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/buffer_head.h> /* for invalidate_bdev() */
73 #include <linux/completion.h>
74 #include <linux/highmem.h>
75 #include <linux/kthread.h>
76 #include <linux/splice.h>
77 #include <linux/sysfs.h>
78 #include <linux/miscdevice.h>
79 #include <linux/falloc.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;
92 static int transfer_none(struct loop_device *lo, int cmd,
93 struct page *raw_page, unsigned raw_off,
94 struct page *loop_page, unsigned loop_off,
95 int size, sector_t real_block)
97 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
98 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
101 memcpy(loop_buf, raw_buf, size);
103 memcpy(raw_buf, loop_buf, size);
105 kunmap_atomic(loop_buf, KM_USER1);
106 kunmap_atomic(raw_buf, KM_USER0);
111 static int transfer_xor(struct loop_device *lo, int cmd,
112 struct page *raw_page, unsigned raw_off,
113 struct page *loop_page, unsigned loop_off,
114 int size, sector_t real_block)
116 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
117 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
118 char *in, *out, *key;
129 key = lo->lo_encrypt_key;
130 keysize = lo->lo_encrypt_key_size;
131 for (i = 0; i < size; i++)
132 *out++ = *in++ ^ key[(i & 511) % keysize];
134 kunmap_atomic(loop_buf, KM_USER1);
135 kunmap_atomic(raw_buf, KM_USER0);
140 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
142 if (unlikely(info->lo_encrypt_key_size <= 0))
147 static struct loop_func_table none_funcs = {
148 .number = LO_CRYPT_NONE,
149 .transfer = transfer_none,
152 static struct loop_func_table xor_funcs = {
153 .number = LO_CRYPT_XOR,
154 .transfer = transfer_xor,
158 /* xfer_funcs[0] is special - its release function is never called */
159 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
164 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
166 loff_t size, offset, loopsize;
168 /* Compute loopsize in bytes */
169 size = i_size_read(file->f_mapping->host);
170 offset = lo->lo_offset;
171 loopsize = size - offset;
172 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
173 loopsize = lo->lo_sizelimit;
176 * Unfortunately, if we want to do I/O on the device,
177 * the number of 512-byte sectors has to fit into a sector_t.
179 return loopsize >> 9;
183 figure_loop_size(struct loop_device *lo)
185 loff_t size = get_loop_size(lo, lo->lo_backing_file);
186 sector_t x = (sector_t)size;
188 if (unlikely((loff_t)x != size))
191 set_capacity(lo->lo_disk, x);
196 lo_do_transfer(struct loop_device *lo, int cmd,
197 struct page *rpage, unsigned roffs,
198 struct page *lpage, unsigned loffs,
199 int size, sector_t rblock)
201 if (unlikely(!lo->transfer))
204 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
208 * __do_lo_send_write - helper for writing data to a loop device
210 * This helper just factors out common code between do_lo_send_direct_write()
211 * and do_lo_send_write().
213 static int __do_lo_send_write(struct file *file,
214 u8 *buf, const int len, loff_t pos)
217 mm_segment_t old_fs = get_fs();
220 bw = file->f_op->write(file, buf, len, &pos);
222 if (likely(bw == len))
224 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
225 (unsigned long long)pos, len);
232 * do_lo_send_direct_write - helper for writing data to a loop device
234 * This is the fast, non-transforming version that does not need double
237 static int do_lo_send_direct_write(struct loop_device *lo,
238 struct bio_vec *bvec, loff_t pos, struct page *page)
240 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
241 kmap(bvec->bv_page) + bvec->bv_offset,
243 kunmap(bvec->bv_page);
249 * do_lo_send_write - helper for writing data to a loop device
251 * This is the slow, transforming version that needs to double buffer the
252 * data as it cannot do the transformations in place without having direct
253 * access to the destination pages of the backing file.
255 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
256 loff_t pos, struct page *page)
258 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
259 bvec->bv_offset, bvec->bv_len, pos >> 9);
261 return __do_lo_send_write(lo->lo_backing_file,
262 page_address(page), bvec->bv_len,
264 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
265 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
271 static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
273 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
275 struct bio_vec *bvec;
276 struct page *page = NULL;
279 if (lo->transfer != transfer_none) {
280 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
284 do_lo_send = do_lo_send_write;
286 do_lo_send = do_lo_send_direct_write;
289 bio_for_each_segment(bvec, bio, i) {
290 ret = do_lo_send(lo, bvec, pos, page);
302 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
307 struct lo_read_data {
308 struct loop_device *lo;
315 lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
316 struct splice_desc *sd)
318 struct lo_read_data *p = sd->u.data;
319 struct loop_device *lo = p->lo;
320 struct page *page = buf->page;
324 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
330 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
331 printk(KERN_ERR "loop: transfer error block %ld\n",
336 flush_dcache_page(p->page);
345 lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
347 return __splice_from_pipe(pipe, sd, lo_splice_actor);
351 do_lo_receive(struct loop_device *lo,
352 struct bio_vec *bvec, int bsize, loff_t pos)
354 struct lo_read_data cookie;
355 struct splice_desc sd;
360 cookie.page = bvec->bv_page;
361 cookie.offset = bvec->bv_offset;
362 cookie.bsize = bsize;
365 sd.total_len = bvec->bv_len;
370 file = lo->lo_backing_file;
371 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
380 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
382 struct bio_vec *bvec;
385 bio_for_each_segment(bvec, bio, i) {
386 ret = do_lo_receive(lo, bvec, bsize, pos);
394 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
399 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
401 if (bio_rw(bio) == WRITE) {
402 struct file *file = lo->lo_backing_file;
404 if (bio->bi_rw & REQ_FLUSH) {
405 ret = vfs_fsync(file, 0);
406 if (unlikely(ret && ret != -EINVAL)) {
413 * We use punch hole to reclaim the free space used by the
414 * image a.k.a. discard. However we do support discard if
415 * encryption is enabled, because it may give an attacker
416 * useful information.
418 if (bio->bi_rw & REQ_DISCARD) {
419 struct file *file = lo->lo_backing_file;
420 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
422 if ((!file->f_op->fallocate) ||
423 lo->lo_encrypt_key_size) {
427 ret = file->f_op->fallocate(file, mode, pos,
429 if (unlikely(ret && ret != -EINVAL &&
435 ret = lo_send(lo, bio, pos);
437 if ((bio->bi_rw & REQ_FUA) && !ret) {
438 ret = vfs_fsync(file, 0);
439 if (unlikely(ret && ret != -EINVAL))
443 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
450 * Add bio to back of pending list
452 static void loop_add_bio(struct loop_device *lo, struct bio *bio)
454 bio_list_add(&lo->lo_bio_list, bio);
458 * Grab first pending buffer
460 static struct bio *loop_get_bio(struct loop_device *lo)
462 return bio_list_pop(&lo->lo_bio_list);
465 static void loop_make_request(struct request_queue *q, struct bio *old_bio)
467 struct loop_device *lo = q->queuedata;
468 int rw = bio_rw(old_bio);
473 BUG_ON(!lo || (rw != READ && rw != WRITE));
475 spin_lock_irq(&lo->lo_lock);
476 if (lo->lo_state != Lo_bound)
478 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
480 loop_add_bio(lo, old_bio);
481 wake_up(&lo->lo_event);
482 spin_unlock_irq(&lo->lo_lock);
486 spin_unlock_irq(&lo->lo_lock);
487 bio_io_error(old_bio);
490 struct switch_request {
492 struct completion wait;
495 static void do_loop_switch(struct loop_device *, struct switch_request *);
497 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
499 if (unlikely(!bio->bi_bdev)) {
500 do_loop_switch(lo, bio->bi_private);
503 int ret = do_bio_filebacked(lo, bio);
509 * worker thread that handles reads/writes to file backed loop devices,
510 * to avoid blocking in our make_request_fn. it also does loop decrypting
511 * on reads for block backed loop, as that is too heavy to do from
512 * b_end_io context where irqs may be disabled.
514 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
515 * calling kthread_stop(). Therefore once kthread_should_stop() is
516 * true, make_request will not place any more requests. Therefore
517 * once kthread_should_stop() is true and lo_bio is NULL, we are
518 * done with the loop.
520 static int loop_thread(void *data)
522 struct loop_device *lo = data;
525 set_user_nice(current, -20);
527 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
529 wait_event_interruptible(lo->lo_event,
530 !bio_list_empty(&lo->lo_bio_list) ||
531 kthread_should_stop());
533 if (bio_list_empty(&lo->lo_bio_list))
535 spin_lock_irq(&lo->lo_lock);
536 bio = loop_get_bio(lo);
537 spin_unlock_irq(&lo->lo_lock);
540 loop_handle_bio(lo, bio);
547 * loop_switch performs the hard work of switching a backing store.
548 * First it needs to flush existing IO, it does this by sending a magic
549 * BIO down the pipe. The completion of this BIO does the actual switch.
551 static int loop_switch(struct loop_device *lo, struct file *file)
553 struct switch_request w;
554 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
557 init_completion(&w.wait);
559 bio->bi_private = &w;
561 loop_make_request(lo->lo_queue, bio);
562 wait_for_completion(&w.wait);
567 * Helper to flush the IOs in loop, but keeping loop thread running
569 static int loop_flush(struct loop_device *lo)
571 /* loop not yet configured, no running thread, nothing to flush */
575 return loop_switch(lo, NULL);
579 * Do the actual switch; called from the BIO completion routine
581 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
583 struct file *file = p->file;
584 struct file *old_file = lo->lo_backing_file;
585 struct address_space *mapping;
587 /* if no new file, only flush of queued bios requested */
591 mapping = file->f_mapping;
592 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
593 lo->lo_backing_file = file;
594 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
595 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
596 lo->old_gfp_mask = mapping_gfp_mask(mapping);
597 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
604 * loop_change_fd switched the backing store of a loopback device to
605 * a new file. This is useful for operating system installers to free up
606 * the original file and in High Availability environments to switch to
607 * an alternative location for the content in case of server meltdown.
608 * This can only work if the loop device is used read-only, and if the
609 * new backing store is the same size and type as the old backing store.
611 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
614 struct file *file, *old_file;
619 if (lo->lo_state != Lo_bound)
622 /* the loop device has to be read-only */
624 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
632 inode = file->f_mapping->host;
633 old_file = lo->lo_backing_file;
637 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
640 /* size of the new backing store needs to be the same */
641 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
645 error = loop_switch(lo, file);
650 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
651 ioctl_by_bdev(bdev, BLKRRPART, 0);
660 static inline int is_loop_device(struct file *file)
662 struct inode *i = file->f_mapping->host;
664 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
667 /* loop sysfs attributes */
669 static ssize_t loop_attr_show(struct device *dev, char *page,
670 ssize_t (*callback)(struct loop_device *, char *))
672 struct gendisk *disk = dev_to_disk(dev);
673 struct loop_device *lo = disk->private_data;
675 return callback(lo, page);
678 #define LOOP_ATTR_RO(_name) \
679 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
680 static ssize_t loop_attr_do_show_##_name(struct device *d, \
681 struct device_attribute *attr, char *b) \
683 return loop_attr_show(d, b, loop_attr_##_name##_show); \
685 static struct device_attribute loop_attr_##_name = \
686 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
688 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
693 spin_lock_irq(&lo->lo_lock);
694 if (lo->lo_backing_file)
695 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
696 spin_unlock_irq(&lo->lo_lock);
698 if (IS_ERR_OR_NULL(p))
702 memmove(buf, p, ret);
710 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
712 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
715 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
717 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
720 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
722 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
724 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
727 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
729 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
731 return sprintf(buf, "%s\n", partscan ? "1" : "0");
734 LOOP_ATTR_RO(backing_file);
735 LOOP_ATTR_RO(offset);
736 LOOP_ATTR_RO(sizelimit);
737 LOOP_ATTR_RO(autoclear);
738 LOOP_ATTR_RO(partscan);
740 static struct attribute *loop_attrs[] = {
741 &loop_attr_backing_file.attr,
742 &loop_attr_offset.attr,
743 &loop_attr_sizelimit.attr,
744 &loop_attr_autoclear.attr,
745 &loop_attr_partscan.attr,
749 static struct attribute_group loop_attribute_group = {
754 static int loop_sysfs_init(struct loop_device *lo)
756 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
757 &loop_attribute_group);
760 static void loop_sysfs_exit(struct loop_device *lo)
762 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
763 &loop_attribute_group);
766 static void loop_config_discard(struct loop_device *lo)
768 struct file *file = lo->lo_backing_file;
769 struct inode *inode = file->f_mapping->host;
770 struct request_queue *q = lo->lo_queue;
773 * We use punch hole to reclaim the free space used by the
774 * image a.k.a. discard. However we do support discard if
775 * encryption is enabled, because it may give an attacker
776 * useful information.
778 if ((!file->f_op->fallocate) ||
779 lo->lo_encrypt_key_size) {
780 q->limits.discard_granularity = 0;
781 q->limits.discard_alignment = 0;
782 q->limits.max_discard_sectors = 0;
783 q->limits.discard_zeroes_data = 0;
784 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
788 q->limits.discard_granularity = inode->i_sb->s_blocksize;
789 q->limits.discard_alignment = inode->i_sb->s_blocksize;
790 q->limits.max_discard_sectors = UINT_MAX >> 9;
791 q->limits.discard_zeroes_data = 1;
792 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
795 static int loop_set_fd(struct loop_device *lo, fmode_t mode,
796 struct block_device *bdev, unsigned int arg)
798 struct file *file, *f;
800 struct address_space *mapping;
801 unsigned lo_blocksize;
806 /* This is safe, since we have a reference from open(). */
807 __module_get(THIS_MODULE);
815 if (lo->lo_state != Lo_unbound)
818 /* Avoid recursion */
820 while (is_loop_device(f)) {
821 struct loop_device *l;
823 if (f->f_mapping->host->i_bdev == bdev)
826 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
827 if (l->lo_state == Lo_unbound) {
831 f = l->lo_backing_file;
834 mapping = file->f_mapping;
835 inode = mapping->host;
838 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
841 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
843 lo_flags |= LO_FLAGS_READ_ONLY;
845 lo_blocksize = S_ISBLK(inode->i_mode) ?
846 inode->i_bdev->bd_block_size : PAGE_SIZE;
849 size = get_loop_size(lo, file);
850 if ((loff_t)(sector_t)size != size)
855 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
857 lo->lo_blocksize = lo_blocksize;
858 lo->lo_device = bdev;
859 lo->lo_flags = lo_flags;
860 lo->lo_backing_file = file;
861 lo->transfer = transfer_none;
863 lo->lo_sizelimit = 0;
864 lo->old_gfp_mask = mapping_gfp_mask(mapping);
865 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
867 bio_list_init(&lo->lo_bio_list);
870 * set queue make_request_fn, and add limits based on lower level
873 blk_queue_make_request(lo->lo_queue, loop_make_request);
874 lo->lo_queue->queuedata = lo;
876 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
877 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
879 set_capacity(lo->lo_disk, size);
880 bd_set_size(bdev, size << 9);
882 /* let user-space know about the new size */
883 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
885 set_blocksize(bdev, lo_blocksize);
887 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
889 if (IS_ERR(lo->lo_thread)) {
890 error = PTR_ERR(lo->lo_thread);
893 lo->lo_state = Lo_bound;
894 wake_up_process(lo->lo_thread);
896 lo->lo_flags |= LO_FLAGS_PARTSCAN;
897 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
898 ioctl_by_bdev(bdev, BLKRRPART, 0);
903 lo->lo_thread = NULL;
904 lo->lo_device = NULL;
905 lo->lo_backing_file = NULL;
907 set_capacity(lo->lo_disk, 0);
908 invalidate_bdev(bdev);
909 bd_set_size(bdev, 0);
910 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
911 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
912 lo->lo_state = Lo_unbound;
916 /* This is safe: open() is still holding a reference. */
917 module_put(THIS_MODULE);
922 loop_release_xfer(struct loop_device *lo)
925 struct loop_func_table *xfer = lo->lo_encryption;
929 err = xfer->release(lo);
931 lo->lo_encryption = NULL;
932 module_put(xfer->owner);
938 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
939 const struct loop_info64 *i)
944 struct module *owner = xfer->owner;
946 if (!try_module_get(owner))
949 err = xfer->init(lo, i);
953 lo->lo_encryption = xfer;
958 static int loop_clr_fd(struct loop_device *lo)
960 struct file *filp = lo->lo_backing_file;
961 gfp_t gfp = lo->old_gfp_mask;
962 struct block_device *bdev = lo->lo_device;
964 if (lo->lo_state != Lo_bound)
967 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
973 spin_lock_irq(&lo->lo_lock);
974 lo->lo_state = Lo_rundown;
975 spin_unlock_irq(&lo->lo_lock);
977 kthread_stop(lo->lo_thread);
979 spin_lock_irq(&lo->lo_lock);
980 lo->lo_backing_file = NULL;
981 spin_unlock_irq(&lo->lo_lock);
983 loop_release_xfer(lo);
986 lo->lo_device = NULL;
987 lo->lo_encryption = NULL;
989 lo->lo_sizelimit = 0;
990 lo->lo_encrypt_key_size = 0;
991 lo->lo_thread = NULL;
992 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
993 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
994 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
996 invalidate_bdev(bdev);
997 set_capacity(lo->lo_disk, 0);
1000 bd_set_size(bdev, 0);
1001 /* let user-space know about this change */
1002 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1004 mapping_set_gfp_mask(filp->f_mapping, gfp);
1005 lo->lo_state = Lo_unbound;
1006 /* This is safe: open() is still holding a reference. */
1007 module_put(THIS_MODULE);
1008 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1009 ioctl_by_bdev(bdev, BLKRRPART, 0);
1012 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1013 mutex_unlock(&lo->lo_ctl_mutex);
1015 * Need not hold lo_ctl_mutex to fput backing file.
1016 * Calling fput holding lo_ctl_mutex triggers a circular
1017 * lock dependency possibility warning as fput can take
1018 * bd_mutex which is usually taken before lo_ctl_mutex.
1025 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1028 struct loop_func_table *xfer;
1029 uid_t uid = current_uid();
1031 if (lo->lo_encrypt_key_size &&
1032 lo->lo_key_owner != uid &&
1033 !capable(CAP_SYS_ADMIN))
1035 if (lo->lo_state != Lo_bound)
1037 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1040 err = loop_release_xfer(lo);
1044 if (info->lo_encrypt_type) {
1045 unsigned int type = info->lo_encrypt_type;
1047 if (type >= MAX_LO_CRYPT)
1049 xfer = xfer_funcs[type];
1055 err = loop_init_xfer(lo, xfer, info);
1059 if (lo->lo_offset != info->lo_offset ||
1060 lo->lo_sizelimit != info->lo_sizelimit) {
1061 lo->lo_offset = info->lo_offset;
1062 lo->lo_sizelimit = info->lo_sizelimit;
1063 if (figure_loop_size(lo))
1066 loop_config_discard(lo);
1068 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1069 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1070 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1071 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1075 lo->transfer = xfer->transfer;
1076 lo->ioctl = xfer->ioctl;
1078 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1079 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1080 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1082 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1083 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1084 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1085 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1086 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1089 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1090 lo->lo_init[0] = info->lo_init[0];
1091 lo->lo_init[1] = info->lo_init[1];
1092 if (info->lo_encrypt_key_size) {
1093 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1094 info->lo_encrypt_key_size);
1095 lo->lo_key_owner = uid;
1102 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1104 struct file *file = lo->lo_backing_file;
1108 if (lo->lo_state != Lo_bound)
1110 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1113 memset(info, 0, sizeof(*info));
1114 info->lo_number = lo->lo_number;
1115 info->lo_device = huge_encode_dev(stat.dev);
1116 info->lo_inode = stat.ino;
1117 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1118 info->lo_offset = lo->lo_offset;
1119 info->lo_sizelimit = lo->lo_sizelimit;
1120 info->lo_flags = lo->lo_flags;
1121 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1122 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1123 info->lo_encrypt_type =
1124 lo->lo_encryption ? lo->lo_encryption->number : 0;
1125 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1126 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1127 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1128 lo->lo_encrypt_key_size);
1134 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1136 memset(info64, 0, sizeof(*info64));
1137 info64->lo_number = info->lo_number;
1138 info64->lo_device = info->lo_device;
1139 info64->lo_inode = info->lo_inode;
1140 info64->lo_rdevice = info->lo_rdevice;
1141 info64->lo_offset = info->lo_offset;
1142 info64->lo_sizelimit = 0;
1143 info64->lo_encrypt_type = info->lo_encrypt_type;
1144 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1145 info64->lo_flags = info->lo_flags;
1146 info64->lo_init[0] = info->lo_init[0];
1147 info64->lo_init[1] = info->lo_init[1];
1148 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1149 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1151 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1152 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1156 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1158 memset(info, 0, sizeof(*info));
1159 info->lo_number = info64->lo_number;
1160 info->lo_device = info64->lo_device;
1161 info->lo_inode = info64->lo_inode;
1162 info->lo_rdevice = info64->lo_rdevice;
1163 info->lo_offset = info64->lo_offset;
1164 info->lo_encrypt_type = info64->lo_encrypt_type;
1165 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1166 info->lo_flags = info64->lo_flags;
1167 info->lo_init[0] = info64->lo_init[0];
1168 info->lo_init[1] = info64->lo_init[1];
1169 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1170 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1172 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1173 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1175 /* error in case values were truncated */
1176 if (info->lo_device != info64->lo_device ||
1177 info->lo_rdevice != info64->lo_rdevice ||
1178 info->lo_inode != info64->lo_inode ||
1179 info->lo_offset != info64->lo_offset)
1186 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1188 struct loop_info info;
1189 struct loop_info64 info64;
1191 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1193 loop_info64_from_old(&info, &info64);
1194 return loop_set_status(lo, &info64);
1198 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1200 struct loop_info64 info64;
1202 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1204 return loop_set_status(lo, &info64);
1208 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1209 struct loop_info info;
1210 struct loop_info64 info64;
1216 err = loop_get_status(lo, &info64);
1218 err = loop_info64_to_old(&info64, &info);
1219 if (!err && copy_to_user(arg, &info, sizeof(info)))
1226 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1227 struct loop_info64 info64;
1233 err = loop_get_status(lo, &info64);
1234 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1240 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1247 if (unlikely(lo->lo_state != Lo_bound))
1249 err = figure_loop_size(lo);
1252 sec = get_capacity(lo->lo_disk);
1253 /* the width of sector_t may be narrow for bit-shift */
1256 mutex_lock(&bdev->bd_mutex);
1257 bd_set_size(bdev, sz);
1258 /* let user-space know about the new size */
1259 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1260 mutex_unlock(&bdev->bd_mutex);
1266 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1267 unsigned int cmd, unsigned long arg)
1269 struct loop_device *lo = bdev->bd_disk->private_data;
1272 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1275 err = loop_set_fd(lo, mode, bdev, arg);
1277 case LOOP_CHANGE_FD:
1278 err = loop_change_fd(lo, bdev, arg);
1281 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1282 err = loop_clr_fd(lo);
1286 case LOOP_SET_STATUS:
1287 err = loop_set_status_old(lo, (struct loop_info __user *) arg);
1289 case LOOP_GET_STATUS:
1290 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1292 case LOOP_SET_STATUS64:
1293 err = loop_set_status64(lo, (struct loop_info64 __user *) arg);
1295 case LOOP_GET_STATUS64:
1296 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1298 case LOOP_SET_CAPACITY:
1300 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1301 err = loop_set_capacity(lo, bdev);
1304 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1306 mutex_unlock(&lo->lo_ctl_mutex);
1312 #ifdef CONFIG_COMPAT
1313 struct compat_loop_info {
1314 compat_int_t lo_number; /* ioctl r/o */
1315 compat_dev_t lo_device; /* ioctl r/o */
1316 compat_ulong_t lo_inode; /* ioctl r/o */
1317 compat_dev_t lo_rdevice; /* ioctl r/o */
1318 compat_int_t lo_offset;
1319 compat_int_t lo_encrypt_type;
1320 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1321 compat_int_t lo_flags; /* ioctl r/o */
1322 char lo_name[LO_NAME_SIZE];
1323 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1324 compat_ulong_t lo_init[2];
1329 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1330 * - noinlined to reduce stack space usage in main part of driver
1333 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1334 struct loop_info64 *info64)
1336 struct compat_loop_info info;
1338 if (copy_from_user(&info, arg, sizeof(info)))
1341 memset(info64, 0, sizeof(*info64));
1342 info64->lo_number = info.lo_number;
1343 info64->lo_device = info.lo_device;
1344 info64->lo_inode = info.lo_inode;
1345 info64->lo_rdevice = info.lo_rdevice;
1346 info64->lo_offset = info.lo_offset;
1347 info64->lo_sizelimit = 0;
1348 info64->lo_encrypt_type = info.lo_encrypt_type;
1349 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1350 info64->lo_flags = info.lo_flags;
1351 info64->lo_init[0] = info.lo_init[0];
1352 info64->lo_init[1] = info.lo_init[1];
1353 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1354 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1356 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1357 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1362 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1363 * - noinlined to reduce stack space usage in main part of driver
1366 loop_info64_to_compat(const struct loop_info64 *info64,
1367 struct compat_loop_info __user *arg)
1369 struct compat_loop_info info;
1371 memset(&info, 0, sizeof(info));
1372 info.lo_number = info64->lo_number;
1373 info.lo_device = info64->lo_device;
1374 info.lo_inode = info64->lo_inode;
1375 info.lo_rdevice = info64->lo_rdevice;
1376 info.lo_offset = info64->lo_offset;
1377 info.lo_encrypt_type = info64->lo_encrypt_type;
1378 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1379 info.lo_flags = info64->lo_flags;
1380 info.lo_init[0] = info64->lo_init[0];
1381 info.lo_init[1] = info64->lo_init[1];
1382 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1383 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1385 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1386 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1388 /* error in case values were truncated */
1389 if (info.lo_device != info64->lo_device ||
1390 info.lo_rdevice != info64->lo_rdevice ||
1391 info.lo_inode != info64->lo_inode ||
1392 info.lo_offset != info64->lo_offset ||
1393 info.lo_init[0] != info64->lo_init[0] ||
1394 info.lo_init[1] != info64->lo_init[1])
1397 if (copy_to_user(arg, &info, sizeof(info)))
1403 loop_set_status_compat(struct loop_device *lo,
1404 const struct compat_loop_info __user *arg)
1406 struct loop_info64 info64;
1409 ret = loop_info64_from_compat(arg, &info64);
1412 return loop_set_status(lo, &info64);
1416 loop_get_status_compat(struct loop_device *lo,
1417 struct compat_loop_info __user *arg)
1419 struct loop_info64 info64;
1425 err = loop_get_status(lo, &info64);
1427 err = loop_info64_to_compat(&info64, arg);
1431 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1432 unsigned int cmd, unsigned long arg)
1434 struct loop_device *lo = bdev->bd_disk->private_data;
1438 case LOOP_SET_STATUS:
1439 mutex_lock(&lo->lo_ctl_mutex);
1440 err = loop_set_status_compat(
1441 lo, (const struct compat_loop_info __user *) arg);
1442 mutex_unlock(&lo->lo_ctl_mutex);
1444 case LOOP_GET_STATUS:
1445 mutex_lock(&lo->lo_ctl_mutex);
1446 err = loop_get_status_compat(
1447 lo, (struct compat_loop_info __user *) arg);
1448 mutex_unlock(&lo->lo_ctl_mutex);
1450 case LOOP_SET_CAPACITY:
1452 case LOOP_GET_STATUS64:
1453 case LOOP_SET_STATUS64:
1454 arg = (unsigned long) compat_ptr(arg);
1456 case LOOP_CHANGE_FD:
1457 err = lo_ioctl(bdev, mode, cmd, arg);
1467 static int lo_open(struct block_device *bdev, fmode_t mode)
1469 struct loop_device *lo;
1472 mutex_lock(&loop_index_mutex);
1473 lo = bdev->bd_disk->private_data;
1479 mutex_lock(&lo->lo_ctl_mutex);
1481 mutex_unlock(&lo->lo_ctl_mutex);
1483 mutex_unlock(&loop_index_mutex);
1487 static int lo_release(struct gendisk *disk, fmode_t mode)
1489 struct loop_device *lo = disk->private_data;
1492 mutex_lock(&lo->lo_ctl_mutex);
1494 if (--lo->lo_refcnt)
1497 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1499 * In autoclear mode, stop the loop thread
1500 * and remove configuration after last close.
1502 err = loop_clr_fd(lo);
1507 * Otherwise keep thread (if running) and config,
1508 * but flush possible ongoing bios in thread.
1514 mutex_unlock(&lo->lo_ctl_mutex);
1519 static const struct block_device_operations lo_fops = {
1520 .owner = THIS_MODULE,
1522 .release = lo_release,
1524 #ifdef CONFIG_COMPAT
1525 .compat_ioctl = lo_compat_ioctl,
1530 * And now the modules code and kernel interface.
1532 static int max_loop;
1533 module_param(max_loop, int, S_IRUGO);
1534 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1535 module_param(max_part, int, S_IRUGO);
1536 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1537 MODULE_LICENSE("GPL");
1538 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1540 int loop_register_transfer(struct loop_func_table *funcs)
1542 unsigned int n = funcs->number;
1544 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1546 xfer_funcs[n] = funcs;
1550 static int unregister_transfer_cb(int id, void *ptr, void *data)
1552 struct loop_device *lo = ptr;
1553 struct loop_func_table *xfer = data;
1555 mutex_lock(&lo->lo_ctl_mutex);
1556 if (lo->lo_encryption == xfer)
1557 loop_release_xfer(lo);
1558 mutex_unlock(&lo->lo_ctl_mutex);
1562 int loop_unregister_transfer(int number)
1564 unsigned int n = number;
1565 struct loop_func_table *xfer;
1567 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1570 xfer_funcs[n] = NULL;
1571 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1575 EXPORT_SYMBOL(loop_register_transfer);
1576 EXPORT_SYMBOL(loop_unregister_transfer);
1578 static int loop_add(struct loop_device **l, int i)
1580 struct loop_device *lo;
1581 struct gendisk *disk;
1584 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1590 err = idr_pre_get(&loop_index_idr, GFP_KERNEL);
1597 /* create specific i in the index */
1598 err = idr_get_new_above(&loop_index_idr, lo, i, &m);
1599 if (err >= 0 && i != m) {
1600 idr_remove(&loop_index_idr, m);
1603 } else if (i == -1) {
1606 /* get next free nr */
1607 err = idr_get_new(&loop_index_idr, lo, &m);
1616 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1620 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1622 goto out_free_queue;
1625 * Disable partition scanning by default. The in-kernel partition
1626 * scanning can be requested individually per-device during its
1627 * setup. Userspace can always add and remove partitions from all
1628 * devices. The needed partition minors are allocated from the
1629 * extended minor space, the main loop device numbers will continue
1630 * to match the loop minors, regardless of the number of partitions
1633 * If max_part is given, partition scanning is globally enabled for
1634 * all loop devices. The minors for the main loop devices will be
1635 * multiples of max_part.
1637 * Note: Global-for-all-devices, set-only-at-init, read-only module
1638 * parameteters like 'max_loop' and 'max_part' make things needlessly
1639 * complicated, are too static, inflexible and may surprise
1640 * userspace tools. Parameters like this in general should be avoided.
1643 disk->flags |= GENHD_FL_NO_PART_SCAN;
1644 disk->flags |= GENHD_FL_EXT_DEVT;
1645 mutex_init(&lo->lo_ctl_mutex);
1647 lo->lo_thread = NULL;
1648 init_waitqueue_head(&lo->lo_event);
1649 spin_lock_init(&lo->lo_lock);
1650 disk->major = LOOP_MAJOR;
1651 disk->first_minor = i << part_shift;
1652 disk->fops = &lo_fops;
1653 disk->private_data = lo;
1654 disk->queue = lo->lo_queue;
1655 sprintf(disk->disk_name, "loop%d", i);
1658 return lo->lo_number;
1661 blk_cleanup_queue(lo->lo_queue);
1668 static void loop_remove(struct loop_device *lo)
1670 del_gendisk(lo->lo_disk);
1671 blk_cleanup_queue(lo->lo_queue);
1672 put_disk(lo->lo_disk);
1676 static int find_free_cb(int id, void *ptr, void *data)
1678 struct loop_device *lo = ptr;
1679 struct loop_device **l = data;
1681 if (lo->lo_state == Lo_unbound) {
1688 static int loop_lookup(struct loop_device **l, int i)
1690 struct loop_device *lo;
1696 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1699 ret = lo->lo_number;
1704 /* lookup and return a specific i */
1705 lo = idr_find(&loop_index_idr, i);
1708 ret = lo->lo_number;
1714 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1716 struct loop_device *lo;
1717 struct kobject *kobj;
1720 mutex_lock(&loop_index_mutex);
1721 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1723 err = loop_add(&lo, MINOR(dev) >> part_shift);
1725 kobj = ERR_PTR(err);
1727 kobj = get_disk(lo->lo_disk);
1728 mutex_unlock(&loop_index_mutex);
1734 static long loop_control_ioctl(struct file *file, unsigned int cmd,
1737 struct loop_device *lo;
1740 mutex_lock(&loop_index_mutex);
1743 ret = loop_lookup(&lo, parm);
1748 ret = loop_add(&lo, parm);
1750 case LOOP_CTL_REMOVE:
1751 ret = loop_lookup(&lo, parm);
1754 mutex_lock(&lo->lo_ctl_mutex);
1755 if (lo->lo_state != Lo_unbound) {
1757 mutex_unlock(&lo->lo_ctl_mutex);
1760 if (lo->lo_refcnt > 0) {
1762 mutex_unlock(&lo->lo_ctl_mutex);
1765 lo->lo_disk->private_data = NULL;
1766 mutex_unlock(&lo->lo_ctl_mutex);
1767 idr_remove(&loop_index_idr, lo->lo_number);
1770 case LOOP_CTL_GET_FREE:
1771 ret = loop_lookup(&lo, -1);
1774 ret = loop_add(&lo, -1);
1776 mutex_unlock(&loop_index_mutex);
1781 static const struct file_operations loop_ctl_fops = {
1782 .open = nonseekable_open,
1783 .unlocked_ioctl = loop_control_ioctl,
1784 .compat_ioctl = loop_control_ioctl,
1785 .owner = THIS_MODULE,
1786 .llseek = noop_llseek,
1789 static struct miscdevice loop_misc = {
1790 .minor = LOOP_CTRL_MINOR,
1791 .name = "loop-control",
1792 .fops = &loop_ctl_fops,
1795 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1796 MODULE_ALIAS("devname:loop-control");
1798 static int __init loop_init(void)
1801 unsigned long range;
1802 struct loop_device *lo;
1805 err = misc_register(&loop_misc);
1811 part_shift = fls(max_part);
1814 * Adjust max_part according to part_shift as it is exported
1815 * to user space so that user can decide correct minor number
1816 * if [s]he want to create more devices.
1818 * Note that -1 is required because partition 0 is reserved
1819 * for the whole disk.
1821 max_part = (1UL << part_shift) - 1;
1824 if ((1UL << part_shift) > DISK_MAX_PARTS)
1827 if (max_loop > 1UL << (MINORBITS - part_shift))
1831 * If max_loop is specified, create that many devices upfront.
1832 * This also becomes a hard limit. If max_loop is not specified,
1833 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1834 * init time. Loop devices can be requested on-demand with the
1835 * /dev/loop-control interface, or be instantiated by accessing
1836 * a 'dead' device node.
1840 range = max_loop << part_shift;
1842 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1843 range = 1UL << MINORBITS;
1846 if (register_blkdev(LOOP_MAJOR, "loop"))
1849 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1850 THIS_MODULE, loop_probe, NULL, NULL);
1852 /* pre-create number of devices given by config or max_loop */
1853 mutex_lock(&loop_index_mutex);
1854 for (i = 0; i < nr; i++)
1856 mutex_unlock(&loop_index_mutex);
1858 printk(KERN_INFO "loop: module loaded\n");
1862 static int loop_exit_cb(int id, void *ptr, void *data)
1864 struct loop_device *lo = ptr;
1870 static void __exit loop_exit(void)
1872 unsigned long range;
1874 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1876 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1877 idr_remove_all(&loop_index_idr);
1878 idr_destroy(&loop_index_idr);
1880 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1881 unregister_blkdev(LOOP_MAJOR, "loop");
1883 misc_deregister(&loop_misc);
1886 module_init(loop_init);
1887 module_exit(loop_exit);
1890 static int __init max_loop_setup(char *str)
1892 max_loop = simple_strtol(str, NULL, 0);
1896 __setup("max_loop=", max_loop_setup);