2 * linux/drivers/block/loop.c
4 * Written by Theodore Ts'o, 3/29/93
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
21 * Loadable modules and other fixes by AK, 1998
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
37 * Jens Axboe <axboe@suse.de>, Nov 2000
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
52 #include <linux/module.h>
53 #include <linux/moduleparam.h>
54 #include <linux/sched.h>
56 #include <linux/file.h>
57 #include <linux/stat.h>
58 #include <linux/errno.h>
59 #include <linux/major.h>
60 #include <linux/wait.h>
61 #include <linux/blkdev.h>
62 #include <linux/blkpg.h>
63 #include <linux/init.h>
64 #include <linux/swap.h>
65 #include <linux/slab.h>
66 #include <linux/compat.h>
67 #include <linux/suspend.h>
68 #include <linux/freezer.h>
69 #include <linux/mutex.h>
70 #include <linux/writeback.h>
71 #include <linux/completion.h>
72 #include <linux/highmem.h>
73 #include <linux/kthread.h>
74 #include <linux/splice.h>
75 #include <linux/sysfs.h>
76 #include <linux/miscdevice.h>
77 #include <linux/falloc.h>
78 #include <linux/uio.h>
81 #include <asm/uaccess.h>
83 static DEFINE_IDR(loop_index_idr);
84 static DEFINE_MUTEX(loop_index_mutex);
87 static int part_shift;
89 static int transfer_xor(struct loop_device *lo, int cmd,
90 struct page *raw_page, unsigned raw_off,
91 struct page *loop_page, unsigned loop_off,
92 int size, sector_t real_block)
94 char *raw_buf = kmap_atomic(raw_page) + raw_off;
95 char *loop_buf = kmap_atomic(loop_page) + loop_off;
107 key = lo->lo_encrypt_key;
108 keysize = lo->lo_encrypt_key_size;
109 for (i = 0; i < size; i++)
110 *out++ = *in++ ^ key[(i & 511) % keysize];
112 kunmap_atomic(loop_buf);
113 kunmap_atomic(raw_buf);
118 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
120 if (unlikely(info->lo_encrypt_key_size <= 0))
125 static struct loop_func_table none_funcs = {
126 .number = LO_CRYPT_NONE,
129 static struct loop_func_table xor_funcs = {
130 .number = LO_CRYPT_XOR,
131 .transfer = transfer_xor,
135 /* xfer_funcs[0] is special - its release function is never called */
136 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
141 static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
145 /* Compute loopsize in bytes */
146 loopsize = i_size_read(file->f_mapping->host);
149 /* offset is beyond i_size, weird but possible */
153 if (sizelimit > 0 && sizelimit < loopsize)
154 loopsize = sizelimit;
156 * Unfortunately, if we want to do I/O on the device,
157 * the number of 512-byte sectors has to fit into a sector_t.
159 return loopsize >> 9;
162 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
164 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
168 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
170 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
171 sector_t x = (sector_t)size;
172 struct block_device *bdev = lo->lo_device;
174 if (unlikely((loff_t)x != size))
176 if (lo->lo_offset != offset)
177 lo->lo_offset = offset;
178 if (lo->lo_sizelimit != sizelimit)
179 lo->lo_sizelimit = sizelimit;
180 set_capacity(lo->lo_disk, x);
181 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
182 /* let user-space know about the new size */
183 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
188 lo_do_transfer(struct loop_device *lo, int cmd,
189 struct page *rpage, unsigned roffs,
190 struct page *lpage, unsigned loffs,
191 int size, sector_t rblock)
195 ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
199 printk_ratelimited(KERN_ERR
200 "loop: Transfer error at byte offset %llu, length %i.\n",
201 (unsigned long long)rblock << 9, size);
205 static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
210 iov_iter_bvec(&i, ITER_BVEC, bvec, 1, bvec->bv_len);
212 file_start_write(file);
213 bw = vfs_iter_write(file, &i, ppos);
214 file_end_write(file);
216 if (likely(bw == bvec->bv_len))
219 printk_ratelimited(KERN_ERR
220 "loop: Write error at byte offset %llu, length %i.\n",
221 (unsigned long long)*ppos, bvec->bv_len);
227 static int lo_write_simple(struct loop_device *lo, struct request *rq,
231 struct req_iterator iter;
234 rq_for_each_segment(bvec, rq, iter) {
235 ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
245 * This is the slow, transforming version that needs to double buffer the
246 * data as it cannot do the transformations in place without having direct
247 * access to the destination pages of the backing file.
249 static int lo_write_transfer(struct loop_device *lo, struct request *rq,
252 struct bio_vec bvec, b;
253 struct req_iterator iter;
257 page = alloc_page(GFP_NOIO);
261 rq_for_each_segment(bvec, rq, iter) {
262 ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
263 bvec.bv_offset, bvec.bv_len, pos >> 9);
269 b.bv_len = bvec.bv_len;
270 ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
279 static int lo_read_simple(struct loop_device *lo, struct request *rq,
283 struct req_iterator iter;
287 rq_for_each_segment(bvec, rq, iter) {
288 iov_iter_bvec(&i, ITER_BVEC, &bvec, 1, bvec.bv_len);
289 len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
293 flush_dcache_page(bvec.bv_page);
295 if (len != bvec.bv_len) {
298 __rq_for_each_bio(bio, rq)
308 static int lo_read_transfer(struct loop_device *lo, struct request *rq,
311 struct bio_vec bvec, b;
312 struct req_iterator iter;
318 page = alloc_page(GFP_NOIO);
322 rq_for_each_segment(bvec, rq, iter) {
327 b.bv_len = bvec.bv_len;
329 iov_iter_bvec(&i, ITER_BVEC, &b, 1, b.bv_len);
330 len = vfs_iter_read(lo->lo_backing_file, &i, &pos);
336 ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
337 bvec.bv_offset, len, offset >> 9);
341 flush_dcache_page(bvec.bv_page);
343 if (len != bvec.bv_len) {
346 __rq_for_each_bio(bio, rq)
358 static int lo_discard(struct loop_device *lo, struct request *rq, loff_t pos)
361 * We use punch hole to reclaim the free space used by the
362 * image a.k.a. discard. However we do not support discard if
363 * encryption is enabled, because it may give an attacker
364 * useful information.
366 struct file *file = lo->lo_backing_file;
367 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
370 if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size) {
375 ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
376 if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
382 static int lo_req_flush(struct loop_device *lo, struct request *rq)
384 struct file *file = lo->lo_backing_file;
385 int ret = vfs_fsync(file, 0);
386 if (unlikely(ret && ret != -EINVAL))
392 static int do_req_filebacked(struct loop_device *lo, struct request *rq)
397 pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
399 if (rq->cmd_flags & REQ_WRITE) {
400 if (rq->cmd_flags & REQ_FLUSH)
401 ret = lo_req_flush(lo, rq);
402 else if (rq->cmd_flags & REQ_DISCARD)
403 ret = lo_discard(lo, rq, pos);
404 else if (lo->transfer)
405 ret = lo_write_transfer(lo, rq, pos);
407 ret = lo_write_simple(lo, rq, pos);
411 ret = lo_read_transfer(lo, rq, pos);
413 ret = lo_read_simple(lo, rq, pos);
419 struct switch_request {
421 struct completion wait;
425 * Do the actual switch; called from the BIO completion routine
427 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
429 struct file *file = p->file;
430 struct file *old_file = lo->lo_backing_file;
431 struct address_space *mapping;
433 /* if no new file, only flush of queued bios requested */
437 mapping = file->f_mapping;
438 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
439 lo->lo_backing_file = file;
440 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
441 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
442 lo->old_gfp_mask = mapping_gfp_mask(mapping);
443 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
447 * loop_switch performs the hard work of switching a backing store.
448 * First it needs to flush existing IO, it does this by sending a magic
449 * BIO down the pipe. The completion of this BIO does the actual switch.
451 static int loop_switch(struct loop_device *lo, struct file *file)
453 struct switch_request w;
457 /* freeze queue and wait for completion of scheduled requests */
458 blk_mq_freeze_queue(lo->lo_queue);
460 /* do the switch action */
461 do_loop_switch(lo, &w);
464 blk_mq_unfreeze_queue(lo->lo_queue);
470 * Helper to flush the IOs in loop, but keeping loop thread running
472 static int loop_flush(struct loop_device *lo)
474 return loop_switch(lo, NULL);
478 * loop_change_fd switched the backing store of a loopback device to
479 * a new file. This is useful for operating system installers to free up
480 * the original file and in High Availability environments to switch to
481 * an alternative location for the content in case of server meltdown.
482 * This can only work if the loop device is used read-only, and if the
483 * new backing store is the same size and type as the old backing store.
485 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
488 struct file *file, *old_file;
493 if (lo->lo_state != Lo_bound)
496 /* the loop device has to be read-only */
498 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
506 inode = file->f_mapping->host;
507 old_file = lo->lo_backing_file;
511 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
514 /* size of the new backing store needs to be the same */
515 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
519 error = loop_switch(lo, file);
524 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
525 ioctl_by_bdev(bdev, BLKRRPART, 0);
534 static inline int is_loop_device(struct file *file)
536 struct inode *i = file->f_mapping->host;
538 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
541 /* loop sysfs attributes */
543 static ssize_t loop_attr_show(struct device *dev, char *page,
544 ssize_t (*callback)(struct loop_device *, char *))
546 struct gendisk *disk = dev_to_disk(dev);
547 struct loop_device *lo = disk->private_data;
549 return callback(lo, page);
552 #define LOOP_ATTR_RO(_name) \
553 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
554 static ssize_t loop_attr_do_show_##_name(struct device *d, \
555 struct device_attribute *attr, char *b) \
557 return loop_attr_show(d, b, loop_attr_##_name##_show); \
559 static struct device_attribute loop_attr_##_name = \
560 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
562 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
567 spin_lock_irq(&lo->lo_lock);
568 if (lo->lo_backing_file)
569 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
570 spin_unlock_irq(&lo->lo_lock);
572 if (IS_ERR_OR_NULL(p))
576 memmove(buf, p, ret);
584 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
586 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
589 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
591 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
594 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
596 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
598 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
601 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
603 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
605 return sprintf(buf, "%s\n", partscan ? "1" : "0");
608 LOOP_ATTR_RO(backing_file);
609 LOOP_ATTR_RO(offset);
610 LOOP_ATTR_RO(sizelimit);
611 LOOP_ATTR_RO(autoclear);
612 LOOP_ATTR_RO(partscan);
614 static struct attribute *loop_attrs[] = {
615 &loop_attr_backing_file.attr,
616 &loop_attr_offset.attr,
617 &loop_attr_sizelimit.attr,
618 &loop_attr_autoclear.attr,
619 &loop_attr_partscan.attr,
623 static struct attribute_group loop_attribute_group = {
628 static int loop_sysfs_init(struct loop_device *lo)
630 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
631 &loop_attribute_group);
634 static void loop_sysfs_exit(struct loop_device *lo)
636 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
637 &loop_attribute_group);
640 static void loop_config_discard(struct loop_device *lo)
642 struct file *file = lo->lo_backing_file;
643 struct inode *inode = file->f_mapping->host;
644 struct request_queue *q = lo->lo_queue;
647 * We use punch hole to reclaim the free space used by the
648 * image a.k.a. discard. However we do not support discard if
649 * encryption is enabled, because it may give an attacker
650 * useful information.
652 if ((!file->f_op->fallocate) ||
653 lo->lo_encrypt_key_size) {
654 q->limits.discard_granularity = 0;
655 q->limits.discard_alignment = 0;
656 q->limits.max_discard_sectors = 0;
657 q->limits.discard_zeroes_data = 0;
658 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
662 q->limits.discard_granularity = inode->i_sb->s_blocksize;
663 q->limits.discard_alignment = 0;
664 q->limits.max_discard_sectors = UINT_MAX >> 9;
665 q->limits.discard_zeroes_data = 1;
666 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
669 static int loop_set_fd(struct loop_device *lo, fmode_t mode,
670 struct block_device *bdev, unsigned int arg)
672 struct file *file, *f;
674 struct address_space *mapping;
675 unsigned lo_blocksize;
680 /* This is safe, since we have a reference from open(). */
681 __module_get(THIS_MODULE);
689 if (lo->lo_state != Lo_unbound)
692 /* Avoid recursion */
694 while (is_loop_device(f)) {
695 struct loop_device *l;
697 if (f->f_mapping->host->i_bdev == bdev)
700 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
701 if (l->lo_state == Lo_unbound) {
705 f = l->lo_backing_file;
708 mapping = file->f_mapping;
709 inode = mapping->host;
712 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
715 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
716 !file->f_op->write_iter)
717 lo_flags |= LO_FLAGS_READ_ONLY;
719 lo_blocksize = S_ISBLK(inode->i_mode) ?
720 inode->i_bdev->bd_block_size : PAGE_SIZE;
723 size = get_loop_size(lo, file);
724 if ((loff_t)(sector_t)size != size)
727 lo->wq = alloc_workqueue("kloopd%d",
728 WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 16,
735 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
737 lo->lo_blocksize = lo_blocksize;
738 lo->lo_device = bdev;
739 lo->lo_flags = lo_flags;
740 lo->lo_backing_file = file;
743 lo->lo_sizelimit = 0;
744 lo->old_gfp_mask = mapping_gfp_mask(mapping);
745 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
747 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
748 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
750 set_capacity(lo->lo_disk, size);
751 bd_set_size(bdev, size << 9);
753 /* let user-space know about the new size */
754 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
756 set_blocksize(bdev, lo_blocksize);
758 lo->lo_state = Lo_bound;
760 lo->lo_flags |= LO_FLAGS_PARTSCAN;
761 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
762 ioctl_by_bdev(bdev, BLKRRPART, 0);
764 /* Grab the block_device to prevent its destruction after we
765 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
773 /* This is safe: open() is still holding a reference. */
774 module_put(THIS_MODULE);
779 loop_release_xfer(struct loop_device *lo)
782 struct loop_func_table *xfer = lo->lo_encryption;
786 err = xfer->release(lo);
788 lo->lo_encryption = NULL;
789 module_put(xfer->owner);
795 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
796 const struct loop_info64 *i)
801 struct module *owner = xfer->owner;
803 if (!try_module_get(owner))
806 err = xfer->init(lo, i);
810 lo->lo_encryption = xfer;
815 static int loop_clr_fd(struct loop_device *lo)
817 struct file *filp = lo->lo_backing_file;
818 gfp_t gfp = lo->old_gfp_mask;
819 struct block_device *bdev = lo->lo_device;
821 if (lo->lo_state != Lo_bound)
825 * If we've explicitly asked to tear down the loop device,
826 * and it has an elevated reference count, set it for auto-teardown when
827 * the last reference goes away. This stops $!~#$@ udev from
828 * preventing teardown because it decided that it needs to run blkid on
829 * the loopback device whenever they appear. xfstests is notorious for
830 * failing tests because blkid via udev races with a losetup
831 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
832 * command to fail with EBUSY.
834 if (lo->lo_refcnt > 1) {
835 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
836 mutex_unlock(&lo->lo_ctl_mutex);
843 spin_lock_irq(&lo->lo_lock);
844 lo->lo_state = Lo_rundown;
845 lo->lo_backing_file = NULL;
846 spin_unlock_irq(&lo->lo_lock);
848 loop_release_xfer(lo);
851 lo->lo_device = NULL;
852 lo->lo_encryption = NULL;
854 lo->lo_sizelimit = 0;
855 lo->lo_encrypt_key_size = 0;
856 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
857 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
858 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
861 invalidate_bdev(bdev);
863 set_capacity(lo->lo_disk, 0);
866 bd_set_size(bdev, 0);
867 /* let user-space know about this change */
868 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
870 mapping_set_gfp_mask(filp->f_mapping, gfp);
871 lo->lo_state = Lo_unbound;
872 /* This is safe: open() is still holding a reference. */
873 module_put(THIS_MODULE);
874 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
875 ioctl_by_bdev(bdev, BLKRRPART, 0);
878 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
879 destroy_workqueue(lo->wq);
881 mutex_unlock(&lo->lo_ctl_mutex);
883 * Need not hold lo_ctl_mutex to fput backing file.
884 * Calling fput holding lo_ctl_mutex triggers a circular
885 * lock dependency possibility warning as fput can take
886 * bd_mutex which is usually taken before lo_ctl_mutex.
893 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
896 struct loop_func_table *xfer;
897 kuid_t uid = current_uid();
899 if (lo->lo_encrypt_key_size &&
900 !uid_eq(lo->lo_key_owner, uid) &&
901 !capable(CAP_SYS_ADMIN))
903 if (lo->lo_state != Lo_bound)
905 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
908 err = loop_release_xfer(lo);
912 if (info->lo_encrypt_type) {
913 unsigned int type = info->lo_encrypt_type;
915 if (type >= MAX_LO_CRYPT)
917 xfer = xfer_funcs[type];
923 err = loop_init_xfer(lo, xfer, info);
927 if (lo->lo_offset != info->lo_offset ||
928 lo->lo_sizelimit != info->lo_sizelimit)
929 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
932 loop_config_discard(lo);
934 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
935 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
936 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
937 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
941 lo->transfer = xfer->transfer;
942 lo->ioctl = xfer->ioctl;
944 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
945 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
946 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
948 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
949 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
950 lo->lo_flags |= LO_FLAGS_PARTSCAN;
951 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
952 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
955 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
956 lo->lo_init[0] = info->lo_init[0];
957 lo->lo_init[1] = info->lo_init[1];
958 if (info->lo_encrypt_key_size) {
959 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
960 info->lo_encrypt_key_size);
961 lo->lo_key_owner = uid;
968 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
970 struct file *file = lo->lo_backing_file;
974 if (lo->lo_state != Lo_bound)
976 error = vfs_getattr(&file->f_path, &stat);
979 memset(info, 0, sizeof(*info));
980 info->lo_number = lo->lo_number;
981 info->lo_device = huge_encode_dev(stat.dev);
982 info->lo_inode = stat.ino;
983 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
984 info->lo_offset = lo->lo_offset;
985 info->lo_sizelimit = lo->lo_sizelimit;
986 info->lo_flags = lo->lo_flags;
987 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
988 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
989 info->lo_encrypt_type =
990 lo->lo_encryption ? lo->lo_encryption->number : 0;
991 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
992 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
993 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
994 lo->lo_encrypt_key_size);
1000 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1002 memset(info64, 0, sizeof(*info64));
1003 info64->lo_number = info->lo_number;
1004 info64->lo_device = info->lo_device;
1005 info64->lo_inode = info->lo_inode;
1006 info64->lo_rdevice = info->lo_rdevice;
1007 info64->lo_offset = info->lo_offset;
1008 info64->lo_sizelimit = 0;
1009 info64->lo_encrypt_type = info->lo_encrypt_type;
1010 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1011 info64->lo_flags = info->lo_flags;
1012 info64->lo_init[0] = info->lo_init[0];
1013 info64->lo_init[1] = info->lo_init[1];
1014 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1015 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1017 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1018 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1022 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1024 memset(info, 0, sizeof(*info));
1025 info->lo_number = info64->lo_number;
1026 info->lo_device = info64->lo_device;
1027 info->lo_inode = info64->lo_inode;
1028 info->lo_rdevice = info64->lo_rdevice;
1029 info->lo_offset = info64->lo_offset;
1030 info->lo_encrypt_type = info64->lo_encrypt_type;
1031 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1032 info->lo_flags = info64->lo_flags;
1033 info->lo_init[0] = info64->lo_init[0];
1034 info->lo_init[1] = info64->lo_init[1];
1035 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1036 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1038 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1039 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1041 /* error in case values were truncated */
1042 if (info->lo_device != info64->lo_device ||
1043 info->lo_rdevice != info64->lo_rdevice ||
1044 info->lo_inode != info64->lo_inode ||
1045 info->lo_offset != info64->lo_offset)
1052 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1054 struct loop_info info;
1055 struct loop_info64 info64;
1057 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1059 loop_info64_from_old(&info, &info64);
1060 return loop_set_status(lo, &info64);
1064 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1066 struct loop_info64 info64;
1068 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1070 return loop_set_status(lo, &info64);
1074 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1075 struct loop_info info;
1076 struct loop_info64 info64;
1082 err = loop_get_status(lo, &info64);
1084 err = loop_info64_to_old(&info64, &info);
1085 if (!err && copy_to_user(arg, &info, sizeof(info)))
1092 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1093 struct loop_info64 info64;
1099 err = loop_get_status(lo, &info64);
1100 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1106 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1108 if (unlikely(lo->lo_state != Lo_bound))
1111 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1114 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1115 unsigned int cmd, unsigned long arg)
1117 struct loop_device *lo = bdev->bd_disk->private_data;
1120 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1123 err = loop_set_fd(lo, mode, bdev, arg);
1125 case LOOP_CHANGE_FD:
1126 err = loop_change_fd(lo, bdev, arg);
1129 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1130 err = loop_clr_fd(lo);
1134 case LOOP_SET_STATUS:
1136 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1137 err = loop_set_status_old(lo,
1138 (struct loop_info __user *)arg);
1140 case LOOP_GET_STATUS:
1141 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1143 case LOOP_SET_STATUS64:
1145 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1146 err = loop_set_status64(lo,
1147 (struct loop_info64 __user *) arg);
1149 case LOOP_GET_STATUS64:
1150 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1152 case LOOP_SET_CAPACITY:
1154 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1155 err = loop_set_capacity(lo, bdev);
1158 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1160 mutex_unlock(&lo->lo_ctl_mutex);
1166 #ifdef CONFIG_COMPAT
1167 struct compat_loop_info {
1168 compat_int_t lo_number; /* ioctl r/o */
1169 compat_dev_t lo_device; /* ioctl r/o */
1170 compat_ulong_t lo_inode; /* ioctl r/o */
1171 compat_dev_t lo_rdevice; /* ioctl r/o */
1172 compat_int_t lo_offset;
1173 compat_int_t lo_encrypt_type;
1174 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1175 compat_int_t lo_flags; /* ioctl r/o */
1176 char lo_name[LO_NAME_SIZE];
1177 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1178 compat_ulong_t lo_init[2];
1183 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1184 * - noinlined to reduce stack space usage in main part of driver
1187 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1188 struct loop_info64 *info64)
1190 struct compat_loop_info info;
1192 if (copy_from_user(&info, arg, sizeof(info)))
1195 memset(info64, 0, sizeof(*info64));
1196 info64->lo_number = info.lo_number;
1197 info64->lo_device = info.lo_device;
1198 info64->lo_inode = info.lo_inode;
1199 info64->lo_rdevice = info.lo_rdevice;
1200 info64->lo_offset = info.lo_offset;
1201 info64->lo_sizelimit = 0;
1202 info64->lo_encrypt_type = info.lo_encrypt_type;
1203 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1204 info64->lo_flags = info.lo_flags;
1205 info64->lo_init[0] = info.lo_init[0];
1206 info64->lo_init[1] = info.lo_init[1];
1207 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1208 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1210 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1211 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1216 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1217 * - noinlined to reduce stack space usage in main part of driver
1220 loop_info64_to_compat(const struct loop_info64 *info64,
1221 struct compat_loop_info __user *arg)
1223 struct compat_loop_info info;
1225 memset(&info, 0, sizeof(info));
1226 info.lo_number = info64->lo_number;
1227 info.lo_device = info64->lo_device;
1228 info.lo_inode = info64->lo_inode;
1229 info.lo_rdevice = info64->lo_rdevice;
1230 info.lo_offset = info64->lo_offset;
1231 info.lo_encrypt_type = info64->lo_encrypt_type;
1232 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1233 info.lo_flags = info64->lo_flags;
1234 info.lo_init[0] = info64->lo_init[0];
1235 info.lo_init[1] = info64->lo_init[1];
1236 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1237 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1239 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1240 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1242 /* error in case values were truncated */
1243 if (info.lo_device != info64->lo_device ||
1244 info.lo_rdevice != info64->lo_rdevice ||
1245 info.lo_inode != info64->lo_inode ||
1246 info.lo_offset != info64->lo_offset ||
1247 info.lo_init[0] != info64->lo_init[0] ||
1248 info.lo_init[1] != info64->lo_init[1])
1251 if (copy_to_user(arg, &info, sizeof(info)))
1257 loop_set_status_compat(struct loop_device *lo,
1258 const struct compat_loop_info __user *arg)
1260 struct loop_info64 info64;
1263 ret = loop_info64_from_compat(arg, &info64);
1266 return loop_set_status(lo, &info64);
1270 loop_get_status_compat(struct loop_device *lo,
1271 struct compat_loop_info __user *arg)
1273 struct loop_info64 info64;
1279 err = loop_get_status(lo, &info64);
1281 err = loop_info64_to_compat(&info64, arg);
1285 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1286 unsigned int cmd, unsigned long arg)
1288 struct loop_device *lo = bdev->bd_disk->private_data;
1292 case LOOP_SET_STATUS:
1293 mutex_lock(&lo->lo_ctl_mutex);
1294 err = loop_set_status_compat(
1295 lo, (const struct compat_loop_info __user *) arg);
1296 mutex_unlock(&lo->lo_ctl_mutex);
1298 case LOOP_GET_STATUS:
1299 mutex_lock(&lo->lo_ctl_mutex);
1300 err = loop_get_status_compat(
1301 lo, (struct compat_loop_info __user *) arg);
1302 mutex_unlock(&lo->lo_ctl_mutex);
1304 case LOOP_SET_CAPACITY:
1306 case LOOP_GET_STATUS64:
1307 case LOOP_SET_STATUS64:
1308 arg = (unsigned long) compat_ptr(arg);
1310 case LOOP_CHANGE_FD:
1311 err = lo_ioctl(bdev, mode, cmd, arg);
1321 static int lo_open(struct block_device *bdev, fmode_t mode)
1323 struct loop_device *lo;
1326 mutex_lock(&loop_index_mutex);
1327 lo = bdev->bd_disk->private_data;
1333 mutex_lock(&lo->lo_ctl_mutex);
1335 mutex_unlock(&lo->lo_ctl_mutex);
1337 mutex_unlock(&loop_index_mutex);
1341 static void lo_release(struct gendisk *disk, fmode_t mode)
1343 struct loop_device *lo = disk->private_data;
1346 mutex_lock(&lo->lo_ctl_mutex);
1348 if (--lo->lo_refcnt)
1351 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1353 * In autoclear mode, stop the loop thread
1354 * and remove configuration after last close.
1356 err = loop_clr_fd(lo);
1361 * Otherwise keep thread (if running) and config,
1362 * but flush possible ongoing bios in thread.
1368 mutex_unlock(&lo->lo_ctl_mutex);
1371 static const struct block_device_operations lo_fops = {
1372 .owner = THIS_MODULE,
1374 .release = lo_release,
1376 #ifdef CONFIG_COMPAT
1377 .compat_ioctl = lo_compat_ioctl,
1382 * And now the modules code and kernel interface.
1384 static int max_loop;
1385 module_param(max_loop, int, S_IRUGO);
1386 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1387 module_param(max_part, int, S_IRUGO);
1388 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1389 MODULE_LICENSE("GPL");
1390 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1392 int loop_register_transfer(struct loop_func_table *funcs)
1394 unsigned int n = funcs->number;
1396 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1398 xfer_funcs[n] = funcs;
1402 static int unregister_transfer_cb(int id, void *ptr, void *data)
1404 struct loop_device *lo = ptr;
1405 struct loop_func_table *xfer = data;
1407 mutex_lock(&lo->lo_ctl_mutex);
1408 if (lo->lo_encryption == xfer)
1409 loop_release_xfer(lo);
1410 mutex_unlock(&lo->lo_ctl_mutex);
1414 int loop_unregister_transfer(int number)
1416 unsigned int n = number;
1417 struct loop_func_table *xfer;
1419 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1422 xfer_funcs[n] = NULL;
1423 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1427 EXPORT_SYMBOL(loop_register_transfer);
1428 EXPORT_SYMBOL(loop_unregister_transfer);
1430 static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
1431 const struct blk_mq_queue_data *bd)
1433 struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
1434 struct loop_device *lo = cmd->rq->q->queuedata;
1436 blk_mq_start_request(bd->rq);
1438 if (lo->lo_state != Lo_bound)
1441 if (cmd->rq->cmd_flags & REQ_WRITE) {
1442 struct loop_device *lo = cmd->rq->q->queuedata;
1443 bool need_sched = true;
1445 spin_lock_irq(&lo->lo_lock);
1446 if (lo->write_started)
1449 lo->write_started = true;
1450 list_add_tail(&cmd->list, &lo->write_cmd_head);
1451 spin_unlock_irq(&lo->lo_lock);
1454 queue_work(lo->wq, &lo->write_work);
1456 queue_work(lo->wq, &cmd->read_work);
1459 return BLK_MQ_RQ_QUEUE_OK;
1462 static void loop_handle_cmd(struct loop_cmd *cmd)
1464 const bool write = cmd->rq->cmd_flags & REQ_WRITE;
1465 struct loop_device *lo = cmd->rq->q->queuedata;
1468 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
1471 ret = do_req_filebacked(lo, cmd->rq);
1475 cmd->rq->errors = -EIO;
1476 blk_mq_complete_request(cmd->rq);
1479 static void loop_queue_write_work(struct work_struct *work)
1481 struct loop_device *lo =
1482 container_of(work, struct loop_device, write_work);
1483 LIST_HEAD(cmd_list);
1485 spin_lock_irq(&lo->lo_lock);
1487 list_splice_init(&lo->write_cmd_head, &cmd_list);
1488 spin_unlock_irq(&lo->lo_lock);
1490 while (!list_empty(&cmd_list)) {
1491 struct loop_cmd *cmd = list_first_entry(&cmd_list,
1492 struct loop_cmd, list);
1493 list_del_init(&cmd->list);
1494 loop_handle_cmd(cmd);
1497 spin_lock_irq(&lo->lo_lock);
1498 if (!list_empty(&lo->write_cmd_head))
1500 lo->write_started = false;
1501 spin_unlock_irq(&lo->lo_lock);
1504 static void loop_queue_read_work(struct work_struct *work)
1506 struct loop_cmd *cmd =
1507 container_of(work, struct loop_cmd, read_work);
1509 loop_handle_cmd(cmd);
1512 static int loop_init_request(void *data, struct request *rq,
1513 unsigned int hctx_idx, unsigned int request_idx,
1514 unsigned int numa_node)
1516 struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
1519 INIT_WORK(&cmd->read_work, loop_queue_read_work);
1524 static struct blk_mq_ops loop_mq_ops = {
1525 .queue_rq = loop_queue_rq,
1526 .map_queue = blk_mq_map_queue,
1527 .init_request = loop_init_request,
1530 static int loop_add(struct loop_device **l, int i)
1532 struct loop_device *lo;
1533 struct gendisk *disk;
1537 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1541 lo->lo_state = Lo_unbound;
1543 /* allocate id, if @id >= 0, we're requesting that specific id */
1545 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1549 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1556 lo->tag_set.ops = &loop_mq_ops;
1557 lo->tag_set.nr_hw_queues = 1;
1558 lo->tag_set.queue_depth = 128;
1559 lo->tag_set.numa_node = NUMA_NO_NODE;
1560 lo->tag_set.cmd_size = sizeof(struct loop_cmd);
1561 lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
1562 lo->tag_set.driver_data = lo;
1564 err = blk_mq_alloc_tag_set(&lo->tag_set);
1568 lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
1569 if (IS_ERR_OR_NULL(lo->lo_queue)) {
1570 err = PTR_ERR(lo->lo_queue);
1571 goto out_cleanup_tags;
1573 lo->lo_queue->queuedata = lo;
1575 INIT_LIST_HEAD(&lo->write_cmd_head);
1576 INIT_WORK(&lo->write_work, loop_queue_write_work);
1578 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1580 goto out_free_queue;
1583 * Disable partition scanning by default. The in-kernel partition
1584 * scanning can be requested individually per-device during its
1585 * setup. Userspace can always add and remove partitions from all
1586 * devices. The needed partition minors are allocated from the
1587 * extended minor space, the main loop device numbers will continue
1588 * to match the loop minors, regardless of the number of partitions
1591 * If max_part is given, partition scanning is globally enabled for
1592 * all loop devices. The minors for the main loop devices will be
1593 * multiples of max_part.
1595 * Note: Global-for-all-devices, set-only-at-init, read-only module
1596 * parameteters like 'max_loop' and 'max_part' make things needlessly
1597 * complicated, are too static, inflexible and may surprise
1598 * userspace tools. Parameters like this in general should be avoided.
1601 disk->flags |= GENHD_FL_NO_PART_SCAN;
1602 disk->flags |= GENHD_FL_EXT_DEVT;
1603 mutex_init(&lo->lo_ctl_mutex);
1605 spin_lock_init(&lo->lo_lock);
1606 disk->major = LOOP_MAJOR;
1607 disk->first_minor = i << part_shift;
1608 disk->fops = &lo_fops;
1609 disk->private_data = lo;
1610 disk->queue = lo->lo_queue;
1611 sprintf(disk->disk_name, "loop%d", i);
1614 return lo->lo_number;
1617 blk_cleanup_queue(lo->lo_queue);
1619 blk_mq_free_tag_set(&lo->tag_set);
1621 idr_remove(&loop_index_idr, i);
1628 static void loop_remove(struct loop_device *lo)
1630 del_gendisk(lo->lo_disk);
1631 blk_cleanup_queue(lo->lo_queue);
1632 blk_mq_free_tag_set(&lo->tag_set);
1633 put_disk(lo->lo_disk);
1637 static int find_free_cb(int id, void *ptr, void *data)
1639 struct loop_device *lo = ptr;
1640 struct loop_device **l = data;
1642 if (lo->lo_state == Lo_unbound) {
1649 static int loop_lookup(struct loop_device **l, int i)
1651 struct loop_device *lo;
1657 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1660 ret = lo->lo_number;
1665 /* lookup and return a specific i */
1666 lo = idr_find(&loop_index_idr, i);
1669 ret = lo->lo_number;
1675 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1677 struct loop_device *lo;
1678 struct kobject *kobj;
1681 mutex_lock(&loop_index_mutex);
1682 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1684 err = loop_add(&lo, MINOR(dev) >> part_shift);
1688 kobj = get_disk(lo->lo_disk);
1689 mutex_unlock(&loop_index_mutex);
1695 static long loop_control_ioctl(struct file *file, unsigned int cmd,
1698 struct loop_device *lo;
1701 mutex_lock(&loop_index_mutex);
1704 ret = loop_lookup(&lo, parm);
1709 ret = loop_add(&lo, parm);
1711 case LOOP_CTL_REMOVE:
1712 ret = loop_lookup(&lo, parm);
1715 mutex_lock(&lo->lo_ctl_mutex);
1716 if (lo->lo_state != Lo_unbound) {
1718 mutex_unlock(&lo->lo_ctl_mutex);
1721 if (lo->lo_refcnt > 0) {
1723 mutex_unlock(&lo->lo_ctl_mutex);
1726 lo->lo_disk->private_data = NULL;
1727 mutex_unlock(&lo->lo_ctl_mutex);
1728 idr_remove(&loop_index_idr, lo->lo_number);
1731 case LOOP_CTL_GET_FREE:
1732 ret = loop_lookup(&lo, -1);
1735 ret = loop_add(&lo, -1);
1737 mutex_unlock(&loop_index_mutex);
1742 static const struct file_operations loop_ctl_fops = {
1743 .open = nonseekable_open,
1744 .unlocked_ioctl = loop_control_ioctl,
1745 .compat_ioctl = loop_control_ioctl,
1746 .owner = THIS_MODULE,
1747 .llseek = noop_llseek,
1750 static struct miscdevice loop_misc = {
1751 .minor = LOOP_CTRL_MINOR,
1752 .name = "loop-control",
1753 .fops = &loop_ctl_fops,
1756 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1757 MODULE_ALIAS("devname:loop-control");
1759 static int __init loop_init(void)
1762 unsigned long range;
1763 struct loop_device *lo;
1766 err = misc_register(&loop_misc);
1772 part_shift = fls(max_part);
1775 * Adjust max_part according to part_shift as it is exported
1776 * to user space so that user can decide correct minor number
1777 * if [s]he want to create more devices.
1779 * Note that -1 is required because partition 0 is reserved
1780 * for the whole disk.
1782 max_part = (1UL << part_shift) - 1;
1785 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1790 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1796 * If max_loop is specified, create that many devices upfront.
1797 * This also becomes a hard limit. If max_loop is not specified,
1798 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1799 * init time. Loop devices can be requested on-demand with the
1800 * /dev/loop-control interface, or be instantiated by accessing
1801 * a 'dead' device node.
1805 range = max_loop << part_shift;
1807 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1808 range = 1UL << MINORBITS;
1811 if (register_blkdev(LOOP_MAJOR, "loop")) {
1816 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1817 THIS_MODULE, loop_probe, NULL, NULL);
1819 /* pre-create number of devices given by config or max_loop */
1820 mutex_lock(&loop_index_mutex);
1821 for (i = 0; i < nr; i++)
1823 mutex_unlock(&loop_index_mutex);
1825 printk(KERN_INFO "loop: module loaded\n");
1829 misc_deregister(&loop_misc);
1833 static int loop_exit_cb(int id, void *ptr, void *data)
1835 struct loop_device *lo = ptr;
1841 static void __exit loop_exit(void)
1843 unsigned long range;
1845 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1847 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1848 idr_destroy(&loop_index_idr);
1850 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1851 unregister_blkdev(LOOP_MAJOR, "loop");
1853 misc_deregister(&loop_misc);
1856 module_init(loop_init);
1857 module_exit(loop_exit);
1860 static int __init max_loop_setup(char *str)
1862 max_loop = simple_strtol(str, NULL, 0);
1866 __setup("max_loop=", max_loop_setup);