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)
165 loff_t size, loopsize;
167 /* Compute loopsize in bytes */
168 size = i_size_read(file->f_mapping->host);
169 loopsize = size - offset;
170 /* offset is beyond i_size, wierd but possible */
174 if (sizelimit > 0 && sizelimit < loopsize)
175 loopsize = sizelimit;
177 * Unfortunately, if we want to do I/O on the device,
178 * the number of 512-byte sectors has to fit into a sector_t.
180 return loopsize >> 9;
183 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
185 return get_size(lo->lo_offset, lo->lo_sizelimit, file);
189 figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
191 loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
192 sector_t x = (sector_t)size;
194 if (unlikely((loff_t)x != size))
196 if (lo->lo_offset != offset)
197 lo->lo_offset = offset;
198 if (lo->lo_sizelimit != sizelimit)
199 lo->lo_sizelimit = sizelimit;
200 set_capacity(lo->lo_disk, x);
205 lo_do_transfer(struct loop_device *lo, int cmd,
206 struct page *rpage, unsigned roffs,
207 struct page *lpage, unsigned loffs,
208 int size, sector_t rblock)
210 if (unlikely(!lo->transfer))
213 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
217 * __do_lo_send_write - helper for writing data to a loop device
219 * This helper just factors out common code between do_lo_send_direct_write()
220 * and do_lo_send_write().
222 static int __do_lo_send_write(struct file *file,
223 u8 *buf, const int len, loff_t pos)
226 mm_segment_t old_fs = get_fs();
229 bw = file->f_op->write(file, buf, len, &pos);
231 if (likely(bw == len))
233 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
234 (unsigned long long)pos, len);
241 * do_lo_send_direct_write - helper for writing data to a loop device
243 * This is the fast, non-transforming version that does not need double
246 static int do_lo_send_direct_write(struct loop_device *lo,
247 struct bio_vec *bvec, loff_t pos, struct page *page)
249 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
250 kmap(bvec->bv_page) + bvec->bv_offset,
252 kunmap(bvec->bv_page);
258 * do_lo_send_write - helper for writing data to a loop device
260 * This is the slow, transforming version that needs to double buffer the
261 * data as it cannot do the transformations in place without having direct
262 * access to the destination pages of the backing file.
264 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
265 loff_t pos, struct page *page)
267 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
268 bvec->bv_offset, bvec->bv_len, pos >> 9);
270 return __do_lo_send_write(lo->lo_backing_file,
271 page_address(page), bvec->bv_len,
273 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
274 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
280 static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
282 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
284 struct bio_vec *bvec;
285 struct page *page = NULL;
288 if (lo->transfer != transfer_none) {
289 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
293 do_lo_send = do_lo_send_write;
295 do_lo_send = do_lo_send_direct_write;
298 bio_for_each_segment(bvec, bio, i) {
299 ret = do_lo_send(lo, bvec, pos, page);
311 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
316 struct lo_read_data {
317 struct loop_device *lo;
324 lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
325 struct splice_desc *sd)
327 struct lo_read_data *p = sd->u.data;
328 struct loop_device *lo = p->lo;
329 struct page *page = buf->page;
333 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
339 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
340 printk(KERN_ERR "loop: transfer error block %ld\n",
345 flush_dcache_page(p->page);
354 lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
356 return __splice_from_pipe(pipe, sd, lo_splice_actor);
360 do_lo_receive(struct loop_device *lo,
361 struct bio_vec *bvec, int bsize, loff_t pos)
363 struct lo_read_data cookie;
364 struct splice_desc sd;
369 cookie.page = bvec->bv_page;
370 cookie.offset = bvec->bv_offset;
371 cookie.bsize = bsize;
374 sd.total_len = bvec->bv_len;
379 file = lo->lo_backing_file;
380 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
386 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
388 struct bio_vec *bvec;
392 bio_for_each_segment(bvec, bio, i) {
393 s = do_lo_receive(lo, bvec, bsize, pos);
397 if (s != bvec->bv_len) {
406 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
411 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
413 if (bio_rw(bio) == WRITE) {
414 struct file *file = lo->lo_backing_file;
416 if (bio->bi_rw & REQ_FLUSH) {
417 ret = vfs_fsync(file, 0);
418 if (unlikely(ret && ret != -EINVAL)) {
425 * We use punch hole to reclaim the free space used by the
426 * image a.k.a. discard. However we do not support discard if
427 * encryption is enabled, because it may give an attacker
428 * useful information.
430 if (bio->bi_rw & REQ_DISCARD) {
431 struct file *file = lo->lo_backing_file;
432 int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
434 if ((!file->f_op->fallocate) ||
435 lo->lo_encrypt_key_size) {
439 ret = file->f_op->fallocate(file, mode, pos,
441 if (unlikely(ret && ret != -EINVAL &&
447 ret = lo_send(lo, bio, pos);
449 if ((bio->bi_rw & REQ_FUA) && !ret) {
450 ret = vfs_fsync(file, 0);
451 if (unlikely(ret && ret != -EINVAL))
455 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
462 * Add bio to back of pending list
464 static void loop_add_bio(struct loop_device *lo, struct bio *bio)
467 bio_list_add(&lo->lo_bio_list, bio);
471 * Grab first pending buffer
473 static struct bio *loop_get_bio(struct loop_device *lo)
476 return bio_list_pop(&lo->lo_bio_list);
479 static void loop_make_request(struct request_queue *q, struct bio *old_bio)
481 struct loop_device *lo = q->queuedata;
482 int rw = bio_rw(old_bio);
487 BUG_ON(!lo || (rw != READ && rw != WRITE));
489 spin_lock_irq(&lo->lo_lock);
490 if (lo->lo_state != Lo_bound)
492 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
494 if (lo->lo_bio_count >= q->nr_congestion_on)
495 wait_event_lock_irq(lo->lo_req_wait,
496 lo->lo_bio_count < q->nr_congestion_off,
498 loop_add_bio(lo, old_bio);
499 wake_up(&lo->lo_event);
500 spin_unlock_irq(&lo->lo_lock);
504 spin_unlock_irq(&lo->lo_lock);
505 bio_io_error(old_bio);
508 struct switch_request {
510 struct completion wait;
513 static void do_loop_switch(struct loop_device *, struct switch_request *);
515 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
517 if (unlikely(!bio->bi_bdev)) {
518 do_loop_switch(lo, bio->bi_private);
521 int ret = do_bio_filebacked(lo, bio);
527 * worker thread that handles reads/writes to file backed loop devices,
528 * to avoid blocking in our make_request_fn. it also does loop decrypting
529 * on reads for block backed loop, as that is too heavy to do from
530 * b_end_io context where irqs may be disabled.
532 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
533 * calling kthread_stop(). Therefore once kthread_should_stop() is
534 * true, make_request will not place any more requests. Therefore
535 * once kthread_should_stop() is true and lo_bio is NULL, we are
536 * done with the loop.
538 static int loop_thread(void *data)
540 struct loop_device *lo = data;
543 set_user_nice(current, -20);
545 while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
547 wait_event_interruptible(lo->lo_event,
548 !bio_list_empty(&lo->lo_bio_list) ||
549 kthread_should_stop());
551 if (bio_list_empty(&lo->lo_bio_list))
553 spin_lock_irq(&lo->lo_lock);
554 bio = loop_get_bio(lo);
555 if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
556 wake_up(&lo->lo_req_wait);
557 spin_unlock_irq(&lo->lo_lock);
560 loop_handle_bio(lo, bio);
567 * loop_switch performs the hard work of switching a backing store.
568 * First it needs to flush existing IO, it does this by sending a magic
569 * BIO down the pipe. The completion of this BIO does the actual switch.
571 static int loop_switch(struct loop_device *lo, struct file *file)
573 struct switch_request w;
574 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
577 init_completion(&w.wait);
579 bio->bi_private = &w;
581 loop_make_request(lo->lo_queue, bio);
582 wait_for_completion(&w.wait);
587 * Helper to flush the IOs in loop, but keeping loop thread running
589 static int loop_flush(struct loop_device *lo)
591 /* loop not yet configured, no running thread, nothing to flush */
595 return loop_switch(lo, NULL);
599 * Do the actual switch; called from the BIO completion routine
601 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
603 struct file *file = p->file;
604 struct file *old_file = lo->lo_backing_file;
605 struct address_space *mapping;
607 /* if no new file, only flush of queued bios requested */
611 mapping = file->f_mapping;
612 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
613 lo->lo_backing_file = file;
614 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
615 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
616 lo->old_gfp_mask = mapping_gfp_mask(mapping);
617 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
624 * loop_change_fd switched the backing store of a loopback device to
625 * a new file. This is useful for operating system installers to free up
626 * the original file and in High Availability environments to switch to
627 * an alternative location for the content in case of server meltdown.
628 * This can only work if the loop device is used read-only, and if the
629 * new backing store is the same size and type as the old backing store.
631 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
634 struct file *file, *old_file;
639 if (lo->lo_state != Lo_bound)
642 /* the loop device has to be read-only */
644 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
652 inode = file->f_mapping->host;
653 old_file = lo->lo_backing_file;
657 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
660 /* size of the new backing store needs to be the same */
661 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
665 error = loop_switch(lo, file);
670 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
671 ioctl_by_bdev(bdev, BLKRRPART, 0);
680 static inline int is_loop_device(struct file *file)
682 struct inode *i = file->f_mapping->host;
684 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
687 /* loop sysfs attributes */
689 static ssize_t loop_attr_show(struct device *dev, char *page,
690 ssize_t (*callback)(struct loop_device *, char *))
692 struct gendisk *disk = dev_to_disk(dev);
693 struct loop_device *lo = disk->private_data;
695 return callback(lo, page);
698 #define LOOP_ATTR_RO(_name) \
699 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
700 static ssize_t loop_attr_do_show_##_name(struct device *d, \
701 struct device_attribute *attr, char *b) \
703 return loop_attr_show(d, b, loop_attr_##_name##_show); \
705 static struct device_attribute loop_attr_##_name = \
706 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
708 static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
713 spin_lock_irq(&lo->lo_lock);
714 if (lo->lo_backing_file)
715 p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
716 spin_unlock_irq(&lo->lo_lock);
718 if (IS_ERR_OR_NULL(p))
722 memmove(buf, p, ret);
730 static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
732 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
735 static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
737 return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
740 static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
742 int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
744 return sprintf(buf, "%s\n", autoclear ? "1" : "0");
747 static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
749 int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
751 return sprintf(buf, "%s\n", partscan ? "1" : "0");
754 LOOP_ATTR_RO(backing_file);
755 LOOP_ATTR_RO(offset);
756 LOOP_ATTR_RO(sizelimit);
757 LOOP_ATTR_RO(autoclear);
758 LOOP_ATTR_RO(partscan);
760 static struct attribute *loop_attrs[] = {
761 &loop_attr_backing_file.attr,
762 &loop_attr_offset.attr,
763 &loop_attr_sizelimit.attr,
764 &loop_attr_autoclear.attr,
765 &loop_attr_partscan.attr,
769 static struct attribute_group loop_attribute_group = {
774 static int loop_sysfs_init(struct loop_device *lo)
776 return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
777 &loop_attribute_group);
780 static void loop_sysfs_exit(struct loop_device *lo)
782 sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
783 &loop_attribute_group);
786 static void loop_config_discard(struct loop_device *lo)
788 struct file *file = lo->lo_backing_file;
789 struct inode *inode = file->f_mapping->host;
790 struct request_queue *q = lo->lo_queue;
793 * We use punch hole to reclaim the free space used by the
794 * image a.k.a. discard. However we do support discard if
795 * encryption is enabled, because it may give an attacker
796 * useful information.
798 if ((!file->f_op->fallocate) ||
799 lo->lo_encrypt_key_size) {
800 q->limits.discard_granularity = 0;
801 q->limits.discard_alignment = 0;
802 q->limits.max_discard_sectors = 0;
803 q->limits.discard_zeroes_data = 0;
804 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
808 q->limits.discard_granularity = inode->i_sb->s_blocksize;
809 q->limits.discard_alignment = 0;
810 q->limits.max_discard_sectors = UINT_MAX >> 9;
811 q->limits.discard_zeroes_data = 1;
812 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
815 static int loop_set_fd(struct loop_device *lo, fmode_t mode,
816 struct block_device *bdev, unsigned int arg)
818 struct file *file, *f;
820 struct address_space *mapping;
821 unsigned lo_blocksize;
826 /* This is safe, since we have a reference from open(). */
827 __module_get(THIS_MODULE);
835 if (lo->lo_state != Lo_unbound)
838 /* Avoid recursion */
840 while (is_loop_device(f)) {
841 struct loop_device *l;
843 if (f->f_mapping->host->i_bdev == bdev)
846 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
847 if (l->lo_state == Lo_unbound) {
851 f = l->lo_backing_file;
854 mapping = file->f_mapping;
855 inode = mapping->host;
858 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
861 if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
863 lo_flags |= LO_FLAGS_READ_ONLY;
865 lo_blocksize = S_ISBLK(inode->i_mode) ?
866 inode->i_bdev->bd_block_size : PAGE_SIZE;
869 size = get_loop_size(lo, file);
870 if ((loff_t)(sector_t)size != size)
875 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
877 lo->lo_blocksize = lo_blocksize;
878 lo->lo_device = bdev;
879 lo->lo_flags = lo_flags;
880 lo->lo_backing_file = file;
881 lo->transfer = transfer_none;
883 lo->lo_sizelimit = 0;
884 lo->lo_bio_count = 0;
885 lo->old_gfp_mask = mapping_gfp_mask(mapping);
886 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
888 bio_list_init(&lo->lo_bio_list);
891 * set queue make_request_fn, and add limits based on lower level
894 blk_queue_make_request(lo->lo_queue, loop_make_request);
895 lo->lo_queue->queuedata = lo;
897 if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
898 blk_queue_flush(lo->lo_queue, REQ_FLUSH);
900 set_capacity(lo->lo_disk, size);
901 bd_set_size(bdev, size << 9);
903 /* let user-space know about the new size */
904 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
906 set_blocksize(bdev, lo_blocksize);
908 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
910 if (IS_ERR(lo->lo_thread)) {
911 error = PTR_ERR(lo->lo_thread);
914 lo->lo_state = Lo_bound;
915 wake_up_process(lo->lo_thread);
917 lo->lo_flags |= LO_FLAGS_PARTSCAN;
918 if (lo->lo_flags & LO_FLAGS_PARTSCAN)
919 ioctl_by_bdev(bdev, BLKRRPART, 0);
924 lo->lo_thread = NULL;
925 lo->lo_device = NULL;
926 lo->lo_backing_file = NULL;
928 set_capacity(lo->lo_disk, 0);
929 invalidate_bdev(bdev);
930 bd_set_size(bdev, 0);
931 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
932 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
933 lo->lo_state = Lo_unbound;
937 /* This is safe: open() is still holding a reference. */
938 module_put(THIS_MODULE);
943 loop_release_xfer(struct loop_device *lo)
946 struct loop_func_table *xfer = lo->lo_encryption;
950 err = xfer->release(lo);
952 lo->lo_encryption = NULL;
953 module_put(xfer->owner);
959 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
960 const struct loop_info64 *i)
965 struct module *owner = xfer->owner;
967 if (!try_module_get(owner))
970 err = xfer->init(lo, i);
974 lo->lo_encryption = xfer;
979 static int loop_clr_fd(struct loop_device *lo)
981 struct file *filp = lo->lo_backing_file;
982 gfp_t gfp = lo->old_gfp_mask;
983 struct block_device *bdev = lo->lo_device;
985 if (lo->lo_state != Lo_bound)
989 * If we've explicitly asked to tear down the loop device,
990 * and it has an elevated reference count, set it for auto-teardown when
991 * the last reference goes away. This stops $!~#$@ udev from
992 * preventing teardown because it decided that it needs to run blkid on
993 * the loopback device whenever they appear. xfstests is notorious for
994 * failing tests because blkid via udev races with a losetup
995 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
996 * command to fail with EBUSY.
998 if (lo->lo_refcnt > 1) {
999 lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
1000 mutex_unlock(&lo->lo_ctl_mutex);
1007 spin_lock_irq(&lo->lo_lock);
1008 lo->lo_state = Lo_rundown;
1009 spin_unlock_irq(&lo->lo_lock);
1011 kthread_stop(lo->lo_thread);
1013 spin_lock_irq(&lo->lo_lock);
1014 lo->lo_backing_file = NULL;
1015 spin_unlock_irq(&lo->lo_lock);
1017 loop_release_xfer(lo);
1018 lo->transfer = NULL;
1020 lo->lo_device = NULL;
1021 lo->lo_encryption = NULL;
1023 lo->lo_sizelimit = 0;
1024 lo->lo_encrypt_key_size = 0;
1025 lo->lo_thread = NULL;
1026 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1027 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1028 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1030 invalidate_bdev(bdev);
1031 set_capacity(lo->lo_disk, 0);
1032 loop_sysfs_exit(lo);
1034 bd_set_size(bdev, 0);
1035 /* let user-space know about this change */
1036 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1038 mapping_set_gfp_mask(filp->f_mapping, gfp);
1039 lo->lo_state = Lo_unbound;
1040 /* This is safe: open() is still holding a reference. */
1041 module_put(THIS_MODULE);
1042 if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1043 ioctl_by_bdev(bdev, BLKRRPART, 0);
1046 lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1047 mutex_unlock(&lo->lo_ctl_mutex);
1049 * Need not hold lo_ctl_mutex to fput backing file.
1050 * Calling fput holding lo_ctl_mutex triggers a circular
1051 * lock dependency possibility warning as fput can take
1052 * bd_mutex which is usually taken before lo_ctl_mutex.
1059 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1062 struct loop_func_table *xfer;
1063 kuid_t uid = current_uid();
1065 if (lo->lo_encrypt_key_size &&
1066 !uid_eq(lo->lo_key_owner, uid) &&
1067 !capable(CAP_SYS_ADMIN))
1069 if (lo->lo_state != Lo_bound)
1071 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1074 err = loop_release_xfer(lo);
1078 if (info->lo_encrypt_type) {
1079 unsigned int type = info->lo_encrypt_type;
1081 if (type >= MAX_LO_CRYPT)
1083 xfer = xfer_funcs[type];
1089 err = loop_init_xfer(lo, xfer, info);
1093 if (lo->lo_offset != info->lo_offset ||
1094 lo->lo_sizelimit != info->lo_sizelimit) {
1095 if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1098 loop_config_discard(lo);
1100 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1101 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1102 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1103 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1107 lo->transfer = xfer->transfer;
1108 lo->ioctl = xfer->ioctl;
1110 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1111 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1112 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1114 if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1115 !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1116 lo->lo_flags |= LO_FLAGS_PARTSCAN;
1117 lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1118 ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1121 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1122 lo->lo_init[0] = info->lo_init[0];
1123 lo->lo_init[1] = info->lo_init[1];
1124 if (info->lo_encrypt_key_size) {
1125 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1126 info->lo_encrypt_key_size);
1127 lo->lo_key_owner = uid;
1134 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1136 struct file *file = lo->lo_backing_file;
1140 if (lo->lo_state != Lo_bound)
1142 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1145 memset(info, 0, sizeof(*info));
1146 info->lo_number = lo->lo_number;
1147 info->lo_device = huge_encode_dev(stat.dev);
1148 info->lo_inode = stat.ino;
1149 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1150 info->lo_offset = lo->lo_offset;
1151 info->lo_sizelimit = lo->lo_sizelimit;
1152 info->lo_flags = lo->lo_flags;
1153 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1154 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1155 info->lo_encrypt_type =
1156 lo->lo_encryption ? lo->lo_encryption->number : 0;
1157 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1158 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1159 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1160 lo->lo_encrypt_key_size);
1166 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1168 memset(info64, 0, sizeof(*info64));
1169 info64->lo_number = info->lo_number;
1170 info64->lo_device = info->lo_device;
1171 info64->lo_inode = info->lo_inode;
1172 info64->lo_rdevice = info->lo_rdevice;
1173 info64->lo_offset = info->lo_offset;
1174 info64->lo_sizelimit = 0;
1175 info64->lo_encrypt_type = info->lo_encrypt_type;
1176 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1177 info64->lo_flags = info->lo_flags;
1178 info64->lo_init[0] = info->lo_init[0];
1179 info64->lo_init[1] = info->lo_init[1];
1180 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1181 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1183 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1184 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1188 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1190 memset(info, 0, sizeof(*info));
1191 info->lo_number = info64->lo_number;
1192 info->lo_device = info64->lo_device;
1193 info->lo_inode = info64->lo_inode;
1194 info->lo_rdevice = info64->lo_rdevice;
1195 info->lo_offset = info64->lo_offset;
1196 info->lo_encrypt_type = info64->lo_encrypt_type;
1197 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1198 info->lo_flags = info64->lo_flags;
1199 info->lo_init[0] = info64->lo_init[0];
1200 info->lo_init[1] = info64->lo_init[1];
1201 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1202 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1204 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1205 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1207 /* error in case values were truncated */
1208 if (info->lo_device != info64->lo_device ||
1209 info->lo_rdevice != info64->lo_rdevice ||
1210 info->lo_inode != info64->lo_inode ||
1211 info->lo_offset != info64->lo_offset)
1218 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1220 struct loop_info info;
1221 struct loop_info64 info64;
1223 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1225 loop_info64_from_old(&info, &info64);
1226 return loop_set_status(lo, &info64);
1230 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1232 struct loop_info64 info64;
1234 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1236 return loop_set_status(lo, &info64);
1240 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1241 struct loop_info info;
1242 struct loop_info64 info64;
1248 err = loop_get_status(lo, &info64);
1250 err = loop_info64_to_old(&info64, &info);
1251 if (!err && copy_to_user(arg, &info, sizeof(info)))
1258 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1259 struct loop_info64 info64;
1265 err = loop_get_status(lo, &info64);
1266 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1272 static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1279 if (unlikely(lo->lo_state != Lo_bound))
1281 err = figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1284 sec = get_capacity(lo->lo_disk);
1285 /* the width of sector_t may be narrow for bit-shift */
1288 mutex_lock(&bdev->bd_mutex);
1289 bd_set_size(bdev, sz);
1290 /* let user-space know about the new size */
1291 kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1292 mutex_unlock(&bdev->bd_mutex);
1298 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1299 unsigned int cmd, unsigned long arg)
1301 struct loop_device *lo = bdev->bd_disk->private_data;
1304 mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1307 err = loop_set_fd(lo, mode, bdev, arg);
1309 case LOOP_CHANGE_FD:
1310 err = loop_change_fd(lo, bdev, arg);
1313 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1314 err = loop_clr_fd(lo);
1318 case LOOP_SET_STATUS:
1320 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1321 err = loop_set_status_old(lo,
1322 (struct loop_info __user *)arg);
1324 case LOOP_GET_STATUS:
1325 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1327 case LOOP_SET_STATUS64:
1329 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1330 err = loop_set_status64(lo,
1331 (struct loop_info64 __user *) arg);
1333 case LOOP_GET_STATUS64:
1334 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1336 case LOOP_SET_CAPACITY:
1338 if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1339 err = loop_set_capacity(lo, bdev);
1342 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1344 mutex_unlock(&lo->lo_ctl_mutex);
1350 #ifdef CONFIG_COMPAT
1351 struct compat_loop_info {
1352 compat_int_t lo_number; /* ioctl r/o */
1353 compat_dev_t lo_device; /* ioctl r/o */
1354 compat_ulong_t lo_inode; /* ioctl r/o */
1355 compat_dev_t lo_rdevice; /* ioctl r/o */
1356 compat_int_t lo_offset;
1357 compat_int_t lo_encrypt_type;
1358 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1359 compat_int_t lo_flags; /* ioctl r/o */
1360 char lo_name[LO_NAME_SIZE];
1361 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1362 compat_ulong_t lo_init[2];
1367 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1368 * - noinlined to reduce stack space usage in main part of driver
1371 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1372 struct loop_info64 *info64)
1374 struct compat_loop_info info;
1376 if (copy_from_user(&info, arg, sizeof(info)))
1379 memset(info64, 0, sizeof(*info64));
1380 info64->lo_number = info.lo_number;
1381 info64->lo_device = info.lo_device;
1382 info64->lo_inode = info.lo_inode;
1383 info64->lo_rdevice = info.lo_rdevice;
1384 info64->lo_offset = info.lo_offset;
1385 info64->lo_sizelimit = 0;
1386 info64->lo_encrypt_type = info.lo_encrypt_type;
1387 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1388 info64->lo_flags = info.lo_flags;
1389 info64->lo_init[0] = info.lo_init[0];
1390 info64->lo_init[1] = info.lo_init[1];
1391 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1392 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1394 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1395 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1400 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1401 * - noinlined to reduce stack space usage in main part of driver
1404 loop_info64_to_compat(const struct loop_info64 *info64,
1405 struct compat_loop_info __user *arg)
1407 struct compat_loop_info info;
1409 memset(&info, 0, sizeof(info));
1410 info.lo_number = info64->lo_number;
1411 info.lo_device = info64->lo_device;
1412 info.lo_inode = info64->lo_inode;
1413 info.lo_rdevice = info64->lo_rdevice;
1414 info.lo_offset = info64->lo_offset;
1415 info.lo_encrypt_type = info64->lo_encrypt_type;
1416 info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1417 info.lo_flags = info64->lo_flags;
1418 info.lo_init[0] = info64->lo_init[0];
1419 info.lo_init[1] = info64->lo_init[1];
1420 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1421 memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1423 memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1424 memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1426 /* error in case values were truncated */
1427 if (info.lo_device != info64->lo_device ||
1428 info.lo_rdevice != info64->lo_rdevice ||
1429 info.lo_inode != info64->lo_inode ||
1430 info.lo_offset != info64->lo_offset ||
1431 info.lo_init[0] != info64->lo_init[0] ||
1432 info.lo_init[1] != info64->lo_init[1])
1435 if (copy_to_user(arg, &info, sizeof(info)))
1441 loop_set_status_compat(struct loop_device *lo,
1442 const struct compat_loop_info __user *arg)
1444 struct loop_info64 info64;
1447 ret = loop_info64_from_compat(arg, &info64);
1450 return loop_set_status(lo, &info64);
1454 loop_get_status_compat(struct loop_device *lo,
1455 struct compat_loop_info __user *arg)
1457 struct loop_info64 info64;
1463 err = loop_get_status(lo, &info64);
1465 err = loop_info64_to_compat(&info64, arg);
1469 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1470 unsigned int cmd, unsigned long arg)
1472 struct loop_device *lo = bdev->bd_disk->private_data;
1476 case LOOP_SET_STATUS:
1477 mutex_lock(&lo->lo_ctl_mutex);
1478 err = loop_set_status_compat(
1479 lo, (const struct compat_loop_info __user *) arg);
1480 mutex_unlock(&lo->lo_ctl_mutex);
1482 case LOOP_GET_STATUS:
1483 mutex_lock(&lo->lo_ctl_mutex);
1484 err = loop_get_status_compat(
1485 lo, (struct compat_loop_info __user *) arg);
1486 mutex_unlock(&lo->lo_ctl_mutex);
1488 case LOOP_SET_CAPACITY:
1490 case LOOP_GET_STATUS64:
1491 case LOOP_SET_STATUS64:
1492 arg = (unsigned long) compat_ptr(arg);
1494 case LOOP_CHANGE_FD:
1495 err = lo_ioctl(bdev, mode, cmd, arg);
1505 static int lo_open(struct block_device *bdev, fmode_t mode)
1507 struct loop_device *lo;
1510 mutex_lock(&loop_index_mutex);
1511 lo = bdev->bd_disk->private_data;
1517 mutex_lock(&lo->lo_ctl_mutex);
1519 mutex_unlock(&lo->lo_ctl_mutex);
1521 mutex_unlock(&loop_index_mutex);
1525 static int lo_release(struct gendisk *disk, fmode_t mode)
1527 struct loop_device *lo = disk->private_data;
1530 mutex_lock(&lo->lo_ctl_mutex);
1532 if (--lo->lo_refcnt)
1535 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1537 * In autoclear mode, stop the loop thread
1538 * and remove configuration after last close.
1540 err = loop_clr_fd(lo);
1545 * Otherwise keep thread (if running) and config,
1546 * but flush possible ongoing bios in thread.
1552 mutex_unlock(&lo->lo_ctl_mutex);
1557 static const struct block_device_operations lo_fops = {
1558 .owner = THIS_MODULE,
1560 .release = lo_release,
1562 #ifdef CONFIG_COMPAT
1563 .compat_ioctl = lo_compat_ioctl,
1568 * And now the modules code and kernel interface.
1570 static int max_loop;
1571 module_param(max_loop, int, S_IRUGO);
1572 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1573 module_param(max_part, int, S_IRUGO);
1574 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1575 MODULE_LICENSE("GPL");
1576 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1578 int loop_register_transfer(struct loop_func_table *funcs)
1580 unsigned int n = funcs->number;
1582 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1584 xfer_funcs[n] = funcs;
1588 static int unregister_transfer_cb(int id, void *ptr, void *data)
1590 struct loop_device *lo = ptr;
1591 struct loop_func_table *xfer = data;
1593 mutex_lock(&lo->lo_ctl_mutex);
1594 if (lo->lo_encryption == xfer)
1595 loop_release_xfer(lo);
1596 mutex_unlock(&lo->lo_ctl_mutex);
1600 int loop_unregister_transfer(int number)
1602 unsigned int n = number;
1603 struct loop_func_table *xfer;
1605 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1608 xfer_funcs[n] = NULL;
1609 idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1613 EXPORT_SYMBOL(loop_register_transfer);
1614 EXPORT_SYMBOL(loop_unregister_transfer);
1616 static int loop_add(struct loop_device **l, int i)
1618 struct loop_device *lo;
1619 struct gendisk *disk;
1623 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1627 if (!idr_pre_get(&loop_index_idr, GFP_KERNEL))
1633 /* create specific i in the index */
1634 err = idr_get_new_above(&loop_index_idr, lo, i, &m);
1635 if (err >= 0 && i != m) {
1636 idr_remove(&loop_index_idr, m);
1639 } else if (i == -1) {
1642 /* get next free nr */
1643 err = idr_get_new(&loop_index_idr, lo, &m);
1652 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1656 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1658 goto out_free_queue;
1661 * Disable partition scanning by default. The in-kernel partition
1662 * scanning can be requested individually per-device during its
1663 * setup. Userspace can always add and remove partitions from all
1664 * devices. The needed partition minors are allocated from the
1665 * extended minor space, the main loop device numbers will continue
1666 * to match the loop minors, regardless of the number of partitions
1669 * If max_part is given, partition scanning is globally enabled for
1670 * all loop devices. The minors for the main loop devices will be
1671 * multiples of max_part.
1673 * Note: Global-for-all-devices, set-only-at-init, read-only module
1674 * parameteters like 'max_loop' and 'max_part' make things needlessly
1675 * complicated, are too static, inflexible and may surprise
1676 * userspace tools. Parameters like this in general should be avoided.
1679 disk->flags |= GENHD_FL_NO_PART_SCAN;
1680 disk->flags |= GENHD_FL_EXT_DEVT;
1681 mutex_init(&lo->lo_ctl_mutex);
1683 lo->lo_thread = NULL;
1684 init_waitqueue_head(&lo->lo_event);
1685 init_waitqueue_head(&lo->lo_req_wait);
1686 spin_lock_init(&lo->lo_lock);
1687 disk->major = LOOP_MAJOR;
1688 disk->first_minor = i << part_shift;
1689 disk->fops = &lo_fops;
1690 disk->private_data = lo;
1691 disk->queue = lo->lo_queue;
1692 sprintf(disk->disk_name, "loop%d", i);
1695 return lo->lo_number;
1698 blk_cleanup_queue(lo->lo_queue);
1705 static void loop_remove(struct loop_device *lo)
1707 del_gendisk(lo->lo_disk);
1708 blk_cleanup_queue(lo->lo_queue);
1709 put_disk(lo->lo_disk);
1713 static int find_free_cb(int id, void *ptr, void *data)
1715 struct loop_device *lo = ptr;
1716 struct loop_device **l = data;
1718 if (lo->lo_state == Lo_unbound) {
1725 static int loop_lookup(struct loop_device **l, int i)
1727 struct loop_device *lo;
1733 err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1736 ret = lo->lo_number;
1741 /* lookup and return a specific i */
1742 lo = idr_find(&loop_index_idr, i);
1745 ret = lo->lo_number;
1751 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1753 struct loop_device *lo;
1754 struct kobject *kobj;
1757 mutex_lock(&loop_index_mutex);
1758 err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1760 err = loop_add(&lo, MINOR(dev) >> part_shift);
1762 kobj = ERR_PTR(err);
1764 kobj = get_disk(lo->lo_disk);
1765 mutex_unlock(&loop_index_mutex);
1771 static long loop_control_ioctl(struct file *file, unsigned int cmd,
1774 struct loop_device *lo;
1777 mutex_lock(&loop_index_mutex);
1780 ret = loop_lookup(&lo, parm);
1785 ret = loop_add(&lo, parm);
1787 case LOOP_CTL_REMOVE:
1788 ret = loop_lookup(&lo, parm);
1791 mutex_lock(&lo->lo_ctl_mutex);
1792 if (lo->lo_state != Lo_unbound) {
1794 mutex_unlock(&lo->lo_ctl_mutex);
1797 if (lo->lo_refcnt > 0) {
1799 mutex_unlock(&lo->lo_ctl_mutex);
1802 lo->lo_disk->private_data = NULL;
1803 mutex_unlock(&lo->lo_ctl_mutex);
1804 idr_remove(&loop_index_idr, lo->lo_number);
1807 case LOOP_CTL_GET_FREE:
1808 ret = loop_lookup(&lo, -1);
1811 ret = loop_add(&lo, -1);
1813 mutex_unlock(&loop_index_mutex);
1818 static const struct file_operations loop_ctl_fops = {
1819 .open = nonseekable_open,
1820 .unlocked_ioctl = loop_control_ioctl,
1821 .compat_ioctl = loop_control_ioctl,
1822 .owner = THIS_MODULE,
1823 .llseek = noop_llseek,
1826 static struct miscdevice loop_misc = {
1827 .minor = LOOP_CTRL_MINOR,
1828 .name = "loop-control",
1829 .fops = &loop_ctl_fops,
1832 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1833 MODULE_ALIAS("devname:loop-control");
1835 static int __init loop_init(void)
1838 unsigned long range;
1839 struct loop_device *lo;
1842 err = misc_register(&loop_misc);
1848 part_shift = fls(max_part);
1851 * Adjust max_part according to part_shift as it is exported
1852 * to user space so that user can decide correct minor number
1853 * if [s]he want to create more devices.
1855 * Note that -1 is required because partition 0 is reserved
1856 * for the whole disk.
1858 max_part = (1UL << part_shift) - 1;
1861 if ((1UL << part_shift) > DISK_MAX_PARTS)
1864 if (max_loop > 1UL << (MINORBITS - part_shift))
1868 * If max_loop is specified, create that many devices upfront.
1869 * This also becomes a hard limit. If max_loop is not specified,
1870 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1871 * init time. Loop devices can be requested on-demand with the
1872 * /dev/loop-control interface, or be instantiated by accessing
1873 * a 'dead' device node.
1877 range = max_loop << part_shift;
1879 nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1880 range = 1UL << MINORBITS;
1883 if (register_blkdev(LOOP_MAJOR, "loop"))
1886 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1887 THIS_MODULE, loop_probe, NULL, NULL);
1889 /* pre-create number of devices given by config or max_loop */
1890 mutex_lock(&loop_index_mutex);
1891 for (i = 0; i < nr; i++)
1893 mutex_unlock(&loop_index_mutex);
1895 printk(KERN_INFO "loop: module loaded\n");
1899 static int loop_exit_cb(int id, void *ptr, void *data)
1901 struct loop_device *lo = ptr;
1907 static void __exit loop_exit(void)
1909 unsigned long range;
1911 range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1913 idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1914 idr_remove_all(&loop_index_idr);
1915 idr_destroy(&loop_index_idr);
1917 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1918 unregister_blkdev(LOOP_MAJOR, "loop");
1920 misc_deregister(&loop_misc);
1923 module_init(loop_init);
1924 module_exit(loop_exit);
1927 static int __init max_loop_setup(char *str)
1929 max_loop = simple_strtol(str, NULL, 0);
1933 __setup("max_loop=", max_loop_setup);