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/loop.h>
67 #include <linux/compat.h>
68 #include <linux/suspend.h>
69 #include <linux/freezer.h>
70 #include <linux/mutex.h>
71 #include <linux/writeback.h>
72 #include <linux/completion.h>
73 #include <linux/highmem.h>
74 #include <linux/kthread.h>
75 #include <linux/splice.h>
76 #include <linux/sysfs.h>
77 #include <linux/miscdevice.h>
78 #include <linux/falloc.h>
80 #include <asm/uaccess.h>
82 static DEFINE_IDR(loop_index_idr);
83 static DEFINE_MUTEX(loop_index_mutex);
86 static int part_shift;
91 static int transfer_none(struct loop_device *lo, int cmd,
92 struct page *raw_page, unsigned raw_off,
93 struct page *loop_page, unsigned loop_off,
94 int size, sector_t real_block)
96 char *raw_buf = kmap_atomic(raw_page) + raw_off;
97 char *loop_buf = kmap_atomic(loop_page) + loop_off;
100 memcpy(loop_buf, raw_buf, size);
102 memcpy(raw_buf, loop_buf, size);
104 kunmap_atomic(loop_buf);
105 kunmap_atomic(raw_buf);
110 static int transfer_xor(struct loop_device *lo, int cmd,
111 struct page *raw_page, unsigned raw_off,
112 struct page *loop_page, unsigned loop_off,
113 int size, sector_t real_block)
115 char *raw_buf = kmap_atomic(raw_page) + raw_off;
116 char *loop_buf = kmap_atomic(loop_page) + loop_off;
117 char *in, *out, *key;
128 key = lo->lo_encrypt_key;
129 keysize = lo->lo_encrypt_key_size;
130 for (i = 0; i < size; i++)
131 *out++ = *in++ ^ key[(i & 511) % keysize];
133 kunmap_atomic(loop_buf);
134 kunmap_atomic(raw_buf);
139 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
141 if (unlikely(info->lo_encrypt_key_size <= 0))
146 static struct loop_func_table none_funcs = {
147 .number = LO_CRYPT_NONE,
148 .transfer = transfer_none,
151 static struct loop_func_table xor_funcs = {
152 .number = LO_CRYPT_XOR,
153 .transfer = transfer_xor,
157 /* xfer_funcs[0] is special - its release function is never called */
158 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
163 static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
167 /* Compute loopsize in bytes */
168 loopsize = i_size_read(file->f_mapping->host);
171 /* offset is beyond i_size, weird but possible */
175 if (sizelimit > 0 && sizelimit < loopsize)
176 loopsize = sizelimit;
178 * Unfortunately, if we want to do I/O on the device,
179 * the number of 512-byte sectors has to fit into a sector_t.
181 return loopsize >> 9;
184 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
186 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
190 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
192 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
193 sector_t x = (sector_t)size;
194 struct block_device *bdev = lo->lo_device;
196 if (unlikely((loff_t)x != size))
198 if (lo->lo_offset != offset)
199 lo->lo_offset = offset;
200 if (lo->lo_sizelimit != sizelimit)
201 lo->lo_sizelimit = sizelimit;
202 set_capacity(lo->lo_disk, x);
203 bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
204 /* let user-space know about the new size */
205 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
210 lo_do_transfer(struct loop_device *lo, int cmd,
211 struct page *rpage, unsigned roffs,
212 struct page *lpage, unsigned loffs,
213 int size, sector_t rblock)
215 if (unlikely(!lo->transfer))
218 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
222 * __do_lo_send_write - helper for writing data to a loop device
224 * This helper just factors out common code between do_lo_send_direct_write()
225 * and do_lo_send_write().
227 static int __do_lo_send_write(struct file *file,
228 u8 *buf, const int len, loff_t pos)
231 mm_segment_t old_fs = get_fs();
234 bw = file->f_op->write(file, buf, len, &pos);
236 if (likely(bw == len))
238 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
239 (unsigned long long)pos, len);
246 * do_lo_send_direct_write - helper for writing data to a loop device
248 * This is the fast, non-transforming version that does not need double
251 static int do_lo_send_direct_write(struct loop_device *lo,
252 struct bio_vec *bvec, loff_t pos, struct page *page)
254 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
255 kmap(bvec->bv_page) + bvec->bv_offset,
257 kunmap(bvec->bv_page);
263 * do_lo_send_write - helper for writing data to a loop device
265 * This is the slow, transforming version that needs to double buffer the
266 * data as it cannot do the transformations in place without having direct
267 * access to the destination pages of the backing file.
269 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
270 loff_t pos, struct page *page)
272 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
273 bvec->bv_offset, bvec->bv_len, pos >> 9);
275 return __do_lo_send_write(lo->lo_backing_file,
276 page_address(page), bvec->bv_len,
278 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
279 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
285 static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
287 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
289 struct bio_vec *bvec;
290 struct page *page = NULL;
293 if (lo->transfer != transfer_none) {
294 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
298 do_lo_send = do_lo_send_write;
300 do_lo_send = do_lo_send_direct_write;
303 bio_for_each_segment(bvec, bio, i) {
304 ret = do_lo_send(lo, bvec, pos, page);
316 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
321 struct lo_read_data {
322 struct loop_device *lo;
329 lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
330 struct splice_desc *sd)
332 struct lo_read_data *p = sd->u.data;
333 struct loop_device *lo = p->lo;
334 struct page *page = buf->page;
338 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
344 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
345 printk(KERN_ERR "loop: transfer error block %ld\n",
350 flush_dcache_page(p->page);
359 lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
361 return __splice_from_pipe(pipe, sd, lo_splice_actor);
365 do_lo_receive(struct loop_device *lo,
366 struct bio_vec *bvec, int bsize, loff_t pos)
368 struct lo_read_data cookie;
369 struct splice_desc sd;
374 cookie.page = bvec->bv_page;
375 cookie.offset = bvec->bv_offset;
376 cookie.bsize = bsize;
379 sd.total_len = bvec->bv_len;
384 file = lo->lo_backing_file;
385 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
391 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
393 struct bio_vec *bvec;
397 bio_for_each_segment(bvec, bio, i) {
398 s = do_lo_receive(lo, bvec, bsize, pos);
402 if (s != bvec->bv_len) {
411 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
416 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
418 if (bio_rw(bio) == WRITE) {
419 struct file *file = lo->lo_backing_file;
421 if (bio->bi_rw & REQ_FLUSH) {
422 ret = vfs_fsync(file, 0);
423 if (unlikely(ret && ret != -EINVAL)) {
430 * We use punch hole to reclaim the free space used by the
431 * image a.k.a. discard. However we do not support discard if
432 * encryption is enabled, because it may give an attacker
433 * useful information.
435 if (bio->bi_rw & REQ_DISCARD) {
436 struct file *file = lo->lo_backing_file;
437 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
439 if ((!file->f_op->fallocate) ||
440 lo->lo_encrypt_key_size) {
444 ret = file->f_op->fallocate(file, mode, pos,
446 if (unlikely(ret && ret != -EINVAL &&
452 ret = lo_send(lo, bio, pos);
454 if ((bio->bi_rw & REQ_FUA) && !ret) {
455 ret = vfs_fsync(file, 0);
456 if (unlikely(ret && ret != -EINVAL))
460 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
467 * Add bio to back of pending list
469 static void loop_add_bio(struct loop_device *lo, struct bio *bio)
472 bio_list_add(&lo->lo_bio_list, bio);
476 * Grab first pending buffer
478 static struct bio *loop_get_bio(struct loop_device *lo)
481 return bio_list_pop(&lo->lo_bio_list);
484 static void loop_make_request(struct request_queue *q, struct bio *old_bio)
486 struct loop_device *lo = q->queuedata;
487 int rw = bio_rw(old_bio);
492 BUG_ON(!lo || (rw != READ && rw != WRITE));
494 spin_lock_irq(&lo->lo_lock);
495 if (lo->lo_state != Lo_bound)
497 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
499 if (lo->lo_bio_count >= q->nr_congestion_on)
500 wait_event_lock_irq(lo->lo_req_wait,
501 lo->lo_bio_count < q->nr_congestion_off,
503 loop_add_bio(lo, old_bio);
504 wake_up(&lo->lo_event);
505 spin_unlock_irq(&lo->lo_lock);
509 spin_unlock_irq(&lo->lo_lock);
510 bio_io_error(old_bio);
513 struct switch_request {
515 struct completion wait;
518 static void do_loop_switch(struct loop_device *, struct switch_request *);
520 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
522 if (unlikely(!bio->bi_bdev)) {
523 do_loop_switch(lo, bio->bi_private);
526 int ret = do_bio_filebacked(lo, bio);
532 * worker thread that handles reads/writes to file backed loop devices,
533 * to avoid blocking in our make_request_fn. it also does loop decrypting
534 * on reads for block backed loop, as that is too heavy to do from
535 * b_end_io context where irqs may be disabled.
537 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
538 * calling kthread_stop(). Therefore once kthread_should_stop() is
539 * true, make_request will not place any more requests. Therefore
540 * once kthread_should_stop() is true and lo_bio is NULL, we are
541 * done with the loop.
543 static int loop_thread(void *data)
545 struct loop_device *lo = data;
548 set_user_nice(current, -20);
550 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
552 wait_event_interruptible(lo->lo_event,
553 !bio_list_empty(&lo->lo_bio_list) ||
554 kthread_should_stop());
556 if (bio_list_empty(&lo->lo_bio_list))
558 spin_lock_irq(&lo->lo_lock);
559 bio = loop_get_bio(lo);
560 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
561 wake_up(&lo->lo_req_wait);
562 spin_unlock_irq(&lo->lo_lock);
565 loop_handle_bio(lo, bio);
572 * loop_switch performs the hard work of switching a backing store.
573 * First it needs to flush existing IO, it does this by sending a magic
574 * BIO down the pipe. The completion of this BIO does the actual switch.
576 static int loop_switch(struct loop_device *lo, struct file *file)
578 struct switch_request w;
579 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
582 init_completion(&w.wait);
584 bio->bi_private = &w;
586 loop_make_request(lo->lo_queue, bio);
587 wait_for_completion(&w.wait);
592 * Helper to flush the IOs in loop, but keeping loop thread running
594 static int loop_flush(struct loop_device *lo)
596 /* loop not yet configured, no running thread, nothing to flush */
600 return loop_switch(lo, NULL);
604 * Do the actual switch; called from the BIO completion routine
606 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
608 struct file *file = p->file;
609 struct file *old_file = lo->lo_backing_file;
610 struct address_space *mapping;
612 /* if no new file, only flush of queued bios requested */
616 mapping = file->f_mapping;
617 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
618 lo->lo_backing_file = file;
619 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
620 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
621 lo->old_gfp_mask = mapping_gfp_mask(mapping);
622 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
629 * loop_change_fd switched the backing store of a loopback device to
630 * a new file. This is useful for operating system installers to free up
631 * the original file and in High Availability environments to switch to
632 * an alternative location for the content in case of server meltdown.
633 * This can only work if the loop device is used read-only, and if the
634 * new backing store is the same size and type as the old backing store.
636 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
639 struct file *file, *old_file;
644 if (lo->lo_state != Lo_bound)
647 /* the loop device has to be read-only */
649 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
657 inode = file->f_mapping->host;
658 old_file = lo->lo_backing_file;
662 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
665 /* size of the new backing store needs to be the same */
666 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
670 error = loop_switch(lo, file);
675 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
676 ioctl_by_bdev(bdev, BLKRRPART, 0);
685 static inline int is_loop_device(struct file *file)
687 struct inode *i = file->f_mapping->host;
689 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
692 /* loop sysfs attributes */
694 static ssize_t loop_attr_show(struct device *dev, char *page,
695 ssize_t (*callback)(struct loop_device *, char *))
697 struct gendisk *disk = dev_to_disk(dev);
698 struct loop_device *lo = disk->private_data;
700 return callback(lo, page);
703 #define LOOP_ATTR_RO(_name) \
704 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
705 static ssize_t loop_attr_do_show_##_name(struct device *d, \
706 struct device_attribute *attr, char *b) \
708 return loop_attr_show(d, b, loop_attr_##_name##_show); \
710 static struct device_attribute loop_attr_##_name = \
711 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
713 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
718 spin_lock_irq(&lo->lo_lock);
719 if (lo->lo_backing_file)
720 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
721 spin_unlock_irq(&lo->lo_lock);
723 if (IS_ERR_OR_NULL(p))
727 memmove(buf, p, ret);
735 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
737 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
740 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
742 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
745 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
747 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
749 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
752 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
754 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
756 return sprintf(buf, "%s\n", partscan ? "1" : "0");
759 LOOP_ATTR_RO(backing_file);
760 LOOP_ATTR_RO(offset);
761 LOOP_ATTR_RO(sizelimit);
762 LOOP_ATTR_RO(autoclear);
763 LOOP_ATTR_RO(partscan);
765 static struct attribute *loop_attrs[] = {
766 &loop_attr_backing_file.attr,
767 &loop_attr_offset.attr,
768 &loop_attr_sizelimit.attr,
769 &loop_attr_autoclear.attr,
770 &loop_attr_partscan.attr,
774 static struct attribute_group loop_attribute_group = {
779 static int loop_sysfs_init(struct loop_device *lo)
781 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
782 &loop_attribute_group);
785 static void loop_sysfs_exit(struct loop_device *lo)
787 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
788 &loop_attribute_group);
791 static void loop_config_discard(struct loop_device *lo)
793 struct file *file = lo->lo_backing_file;
794 struct inode *inode = file->f_mapping->host;
795 struct request_queue *q = lo->lo_queue;
798 * We use punch hole to reclaim the free space used by the
799 * image a.k.a. discard. However we do support discard if
800 * encryption is enabled, because it may give an attacker
801 * useful information.
803 if ((!file->f_op->fallocate) ||
804 lo->lo_encrypt_key_size) {
805 q->limits.discard_granularity = 0;
806 q->limits.discard_alignment = 0;
807 q->limits.max_discard_sectors = 0;
808 q->limits.discard_zeroes_data = 0;
809 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
813 q->limits.discard_granularity = inode->i_sb->s_blocksize;
814 q->limits.discard_alignment = 0;
815 q->limits.max_discard_sectors = UINT_MAX >> 9;
816 q->limits.discard_zeroes_data = 1;
817 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
820 static int loop_set_fd(struct loop_device *lo, fmode_t mode,
821 struct block_device *bdev, unsigned int arg)
823 struct file *file, *f;
825 struct address_space *mapping;
826 unsigned lo_blocksize;
831 /* This is safe, since we have a reference from open(). */
832 __module_get(THIS_MODULE);
840 if (lo->lo_state != Lo_unbound)
843 /* Avoid recursion */
845 while (is_loop_device(f)) {
846 struct loop_device *l;
848 if (f->f_mapping->host->i_bdev == bdev)
851 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
852 if (l->lo_state == Lo_unbound) {
856 f = l->lo_backing_file;
859 mapping = file->f_mapping;
860 inode = mapping->host;
863 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
866 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
868 lo_flags |= LO_FLAGS_READ_ONLY;
870 lo_blocksize = S_ISBLK(inode->i_mode) ?
871 inode->i_bdev->bd_block_size : PAGE_SIZE;
874 size = get_loop_size(lo, file);
875 if ((loff_t)(sector_t)size != size)
880 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
882 lo->lo_blocksize = lo_blocksize;
883 lo->lo_device = bdev;
884 lo->lo_flags = lo_flags;
885 lo->lo_backing_file = file;
886 lo->transfer = transfer_none;
888 lo->lo_sizelimit = 0;
889 lo->lo_bio_count = 0;
890 lo->old_gfp_mask = mapping_gfp_mask(mapping);
891 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
893 bio_list_init(&lo->lo_bio_list);
896 * set queue make_request_fn, and add limits based on lower level
899 blk_queue_make_request(lo->lo_queue, loop_make_request);
900 lo->lo_queue->queuedata = lo;
902 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
903 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
905 set_capacity(lo->lo_disk, size);
906 bd_set_size(bdev, size << 9);
908 /* let user-space know about the new size */
909 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
911 set_blocksize(bdev, lo_blocksize);
913 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
915 if (IS_ERR(lo->lo_thread)) {
916 error = PTR_ERR(lo->lo_thread);
919 lo->lo_state = Lo_bound;
920 wake_up_process(lo->lo_thread);
922 lo->lo_flags |= LO_FLAGS_PARTSCAN;
923 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
924 ioctl_by_bdev(bdev, BLKRRPART, 0);
929 lo->lo_thread = NULL;
930 lo->lo_device = NULL;
931 lo->lo_backing_file = NULL;
933 set_capacity(lo->lo_disk, 0);
934 invalidate_bdev(bdev);
935 bd_set_size(bdev, 0);
936 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
937 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
938 lo->lo_state = Lo_unbound;
942 /* This is safe: open() is still holding a reference. */
943 module_put(THIS_MODULE);
948 loop_release_xfer(struct loop_device *lo)
951 struct loop_func_table *xfer = lo->lo_encryption;
955 err = xfer->release(lo);
957 lo->lo_encryption = NULL;
958 module_put(xfer->owner);
964 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
965 const struct loop_info64 *i)
970 struct module *owner = xfer->owner;
972 if (!try_module_get(owner))
975 err = xfer->init(lo, i);
979 lo->lo_encryption = xfer;
984 static int loop_clr_fd(struct loop_device *lo)
986 struct file *filp = lo->lo_backing_file;
987 gfp_t gfp = lo->old_gfp_mask;
988 struct block_device *bdev = lo->lo_device;
990 if (lo->lo_state != Lo_bound)
994 * If we've explicitly asked to tear down the loop device,
995 * and it has an elevated reference count, set it for auto-teardown when
996 * the last reference goes away. This stops $!~#$@ udev from
997 * preventing teardown because it decided that it needs to run blkid on
998 * the loopback device whenever they appear. xfstests is notorious for
999 * failing tests because blkid via udev races with a losetup
1000 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1001 * command to fail with EBUSY.
1003 if (lo->lo_refcnt > 1) {
1004 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1005 mutex_unlock(&lo->lo_ctl_mutex);
1012 spin_lock_irq(&lo->lo_lock);
1013 lo->lo_state = Lo_rundown;
1014 spin_unlock_irq(&lo->lo_lock);
1016 kthread_stop(lo->lo_thread);
1018 spin_lock_irq(&lo->lo_lock);
1019 lo->lo_backing_file = NULL;
1020 spin_unlock_irq(&lo->lo_lock);
1022 loop_release_xfer(lo);
1023 lo->transfer = NULL;
1025 lo->lo_device = NULL;
1026 lo->lo_encryption = NULL;
1028 lo->lo_sizelimit = 0;
1029 lo->lo_encrypt_key_size = 0;
1030 lo->lo_thread = NULL;
1031 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1032 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1033 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1035 invalidate_bdev(bdev);
1036 set_capacity(lo->lo_disk, 0);
1037 loop_sysfs_exit(lo);
1039 bd_set_size(bdev, 0);
1040 /* let user-space know about this change */
1041 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1043 mapping_set_gfp_mask(filp->f_mapping, gfp);
1044 lo->lo_state = Lo_unbound;
1045 /* This is safe: open() is still holding a reference. */
1046 module_put(THIS_MODULE);
1047 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1048 ioctl_by_bdev(bdev, BLKRRPART, 0);
1051 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1052 mutex_unlock(&lo->lo_ctl_mutex);
1054 * Need not hold lo_ctl_mutex to fput backing file.
1055 * Calling fput holding lo_ctl_mutex triggers a circular
1056 * lock dependency possibility warning as fput can take
1057 * bd_mutex which is usually taken before lo_ctl_mutex.
1064 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1067 struct loop_func_table *xfer;
1068 kuid_t uid = current_uid();
1070 if (lo->lo_encrypt_key_size &&
1071 !uid_eq(lo->lo_key_owner, uid) &&
1072 !capable(CAP_SYS_ADMIN))
1074 if (lo->lo_state != Lo_bound)
1076 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1079 err = loop_release_xfer(lo);
1083 if (info->lo_encrypt_type) {
1084 unsigned int type = info->lo_encrypt_type;
1086 if (type >= MAX_LO_CRYPT)
1088 xfer = xfer_funcs[type];
1094 err = loop_init_xfer(lo, xfer, info);
1098 if (lo->lo_offset != info->lo_offset ||
1099 lo->lo_sizelimit != info->lo_sizelimit)
1100 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1103 loop_config_discard(lo);
1105 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1106 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1107 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1108 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1112 lo->transfer = xfer->transfer;
1113 lo->ioctl = xfer->ioctl;
1115 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1116 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1117 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1119 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1120 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1121 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1122 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1123 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1126 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1127 lo->lo_init[0] = info->lo_init[0];
1128 lo->lo_init[1] = info->lo_init[1];
1129 if (info->lo_encrypt_key_size) {
1130 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1131 info->lo_encrypt_key_size);
1132 lo->lo_key_owner = uid;
1139 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1141 struct file *file = lo->lo_backing_file;
1145 if (lo->lo_state != Lo_bound)
1147 error = vfs_getattr(&file->f_path, &stat);
1150 memset(info, 0, sizeof(*info));
1151 info->lo_number = lo->lo_number;
1152 info->lo_device = huge_encode_dev(stat.dev);
1153 info->lo_inode = stat.ino;
1154 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1155 info->lo_offset = lo->lo_offset;
1156 info->lo_sizelimit = lo->lo_sizelimit;
1157 info->lo_flags = lo->lo_flags;
1158 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1159 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1160 info->lo_encrypt_type =
1161 lo->lo_encryption ? lo->lo_encryption->number : 0;
1162 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1163 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1164 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1165 lo->lo_encrypt_key_size);
1171 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1173 memset(info64, 0, sizeof(*info64));
1174 info64->lo_number = info->lo_number;
1175 info64->lo_device = info->lo_device;
1176 info64->lo_inode = info->lo_inode;
1177 info64->lo_rdevice = info->lo_rdevice;
1178 info64->lo_offset = info->lo_offset;
1179 info64->lo_sizelimit = 0;
1180 info64->lo_encrypt_type = info->lo_encrypt_type;
1181 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1182 info64->lo_flags = info->lo_flags;
1183 info64->lo_init[0] = info->lo_init[0];
1184 info64->lo_init[1] = info->lo_init[1];
1185 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1186 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1188 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1189 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1193 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1195 memset(info, 0, sizeof(*info));
1196 info->lo_number = info64->lo_number;
1197 info->lo_device = info64->lo_device;
1198 info->lo_inode = info64->lo_inode;
1199 info->lo_rdevice = info64->lo_rdevice;
1200 info->lo_offset = info64->lo_offset;
1201 info->lo_encrypt_type = info64->lo_encrypt_type;
1202 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1203 info->lo_flags = info64->lo_flags;
1204 info->lo_init[0] = info64->lo_init[0];
1205 info->lo_init[1] = info64->lo_init[1];
1206 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1207 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1209 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1210 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1212 /* error in case values were truncated */
1213 if (info->lo_device != info64->lo_device ||
1214 info->lo_rdevice != info64->lo_rdevice ||
1215 info->lo_inode != info64->lo_inode ||
1216 info->lo_offset != info64->lo_offset)
1223 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1225 struct loop_info info;
1226 struct loop_info64 info64;
1228 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1230 loop_info64_from_old(&info, &info64);
1231 return loop_set_status(lo, &info64);
1235 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1237 struct loop_info64 info64;
1239 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1241 return loop_set_status(lo, &info64);
1245 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1246 struct loop_info info;
1247 struct loop_info64 info64;
1253 err = loop_get_status(lo, &info64);
1255 err = loop_info64_to_old(&info64, &info);
1256 if (!err && copy_to_user(arg, &info, sizeof(info)))
1263 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1264 struct loop_info64 info64;
1270 err = loop_get_status(lo, &info64);
1271 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1277 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1279 if (unlikely(lo->lo_state != Lo_bound))
1282 return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1285 static int lo_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;
1291 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1294 err = loop_set_fd(lo, mode, bdev, arg);
1296 case LOOP_CHANGE_FD:
1297 err = loop_change_fd(lo, bdev, arg);
1300 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1301 err = loop_clr_fd(lo);
1305 case LOOP_SET_STATUS:
1307 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1308 err = loop_set_status_old(lo,
1309 (struct loop_info __user *)arg);
1311 case LOOP_GET_STATUS:
1312 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1314 case LOOP_SET_STATUS64:
1316 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1317 err = loop_set_status64(lo,
1318 (struct loop_info64 __user *) arg);
1320 case LOOP_GET_STATUS64:
1321 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1323 case LOOP_SET_CAPACITY:
1325 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1326 err = loop_set_capacity(lo, bdev);
1329 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1331 mutex_unlock(&lo->lo_ctl_mutex);
1337 #ifdef CONFIG_COMPAT
1338 struct compat_loop_info {
1339 compat_int_t lo_number; /* ioctl r/o */
1340 compat_dev_t lo_device; /* ioctl r/o */
1341 compat_ulong_t lo_inode; /* ioctl r/o */
1342 compat_dev_t lo_rdevice; /* ioctl r/o */
1343 compat_int_t lo_offset;
1344 compat_int_t lo_encrypt_type;
1345 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1346 compat_int_t lo_flags; /* ioctl r/o */
1347 char lo_name[LO_NAME_SIZE];
1348 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1349 compat_ulong_t lo_init[2];
1354 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1355 * - noinlined to reduce stack space usage in main part of driver
1358 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1359 struct loop_info64 *info64)
1361 struct compat_loop_info info;
1363 if (copy_from_user(&info, arg, sizeof(info)))
1366 memset(info64, 0, sizeof(*info64));
1367 info64->lo_number = info.lo_number;
1368 info64->lo_device = info.lo_device;
1369 info64->lo_inode = info.lo_inode;
1370 info64->lo_rdevice = info.lo_rdevice;
1371 info64->lo_offset = info.lo_offset;
1372 info64->lo_sizelimit = 0;
1373 info64->lo_encrypt_type = info.lo_encrypt_type;
1374 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1375 info64->lo_flags = info.lo_flags;
1376 info64->lo_init[0] = info.lo_init[0];
1377 info64->lo_init[1] = info.lo_init[1];
1378 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1379 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1381 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1382 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1387 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1388 * - noinlined to reduce stack space usage in main part of driver
1391 loop_info64_to_compat(const struct loop_info64 *info64,
1392 struct compat_loop_info __user *arg)
1394 struct compat_loop_info info;
1396 memset(&info, 0, sizeof(info));
1397 info.lo_number = info64->lo_number;
1398 info.lo_device = info64->lo_device;
1399 info.lo_inode = info64->lo_inode;
1400 info.lo_rdevice = info64->lo_rdevice;
1401 info.lo_offset = info64->lo_offset;
1402 info.lo_encrypt_type = info64->lo_encrypt_type;
1403 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1404 info.lo_flags = info64->lo_flags;
1405 info.lo_init[0] = info64->lo_init[0];
1406 info.lo_init[1] = info64->lo_init[1];
1407 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1408 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1410 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1411 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1413 /* error in case values were truncated */
1414 if (info.lo_device != info64->lo_device ||
1415 info.lo_rdevice != info64->lo_rdevice ||
1416 info.lo_inode != info64->lo_inode ||
1417 info.lo_offset != info64->lo_offset ||
1418 info.lo_init[0] != info64->lo_init[0] ||
1419 info.lo_init[1] != info64->lo_init[1])
1422 if (copy_to_user(arg, &info, sizeof(info)))
1428 loop_set_status_compat(struct loop_device *lo,
1429 const struct compat_loop_info __user *arg)
1431 struct loop_info64 info64;
1434 ret = loop_info64_from_compat(arg, &info64);
1437 return loop_set_status(lo, &info64);
1441 loop_get_status_compat(struct loop_device *lo,
1442 struct compat_loop_info __user *arg)
1444 struct loop_info64 info64;
1450 err = loop_get_status(lo, &info64);
1452 err = loop_info64_to_compat(&info64, arg);
1456 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1457 unsigned int cmd, unsigned long arg)
1459 struct loop_device *lo = bdev->bd_disk->private_data;
1463 case LOOP_SET_STATUS:
1464 mutex_lock(&lo->lo_ctl_mutex);
1465 err = loop_set_status_compat(
1466 lo, (const struct compat_loop_info __user *) arg);
1467 mutex_unlock(&lo->lo_ctl_mutex);
1469 case LOOP_GET_STATUS:
1470 mutex_lock(&lo->lo_ctl_mutex);
1471 err = loop_get_status_compat(
1472 lo, (struct compat_loop_info __user *) arg);
1473 mutex_unlock(&lo->lo_ctl_mutex);
1475 case LOOP_SET_CAPACITY:
1477 case LOOP_GET_STATUS64:
1478 case LOOP_SET_STATUS64:
1479 arg = (unsigned long) compat_ptr(arg);
1481 case LOOP_CHANGE_FD:
1482 err = lo_ioctl(bdev, mode, cmd, arg);
1492 static int lo_open(struct block_device *bdev, fmode_t mode)
1494 struct loop_device *lo;
1497 mutex_lock(&loop_index_mutex);
1498 lo = bdev->bd_disk->private_data;
1504 mutex_lock(&lo->lo_ctl_mutex);
1506 mutex_unlock(&lo->lo_ctl_mutex);
1508 mutex_unlock(&loop_index_mutex);
1512 static int lo_release(struct gendisk *disk, fmode_t mode)
1514 struct loop_device *lo = disk->private_data;
1517 mutex_lock(&lo->lo_ctl_mutex);
1519 if (--lo->lo_refcnt)
1522 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1524 * In autoclear mode, stop the loop thread
1525 * and remove configuration after last close.
1527 err = loop_clr_fd(lo);
1532 * Otherwise keep thread (if running) and config,
1533 * but flush possible ongoing bios in thread.
1539 mutex_unlock(&lo->lo_ctl_mutex);
1544 static const struct block_device_operations lo_fops = {
1545 .owner = THIS_MODULE,
1547 .release = lo_release,
1549 #ifdef CONFIG_COMPAT
1550 .compat_ioctl = lo_compat_ioctl,
1555 * And now the modules code and kernel interface.
1557 static int max_loop;
1558 module_param(max_loop, int, S_IRUGO);
1559 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1560 module_param(max_part, int, S_IRUGO);
1561 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1562 MODULE_LICENSE("GPL");
1563 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1565 int loop_register_transfer(struct loop_func_table *funcs)
1567 unsigned int n = funcs->number;
1569 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1571 xfer_funcs[n] = funcs;
1575 static int unregister_transfer_cb(int id, void *ptr, void *data)
1577 struct loop_device *lo = ptr;
1578 struct loop_func_table *xfer = data;
1580 mutex_lock(&lo->lo_ctl_mutex);
1581 if (lo->lo_encryption == xfer)
1582 loop_release_xfer(lo);
1583 mutex_unlock(&lo->lo_ctl_mutex);
1587 int loop_unregister_transfer(int number)
1589 unsigned int n = number;
1590 struct loop_func_table *xfer;
1592 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1595 xfer_funcs[n] = NULL;
1596 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1600 EXPORT_SYMBOL(loop_register_transfer);
1601 EXPORT_SYMBOL(loop_unregister_transfer);
1603 static int loop_add(struct loop_device **l, int i)
1605 struct loop_device *lo;
1606 struct gendisk *disk;
1610 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1614 /* allocate id, if @id >= 0, we're requesting that specific id */
1616 err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
1620 err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
1626 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1630 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1632 goto out_free_queue;
1635 * Disable partition scanning by default. The in-kernel partition
1636 * scanning can be requested individually per-device during its
1637 * setup. Userspace can always add and remove partitions from all
1638 * devices. The needed partition minors are allocated from the
1639 * extended minor space, the main loop device numbers will continue
1640 * to match the loop minors, regardless of the number of partitions
1643 * If max_part is given, partition scanning is globally enabled for
1644 * all loop devices. The minors for the main loop devices will be
1645 * multiples of max_part.
1647 * Note: Global-for-all-devices, set-only-at-init, read-only module
1648 * parameteters like 'max_loop' and 'max_part' make things needlessly
1649 * complicated, are too static, inflexible and may surprise
1650 * userspace tools. Parameters like this in general should be avoided.
1653 disk->flags |= GENHD_FL_NO_PART_SCAN;
1654 disk->flags |= GENHD_FL_EXT_DEVT;
1655 mutex_init(&lo->lo_ctl_mutex);
1657 lo->lo_thread = NULL;
1658 init_waitqueue_head(&lo->lo_event);
1659 init_waitqueue_head(&lo->lo_req_wait);
1660 spin_lock_init(&lo->lo_lock);
1661 disk->major = LOOP_MAJOR;
1662 disk->first_minor = i << part_shift;
1663 disk->fops = &lo_fops;
1664 disk->private_data = lo;
1665 disk->queue = lo->lo_queue;
1666 sprintf(disk->disk_name, "loop%d", i);
1669 return lo->lo_number;
1672 blk_cleanup_queue(lo->lo_queue);
1679 static void loop_remove(struct loop_device *lo)
1681 del_gendisk(lo->lo_disk);
1682 blk_cleanup_queue(lo->lo_queue);
1683 put_disk(lo->lo_disk);
1687 static int find_free_cb(int id, void *ptr, void *data)
1689 struct loop_device *lo = ptr;
1690 struct loop_device **l = data;
1692 if (lo->lo_state == Lo_unbound) {
1699 static int loop_lookup(struct loop_device **l, int i)
1701 struct loop_device *lo;
1707 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1710 ret = lo->lo_number;
1715 /* lookup and return a specific i */
1716 lo = idr_find(&loop_index_idr, i);
1719 ret = lo->lo_number;
1725 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1727 struct loop_device *lo;
1728 struct kobject *kobj;
1731 mutex_lock(&loop_index_mutex);
1732 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1734 err = loop_add(&lo, MINOR(dev) >> part_shift);
1736 kobj = ERR_PTR(err);
1738 kobj = get_disk(lo->lo_disk);
1739 mutex_unlock(&loop_index_mutex);
1745 static long loop_control_ioctl(struct file *file, unsigned int cmd,
1748 struct loop_device *lo;
1751 mutex_lock(&loop_index_mutex);
1754 ret = loop_lookup(&lo, parm);
1759 ret = loop_add(&lo, parm);
1761 case LOOP_CTL_REMOVE:
1762 ret = loop_lookup(&lo, parm);
1765 mutex_lock(&lo->lo_ctl_mutex);
1766 if (lo->lo_state != Lo_unbound) {
1768 mutex_unlock(&lo->lo_ctl_mutex);
1771 if (lo->lo_refcnt > 0) {
1773 mutex_unlock(&lo->lo_ctl_mutex);
1776 lo->lo_disk->private_data = NULL;
1777 mutex_unlock(&lo->lo_ctl_mutex);
1778 idr_remove(&loop_index_idr, lo->lo_number);
1781 case LOOP_CTL_GET_FREE:
1782 ret = loop_lookup(&lo, -1);
1785 ret = loop_add(&lo, -1);
1787 mutex_unlock(&loop_index_mutex);
1792 static const struct file_operations loop_ctl_fops = {
1793 .open = nonseekable_open,
1794 .unlocked_ioctl = loop_control_ioctl,
1795 .compat_ioctl = loop_control_ioctl,
1796 .owner = THIS_MODULE,
1797 .llseek = noop_llseek,
1800 static struct miscdevice loop_misc = {
1801 .minor = LOOP_CTRL_MINOR,
1802 .name = "loop-control",
1803 .fops = &loop_ctl_fops,
1806 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1807 MODULE_ALIAS("devname:loop-control");
1809 static int __init loop_init(void)
1812 unsigned long range;
1813 struct loop_device *lo;
1816 err = misc_register(&loop_misc);
1822 part_shift = fls(max_part);
1825 * Adjust max_part according to part_shift as it is exported
1826 * to user space so that user can decide correct minor number
1827 * if [s]he want to create more devices.
1829 * Note that -1 is required because partition 0 is reserved
1830 * for the whole disk.
1832 max_part = (1UL << part_shift) - 1;
1835 if ((1UL << part_shift) > DISK_MAX_PARTS) {
1840 if (max_loop > 1UL << (MINORBITS - part_shift)) {
1846 * If max_loop is specified, create that many devices upfront.
1847 * This also becomes a hard limit. If max_loop is not specified,
1848 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1849 * init time. Loop devices can be requested on-demand with the
1850 * /dev/loop-control interface, or be instantiated by accessing
1851 * a 'dead' device node.
1855 range = max_loop << part_shift;
1857 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1858 range = 1UL << MINORBITS;
1861 if (register_blkdev(LOOP_MAJOR, "loop")) {
1866 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1867 THIS_MODULE, loop_probe, NULL, NULL);
1869 /* pre-create number of devices given by config or max_loop */
1870 mutex_lock(&loop_index_mutex);
1871 for (i = 0; i < nr; i++)
1873 mutex_unlock(&loop_index_mutex);
1875 printk(KERN_INFO "loop: module loaded\n");
1879 misc_deregister(&loop_misc);
1883 static int loop_exit_cb(int id, void *ptr, void *data)
1885 struct loop_device *lo = ptr;
1891 static void __exit loop_exit(void)
1893 unsigned long range;
1895 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1897 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1898 idr_destroy(&loop_index_idr);
1900 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1901 unregister_blkdev(LOOP_MAJOR, "loop");
1903 misc_deregister(&loop_misc);
1906 module_init(loop_init);
1907 module_exit(loop_exit);
1910 static int __init max_loop_setup(char *str)
1912 max_loop = simple_strtol(str, NULL, 0);
1916 __setup("max_loop=", max_loop_setup);