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 struct workqueue_struct
*loop_wq
;
91 static int transfer_xor(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
;
109 key
= lo
->lo_encrypt_key
;
110 keysize
= lo
->lo_encrypt_key_size
;
111 for (i
= 0; i
< size
; i
++)
112 *out
++ = *in
++ ^ key
[(i
& 511) % keysize
];
114 kunmap_atomic(loop_buf
);
115 kunmap_atomic(raw_buf
);
120 static int xor_init(struct loop_device
*lo
, const struct loop_info64
*info
)
122 if (unlikely(info
->lo_encrypt_key_size
<= 0))
127 static struct loop_func_table none_funcs
= {
128 .number
= LO_CRYPT_NONE
,
131 static struct loop_func_table xor_funcs
= {
132 .number
= LO_CRYPT_XOR
,
133 .transfer
= transfer_xor
,
137 /* xfer_funcs[0] is special - its release function is never called */
138 static struct loop_func_table
*xfer_funcs
[MAX_LO_CRYPT
] = {
143 static loff_t
get_size(loff_t offset
, loff_t sizelimit
, struct file
*file
)
147 /* Compute loopsize in bytes */
148 loopsize
= i_size_read(file
->f_mapping
->host
);
151 /* offset is beyond i_size, weird but possible */
155 if (sizelimit
> 0 && sizelimit
< loopsize
)
156 loopsize
= sizelimit
;
158 * Unfortunately, if we want to do I/O on the device,
159 * the number of 512-byte sectors has to fit into a sector_t.
161 return loopsize
>> 9;
164 static loff_t
get_loop_size(struct loop_device
*lo
, struct file
*file
)
166 return get_size(lo
->lo_offset
, lo
->lo_sizelimit
, file
);
170 figure_loop_size(struct loop_device
*lo
, loff_t offset
, loff_t sizelimit
)
172 loff_t size
= get_size(offset
, sizelimit
, lo
->lo_backing_file
);
173 sector_t x
= (sector_t
)size
;
174 struct block_device
*bdev
= lo
->lo_device
;
176 if (unlikely((loff_t
)x
!= size
))
178 if (lo
->lo_offset
!= offset
)
179 lo
->lo_offset
= offset
;
180 if (lo
->lo_sizelimit
!= sizelimit
)
181 lo
->lo_sizelimit
= sizelimit
;
182 set_capacity(lo
->lo_disk
, x
);
183 bd_set_size(bdev
, (loff_t
)get_capacity(bdev
->bd_disk
) << 9);
184 /* let user-space know about the new size */
185 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
190 lo_do_transfer(struct loop_device
*lo
, int cmd
,
191 struct page
*rpage
, unsigned roffs
,
192 struct page
*lpage
, unsigned loffs
,
193 int size
, sector_t rblock
)
197 ret
= lo
->transfer(lo
, cmd
, rpage
, roffs
, lpage
, loffs
, size
, rblock
);
201 printk_ratelimited(KERN_ERR
202 "loop: Transfer error at byte offset %llu, length %i.\n",
203 (unsigned long long)rblock
<< 9, size
);
207 static int lo_write_bvec(struct file
*file
, struct bio_vec
*bvec
, loff_t
*ppos
)
212 iov_iter_bvec(&i
, ITER_BVEC
, bvec
, 1, bvec
->bv_len
);
214 file_start_write(file
);
215 bw
= vfs_iter_write(file
, &i
, ppos
);
216 file_end_write(file
);
218 if (likely(bw
== bvec
->bv_len
))
221 printk_ratelimited(KERN_ERR
222 "loop: Write error at byte offset %llu, length %i.\n",
223 (unsigned long long)*ppos
, bvec
->bv_len
);
229 static int lo_write_simple(struct loop_device
*lo
, struct request
*rq
,
233 struct req_iterator iter
;
236 rq_for_each_segment(bvec
, rq
, iter
) {
237 ret
= lo_write_bvec(lo
->lo_backing_file
, &bvec
, &pos
);
247 * This is the slow, transforming version that needs to double buffer the
248 * data as it cannot do the transformations in place without having direct
249 * access to the destination pages of the backing file.
251 static int lo_write_transfer(struct loop_device
*lo
, struct request
*rq
,
254 struct bio_vec bvec
, b
;
255 struct req_iterator iter
;
259 page
= alloc_page(GFP_NOIO
);
263 rq_for_each_segment(bvec
, rq
, iter
) {
264 ret
= lo_do_transfer(lo
, WRITE
, page
, 0, bvec
.bv_page
,
265 bvec
.bv_offset
, bvec
.bv_len
, pos
>> 9);
271 b
.bv_len
= bvec
.bv_len
;
272 ret
= lo_write_bvec(lo
->lo_backing_file
, &b
, &pos
);
281 static int lo_read_simple(struct loop_device
*lo
, struct request
*rq
,
285 struct req_iterator iter
;
289 rq_for_each_segment(bvec
, rq
, iter
) {
290 iov_iter_bvec(&i
, ITER_BVEC
, &bvec
, 1, bvec
.bv_len
);
291 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
295 flush_dcache_page(bvec
.bv_page
);
297 if (len
!= bvec
.bv_len
) {
300 __rq_for_each_bio(bio
, rq
)
310 static int lo_read_transfer(struct loop_device
*lo
, struct request
*rq
,
313 struct bio_vec bvec
, b
;
314 struct req_iterator iter
;
320 page
= alloc_page(GFP_NOIO
);
324 rq_for_each_segment(bvec
, rq
, iter
) {
329 b
.bv_len
= bvec
.bv_len
;
331 iov_iter_bvec(&i
, ITER_BVEC
, &b
, 1, b
.bv_len
);
332 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
338 ret
= lo_do_transfer(lo
, READ
, page
, 0, bvec
.bv_page
,
339 bvec
.bv_offset
, len
, offset
>> 9);
343 flush_dcache_page(bvec
.bv_page
);
345 if (len
!= bvec
.bv_len
) {
348 __rq_for_each_bio(bio
, rq
)
360 static int lo_discard(struct loop_device
*lo
, struct request
*rq
, loff_t pos
)
363 * We use punch hole to reclaim the free space used by the
364 * image a.k.a. discard. However we do not support discard if
365 * encryption is enabled, because it may give an attacker
366 * useful information.
368 struct file
*file
= lo
->lo_backing_file
;
369 int mode
= FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
;
372 if ((!file
->f_op
->fallocate
) || lo
->lo_encrypt_key_size
) {
377 ret
= file
->f_op
->fallocate(file
, mode
, pos
, blk_rq_bytes(rq
));
378 if (unlikely(ret
&& ret
!= -EINVAL
&& ret
!= -EOPNOTSUPP
))
384 static int lo_req_flush(struct loop_device
*lo
, struct request
*rq
)
386 struct file
*file
= lo
->lo_backing_file
;
387 int ret
= vfs_fsync(file
, 0);
388 if (unlikely(ret
&& ret
!= -EINVAL
))
394 static int do_req_filebacked(struct loop_device
*lo
, struct request
*rq
)
399 pos
= ((loff_t
) blk_rq_pos(rq
) << 9) + lo
->lo_offset
;
401 if (rq
->cmd_flags
& REQ_WRITE
) {
402 if (rq
->cmd_flags
& REQ_FLUSH
)
403 ret
= lo_req_flush(lo
, rq
);
404 else if (rq
->cmd_flags
& REQ_DISCARD
)
405 ret
= lo_discard(lo
, rq
, pos
);
406 else if (lo
->transfer
)
407 ret
= lo_write_transfer(lo
, rq
, pos
);
409 ret
= lo_write_simple(lo
, rq
, pos
);
413 ret
= lo_read_transfer(lo
, rq
, pos
);
415 ret
= lo_read_simple(lo
, rq
, pos
);
421 struct switch_request
{
423 struct completion wait
;
427 * Do the actual switch; called from the BIO completion routine
429 static void do_loop_switch(struct loop_device
*lo
, struct switch_request
*p
)
431 struct file
*file
= p
->file
;
432 struct file
*old_file
= lo
->lo_backing_file
;
433 struct address_space
*mapping
;
435 /* if no new file, only flush of queued bios requested */
439 mapping
= file
->f_mapping
;
440 mapping_set_gfp_mask(old_file
->f_mapping
, lo
->old_gfp_mask
);
441 lo
->lo_backing_file
= file
;
442 lo
->lo_blocksize
= S_ISBLK(mapping
->host
->i_mode
) ?
443 mapping
->host
->i_bdev
->bd_block_size
: PAGE_SIZE
;
444 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
445 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
449 * loop_switch performs the hard work of switching a backing store.
450 * First it needs to flush existing IO, it does this by sending a magic
451 * BIO down the pipe. The completion of this BIO does the actual switch.
453 static int loop_switch(struct loop_device
*lo
, struct file
*file
)
455 struct switch_request w
;
459 /* freeze queue and wait for completion of scheduled requests */
460 blk_mq_freeze_queue(lo
->lo_queue
);
462 /* do the switch action */
463 do_loop_switch(lo
, &w
);
466 blk_mq_unfreeze_queue(lo
->lo_queue
);
472 * Helper to flush the IOs in loop, but keeping loop thread running
474 static int loop_flush(struct loop_device
*lo
)
476 return loop_switch(lo
, NULL
);
480 * loop_change_fd switched the backing store of a loopback device to
481 * a new file. This is useful for operating system installers to free up
482 * the original file and in High Availability environments to switch to
483 * an alternative location for the content in case of server meltdown.
484 * This can only work if the loop device is used read-only, and if the
485 * new backing store is the same size and type as the old backing store.
487 static int loop_change_fd(struct loop_device
*lo
, struct block_device
*bdev
,
490 struct file
*file
, *old_file
;
495 if (lo
->lo_state
!= Lo_bound
)
498 /* the loop device has to be read-only */
500 if (!(lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
508 inode
= file
->f_mapping
->host
;
509 old_file
= lo
->lo_backing_file
;
513 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
516 /* size of the new backing store needs to be the same */
517 if (get_loop_size(lo
, file
) != get_loop_size(lo
, old_file
))
521 error
= loop_switch(lo
, file
);
526 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
527 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
536 static inline int is_loop_device(struct file
*file
)
538 struct inode
*i
= file
->f_mapping
->host
;
540 return i
&& S_ISBLK(i
->i_mode
) && MAJOR(i
->i_rdev
) == LOOP_MAJOR
;
543 /* loop sysfs attributes */
545 static ssize_t
loop_attr_show(struct device
*dev
, char *page
,
546 ssize_t (*callback
)(struct loop_device
*, char *))
548 struct gendisk
*disk
= dev_to_disk(dev
);
549 struct loop_device
*lo
= disk
->private_data
;
551 return callback(lo
, page
);
554 #define LOOP_ATTR_RO(_name) \
555 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
556 static ssize_t loop_attr_do_show_##_name(struct device *d, \
557 struct device_attribute *attr, char *b) \
559 return loop_attr_show(d, b, loop_attr_##_name##_show); \
561 static struct device_attribute loop_attr_##_name = \
562 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
564 static ssize_t
loop_attr_backing_file_show(struct loop_device
*lo
, char *buf
)
569 spin_lock_irq(&lo
->lo_lock
);
570 if (lo
->lo_backing_file
)
571 p
= d_path(&lo
->lo_backing_file
->f_path
, buf
, PAGE_SIZE
- 1);
572 spin_unlock_irq(&lo
->lo_lock
);
574 if (IS_ERR_OR_NULL(p
))
578 memmove(buf
, p
, ret
);
586 static ssize_t
loop_attr_offset_show(struct loop_device
*lo
, char *buf
)
588 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_offset
);
591 static ssize_t
loop_attr_sizelimit_show(struct loop_device
*lo
, char *buf
)
593 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_sizelimit
);
596 static ssize_t
loop_attr_autoclear_show(struct loop_device
*lo
, char *buf
)
598 int autoclear
= (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
);
600 return sprintf(buf
, "%s\n", autoclear
? "1" : "0");
603 static ssize_t
loop_attr_partscan_show(struct loop_device
*lo
, char *buf
)
605 int partscan
= (lo
->lo_flags
& LO_FLAGS_PARTSCAN
);
607 return sprintf(buf
, "%s\n", partscan
? "1" : "0");
610 LOOP_ATTR_RO(backing_file
);
611 LOOP_ATTR_RO(offset
);
612 LOOP_ATTR_RO(sizelimit
);
613 LOOP_ATTR_RO(autoclear
);
614 LOOP_ATTR_RO(partscan
);
616 static struct attribute
*loop_attrs
[] = {
617 &loop_attr_backing_file
.attr
,
618 &loop_attr_offset
.attr
,
619 &loop_attr_sizelimit
.attr
,
620 &loop_attr_autoclear
.attr
,
621 &loop_attr_partscan
.attr
,
625 static struct attribute_group loop_attribute_group
= {
630 static int loop_sysfs_init(struct loop_device
*lo
)
632 return sysfs_create_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
633 &loop_attribute_group
);
636 static void loop_sysfs_exit(struct loop_device
*lo
)
638 sysfs_remove_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
639 &loop_attribute_group
);
642 static void loop_config_discard(struct loop_device
*lo
)
644 struct file
*file
= lo
->lo_backing_file
;
645 struct inode
*inode
= file
->f_mapping
->host
;
646 struct request_queue
*q
= lo
->lo_queue
;
649 * We use punch hole to reclaim the free space used by the
650 * image a.k.a. discard. However we do not support discard if
651 * encryption is enabled, because it may give an attacker
652 * useful information.
654 if ((!file
->f_op
->fallocate
) ||
655 lo
->lo_encrypt_key_size
) {
656 q
->limits
.discard_granularity
= 0;
657 q
->limits
.discard_alignment
= 0;
658 q
->limits
.max_discard_sectors
= 0;
659 q
->limits
.discard_zeroes_data
= 0;
660 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD
, q
);
664 q
->limits
.discard_granularity
= inode
->i_sb
->s_blocksize
;
665 q
->limits
.discard_alignment
= 0;
666 q
->limits
.max_discard_sectors
= UINT_MAX
>> 9;
667 q
->limits
.discard_zeroes_data
= 1;
668 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, q
);
671 static int loop_set_fd(struct loop_device
*lo
, fmode_t mode
,
672 struct block_device
*bdev
, unsigned int arg
)
674 struct file
*file
, *f
;
676 struct address_space
*mapping
;
677 unsigned lo_blocksize
;
682 /* This is safe, since we have a reference from open(). */
683 __module_get(THIS_MODULE
);
691 if (lo
->lo_state
!= Lo_unbound
)
694 /* Avoid recursion */
696 while (is_loop_device(f
)) {
697 struct loop_device
*l
;
699 if (f
->f_mapping
->host
->i_bdev
== bdev
)
702 l
= f
->f_mapping
->host
->i_bdev
->bd_disk
->private_data
;
703 if (l
->lo_state
== Lo_unbound
) {
707 f
= l
->lo_backing_file
;
710 mapping
= file
->f_mapping
;
711 inode
= mapping
->host
;
714 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
717 if (!(file
->f_mode
& FMODE_WRITE
) || !(mode
& FMODE_WRITE
) ||
718 !file
->f_op
->write_iter
)
719 lo_flags
|= LO_FLAGS_READ_ONLY
;
721 lo_blocksize
= S_ISBLK(inode
->i_mode
) ?
722 inode
->i_bdev
->bd_block_size
: PAGE_SIZE
;
725 size
= get_loop_size(lo
, file
);
726 if ((loff_t
)(sector_t
)size
!= size
)
731 set_device_ro(bdev
, (lo_flags
& LO_FLAGS_READ_ONLY
) != 0);
733 lo
->lo_blocksize
= lo_blocksize
;
734 lo
->lo_device
= bdev
;
735 lo
->lo_flags
= lo_flags
;
736 lo
->lo_backing_file
= file
;
739 lo
->lo_sizelimit
= 0;
740 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
741 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
743 if (!(lo_flags
& LO_FLAGS_READ_ONLY
) && file
->f_op
->fsync
)
744 blk_queue_flush(lo
->lo_queue
, REQ_FLUSH
);
746 set_capacity(lo
->lo_disk
, size
);
747 bd_set_size(bdev
, size
<< 9);
749 /* let user-space know about the new size */
750 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
752 set_blocksize(bdev
, lo_blocksize
);
754 lo
->lo_state
= Lo_bound
;
756 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
757 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
758 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
760 /* Grab the block_device to prevent its destruction after we
761 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
769 /* This is safe: open() is still holding a reference. */
770 module_put(THIS_MODULE
);
775 loop_release_xfer(struct loop_device
*lo
)
778 struct loop_func_table
*xfer
= lo
->lo_encryption
;
782 err
= xfer
->release(lo
);
784 lo
->lo_encryption
= NULL
;
785 module_put(xfer
->owner
);
791 loop_init_xfer(struct loop_device
*lo
, struct loop_func_table
*xfer
,
792 const struct loop_info64
*i
)
797 struct module
*owner
= xfer
->owner
;
799 if (!try_module_get(owner
))
802 err
= xfer
->init(lo
, i
);
806 lo
->lo_encryption
= xfer
;
811 static int loop_clr_fd(struct loop_device
*lo
)
813 struct file
*filp
= lo
->lo_backing_file
;
814 gfp_t gfp
= lo
->old_gfp_mask
;
815 struct block_device
*bdev
= lo
->lo_device
;
817 if (lo
->lo_state
!= Lo_bound
)
821 * If we've explicitly asked to tear down the loop device,
822 * and it has an elevated reference count, set it for auto-teardown when
823 * the last reference goes away. This stops $!~#$@ udev from
824 * preventing teardown because it decided that it needs to run blkid on
825 * the loopback device whenever they appear. xfstests is notorious for
826 * failing tests because blkid via udev races with a losetup
827 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
828 * command to fail with EBUSY.
830 if (lo
->lo_refcnt
> 1) {
831 lo
->lo_flags
|= LO_FLAGS_AUTOCLEAR
;
832 mutex_unlock(&lo
->lo_ctl_mutex
);
839 spin_lock_irq(&lo
->lo_lock
);
840 lo
->lo_state
= Lo_rundown
;
841 lo
->lo_backing_file
= NULL
;
842 spin_unlock_irq(&lo
->lo_lock
);
844 loop_release_xfer(lo
);
847 lo
->lo_device
= NULL
;
848 lo
->lo_encryption
= NULL
;
850 lo
->lo_sizelimit
= 0;
851 lo
->lo_encrypt_key_size
= 0;
852 memset(lo
->lo_encrypt_key
, 0, LO_KEY_SIZE
);
853 memset(lo
->lo_crypt_name
, 0, LO_NAME_SIZE
);
854 memset(lo
->lo_file_name
, 0, LO_NAME_SIZE
);
857 invalidate_bdev(bdev
);
859 set_capacity(lo
->lo_disk
, 0);
862 bd_set_size(bdev
, 0);
863 /* let user-space know about this change */
864 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
866 mapping_set_gfp_mask(filp
->f_mapping
, gfp
);
867 lo
->lo_state
= Lo_unbound
;
868 /* This is safe: open() is still holding a reference. */
869 module_put(THIS_MODULE
);
870 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
&& bdev
)
871 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
874 lo
->lo_disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
875 mutex_unlock(&lo
->lo_ctl_mutex
);
877 * Need not hold lo_ctl_mutex to fput backing file.
878 * Calling fput holding lo_ctl_mutex triggers a circular
879 * lock dependency possibility warning as fput can take
880 * bd_mutex which is usually taken before lo_ctl_mutex.
887 loop_set_status(struct loop_device
*lo
, const struct loop_info64
*info
)
890 struct loop_func_table
*xfer
;
891 kuid_t uid
= current_uid();
893 if (lo
->lo_encrypt_key_size
&&
894 !uid_eq(lo
->lo_key_owner
, uid
) &&
895 !capable(CAP_SYS_ADMIN
))
897 if (lo
->lo_state
!= Lo_bound
)
899 if ((unsigned int) info
->lo_encrypt_key_size
> LO_KEY_SIZE
)
902 err
= loop_release_xfer(lo
);
906 if (info
->lo_encrypt_type
) {
907 unsigned int type
= info
->lo_encrypt_type
;
909 if (type
>= MAX_LO_CRYPT
)
911 xfer
= xfer_funcs
[type
];
917 err
= loop_init_xfer(lo
, xfer
, info
);
921 if (lo
->lo_offset
!= info
->lo_offset
||
922 lo
->lo_sizelimit
!= info
->lo_sizelimit
)
923 if (figure_loop_size(lo
, info
->lo_offset
, info
->lo_sizelimit
))
926 loop_config_discard(lo
);
928 memcpy(lo
->lo_file_name
, info
->lo_file_name
, LO_NAME_SIZE
);
929 memcpy(lo
->lo_crypt_name
, info
->lo_crypt_name
, LO_NAME_SIZE
);
930 lo
->lo_file_name
[LO_NAME_SIZE
-1] = 0;
931 lo
->lo_crypt_name
[LO_NAME_SIZE
-1] = 0;
935 lo
->transfer
= xfer
->transfer
;
936 lo
->ioctl
= xfer
->ioctl
;
938 if ((lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) !=
939 (info
->lo_flags
& LO_FLAGS_AUTOCLEAR
))
940 lo
->lo_flags
^= LO_FLAGS_AUTOCLEAR
;
942 if ((info
->lo_flags
& LO_FLAGS_PARTSCAN
) &&
943 !(lo
->lo_flags
& LO_FLAGS_PARTSCAN
)) {
944 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
945 lo
->lo_disk
->flags
&= ~GENHD_FL_NO_PART_SCAN
;
946 ioctl_by_bdev(lo
->lo_device
, BLKRRPART
, 0);
949 lo
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
950 lo
->lo_init
[0] = info
->lo_init
[0];
951 lo
->lo_init
[1] = info
->lo_init
[1];
952 if (info
->lo_encrypt_key_size
) {
953 memcpy(lo
->lo_encrypt_key
, info
->lo_encrypt_key
,
954 info
->lo_encrypt_key_size
);
955 lo
->lo_key_owner
= uid
;
962 loop_get_status(struct loop_device
*lo
, struct loop_info64
*info
)
964 struct file
*file
= lo
->lo_backing_file
;
968 if (lo
->lo_state
!= Lo_bound
)
970 error
= vfs_getattr(&file
->f_path
, &stat
);
973 memset(info
, 0, sizeof(*info
));
974 info
->lo_number
= lo
->lo_number
;
975 info
->lo_device
= huge_encode_dev(stat
.dev
);
976 info
->lo_inode
= stat
.ino
;
977 info
->lo_rdevice
= huge_encode_dev(lo
->lo_device
? stat
.rdev
: stat
.dev
);
978 info
->lo_offset
= lo
->lo_offset
;
979 info
->lo_sizelimit
= lo
->lo_sizelimit
;
980 info
->lo_flags
= lo
->lo_flags
;
981 memcpy(info
->lo_file_name
, lo
->lo_file_name
, LO_NAME_SIZE
);
982 memcpy(info
->lo_crypt_name
, lo
->lo_crypt_name
, LO_NAME_SIZE
);
983 info
->lo_encrypt_type
=
984 lo
->lo_encryption
? lo
->lo_encryption
->number
: 0;
985 if (lo
->lo_encrypt_key_size
&& capable(CAP_SYS_ADMIN
)) {
986 info
->lo_encrypt_key_size
= lo
->lo_encrypt_key_size
;
987 memcpy(info
->lo_encrypt_key
, lo
->lo_encrypt_key
,
988 lo
->lo_encrypt_key_size
);
994 loop_info64_from_old(const struct loop_info
*info
, struct loop_info64
*info64
)
996 memset(info64
, 0, sizeof(*info64
));
997 info64
->lo_number
= info
->lo_number
;
998 info64
->lo_device
= info
->lo_device
;
999 info64
->lo_inode
= info
->lo_inode
;
1000 info64
->lo_rdevice
= info
->lo_rdevice
;
1001 info64
->lo_offset
= info
->lo_offset
;
1002 info64
->lo_sizelimit
= 0;
1003 info64
->lo_encrypt_type
= info
->lo_encrypt_type
;
1004 info64
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1005 info64
->lo_flags
= info
->lo_flags
;
1006 info64
->lo_init
[0] = info
->lo_init
[0];
1007 info64
->lo_init
[1] = info
->lo_init
[1];
1008 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1009 memcpy(info64
->lo_crypt_name
, info
->lo_name
, LO_NAME_SIZE
);
1011 memcpy(info64
->lo_file_name
, info
->lo_name
, LO_NAME_SIZE
);
1012 memcpy(info64
->lo_encrypt_key
, info
->lo_encrypt_key
, LO_KEY_SIZE
);
1016 loop_info64_to_old(const struct loop_info64
*info64
, struct loop_info
*info
)
1018 memset(info
, 0, sizeof(*info
));
1019 info
->lo_number
= info64
->lo_number
;
1020 info
->lo_device
= info64
->lo_device
;
1021 info
->lo_inode
= info64
->lo_inode
;
1022 info
->lo_rdevice
= info64
->lo_rdevice
;
1023 info
->lo_offset
= info64
->lo_offset
;
1024 info
->lo_encrypt_type
= info64
->lo_encrypt_type
;
1025 info
->lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1026 info
->lo_flags
= info64
->lo_flags
;
1027 info
->lo_init
[0] = info64
->lo_init
[0];
1028 info
->lo_init
[1] = info64
->lo_init
[1];
1029 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1030 memcpy(info
->lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1032 memcpy(info
->lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1033 memcpy(info
->lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1035 /* error in case values were truncated */
1036 if (info
->lo_device
!= info64
->lo_device
||
1037 info
->lo_rdevice
!= info64
->lo_rdevice
||
1038 info
->lo_inode
!= info64
->lo_inode
||
1039 info
->lo_offset
!= info64
->lo_offset
)
1046 loop_set_status_old(struct loop_device
*lo
, const struct loop_info __user
*arg
)
1048 struct loop_info info
;
1049 struct loop_info64 info64
;
1051 if (copy_from_user(&info
, arg
, sizeof (struct loop_info
)))
1053 loop_info64_from_old(&info
, &info64
);
1054 return loop_set_status(lo
, &info64
);
1058 loop_set_status64(struct loop_device
*lo
, const struct loop_info64 __user
*arg
)
1060 struct loop_info64 info64
;
1062 if (copy_from_user(&info64
, arg
, sizeof (struct loop_info64
)))
1064 return loop_set_status(lo
, &info64
);
1068 loop_get_status_old(struct loop_device
*lo
, struct loop_info __user
*arg
) {
1069 struct loop_info info
;
1070 struct loop_info64 info64
;
1076 err
= loop_get_status(lo
, &info64
);
1078 err
= loop_info64_to_old(&info64
, &info
);
1079 if (!err
&& copy_to_user(arg
, &info
, sizeof(info
)))
1086 loop_get_status64(struct loop_device
*lo
, struct loop_info64 __user
*arg
) {
1087 struct loop_info64 info64
;
1093 err
= loop_get_status(lo
, &info64
);
1094 if (!err
&& copy_to_user(arg
, &info64
, sizeof(info64
)))
1100 static int loop_set_capacity(struct loop_device
*lo
, struct block_device
*bdev
)
1102 if (unlikely(lo
->lo_state
!= Lo_bound
))
1105 return figure_loop_size(lo
, lo
->lo_offset
, lo
->lo_sizelimit
);
1108 static int lo_ioctl(struct block_device
*bdev
, fmode_t mode
,
1109 unsigned int cmd
, unsigned long arg
)
1111 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1114 mutex_lock_nested(&lo
->lo_ctl_mutex
, 1);
1117 err
= loop_set_fd(lo
, mode
, bdev
, arg
);
1119 case LOOP_CHANGE_FD
:
1120 err
= loop_change_fd(lo
, bdev
, arg
);
1123 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1124 err
= loop_clr_fd(lo
);
1128 case LOOP_SET_STATUS
:
1130 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1131 err
= loop_set_status_old(lo
,
1132 (struct loop_info __user
*)arg
);
1134 case LOOP_GET_STATUS
:
1135 err
= loop_get_status_old(lo
, (struct loop_info __user
*) arg
);
1137 case LOOP_SET_STATUS64
:
1139 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1140 err
= loop_set_status64(lo
,
1141 (struct loop_info64 __user
*) arg
);
1143 case LOOP_GET_STATUS64
:
1144 err
= loop_get_status64(lo
, (struct loop_info64 __user
*) arg
);
1146 case LOOP_SET_CAPACITY
:
1148 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1149 err
= loop_set_capacity(lo
, bdev
);
1152 err
= lo
->ioctl
? lo
->ioctl(lo
, cmd
, arg
) : -EINVAL
;
1154 mutex_unlock(&lo
->lo_ctl_mutex
);
1160 #ifdef CONFIG_COMPAT
1161 struct compat_loop_info
{
1162 compat_int_t lo_number
; /* ioctl r/o */
1163 compat_dev_t lo_device
; /* ioctl r/o */
1164 compat_ulong_t lo_inode
; /* ioctl r/o */
1165 compat_dev_t lo_rdevice
; /* ioctl r/o */
1166 compat_int_t lo_offset
;
1167 compat_int_t lo_encrypt_type
;
1168 compat_int_t lo_encrypt_key_size
; /* ioctl w/o */
1169 compat_int_t lo_flags
; /* ioctl r/o */
1170 char lo_name
[LO_NAME_SIZE
];
1171 unsigned char lo_encrypt_key
[LO_KEY_SIZE
]; /* ioctl w/o */
1172 compat_ulong_t lo_init
[2];
1177 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1178 * - noinlined to reduce stack space usage in main part of driver
1181 loop_info64_from_compat(const struct compat_loop_info __user
*arg
,
1182 struct loop_info64
*info64
)
1184 struct compat_loop_info info
;
1186 if (copy_from_user(&info
, arg
, sizeof(info
)))
1189 memset(info64
, 0, sizeof(*info64
));
1190 info64
->lo_number
= info
.lo_number
;
1191 info64
->lo_device
= info
.lo_device
;
1192 info64
->lo_inode
= info
.lo_inode
;
1193 info64
->lo_rdevice
= info
.lo_rdevice
;
1194 info64
->lo_offset
= info
.lo_offset
;
1195 info64
->lo_sizelimit
= 0;
1196 info64
->lo_encrypt_type
= info
.lo_encrypt_type
;
1197 info64
->lo_encrypt_key_size
= info
.lo_encrypt_key_size
;
1198 info64
->lo_flags
= info
.lo_flags
;
1199 info64
->lo_init
[0] = info
.lo_init
[0];
1200 info64
->lo_init
[1] = info
.lo_init
[1];
1201 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1202 memcpy(info64
->lo_crypt_name
, info
.lo_name
, LO_NAME_SIZE
);
1204 memcpy(info64
->lo_file_name
, info
.lo_name
, LO_NAME_SIZE
);
1205 memcpy(info64
->lo_encrypt_key
, info
.lo_encrypt_key
, LO_KEY_SIZE
);
1210 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1211 * - noinlined to reduce stack space usage in main part of driver
1214 loop_info64_to_compat(const struct loop_info64
*info64
,
1215 struct compat_loop_info __user
*arg
)
1217 struct compat_loop_info info
;
1219 memset(&info
, 0, sizeof(info
));
1220 info
.lo_number
= info64
->lo_number
;
1221 info
.lo_device
= info64
->lo_device
;
1222 info
.lo_inode
= info64
->lo_inode
;
1223 info
.lo_rdevice
= info64
->lo_rdevice
;
1224 info
.lo_offset
= info64
->lo_offset
;
1225 info
.lo_encrypt_type
= info64
->lo_encrypt_type
;
1226 info
.lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1227 info
.lo_flags
= info64
->lo_flags
;
1228 info
.lo_init
[0] = info64
->lo_init
[0];
1229 info
.lo_init
[1] = info64
->lo_init
[1];
1230 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1231 memcpy(info
.lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1233 memcpy(info
.lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1234 memcpy(info
.lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1236 /* error in case values were truncated */
1237 if (info
.lo_device
!= info64
->lo_device
||
1238 info
.lo_rdevice
!= info64
->lo_rdevice
||
1239 info
.lo_inode
!= info64
->lo_inode
||
1240 info
.lo_offset
!= info64
->lo_offset
||
1241 info
.lo_init
[0] != info64
->lo_init
[0] ||
1242 info
.lo_init
[1] != info64
->lo_init
[1])
1245 if (copy_to_user(arg
, &info
, sizeof(info
)))
1251 loop_set_status_compat(struct loop_device
*lo
,
1252 const struct compat_loop_info __user
*arg
)
1254 struct loop_info64 info64
;
1257 ret
= loop_info64_from_compat(arg
, &info64
);
1260 return loop_set_status(lo
, &info64
);
1264 loop_get_status_compat(struct loop_device
*lo
,
1265 struct compat_loop_info __user
*arg
)
1267 struct loop_info64 info64
;
1273 err
= loop_get_status(lo
, &info64
);
1275 err
= loop_info64_to_compat(&info64
, arg
);
1279 static int lo_compat_ioctl(struct block_device
*bdev
, fmode_t mode
,
1280 unsigned int cmd
, unsigned long arg
)
1282 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1286 case LOOP_SET_STATUS
:
1287 mutex_lock(&lo
->lo_ctl_mutex
);
1288 err
= loop_set_status_compat(
1289 lo
, (const struct compat_loop_info __user
*) arg
);
1290 mutex_unlock(&lo
->lo_ctl_mutex
);
1292 case LOOP_GET_STATUS
:
1293 mutex_lock(&lo
->lo_ctl_mutex
);
1294 err
= loop_get_status_compat(
1295 lo
, (struct compat_loop_info __user
*) arg
);
1296 mutex_unlock(&lo
->lo_ctl_mutex
);
1298 case LOOP_SET_CAPACITY
:
1300 case LOOP_GET_STATUS64
:
1301 case LOOP_SET_STATUS64
:
1302 arg
= (unsigned long) compat_ptr(arg
);
1304 case LOOP_CHANGE_FD
:
1305 err
= lo_ioctl(bdev
, mode
, cmd
, arg
);
1315 static int lo_open(struct block_device
*bdev
, fmode_t mode
)
1317 struct loop_device
*lo
;
1320 mutex_lock(&loop_index_mutex
);
1321 lo
= bdev
->bd_disk
->private_data
;
1327 mutex_lock(&lo
->lo_ctl_mutex
);
1329 mutex_unlock(&lo
->lo_ctl_mutex
);
1331 mutex_unlock(&loop_index_mutex
);
1335 static void lo_release(struct gendisk
*disk
, fmode_t mode
)
1337 struct loop_device
*lo
= disk
->private_data
;
1340 mutex_lock(&lo
->lo_ctl_mutex
);
1342 if (--lo
->lo_refcnt
)
1345 if (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) {
1347 * In autoclear mode, stop the loop thread
1348 * and remove configuration after last close.
1350 err
= loop_clr_fd(lo
);
1355 * Otherwise keep thread (if running) and config,
1356 * but flush possible ongoing bios in thread.
1362 mutex_unlock(&lo
->lo_ctl_mutex
);
1365 static const struct block_device_operations lo_fops
= {
1366 .owner
= THIS_MODULE
,
1368 .release
= lo_release
,
1370 #ifdef CONFIG_COMPAT
1371 .compat_ioctl
= lo_compat_ioctl
,
1376 * And now the modules code and kernel interface.
1378 static int max_loop
;
1379 module_param(max_loop
, int, S_IRUGO
);
1380 MODULE_PARM_DESC(max_loop
, "Maximum number of loop devices");
1381 module_param(max_part
, int, S_IRUGO
);
1382 MODULE_PARM_DESC(max_part
, "Maximum number of partitions per loop device");
1383 MODULE_LICENSE("GPL");
1384 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR
);
1386 int loop_register_transfer(struct loop_func_table
*funcs
)
1388 unsigned int n
= funcs
->number
;
1390 if (n
>= MAX_LO_CRYPT
|| xfer_funcs
[n
])
1392 xfer_funcs
[n
] = funcs
;
1396 static int unregister_transfer_cb(int id
, void *ptr
, void *data
)
1398 struct loop_device
*lo
= ptr
;
1399 struct loop_func_table
*xfer
= data
;
1401 mutex_lock(&lo
->lo_ctl_mutex
);
1402 if (lo
->lo_encryption
== xfer
)
1403 loop_release_xfer(lo
);
1404 mutex_unlock(&lo
->lo_ctl_mutex
);
1408 int loop_unregister_transfer(int number
)
1410 unsigned int n
= number
;
1411 struct loop_func_table
*xfer
;
1413 if (n
== 0 || n
>= MAX_LO_CRYPT
|| (xfer
= xfer_funcs
[n
]) == NULL
)
1416 xfer_funcs
[n
] = NULL
;
1417 idr_for_each(&loop_index_idr
, &unregister_transfer_cb
, xfer
);
1421 EXPORT_SYMBOL(loop_register_transfer
);
1422 EXPORT_SYMBOL(loop_unregister_transfer
);
1424 static int loop_queue_rq(struct blk_mq_hw_ctx
*hctx
,
1425 const struct blk_mq_queue_data
*bd
)
1427 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(bd
->rq
);
1429 blk_mq_start_request(bd
->rq
);
1431 if (cmd
->rq
->cmd_flags
& REQ_WRITE
) {
1432 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1433 bool need_sched
= true;
1435 spin_lock_irq(&lo
->lo_lock
);
1436 if (lo
->write_started
)
1439 lo
->write_started
= true;
1440 list_add_tail(&cmd
->list
, &lo
->write_cmd_head
);
1441 spin_unlock_irq(&lo
->lo_lock
);
1444 queue_work(loop_wq
, &lo
->write_work
);
1446 queue_work(loop_wq
, &cmd
->read_work
);
1449 return BLK_MQ_RQ_QUEUE_OK
;
1452 static void loop_handle_cmd(struct loop_cmd
*cmd
)
1454 const bool write
= cmd
->rq
->cmd_flags
& REQ_WRITE
;
1455 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1458 if (lo
->lo_state
!= Lo_bound
)
1461 if (write
&& (lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
1464 ret
= do_req_filebacked(lo
, cmd
->rq
);
1468 cmd
->rq
->errors
= -EIO
;
1469 blk_mq_complete_request(cmd
->rq
);
1472 static void loop_queue_write_work(struct work_struct
*work
)
1474 struct loop_device
*lo
=
1475 container_of(work
, struct loop_device
, write_work
);
1476 LIST_HEAD(cmd_list
);
1478 spin_lock_irq(&lo
->lo_lock
);
1480 list_splice_init(&lo
->write_cmd_head
, &cmd_list
);
1481 spin_unlock_irq(&lo
->lo_lock
);
1483 while (!list_empty(&cmd_list
)) {
1484 struct loop_cmd
*cmd
= list_first_entry(&cmd_list
,
1485 struct loop_cmd
, list
);
1486 list_del_init(&cmd
->list
);
1487 loop_handle_cmd(cmd
);
1490 spin_lock_irq(&lo
->lo_lock
);
1491 if (!list_empty(&lo
->write_cmd_head
))
1493 lo
->write_started
= false;
1494 spin_unlock_irq(&lo
->lo_lock
);
1497 static void loop_queue_read_work(struct work_struct
*work
)
1499 struct loop_cmd
*cmd
=
1500 container_of(work
, struct loop_cmd
, read_work
);
1502 loop_handle_cmd(cmd
);
1505 static int loop_init_request(void *data
, struct request
*rq
,
1506 unsigned int hctx_idx
, unsigned int request_idx
,
1507 unsigned int numa_node
)
1509 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
1512 INIT_WORK(&cmd
->read_work
, loop_queue_read_work
);
1517 static struct blk_mq_ops loop_mq_ops
= {
1518 .queue_rq
= loop_queue_rq
,
1519 .map_queue
= blk_mq_map_queue
,
1520 .init_request
= loop_init_request
,
1523 static int loop_add(struct loop_device
**l
, int i
)
1525 struct loop_device
*lo
;
1526 struct gendisk
*disk
;
1530 lo
= kzalloc(sizeof(*lo
), GFP_KERNEL
);
1534 lo
->lo_state
= Lo_unbound
;
1536 /* allocate id, if @id >= 0, we're requesting that specific id */
1538 err
= idr_alloc(&loop_index_idr
, lo
, i
, i
+ 1, GFP_KERNEL
);
1542 err
= idr_alloc(&loop_index_idr
, lo
, 0, 0, GFP_KERNEL
);
1549 lo
->tag_set
.ops
= &loop_mq_ops
;
1550 lo
->tag_set
.nr_hw_queues
= 1;
1551 lo
->tag_set
.queue_depth
= 128;
1552 lo
->tag_set
.numa_node
= NUMA_NO_NODE
;
1553 lo
->tag_set
.cmd_size
= sizeof(struct loop_cmd
);
1554 lo
->tag_set
.flags
= BLK_MQ_F_SHOULD_MERGE
| BLK_MQ_F_SG_MERGE
;
1555 lo
->tag_set
.driver_data
= lo
;
1557 err
= blk_mq_alloc_tag_set(&lo
->tag_set
);
1561 lo
->lo_queue
= blk_mq_init_queue(&lo
->tag_set
);
1562 if (IS_ERR_OR_NULL(lo
->lo_queue
)) {
1563 err
= PTR_ERR(lo
->lo_queue
);
1564 goto out_cleanup_tags
;
1566 lo
->lo_queue
->queuedata
= lo
;
1568 INIT_LIST_HEAD(&lo
->write_cmd_head
);
1569 INIT_WORK(&lo
->write_work
, loop_queue_write_work
);
1571 disk
= lo
->lo_disk
= alloc_disk(1 << part_shift
);
1573 goto out_free_queue
;
1576 * Disable partition scanning by default. The in-kernel partition
1577 * scanning can be requested individually per-device during its
1578 * setup. Userspace can always add and remove partitions from all
1579 * devices. The needed partition minors are allocated from the
1580 * extended minor space, the main loop device numbers will continue
1581 * to match the loop minors, regardless of the number of partitions
1584 * If max_part is given, partition scanning is globally enabled for
1585 * all loop devices. The minors for the main loop devices will be
1586 * multiples of max_part.
1588 * Note: Global-for-all-devices, set-only-at-init, read-only module
1589 * parameteters like 'max_loop' and 'max_part' make things needlessly
1590 * complicated, are too static, inflexible and may surprise
1591 * userspace tools. Parameters like this in general should be avoided.
1594 disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1595 disk
->flags
|= GENHD_FL_EXT_DEVT
;
1596 mutex_init(&lo
->lo_ctl_mutex
);
1598 spin_lock_init(&lo
->lo_lock
);
1599 disk
->major
= LOOP_MAJOR
;
1600 disk
->first_minor
= i
<< part_shift
;
1601 disk
->fops
= &lo_fops
;
1602 disk
->private_data
= lo
;
1603 disk
->queue
= lo
->lo_queue
;
1604 sprintf(disk
->disk_name
, "loop%d", i
);
1607 return lo
->lo_number
;
1610 blk_cleanup_queue(lo
->lo_queue
);
1612 blk_mq_free_tag_set(&lo
->tag_set
);
1614 idr_remove(&loop_index_idr
, i
);
1621 static void loop_remove(struct loop_device
*lo
)
1623 blk_cleanup_queue(lo
->lo_queue
);
1624 del_gendisk(lo
->lo_disk
);
1625 blk_mq_free_tag_set(&lo
->tag_set
);
1626 put_disk(lo
->lo_disk
);
1630 static int find_free_cb(int id
, void *ptr
, void *data
)
1632 struct loop_device
*lo
= ptr
;
1633 struct loop_device
**l
= data
;
1635 if (lo
->lo_state
== Lo_unbound
) {
1642 static int loop_lookup(struct loop_device
**l
, int i
)
1644 struct loop_device
*lo
;
1650 err
= idr_for_each(&loop_index_idr
, &find_free_cb
, &lo
);
1653 ret
= lo
->lo_number
;
1658 /* lookup and return a specific i */
1659 lo
= idr_find(&loop_index_idr
, i
);
1662 ret
= lo
->lo_number
;
1668 static struct kobject
*loop_probe(dev_t dev
, int *part
, void *data
)
1670 struct loop_device
*lo
;
1671 struct kobject
*kobj
;
1674 mutex_lock(&loop_index_mutex
);
1675 err
= loop_lookup(&lo
, MINOR(dev
) >> part_shift
);
1677 err
= loop_add(&lo
, MINOR(dev
) >> part_shift
);
1681 kobj
= get_disk(lo
->lo_disk
);
1682 mutex_unlock(&loop_index_mutex
);
1688 static long loop_control_ioctl(struct file
*file
, unsigned int cmd
,
1691 struct loop_device
*lo
;
1694 mutex_lock(&loop_index_mutex
);
1697 ret
= loop_lookup(&lo
, parm
);
1702 ret
= loop_add(&lo
, parm
);
1704 case LOOP_CTL_REMOVE
:
1705 ret
= loop_lookup(&lo
, parm
);
1708 mutex_lock(&lo
->lo_ctl_mutex
);
1709 if (lo
->lo_state
!= Lo_unbound
) {
1711 mutex_unlock(&lo
->lo_ctl_mutex
);
1714 if (lo
->lo_refcnt
> 0) {
1716 mutex_unlock(&lo
->lo_ctl_mutex
);
1719 lo
->lo_disk
->private_data
= NULL
;
1720 mutex_unlock(&lo
->lo_ctl_mutex
);
1721 idr_remove(&loop_index_idr
, lo
->lo_number
);
1724 case LOOP_CTL_GET_FREE
:
1725 ret
= loop_lookup(&lo
, -1);
1728 ret
= loop_add(&lo
, -1);
1730 mutex_unlock(&loop_index_mutex
);
1735 static const struct file_operations loop_ctl_fops
= {
1736 .open
= nonseekable_open
,
1737 .unlocked_ioctl
= loop_control_ioctl
,
1738 .compat_ioctl
= loop_control_ioctl
,
1739 .owner
= THIS_MODULE
,
1740 .llseek
= noop_llseek
,
1743 static struct miscdevice loop_misc
= {
1744 .minor
= LOOP_CTRL_MINOR
,
1745 .name
= "loop-control",
1746 .fops
= &loop_ctl_fops
,
1749 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR
);
1750 MODULE_ALIAS("devname:loop-control");
1752 static int __init
loop_init(void)
1755 unsigned long range
;
1756 struct loop_device
*lo
;
1759 err
= misc_register(&loop_misc
);
1765 part_shift
= fls(max_part
);
1768 * Adjust max_part according to part_shift as it is exported
1769 * to user space so that user can decide correct minor number
1770 * if [s]he want to create more devices.
1772 * Note that -1 is required because partition 0 is reserved
1773 * for the whole disk.
1775 max_part
= (1UL << part_shift
) - 1;
1778 if ((1UL << part_shift
) > DISK_MAX_PARTS
) {
1783 if (max_loop
> 1UL << (MINORBITS
- part_shift
)) {
1789 * If max_loop is specified, create that many devices upfront.
1790 * This also becomes a hard limit. If max_loop is not specified,
1791 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1792 * init time. Loop devices can be requested on-demand with the
1793 * /dev/loop-control interface, or be instantiated by accessing
1794 * a 'dead' device node.
1798 range
= max_loop
<< part_shift
;
1800 nr
= CONFIG_BLK_DEV_LOOP_MIN_COUNT
;
1801 range
= 1UL << MINORBITS
;
1804 if (register_blkdev(LOOP_MAJOR
, "loop")) {
1809 loop_wq
= alloc_workqueue("kloopd",
1810 WQ_MEM_RECLAIM
| WQ_HIGHPRI
| WQ_UNBOUND
, 0);
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 destroy_workqueue(loop_wq
);
1855 misc_deregister(&loop_misc
);
1858 module_init(loop_init
);
1859 module_exit(loop_exit
);
1862 static int __init
max_loop_setup(char *str
)
1864 max_loop
= simple_strtol(str
, NULL
, 0);
1868 __setup("max_loop=", max_loop_setup
);