1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright 1993 by Theodore Ts'o.
5 #include <linux/module.h>
6 #include <linux/moduleparam.h>
7 #include <linux/sched.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>
40 /* Possible states of device */
48 struct loop_func_table;
55 char lo_file_name[LO_NAME_SIZE];
57 struct file * lo_backing_file;
58 struct block_device *lo_device;
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;
74 struct request_queue *lo_queue;
75 struct blk_mq_tag_set tag_set;
76 struct gendisk *lo_disk;
77 struct mutex lo_mutex;
82 struct list_head list_entry;
83 bool use_aio; /* use AIO interface to handle I/O */
84 atomic_t ref; /* only for aio */
88 struct cgroup_subsys_state *blkcg_css;
89 struct cgroup_subsys_state *memcg_css;
92 #define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
93 #define LOOP_DEFAULT_HW_Q_DEPTH 128
95 static DEFINE_IDR(loop_index_idr);
96 static DEFINE_MUTEX(loop_ctl_mutex);
97 static DEFINE_MUTEX(loop_validate_mutex);
100 * loop_global_lock_killable() - take locks for safe loop_validate_file() test
102 * @lo: struct loop_device
103 * @global: true if @lo is about to bind another "struct loop_device", false otherwise
105 * Returns 0 on success, -EINTR otherwise.
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.
111 static int loop_global_lock_killable(struct loop_device *lo, bool global)
116 err = mutex_lock_killable(&loop_validate_mutex);
120 err = mutex_lock_killable(&lo->lo_mutex);
122 mutex_unlock(&loop_validate_mutex);
127 * loop_global_unlock() - release locks taken by loop_global_lock_killable()
129 * @lo: struct loop_device
130 * @global: true if @lo was about to bind another "struct loop_device", false otherwise
132 static void loop_global_unlock(struct loop_device *lo, bool global)
134 mutex_unlock(&lo->lo_mutex);
136 mutex_unlock(&loop_validate_mutex);
140 static int part_shift;
142 static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
146 /* Compute loopsize in bytes */
147 loopsize = i_size_read(file->f_mapping->host);
150 /* offset is beyond i_size, weird but possible */
154 if (sizelimit > 0 && sizelimit < loopsize)
155 loopsize = sizelimit;
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.
160 return loopsize >> 9;
163 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
165 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
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.
173 static bool lo_bdev_can_use_dio(struct loop_device *lo,
174 struct block_device *backing_bdev)
176 unsigned short sb_bsize = bdev_logical_block_size(backing_bdev);
178 if (queue_logical_block_size(lo->lo_queue) < sb_bsize)
180 if (lo->lo_offset & (sb_bsize - 1))
185 static void __loop_update_dio(struct loop_device *lo, bool dio)
187 struct file *file = lo->lo_backing_file;
188 struct inode *inode = file->f_mapping->host;
189 struct block_device *backing_bdev = NULL;
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;
197 use_dio = dio && (file->f_mode & FMODE_CAN_ODIRECT) &&
198 (!backing_bdev || lo_bdev_can_use_dio(lo, backing_bdev));
200 if (lo->use_dio == use_dio)
203 /* flush dirty pages before changing direct IO */
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)
211 if (lo->lo_state == Lo_bound)
212 blk_mq_freeze_queue(lo->lo_queue);
213 lo->use_dio = use_dio;
215 blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
216 lo->lo_flags |= LO_FLAGS_DIRECT_IO;
218 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
219 lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
221 if (lo->lo_state == Lo_bound)
222 blk_mq_unfreeze_queue(lo->lo_queue);
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
230 * Callers must validate that the size passed into this function fits into
231 * a sector_t, eg using loop_validate_size()
233 static void loop_set_size(struct loop_device *lo, loff_t size)
235 if (!set_capacity_and_notify(lo->lo_disk, size))
236 kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
239 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
244 iov_iter_bvec(&i, ITER_SOURCE, bvec, 1, bvec->bv_len);
246 bw = vfs_iter_write(file, &i, ppos, 0);
248 if (likely(bw == bvec->bv_len))
251 printk_ratelimited(KERN_ERR
252 "loop: Write error at byte offset %llu, length %i.\n",
253 (unsigned long long)*ppos, bvec->bv_len);
259 static int lo_write_simple(struct loop_device *lo, struct request *rq,
263 struct req_iterator iter;
266 rq_for_each_segment(bvec, rq, iter) {
267 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
276 static int lo_read_simple(struct loop_device *lo, struct request *rq,
280 struct req_iterator iter;
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);
290 flush_dcache_page(bvec.bv_page);
292 if (len != bvec.bv_len) {
295 __rq_for_each_bio(bio, rq)
305 static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
309 * We use fallocate to manipulate the space mappings used by the image
310 * a.k.a. discard/zerorange.
312 struct file *file = lo->lo_backing_file;
315 mode |= FALLOC_FL_KEEP_SIZE;
317 if (!bdev_max_discard_sectors(lo->lo_device))
320 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
321 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
326 static int lo_req_flush(struct loop_device *lo, struct request *rq)
328 int ret = vfs_fsync(lo->lo_backing_file, 0);
329 if (unlikely(ret && ret != -EINVAL))
335 static void lo_complete_rq(struct request *rq)
337 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
338 blk_status_t ret = BLK_STS_OK;
340 if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
341 req_op(rq) != REQ_OP_READ) {
343 ret = errno_to_blk_status(cmd->ret);
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.
352 blk_update_request(rq, BLK_STS_OK, cmd->ret);
354 blk_mq_requeue_request(rq, true);
357 struct bio *bio = rq->bio;
366 blk_mq_end_request(rq, ret);
370 static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
372 struct request *rq = blk_mq_rq_from_pdu(cmd);
374 if (!atomic_dec_and_test(&cmd->ref))
378 if (likely(!blk_should_fake_timeout(rq->q)))
379 blk_mq_complete_request(rq);
382 static void lo_rw_aio_complete(struct kiocb *iocb, long ret)
384 struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
387 lo_rw_aio_do_completion(cmd);
390 static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
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;
404 rq_for_each_bvec(tmp, rq, rq_iter)
407 if (rq->bio != rq->biotail) {
409 bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
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.
421 rq_for_each_bvec(tmp, rq, rq_iter) {
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
433 offset = bio->bi_iter.bi_bvec_done;
434 bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
436 atomic_set(&cmd->ref, 2);
438 iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
439 iter.iov_offset = offset;
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);
447 if (rw == ITER_SOURCE)
448 ret = call_write_iter(file, &cmd->iocb, &iter);
450 ret = call_read_iter(file, &cmd->iocb, &iter);
452 lo_rw_aio_do_completion(cmd);
454 if (ret != -EIOCBQUEUED)
455 lo_rw_aio_complete(&cmd->iocb, ret);
459 static int do_req_filebacked(struct loop_device *lo, struct request *rq)
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;
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().
473 switch (req_op(rq)) {
475 return lo_req_flush(lo, rq);
476 case REQ_OP_WRITE_ZEROES:
478 * If the caller doesn't want deallocation, call zeroout to
479 * write zeroes the range. Otherwise, punch them out.
481 return lo_fallocate(lo, rq, pos,
482 (rq->cmd_flags & REQ_NOUNMAP) ?
483 FALLOC_FL_ZERO_RANGE :
484 FALLOC_FL_PUNCH_HOLE);
486 return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
489 return lo_rw_aio(lo, cmd, pos, ITER_SOURCE);
491 return lo_write_simple(lo, rq, pos);
494 return lo_rw_aio(lo, cmd, pos, ITER_DEST);
496 return lo_read_simple(lo, rq, pos);
503 static inline void loop_update_dio(struct loop_device *lo)
505 __loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
509 static void loop_reread_partitions(struct loop_device *lo)
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);
517 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
518 __func__, lo->lo_number, lo->lo_file_name, rc);
521 static inline int is_loop_device(struct file *file)
523 struct inode *i = file->f_mapping->host;
525 return i && S_ISBLK(i->i_mode) && imajor(i) == LOOP_MAJOR;
528 static int loop_validate_file(struct file *file, struct block_device *bdev)
530 struct inode *inode = file->f_mapping->host;
531 struct file *f = file;
533 /* Avoid recursion */
534 while (is_loop_device(f)) {
535 struct loop_device *l;
537 lockdep_assert_held(&loop_validate_mutex);
538 if (f->f_mapping->host->i_rdev == bdev->bd_dev)
541 l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
542 if (l->lo_state != Lo_bound)
544 /* Order wrt setting lo->lo_backing_file in loop_configure(). */
546 f = l->lo_backing_file;
548 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
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.
561 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
564 struct file *file = fget(arg);
565 struct file *old_file;
573 /* suppress uevents while reconfiguring the device */
574 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
576 is_loop = is_loop_device(file);
577 error = loop_global_lock_killable(lo, is_loop);
581 if (lo->lo_state != Lo_bound)
584 /* the loop device has to be read-only */
586 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
589 error = loop_validate_file(file, bdev);
593 old_file = lo->lo_backing_file;
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))
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));
610 blk_mq_unfreeze_queue(lo->lo_queue);
611 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
612 loop_global_unlock(lo, is_loop);
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.
619 mutex_lock(&loop_validate_mutex);
620 mutex_unlock(&loop_validate_mutex);
623 * We must drop file reference outside of lo_mutex as dropping
624 * the file ref can take open_mutex which creates circular locking
629 loop_reread_partitions(lo);
633 /* enable and uncork uevent now that we are done */
634 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
638 loop_global_unlock(lo, is_loop);
644 /* loop sysfs attributes */
646 static ssize_t loop_attr_show(struct device *dev, char *page,
647 ssize_t (*callback)(struct loop_device *, char *))
649 struct gendisk *disk = dev_to_disk(dev);
650 struct loop_device *lo = disk->private_data;
652 return callback(lo, page);
655 #define LOOP_ATTR_RO(_name) \
656 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
657 static ssize_t loop_attr_do_show_##_name(struct device *d, \
658 struct device_attribute *attr, char *b) \
660 return loop_attr_show(d, b, loop_attr_##_name##_show); \
662 static struct device_attribute loop_attr_##_name = \
663 __ATTR(_name, 0444, loop_attr_do_show_##_name, NULL);
665 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
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);
675 if (IS_ERR_OR_NULL(p))
679 memmove(buf, p, ret);
687 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
689 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
692 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
694 return sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
697 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
699 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
701 return sysfs_emit(buf, "%s\n", autoclear ? "1" : "0");
704 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
706 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
708 return sysfs_emit(buf, "%s\n", partscan ? "1" : "0");
711 static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
713 int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
715 return sysfs_emit(buf, "%s\n", dio ? "1" : "0");
718 LOOP_ATTR_RO(backing_file);
719 LOOP_ATTR_RO(offset);
720 LOOP_ATTR_RO(sizelimit);
721 LOOP_ATTR_RO(autoclear);
722 LOOP_ATTR_RO(partscan);
725 static 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,
735 static struct attribute_group loop_attribute_group = {
740 static void loop_sysfs_init(struct loop_device *lo)
742 lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
743 &loop_attribute_group);
746 static void loop_sysfs_exit(struct loop_device *lo)
748 if (lo->sysfs_inited)
749 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
750 &loop_attribute_group);
753 static void loop_config_discard(struct loop_device *lo,
754 struct queue_limits *lim)
756 struct file *file = lo->lo_backing_file;
757 struct inode *inode = file->f_mapping->host;
758 u32 granularity = 0, max_discard_sectors = 0;
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.
768 if (S_ISBLK(inode->i_mode)) {
769 struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
771 max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
772 granularity = bdev_discard_granularity(I_BDEV(inode)) ?:
773 queue_physical_block_size(backingq);
776 * We use punch hole to reclaim the free space used by the
777 * image a.k.a. discard.
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;
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;
789 lim->discard_granularity = 0;
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;
802 static void loop_workfn(struct work_struct *work);
804 #ifdef CONFIG_BLK_CGROUP
805 static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
807 return !css || css == blkcg_root_css;
810 static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
816 static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
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;
823 spin_lock_irq(&lo->lo_work_lock);
825 if (queue_on_root_worker(cmd->blkcg_css))
828 node = &lo->worker_tree.rb_node;
832 cur_worker = container_of(*node, struct loop_worker, rb_node);
833 if (cur_worker->blkcg_css == cmd->blkcg_css) {
836 } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
837 node = &(*node)->rb_left;
839 node = &(*node)->rb_right;
845 worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
847 * In the event we cannot allocate a worker, just queue on the
848 * rootcg worker and issue the I/O as the rootcg
851 cmd->blkcg_css = NULL;
853 css_put(cmd->memcg_css);
854 cmd->memcg_css = NULL;
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);
864 rb_link_node(&worker->rb_node, parent, node);
865 rb_insert_color(&worker->rb_node, &lo->worker_tree);
869 * We need to remove from the idle list here while
870 * holding the lock so that the idle timer doesn't
873 if (!list_empty(&worker->idle_list))
874 list_del_init(&worker->idle_list);
875 work = &worker->work;
876 cmd_list = &worker->cmd_list;
878 work = &lo->rootcg_work;
879 cmd_list = &lo->rootcg_cmd_list;
881 list_add_tail(&cmd->list_entry, cmd_list);
882 queue_work(lo->workqueue, work);
883 spin_unlock_irq(&lo->lo_work_lock);
886 static void loop_set_timer(struct loop_device *lo)
888 timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
891 static void loop_free_idle_workers(struct loop_device *lo, bool delete_all)
893 struct loop_worker *pos, *worker;
895 spin_lock_irq(&lo->lo_work_lock);
896 list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
899 time_is_after_jiffies(worker->last_ran_at +
900 LOOP_IDLE_WORKER_TIMEOUT))
902 list_del(&worker->idle_list);
903 rb_erase(&worker->rb_node, &lo->worker_tree);
904 css_put(worker->blkcg_css);
907 if (!list_empty(&lo->idle_worker_list))
909 spin_unlock_irq(&lo->lo_work_lock);
912 static void loop_free_idle_workers_timer(struct timer_list *timer)
914 struct loop_device *lo = container_of(timer, struct loop_device, timer);
916 return loop_free_idle_workers(lo, false);
919 static void loop_update_rotational(struct loop_device *lo)
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;
927 /* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
929 nonrot = bdev_nonrot(file_bdev);
932 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
934 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
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
942 * Configures the loop device parameters according to the passed
943 * in loop_info64 configuration.
946 loop_set_status_from_info(struct loop_device *lo,
947 const struct loop_info64 *info)
949 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
952 switch (info->lo_encrypt_type) {
956 pr_warn("support for the xor transformation has been removed.\n");
958 case LO_CRYPT_CRYPTOAPI:
959 pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
965 /* Avoid assigning overflow values */
966 if (info->lo_offset > LLONG_MAX || info->lo_sizelimit > LLONG_MAX)
969 lo->lo_offset = info->lo_offset;
970 lo->lo_sizelimit = info->lo_sizelimit;
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;
978 static int loop_reconfigure_limits(struct loop_device *lo, unsigned short bsize,
979 bool update_discard_settings)
981 struct queue_limits lim;
983 lim = queue_limits_start_update(lo->lo_queue);
984 lim.logical_block_size = bsize;
985 lim.physical_block_size = bsize;
987 if (update_discard_settings)
988 loop_config_discard(lo, &lim);
989 return queue_limits_commit_update(lo->lo_queue, &lim);
992 static int loop_configure(struct loop_device *lo, blk_mode_t mode,
993 struct block_device *bdev,
994 const struct loop_config *config)
996 struct file *file = fget(config->fd);
998 struct address_space *mapping;
1002 unsigned short bsize;
1007 is_loop = is_loop_device(file);
1009 /* This is safe, since we have a reference from open(). */
1010 __module_get(THIS_MODULE);
1013 * If we don't hold exclusive handle for the device, upgrade to it
1014 * here to avoid changing device under exclusive owner.
1016 if (!(mode & BLK_OPEN_EXCL)) {
1017 error = bd_prepare_to_claim(bdev, loop_configure, NULL);
1022 error = loop_global_lock_killable(lo, is_loop);
1027 if (lo->lo_state != Lo_unbound)
1030 error = loop_validate_file(file, bdev);
1034 mapping = file->f_mapping;
1035 inode = mapping->host;
1037 if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
1042 if (config->block_size) {
1043 error = blk_validate_block_size(config->block_size);
1048 error = loop_set_status_from_info(lo, &config->info);
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;
1056 if (!lo->workqueue) {
1057 lo->workqueue = alloc_workqueue("loop%d",
1058 WQ_UNBOUND | WQ_FREEZABLE,
1060 if (!lo->workqueue) {
1066 /* suppress uevents while reconfiguring the device */
1067 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
1069 disk_force_media_change(lo->lo_disk);
1070 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
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));
1078 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
1079 blk_queue_write_cache(lo->lo_queue, true, false);
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);
1089 error = loop_reconfigure_limits(lo, bsize, true);
1090 if (WARN_ON_ONCE(error))
1093 loop_update_rotational(lo);
1094 loop_update_dio(lo);
1095 loop_sysfs_init(lo);
1097 size = get_loop_size(lo, file);
1098 loop_set_size(lo, size);
1100 /* Order wrt reading lo_state in loop_validate_file(). */
1103 lo->lo_state = Lo_bound;
1105 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1106 partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
1108 clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
1110 /* enable and uncork uevent now that we are done */
1111 dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
1113 loop_global_unlock(lo, is_loop);
1115 loop_reread_partitions(lo);
1117 if (!(mode & BLK_OPEN_EXCL))
1118 bd_abort_claiming(bdev, loop_configure);
1123 loop_global_unlock(lo, is_loop);
1125 if (!(mode & BLK_OPEN_EXCL))
1126 bd_abort_claiming(bdev, loop_configure);
1129 /* This is safe: open() is still holding a reference. */
1130 module_put(THIS_MODULE);
1134 static void __loop_clr_fd(struct loop_device *lo, bool release)
1137 gfp_t gfp = lo->old_gfp_mask;
1139 if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
1140 blk_queue_write_cache(lo->lo_queue, false, false);
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.
1148 blk_mq_freeze_queue(lo->lo_queue);
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);
1155 lo->lo_device = NULL;
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);
1168 blk_mq_unfreeze_queue(lo->lo_queue);
1170 disk_force_media_change(lo->lo_disk);
1172 if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
1176 * open_mutex has been held already in release path, so don't
1177 * acquire it if this function is called in such case.
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.
1184 mutex_lock(&lo->lo_disk->open_mutex);
1185 err = bdev_disk_changed(lo->lo_disk, false);
1187 mutex_unlock(&lo->lo_disk->open_mutex);
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 */
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.
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);
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.
1215 static int loop_clr_fd(struct loop_device *lo)
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.
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
1228 err = loop_global_lock_killable(lo, true);
1231 if (lo->lo_state != Lo_bound) {
1232 loop_global_unlock(lo, true);
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.
1245 if (disk_openers(lo->lo_disk) > 1) {
1246 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1247 loop_global_unlock(lo, true);
1250 lo->lo_state = Lo_rundown;
1251 loop_global_unlock(lo, true);
1253 __loop_clr_fd(lo, false);
1258 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1262 bool partscan = false;
1263 bool size_changed = false;
1265 err = mutex_lock_killable(&lo->lo_mutex);
1268 if (lo->lo_state != Lo_bound) {
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);
1280 /* I/O need to be drained during transfer transition */
1281 blk_mq_freeze_queue(lo->lo_queue);
1283 prev_lo_flags = lo->lo_flags;
1285 err = loop_set_status_from_info(lo, info);
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;
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);
1302 /* update dio if lo_offset or transfer is changed */
1303 __loop_update_dio(lo, lo->use_dio);
1306 blk_mq_unfreeze_queue(lo->lo_queue);
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);
1314 mutex_unlock(&lo->lo_mutex);
1316 loop_reread_partitions(lo);
1322 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1328 ret = mutex_lock_killable(&lo->lo_mutex);
1331 if (lo->lo_state != Lo_bound) {
1332 mutex_unlock(&lo->lo_mutex);
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);
1343 /* Drop lo_mutex while we call into the filesystem. */
1344 path = lo->lo_backing_file->f_path;
1346 mutex_unlock(&lo->lo_mutex);
1347 ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
1349 info->lo_device = huge_encode_dev(stat.dev);
1350 info->lo_inode = stat.ino;
1351 info->lo_rdevice = huge_encode_dev(stat.rdev);
1358 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
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);
1372 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
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);
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)
1394 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1396 struct loop_info info;
1397 struct loop_info64 info64;
1399 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1401 loop_info64_from_old(&info, &info64);
1402 return loop_set_status(lo, &info64);
1406 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1408 struct loop_info64 info64;
1410 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1412 return loop_set_status(lo, &info64);
1416 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1417 struct loop_info info;
1418 struct loop_info64 info64;
1423 err = loop_get_status(lo, &info64);
1425 err = loop_info64_to_old(&info64, &info);
1426 if (!err && copy_to_user(arg, &info, sizeof(info)))
1433 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1434 struct loop_info64 info64;
1439 err = loop_get_status(lo, &info64);
1440 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1446 static int loop_set_capacity(struct loop_device *lo)
1450 if (unlikely(lo->lo_state != Lo_bound))
1453 size = get_loop_size(lo, lo->lo_backing_file);
1454 loop_set_size(lo, size);
1459 static int loop_set_dio(struct loop_device *lo, unsigned long arg)
1462 if (lo->lo_state != Lo_bound)
1465 __loop_update_dio(lo, !!arg);
1466 if (lo->use_dio == !!arg)
1473 static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
1477 if (lo->lo_state != Lo_bound)
1480 err = blk_validate_block_size(arg);
1484 if (lo->lo_queue->limits.logical_block_size == arg)
1487 sync_blockdev(lo->lo_device);
1488 invalidate_bdev(lo->lo_device);
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);
1498 static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
1503 err = mutex_lock_killable(&lo->lo_mutex);
1507 case LOOP_SET_CAPACITY:
1508 err = loop_set_capacity(lo);
1510 case LOOP_SET_DIRECT_IO:
1511 err = loop_set_dio(lo, arg);
1513 case LOOP_SET_BLOCK_SIZE:
1514 err = loop_set_block_size(lo, arg);
1519 mutex_unlock(&lo->lo_mutex);
1523 static int lo_ioctl(struct block_device *bdev, blk_mode_t mode,
1524 unsigned int cmd, unsigned long arg)
1526 struct loop_device *lo = bdev->bd_disk->private_data;
1527 void __user *argp = (void __user *) arg;
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.
1537 struct loop_config config;
1539 memset(&config, 0, sizeof(config));
1542 return loop_configure(lo, mode, bdev, &config);
1544 case LOOP_CONFIGURE: {
1545 struct loop_config config;
1547 if (copy_from_user(&config, argp, sizeof(config)))
1550 return loop_configure(lo, mode, bdev, &config);
1552 case LOOP_CHANGE_FD:
1553 return loop_change_fd(lo, bdev, arg);
1555 return loop_clr_fd(lo);
1556 case LOOP_SET_STATUS:
1558 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1559 err = loop_set_status_old(lo, argp);
1561 case LOOP_GET_STATUS:
1562 return loop_get_status_old(lo, argp);
1563 case LOOP_SET_STATUS64:
1565 if ((mode & BLK_OPEN_WRITE) || capable(CAP_SYS_ADMIN))
1566 err = loop_set_status64(lo, argp);
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))
1577 err = lo_simple_ioctl(lo, cmd, arg);
1584 #ifdef CONFIG_COMPAT
1585 struct 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];
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
1605 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1606 struct loop_info64 *info64)
1608 struct compat_loop_info info;
1610 if (copy_from_user(&info, arg, sizeof(info)))
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);
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
1630 loop_info64_to_compat(const struct loop_info64 *info64,
1631 struct compat_loop_info __user *arg)
1633 struct compat_loop_info info;
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);
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)
1651 if (copy_to_user(arg, &info, sizeof(info)))
1657 loop_set_status_compat(struct loop_device *lo,
1658 const struct compat_loop_info __user *arg)
1660 struct loop_info64 info64;
1663 ret = loop_info64_from_compat(arg, &info64);
1666 return loop_set_status(lo, &info64);
1670 loop_get_status_compat(struct loop_device *lo,
1671 struct compat_loop_info __user *arg)
1673 struct loop_info64 info64;
1678 err = loop_get_status(lo, &info64);
1680 err = loop_info64_to_compat(&info64, arg);
1684 static int lo_compat_ioctl(struct block_device *bdev, blk_mode_t mode,
1685 unsigned int cmd, unsigned long arg)
1687 struct loop_device *lo = bdev->bd_disk->private_data;
1691 case LOOP_SET_STATUS:
1692 err = loop_set_status_compat(lo,
1693 (const struct compat_loop_info __user *)arg);
1695 case LOOP_GET_STATUS:
1696 err = loop_get_status_compat(lo,
1697 (struct compat_loop_info __user *)arg);
1699 case LOOP_SET_CAPACITY:
1701 case LOOP_GET_STATUS64:
1702 case LOOP_SET_STATUS64:
1703 case LOOP_CONFIGURE:
1704 arg = (unsigned long) compat_ptr(arg);
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);
1720 static void lo_release(struct gendisk *disk)
1722 struct loop_device *lo = disk->private_data;
1724 if (disk_openers(disk) > 0)
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);
1732 * In autoclear mode, stop the loop thread
1733 * and remove configuration after last close.
1735 __loop_clr_fd(lo, true);
1738 mutex_unlock(&lo->lo_mutex);
1741 static void lo_free_disk(struct gendisk *disk)
1743 struct loop_device *lo = disk->private_data;
1746 destroy_workqueue(lo->workqueue);
1747 loop_free_idle_workers(lo, true);
1748 timer_shutdown_sync(&lo->timer);
1749 mutex_destroy(&lo->lo_mutex);
1753 static const struct block_device_operations lo_fops = {
1754 .owner = THIS_MODULE,
1755 .release = lo_release,
1757 #ifdef CONFIG_COMPAT
1758 .compat_ioctl = lo_compat_ioctl,
1760 .free_disk = lo_free_disk,
1764 * And now the modules code and kernel interface.
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.
1777 static int max_loop = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1779 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
1780 static bool max_loop_specified;
1782 static int max_loop_param_set_int(const char *val,
1783 const struct kernel_param *kp)
1787 ret = param_set_int(val, kp);
1791 max_loop_specified = true;
1795 static const struct kernel_param_ops max_loop_param_ops = {
1796 .set = max_loop_param_set_int,
1797 .get = param_get_int,
1800 module_param_cb(max_loop, &max_loop_param_ops, &max_loop, 0444);
1801 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1803 module_param(max_loop, int, 0444);
1804 MODULE_PARM_DESC(max_loop, "Initial number of loop devices");
1807 module_param(max_part, int, 0444);
1808 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1810 static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
1812 static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
1816 ret = kstrtoint(s, 0, &qd);
1821 hw_queue_depth = qd;
1825 static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
1826 .set = loop_set_hw_queue_depth,
1827 .get = param_get_int,
1830 device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
1831 MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: " __stringify(LOOP_DEFAULT_HW_Q_DEPTH));
1833 MODULE_LICENSE("GPL");
1834 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1836 static blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1837 const struct blk_mq_queue_data *bd)
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;
1843 blk_mq_start_request(rq);
1845 if (lo->lo_state != Lo_bound)
1846 return BLK_STS_IOERR;
1848 switch (req_op(rq)) {
1850 case REQ_OP_DISCARD:
1851 case REQ_OP_WRITE_ZEROES:
1852 cmd->use_aio = false;
1855 cmd->use_aio = lo->use_dio;
1859 /* always use the first bio's css */
1860 cmd->blkcg_css = NULL;
1861 cmd->memcg_css = NULL;
1862 #ifdef CONFIG_BLK_CGROUP
1864 cmd->blkcg_css = bio_blkcg_css(rq->bio);
1866 if (cmd->blkcg_css) {
1868 cgroup_get_e_css(cmd->blkcg_css->cgroup,
1869 &memory_cgrp_subsys);
1874 loop_queue_work(lo, cmd);
1879 static void loop_handle_cmd(struct loop_cmd *cmd)
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;
1887 struct mem_cgroup *old_memcg = NULL;
1888 const bool use_aio = cmd->use_aio;
1890 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
1896 kthread_associate_blkcg(cmd_blkcg_css);
1898 old_memcg = set_active_memcg(
1899 mem_cgroup_from_css(cmd_memcg_css));
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.
1907 ret = do_req_filebacked(lo, rq);
1910 kthread_associate_blkcg(NULL);
1912 if (cmd_memcg_css) {
1913 set_active_memcg(old_memcg);
1914 css_put(cmd_memcg_css);
1917 /* complete non-aio request */
1918 if (!use_aio || ret) {
1919 if (ret == -EOPNOTSUPP)
1922 cmd->ret = ret ? -EIO : 0;
1923 if (likely(!blk_should_fake_timeout(rq->q)))
1924 blk_mq_complete_request(rq);
1928 static void loop_process_work(struct loop_worker *worker,
1929 struct list_head *cmd_list, struct loop_device *lo)
1931 int orig_flags = current->flags;
1932 struct loop_cmd *cmd;
1934 current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
1935 spin_lock_irq(&lo->lo_work_lock);
1936 while (!list_empty(cmd_list)) {
1938 cmd_list->next, struct loop_cmd, list_entry);
1939 list_del(cmd_list->next);
1940 spin_unlock_irq(&lo->lo_work_lock);
1942 loop_handle_cmd(cmd);
1945 spin_lock_irq(&lo->lo_work_lock);
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
1953 if (worker && !work_pending(&worker->work)) {
1954 worker->last_ran_at = jiffies;
1955 list_add_tail(&worker->idle_list, &lo->idle_worker_list);
1958 spin_unlock_irq(&lo->lo_work_lock);
1959 current->flags = orig_flags;
1962 static void loop_workfn(struct work_struct *work)
1964 struct loop_worker *worker =
1965 container_of(work, struct loop_worker, work);
1966 loop_process_work(worker, &worker->cmd_list, worker->lo);
1969 static void loop_rootcg_workfn(struct work_struct *work)
1971 struct loop_device *lo =
1972 container_of(work, struct loop_device, rootcg_work);
1973 loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
1976 static const struct blk_mq_ops loop_mq_ops = {
1977 .queue_rq = loop_queue_rq,
1978 .complete = lo_complete_rq,
1981 static int loop_add(int i)
1983 struct queue_limits lim = {
1985 * Random number picked from the historic block max_sectors cap.
1987 .max_hw_sectors = 2560u,
1989 struct loop_device *lo;
1990 struct gendisk *disk;
1994 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
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;
2002 err = mutex_lock_killable(&loop_ctl_mutex);
2006 /* allocate id, if @id >= 0, we're requesting that specific id */
2008 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
2012 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
2014 mutex_unlock(&loop_ctl_mutex);
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;
2028 err = blk_mq_alloc_tag_set(&lo->tag_set);
2032 disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, &lim, lo);
2034 err = PTR_ERR(disk);
2035 goto out_cleanup_tags;
2037 lo->lo_queue = lo->lo_disk->queue;
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.
2045 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
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
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.
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.
2066 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2067 mutex_init(&lo->lo_mutex);
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);
2085 goto out_cleanup_disk;
2087 /* Show this loop device. */
2088 mutex_lock(&loop_ctl_mutex);
2089 lo->idr_visible = true;
2090 mutex_unlock(&loop_ctl_mutex);
2097 blk_mq_free_tag_set(&lo->tag_set);
2099 mutex_lock(&loop_ctl_mutex);
2100 idr_remove(&loop_index_idr, i);
2101 mutex_unlock(&loop_ctl_mutex);
2108 static void loop_remove(struct loop_device *lo)
2110 /* Make this loop device unreachable from pathname. */
2111 del_gendisk(lo->lo_disk);
2112 blk_mq_free_tag_set(&lo->tag_set);
2114 mutex_lock(&loop_ctl_mutex);
2115 idr_remove(&loop_index_idr, lo->lo_number);
2116 mutex_unlock(&loop_ctl_mutex);
2118 put_disk(lo->lo_disk);
2121 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2122 static void loop_probe(dev_t dev)
2124 int idx = MINOR(dev) >> part_shift;
2126 if (max_loop_specified && max_loop && idx >= max_loop)
2131 #define loop_probe NULL
2132 #endif /* !CONFIG_BLOCK_LEGACY_AUTOLOAD */
2134 static int loop_control_remove(int idx)
2136 struct loop_device *lo;
2140 pr_warn_once("deleting an unspecified loop device is not supported.\n");
2144 /* Hide this loop device for serialization. */
2145 ret = mutex_lock_killable(&loop_ctl_mutex);
2148 lo = idr_find(&loop_index_idr, idx);
2149 if (!lo || !lo->idr_visible)
2152 lo->idr_visible = false;
2153 mutex_unlock(&loop_ctl_mutex);
2157 /* Check whether this loop device can be removed. */
2158 ret = mutex_lock_killable(&lo->lo_mutex);
2161 if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
2162 mutex_unlock(&lo->lo_mutex);
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);
2174 /* Show this loop device again. */
2175 mutex_lock(&loop_ctl_mutex);
2176 lo->idr_visible = true;
2177 mutex_unlock(&loop_ctl_mutex);
2181 static int loop_control_get_free(int idx)
2183 struct loop_device *lo;
2186 ret = mutex_lock_killable(&loop_ctl_mutex);
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)
2194 mutex_unlock(&loop_ctl_mutex);
2195 return loop_add(-1);
2197 mutex_unlock(&loop_ctl_mutex);
2201 static long loop_control_ioctl(struct file *file, unsigned int cmd,
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);
2216 static 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,
2224 static struct miscdevice loop_misc = {
2225 .minor = LOOP_CTRL_MINOR,
2226 .name = "loop-control",
2227 .fops = &loop_ctl_fops,
2230 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
2231 MODULE_ALIAS("devname:loop-control");
2233 static int __init loop_init(void)
2240 part_shift = fls(max_part);
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.
2247 * Note that -1 is required because partition 0 is reserved
2248 * for the whole disk.
2250 max_part = (1UL << part_shift) - 1;
2253 if ((1UL << part_shift) > DISK_MAX_PARTS) {
2258 if (max_loop > 1UL << (MINORBITS - part_shift)) {
2263 err = misc_register(&loop_misc);
2268 if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
2273 /* pre-create number of devices given by config or max_loop */
2274 for (i = 0; i < max_loop; i++)
2277 printk(KERN_INFO "loop: module loaded\n");
2281 misc_deregister(&loop_misc);
2286 static void __exit loop_exit(void)
2288 struct loop_device *lo;
2291 unregister_blkdev(LOOP_MAJOR, "loop");
2292 misc_deregister(&loop_misc);
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.
2300 idr_for_each_entry(&loop_index_idr, lo, id)
2303 idr_destroy(&loop_index_idr);
2306 module_init(loop_init);
2307 module_exit(loop_exit);
2310 static int __init max_loop_setup(char *str)
2312 max_loop = simple_strtol(str, NULL, 0);
2313 #ifdef CONFIG_BLOCK_LEGACY_AUTOLOAD
2314 max_loop_specified = true;
2319 __setup("max_loop=", max_loop_setup);