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