1// SPDX-License-Identifier: GPL-2.0-only 2/* 3 * Copyright 1993 by Theodore Ts'o. 4 */ 5#include <linux/module.h> 6#include <linux/moduleparam.h> 7#include <linux/sched.h> 8#include <linux/fs.h> 9#include <linux/pagemap.h> 10#include <linux/file.h> 11#include <linux/stat.h> 12#include <linux/errno.h> 13#include <linux/major.h> 14#include <linux/wait.h> 15#include <linux/blkpg.h> 16#include <linux/init.h> 17#include <linux/swap.h> 18#include <linux/slab.h> 19#include <linux/compat.h> 20#include <linux/suspend.h> 21#include <linux/freezer.h> 22#include <linux/mutex.h> 23#include <linux/writeback.h> 24#include <linux/completion.h> 25#include <linux/highmem.h> 26#include <linux/splice.h> 27#include <linux/sysfs.h> 28#include <linux/miscdevice.h> 29#include <linux/falloc.h> 30#include <linux/uio.h> 31#include <linux/ioprio.h> 32#include <linux/blk-cgroup.h> 33#include <linux/sched/mm.h> 34#include <linux/statfs.h> 35#include <linux/uaccess.h> 36#include <linux/blk-mq.h> 37#include <linux/spinlock.h> 38#include <uapi/linux/loop.h> 39 40/* Possible states of device */ 41enum { 42 Lo_unbound, 43 Lo_bound, 44 Lo_rundown, 45 Lo_deleting, 46}; 47 48struct loop_func_table; 49 50struct loop_device { 51 int lo_number; 52 loff_t lo_offset; 53 loff_t lo_sizelimit; 54 int lo_flags; 55 char lo_file_name[LO_NAME_SIZE]; 56 57 struct file * lo_backing_file; 58 struct block_device *lo_device; 59 60 gfp_t old_gfp_mask; 61 62 spinlock_t lo_lock; 63 int lo_state; 64 spinlock_t lo_work_lock; 65 struct workqueue_struct *workqueue; 66 struct work_struct rootcg_work; 67 struct list_head rootcg_cmd_list; 68 struct list_head idle_worker_list; 69 struct rb_root worker_tree; 70 struct timer_list timer; 71 bool use_dio; 72 bool sysfs_inited; 73 74 struct request_queue *lo_queue; 75 struct blk_mq_tag_set tag_set; 76 struct gendisk *lo_disk; 77 struct mutex lo_mutex; 78 bool idr_visible; 79}; 80 81struct loop_cmd { 82 struct list_head list_entry; 83 bool use_aio; /* use AIO interface to handle I/O */ 84 atomic_t ref; /* only for aio */ 85 long ret; 86 struct kiocb iocb; 87 struct bio_vec *bvec; 88 struct cgroup_subsys_state *blkcg_css; 89 struct cgroup_subsys_state *memcg_css; 90}; 91 92#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ) 93#define LOOP_DEFAULT_HW_Q_DEPTH 128 94 95static DEFINE_IDR(loop_index_idr); 96static DEFINE_MUTEX(loop_ctl_mutex); 97static DEFINE_MUTEX(loop_validate_mutex); 98 99/** 100 * loop_global_lock_killable() - take locks for safe loop_validate_file() test 101 * 102 * @lo: struct loop_device 103 * @global: true if @lo is about to bind another "struct loop_device", false otherwise 104 * 105 * Returns 0 on success, -EINTR otherwise. 106 * 107 * Since loop_validate_file() traverses on other "struct loop_device" if 108 * is_loop_device() is true, we need a global lock for serializing concurrent 109 * loop_configure()/loop_change_fd()/__loop_clr_fd() calls. 110 */ 111static int loop_global_lock_killable(struct loop_device *lo, bool global) 112{ 113 int err; 114 115 if (global) { 116 err = mutex_lock_killable(&loop_validate_mutex); 117 if (err) 118 return err; 119 } 120 err = mutex_lock_killable(&lo->lo_mutex); 121 if (err && global) 122 mutex_unlock(&loop_validate_mutex); 123 return err; 124} 125 126/** 127 * loop_global_unlock() - release locks taken by loop_global_lock_killable() 128 * 129 * @lo: struct loop_device 130 * @global: true if @lo was about to bind another "struct loop_device", false otherwise 131 */ 132static void loop_global_unlock(struct loop_device *lo, bool global) 133{ 134 mutex_unlock(&lo->lo_mutex); 135 if (global) 136 mutex_unlock(&loop_validate_mutex); 137} 138 139static int max_part; 140static int part_shift; 141 142static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file) 143{ 144 loff_t loopsize; 145 146 /* Compute loopsize in bytes */ 147 loopsize = i_size_read(file->f_mapping->host); 148 if (offset > 0) 149 loopsize -= offset; 150 /* offset is beyond i_size, weird but possible */ 151 if (loopsize < 0) 152 return 0; 153 154 if (sizelimit > 0 && sizelimit < loopsize) 155 loopsize = sizelimit; 156 /* 157 * Unfortunately, if we want to do I/O on the device, 158 * the number of 512-byte sectors has to fit into a sector_t. 159 */ 160 return loopsize >> 9; 161} 162 163static loff_t get_loop_size(struct loop_device *lo, struct file *file) 164{ 165 return get_size(lo->lo_offset, lo->lo_sizelimit, file); 166} 167 168/* 169 * We support direct I/O only if lo_offset is aligned with the logical I/O size 170 * of backing device, and the logical block size of loop is bigger than that of 171 * the backing device. 172 */ 173static bool lo_bdev_can_use_dio(struct loop_device *lo, 174 struct block_device *backing_bdev) 175{ 176 unsigned short sb_bsize = bdev_logical_block_size(backing_bdev); 177 178 if (queue_logical_block_size(lo->lo_queue) < sb_bsize) 179 return false; 180 if (lo->lo_offset & (sb_bsize - 1)) 181 return false; 182 return true; 183} 184 185static void __loop_update_dio(struct loop_device *lo, bool dio) 186{ 187 struct file *file = lo->lo_backing_file; 188 struct inode *inode = file->f_mapping->host; 189 struct block_device *backing_bdev = NULL; 190 bool use_dio; 191 192 if (S_ISBLK(inode->i_mode)) 193 backing_bdev = I_BDEV(inode); 194 else if (inode->i_sb->s_bdev) 195 backing_bdev = inode->i_sb->s_bdev; 196 197 use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) && 198 (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev)); 199 200 if (lo->use_dio == use_dio) 201 return; 202 203 /* flush dirty pages before changing direct IO */ 204 vfs_fsync(file, 0); 205 206 /* 207 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with 208 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup 209 * will get updated by ioctl(LOOP_GET_STATUS) 210 */ 211 if (lo->lo_state == Lo_bound) 212 blk_mq_freeze_queue(lo->lo_queue); 213 lo->use_dio = use_dio; 214 if (use_dio) { 215 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue); 216 lo->lo_flags |= LO_FLAGS_DIRECT_IO; 217 } else { 218 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); 219 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO; 220 } 221 if (lo->lo_state == Lo_bound) 222 blk_mq_unfreeze_queue(lo->lo_queue); 223} 224 225/** 226 * loop_set_size() - sets device size and notifies userspace 227 * @lo: struct loop_device to set the size for 228 * @size: new size of the loop device 229 * 230 * Callers must validate that the size passed into this function fits into 231 * a sector_t, eg using loop_validate_size() 232 */ 233static void loop_set_size(struct loop_device *lo, loff_t size) 234{ 235 if (!set_capacity_and_notify(lo->lo_disk, size)) 236 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); 237} 238 239static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos) 240{ 241 struct iov_iter i; 242 ssize_t bw; 243 244 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len); 245 246 bw = vfs_iter_write(file, &i, ppos, 0); 247 248 if (likely(bw == bvec->bv_len)) 249 return 0; 250 251 printk_ratelimited(KERN_ERR 252 "loop: Write error at byte offset %llu, length %i.\n", 253 (unsigned long long)*ppos, bvec->bv_len); 254 if (bw >= 0) 255 bw = -EIO; 256 return bw; 257} 258 259static int lo_write_simple(struct loop_device *lo, struct request *rq, 260 loff_t pos) 261{ 262 struct bio_vec bvec; 263 struct req_iterator iter; 264 int ret = 0; 265 266 rq_for_each_segment(bvec, rq, iter) { 267 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos); 268 if (ret < 0) 269 break; 270 cond_resched(); 271 } 272 273 return ret; 274} 275 276static int lo_read_simple(struct loop_device *lo, struct request *rq, 277 loff_t pos) 278{ 279 struct bio_vec bvec; 280 struct req_iterator iter; 281 struct iov_iter i; 282 ssize_t len; 283 284 rq_for_each_segment(bvec, rq, iter) { 285 iov_iter_bvec(&i, ITER_DEST, &bvec, 1, bvec.bv_len); 286 len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0); 287 if (len < 0) 288 return len; 289 290 flush_dcache_page(bvec.bv_page); 291 292 if (len != bvec.bv_len) { 293 struct bio *bio; 294 295 __rq_for_each_bio(bio, rq) 296 zero_fill_bio(bio); 297 break; 298 } 299 cond_resched(); 300 } 301 302 return 0; 303} 304 305static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos, 306 int mode) 307{ 308 /* 309 * We use fallocate to manipulate the space mappings used by the image 310 * a.k.a. discard/zerorange. 311 */ 312 struct file *file = lo->lo_backing_file; 313 int ret; 314 315 mode |= FALLOC_FL_KEEP_SIZE; 316 317 if (!bdev_max_discard_sectors(lo->lo_device)) 318 return -EOPNOTSUPP; 319 320 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq)); 321 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP)) 322 return -EIO; 323 return ret; 324} 325 326static int lo_req_flush(struct loop_device *lo, struct request *rq) 327{ 328 int ret = vfs_fsync(lo->lo_backing_file, 0); 329 if (unlikely(ret && ret != -EINVAL)) 330 ret = -EIO; 331 332 return ret; 333} 334 335static void lo_complete_rq(struct request *rq) 336{ 337 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 338 blk_status_t ret = BLK_STS_OK; 339 340 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) || 341 req_op(rq) != REQ_OP_READ) { 342 if (cmd->ret < 0) 343 ret = errno_to_blk_status(cmd->ret); 344 goto end_io; 345 } 346 347 /* 348 * Short READ - if we got some data, advance our request and 349 * retry it. If we got no data, end the rest with EIO. 350 */ 351 if (cmd->ret) { 352 blk_update_request(rq, BLK_STS_OK, cmd->ret); 353 cmd->ret = 0; 354 blk_mq_requeue_request(rq, true); 355 } else { 356 if (cmd->use_aio) { 357 struct bio *bio = rq->bio; 358 359 while (bio) { 360 zero_fill_bio(bio); 361 bio = bio->bi_next; 362 } 363 } 364 ret = BLK_STS_IOERR; 365end_io: 366 blk_mq_end_request(rq, ret); 367 } 368} 369 370static void lo_rw_aio_do_completion(struct loop_cmd *cmd) 371{ 372 struct request *rq = blk_mq_rq_from_pdu(cmd); 373 374 if (!atomic_dec_and_test(&cmd->ref)) 375 return; 376 kfree(cmd->bvec); 377 cmd->bvec = NULL; 378 if (likely(!blk_should_fake_timeout(rq->q))) 379 blk_mq_complete_request(rq); 380} 381 382static void lo_rw_aio_complete(struct kiocb *iocb, long ret) 383{ 384 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb); 385 386 cmd->ret = ret; 387 lo_rw_aio_do_completion(cmd); 388} 389 390static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd, 391 loff_t pos, int rw) 392{ 393 struct iov_iter iter; 394 struct req_iterator rq_iter; 395 struct bio_vec *bvec; 396 struct request *rq = blk_mq_rq_from_pdu(cmd); 397 struct bio *bio = rq->bio; 398 struct file *file = lo->lo_backing_file; 399 struct bio_vec tmp; 400 unsigned int offset; 401 int nr_bvec = 0; 402 int ret; 403 404 rq_for_each_bvec(tmp, rq, rq_iter) 405 nr_bvec++; 406 407 if (rq->bio != rq->biotail) { 408 409 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec), 410 GFP_NOIO); 411 if (!bvec) 412 return -EIO; 413 cmd->bvec = bvec; 414 415 /* 416 * The bios of the request may be started from the middle of 417 * the 'bvec' because of bio splitting, so we can't directly 418 * copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec 419 * API will take care of all details for us. 420 */ 421 rq_for_each_bvec(tmp, rq, rq_iter) { 422 *bvec = tmp; 423 bvec++; 424 } 425 bvec = cmd->bvec; 426 offset = 0; 427 } else { 428 /* 429 * Same here, this bio may be started from the middle of the 430 * 'bvec' because of bio splitting, so offset from the bvec 431 * must be passed to iov iterator 432 */ 433 offset = bio->bi_iter.bi_bvec_done; 434 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter); 435 } 436 atomic_set(&cmd->ref, 2); 437 438 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq)); 439 iter.iov_offset = offset; 440 441 cmd->iocb.ki_pos = pos; 442 cmd->iocb.ki_filp = file; 443 cmd->iocb.ki_complete = lo_rw_aio_complete; 444 cmd->iocb.ki_flags = IOCB_DIRECT; 445 cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); 446 447 if (rw == ITER_SOURCE) 448 ret = call_write_iter(file, &cmd->iocb, &iter); 449 else 450 ret = call_read_iter(file, &cmd->iocb, &iter); 451 452 lo_rw_aio_do_completion(cmd); 453 454 if (ret != -EIOCBQUEUED) 455 lo_rw_aio_complete(&cmd->iocb, ret); 456 return 0; 457} 458 459static int do_req_filebacked(struct loop_device *lo, struct request *rq) 460{ 461 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 462 loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset; 463 464 /* 465 * lo_write_simple and lo_read_simple should have been covered 466 * by io submit style function like lo_rw_aio(), one blocker 467 * is that lo_read_simple() need to call flush_dcache_page after 468 * the page is written from kernel, and it isn't easy to handle 469 * this in io submit style function which submits all segments 470 * of the req at one time. And direct read IO doesn't need to 471 * run flush_dcache_page(). 472 */ 473 switch (req_op(rq)) { 474 case REQ_OP_FLUSH: 475 return lo_req_flush(lo, rq); 476 case REQ_OP_WRITE_ZEROES: 477 /* 478 * If the caller doesn't want deallocation, call zeroout to 479 * write zeroes the range. Otherwise, punch them out. 480 */ 481 return lo_fallocate(lo, rq, pos, 482 (rq->cmd_flags & REQ_NOUNMAP) ? 483 FALLOC_FL_ZERO_RANGE : 484 FALLOC_FL_PUNCH_HOLE); 485 case REQ_OP_DISCARD: 486 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE); 487 case REQ_OP_WRITE: 488 if (cmd->use_aio) 489 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE); 490 else 491 return lo_write_simple(lo, rq, pos); 492 case REQ_OP_READ: 493 if (cmd->use_aio) 494 return lo_rw_aio(lo, cmd, pos, ITER_DEST); 495 else 496 return lo_read_simple(lo, rq, pos); 497 default: 498 WARN_ON_ONCE(1); 499 return -EIO; 500 } 501} 502 503static inline void loop_update_dio(struct loop_device *lo) 504{ 505 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) | 506 lo->use_dio); 507} 508 509static void loop_reread_partitions(struct loop_device *lo) 510{ 511 int rc; 512 513 mutex_lock(&lo->lo_disk->open_mutex); 514 rc = bdev_disk_changed(lo->lo_disk, false); 515 mutex_unlock(&lo->lo_disk->open_mutex); 516 if (rc) 517 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n", 518 __func__, lo->lo_number, lo->lo_file_name, rc); 519} 520 521static inline int is_loop_device(struct file *file) 522{ 523 struct inode *i = file->f_mapping->host; 524 525 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR; 526} 527 528static int loop_validate_file(struct file *file, struct block_device *bdev) 529{ 530 struct inode *inode = file->f_mapping->host; 531 struct file *f = file; 532 533 /* Avoid recursion */ 534 while (is_loop_device(f)) { 535 struct loop_device *l; 536 537 lockdep_assert_held(&loop_validate_mutex); 538 if (f->f_mapping->host->i_rdev == bdev->bd_dev) 539 return -EBADF; 540 541 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data; 542 if (l->lo_state != Lo_bound) 543 return -EINVAL; 544 /* Order wrt setting lo->lo_backing_file in loop_configure(). */ 545 rmb(); 546 f = l->lo_backing_file; 547 } 548 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode)) 549 return -EINVAL; 550 return 0; 551} 552 553/* 554 * loop_change_fd switched the backing store of a loopback device to 555 * a new file. This is useful for operating system installers to free up 556 * the original file and in High Availability environments to switch to 557 * an alternative location for the content in case of server meltdown. 558 * This can only work if the loop device is used read-only, and if the 559 * new backing store is the same size and type as the old backing store. 560 */ 561static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, 562 unsigned int arg) 563{ 564 struct file *file = fget(arg); 565 struct file *old_file; 566 int error; 567 bool partscan; 568 bool is_loop; 569 570 if (!file) 571 return -EBADF; 572 573 /* suppress uevents while reconfiguring the device */ 574 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); 575 576 is_loop = is_loop_device(file); 577 error = loop_global_lock_killable(lo, is_loop); 578 if (error) 579 goto out_putf; 580 error = -ENXIO; 581 if (lo->lo_state != Lo_bound) 582 goto out_err; 583 584 /* the loop device has to be read-only */ 585 error = -EINVAL; 586 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY)) 587 goto out_err; 588 589 error = loop_validate_file(file, bdev); 590 if (error) 591 goto out_err; 592 593 old_file = lo->lo_backing_file; 594 595 error = -EINVAL; 596 597 /* size of the new backing store needs to be the same */ 598 if (get_loop_size(lo, file) != get_loop_size(lo, old_file)) 599 goto out_err; 600 601 /* and ... switch */ 602 disk_force_media_change(lo->lo_disk); 603 blk_mq_freeze_queue(lo->lo_queue); 604 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask); 605 lo->lo_backing_file = file; 606 lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping); 607 mapping_set_gfp_mask(file->f_mapping, 608 lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 609 loop_update_dio(lo); 610 blk_mq_unfreeze_queue(lo->lo_queue); 611 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; 612 loop_global_unlock(lo, is_loop); 613 614 /* 615 * Flush loop_validate_file() before fput(), for l->lo_backing_file 616 * might be pointing at old_file which might be the last reference. 617 */ 618 if (!is_loop) { 619 mutex_lock(&loop_validate_mutex); 620 mutex_unlock(&loop_validate_mutex); 621 } 622 /* 623 * We must drop file reference outside of lo_mutex as dropping 624 * the file ref can take open_mutex which creates circular locking 625 * dependency. 626 */ 627 fput(old_file); 628 if (partscan) 629 loop_reread_partitions(lo); 630 631 error = 0; 632done: 633 /* enable and uncork uevent now that we are done */ 634 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); 635 return error; 636 637out_err: 638 loop_global_unlock(lo, is_loop); 639out_putf: 640 fput(file); 641 goto done; 642} 643 644/* loop sysfs attributes */ 645 646static ssize_t loop_attr_show(struct device *dev, char *page, 647 ssize_t (*callback)(struct loop_device *, char *)) 648{ 649 struct gendisk *disk = dev_to_disk(dev); 650 struct loop_device *lo = disk->private_data; 651 652 return callback(lo, page); 653} 654 655#define LOOP_ATTR_RO(_name) \ 656static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \ 657static ssize_t loop_attr_do_show_##_name(struct device *d, \ 658 struct device_attribute *attr, char *b) \ 659{ \ 660 return loop_attr_show(d, b, loop_attr_##_name##_show); \ 661} \ 662static struct device_attribute loop_attr_##_name = \ 663 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL); 664 665static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf) 666{ 667 ssize_t ret; 668 char *p = NULL; 669 670 spin_lock_irq(&lo->lo_lock); 671 if (lo->lo_backing_file) 672 p = file_path(lo->lo_backing_file, buf, PAGE_SIZE - 1); 673 spin_unlock_irq(&lo->lo_lock); 674 675 if (IS_ERR_OR_NULL(p)) 676 ret = PTR_ERR(p); 677 else { 678 ret = strlen(p); 679 memmove(buf, p, ret); 680 buf[ret++] = '\n'; 681 buf[ret] = 0; 682 } 683 684 return ret; 685} 686 687static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf) 688{ 689 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset); 690} 691 692static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf) 693{ 694 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit); 695} 696 697static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf) 698{ 699 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR); 700 701 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0"); 702} 703 704static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) 705{ 706 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN); 707 708 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0"); 709} 710 711static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf) 712{ 713 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO); 714 715 return sysfs_emit(buf, "%s\n", dio ? "1" : "0"); 716} 717 718LOOP_ATTR_RO(backing_file); 719LOOP_ATTR_RO(offset); 720LOOP_ATTR_RO(sizelimit); 721LOOP_ATTR_RO(autoclear); 722LOOP_ATTR_RO(partscan); 723LOOP_ATTR_RO(dio); 724 725static struct attribute *loop_attrs[] = { 726 &loop_attr_backing_file.attr, 727 &loop_attr_offset.attr, 728 &loop_attr_sizelimit.attr, 729 &loop_attr_autoclear.attr, 730 &loop_attr_partscan.attr, 731 &loop_attr_dio.attr, 732 NULL, 733}; 734 735static struct attribute_group loop_attribute_group = { 736 .name = "loop", 737 .attrs= loop_attrs, 738}; 739 740static void loop_sysfs_init(struct loop_device *lo) 741{ 742 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj, 743 &loop_attribute_group); 744} 745 746static void loop_sysfs_exit(struct loop_device *lo) 747{ 748 if (lo->sysfs_inited) 749 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj, 750 &loop_attribute_group); 751} 752 753static void loop_config_discard(struct loop_device *lo, 754 struct queue_limits *lim) 755{ 756 struct file *file = lo->lo_backing_file; 757 struct inode *inode = file->f_mapping->host; 758 u32 granularity = 0, max_discard_sectors = 0; 759 struct kstatfs sbuf; 760 761 /* 762 * If the backing device is a block device, mirror its zeroing 763 * capability. Set the discard sectors to the block device's zeroing 764 * capabilities because loop discards result in blkdev_issue_zeroout(), 765 * not blkdev_issue_discard(). This maintains consistent behavior with 766 * file-backed loop devices: discarded regions read back as zero. 767 */ 768 if (S_ISBLK(inode->i_mode)) { 769 struct request_queue *backingq = bdev_get_queue(I_BDEV(inode)); 770 771 max_discard_sectors = backingq->limits.max_write_zeroes_sectors; 772 granularity = bdev_discard_granularity(I_BDEV(inode)) ?: 773 queue_physical_block_size(backingq); 774 775 /* 776 * We use punch hole to reclaim the free space used by the 777 * image a.k.a. discard. 778 */ 779 } else if (file->f_op->fallocate && !vfs_statfs(&file->f_path, &sbuf)) { 780 max_discard_sectors = UINT_MAX >> 9; 781 granularity = sbuf.f_bsize; 782 } 783 784 lim->max_hw_discard_sectors = max_discard_sectors; 785 lim->max_write_zeroes_sectors = max_discard_sectors; 786 if (max_discard_sectors) 787 lim->discard_granularity = granularity; 788 else 789 lim->discard_granularity = 0; 790} 791 792struct loop_worker { 793 struct rb_node rb_node; 794 struct work_struct work; 795 struct list_head cmd_list; 796 struct list_head idle_list; 797 struct loop_device *lo; 798 struct cgroup_subsys_state *blkcg_css; 799 unsigned long last_ran_at; 800}; 801 802static void loop_workfn(struct work_struct *work); 803 804#ifdef CONFIG_BLK_CGROUP 805static inline int queue_on_root_worker(struct cgroup_subsys_state *css) 806{ 807 return !css || css == blkcg_root_css; 808} 809#else 810static inline int queue_on_root_worker(struct cgroup_subsys_state *css) 811{ 812 return !css; 813} 814#endif 815 816static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd) 817{ 818 struct rb_node **node, *parent = NULL; 819 struct loop_worker *cur_worker, *worker = NULL; 820 struct work_struct *work; 821 struct list_head *cmd_list; 822 823 spin_lock_irq(&lo->lo_work_lock); 824 825 if (queue_on_root_worker(cmd->blkcg_css)) 826 goto queue_work; 827 828 node = &lo->worker_tree.rb_node; 829 830 while (*node) { 831 parent = *node; 832 cur_worker = container_of(*node, struct loop_worker, rb_node); 833 if (cur_worker->blkcg_css == cmd->blkcg_css) { 834 worker = cur_worker; 835 break; 836 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) { 837 node = &(*node)->rb_left; 838 } else { 839 node = &(*node)->rb_right; 840 } 841 } 842 if (worker) 843 goto queue_work; 844 845 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); 846 /* 847 * In the event we cannot allocate a worker, just queue on the 848 * rootcg worker and issue the I/O as the rootcg 849 */ 850 if (!worker) { 851 cmd->blkcg_css = NULL; 852 if (cmd->memcg_css) 853 css_put(cmd->memcg_css); 854 cmd->memcg_css = NULL; 855 goto queue_work; 856 } 857 858 worker->blkcg_css = cmd->blkcg_css; 859 css_get(worker->blkcg_css); 860 INIT_WORK(&worker->work, loop_workfn); 861 INIT_LIST_HEAD(&worker->cmd_list); 862 INIT_LIST_HEAD(&worker->idle_list); 863 worker->lo = lo; 864 rb_link_node(&worker->rb_node, parent, node); 865 rb_insert_color(&worker->rb_node, &lo->worker_tree); 866queue_work: 867 if (worker) { 868 /* 869 * We need to remove from the idle list here while 870 * holding the lock so that the idle timer doesn't 871 * free the worker 872 */ 873 if (!list_empty(&worker->idle_list)) 874 list_del_init(&worker->idle_list); 875 work = &worker->work; 876 cmd_list = &worker->cmd_list; 877 } else { 878 work = &lo->rootcg_work; 879 cmd_list = &lo->rootcg_cmd_list; 880 } 881 list_add_tail(&cmd->list_entry, cmd_list); 882 queue_work(lo->workqueue, work); 883 spin_unlock_irq(&lo->lo_work_lock); 884} 885 886static void loop_set_timer(struct loop_device *lo) 887{ 888 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT); 889} 890 891static void loop_free_idle_workers(struct loop_device *lo, bool delete_all) 892{ 893 struct loop_worker *pos, *worker; 894 895 spin_lock_irq(&lo->lo_work_lock); 896 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, 897 idle_list) { 898 if (!delete_all && 899 time_is_after_jiffies(worker->last_ran_at + 900 LOOP_IDLE_WORKER_TIMEOUT)) 901 break; 902 list_del(&worker->idle_list); 903 rb_erase(&worker->rb_node, &lo->worker_tree); 904 css_put(worker->blkcg_css); 905 kfree(worker); 906 } 907 if (!list_empty(&lo->idle_worker_list)) 908 loop_set_timer(lo); 909 spin_unlock_irq(&lo->lo_work_lock); 910} 911 912static void loop_free_idle_workers_timer(struct timer_list *timer) 913{ 914 struct loop_device *lo = container_of(timer, struct loop_device, timer); 915 916 return loop_free_idle_workers(lo, false); 917} 918 919static void loop_update_rotational(struct loop_device *lo) 920{ 921 struct file *file = lo->lo_backing_file; 922 struct inode *file_inode = file->f_mapping->host; 923 struct block_device *file_bdev = file_inode->i_sb->s_bdev; 924 struct request_queue *q = lo->lo_queue; 925 bool nonrot = true; 926 927 /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */ 928 if (file_bdev) 929 nonrot = bdev_nonrot(file_bdev); 930 931 if (nonrot) 932 blk_queue_flag_set(QUEUE_FLAG_NONROT, q); 933 else 934 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q); 935} 936 937/** 938 * loop_set_status_from_info - configure device from loop_info 939 * @lo: struct loop_device to configure 940 * @info: struct loop_info64 to configure the device with 941 * 942 * Configures the loop device parameters according to the passed 943 * in loop_info64 configuration. 944 */ 945static int 946loop_set_status_from_info(struct loop_device *lo, 947 const struct loop_info64 *info) 948{ 949 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE) 950 return -EINVAL; 951 952 switch (info->lo_encrypt_type) { 953 case LO_CRYPT_NONE: 954 break; 955 case LO_CRYPT_XOR: 956 pr_warn("support for the xor transformation has been removed.\n"); 957 return -EINVAL; 958 case LO_CRYPT_CRYPTOAPI: 959 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n"); 960 return -EINVAL; 961 default: 962 return -EINVAL; 963 } 964 965 /* Avoid assigning overflow values */ 966 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX) 967 return -EOVERFLOW; 968 969 lo->lo_offset = info->lo_offset; 970 lo->lo_sizelimit = info->lo_sizelimit; 971 972 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); 973 lo->lo_file_name[LO_NAME_SIZE-1] = 0; 974 lo->lo_flags = info->lo_flags; 975 return 0; 976} 977 978static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize, 979 bool update_discard_settings) 980{ 981 struct queue_limits lim; 982 983 lim = queue_limits_start_update(lo->lo_queue); 984 lim.logical_block_size = bsize; 985 lim.physical_block_size = bsize; 986 lim.io_min = bsize; 987 if (update_discard_settings) 988 loop_config_discard(lo, &lim); 989 return queue_limits_commit_update(lo->lo_queue, &lim); 990} 991 992static int loop_configure(struct loop_device *lo, blk_mode_t mode, 993 struct block_device *bdev, 994 const struct loop_config *config) 995{ 996 struct file *file = fget(config->fd); 997 struct inode *inode; 998 struct address_space *mapping; 999 int error; 1000 loff_t size; 1001 bool partscan; 1002 unsigned short bsize; 1003 bool is_loop; 1004 1005 if (!file) 1006 return -EBADF; 1007 is_loop = is_loop_device(file); 1008 1009 /* This is safe, since we have a reference from open(). */ 1010 __module_get(THIS_MODULE); 1011 1012 /* 1013 * If we don't hold exclusive handle for the device, upgrade to it 1014 * here to avoid changing device under exclusive owner. 1015 */ 1016 if (!(mode & BLK_OPEN_EXCL)) { 1017 error = bd_prepare_to_claim(bdev, loop_configure, NULL); 1018 if (error) 1019 goto out_putf; 1020 } 1021 1022 error = loop_global_lock_killable(lo, is_loop); 1023 if (error) 1024 goto out_bdev; 1025 1026 error = -EBUSY; 1027 if (lo->lo_state != Lo_unbound) 1028 goto out_unlock; 1029 1030 error = loop_validate_file(file, bdev); 1031 if (error) 1032 goto out_unlock; 1033 1034 mapping = file->f_mapping; 1035 inode = mapping->host; 1036 1037 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) { 1038 error = -EINVAL; 1039 goto out_unlock; 1040 } 1041 1042 if (config->block_size) { 1043 error = blk_validate_block_size(config->block_size); 1044 if (error) 1045 goto out_unlock; 1046 } 1047 1048 error = loop_set_status_from_info(lo, &config->info); 1049 if (error) 1050 goto out_unlock; 1051 1052 if (!(file->f_mode & FMODE_WRITE) || !(mode & BLK_OPEN_WRITE) || 1053 !file->f_op->write_iter) 1054 lo->lo_flags |= LO_FLAGS_READ_ONLY; 1055 1056 if (!lo->workqueue) { 1057 lo->workqueue = alloc_workqueue("loop%d", 1058 WQ_UNBOUND | WQ_FREEZABLE, 1059 0, lo->lo_number); 1060 if (!lo->workqueue) { 1061 error = -ENOMEM; 1062 goto out_unlock; 1063 } 1064 } 1065 1066 /* suppress uevents while reconfiguring the device */ 1067 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); 1068 1069 disk_force_media_change(lo->lo_disk); 1070 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0); 1071 1072 lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO; 1073 lo->lo_device = bdev; 1074 lo->lo_backing_file = file; 1075 lo->old_gfp_mask = mapping_gfp_mask(mapping); 1076 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); 1077 1078 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) 1079 blk_queue_write_cache(lo->lo_queue, true, false); 1080 1081 if (config->block_size) 1082 bsize = config->block_size; 1083 else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev) 1084 /* In case of direct I/O, match underlying block size */ 1085 bsize = bdev_logical_block_size(inode->i_sb->s_bdev); 1086 else 1087 bsize = 512; 1088 1089 error = loop_reconfigure_limits(lo, bsize, true); 1090 if (WARN_ON_ONCE(error)) 1091 goto out_unlock; 1092 1093 loop_update_rotational(lo); 1094 loop_update_dio(lo); 1095 loop_sysfs_init(lo); 1096 1097 size = get_loop_size(lo, file); 1098 loop_set_size(lo, size); 1099 1100 /* Order wrt reading lo_state in loop_validate_file(). */ 1101 wmb(); 1102 1103 lo->lo_state = Lo_bound; 1104 if (part_shift) 1105 lo->lo_flags |= LO_FLAGS_PARTSCAN; 1106 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN; 1107 if (partscan) 1108 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); 1109 1110 /* enable and uncork uevent now that we are done */ 1111 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0); 1112 1113 loop_global_unlock(lo, is_loop); 1114 if (partscan) 1115 loop_reread_partitions(lo); 1116 1117 if (!(mode & BLK_OPEN_EXCL)) 1118 bd_abort_claiming(bdev, loop_configure); 1119 1120 return 0; 1121 1122out_unlock: 1123 loop_global_unlock(lo, is_loop); 1124out_bdev: 1125 if (!(mode & BLK_OPEN_EXCL)) 1126 bd_abort_claiming(bdev, loop_configure); 1127out_putf: 1128 fput(file); 1129 /* This is safe: open() is still holding a reference. */ 1130 module_put(THIS_MODULE); 1131 return error; 1132} 1133 1134static void __loop_clr_fd(struct loop_device *lo, bool release) 1135{ 1136 struct file *filp; 1137 gfp_t gfp = lo->old_gfp_mask; 1138 1139 if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags)) 1140 blk_queue_write_cache(lo->lo_queue, false, false); 1141 1142 /* 1143 * Freeze the request queue when unbinding on a live file descriptor and 1144 * thus an open device. When called from ->release we are guaranteed 1145 * that there is no I/O in progress already. 1146 */ 1147 if (!release) 1148 blk_mq_freeze_queue(lo->lo_queue); 1149 1150 spin_lock_irq(&lo->lo_lock); 1151 filp = lo->lo_backing_file; 1152 lo->lo_backing_file = NULL; 1153 spin_unlock_irq(&lo->lo_lock); 1154 1155 lo->lo_device = NULL; 1156 lo->lo_offset = 0; 1157 lo->lo_sizelimit = 0; 1158 memset(lo->lo_file_name, 0, LO_NAME_SIZE); 1159 loop_reconfigure_limits(lo, 512, false); 1160 invalidate_disk(lo->lo_disk); 1161 loop_sysfs_exit(lo); 1162 /* let user-space know about this change */ 1163 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE); 1164 mapping_set_gfp_mask(filp->f_mapping, gfp); 1165 /* This is safe: open() is still holding a reference. */ 1166 module_put(THIS_MODULE); 1167 if (!release) 1168 blk_mq_unfreeze_queue(lo->lo_queue); 1169 1170 disk_force_media_change(lo->lo_disk); 1171 1172 if (lo->lo_flags & LO_FLAGS_PARTSCAN) { 1173 int err; 1174 1175 /* 1176 * open_mutex has been held already in release path, so don't 1177 * acquire it if this function is called in such case. 1178 * 1179 * If the reread partition isn't from release path, lo_refcnt 1180 * must be at least one and it can only become zero when the 1181 * current holder is released. 1182 */ 1183 if (!release) 1184 mutex_lock(&lo->lo_disk->open_mutex); 1185 err = bdev_disk_changed(lo->lo_disk, false); 1186 if (!release) 1187 mutex_unlock(&lo->lo_disk->open_mutex); 1188 if (err) 1189 pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", 1190 __func__, lo->lo_number, err); 1191 /* Device is gone, no point in returning error */ 1192 } 1193 1194 /* 1195 * lo->lo_state is set to Lo_unbound here after above partscan has 1196 * finished. There cannot be anybody else entering __loop_clr_fd() as 1197 * Lo_rundown state protects us from all the other places trying to 1198 * change the 'lo' device. 1199 */ 1200 lo->lo_flags = 0; 1201 if (!part_shift) 1202 set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); 1203 mutex_lock(&lo->lo_mutex); 1204 lo->lo_state = Lo_unbound; 1205 mutex_unlock(&lo->lo_mutex); 1206 1207 /* 1208 * Need not hold lo_mutex to fput backing file. Calling fput holding 1209 * lo_mutex triggers a circular lock dependency possibility warning as 1210 * fput can take open_mutex which is usually taken before lo_mutex. 1211 */ 1212 fput(filp); 1213} 1214 1215static int loop_clr_fd(struct loop_device *lo) 1216{ 1217 int err; 1218 1219 /* 1220 * Since lo_ioctl() is called without locks held, it is possible that 1221 * loop_configure()/loop_change_fd() and loop_clr_fd() run in parallel. 1222 * 1223 * Therefore, use global lock when setting Lo_rundown state in order to 1224 * make sure that loop_validate_file() will fail if the "struct file" 1225 * which loop_configure()/loop_change_fd() found via fget() was this 1226 * loop device. 1227 */ 1228 err = loop_global_lock_killable(lo, true); 1229 if (err) 1230 return err; 1231 if (lo->lo_state != Lo_bound) { 1232 loop_global_unlock(lo, true); 1233 return -ENXIO; 1234 } 1235 /* 1236 * If we've explicitly asked to tear down the loop device, 1237 * and it has an elevated reference count, set it for auto-teardown when 1238 * the last reference goes away. This stops $!~#$@ udev from 1239 * preventing teardown because it decided that it needs to run blkid on 1240 * the loopback device whenever they appear. xfstests is notorious for 1241 * failing tests because blkid via udev races with a losetup 1242 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d 1243 * command to fail with EBUSY. 1244 */ 1245 if (disk_openers(lo->lo_disk) > 1) { 1246 lo->lo_flags |= LO_FLAGS_AUTOCLEAR; 1247 loop_global_unlock(lo, true); 1248 return 0; 1249 } 1250 lo->lo_state = Lo_rundown; 1251 loop_global_unlock(lo, true); 1252 1253 __loop_clr_fd(lo, false); 1254 return 0; 1255} 1256 1257static int 1258loop_set_status(struct loop_device *lo, const struct loop_info64 *info) 1259{ 1260 int err; 1261 int prev_lo_flags; 1262 bool partscan = false; 1263 bool size_changed = false; 1264 1265 err = mutex_lock_killable(&lo->lo_mutex); 1266 if (err) 1267 return err; 1268 if (lo->lo_state != Lo_bound) { 1269 err = -ENXIO; 1270 goto out_unlock; 1271 } 1272 1273 if (lo->lo_offset != info->lo_offset || 1274 lo->lo_sizelimit != info->lo_sizelimit) { 1275 size_changed = true; 1276 sync_blockdev(lo->lo_device); 1277 invalidate_bdev(lo->lo_device); 1278 } 1279 1280 /* I/O need to be drained during transfer transition */ 1281 blk_mq_freeze_queue(lo->lo_queue); 1282 1283 prev_lo_flags = lo->lo_flags; 1284 1285 err = loop_set_status_from_info(lo, info); 1286 if (err) 1287 goto out_unfreeze; 1288 1289 /* Mask out flags that can't be set using LOOP_SET_STATUS. */ 1290 lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS; 1291 /* For those flags, use the previous values instead */ 1292 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS; 1293 /* For flags that can't be cleared, use previous values too */ 1294 lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS; 1295 1296 if (size_changed) { 1297 loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit, 1298 lo->lo_backing_file); 1299 loop_set_size(lo, new_size); 1300 } 1301 1302 /* update dio if lo_offset or transfer is changed */ 1303 __loop_update_dio(lo, lo->use_dio); 1304 1305out_unfreeze: 1306 blk_mq_unfreeze_queue(lo->lo_queue); 1307 1308 if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) && 1309 !(prev_lo_flags & LO_FLAGS_PARTSCAN)) { 1310 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state); 1311 partscan = true; 1312 } 1313out_unlock: 1314 mutex_unlock(&lo->lo_mutex); 1315 if (partscan) 1316 loop_reread_partitions(lo); 1317 1318 return err; 1319} 1320 1321static int 1322loop_get_status(struct loop_device *lo, struct loop_info64 *info) 1323{ 1324 struct path path; 1325 struct kstat stat; 1326 int ret; 1327 1328 ret = mutex_lock_killable(&lo->lo_mutex); 1329 if (ret) 1330 return ret; 1331 if (lo->lo_state != Lo_bound) { 1332 mutex_unlock(&lo->lo_mutex); 1333 return -ENXIO; 1334 } 1335 1336 memset(info, 0, sizeof(*info)); 1337 info->lo_number = lo->lo_number; 1338 info->lo_offset = lo->lo_offset; 1339 info->lo_sizelimit = lo->lo_sizelimit; 1340 info->lo_flags = lo->lo_flags; 1341 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE); 1342 1343 /* Drop lo_mutex while we call into the filesystem. */ 1344 path = lo->lo_backing_file->f_path; 1345 path_get(&path); 1346 mutex_unlock(&lo->lo_mutex); 1347 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT); 1348 if (!ret) { 1349 info->lo_device = huge_encode_dev(stat.dev); 1350 info->lo_inode = stat.ino; 1351 info->lo_rdevice = huge_encode_dev(stat.rdev); 1352 } 1353 path_put(&path); 1354 return ret; 1355} 1356 1357static void 1358loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64) 1359{ 1360 memset(info64, 0, sizeof(*info64)); 1361 info64->lo_number = info->lo_number; 1362 info64->lo_device = info->lo_device; 1363 info64->lo_inode = info->lo_inode; 1364 info64->lo_rdevice = info->lo_rdevice; 1365 info64->lo_offset = info->lo_offset; 1366 info64->lo_sizelimit = 0; 1367 info64->lo_flags = info->lo_flags; 1368 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE); 1369} 1370 1371static int 1372loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info) 1373{ 1374 memset(info, 0, sizeof(*info)); 1375 info->lo_number = info64->lo_number; 1376 info->lo_device = info64->lo_device; 1377 info->lo_inode = info64->lo_inode; 1378 info->lo_rdevice = info64->lo_rdevice; 1379 info->lo_offset = info64->lo_offset; 1380 info->lo_flags = info64->lo_flags; 1381 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE); 1382 1383 /* error in case values were truncated */ 1384 if (info->lo_device != info64->lo_device || 1385 info->lo_rdevice != info64->lo_rdevice || 1386 info->lo_inode != info64->lo_inode || 1387 info->lo_offset != info64->lo_offset) 1388 return -EOVERFLOW; 1389 1390 return 0; 1391} 1392 1393static int 1394loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg) 1395{ 1396 struct loop_info info; 1397 struct loop_info64 info64; 1398 1399 if (copy_from_user(&info, arg, sizeof (struct loop_info))) 1400 return -EFAULT; 1401 loop_info64_from_old(&info, &info64); 1402 return loop_set_status(lo, &info64); 1403} 1404 1405static int 1406loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg) 1407{ 1408 struct loop_info64 info64; 1409 1410 if (copy_from_user(&info64, arg, sizeof (struct loop_info64))) 1411 return -EFAULT; 1412 return loop_set_status(lo, &info64); 1413} 1414 1415static int 1416loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) { 1417 struct loop_info info; 1418 struct loop_info64 info64; 1419 int err; 1420 1421 if (!arg) 1422 return -EINVAL; 1423 err = loop_get_status(lo, &info64); 1424 if (!err) 1425 err = loop_info64_to_old(&info64, &info); 1426 if (!err && copy_to_user(arg, &info, sizeof(info))) 1427 err = -EFAULT; 1428 1429 return err; 1430} 1431 1432static int 1433loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) { 1434 struct loop_info64 info64; 1435 int err; 1436 1437 if (!arg) 1438 return -EINVAL; 1439 err = loop_get_status(lo, &info64); 1440 if (!err && copy_to_user(arg, &info64, sizeof(info64))) 1441 err = -EFAULT; 1442 1443 return err; 1444} 1445 1446static int loop_set_capacity(struct loop_device *lo) 1447{ 1448 loff_t size; 1449 1450 if (unlikely(lo->lo_state != Lo_bound)) 1451 return -ENXIO; 1452 1453 size = get_loop_size(lo, lo->lo_backing_file); 1454 loop_set_size(lo, size); 1455 1456 return 0; 1457} 1458 1459static int loop_set_dio(struct loop_device *lo, unsigned long arg) 1460{ 1461 int error = -ENXIO; 1462 if (lo->lo_state != Lo_bound) 1463 goto out; 1464 1465 __loop_update_dio(lo, !!arg); 1466 if (lo->use_dio == !!arg) 1467 return 0; 1468 error = -EINVAL; 1469 out: 1470 return error; 1471} 1472 1473static int loop_set_block_size(struct loop_device *lo, unsigned long arg) 1474{ 1475 int err = 0; 1476 1477 if (lo->lo_state != Lo_bound) 1478 return -ENXIO; 1479 1480 err = blk_validate_block_size(arg); 1481 if (err) 1482 return err; 1483 1484 if (lo->lo_queue->limits.logical_block_size == arg) 1485 return 0; 1486 1487 sync_blockdev(lo->lo_device); 1488 invalidate_bdev(lo->lo_device); 1489 1490 blk_mq_freeze_queue(lo->lo_queue); 1491 err = loop_reconfigure_limits(lo, arg, false); 1492 loop_update_dio(lo); 1493 blk_mq_unfreeze_queue(lo->lo_queue); 1494 1495 return err; 1496} 1497 1498static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd, 1499 unsigned long arg) 1500{ 1501 int err; 1502 1503 err = mutex_lock_killable(&lo->lo_mutex); 1504 if (err) 1505 return err; 1506 switch (cmd) { 1507 case LOOP_SET_CAPACITY: 1508 err = loop_set_capacity(lo); 1509 break; 1510 case LOOP_SET_DIRECT_IO: 1511 err = loop_set_dio(lo, arg); 1512 break; 1513 case LOOP_SET_BLOCK_SIZE: 1514 err = loop_set_block_size(lo, arg); 1515 break; 1516 default: 1517 err = -EINVAL; 1518 } 1519 mutex_unlock(&lo->lo_mutex); 1520 return err; 1521} 1522 1523static int lo_ioctl(struct block_device *bdev, blk_mode_t mode, 1524 unsigned int cmd, unsigned long arg) 1525{ 1526 struct loop_device *lo = bdev->bd_disk->private_data; 1527 void __user *argp = (void __user *) arg; 1528 int err; 1529 1530 switch (cmd) { 1531 case LOOP_SET_FD: { 1532 /* 1533 * Legacy case - pass in a zeroed out struct loop_config with 1534 * only the file descriptor set , which corresponds with the 1535 * default parameters we'd have used otherwise. 1536 */ 1537 struct loop_config config; 1538 1539 memset(&config, 0, sizeof(config)); 1540 config.fd = arg; 1541 1542 return loop_configure(lo, mode, bdev, &config); 1543 } 1544 case LOOP_CONFIGURE: { 1545 struct loop_config config; 1546 1547 if (copy_from_user(&config, argp, sizeof(config))) 1548 return -EFAULT; 1549 1550 return loop_configure(lo, mode, bdev, &config); 1551 } 1552 case LOOP_CHANGE_FD: 1553 return loop_change_fd(lo, bdev, arg); 1554 case LOOP_CLR_FD: 1555 return loop_clr_fd(lo); 1556 case LOOP_SET_STATUS: 1557 err = -EPERM; 1558 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) 1559 err = loop_set_status_old(lo, argp); 1560 break; 1561 case LOOP_GET_STATUS: 1562 return loop_get_status_old(lo, argp); 1563 case LOOP_SET_STATUS64: 1564 err = -EPERM; 1565 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN)) 1566 err = loop_set_status64(lo, argp); 1567 break; 1568 case LOOP_GET_STATUS64: 1569 return loop_get_status64(lo, argp); 1570 case LOOP_SET_CAPACITY: 1571 case LOOP_SET_DIRECT_IO: 1572 case LOOP_SET_BLOCK_SIZE: 1573 if (!(mode & BLK_OPEN_WRITE) && !capable(CAP_SYS_ADMIN)) 1574 return -EPERM; 1575 fallthrough; 1576 default: 1577 err = lo_simple_ioctl(lo, cmd, arg); 1578 break; 1579 } 1580 1581 return err; 1582} 1583 1584#ifdef CONFIG_COMPAT 1585struct compat_loop_info { 1586 compat_int_t lo_number; /* ioctl r/o */ 1587 compat_dev_t lo_device; /* ioctl r/o */ 1588 compat_ulong_t lo_inode; /* ioctl r/o */ 1589 compat_dev_t lo_rdevice; /* ioctl r/o */ 1590 compat_int_t lo_offset; 1591 compat_int_t lo_encrypt_type; /* obsolete, ignored */ 1592 compat_int_t lo_encrypt_key_size; /* ioctl w/o */ 1593 compat_int_t lo_flags; /* ioctl r/o */ 1594 char lo_name[LO_NAME_SIZE]; 1595 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */ 1596 compat_ulong_t lo_init[2]; 1597 char reserved[4]; 1598}; 1599 1600/* 1601 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info 1602 * - noinlined to reduce stack space usage in main part of driver 1603 */ 1604static noinline int 1605loop_info64_from_compat(const struct compat_loop_info __user *arg, 1606 struct loop_info64 *info64) 1607{ 1608 struct compat_loop_info info; 1609 1610 if (copy_from_user(&info, arg, sizeof(info))) 1611 return -EFAULT; 1612 1613 memset(info64, 0, sizeof(*info64)); 1614 info64->lo_number = info.lo_number; 1615 info64->lo_device = info.lo_device; 1616 info64->lo_inode = info.lo_inode; 1617 info64->lo_rdevice = info.lo_rdevice; 1618 info64->lo_offset = info.lo_offset; 1619 info64->lo_sizelimit = 0; 1620 info64->lo_flags = info.lo_flags; 1621 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE); 1622 return 0; 1623} 1624 1625/* 1626 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace 1627 * - noinlined to reduce stack space usage in main part of driver 1628 */ 1629static noinline int 1630loop_info64_to_compat(const struct loop_info64 *info64, 1631 struct compat_loop_info __user *arg) 1632{ 1633 struct compat_loop_info info; 1634 1635 memset(&info, 0, sizeof(info)); 1636 info.lo_number = info64->lo_number; 1637 info.lo_device = info64->lo_device; 1638 info.lo_inode = info64->lo_inode; 1639 info.lo_rdevice = info64->lo_rdevice; 1640 info.lo_offset = info64->lo_offset; 1641 info.lo_flags = info64->lo_flags; 1642 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE); 1643 1644 /* error in case values were truncated */ 1645 if (info.lo_device != info64->lo_device || 1646 info.lo_rdevice != info64->lo_rdevice || 1647 info.lo_inode != info64->lo_inode || 1648 info.lo_offset != info64->lo_offset) 1649 return -EOVERFLOW; 1650 1651 if (copy_to_user(arg, &info, sizeof(info))) 1652 return -EFAULT; 1653 return 0; 1654} 1655 1656static int 1657loop_set_status_compat(struct loop_device *lo, 1658 const struct compat_loop_info __user *arg) 1659{ 1660 struct loop_info64 info64; 1661 int ret; 1662 1663 ret = loop_info64_from_compat(arg, &info64); 1664 if (ret < 0) 1665 return ret; 1666 return loop_set_status(lo, &info64); 1667} 1668 1669static int 1670loop_get_status_compat(struct loop_device *lo, 1671 struct compat_loop_info __user *arg) 1672{ 1673 struct loop_info64 info64; 1674 int err; 1675 1676 if (!arg) 1677 return -EINVAL; 1678 err = loop_get_status(lo, &info64); 1679 if (!err) 1680 err = loop_info64_to_compat(&info64, arg); 1681 return err; 1682} 1683 1684static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode, 1685 unsigned int cmd, unsigned long arg) 1686{ 1687 struct loop_device *lo = bdev->bd_disk->private_data; 1688 int err; 1689 1690 switch(cmd) { 1691 case LOOP_SET_STATUS: 1692 err = loop_set_status_compat(lo, 1693 (const struct compat_loop_info __user *)arg); 1694 break; 1695 case LOOP_GET_STATUS: 1696 err = loop_get_status_compat(lo, 1697 (struct compat_loop_info __user *)arg); 1698 break; 1699 case LOOP_SET_CAPACITY: 1700 case LOOP_CLR_FD: 1701 case LOOP_GET_STATUS64: 1702 case LOOP_SET_STATUS64: 1703 case LOOP_CONFIGURE: 1704 arg = (unsigned long) compat_ptr(arg); 1705 fallthrough; 1706 case LOOP_SET_FD: 1707 case LOOP_CHANGE_FD: 1708 case LOOP_SET_BLOCK_SIZE: 1709 case LOOP_SET_DIRECT_IO: 1710 err = lo_ioctl(bdev, mode, cmd, arg); 1711 break; 1712 default: 1713 err = -ENOIOCTLCMD; 1714 break; 1715 } 1716 return err; 1717} 1718#endif 1719 1720static void lo_release(struct gendisk *disk) 1721{ 1722 struct loop_device *lo = disk->private_data; 1723 1724 if (disk_openers(disk) > 0) 1725 return; 1726 1727 mutex_lock(&lo->lo_mutex); 1728 if (lo->lo_state == Lo_bound && (lo->lo_flags & LO_FLAGS_AUTOCLEAR)) { 1729 lo->lo_state = Lo_rundown; 1730 mutex_unlock(&lo->lo_mutex); 1731 /* 1732 * In autoclear mode, stop the loop thread 1733 * and remove configuration after last close. 1734 */ 1735 __loop_clr_fd(lo, true); 1736 return; 1737 } 1738 mutex_unlock(&lo->lo_mutex); 1739} 1740 1741static void lo_free_disk(struct gendisk *disk) 1742{ 1743 struct loop_device *lo = disk->private_data; 1744 1745 if (lo->workqueue) 1746 destroy_workqueue(lo->workqueue); 1747 loop_free_idle_workers(lo, true); 1748 timer_shutdown_sync(&lo->timer); 1749 mutex_destroy(&lo->lo_mutex); 1750 kfree(lo); 1751} 1752 1753static const struct block_device_operations lo_fops = { 1754 .owner = THIS_MODULE, 1755 .release = lo_release, 1756 .ioctl = lo_ioctl, 1757#ifdef CONFIG_COMPAT 1758 .compat_ioctl = lo_compat_ioctl, 1759#endif 1760 .free_disk = lo_free_disk, 1761}; 1762 1763/* 1764 * And now the modules code and kernel interface. 1765 */ 1766 1767/* 1768 * If max_loop is specified, create that many devices upfront. 1769 * This also becomes a hard limit. If max_loop is not specified, 1770 * the default isn't a hard limit (as before commit 85c50197716c 1771 * changed the default value from 0 for max_loop=0 reasons), just 1772 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module 1773 * init time. Loop devices can be requested on-demand with the 1774 * /dev/loop-control interface, or be instantiated by accessing 1775 * a 'dead' device node. 1776 */ 1777static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT; 1778 1779#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD 1780static bool max_loop_specified; 1781 1782static int max_loop_param_set_int(const char *val, 1783 const struct kernel_param *kp) 1784{ 1785 int ret; 1786 1787 ret = param_set_int(val, kp); 1788 if (ret < 0) 1789 return ret; 1790 1791 max_loop_specified = true; 1792 return 0; 1793} 1794 1795static const struct kernel_param_ops max_loop_param_ops = { 1796 .set = max_loop_param_set_int, 1797 .get = param_get_int, 1798}; 1799 1800module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444); 1801MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); 1802#else 1803module_param(max_loop, int, 0444); 1804MODULE_PARM_DESC(max_loop, "Initial number of loop devices"); 1805#endif 1806 1807module_param(max_part, int, 0444); 1808MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); 1809 1810static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH; 1811 1812static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p) 1813{ 1814 int qd, ret; 1815 1816 ret = kstrtoint(s, 0, &qd); 1817 if (ret < 0) 1818 return ret; 1819 if (qd < 1) 1820 return -EINVAL; 1821 hw_queue_depth = qd; 1822 return 0; 1823} 1824 1825static const struct kernel_param_ops loop_hw_qdepth_param_ops = { 1826 .set = loop_set_hw_queue_depth, 1827 .get = param_get_int, 1828}; 1829 1830device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444); 1831MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH)); 1832 1833MODULE_LICENSE("GPL"); 1834MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); 1835 1836static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx, 1837 const struct blk_mq_queue_data *bd) 1838{ 1839 struct request *rq = bd->rq; 1840 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq); 1841 struct loop_device *lo = rq->q->queuedata; 1842 1843 blk_mq_start_request(rq); 1844 1845 if (lo->lo_state != Lo_bound) 1846 return BLK_STS_IOERR; 1847 1848 switch (req_op(rq)) { 1849 case REQ_OP_FLUSH: 1850 case REQ_OP_DISCARD: 1851 case REQ_OP_WRITE_ZEROES: 1852 cmd->use_aio = false; 1853 break; 1854 default: 1855 cmd->use_aio = lo->use_dio; 1856 break; 1857 } 1858 1859 /* always use the first bio's css */ 1860 cmd->blkcg_css = NULL; 1861 cmd->memcg_css = NULL; 1862#ifdef CONFIG_BLK_CGROUP 1863 if (rq->bio) { 1864 cmd->blkcg_css = bio_blkcg_css(rq->bio); 1865#ifdef CONFIG_MEMCG 1866 if (cmd->blkcg_css) { 1867 cmd->memcg_css = 1868 cgroup_get_e_css(cmd->blkcg_css->cgroup, 1869 &memory_cgrp_subsys); 1870 } 1871#endif 1872 } 1873#endif 1874 loop_queue_work(lo, cmd); 1875 1876 return BLK_STS_OK; 1877} 1878 1879static void loop_handle_cmd(struct loop_cmd *cmd) 1880{ 1881 struct cgroup_subsys_state *cmd_blkcg_css = cmd->blkcg_css; 1882 struct cgroup_subsys_state *cmd_memcg_css = cmd->memcg_css; 1883 struct request *rq = blk_mq_rq_from_pdu(cmd); 1884 const bool write = op_is_write(req_op(rq)); 1885 struct loop_device *lo = rq->q->queuedata; 1886 int ret = 0; 1887 struct mem_cgroup *old_memcg = NULL; 1888 const bool use_aio = cmd->use_aio; 1889 1890 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { 1891 ret = -EIO; 1892 goto failed; 1893 } 1894 1895 if (cmd_blkcg_css) 1896 kthread_associate_blkcg(cmd_blkcg_css); 1897 if (cmd_memcg_css) 1898 old_memcg = set_active_memcg( 1899 mem_cgroup_from_css(cmd_memcg_css)); 1900 1901 /* 1902 * do_req_filebacked() may call blk_mq_complete_request() synchronously 1903 * or asynchronously if using aio. Hence, do not touch 'cmd' after 1904 * do_req_filebacked() has returned unless we are sure that 'cmd' has 1905 * not yet been completed. 1906 */ 1907 ret = do_req_filebacked(lo, rq); 1908 1909 if (cmd_blkcg_css) 1910 kthread_associate_blkcg(NULL); 1911 1912 if (cmd_memcg_css) { 1913 set_active_memcg(old_memcg); 1914 css_put(cmd_memcg_css); 1915 } 1916 failed: 1917 /* complete non-aio request */ 1918 if (!use_aio || ret) { 1919 if (ret == -EOPNOTSUPP) 1920 cmd->ret = ret; 1921 else 1922 cmd->ret = ret ? -EIO : 0; 1923 if (likely(!blk_should_fake_timeout(rq->q))) 1924 blk_mq_complete_request(rq); 1925 } 1926} 1927 1928static void loop_process_work(struct loop_worker *worker, 1929 struct list_head *cmd_list, struct loop_device *lo) 1930{ 1931 int orig_flags = current->flags; 1932 struct loop_cmd *cmd; 1933 1934 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; 1935 spin_lock_irq(&lo->lo_work_lock); 1936 while (!list_empty(cmd_list)) { 1937 cmd = container_of( 1938 cmd_list->next, struct loop_cmd, list_entry); 1939 list_del(cmd_list->next); 1940 spin_unlock_irq(&lo->lo_work_lock); 1941 1942 loop_handle_cmd(cmd); 1943 cond_resched(); 1944 1945 spin_lock_irq(&lo->lo_work_lock); 1946 } 1947 1948 /* 1949 * We only add to the idle list if there are no pending cmds 1950 * *and* the worker will not run again which ensures that it 1951 * is safe to free any worker on the idle list 1952 */ 1953 if (worker && !work_pending(&worker->work)) { 1954 worker->last_ran_at = jiffies; 1955 list_add_tail(&worker->idle_list, &lo->idle_worker_list); 1956 loop_set_timer(lo); 1957 } 1958 spin_unlock_irq(&lo->lo_work_lock); 1959 current->flags = orig_flags; 1960} 1961 1962static void loop_workfn(struct work_struct *work) 1963{ 1964 struct loop_worker *worker = 1965 container_of(work, struct loop_worker, work); 1966 loop_process_work(worker, &worker->cmd_list, worker->lo); 1967} 1968 1969static void loop_rootcg_workfn(struct work_struct *work) 1970{ 1971 struct loop_device *lo = 1972 container_of(work, struct loop_device, rootcg_work); 1973 loop_process_work(NULL, &lo->rootcg_cmd_list, lo); 1974} 1975 1976static const struct blk_mq_ops loop_mq_ops = { 1977 .queue_rq = loop_queue_rq, 1978 .complete = lo_complete_rq, 1979}; 1980 1981static int loop_add(int i) 1982{ 1983 struct queue_limits lim = { 1984 /* 1985 * Random number picked from the historic block max_sectors cap. 1986 */ 1987 .max_hw_sectors = 2560u, 1988 }; 1989 struct loop_device *lo; 1990 struct gendisk *disk; 1991 int err; 1992 1993 err = -ENOMEM; 1994 lo = kzalloc(sizeof(*lo), GFP_KERNEL); 1995 if (!lo) 1996 goto out; 1997 lo->worker_tree = RB_ROOT; 1998 INIT_LIST_HEAD(&lo->idle_worker_list); 1999 timer_setup(&lo->timer, loop_free_idle_workers_timer, TIMER_DEFERRABLE); 2000 lo->lo_state = Lo_unbound; 2001 2002 err = mutex_lock_killable(&loop_ctl_mutex); 2003 if (err) 2004 goto out_free_dev; 2005 2006 /* allocate id, if @id >= 0, we're requesting that specific id */ 2007 if (i >= 0) { 2008 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL); 2009 if (err == -ENOSPC) 2010 err = -EEXIST; 2011 } else { 2012 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL); 2013 } 2014 mutex_unlock(&loop_ctl_mutex); 2015 if (err < 0) 2016 goto out_free_dev; 2017 i = err; 2018 2019 lo->tag_set.ops = &loop_mq_ops; 2020 lo->tag_set.nr_hw_queues = 1; 2021 lo->tag_set.queue_depth = hw_queue_depth; 2022 lo->tag_set.numa_node = NUMA_NO_NODE; 2023 lo->tag_set.cmd_size = sizeof(struct loop_cmd); 2024 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING | 2025 BLK_MQ_F_NO_SCHED_BY_DEFAULT; 2026 lo->tag_set.driver_data = lo; 2027 2028 err = blk_mq_alloc_tag_set(&lo->tag_set); 2029 if (err) 2030 goto out_free_idr; 2031 2032 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo); 2033 if (IS_ERR(disk)) { 2034 err = PTR_ERR(disk); 2035 goto out_cleanup_tags; 2036 } 2037 lo->lo_queue = lo->lo_disk->queue; 2038 2039 /* 2040 * By default, we do buffer IO, so it doesn't make sense to enable 2041 * merge because the I/O submitted to backing file is handled page by 2042 * page. For directio mode, merge does help to dispatch bigger request 2043 * to underlayer disk. We will enable merge once directio is enabled. 2044 */ 2045 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue); 2046 2047 /* 2048 * Disable partition scanning by default. The in-kernel partition 2049 * scanning can be requested individually per-device during its 2050 * setup. Userspace can always add and remove partitions from all 2051 * devices. The needed partition minors are allocated from the 2052 * extended minor space, the main loop device numbers will continue 2053 * to match the loop minors, regardless of the number of partitions 2054 * used. 2055 * 2056 * If max_part is given, partition scanning is globally enabled for 2057 * all loop devices. The minors for the main loop devices will be 2058 * multiples of max_part. 2059 * 2060 * Note: Global-for-all-devices, set-only-at-init, read-only module 2061 * parameteters like 'max_loop' and 'max_part' make things needlessly 2062 * complicated, are too static, inflexible and may surprise 2063 * userspace tools. Parameters like this in general should be avoided. 2064 */ 2065 if (!part_shift) 2066 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state); 2067 mutex_init(&lo->lo_mutex); 2068 lo->lo_number = i; 2069 spin_lock_init(&lo->lo_lock); 2070 spin_lock_init(&lo->lo_work_lock); 2071 INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn); 2072 INIT_LIST_HEAD(&lo->rootcg_cmd_list); 2073 disk->major = LOOP_MAJOR; 2074 disk->first_minor = i << part_shift; 2075 disk->minors = 1 << part_shift; 2076 disk->fops = &lo_fops; 2077 disk->private_data = lo; 2078 disk->queue = lo->lo_queue; 2079 disk->events = DISK_EVENT_MEDIA_CHANGE; 2080 disk->event_flags = DISK_EVENT_FLAG_UEVENT; 2081 sprintf(disk->disk_name, "loop%d", i); 2082 /* Make this loop device reachable from pathname. */ 2083 err = add_disk(disk); 2084 if (err) 2085 goto out_cleanup_disk; 2086 2087 /* Show this loop device. */ 2088 mutex_lock(&loop_ctl_mutex); 2089 lo->idr_visible = true; 2090 mutex_unlock(&loop_ctl_mutex); 2091 2092 return i; 2093 2094out_cleanup_disk: 2095 put_disk(disk); 2096out_cleanup_tags: 2097 blk_mq_free_tag_set(&lo->tag_set); 2098out_free_idr: 2099 mutex_lock(&loop_ctl_mutex); 2100 idr_remove(&loop_index_idr, i); 2101 mutex_unlock(&loop_ctl_mutex); 2102out_free_dev: 2103 kfree(lo); 2104out: 2105 return err; 2106} 2107 2108static void loop_remove(struct loop_device *lo) 2109{ 2110 /* Make this loop device unreachable from pathname. */ 2111 del_gendisk(lo->lo_disk); 2112 blk_mq_free_tag_set(&lo->tag_set); 2113 2114 mutex_lock(&loop_ctl_mutex); 2115 idr_remove(&loop_index_idr, lo->lo_number); 2116 mutex_unlock(&loop_ctl_mutex); 2117 2118 put_disk(lo->lo_disk); 2119} 2120 2121#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD 2122static void loop_probe(dev_t dev) 2123{ 2124 int idx = MINOR(dev) >> part_shift; 2125 2126 if (max_loop_specified && max_loop && idx >= max_loop) 2127 return; 2128 loop_add(idx); 2129} 2130#else 2131#define loop_probe NULL 2132#endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */ 2133 2134static int loop_control_remove(int idx) 2135{ 2136 struct loop_device *lo; 2137 int ret; 2138 2139 if (idx < 0) { 2140 pr_warn_once("deleting an unspecified loop device is not supported.\n"); 2141 return -EINVAL; 2142 } 2143 2144 /* Hide this loop device for serialization. */ 2145 ret = mutex_lock_killable(&loop_ctl_mutex); 2146 if (ret) 2147 return ret; 2148 lo = idr_find(&loop_index_idr, idx); 2149 if (!lo || !lo->idr_visible) 2150 ret = -ENODEV; 2151 else 2152 lo->idr_visible = false; 2153 mutex_unlock(&loop_ctl_mutex); 2154 if (ret) 2155 return ret; 2156 2157 /* Check whether this loop device can be removed. */ 2158 ret = mutex_lock_killable(&lo->lo_mutex); 2159 if (ret) 2160 goto mark_visible; 2161 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) { 2162 mutex_unlock(&lo->lo_mutex); 2163 ret = -EBUSY; 2164 goto mark_visible; 2165 } 2166 /* Mark this loop device as no more bound, but not quite unbound yet */ 2167 lo->lo_state = Lo_deleting; 2168 mutex_unlock(&lo->lo_mutex); 2169 2170 loop_remove(lo); 2171 return 0; 2172 2173mark_visible: 2174 /* Show this loop device again. */ 2175 mutex_lock(&loop_ctl_mutex); 2176 lo->idr_visible = true; 2177 mutex_unlock(&loop_ctl_mutex); 2178 return ret; 2179} 2180 2181static int loop_control_get_free(int idx) 2182{ 2183 struct loop_device *lo; 2184 int id, ret; 2185 2186 ret = mutex_lock_killable(&loop_ctl_mutex); 2187 if (ret) 2188 return ret; 2189 idr_for_each_entry(&loop_index_idr, lo, id) { 2190 /* Hitting a race results in creating a new loop device which is harmless. */ 2191 if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound) 2192 goto found; 2193 } 2194 mutex_unlock(&loop_ctl_mutex); 2195 return loop_add(-1); 2196found: 2197 mutex_unlock(&loop_ctl_mutex); 2198 return id; 2199} 2200 2201static long loop_control_ioctl(struct file *file, unsigned int cmd, 2202 unsigned long parm) 2203{ 2204 switch (cmd) { 2205 case LOOP_CTL_ADD: 2206 return loop_add(parm); 2207 case LOOP_CTL_REMOVE: 2208 return loop_control_remove(parm); 2209 case LOOP_CTL_GET_FREE: 2210 return loop_control_get_free(parm); 2211 default: 2212 return -ENOSYS; 2213 } 2214} 2215 2216static const struct file_operations loop_ctl_fops = { 2217 .open = nonseekable_open, 2218 .unlocked_ioctl = loop_control_ioctl, 2219 .compat_ioctl = loop_control_ioctl, 2220 .owner = THIS_MODULE, 2221 .llseek = noop_llseek, 2222}; 2223 2224static struct miscdevice loop_misc = { 2225 .minor = LOOP_CTRL_MINOR, 2226 .name = "loop-control", 2227 .fops = &loop_ctl_fops, 2228}; 2229 2230MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR); 2231MODULE_ALIAS("devname:loop-control"); 2232 2233static int __init loop_init(void) 2234{ 2235 int i; 2236 int err; 2237 2238 part_shift = 0; 2239 if (max_part > 0) { 2240 part_shift = fls(max_part); 2241 2242 /* 2243 * Adjust max_part according to part_shift as it is exported 2244 * to user space so that user can decide correct minor number 2245 * if [s]he want to create more devices. 2246 * 2247 * Note that -1 is required because partition 0 is reserved 2248 * for the whole disk. 2249 */ 2250 max_part = (1UL << part_shift) - 1; 2251 } 2252 2253 if ((1UL << part_shift) > DISK_MAX_PARTS) { 2254 err = -EINVAL; 2255 goto err_out; 2256 } 2257 2258 if (max_loop > 1UL << (MINORBITS - part_shift)) { 2259 err = -EINVAL; 2260 goto err_out; 2261 } 2262 2263 err = misc_register(&loop_misc); 2264 if (err < 0) 2265 goto err_out; 2266 2267 2268 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) { 2269 err = -EIO; 2270 goto misc_out; 2271 } 2272 2273 /* pre-create number of devices given by config or max_loop */ 2274 for (i = 0; i < max_loop; i++) 2275 loop_add(i); 2276 2277 printk(KERN_INFO "loop: module loaded\n"); 2278 return 0; 2279 2280misc_out: 2281 misc_deregister(&loop_misc); 2282err_out: 2283 return err; 2284} 2285 2286static void __exit loop_exit(void) 2287{ 2288 struct loop_device *lo; 2289 int id; 2290 2291 unregister_blkdev(LOOP_MAJOR, "loop"); 2292 misc_deregister(&loop_misc); 2293 2294 /* 2295 * There is no need to use loop_ctl_mutex here, for nobody else can 2296 * access loop_index_idr when this module is unloading (unless forced 2297 * module unloading is requested). If this is not a clean unloading, 2298 * we have no means to avoid kernel crash. 2299 */ 2300 idr_for_each_entry(&loop_index_idr, lo, id) 2301 loop_remove(lo); 2302 2303 idr_destroy(&loop_index_idr); 2304} 2305 2306module_init(loop_init); 2307module_exit(loop_exit); 2308 2309#ifndef MODULE 2310static int __init max_loop_setup(char *str) 2311{ 2312 max_loop = simple_strtol(str, NULL, 0); 2313#ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD 2314 max_loop_specified = true; 2315#endif 2316 return 1; 2317} 2318 2319__setup("max_loop=", max_loop_setup); 2320#endif 2321