} 2431 2432__setup("max_loop=", max_loop_setup); 2433#endif 2434