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
)
466 bio_list_add(&lo
->lo_bio_list
, bio
);
470 * Grab first pending buffer
472 static struct bio
*loop_get_bio(struct loop_device
*lo
)
474 return bio_list_pop(&lo
->lo_bio_list
);
477 static void loop_make_request(struct request_queue
*q
, struct bio
*old_bio
)
479 struct loop_device
*lo
= q
->queuedata
;
480 int rw
= bio_rw(old_bio
);
485 BUG_ON(!lo
|| (rw
!= READ
&& rw
!= WRITE
));
487 spin_lock_irq(&lo
->lo_lock
);
488 if (lo
->lo_state
!= Lo_bound
)
490 if (unlikely(rw
== WRITE
&& (lo
->lo_flags
& LO_FLAGS_READ_ONLY
)))
492 loop_add_bio(lo
, old_bio
);
493 wake_up(&lo
->lo_event
);
494 spin_unlock_irq(&lo
->lo_lock
);
498 spin_unlock_irq(&lo
->lo_lock
);
499 bio_io_error(old_bio
);
502 struct switch_request
{
504 struct completion wait
;
507 static void do_loop_switch(struct loop_device
*, struct switch_request
*);
509 static inline void loop_handle_bio(struct loop_device
*lo
, struct bio
*bio
)
511 if (unlikely(!bio
->bi_bdev
)) {
512 do_loop_switch(lo
, bio
->bi_private
);
515 int ret
= do_bio_filebacked(lo
, bio
);
521 * worker thread that handles reads/writes to file backed loop devices,
522 * to avoid blocking in our make_request_fn. it also does loop decrypting
523 * on reads for block backed loop, as that is too heavy to do from
524 * b_end_io context where irqs may be disabled.
526 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
527 * calling kthread_stop(). Therefore once kthread_should_stop() is
528 * true, make_request will not place any more requests. Therefore
529 * once kthread_should_stop() is true and lo_bio is NULL, we are
530 * done with the loop.
532 static int loop_thread(void *data
)
534 struct loop_device
*lo
= data
;
537 set_user_nice(current
, -20);
539 while (!kthread_should_stop() || !bio_list_empty(&lo
->lo_bio_list
)) {
541 wait_event_interruptible(lo
->lo_event
,
542 !bio_list_empty(&lo
->lo_bio_list
) ||
543 kthread_should_stop());
545 if (bio_list_empty(&lo
->lo_bio_list
))
547 spin_lock_irq(&lo
->lo_lock
);
548 bio
= loop_get_bio(lo
);
549 spin_unlock_irq(&lo
->lo_lock
);
552 loop_handle_bio(lo
, bio
);
559 * loop_switch performs the hard work of switching a backing store.
560 * First it needs to flush existing IO, it does this by sending a magic
561 * BIO down the pipe. The completion of this BIO does the actual switch.
563 static int loop_switch(struct loop_device
*lo
, struct file
*file
)
565 struct switch_request w
;
566 struct bio
*bio
= bio_alloc(GFP_KERNEL
, 0);
569 init_completion(&w
.wait
);
571 bio
->bi_private
= &w
;
573 loop_make_request(lo
->lo_queue
, bio
);
574 wait_for_completion(&w
.wait
);
579 * Helper to flush the IOs in loop, but keeping loop thread running
581 static int loop_flush(struct loop_device
*lo
)
583 /* loop not yet configured, no running thread, nothing to flush */
587 return loop_switch(lo
, NULL
);
591 * Do the actual switch; called from the BIO completion routine
593 static void do_loop_switch(struct loop_device
*lo
, struct switch_request
*p
)
595 struct file
*file
= p
->file
;
596 struct file
*old_file
= lo
->lo_backing_file
;
597 struct address_space
*mapping
;
599 /* if no new file, only flush of queued bios requested */
603 mapping
= file
->f_mapping
;
604 mapping_set_gfp_mask(old_file
->f_mapping
, lo
->old_gfp_mask
);
605 lo
->lo_backing_file
= file
;
606 lo
->lo_blocksize
= S_ISBLK(mapping
->host
->i_mode
) ?
607 mapping
->host
->i_bdev
->bd_block_size
: PAGE_SIZE
;
608 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
609 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
616 * loop_change_fd switched the backing store of a loopback device to
617 * a new file. This is useful for operating system installers to free up
618 * the original file and in High Availability environments to switch to
619 * an alternative location for the content in case of server meltdown.
620 * This can only work if the loop device is used read-only, and if the
621 * new backing store is the same size and type as the old backing store.
623 static int loop_change_fd(struct loop_device
*lo
, struct block_device
*bdev
,
626 struct file
*file
, *old_file
;
631 if (lo
->lo_state
!= Lo_bound
)
634 /* the loop device has to be read-only */
636 if (!(lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
644 inode
= file
->f_mapping
->host
;
645 old_file
= lo
->lo_backing_file
;
649 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
652 /* size of the new backing store needs to be the same */
653 if (get_loop_size(lo
, file
) != get_loop_size(lo
, old_file
))
657 error
= loop_switch(lo
, file
);
662 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
663 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
672 static inline int is_loop_device(struct file
*file
)
674 struct inode
*i
= file
->f_mapping
->host
;
676 return i
&& S_ISBLK(i
->i_mode
) && MAJOR(i
->i_rdev
) == LOOP_MAJOR
;
679 /* loop sysfs attributes */
681 static ssize_t
loop_attr_show(struct device
*dev
, char *page
,
682 ssize_t (*callback
)(struct loop_device
*, char *))
684 struct gendisk
*disk
= dev_to_disk(dev
);
685 struct loop_device
*lo
= disk
->private_data
;
687 return callback(lo
, page
);
690 #define LOOP_ATTR_RO(_name) \
691 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
692 static ssize_t loop_attr_do_show_##_name(struct device *d, \
693 struct device_attribute *attr, char *b) \
695 return loop_attr_show(d, b, loop_attr_##_name##_show); \
697 static struct device_attribute loop_attr_##_name = \
698 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
700 static ssize_t
loop_attr_backing_file_show(struct loop_device
*lo
, char *buf
)
705 spin_lock_irq(&lo
->lo_lock
);
706 if (lo
->lo_backing_file
)
707 p
= d_path(&lo
->lo_backing_file
->f_path
, buf
, PAGE_SIZE
- 1);
708 spin_unlock_irq(&lo
->lo_lock
);
710 if (IS_ERR_OR_NULL(p
))
714 memmove(buf
, p
, ret
);
722 static ssize_t
loop_attr_offset_show(struct loop_device
*lo
, char *buf
)
724 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_offset
);
727 static ssize_t
loop_attr_sizelimit_show(struct loop_device
*lo
, char *buf
)
729 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_sizelimit
);
732 static ssize_t
loop_attr_autoclear_show(struct loop_device
*lo
, char *buf
)
734 int autoclear
= (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
);
736 return sprintf(buf
, "%s\n", autoclear
? "1" : "0");
739 static ssize_t
loop_attr_partscan_show(struct loop_device
*lo
, char *buf
)
741 int partscan
= (lo
->lo_flags
& LO_FLAGS_PARTSCAN
);
743 return sprintf(buf
, "%s\n", partscan
? "1" : "0");
746 LOOP_ATTR_RO(backing_file
);
747 LOOP_ATTR_RO(offset
);
748 LOOP_ATTR_RO(sizelimit
);
749 LOOP_ATTR_RO(autoclear
);
750 LOOP_ATTR_RO(partscan
);
752 static struct attribute
*loop_attrs
[] = {
753 &loop_attr_backing_file
.attr
,
754 &loop_attr_offset
.attr
,
755 &loop_attr_sizelimit
.attr
,
756 &loop_attr_autoclear
.attr
,
757 &loop_attr_partscan
.attr
,
761 static struct attribute_group loop_attribute_group
= {
766 static int loop_sysfs_init(struct loop_device
*lo
)
768 return sysfs_create_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
769 &loop_attribute_group
);
772 static void loop_sysfs_exit(struct loop_device
*lo
)
774 sysfs_remove_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
775 &loop_attribute_group
);
778 static void loop_config_discard(struct loop_device
*lo
)
780 struct file
*file
= lo
->lo_backing_file
;
781 struct inode
*inode
= file
->f_mapping
->host
;
782 struct request_queue
*q
= lo
->lo_queue
;
785 * We use punch hole to reclaim the free space used by the
786 * image a.k.a. discard. However we do support discard if
787 * encryption is enabled, because it may give an attacker
788 * useful information.
790 if ((!file
->f_op
->fallocate
) ||
791 lo
->lo_encrypt_key_size
) {
792 q
->limits
.discard_granularity
= 0;
793 q
->limits
.discard_alignment
= 0;
794 q
->limits
.max_discard_sectors
= 0;
795 q
->limits
.discard_zeroes_data
= 0;
796 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD
, q
);
800 q
->limits
.discard_granularity
= inode
->i_sb
->s_blocksize
;
801 q
->limits
.discard_alignment
= 0;
802 q
->limits
.max_discard_sectors
= UINT_MAX
>> 9;
803 q
->limits
.discard_zeroes_data
= 1;
804 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, q
);
807 static int loop_set_fd(struct loop_device
*lo
, fmode_t mode
,
808 struct block_device
*bdev
, unsigned int arg
)
810 struct file
*file
, *f
;
812 struct address_space
*mapping
;
813 unsigned lo_blocksize
;
818 /* This is safe, since we have a reference from open(). */
819 __module_get(THIS_MODULE
);
827 if (lo
->lo_state
!= Lo_unbound
)
830 /* Avoid recursion */
832 while (is_loop_device(f
)) {
833 struct loop_device
*l
;
835 if (f
->f_mapping
->host
->i_bdev
== bdev
)
838 l
= f
->f_mapping
->host
->i_bdev
->bd_disk
->private_data
;
839 if (l
->lo_state
== Lo_unbound
) {
843 f
= l
->lo_backing_file
;
846 mapping
= file
->f_mapping
;
847 inode
= mapping
->host
;
850 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
853 if (!(file
->f_mode
& FMODE_WRITE
) || !(mode
& FMODE_WRITE
) ||
855 lo_flags
|= LO_FLAGS_READ_ONLY
;
857 lo_blocksize
= S_ISBLK(inode
->i_mode
) ?
858 inode
->i_bdev
->bd_block_size
: PAGE_SIZE
;
861 size
= get_loop_size(lo
, file
);
862 if ((loff_t
)(sector_t
)size
!= size
)
867 set_device_ro(bdev
, (lo_flags
& LO_FLAGS_READ_ONLY
) != 0);
869 lo
->lo_blocksize
= lo_blocksize
;
870 lo
->lo_device
= bdev
;
871 lo
->lo_flags
= lo_flags
;
872 lo
->lo_backing_file
= file
;
873 lo
->transfer
= transfer_none
;
875 lo
->lo_sizelimit
= 0;
876 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
877 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
879 bio_list_init(&lo
->lo_bio_list
);
882 * set queue make_request_fn, and add limits based on lower level
885 blk_queue_make_request(lo
->lo_queue
, loop_make_request
);
886 lo
->lo_queue
->queuedata
= lo
;
888 if (!(lo_flags
& LO_FLAGS_READ_ONLY
) && file
->f_op
->fsync
)
889 blk_queue_flush(lo
->lo_queue
, REQ_FLUSH
);
891 set_capacity(lo
->lo_disk
, size
);
892 bd_set_size(bdev
, size
<< 9);
894 /* let user-space know about the new size */
895 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
897 set_blocksize(bdev
, lo_blocksize
);
899 lo
->lo_thread
= kthread_create(loop_thread
, lo
, "loop%d",
901 if (IS_ERR(lo
->lo_thread
)) {
902 error
= PTR_ERR(lo
->lo_thread
);
905 lo
->lo_state
= Lo_bound
;
906 wake_up_process(lo
->lo_thread
);
908 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
909 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
910 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
912 /* Grab the block_device to prevent its destruction after we
913 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
920 lo
->lo_thread
= NULL
;
921 lo
->lo_device
= NULL
;
922 lo
->lo_backing_file
= NULL
;
924 set_capacity(lo
->lo_disk
, 0);
925 invalidate_bdev(bdev
);
926 bd_set_size(bdev
, 0);
927 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
928 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
);
929 lo
->lo_state
= Lo_unbound
;
933 /* This is safe: open() is still holding a reference. */
934 module_put(THIS_MODULE
);
939 loop_release_xfer(struct loop_device
*lo
)
942 struct loop_func_table
*xfer
= lo
->lo_encryption
;
946 err
= xfer
->release(lo
);
948 lo
->lo_encryption
= NULL
;
949 module_put(xfer
->owner
);
955 loop_init_xfer(struct loop_device
*lo
, struct loop_func_table
*xfer
,
956 const struct loop_info64
*i
)
961 struct module
*owner
= xfer
->owner
;
963 if (!try_module_get(owner
))
966 err
= xfer
->init(lo
, i
);
970 lo
->lo_encryption
= xfer
;
975 static int loop_clr_fd(struct loop_device
*lo
)
977 struct file
*filp
= lo
->lo_backing_file
;
978 gfp_t gfp
= lo
->old_gfp_mask
;
979 struct block_device
*bdev
= lo
->lo_device
;
981 if (lo
->lo_state
!= Lo_bound
)
984 if (lo
->lo_refcnt
> 1) /* we needed one fd for the ioctl */
990 spin_lock_irq(&lo
->lo_lock
);
991 lo
->lo_state
= Lo_rundown
;
992 spin_unlock_irq(&lo
->lo_lock
);
994 kthread_stop(lo
->lo_thread
);
996 spin_lock_irq(&lo
->lo_lock
);
997 lo
->lo_backing_file
= NULL
;
998 spin_unlock_irq(&lo
->lo_lock
);
1000 loop_release_xfer(lo
);
1001 lo
->transfer
= NULL
;
1003 lo
->lo_device
= NULL
;
1004 lo
->lo_encryption
= NULL
;
1006 lo
->lo_sizelimit
= 0;
1007 lo
->lo_encrypt_key_size
= 0;
1008 lo
->lo_thread
= NULL
;
1009 memset(lo
->lo_encrypt_key
, 0, LO_KEY_SIZE
);
1010 memset(lo
->lo_crypt_name
, 0, LO_NAME_SIZE
);
1011 memset(lo
->lo_file_name
, 0, LO_NAME_SIZE
);
1014 invalidate_bdev(bdev
);
1016 set_capacity(lo
->lo_disk
, 0);
1017 loop_sysfs_exit(lo
);
1019 bd_set_size(bdev
, 0);
1020 /* let user-space know about this change */
1021 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1023 mapping_set_gfp_mask(filp
->f_mapping
, gfp
);
1024 lo
->lo_state
= Lo_unbound
;
1025 /* This is safe: open() is still holding a reference. */
1026 module_put(THIS_MODULE
);
1027 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
&& bdev
)
1028 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
1031 lo
->lo_disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1032 mutex_unlock(&lo
->lo_ctl_mutex
);
1034 * Need not hold lo_ctl_mutex to fput backing file.
1035 * Calling fput holding lo_ctl_mutex triggers a circular
1036 * lock dependency possibility warning as fput can take
1037 * bd_mutex which is usually taken before lo_ctl_mutex.
1044 loop_set_status(struct loop_device
*lo
, const struct loop_info64
*info
)
1047 struct loop_func_table
*xfer
;
1048 uid_t uid
= current_uid();
1050 if (lo
->lo_encrypt_key_size
&&
1051 lo
->lo_key_owner
!= uid
&&
1052 !capable(CAP_SYS_ADMIN
))
1054 if (lo
->lo_state
!= Lo_bound
)
1056 if ((unsigned int) info
->lo_encrypt_key_size
> LO_KEY_SIZE
)
1059 err
= loop_release_xfer(lo
);
1063 if (info
->lo_encrypt_type
) {
1064 unsigned int type
= info
->lo_encrypt_type
;
1066 if (type
>= MAX_LO_CRYPT
)
1068 xfer
= xfer_funcs
[type
];
1074 err
= loop_init_xfer(lo
, xfer
, info
);
1078 if (lo
->lo_offset
!= info
->lo_offset
||
1079 lo
->lo_sizelimit
!= info
->lo_sizelimit
) {
1080 if (figure_loop_size(lo
, info
->lo_offset
, info
->lo_sizelimit
))
1083 loop_config_discard(lo
);
1085 memcpy(lo
->lo_file_name
, info
->lo_file_name
, LO_NAME_SIZE
);
1086 memcpy(lo
->lo_crypt_name
, info
->lo_crypt_name
, LO_NAME_SIZE
);
1087 lo
->lo_file_name
[LO_NAME_SIZE
-1] = 0;
1088 lo
->lo_crypt_name
[LO_NAME_SIZE
-1] = 0;
1092 lo
->transfer
= xfer
->transfer
;
1093 lo
->ioctl
= xfer
->ioctl
;
1095 if ((lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) !=
1096 (info
->lo_flags
& LO_FLAGS_AUTOCLEAR
))
1097 lo
->lo_flags
^= LO_FLAGS_AUTOCLEAR
;
1099 if ((info
->lo_flags
& LO_FLAGS_PARTSCAN
) &&
1100 !(lo
->lo_flags
& LO_FLAGS_PARTSCAN
)) {
1101 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
1102 lo
->lo_disk
->flags
&= ~GENHD_FL_NO_PART_SCAN
;
1103 ioctl_by_bdev(lo
->lo_device
, BLKRRPART
, 0);
1106 lo
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1107 lo
->lo_init
[0] = info
->lo_init
[0];
1108 lo
->lo_init
[1] = info
->lo_init
[1];
1109 if (info
->lo_encrypt_key_size
) {
1110 memcpy(lo
->lo_encrypt_key
, info
->lo_encrypt_key
,
1111 info
->lo_encrypt_key_size
);
1112 lo
->lo_key_owner
= uid
;
1119 loop_get_status(struct loop_device
*lo
, struct loop_info64
*info
)
1121 struct file
*file
= lo
->lo_backing_file
;
1125 if (lo
->lo_state
!= Lo_bound
)
1127 error
= vfs_getattr(file
->f_path
.mnt
, file
->f_path
.dentry
, &stat
);
1130 memset(info
, 0, sizeof(*info
));
1131 info
->lo_number
= lo
->lo_number
;
1132 info
->lo_device
= huge_encode_dev(stat
.dev
);
1133 info
->lo_inode
= stat
.ino
;
1134 info
->lo_rdevice
= huge_encode_dev(lo
->lo_device
? stat
.rdev
: stat
.dev
);
1135 info
->lo_offset
= lo
->lo_offset
;
1136 info
->lo_sizelimit
= lo
->lo_sizelimit
;
1137 info
->lo_flags
= lo
->lo_flags
;
1138 memcpy(info
->lo_file_name
, lo
->lo_file_name
, LO_NAME_SIZE
);
1139 memcpy(info
->lo_crypt_name
, lo
->lo_crypt_name
, LO_NAME_SIZE
);
1140 info
->lo_encrypt_type
=
1141 lo
->lo_encryption
? lo
->lo_encryption
->number
: 0;
1142 if (lo
->lo_encrypt_key_size
&& capable(CAP_SYS_ADMIN
)) {
1143 info
->lo_encrypt_key_size
= lo
->lo_encrypt_key_size
;
1144 memcpy(info
->lo_encrypt_key
, lo
->lo_encrypt_key
,
1145 lo
->lo_encrypt_key_size
);
1151 loop_info64_from_old(const struct loop_info
*info
, struct loop_info64
*info64
)
1153 memset(info64
, 0, sizeof(*info64
));
1154 info64
->lo_number
= info
->lo_number
;
1155 info64
->lo_device
= info
->lo_device
;
1156 info64
->lo_inode
= info
->lo_inode
;
1157 info64
->lo_rdevice
= info
->lo_rdevice
;
1158 info64
->lo_offset
= info
->lo_offset
;
1159 info64
->lo_sizelimit
= 0;
1160 info64
->lo_encrypt_type
= info
->lo_encrypt_type
;
1161 info64
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1162 info64
->lo_flags
= info
->lo_flags
;
1163 info64
->lo_init
[0] = info
->lo_init
[0];
1164 info64
->lo_init
[1] = info
->lo_init
[1];
1165 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1166 memcpy(info64
->lo_crypt_name
, info
->lo_name
, LO_NAME_SIZE
);
1168 memcpy(info64
->lo_file_name
, info
->lo_name
, LO_NAME_SIZE
);
1169 memcpy(info64
->lo_encrypt_key
, info
->lo_encrypt_key
, LO_KEY_SIZE
);
1173 loop_info64_to_old(const struct loop_info64
*info64
, struct loop_info
*info
)
1175 memset(info
, 0, sizeof(*info
));
1176 info
->lo_number
= info64
->lo_number
;
1177 info
->lo_device
= info64
->lo_device
;
1178 info
->lo_inode
= info64
->lo_inode
;
1179 info
->lo_rdevice
= info64
->lo_rdevice
;
1180 info
->lo_offset
= info64
->lo_offset
;
1181 info
->lo_encrypt_type
= info64
->lo_encrypt_type
;
1182 info
->lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1183 info
->lo_flags
= info64
->lo_flags
;
1184 info
->lo_init
[0] = info64
->lo_init
[0];
1185 info
->lo_init
[1] = info64
->lo_init
[1];
1186 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1187 memcpy(info
->lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1189 memcpy(info
->lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1190 memcpy(info
->lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1192 /* error in case values were truncated */
1193 if (info
->lo_device
!= info64
->lo_device
||
1194 info
->lo_rdevice
!= info64
->lo_rdevice
||
1195 info
->lo_inode
!= info64
->lo_inode
||
1196 info
->lo_offset
!= info64
->lo_offset
)
1203 loop_set_status_old(struct loop_device
*lo
, const struct loop_info __user
*arg
)
1205 struct loop_info info
;
1206 struct loop_info64 info64
;
1208 if (copy_from_user(&info
, arg
, sizeof (struct loop_info
)))
1210 loop_info64_from_old(&info
, &info64
);
1211 return loop_set_status(lo
, &info64
);
1215 loop_set_status64(struct loop_device
*lo
, const struct loop_info64 __user
*arg
)
1217 struct loop_info64 info64
;
1219 if (copy_from_user(&info64
, arg
, sizeof (struct loop_info64
)))
1221 return loop_set_status(lo
, &info64
);
1225 loop_get_status_old(struct loop_device
*lo
, struct loop_info __user
*arg
) {
1226 struct loop_info info
;
1227 struct loop_info64 info64
;
1233 err
= loop_get_status(lo
, &info64
);
1235 err
= loop_info64_to_old(&info64
, &info
);
1236 if (!err
&& copy_to_user(arg
, &info
, sizeof(info
)))
1243 loop_get_status64(struct loop_device
*lo
, struct loop_info64 __user
*arg
) {
1244 struct loop_info64 info64
;
1250 err
= loop_get_status(lo
, &info64
);
1251 if (!err
&& copy_to_user(arg
, &info64
, sizeof(info64
)))
1257 static int loop_set_capacity(struct loop_device
*lo
, struct block_device
*bdev
)
1264 if (unlikely(lo
->lo_state
!= Lo_bound
))
1266 err
= figure_loop_size(lo
, lo
->lo_offset
, lo
->lo_sizelimit
);
1269 sec
= get_capacity(lo
->lo_disk
);
1270 /* the width of sector_t may be narrow for bit-shift */
1273 bd_set_size(bdev
, sz
);
1274 /* let user-space know about the new size */
1275 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1281 static int lo_ioctl(struct block_device
*bdev
, fmode_t mode
,
1282 unsigned int cmd
, unsigned long arg
)
1284 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1287 mutex_lock_nested(&lo
->lo_ctl_mutex
, 1);
1290 err
= loop_set_fd(lo
, mode
, bdev
, arg
);
1292 case LOOP_CHANGE_FD
:
1293 err
= loop_change_fd(lo
, bdev
, arg
);
1296 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1297 err
= loop_clr_fd(lo
);
1301 case LOOP_SET_STATUS
:
1303 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1304 err
= loop_set_status_old(lo
,
1305 (struct loop_info __user
*)arg
);
1307 case LOOP_GET_STATUS
:
1308 err
= loop_get_status_old(lo
, (struct loop_info __user
*) arg
);
1310 case LOOP_SET_STATUS64
:
1312 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1313 err
= loop_set_status64(lo
,
1314 (struct loop_info64 __user
*) arg
);
1316 case LOOP_GET_STATUS64
:
1317 err
= loop_get_status64(lo
, (struct loop_info64 __user
*) arg
);
1319 case LOOP_SET_CAPACITY
:
1321 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1322 err
= loop_set_capacity(lo
, bdev
);
1325 err
= lo
->ioctl
? lo
->ioctl(lo
, cmd
, arg
) : -EINVAL
;
1327 mutex_unlock(&lo
->lo_ctl_mutex
);
1333 #ifdef CONFIG_COMPAT
1334 struct compat_loop_info
{
1335 compat_int_t lo_number
; /* ioctl r/o */
1336 compat_dev_t lo_device
; /* ioctl r/o */
1337 compat_ulong_t lo_inode
; /* ioctl r/o */
1338 compat_dev_t lo_rdevice
; /* ioctl r/o */
1339 compat_int_t lo_offset
;
1340 compat_int_t lo_encrypt_type
;
1341 compat_int_t lo_encrypt_key_size
; /* ioctl w/o */
1342 compat_int_t lo_flags
; /* ioctl r/o */
1343 char lo_name
[LO_NAME_SIZE
];
1344 unsigned char lo_encrypt_key
[LO_KEY_SIZE
]; /* ioctl w/o */
1345 compat_ulong_t lo_init
[2];
1350 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1351 * - noinlined to reduce stack space usage in main part of driver
1354 loop_info64_from_compat(const struct compat_loop_info __user
*arg
,
1355 struct loop_info64
*info64
)
1357 struct compat_loop_info info
;
1359 if (copy_from_user(&info
, arg
, sizeof(info
)))
1362 memset(info64
, 0, sizeof(*info64
));
1363 info64
->lo_number
= info
.lo_number
;
1364 info64
->lo_device
= info
.lo_device
;
1365 info64
->lo_inode
= info
.lo_inode
;
1366 info64
->lo_rdevice
= info
.lo_rdevice
;
1367 info64
->lo_offset
= info
.lo_offset
;
1368 info64
->lo_sizelimit
= 0;
1369 info64
->lo_encrypt_type
= info
.lo_encrypt_type
;
1370 info64
->lo_encrypt_key_size
= info
.lo_encrypt_key_size
;
1371 info64
->lo_flags
= info
.lo_flags
;
1372 info64
->lo_init
[0] = info
.lo_init
[0];
1373 info64
->lo_init
[1] = info
.lo_init
[1];
1374 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1375 memcpy(info64
->lo_crypt_name
, info
.lo_name
, LO_NAME_SIZE
);
1377 memcpy(info64
->lo_file_name
, info
.lo_name
, LO_NAME_SIZE
);
1378 memcpy(info64
->lo_encrypt_key
, info
.lo_encrypt_key
, LO_KEY_SIZE
);
1383 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1384 * - noinlined to reduce stack space usage in main part of driver
1387 loop_info64_to_compat(const struct loop_info64
*info64
,
1388 struct compat_loop_info __user
*arg
)
1390 struct compat_loop_info info
;
1392 memset(&info
, 0, sizeof(info
));
1393 info
.lo_number
= info64
->lo_number
;
1394 info
.lo_device
= info64
->lo_device
;
1395 info
.lo_inode
= info64
->lo_inode
;
1396 info
.lo_rdevice
= info64
->lo_rdevice
;
1397 info
.lo_offset
= info64
->lo_offset
;
1398 info
.lo_encrypt_type
= info64
->lo_encrypt_type
;
1399 info
.lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1400 info
.lo_flags
= info64
->lo_flags
;
1401 info
.lo_init
[0] = info64
->lo_init
[0];
1402 info
.lo_init
[1] = info64
->lo_init
[1];
1403 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1404 memcpy(info
.lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1406 memcpy(info
.lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1407 memcpy(info
.lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1409 /* error in case values were truncated */
1410 if (info
.lo_device
!= info64
->lo_device
||
1411 info
.lo_rdevice
!= info64
->lo_rdevice
||
1412 info
.lo_inode
!= info64
->lo_inode
||
1413 info
.lo_offset
!= info64
->lo_offset
||
1414 info
.lo_init
[0] != info64
->lo_init
[0] ||
1415 info
.lo_init
[1] != info64
->lo_init
[1])
1418 if (copy_to_user(arg
, &info
, sizeof(info
)))
1424 loop_set_status_compat(struct loop_device
*lo
,
1425 const struct compat_loop_info __user
*arg
)
1427 struct loop_info64 info64
;
1430 ret
= loop_info64_from_compat(arg
, &info64
);
1433 return loop_set_status(lo
, &info64
);
1437 loop_get_status_compat(struct loop_device
*lo
,
1438 struct compat_loop_info __user
*arg
)
1440 struct loop_info64 info64
;
1446 err
= loop_get_status(lo
, &info64
);
1448 err
= loop_info64_to_compat(&info64
, arg
);
1452 static int lo_compat_ioctl(struct block_device
*bdev
, fmode_t mode
,
1453 unsigned int cmd
, unsigned long arg
)
1455 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1459 case LOOP_SET_STATUS
:
1460 mutex_lock(&lo
->lo_ctl_mutex
);
1461 err
= loop_set_status_compat(
1462 lo
, (const struct compat_loop_info __user
*) arg
);
1463 mutex_unlock(&lo
->lo_ctl_mutex
);
1465 case LOOP_GET_STATUS
:
1466 mutex_lock(&lo
->lo_ctl_mutex
);
1467 err
= loop_get_status_compat(
1468 lo
, (struct compat_loop_info __user
*) arg
);
1469 mutex_unlock(&lo
->lo_ctl_mutex
);
1471 case LOOP_SET_CAPACITY
:
1473 case LOOP_GET_STATUS64
:
1474 case LOOP_SET_STATUS64
:
1475 arg
= (unsigned long) compat_ptr(arg
);
1477 case LOOP_CHANGE_FD
:
1478 err
= lo_ioctl(bdev
, mode
, cmd
, arg
);
1488 static int lo_open(struct block_device
*bdev
, fmode_t mode
)
1490 struct loop_device
*lo
;
1493 mutex_lock(&loop_index_mutex
);
1494 lo
= bdev
->bd_disk
->private_data
;
1500 mutex_lock(&lo
->lo_ctl_mutex
);
1502 mutex_unlock(&lo
->lo_ctl_mutex
);
1504 mutex_unlock(&loop_index_mutex
);
1508 static int lo_release(struct gendisk
*disk
, fmode_t mode
)
1510 struct loop_device
*lo
= disk
->private_data
;
1513 mutex_lock(&lo
->lo_ctl_mutex
);
1515 if (--lo
->lo_refcnt
)
1518 if (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) {
1520 * In autoclear mode, stop the loop thread
1521 * and remove configuration after last close.
1523 err
= loop_clr_fd(lo
);
1528 * Otherwise keep thread (if running) and config,
1529 * but flush possible ongoing bios in thread.
1535 mutex_unlock(&lo
->lo_ctl_mutex
);
1540 static const struct block_device_operations lo_fops
= {
1541 .owner
= THIS_MODULE
,
1543 .release
= lo_release
,
1545 #ifdef CONFIG_COMPAT
1546 .compat_ioctl
= lo_compat_ioctl
,
1551 * And now the modules code and kernel interface.
1553 static int max_loop
;
1554 module_param(max_loop
, int, S_IRUGO
);
1555 MODULE_PARM_DESC(max_loop
, "Maximum number of loop devices");
1556 module_param(max_part
, int, S_IRUGO
);
1557 MODULE_PARM_DESC(max_part
, "Maximum number of partitions per loop device");
1558 MODULE_LICENSE("GPL");
1559 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR
);
1561 int loop_register_transfer(struct loop_func_table
*funcs
)
1563 unsigned int n
= funcs
->number
;
1565 if (n
>= MAX_LO_CRYPT
|| xfer_funcs
[n
])
1567 xfer_funcs
[n
] = funcs
;
1571 static int unregister_transfer_cb(int id
, void *ptr
, void *data
)
1573 struct loop_device
*lo
= ptr
;
1574 struct loop_func_table
*xfer
= data
;
1576 mutex_lock(&lo
->lo_ctl_mutex
);
1577 if (lo
->lo_encryption
== xfer
)
1578 loop_release_xfer(lo
);
1579 mutex_unlock(&lo
->lo_ctl_mutex
);
1583 int loop_unregister_transfer(int number
)
1585 unsigned int n
= number
;
1586 struct loop_func_table
*xfer
;
1588 if (n
== 0 || n
>= MAX_LO_CRYPT
|| (xfer
= xfer_funcs
[n
]) == NULL
)
1591 xfer_funcs
[n
] = NULL
;
1592 idr_for_each(&loop_index_idr
, &unregister_transfer_cb
, xfer
);
1596 EXPORT_SYMBOL(loop_register_transfer
);
1597 EXPORT_SYMBOL(loop_unregister_transfer
);
1599 static int loop_add(struct loop_device
**l
, int i
)
1601 struct loop_device
*lo
;
1602 struct gendisk
*disk
;
1605 lo
= kzalloc(sizeof(*lo
), GFP_KERNEL
);
1611 err
= idr_pre_get(&loop_index_idr
, GFP_KERNEL
);
1618 /* create specific i in the index */
1619 err
= idr_get_new_above(&loop_index_idr
, lo
, i
, &m
);
1620 if (err
>= 0 && i
!= m
) {
1621 idr_remove(&loop_index_idr
, m
);
1624 } else if (i
== -1) {
1627 /* get next free nr */
1628 err
= idr_get_new(&loop_index_idr
, lo
, &m
);
1637 lo
->lo_queue
= blk_alloc_queue(GFP_KERNEL
);
1641 disk
= lo
->lo_disk
= alloc_disk(1 << part_shift
);
1643 goto out_free_queue
;
1646 * Disable partition scanning by default. The in-kernel partition
1647 * scanning can be requested individually per-device during its
1648 * setup. Userspace can always add and remove partitions from all
1649 * devices. The needed partition minors are allocated from the
1650 * extended minor space, the main loop device numbers will continue
1651 * to match the loop minors, regardless of the number of partitions
1654 * If max_part is given, partition scanning is globally enabled for
1655 * all loop devices. The minors for the main loop devices will be
1656 * multiples of max_part.
1658 * Note: Global-for-all-devices, set-only-at-init, read-only module
1659 * parameteters like 'max_loop' and 'max_part' make things needlessly
1660 * complicated, are too static, inflexible and may surprise
1661 * userspace tools. Parameters like this in general should be avoided.
1664 disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1665 disk
->flags
|= GENHD_FL_EXT_DEVT
;
1666 mutex_init(&lo
->lo_ctl_mutex
);
1668 lo
->lo_thread
= NULL
;
1669 init_waitqueue_head(&lo
->lo_event
);
1670 spin_lock_init(&lo
->lo_lock
);
1671 disk
->major
= LOOP_MAJOR
;
1672 disk
->first_minor
= i
<< part_shift
;
1673 disk
->fops
= &lo_fops
;
1674 disk
->private_data
= lo
;
1675 disk
->queue
= lo
->lo_queue
;
1676 sprintf(disk
->disk_name
, "loop%d", i
);
1679 return lo
->lo_number
;
1682 blk_cleanup_queue(lo
->lo_queue
);
1684 idr_remove(&loop_index_idr
, i
);
1691 static void loop_remove(struct loop_device
*lo
)
1693 del_gendisk(lo
->lo_disk
);
1694 blk_cleanup_queue(lo
->lo_queue
);
1695 put_disk(lo
->lo_disk
);
1699 static int find_free_cb(int id
, void *ptr
, void *data
)
1701 struct loop_device
*lo
= ptr
;
1702 struct loop_device
**l
= data
;
1704 if (lo
->lo_state
== Lo_unbound
) {
1711 static int loop_lookup(struct loop_device
**l
, int i
)
1713 struct loop_device
*lo
;
1719 err
= idr_for_each(&loop_index_idr
, &find_free_cb
, &lo
);
1722 ret
= lo
->lo_number
;
1727 /* lookup and return a specific i */
1728 lo
= idr_find(&loop_index_idr
, i
);
1731 ret
= lo
->lo_number
;
1737 static struct kobject
*loop_probe(dev_t dev
, int *part
, void *data
)
1739 struct loop_device
*lo
;
1740 struct kobject
*kobj
;
1743 mutex_lock(&loop_index_mutex
);
1744 err
= loop_lookup(&lo
, MINOR(dev
) >> part_shift
);
1746 err
= loop_add(&lo
, MINOR(dev
) >> part_shift
);
1750 kobj
= get_disk(lo
->lo_disk
);
1751 mutex_unlock(&loop_index_mutex
);
1757 static long loop_control_ioctl(struct file
*file
, unsigned int cmd
,
1760 struct loop_device
*lo
;
1763 mutex_lock(&loop_index_mutex
);
1766 ret
= loop_lookup(&lo
, parm
);
1771 ret
= loop_add(&lo
, parm
);
1773 case LOOP_CTL_REMOVE
:
1774 ret
= loop_lookup(&lo
, parm
);
1777 mutex_lock(&lo
->lo_ctl_mutex
);
1778 if (lo
->lo_state
!= Lo_unbound
) {
1780 mutex_unlock(&lo
->lo_ctl_mutex
);
1783 if (lo
->lo_refcnt
> 0) {
1785 mutex_unlock(&lo
->lo_ctl_mutex
);
1788 lo
->lo_disk
->private_data
= NULL
;
1789 mutex_unlock(&lo
->lo_ctl_mutex
);
1790 idr_remove(&loop_index_idr
, lo
->lo_number
);
1793 case LOOP_CTL_GET_FREE
:
1794 ret
= loop_lookup(&lo
, -1);
1797 ret
= loop_add(&lo
, -1);
1799 mutex_unlock(&loop_index_mutex
);
1804 static const struct file_operations loop_ctl_fops
= {
1805 .open
= nonseekable_open
,
1806 .unlocked_ioctl
= loop_control_ioctl
,
1807 .compat_ioctl
= loop_control_ioctl
,
1808 .owner
= THIS_MODULE
,
1809 .llseek
= noop_llseek
,
1812 static struct miscdevice loop_misc
= {
1813 .minor
= LOOP_CTRL_MINOR
,
1814 .name
= "loop-control",
1815 .fops
= &loop_ctl_fops
,
1818 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR
);
1819 MODULE_ALIAS("devname:loop-control");
1821 static int __init
loop_init(void)
1824 unsigned long range
;
1825 struct loop_device
*lo
;
1828 err
= misc_register(&loop_misc
);
1834 part_shift
= fls(max_part
);
1837 * Adjust max_part according to part_shift as it is exported
1838 * to user space so that user can decide correct minor number
1839 * if [s]he want to create more devices.
1841 * Note that -1 is required because partition 0 is reserved
1842 * for the whole disk.
1844 max_part
= (1UL << part_shift
) - 1;
1847 if ((1UL << part_shift
) > DISK_MAX_PARTS
) {
1852 if (max_loop
> 1UL << (MINORBITS
- part_shift
)) {
1858 * If max_loop is specified, create that many devices upfront.
1859 * This also becomes a hard limit. If max_loop is not specified,
1860 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1861 * init time. Loop devices can be requested on-demand with the
1862 * /dev/loop-control interface, or be instantiated by accessing
1863 * a 'dead' device node.
1867 range
= max_loop
<< part_shift
;
1869 nr
= CONFIG_BLK_DEV_LOOP_MIN_COUNT
;
1870 range
= 1UL << MINORBITS
;
1873 if (register_blkdev(LOOP_MAJOR
, "loop")) {
1878 blk_register_region(MKDEV(LOOP_MAJOR
, 0), range
,
1879 THIS_MODULE
, loop_probe
, NULL
, NULL
);
1881 /* pre-create number of devices given by config or max_loop */
1882 mutex_lock(&loop_index_mutex
);
1883 for (i
= 0; i
< nr
; i
++)
1885 mutex_unlock(&loop_index_mutex
);
1887 printk(KERN_INFO
"loop: module loaded\n");
1891 misc_deregister(&loop_misc
);
1895 static int loop_exit_cb(int id
, void *ptr
, void *data
)
1897 struct loop_device
*lo
= ptr
;
1903 static void __exit
loop_exit(void)
1905 unsigned long range
;
1907 range
= max_loop
? max_loop
<< part_shift
: 1UL << MINORBITS
;
1909 idr_for_each(&loop_index_idr
, &loop_exit_cb
, NULL
);
1910 idr_remove_all(&loop_index_idr
);
1911 idr_destroy(&loop_index_idr
);
1913 blk_unregister_region(MKDEV(LOOP_MAJOR
, 0), range
);
1914 unregister_blkdev(LOOP_MAJOR
, "loop");
1916 misc_deregister(&loop_misc
);
1919 module_init(loop_init
);
1920 module_exit(loop_exit
);
1923 static int __init
max_loop_setup(char *str
)
1925 max_loop
= simple_strtol(str
, NULL
, 0);
1929 __setup("max_loop=", max_loop_setup
);