2 * linux/drivers/block/loop.c
4 * Written by Theodore Ts'o, 3/29/93
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
21 * Loadable modules and other fixes by AK, 1998
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
37 * Jens Axboe <axboe@suse.de>, Nov 2000
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
52 #include <linux/module.h>
53 #include <linux/moduleparam.h>
54 #include <linux/sched.h>
56 #include <linux/file.h>
57 #include <linux/stat.h>
58 #include <linux/errno.h>
59 #include <linux/major.h>
60 #include <linux/wait.h>
61 #include <linux/blkdev.h>
62 #include <linux/blkpg.h>
63 #include <linux/init.h>
64 #include <linux/swap.h>
65 #include <linux/slab.h>
66 #include <linux/loop.h>
67 #include <linux/compat.h>
68 #include <linux/suspend.h>
69 #include <linux/freezer.h>
70 #include <linux/mutex.h>
71 #include <linux/writeback.h>
72 #include <linux/buffer_head.h> /* for invalidate_bdev() */
73 #include <linux/completion.h>
74 #include <linux/highmem.h>
75 #include <linux/kthread.h>
76 #include <linux/splice.h>
77 #include <linux/sysfs.h>
79 #include <asm/uaccess.h>
81 static LIST_HEAD(loop_devices
);
82 static DEFINE_MUTEX(loop_devices_mutex
);
85 static int part_shift
;
90 static int transfer_none(struct loop_device
*lo
, int cmd
,
91 struct page
*raw_page
, unsigned raw_off
,
92 struct page
*loop_page
, unsigned loop_off
,
93 int size
, sector_t real_block
)
95 char *raw_buf
= kmap_atomic(raw_page
, KM_USER0
) + raw_off
;
96 char *loop_buf
= kmap_atomic(loop_page
, KM_USER1
) + loop_off
;
99 memcpy(loop_buf
, raw_buf
, size
);
101 memcpy(raw_buf
, loop_buf
, size
);
103 kunmap_atomic(loop_buf
, KM_USER1
);
104 kunmap_atomic(raw_buf
, KM_USER0
);
109 static int transfer_xor(struct loop_device
*lo
, int cmd
,
110 struct page
*raw_page
, unsigned raw_off
,
111 struct page
*loop_page
, unsigned loop_off
,
112 int size
, sector_t real_block
)
114 char *raw_buf
= kmap_atomic(raw_page
, KM_USER0
) + raw_off
;
115 char *loop_buf
= kmap_atomic(loop_page
, KM_USER1
) + loop_off
;
116 char *in
, *out
, *key
;
127 key
= lo
->lo_encrypt_key
;
128 keysize
= lo
->lo_encrypt_key_size
;
129 for (i
= 0; i
< size
; i
++)
130 *out
++ = *in
++ ^ key
[(i
& 511) % keysize
];
132 kunmap_atomic(loop_buf
, KM_USER1
);
133 kunmap_atomic(raw_buf
, KM_USER0
);
138 static int xor_init(struct loop_device
*lo
, const struct loop_info64
*info
)
140 if (unlikely(info
->lo_encrypt_key_size
<= 0))
145 static struct loop_func_table none_funcs
= {
146 .number
= LO_CRYPT_NONE
,
147 .transfer
= transfer_none
,
150 static struct loop_func_table xor_funcs
= {
151 .number
= LO_CRYPT_XOR
,
152 .transfer
= transfer_xor
,
156 /* xfer_funcs[0] is special - its release function is never called */
157 static struct loop_func_table
*xfer_funcs
[MAX_LO_CRYPT
] = {
162 static loff_t
get_loop_size(struct loop_device
*lo
, struct file
*file
)
164 loff_t size
, offset
, loopsize
;
166 /* Compute loopsize in bytes */
167 size
= i_size_read(file
->f_mapping
->host
);
168 offset
= lo
->lo_offset
;
169 loopsize
= size
- offset
;
170 if (lo
->lo_sizelimit
> 0 && lo
->lo_sizelimit
< loopsize
)
171 loopsize
= lo
->lo_sizelimit
;
174 * Unfortunately, if we want to do I/O on the device,
175 * the number of 512-byte sectors has to fit into a sector_t.
177 return loopsize
>> 9;
181 figure_loop_size(struct loop_device
*lo
)
183 loff_t size
= get_loop_size(lo
, lo
->lo_backing_file
);
184 sector_t x
= (sector_t
)size
;
186 if (unlikely((loff_t
)x
!= size
))
189 set_capacity(lo
->lo_disk
, x
);
194 lo_do_transfer(struct loop_device
*lo
, int cmd
,
195 struct page
*rpage
, unsigned roffs
,
196 struct page
*lpage
, unsigned loffs
,
197 int size
, sector_t rblock
)
199 if (unlikely(!lo
->transfer
))
202 return lo
->transfer(lo
, cmd
, rpage
, roffs
, lpage
, loffs
, size
, rblock
);
206 * do_lo_send_aops - helper for writing data to a loop device
208 * This is the fast version for backing filesystems which implement the address
209 * space operations write_begin and write_end.
211 static int do_lo_send_aops(struct loop_device
*lo
, struct bio_vec
*bvec
,
212 loff_t pos
, struct page
*unused
)
214 struct file
*file
= lo
->lo_backing_file
; /* kudos to NFsckingS */
215 struct address_space
*mapping
= file
->f_mapping
;
217 unsigned offset
, bv_offs
;
220 mutex_lock(&mapping
->host
->i_mutex
);
221 index
= pos
>> PAGE_CACHE_SHIFT
;
222 offset
= pos
& ((pgoff_t
)PAGE_CACHE_SIZE
- 1);
223 bv_offs
= bvec
->bv_offset
;
227 unsigned size
, copied
;
232 IV
= ((sector_t
)index
<< (PAGE_CACHE_SHIFT
- 9))+(offset
>> 9);
233 size
= PAGE_CACHE_SIZE
- offset
;
237 ret
= pagecache_write_begin(file
, mapping
, pos
, size
, 0,
242 file_update_time(file
);
244 transfer_result
= lo_do_transfer(lo
, WRITE
, page
, offset
,
245 bvec
->bv_page
, bv_offs
, size
, IV
);
247 if (unlikely(transfer_result
))
250 ret
= pagecache_write_end(file
, mapping
, pos
, size
, copied
,
252 if (ret
< 0 || ret
!= copied
)
255 if (unlikely(transfer_result
))
266 mutex_unlock(&mapping
->host
->i_mutex
);
274 * __do_lo_send_write - helper for writing data to a loop device
276 * This helper just factors out common code between do_lo_send_direct_write()
277 * and do_lo_send_write().
279 static int __do_lo_send_write(struct file
*file
,
280 u8
*buf
, const int len
, loff_t pos
)
283 mm_segment_t old_fs
= get_fs();
286 bw
= file
->f_op
->write(file
, buf
, len
, &pos
);
288 if (likely(bw
== len
))
290 printk(KERN_ERR
"loop: Write error at byte offset %llu, length %i.\n",
291 (unsigned long long)pos
, len
);
298 * do_lo_send_direct_write - helper for writing data to a loop device
300 * This is the fast, non-transforming version for backing filesystems which do
301 * not implement the address space operations write_begin and write_end.
302 * It uses the write file operation which should be present on all writeable
305 static int do_lo_send_direct_write(struct loop_device
*lo
,
306 struct bio_vec
*bvec
, loff_t pos
, struct page
*page
)
308 ssize_t bw
= __do_lo_send_write(lo
->lo_backing_file
,
309 kmap(bvec
->bv_page
) + bvec
->bv_offset
,
311 kunmap(bvec
->bv_page
);
317 * do_lo_send_write - helper for writing data to a loop device
319 * This is the slow, transforming version for filesystems which do not
320 * implement the address space operations write_begin and write_end. It
321 * uses the write file operation which should be present on all writeable
324 * Using fops->write is slower than using aops->{prepare,commit}_write in the
325 * transforming case because we need to double buffer the data as we cannot do
326 * the transformations in place as we do not have direct access to the
327 * destination pages of the backing file.
329 static int do_lo_send_write(struct loop_device
*lo
, struct bio_vec
*bvec
,
330 loff_t pos
, struct page
*page
)
332 int ret
= lo_do_transfer(lo
, WRITE
, page
, 0, bvec
->bv_page
,
333 bvec
->bv_offset
, bvec
->bv_len
, pos
>> 9);
335 return __do_lo_send_write(lo
->lo_backing_file
,
336 page_address(page
), bvec
->bv_len
,
338 printk(KERN_ERR
"loop: Transfer error at byte offset %llu, "
339 "length %i.\n", (unsigned long long)pos
, bvec
->bv_len
);
345 static int lo_send(struct loop_device
*lo
, struct bio
*bio
, loff_t pos
)
347 int (*do_lo_send
)(struct loop_device
*, struct bio_vec
*, loff_t
,
349 struct bio_vec
*bvec
;
350 struct page
*page
= NULL
;
353 do_lo_send
= do_lo_send_aops
;
354 if (!(lo
->lo_flags
& LO_FLAGS_USE_AOPS
)) {
355 do_lo_send
= do_lo_send_direct_write
;
356 if (lo
->transfer
!= transfer_none
) {
357 page
= alloc_page(GFP_NOIO
| __GFP_HIGHMEM
);
361 do_lo_send
= do_lo_send_write
;
364 bio_for_each_segment(bvec
, bio
, i
) {
365 ret
= do_lo_send(lo
, bvec
, pos
, page
);
377 printk(KERN_ERR
"loop: Failed to allocate temporary page for write.\n");
382 struct lo_read_data
{
383 struct loop_device
*lo
;
390 lo_splice_actor(struct pipe_inode_info
*pipe
, struct pipe_buffer
*buf
,
391 struct splice_desc
*sd
)
393 struct lo_read_data
*p
= sd
->u
.data
;
394 struct loop_device
*lo
= p
->lo
;
395 struct page
*page
= buf
->page
;
399 IV
= ((sector_t
) page
->index
<< (PAGE_CACHE_SHIFT
- 9)) +
405 if (lo_do_transfer(lo
, READ
, page
, buf
->offset
, p
->page
, p
->offset
, size
, IV
)) {
406 printk(KERN_ERR
"loop: transfer error block %ld\n",
411 flush_dcache_page(p
->page
);
420 lo_direct_splice_actor(struct pipe_inode_info
*pipe
, struct splice_desc
*sd
)
422 return __splice_from_pipe(pipe
, sd
, lo_splice_actor
);
426 do_lo_receive(struct loop_device
*lo
,
427 struct bio_vec
*bvec
, int bsize
, loff_t pos
)
429 struct lo_read_data cookie
;
430 struct splice_desc sd
;
435 cookie
.page
= bvec
->bv_page
;
436 cookie
.offset
= bvec
->bv_offset
;
437 cookie
.bsize
= bsize
;
440 sd
.total_len
= bvec
->bv_len
;
445 file
= lo
->lo_backing_file
;
446 retval
= splice_direct_to_actor(file
, &sd
, lo_direct_splice_actor
);
455 lo_receive(struct loop_device
*lo
, struct bio
*bio
, int bsize
, loff_t pos
)
457 struct bio_vec
*bvec
;
460 bio_for_each_segment(bvec
, bio
, i
) {
461 ret
= do_lo_receive(lo
, bvec
, bsize
, pos
);
469 static int do_bio_filebacked(struct loop_device
*lo
, struct bio
*bio
)
474 pos
= ((loff_t
) bio
->bi_sector
<< 9) + lo
->lo_offset
;
476 if (bio_rw(bio
) == WRITE
) {
477 struct file
*file
= lo
->lo_backing_file
;
479 if (bio
->bi_rw
& REQ_FLUSH
) {
480 ret
= vfs_fsync(file
, 0);
481 if (unlikely(ret
&& ret
!= -EINVAL
)) {
487 ret
= lo_send(lo
, bio
, pos
);
489 if ((bio
->bi_rw
& REQ_FUA
) && !ret
) {
490 ret
= vfs_fsync(file
, 0);
491 if (unlikely(ret
&& ret
!= -EINVAL
))
495 ret
= lo_receive(lo
, bio
, lo
->lo_blocksize
, pos
);
502 * Add bio to back of pending list
504 static void loop_add_bio(struct loop_device
*lo
, struct bio
*bio
)
506 bio_list_add(&lo
->lo_bio_list
, bio
);
510 * Grab first pending buffer
512 static struct bio
*loop_get_bio(struct loop_device
*lo
)
514 return bio_list_pop(&lo
->lo_bio_list
);
517 static int loop_make_request(struct request_queue
*q
, struct bio
*old_bio
)
519 struct loop_device
*lo
= q
->queuedata
;
520 int rw
= bio_rw(old_bio
);
525 BUG_ON(!lo
|| (rw
!= READ
&& rw
!= WRITE
));
527 spin_lock_irq(&lo
->lo_lock
);
528 if (lo
->lo_state
!= Lo_bound
)
530 if (unlikely(rw
== WRITE
&& (lo
->lo_flags
& LO_FLAGS_READ_ONLY
)))
532 loop_add_bio(lo
, old_bio
);
533 wake_up(&lo
->lo_event
);
534 spin_unlock_irq(&lo
->lo_lock
);
538 spin_unlock_irq(&lo
->lo_lock
);
539 bio_io_error(old_bio
);
543 struct switch_request
{
545 struct completion wait
;
548 static void do_loop_switch(struct loop_device
*, struct switch_request
*);
550 static inline void loop_handle_bio(struct loop_device
*lo
, struct bio
*bio
)
552 if (unlikely(!bio
->bi_bdev
)) {
553 do_loop_switch(lo
, bio
->bi_private
);
556 int ret
= do_bio_filebacked(lo
, bio
);
562 * worker thread that handles reads/writes to file backed loop devices,
563 * to avoid blocking in our make_request_fn. it also does loop decrypting
564 * on reads for block backed loop, as that is too heavy to do from
565 * b_end_io context where irqs may be disabled.
567 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
568 * calling kthread_stop(). Therefore once kthread_should_stop() is
569 * true, make_request will not place any more requests. Therefore
570 * once kthread_should_stop() is true and lo_bio is NULL, we are
571 * done with the loop.
573 static int loop_thread(void *data
)
575 struct loop_device
*lo
= data
;
578 set_user_nice(current
, -20);
580 while (!kthread_should_stop() || !bio_list_empty(&lo
->lo_bio_list
)) {
582 wait_event_interruptible(lo
->lo_event
,
583 !bio_list_empty(&lo
->lo_bio_list
) ||
584 kthread_should_stop());
586 if (bio_list_empty(&lo
->lo_bio_list
))
588 spin_lock_irq(&lo
->lo_lock
);
589 bio
= loop_get_bio(lo
);
590 spin_unlock_irq(&lo
->lo_lock
);
593 loop_handle_bio(lo
, bio
);
600 * loop_switch performs the hard work of switching a backing store.
601 * First it needs to flush existing IO, it does this by sending a magic
602 * BIO down the pipe. The completion of this BIO does the actual switch.
604 static int loop_switch(struct loop_device
*lo
, struct file
*file
)
606 struct switch_request w
;
607 struct bio
*bio
= bio_alloc(GFP_KERNEL
, 0);
610 init_completion(&w
.wait
);
612 bio
->bi_private
= &w
;
614 loop_make_request(lo
->lo_queue
, bio
);
615 wait_for_completion(&w
.wait
);
620 * Helper to flush the IOs in loop, but keeping loop thread running
622 static int loop_flush(struct loop_device
*lo
)
624 /* loop not yet configured, no running thread, nothing to flush */
628 return loop_switch(lo
, NULL
);
632 * Do the actual switch; called from the BIO completion routine
634 static void do_loop_switch(struct loop_device
*lo
, struct switch_request
*p
)
636 struct file
*file
= p
->file
;
637 struct file
*old_file
= lo
->lo_backing_file
;
638 struct address_space
*mapping
;
640 /* if no new file, only flush of queued bios requested */
644 mapping
= file
->f_mapping
;
645 mapping_set_gfp_mask(old_file
->f_mapping
, lo
->old_gfp_mask
);
646 lo
->lo_backing_file
= file
;
647 lo
->lo_blocksize
= S_ISBLK(mapping
->host
->i_mode
) ?
648 mapping
->host
->i_bdev
->bd_block_size
: PAGE_SIZE
;
649 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
650 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
657 * loop_change_fd switched the backing store of a loopback device to
658 * a new file. This is useful for operating system installers to free up
659 * the original file and in High Availability environments to switch to
660 * an alternative location for the content in case of server meltdown.
661 * This can only work if the loop device is used read-only, and if the
662 * new backing store is the same size and type as the old backing store.
664 static int loop_change_fd(struct loop_device
*lo
, struct block_device
*bdev
,
667 struct file
*file
, *old_file
;
672 if (lo
->lo_state
!= Lo_bound
)
675 /* the loop device has to be read-only */
677 if (!(lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
685 inode
= file
->f_mapping
->host
;
686 old_file
= lo
->lo_backing_file
;
690 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
693 /* size of the new backing store needs to be the same */
694 if (get_loop_size(lo
, file
) != get_loop_size(lo
, old_file
))
698 error
= loop_switch(lo
, file
);
704 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
713 static inline int is_loop_device(struct file
*file
)
715 struct inode
*i
= file
->f_mapping
->host
;
717 return i
&& S_ISBLK(i
->i_mode
) && MAJOR(i
->i_rdev
) == LOOP_MAJOR
;
720 /* loop sysfs attributes */
722 static ssize_t
loop_attr_show(struct device
*dev
, char *page
,
723 ssize_t (*callback
)(struct loop_device
*, char *))
725 struct loop_device
*l
, *lo
= NULL
;
727 mutex_lock(&loop_devices_mutex
);
728 list_for_each_entry(l
, &loop_devices
, lo_list
)
729 if (disk_to_dev(l
->lo_disk
) == dev
) {
733 mutex_unlock(&loop_devices_mutex
);
735 return lo
? callback(lo
, page
) : -EIO
;
738 #define LOOP_ATTR_RO(_name) \
739 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
740 static ssize_t loop_attr_do_show_##_name(struct device *d, \
741 struct device_attribute *attr, char *b) \
743 return loop_attr_show(d, b, loop_attr_##_name##_show); \
745 static struct device_attribute loop_attr_##_name = \
746 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
748 static ssize_t
loop_attr_backing_file_show(struct loop_device
*lo
, char *buf
)
753 mutex_lock(&lo
->lo_ctl_mutex
);
754 if (lo
->lo_backing_file
)
755 p
= d_path(&lo
->lo_backing_file
->f_path
, buf
, PAGE_SIZE
- 1);
756 mutex_unlock(&lo
->lo_ctl_mutex
);
758 if (IS_ERR_OR_NULL(p
))
762 memmove(buf
, p
, ret
);
770 static ssize_t
loop_attr_offset_show(struct loop_device
*lo
, char *buf
)
772 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_offset
);
775 static ssize_t
loop_attr_sizelimit_show(struct loop_device
*lo
, char *buf
)
777 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_sizelimit
);
780 static ssize_t
loop_attr_autoclear_show(struct loop_device
*lo
, char *buf
)
782 int autoclear
= (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
);
784 return sprintf(buf
, "%s\n", autoclear
? "1" : "0");
787 LOOP_ATTR_RO(backing_file
);
788 LOOP_ATTR_RO(offset
);
789 LOOP_ATTR_RO(sizelimit
);
790 LOOP_ATTR_RO(autoclear
);
792 static struct attribute
*loop_attrs
[] = {
793 &loop_attr_backing_file
.attr
,
794 &loop_attr_offset
.attr
,
795 &loop_attr_sizelimit
.attr
,
796 &loop_attr_autoclear
.attr
,
800 static struct attribute_group loop_attribute_group
= {
805 static int loop_sysfs_init(struct loop_device
*lo
)
807 return sysfs_create_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
808 &loop_attribute_group
);
811 static void loop_sysfs_exit(struct loop_device
*lo
)
813 sysfs_remove_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
814 &loop_attribute_group
);
817 static int loop_set_fd(struct loop_device
*lo
, fmode_t mode
,
818 struct block_device
*bdev
, unsigned int arg
)
820 struct file
*file
, *f
;
822 struct address_space
*mapping
;
823 unsigned lo_blocksize
;
828 /* This is safe, since we have a reference from open(). */
829 __module_get(THIS_MODULE
);
837 if (lo
->lo_state
!= Lo_unbound
)
840 /* Avoid recursion */
842 while (is_loop_device(f
)) {
843 struct loop_device
*l
;
845 if (f
->f_mapping
->host
->i_bdev
== bdev
)
848 l
= f
->f_mapping
->host
->i_bdev
->bd_disk
->private_data
;
849 if (l
->lo_state
== Lo_unbound
) {
853 f
= l
->lo_backing_file
;
856 mapping
= file
->f_mapping
;
857 inode
= mapping
->host
;
859 if (!(file
->f_mode
& FMODE_WRITE
))
860 lo_flags
|= LO_FLAGS_READ_ONLY
;
863 if (S_ISREG(inode
->i_mode
) || S_ISBLK(inode
->i_mode
)) {
864 const struct address_space_operations
*aops
= mapping
->a_ops
;
866 if (aops
->write_begin
)
867 lo_flags
|= LO_FLAGS_USE_AOPS
;
868 if (!(lo_flags
& LO_FLAGS_USE_AOPS
) && !file
->f_op
->write
)
869 lo_flags
|= LO_FLAGS_READ_ONLY
;
871 lo_blocksize
= S_ISBLK(inode
->i_mode
) ?
872 inode
->i_bdev
->bd_block_size
: PAGE_SIZE
;
879 size
= get_loop_size(lo
, file
);
881 if ((loff_t
)(sector_t
)size
!= size
) {
886 if (!(mode
& FMODE_WRITE
))
887 lo_flags
|= LO_FLAGS_READ_ONLY
;
889 set_device_ro(bdev
, (lo_flags
& LO_FLAGS_READ_ONLY
) != 0);
891 lo
->lo_blocksize
= lo_blocksize
;
892 lo
->lo_device
= bdev
;
893 lo
->lo_flags
= lo_flags
;
894 lo
->lo_backing_file
= file
;
895 lo
->transfer
= transfer_none
;
897 lo
->lo_sizelimit
= 0;
898 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
899 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
901 bio_list_init(&lo
->lo_bio_list
);
904 * set queue make_request_fn, and add limits based on lower level
907 blk_queue_make_request(lo
->lo_queue
, loop_make_request
);
908 lo
->lo_queue
->queuedata
= lo
;
910 if (!(lo_flags
& LO_FLAGS_READ_ONLY
) && file
->f_op
->fsync
)
911 blk_queue_flush(lo
->lo_queue
, REQ_FLUSH
);
913 set_capacity(lo
->lo_disk
, size
);
914 bd_set_size(bdev
, size
<< 9);
916 /* let user-space know about the new size */
917 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
919 set_blocksize(bdev
, lo_blocksize
);
921 lo
->lo_thread
= kthread_create(loop_thread
, lo
, "loop%d",
923 if (IS_ERR(lo
->lo_thread
)) {
924 error
= PTR_ERR(lo
->lo_thread
);
927 lo
->lo_state
= Lo_bound
;
928 wake_up_process(lo
->lo_thread
);
930 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
935 lo
->lo_thread
= NULL
;
936 lo
->lo_device
= NULL
;
937 lo
->lo_backing_file
= NULL
;
939 set_capacity(lo
->lo_disk
, 0);
940 invalidate_bdev(bdev
);
941 bd_set_size(bdev
, 0);
942 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
943 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
);
944 lo
->lo_state
= Lo_unbound
;
948 /* This is safe: open() is still holding a reference. */
949 module_put(THIS_MODULE
);
954 loop_release_xfer(struct loop_device
*lo
)
957 struct loop_func_table
*xfer
= lo
->lo_encryption
;
961 err
= xfer
->release(lo
);
963 lo
->lo_encryption
= NULL
;
964 module_put(xfer
->owner
);
970 loop_init_xfer(struct loop_device
*lo
, struct loop_func_table
*xfer
,
971 const struct loop_info64
*i
)
976 struct module
*owner
= xfer
->owner
;
978 if (!try_module_get(owner
))
981 err
= xfer
->init(lo
, i
);
985 lo
->lo_encryption
= xfer
;
990 static int loop_clr_fd(struct loop_device
*lo
, struct block_device
*bdev
)
992 struct file
*filp
= lo
->lo_backing_file
;
993 gfp_t gfp
= lo
->old_gfp_mask
;
995 if (lo
->lo_state
!= Lo_bound
)
998 if (lo
->lo_refcnt
> 1) /* we needed one fd for the ioctl */
1004 spin_lock_irq(&lo
->lo_lock
);
1005 lo
->lo_state
= Lo_rundown
;
1006 spin_unlock_irq(&lo
->lo_lock
);
1008 kthread_stop(lo
->lo_thread
);
1010 lo
->lo_backing_file
= NULL
;
1012 loop_release_xfer(lo
);
1013 lo
->transfer
= NULL
;
1015 lo
->lo_device
= NULL
;
1016 lo
->lo_encryption
= NULL
;
1018 lo
->lo_sizelimit
= 0;
1019 lo
->lo_encrypt_key_size
= 0;
1021 lo
->lo_thread
= NULL
;
1022 memset(lo
->lo_encrypt_key
, 0, LO_KEY_SIZE
);
1023 memset(lo
->lo_crypt_name
, 0, LO_NAME_SIZE
);
1024 memset(lo
->lo_file_name
, 0, LO_NAME_SIZE
);
1026 invalidate_bdev(bdev
);
1027 set_capacity(lo
->lo_disk
, 0);
1028 loop_sysfs_exit(lo
);
1030 bd_set_size(bdev
, 0);
1031 /* let user-space know about this change */
1032 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1034 mapping_set_gfp_mask(filp
->f_mapping
, gfp
);
1035 lo
->lo_state
= Lo_unbound
;
1036 /* This is safe: open() is still holding a reference. */
1037 module_put(THIS_MODULE
);
1038 if (max_part
> 0 && bdev
)
1039 ioctl_by_bdev(bdev
, BLKRRPART
, 0);
1040 mutex_unlock(&lo
->lo_ctl_mutex
);
1042 * Need not hold lo_ctl_mutex to fput backing file.
1043 * Calling fput holding lo_ctl_mutex triggers a circular
1044 * lock dependency possibility warning as fput can take
1045 * bd_mutex which is usually taken before lo_ctl_mutex.
1052 loop_set_status(struct loop_device
*lo
, const struct loop_info64
*info
)
1055 struct loop_func_table
*xfer
;
1056 uid_t uid
= current_uid();
1058 if (lo
->lo_encrypt_key_size
&&
1059 lo
->lo_key_owner
!= uid
&&
1060 !capable(CAP_SYS_ADMIN
))
1062 if (lo
->lo_state
!= Lo_bound
)
1064 if ((unsigned int) info
->lo_encrypt_key_size
> LO_KEY_SIZE
)
1067 err
= loop_release_xfer(lo
);
1071 if (info
->lo_encrypt_type
) {
1072 unsigned int type
= info
->lo_encrypt_type
;
1074 if (type
>= MAX_LO_CRYPT
)
1076 xfer
= xfer_funcs
[type
];
1082 err
= loop_init_xfer(lo
, xfer
, info
);
1086 if (lo
->lo_offset
!= info
->lo_offset
||
1087 lo
->lo_sizelimit
!= info
->lo_sizelimit
) {
1088 lo
->lo_offset
= info
->lo_offset
;
1089 lo
->lo_sizelimit
= info
->lo_sizelimit
;
1090 if (figure_loop_size(lo
))
1094 memcpy(lo
->lo_file_name
, info
->lo_file_name
, LO_NAME_SIZE
);
1095 memcpy(lo
->lo_crypt_name
, info
->lo_crypt_name
, LO_NAME_SIZE
);
1096 lo
->lo_file_name
[LO_NAME_SIZE
-1] = 0;
1097 lo
->lo_crypt_name
[LO_NAME_SIZE
-1] = 0;
1101 lo
->transfer
= xfer
->transfer
;
1102 lo
->ioctl
= xfer
->ioctl
;
1104 if ((lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) !=
1105 (info
->lo_flags
& LO_FLAGS_AUTOCLEAR
))
1106 lo
->lo_flags
^= LO_FLAGS_AUTOCLEAR
;
1108 lo
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1109 lo
->lo_init
[0] = info
->lo_init
[0];
1110 lo
->lo_init
[1] = info
->lo_init
[1];
1111 if (info
->lo_encrypt_key_size
) {
1112 memcpy(lo
->lo_encrypt_key
, info
->lo_encrypt_key
,
1113 info
->lo_encrypt_key_size
);
1114 lo
->lo_key_owner
= uid
;
1121 loop_get_status(struct loop_device
*lo
, struct loop_info64
*info
)
1123 struct file
*file
= lo
->lo_backing_file
;
1127 if (lo
->lo_state
!= Lo_bound
)
1129 error
= vfs_getattr(file
->f_path
.mnt
, file
->f_path
.dentry
, &stat
);
1132 memset(info
, 0, sizeof(*info
));
1133 info
->lo_number
= lo
->lo_number
;
1134 info
->lo_device
= huge_encode_dev(stat
.dev
);
1135 info
->lo_inode
= stat
.ino
;
1136 info
->lo_rdevice
= huge_encode_dev(lo
->lo_device
? stat
.rdev
: stat
.dev
);
1137 info
->lo_offset
= lo
->lo_offset
;
1138 info
->lo_sizelimit
= lo
->lo_sizelimit
;
1139 info
->lo_flags
= lo
->lo_flags
;
1140 memcpy(info
->lo_file_name
, lo
->lo_file_name
, LO_NAME_SIZE
);
1141 memcpy(info
->lo_crypt_name
, lo
->lo_crypt_name
, LO_NAME_SIZE
);
1142 info
->lo_encrypt_type
=
1143 lo
->lo_encryption
? lo
->lo_encryption
->number
: 0;
1144 if (lo
->lo_encrypt_key_size
&& capable(CAP_SYS_ADMIN
)) {
1145 info
->lo_encrypt_key_size
= lo
->lo_encrypt_key_size
;
1146 memcpy(info
->lo_encrypt_key
, lo
->lo_encrypt_key
,
1147 lo
->lo_encrypt_key_size
);
1153 loop_info64_from_old(const struct loop_info
*info
, struct loop_info64
*info64
)
1155 memset(info64
, 0, sizeof(*info64
));
1156 info64
->lo_number
= info
->lo_number
;
1157 info64
->lo_device
= info
->lo_device
;
1158 info64
->lo_inode
= info
->lo_inode
;
1159 info64
->lo_rdevice
= info
->lo_rdevice
;
1160 info64
->lo_offset
= info
->lo_offset
;
1161 info64
->lo_sizelimit
= 0;
1162 info64
->lo_encrypt_type
= info
->lo_encrypt_type
;
1163 info64
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1164 info64
->lo_flags
= info
->lo_flags
;
1165 info64
->lo_init
[0] = info
->lo_init
[0];
1166 info64
->lo_init
[1] = info
->lo_init
[1];
1167 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1168 memcpy(info64
->lo_crypt_name
, info
->lo_name
, LO_NAME_SIZE
);
1170 memcpy(info64
->lo_file_name
, info
->lo_name
, LO_NAME_SIZE
);
1171 memcpy(info64
->lo_encrypt_key
, info
->lo_encrypt_key
, LO_KEY_SIZE
);
1175 loop_info64_to_old(const struct loop_info64
*info64
, struct loop_info
*info
)
1177 memset(info
, 0, sizeof(*info
));
1178 info
->lo_number
= info64
->lo_number
;
1179 info
->lo_device
= info64
->lo_device
;
1180 info
->lo_inode
= info64
->lo_inode
;
1181 info
->lo_rdevice
= info64
->lo_rdevice
;
1182 info
->lo_offset
= info64
->lo_offset
;
1183 info
->lo_encrypt_type
= info64
->lo_encrypt_type
;
1184 info
->lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1185 info
->lo_flags
= info64
->lo_flags
;
1186 info
->lo_init
[0] = info64
->lo_init
[0];
1187 info
->lo_init
[1] = info64
->lo_init
[1];
1188 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1189 memcpy(info
->lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1191 memcpy(info
->lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1192 memcpy(info
->lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1194 /* error in case values were truncated */
1195 if (info
->lo_device
!= info64
->lo_device
||
1196 info
->lo_rdevice
!= info64
->lo_rdevice
||
1197 info
->lo_inode
!= info64
->lo_inode
||
1198 info
->lo_offset
!= info64
->lo_offset
)
1205 loop_set_status_old(struct loop_device
*lo
, const struct loop_info __user
*arg
)
1207 struct loop_info info
;
1208 struct loop_info64 info64
;
1210 if (copy_from_user(&info
, arg
, sizeof (struct loop_info
)))
1212 loop_info64_from_old(&info
, &info64
);
1213 return loop_set_status(lo
, &info64
);
1217 loop_set_status64(struct loop_device
*lo
, const struct loop_info64 __user
*arg
)
1219 struct loop_info64 info64
;
1221 if (copy_from_user(&info64
, arg
, sizeof (struct loop_info64
)))
1223 return loop_set_status(lo
, &info64
);
1227 loop_get_status_old(struct loop_device
*lo
, struct loop_info __user
*arg
) {
1228 struct loop_info info
;
1229 struct loop_info64 info64
;
1235 err
= loop_get_status(lo
, &info64
);
1237 err
= loop_info64_to_old(&info64
, &info
);
1238 if (!err
&& copy_to_user(arg
, &info
, sizeof(info
)))
1245 loop_get_status64(struct loop_device
*lo
, struct loop_info64 __user
*arg
) {
1246 struct loop_info64 info64
;
1252 err
= loop_get_status(lo
, &info64
);
1253 if (!err
&& copy_to_user(arg
, &info64
, sizeof(info64
)))
1259 static int loop_set_capacity(struct loop_device
*lo
, struct block_device
*bdev
)
1266 if (unlikely(lo
->lo_state
!= Lo_bound
))
1268 err
= figure_loop_size(lo
);
1271 sec
= get_capacity(lo
->lo_disk
);
1272 /* the width of sector_t may be narrow for bit-shift */
1275 mutex_lock(&bdev
->bd_mutex
);
1276 bd_set_size(bdev
, sz
);
1277 /* let user-space know about the new size */
1278 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1279 mutex_unlock(&bdev
->bd_mutex
);
1285 static int lo_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
;
1291 mutex_lock_nested(&lo
->lo_ctl_mutex
, 1);
1294 err
= loop_set_fd(lo
, mode
, bdev
, arg
);
1296 case LOOP_CHANGE_FD
:
1297 err
= loop_change_fd(lo
, bdev
, arg
);
1300 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1301 err
= loop_clr_fd(lo
, bdev
);
1305 case LOOP_SET_STATUS
:
1306 err
= loop_set_status_old(lo
, (struct loop_info __user
*) arg
);
1308 case LOOP_GET_STATUS
:
1309 err
= loop_get_status_old(lo
, (struct loop_info __user
*) arg
);
1311 case LOOP_SET_STATUS64
:
1312 err
= loop_set_status64(lo
, (struct loop_info64 __user
*) arg
);
1314 case LOOP_GET_STATUS64
:
1315 err
= loop_get_status64(lo
, (struct loop_info64 __user
*) arg
);
1317 case LOOP_SET_CAPACITY
:
1319 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1320 err
= loop_set_capacity(lo
, bdev
);
1323 err
= lo
->ioctl
? lo
->ioctl(lo
, cmd
, arg
) : -EINVAL
;
1325 mutex_unlock(&lo
->lo_ctl_mutex
);
1331 #ifdef CONFIG_COMPAT
1332 struct compat_loop_info
{
1333 compat_int_t lo_number
; /* ioctl r/o */
1334 compat_dev_t lo_device
; /* ioctl r/o */
1335 compat_ulong_t lo_inode
; /* ioctl r/o */
1336 compat_dev_t lo_rdevice
; /* ioctl r/o */
1337 compat_int_t lo_offset
;
1338 compat_int_t lo_encrypt_type
;
1339 compat_int_t lo_encrypt_key_size
; /* ioctl w/o */
1340 compat_int_t lo_flags
; /* ioctl r/o */
1341 char lo_name
[LO_NAME_SIZE
];
1342 unsigned char lo_encrypt_key
[LO_KEY_SIZE
]; /* ioctl w/o */
1343 compat_ulong_t lo_init
[2];
1348 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1349 * - noinlined to reduce stack space usage in main part of driver
1352 loop_info64_from_compat(const struct compat_loop_info __user
*arg
,
1353 struct loop_info64
*info64
)
1355 struct compat_loop_info info
;
1357 if (copy_from_user(&info
, arg
, sizeof(info
)))
1360 memset(info64
, 0, sizeof(*info64
));
1361 info64
->lo_number
= info
.lo_number
;
1362 info64
->lo_device
= info
.lo_device
;
1363 info64
->lo_inode
= info
.lo_inode
;
1364 info64
->lo_rdevice
= info
.lo_rdevice
;
1365 info64
->lo_offset
= info
.lo_offset
;
1366 info64
->lo_sizelimit
= 0;
1367 info64
->lo_encrypt_type
= info
.lo_encrypt_type
;
1368 info64
->lo_encrypt_key_size
= info
.lo_encrypt_key_size
;
1369 info64
->lo_flags
= info
.lo_flags
;
1370 info64
->lo_init
[0] = info
.lo_init
[0];
1371 info64
->lo_init
[1] = info
.lo_init
[1];
1372 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1373 memcpy(info64
->lo_crypt_name
, info
.lo_name
, LO_NAME_SIZE
);
1375 memcpy(info64
->lo_file_name
, info
.lo_name
, LO_NAME_SIZE
);
1376 memcpy(info64
->lo_encrypt_key
, info
.lo_encrypt_key
, LO_KEY_SIZE
);
1381 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1382 * - noinlined to reduce stack space usage in main part of driver
1385 loop_info64_to_compat(const struct loop_info64
*info64
,
1386 struct compat_loop_info __user
*arg
)
1388 struct compat_loop_info info
;
1390 memset(&info
, 0, sizeof(info
));
1391 info
.lo_number
= info64
->lo_number
;
1392 info
.lo_device
= info64
->lo_device
;
1393 info
.lo_inode
= info64
->lo_inode
;
1394 info
.lo_rdevice
= info64
->lo_rdevice
;
1395 info
.lo_offset
= info64
->lo_offset
;
1396 info
.lo_encrypt_type
= info64
->lo_encrypt_type
;
1397 info
.lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1398 info
.lo_flags
= info64
->lo_flags
;
1399 info
.lo_init
[0] = info64
->lo_init
[0];
1400 info
.lo_init
[1] = info64
->lo_init
[1];
1401 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1402 memcpy(info
.lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1404 memcpy(info
.lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1405 memcpy(info
.lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1407 /* error in case values were truncated */
1408 if (info
.lo_device
!= info64
->lo_device
||
1409 info
.lo_rdevice
!= info64
->lo_rdevice
||
1410 info
.lo_inode
!= info64
->lo_inode
||
1411 info
.lo_offset
!= info64
->lo_offset
||
1412 info
.lo_init
[0] != info64
->lo_init
[0] ||
1413 info
.lo_init
[1] != info64
->lo_init
[1])
1416 if (copy_to_user(arg
, &info
, sizeof(info
)))
1422 loop_set_status_compat(struct loop_device
*lo
,
1423 const struct compat_loop_info __user
*arg
)
1425 struct loop_info64 info64
;
1428 ret
= loop_info64_from_compat(arg
, &info64
);
1431 return loop_set_status(lo
, &info64
);
1435 loop_get_status_compat(struct loop_device
*lo
,
1436 struct compat_loop_info __user
*arg
)
1438 struct loop_info64 info64
;
1444 err
= loop_get_status(lo
, &info64
);
1446 err
= loop_info64_to_compat(&info64
, arg
);
1450 static int lo_compat_ioctl(struct block_device
*bdev
, fmode_t mode
,
1451 unsigned int cmd
, unsigned long arg
)
1453 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1457 case LOOP_SET_STATUS
:
1458 mutex_lock(&lo
->lo_ctl_mutex
);
1459 err
= loop_set_status_compat(
1460 lo
, (const struct compat_loop_info __user
*) arg
);
1461 mutex_unlock(&lo
->lo_ctl_mutex
);
1463 case LOOP_GET_STATUS
:
1464 mutex_lock(&lo
->lo_ctl_mutex
);
1465 err
= loop_get_status_compat(
1466 lo
, (struct compat_loop_info __user
*) arg
);
1467 mutex_unlock(&lo
->lo_ctl_mutex
);
1469 case LOOP_SET_CAPACITY
:
1471 case LOOP_GET_STATUS64
:
1472 case LOOP_SET_STATUS64
:
1473 arg
= (unsigned long) compat_ptr(arg
);
1475 case LOOP_CHANGE_FD
:
1476 err
= lo_ioctl(bdev
, mode
, cmd
, arg
);
1486 static int lo_open(struct block_device
*bdev
, fmode_t mode
)
1488 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1490 mutex_lock(&lo
->lo_ctl_mutex
);
1492 mutex_unlock(&lo
->lo_ctl_mutex
);
1497 static int lo_release(struct gendisk
*disk
, fmode_t mode
)
1499 struct loop_device
*lo
= disk
->private_data
;
1502 mutex_lock(&lo
->lo_ctl_mutex
);
1504 if (--lo
->lo_refcnt
)
1507 if (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) {
1509 * In autoclear mode, stop the loop thread
1510 * and remove configuration after last close.
1512 err
= loop_clr_fd(lo
, NULL
);
1517 * Otherwise keep thread (if running) and config,
1518 * but flush possible ongoing bios in thread.
1524 mutex_unlock(&lo
->lo_ctl_mutex
);
1529 static const struct block_device_operations lo_fops
= {
1530 .owner
= THIS_MODULE
,
1532 .release
= lo_release
,
1534 #ifdef CONFIG_COMPAT
1535 .compat_ioctl
= lo_compat_ioctl
,
1540 * And now the modules code and kernel interface.
1542 static int max_loop
;
1543 module_param(max_loop
, int, S_IRUGO
);
1544 MODULE_PARM_DESC(max_loop
, "Maximum number of loop devices");
1545 module_param(max_part
, int, S_IRUGO
);
1546 MODULE_PARM_DESC(max_part
, "Maximum number of partitions per loop device");
1547 MODULE_LICENSE("GPL");
1548 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR
);
1550 int loop_register_transfer(struct loop_func_table
*funcs
)
1552 unsigned int n
= funcs
->number
;
1554 if (n
>= MAX_LO_CRYPT
|| xfer_funcs
[n
])
1556 xfer_funcs
[n
] = funcs
;
1560 int loop_unregister_transfer(int number
)
1562 unsigned int n
= number
;
1563 struct loop_device
*lo
;
1564 struct loop_func_table
*xfer
;
1566 if (n
== 0 || n
>= MAX_LO_CRYPT
|| (xfer
= xfer_funcs
[n
]) == NULL
)
1569 xfer_funcs
[n
] = NULL
;
1571 list_for_each_entry(lo
, &loop_devices
, lo_list
) {
1572 mutex_lock(&lo
->lo_ctl_mutex
);
1574 if (lo
->lo_encryption
== xfer
)
1575 loop_release_xfer(lo
);
1577 mutex_unlock(&lo
->lo_ctl_mutex
);
1583 EXPORT_SYMBOL(loop_register_transfer
);
1584 EXPORT_SYMBOL(loop_unregister_transfer
);
1586 static struct loop_device
*loop_alloc(int i
)
1588 struct loop_device
*lo
;
1589 struct gendisk
*disk
;
1591 lo
= kzalloc(sizeof(*lo
), GFP_KERNEL
);
1595 lo
->lo_queue
= blk_alloc_queue(GFP_KERNEL
);
1599 disk
= lo
->lo_disk
= alloc_disk(1 << part_shift
);
1601 goto out_free_queue
;
1603 mutex_init(&lo
->lo_ctl_mutex
);
1605 lo
->lo_thread
= NULL
;
1606 init_waitqueue_head(&lo
->lo_event
);
1607 spin_lock_init(&lo
->lo_lock
);
1608 disk
->major
= LOOP_MAJOR
;
1609 disk
->first_minor
= i
<< part_shift
;
1610 disk
->fops
= &lo_fops
;
1611 disk
->private_data
= lo
;
1612 disk
->queue
= lo
->lo_queue
;
1613 sprintf(disk
->disk_name
, "loop%d", i
);
1617 blk_cleanup_queue(lo
->lo_queue
);
1624 static void loop_free(struct loop_device
*lo
)
1626 blk_cleanup_queue(lo
->lo_queue
);
1627 put_disk(lo
->lo_disk
);
1628 list_del(&lo
->lo_list
);
1632 static struct loop_device
*loop_init_one(int i
)
1634 struct loop_device
*lo
;
1636 list_for_each_entry(lo
, &loop_devices
, lo_list
) {
1637 if (lo
->lo_number
== i
)
1643 add_disk(lo
->lo_disk
);
1644 list_add_tail(&lo
->lo_list
, &loop_devices
);
1649 static void loop_del_one(struct loop_device
*lo
)
1651 del_gendisk(lo
->lo_disk
);
1655 static struct kobject
*loop_probe(dev_t dev
, int *part
, void *data
)
1657 struct loop_device
*lo
;
1658 struct kobject
*kobj
;
1660 mutex_lock(&loop_devices_mutex
);
1661 lo
= loop_init_one(MINOR(dev
) >> part_shift
);
1662 kobj
= lo
? get_disk(lo
->lo_disk
) : ERR_PTR(-ENOMEM
);
1663 mutex_unlock(&loop_devices_mutex
);
1669 static int __init
loop_init(void)
1672 unsigned long range
;
1673 struct loop_device
*lo
, *next
;
1676 * loop module now has a feature to instantiate underlying device
1677 * structure on-demand, provided that there is an access dev node.
1678 * However, this will not work well with user space tool that doesn't
1679 * know about such "feature". In order to not break any existing
1680 * tool, we do the following:
1682 * (1) if max_loop is specified, create that many upfront, and this
1683 * also becomes a hard limit.
1684 * (2) if max_loop is not specified, create 8 loop device on module
1685 * load, user can further extend loop device by create dev node
1686 * themselves and have kernel automatically instantiate actual
1692 part_shift
= fls(max_part
);
1695 * Adjust max_part according to part_shift as it is exported
1696 * to user space so that user can decide correct minor number
1697 * if [s]he want to create more devices.
1699 * Note that -1 is required because partition 0 is reserved
1700 * for the whole disk.
1702 max_part
= (1UL << part_shift
) - 1;
1705 if ((1UL << part_shift
) > DISK_MAX_PARTS
)
1708 if (max_loop
> 1UL << (MINORBITS
- part_shift
))
1713 range
= max_loop
<< part_shift
;
1716 range
= 1UL << MINORBITS
;
1719 if (register_blkdev(LOOP_MAJOR
, "loop"))
1722 for (i
= 0; i
< nr
; i
++) {
1726 list_add_tail(&lo
->lo_list
, &loop_devices
);
1729 /* point of no return */
1731 list_for_each_entry(lo
, &loop_devices
, lo_list
)
1732 add_disk(lo
->lo_disk
);
1734 blk_register_region(MKDEV(LOOP_MAJOR
, 0), range
,
1735 THIS_MODULE
, loop_probe
, NULL
, NULL
);
1737 printk(KERN_INFO
"loop: module loaded\n");
1741 printk(KERN_INFO
"loop: out of memory\n");
1743 list_for_each_entry_safe(lo
, next
, &loop_devices
, lo_list
)
1746 unregister_blkdev(LOOP_MAJOR
, "loop");
1750 static void __exit
loop_exit(void)
1752 unsigned long range
;
1753 struct loop_device
*lo
, *next
;
1755 range
= max_loop
? max_loop
<< part_shift
: 1UL << MINORBITS
;
1757 list_for_each_entry_safe(lo
, next
, &loop_devices
, lo_list
)
1760 blk_unregister_region(MKDEV(LOOP_MAJOR
, 0), range
);
1761 unregister_blkdev(LOOP_MAJOR
, "loop");
1764 module_init(loop_init
);
1765 module_exit(loop_exit
);
1768 static int __init
max_loop_setup(char *str
)
1770 max_loop
= simple_strtol(str
, NULL
, 0);
1774 __setup("max_loop=", max_loop_setup
);