2 * linux/drivers/block/loop.c
4 * Written by Theodore Ts'o, 3/29/93
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
9 * DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
10 * more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
12 * Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
13 * Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
21 * Loadable modules and other fixes by AK, 1998
23 * Make real block number available to downstream transfer functions, enables
24 * CBC (and relatives) mode encryption requiring unique IVs per data block.
25 * Reed H. Petty, rhp@draper.net
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
30 * Maximum number of loop devices when compiled-in now selectable by passing
31 * max_loop=<1-255> to the kernel on boot.
32 * Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
34 * Completely rewrite request handling to be make_request_fn style and
35 * non blocking, pushing work to a helper thread. Lots of fixes from
37 * Jens Axboe <axboe@suse.de>, Nov 2000
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
42 * Support for falling back on the write file operation when the address space
43 * operations write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
52 #include <linux/module.h>
53 #include <linux/moduleparam.h>
54 #include <linux/sched.h>
56 #include <linux/file.h>
57 #include <linux/stat.h>
58 #include <linux/errno.h>
59 #include <linux/major.h>
60 #include <linux/wait.h>
61 #include <linux/blkdev.h>
62 #include <linux/blkpg.h>
63 #include <linux/init.h>
64 #include <linux/swap.h>
65 #include <linux/slab.h>
66 #include <linux/compat.h>
67 #include <linux/suspend.h>
68 #include <linux/freezer.h>
69 #include <linux/mutex.h>
70 #include <linux/writeback.h>
71 #include <linux/completion.h>
72 #include <linux/highmem.h>
73 #include <linux/kthread.h>
74 #include <linux/splice.h>
75 #include <linux/sysfs.h>
76 #include <linux/miscdevice.h>
77 #include <linux/falloc.h>
78 #include <linux/uio.h>
81 #include <asm/uaccess.h>
83 static DEFINE_IDR(loop_index_idr
);
84 static DEFINE_MUTEX(loop_index_mutex
);
87 static int part_shift
;
89 static int transfer_xor(struct loop_device
*lo
, int cmd
,
90 struct page
*raw_page
, unsigned raw_off
,
91 struct page
*loop_page
, unsigned loop_off
,
92 int size
, sector_t real_block
)
94 char *raw_buf
= kmap_atomic(raw_page
) + raw_off
;
95 char *loop_buf
= kmap_atomic(loop_page
) + loop_off
;
107 key
= lo
->lo_encrypt_key
;
108 keysize
= lo
->lo_encrypt_key_size
;
109 for (i
= 0; i
< size
; i
++)
110 *out
++ = *in
++ ^ key
[(i
& 511) % keysize
];
112 kunmap_atomic(loop_buf
);
113 kunmap_atomic(raw_buf
);
118 static int xor_init(struct loop_device
*lo
, const struct loop_info64
*info
)
120 if (unlikely(info
->lo_encrypt_key_size
<= 0))
125 static struct loop_func_table none_funcs
= {
126 .number
= LO_CRYPT_NONE
,
129 static struct loop_func_table xor_funcs
= {
130 .number
= LO_CRYPT_XOR
,
131 .transfer
= transfer_xor
,
135 /* xfer_funcs[0] is special - its release function is never called */
136 static struct loop_func_table
*xfer_funcs
[MAX_LO_CRYPT
] = {
141 static loff_t
get_size(loff_t offset
, loff_t sizelimit
, struct file
*file
)
145 /* Compute loopsize in bytes */
146 loopsize
= i_size_read(file
->f_mapping
->host
);
149 /* offset is beyond i_size, weird but possible */
153 if (sizelimit
> 0 && sizelimit
< loopsize
)
154 loopsize
= sizelimit
;
156 * Unfortunately, if we want to do I/O on the device,
157 * the number of 512-byte sectors has to fit into a sector_t.
159 return loopsize
>> 9;
162 static loff_t
get_loop_size(struct loop_device
*lo
, struct file
*file
)
164 return get_size(lo
->lo_offset
, lo
->lo_sizelimit
, file
);
167 static void __loop_update_dio(struct loop_device
*lo
, bool dio
)
169 struct file
*file
= lo
->lo_backing_file
;
170 struct address_space
*mapping
= file
->f_mapping
;
171 struct inode
*inode
= mapping
->host
;
172 unsigned short sb_bsize
= 0;
173 unsigned dio_align
= 0;
176 if (inode
->i_sb
->s_bdev
) {
177 sb_bsize
= bdev_logical_block_size(inode
->i_sb
->s_bdev
);
178 dio_align
= sb_bsize
- 1;
182 * We support direct I/O only if lo_offset is aligned with the
183 * logical I/O size of backing device, and the logical block
184 * size of loop is bigger than the backing device's and the loop
185 * needn't transform transfer.
187 * TODO: the above condition may be loosed in the future, and
188 * direct I/O may be switched runtime at that time because most
189 * of requests in sane appplications should be PAGE_SIZE algined
192 if (queue_logical_block_size(lo
->lo_queue
) >= sb_bsize
&&
193 !(lo
->lo_offset
& dio_align
) &&
194 mapping
->a_ops
->direct_IO
&&
203 if (lo
->use_dio
== use_dio
)
206 /* flush dirty pages before changing direct IO */
210 * The flag of LO_FLAGS_DIRECT_IO is handled similarly with
211 * LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
212 * will get updated by ioctl(LOOP_GET_STATUS)
214 blk_mq_freeze_queue(lo
->lo_queue
);
215 lo
->use_dio
= use_dio
;
217 lo
->lo_flags
|= LO_FLAGS_DIRECT_IO
;
219 lo
->lo_flags
&= ~LO_FLAGS_DIRECT_IO
;
220 blk_mq_unfreeze_queue(lo
->lo_queue
);
224 figure_loop_size(struct loop_device
*lo
, loff_t offset
, loff_t sizelimit
)
226 loff_t size
= get_size(offset
, sizelimit
, lo
->lo_backing_file
);
227 sector_t x
= (sector_t
)size
;
228 struct block_device
*bdev
= lo
->lo_device
;
230 if (unlikely((loff_t
)x
!= size
))
232 if (lo
->lo_offset
!= offset
)
233 lo
->lo_offset
= offset
;
234 if (lo
->lo_sizelimit
!= sizelimit
)
235 lo
->lo_sizelimit
= sizelimit
;
236 set_capacity(lo
->lo_disk
, x
);
237 bd_set_size(bdev
, (loff_t
)get_capacity(bdev
->bd_disk
) << 9);
238 /* let user-space know about the new size */
239 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
244 lo_do_transfer(struct loop_device
*lo
, int cmd
,
245 struct page
*rpage
, unsigned roffs
,
246 struct page
*lpage
, unsigned loffs
,
247 int size
, sector_t rblock
)
251 ret
= lo
->transfer(lo
, cmd
, rpage
, roffs
, lpage
, loffs
, size
, rblock
);
255 printk_ratelimited(KERN_ERR
256 "loop: Transfer error at byte offset %llu, length %i.\n",
257 (unsigned long long)rblock
<< 9, size
);
261 static int lo_write_bvec(struct file
*file
, struct bio_vec
*bvec
, loff_t
*ppos
)
266 iov_iter_bvec(&i
, ITER_BVEC
, bvec
, 1, bvec
->bv_len
);
268 file_start_write(file
);
269 bw
= vfs_iter_write(file
, &i
, ppos
);
270 file_end_write(file
);
272 if (likely(bw
== bvec
->bv_len
))
275 printk_ratelimited(KERN_ERR
276 "loop: Write error at byte offset %llu, length %i.\n",
277 (unsigned long long)*ppos
, bvec
->bv_len
);
283 static int lo_write_simple(struct loop_device
*lo
, struct request
*rq
,
287 struct req_iterator iter
;
290 rq_for_each_segment(bvec
, rq
, iter
) {
291 ret
= lo_write_bvec(lo
->lo_backing_file
, &bvec
, &pos
);
301 * This is the slow, transforming version that needs to double buffer the
302 * data as it cannot do the transformations in place without having direct
303 * access to the destination pages of the backing file.
305 static int lo_write_transfer(struct loop_device
*lo
, struct request
*rq
,
308 struct bio_vec bvec
, b
;
309 struct req_iterator iter
;
313 page
= alloc_page(GFP_NOIO
);
317 rq_for_each_segment(bvec
, rq
, iter
) {
318 ret
= lo_do_transfer(lo
, WRITE
, page
, 0, bvec
.bv_page
,
319 bvec
.bv_offset
, bvec
.bv_len
, pos
>> 9);
325 b
.bv_len
= bvec
.bv_len
;
326 ret
= lo_write_bvec(lo
->lo_backing_file
, &b
, &pos
);
335 static int lo_read_simple(struct loop_device
*lo
, struct request
*rq
,
339 struct req_iterator iter
;
343 rq_for_each_segment(bvec
, rq
, iter
) {
344 iov_iter_bvec(&i
, ITER_BVEC
, &bvec
, 1, bvec
.bv_len
);
345 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
349 flush_dcache_page(bvec
.bv_page
);
351 if (len
!= bvec
.bv_len
) {
354 __rq_for_each_bio(bio
, rq
)
364 static int lo_read_transfer(struct loop_device
*lo
, struct request
*rq
,
367 struct bio_vec bvec
, b
;
368 struct req_iterator iter
;
374 page
= alloc_page(GFP_NOIO
);
378 rq_for_each_segment(bvec
, rq
, iter
) {
383 b
.bv_len
= bvec
.bv_len
;
385 iov_iter_bvec(&i
, ITER_BVEC
, &b
, 1, b
.bv_len
);
386 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
392 ret
= lo_do_transfer(lo
, READ
, page
, 0, bvec
.bv_page
,
393 bvec
.bv_offset
, len
, offset
>> 9);
397 flush_dcache_page(bvec
.bv_page
);
399 if (len
!= bvec
.bv_len
) {
402 __rq_for_each_bio(bio
, rq
)
414 static int lo_discard(struct loop_device
*lo
, struct request
*rq
, loff_t pos
)
417 * We use punch hole to reclaim the free space used by the
418 * image a.k.a. discard. However we do not support discard if
419 * encryption is enabled, because it may give an attacker
420 * useful information.
422 struct file
*file
= lo
->lo_backing_file
;
423 int mode
= FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
;
426 if ((!file
->f_op
->fallocate
) || lo
->lo_encrypt_key_size
) {
431 ret
= file
->f_op
->fallocate(file
, mode
, pos
, blk_rq_bytes(rq
));
432 if (unlikely(ret
&& ret
!= -EINVAL
&& ret
!= -EOPNOTSUPP
))
438 static int lo_req_flush(struct loop_device
*lo
, struct request
*rq
)
440 struct file
*file
= lo
->lo_backing_file
;
441 int ret
= vfs_fsync(file
, 0);
442 if (unlikely(ret
&& ret
!= -EINVAL
))
448 static inline void handle_partial_read(struct loop_cmd
*cmd
, long bytes
)
450 if (bytes
< 0 || op_is_write(req_op(cmd
->rq
)))
453 if (unlikely(bytes
< blk_rq_bytes(cmd
->rq
))) {
454 struct bio
*bio
= cmd
->rq
->bio
;
456 bio_advance(bio
, bytes
);
461 static void lo_rw_aio_complete(struct kiocb
*iocb
, long ret
, long ret2
)
463 struct loop_cmd
*cmd
= container_of(iocb
, struct loop_cmd
, iocb
);
464 struct request
*rq
= cmd
->rq
;
466 handle_partial_read(cmd
, ret
);
473 blk_mq_complete_request(rq
, ret
);
476 static int lo_rw_aio(struct loop_device
*lo
, struct loop_cmd
*cmd
,
479 struct iov_iter iter
;
480 struct bio_vec
*bvec
;
481 struct bio
*bio
= cmd
->rq
->bio
;
482 struct file
*file
= lo
->lo_backing_file
;
485 /* nomerge for loop request queue */
486 WARN_ON(cmd
->rq
->bio
!= cmd
->rq
->biotail
);
488 bvec
= __bvec_iter_bvec(bio
->bi_io_vec
, bio
->bi_iter
);
489 iov_iter_bvec(&iter
, ITER_BVEC
| rw
, bvec
,
490 bio_segments(bio
), blk_rq_bytes(cmd
->rq
));
492 * This bio may be started from the middle of the 'bvec'
493 * because of bio splitting, so offset from the bvec must
494 * be passed to iov iterator
496 iter
.iov_offset
= bio
->bi_iter
.bi_bvec_done
;
498 cmd
->iocb
.ki_pos
= pos
;
499 cmd
->iocb
.ki_filp
= file
;
500 cmd
->iocb
.ki_complete
= lo_rw_aio_complete
;
501 cmd
->iocb
.ki_flags
= IOCB_DIRECT
;
504 ret
= file
->f_op
->write_iter(&cmd
->iocb
, &iter
);
506 ret
= file
->f_op
->read_iter(&cmd
->iocb
, &iter
);
508 if (ret
!= -EIOCBQUEUED
)
509 cmd
->iocb
.ki_complete(&cmd
->iocb
, ret
, 0);
513 static int do_req_filebacked(struct loop_device
*lo
, struct request
*rq
)
515 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
516 loff_t pos
= ((loff_t
) blk_rq_pos(rq
) << 9) + lo
->lo_offset
;
519 * lo_write_simple and lo_read_simple should have been covered
520 * by io submit style function like lo_rw_aio(), one blocker
521 * is that lo_read_simple() need to call flush_dcache_page after
522 * the page is written from kernel, and it isn't easy to handle
523 * this in io submit style function which submits all segments
524 * of the req at one time. And direct read IO doesn't need to
525 * run flush_dcache_page().
527 switch (req_op(rq
)) {
529 return lo_req_flush(lo
, rq
);
531 return lo_discard(lo
, rq
, pos
);
534 return lo_write_transfer(lo
, rq
, pos
);
535 else if (cmd
->use_aio
)
536 return lo_rw_aio(lo
, cmd
, pos
, WRITE
);
538 return lo_write_simple(lo
, rq
, pos
);
541 return lo_read_transfer(lo
, rq
, pos
);
542 else if (cmd
->use_aio
)
543 return lo_rw_aio(lo
, cmd
, pos
, READ
);
545 return lo_read_simple(lo
, rq
, pos
);
553 struct switch_request
{
555 struct completion wait
;
558 static inline void loop_update_dio(struct loop_device
*lo
)
560 __loop_update_dio(lo
, io_is_direct(lo
->lo_backing_file
) |
565 * Do the actual switch; called from the BIO completion routine
567 static void do_loop_switch(struct loop_device
*lo
, struct switch_request
*p
)
569 struct file
*file
= p
->file
;
570 struct file
*old_file
= lo
->lo_backing_file
;
571 struct address_space
*mapping
;
573 /* if no new file, only flush of queued bios requested */
577 mapping
= file
->f_mapping
;
578 mapping_set_gfp_mask(old_file
->f_mapping
, lo
->old_gfp_mask
);
579 lo
->lo_backing_file
= file
;
580 lo
->lo_blocksize
= S_ISBLK(mapping
->host
->i_mode
) ?
581 mapping
->host
->i_bdev
->bd_block_size
: PAGE_SIZE
;
582 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
583 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
588 * loop_switch performs the hard work of switching a backing store.
589 * First it needs to flush existing IO, it does this by sending a magic
590 * BIO down the pipe. The completion of this BIO does the actual switch.
592 static int loop_switch(struct loop_device
*lo
, struct file
*file
)
594 struct switch_request w
;
598 /* freeze queue and wait for completion of scheduled requests */
599 blk_mq_freeze_queue(lo
->lo_queue
);
601 /* do the switch action */
602 do_loop_switch(lo
, &w
);
605 blk_mq_unfreeze_queue(lo
->lo_queue
);
611 * Helper to flush the IOs in loop, but keeping loop thread running
613 static int loop_flush(struct loop_device
*lo
)
615 return loop_switch(lo
, NULL
);
618 static void loop_reread_partitions(struct loop_device
*lo
,
619 struct block_device
*bdev
)
624 * bd_mutex has been held already in release path, so don't
625 * acquire it if this function is called in such case.
627 * If the reread partition isn't from release path, lo_refcnt
628 * must be at least one and it can only become zero when the
629 * current holder is released.
631 if (!atomic_read(&lo
->lo_refcnt
))
632 rc
= __blkdev_reread_part(bdev
);
634 rc
= blkdev_reread_part(bdev
);
636 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
637 __func__
, lo
->lo_number
, lo
->lo_file_name
, rc
);
641 * loop_change_fd switched the backing store of a loopback device to
642 * a new file. This is useful for operating system installers to free up
643 * the original file and in High Availability environments to switch to
644 * an alternative location for the content in case of server meltdown.
645 * This can only work if the loop device is used read-only, and if the
646 * new backing store is the same size and type as the old backing store.
648 static int loop_change_fd(struct loop_device
*lo
, struct block_device
*bdev
,
651 struct file
*file
, *old_file
;
656 if (lo
->lo_state
!= Lo_bound
)
659 /* the loop device has to be read-only */
661 if (!(lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
669 inode
= file
->f_mapping
->host
;
670 old_file
= lo
->lo_backing_file
;
674 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
677 /* size of the new backing store needs to be the same */
678 if (get_loop_size(lo
, file
) != get_loop_size(lo
, old_file
))
682 error
= loop_switch(lo
, file
);
687 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
688 loop_reread_partitions(lo
, bdev
);
697 static inline int is_loop_device(struct file
*file
)
699 struct inode
*i
= file
->f_mapping
->host
;
701 return i
&& S_ISBLK(i
->i_mode
) && MAJOR(i
->i_rdev
) == LOOP_MAJOR
;
704 /* loop sysfs attributes */
706 static ssize_t
loop_attr_show(struct device
*dev
, char *page
,
707 ssize_t (*callback
)(struct loop_device
*, char *))
709 struct gendisk
*disk
= dev_to_disk(dev
);
710 struct loop_device
*lo
= disk
->private_data
;
712 return callback(lo
, page
);
715 #define LOOP_ATTR_RO(_name) \
716 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
717 static ssize_t loop_attr_do_show_##_name(struct device *d, \
718 struct device_attribute *attr, char *b) \
720 return loop_attr_show(d, b, loop_attr_##_name##_show); \
722 static struct device_attribute loop_attr_##_name = \
723 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
725 static ssize_t
loop_attr_backing_file_show(struct loop_device
*lo
, char *buf
)
730 spin_lock_irq(&lo
->lo_lock
);
731 if (lo
->lo_backing_file
)
732 p
= file_path(lo
->lo_backing_file
, buf
, PAGE_SIZE
- 1);
733 spin_unlock_irq(&lo
->lo_lock
);
735 if (IS_ERR_OR_NULL(p
))
739 memmove(buf
, p
, ret
);
747 static ssize_t
loop_attr_offset_show(struct loop_device
*lo
, char *buf
)
749 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_offset
);
752 static ssize_t
loop_attr_sizelimit_show(struct loop_device
*lo
, char *buf
)
754 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_sizelimit
);
757 static ssize_t
loop_attr_autoclear_show(struct loop_device
*lo
, char *buf
)
759 int autoclear
= (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
);
761 return sprintf(buf
, "%s\n", autoclear
? "1" : "0");
764 static ssize_t
loop_attr_partscan_show(struct loop_device
*lo
, char *buf
)
766 int partscan
= (lo
->lo_flags
& LO_FLAGS_PARTSCAN
);
768 return sprintf(buf
, "%s\n", partscan
? "1" : "0");
771 static ssize_t
loop_attr_dio_show(struct loop_device
*lo
, char *buf
)
773 int dio
= (lo
->lo_flags
& LO_FLAGS_DIRECT_IO
);
775 return sprintf(buf
, "%s\n", dio
? "1" : "0");
778 LOOP_ATTR_RO(backing_file
);
779 LOOP_ATTR_RO(offset
);
780 LOOP_ATTR_RO(sizelimit
);
781 LOOP_ATTR_RO(autoclear
);
782 LOOP_ATTR_RO(partscan
);
785 static struct attribute
*loop_attrs
[] = {
786 &loop_attr_backing_file
.attr
,
787 &loop_attr_offset
.attr
,
788 &loop_attr_sizelimit
.attr
,
789 &loop_attr_autoclear
.attr
,
790 &loop_attr_partscan
.attr
,
795 static struct attribute_group loop_attribute_group
= {
800 static int loop_sysfs_init(struct loop_device
*lo
)
802 return sysfs_create_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
803 &loop_attribute_group
);
806 static void loop_sysfs_exit(struct loop_device
*lo
)
808 sysfs_remove_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
809 &loop_attribute_group
);
812 static void loop_config_discard(struct loop_device
*lo
)
814 struct file
*file
= lo
->lo_backing_file
;
815 struct inode
*inode
= file
->f_mapping
->host
;
816 struct request_queue
*q
= lo
->lo_queue
;
819 * We use punch hole to reclaim the free space used by the
820 * image a.k.a. discard. However we do not support discard if
821 * encryption is enabled, because it may give an attacker
822 * useful information.
824 if ((!file
->f_op
->fallocate
) ||
825 lo
->lo_encrypt_key_size
) {
826 q
->limits
.discard_granularity
= 0;
827 q
->limits
.discard_alignment
= 0;
828 blk_queue_max_discard_sectors(q
, 0);
829 q
->limits
.discard_zeroes_data
= 0;
830 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD
, q
);
834 q
->limits
.discard_granularity
= inode
->i_sb
->s_blocksize
;
835 q
->limits
.discard_alignment
= 0;
836 blk_queue_max_discard_sectors(q
, UINT_MAX
>> 9);
837 q
->limits
.discard_zeroes_data
= 1;
838 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, q
);
841 static void loop_unprepare_queue(struct loop_device
*lo
)
843 kthread_flush_worker(&lo
->worker
);
844 kthread_stop(lo
->worker_task
);
847 static int loop_prepare_queue(struct loop_device
*lo
)
849 kthread_init_worker(&lo
->worker
);
850 lo
->worker_task
= kthread_run(kthread_worker_fn
,
851 &lo
->worker
, "loop%d", lo
->lo_number
);
852 if (IS_ERR(lo
->worker_task
))
854 set_user_nice(lo
->worker_task
, MIN_NICE
);
858 static int loop_set_fd(struct loop_device
*lo
, fmode_t mode
,
859 struct block_device
*bdev
, unsigned int arg
)
861 struct file
*file
, *f
;
863 struct address_space
*mapping
;
864 unsigned lo_blocksize
;
869 /* This is safe, since we have a reference from open(). */
870 __module_get(THIS_MODULE
);
878 if (lo
->lo_state
!= Lo_unbound
)
881 /* Avoid recursion */
883 while (is_loop_device(f
)) {
884 struct loop_device
*l
;
886 if (f
->f_mapping
->host
->i_bdev
== bdev
)
889 l
= f
->f_mapping
->host
->i_bdev
->bd_disk
->private_data
;
890 if (l
->lo_state
== Lo_unbound
) {
894 f
= l
->lo_backing_file
;
897 mapping
= file
->f_mapping
;
898 inode
= mapping
->host
;
901 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
904 if (!(file
->f_mode
& FMODE_WRITE
) || !(mode
& FMODE_WRITE
) ||
905 !file
->f_op
->write_iter
)
906 lo_flags
|= LO_FLAGS_READ_ONLY
;
908 lo_blocksize
= S_ISBLK(inode
->i_mode
) ?
909 inode
->i_bdev
->bd_block_size
: PAGE_SIZE
;
912 size
= get_loop_size(lo
, file
);
913 if ((loff_t
)(sector_t
)size
!= size
)
915 error
= loop_prepare_queue(lo
);
921 set_device_ro(bdev
, (lo_flags
& LO_FLAGS_READ_ONLY
) != 0);
924 lo
->lo_blocksize
= lo_blocksize
;
925 lo
->lo_device
= bdev
;
926 lo
->lo_flags
= lo_flags
;
927 lo
->lo_backing_file
= file
;
930 lo
->lo_sizelimit
= 0;
931 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
932 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
934 if (!(lo_flags
& LO_FLAGS_READ_ONLY
) && file
->f_op
->fsync
)
935 blk_queue_write_cache(lo
->lo_queue
, true, false);
938 set_capacity(lo
->lo_disk
, size
);
939 bd_set_size(bdev
, size
<< 9);
941 /* let user-space know about the new size */
942 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
944 set_blocksize(bdev
, lo_blocksize
);
946 lo
->lo_state
= Lo_bound
;
948 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
949 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
950 loop_reread_partitions(lo
, bdev
);
952 /* Grab the block_device to prevent its destruction after we
953 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
961 /* This is safe: open() is still holding a reference. */
962 module_put(THIS_MODULE
);
967 loop_release_xfer(struct loop_device
*lo
)
970 struct loop_func_table
*xfer
= lo
->lo_encryption
;
974 err
= xfer
->release(lo
);
976 lo
->lo_encryption
= NULL
;
977 module_put(xfer
->owner
);
983 loop_init_xfer(struct loop_device
*lo
, struct loop_func_table
*xfer
,
984 const struct loop_info64
*i
)
989 struct module
*owner
= xfer
->owner
;
991 if (!try_module_get(owner
))
994 err
= xfer
->init(lo
, i
);
998 lo
->lo_encryption
= xfer
;
1003 static int loop_clr_fd(struct loop_device
*lo
)
1005 struct file
*filp
= lo
->lo_backing_file
;
1006 gfp_t gfp
= lo
->old_gfp_mask
;
1007 struct block_device
*bdev
= lo
->lo_device
;
1009 if (lo
->lo_state
!= Lo_bound
)
1013 * If we've explicitly asked to tear down the loop device,
1014 * and it has an elevated reference count, set it for auto-teardown when
1015 * the last reference goes away. This stops $!~#$@ udev from
1016 * preventing teardown because it decided that it needs to run blkid on
1017 * the loopback device whenever they appear. xfstests is notorious for
1018 * failing tests because blkid via udev races with a losetup
1019 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1020 * command to fail with EBUSY.
1022 if (atomic_read(&lo
->lo_refcnt
) > 1) {
1023 lo
->lo_flags
|= LO_FLAGS_AUTOCLEAR
;
1024 mutex_unlock(&lo
->lo_ctl_mutex
);
1031 /* freeze request queue during the transition */
1032 blk_mq_freeze_queue(lo
->lo_queue
);
1034 spin_lock_irq(&lo
->lo_lock
);
1035 lo
->lo_state
= Lo_rundown
;
1036 lo
->lo_backing_file
= NULL
;
1037 spin_unlock_irq(&lo
->lo_lock
);
1039 loop_release_xfer(lo
);
1040 lo
->transfer
= NULL
;
1042 lo
->lo_device
= NULL
;
1043 lo
->lo_encryption
= NULL
;
1045 lo
->lo_sizelimit
= 0;
1046 lo
->lo_encrypt_key_size
= 0;
1047 memset(lo
->lo_encrypt_key
, 0, LO_KEY_SIZE
);
1048 memset(lo
->lo_crypt_name
, 0, LO_NAME_SIZE
);
1049 memset(lo
->lo_file_name
, 0, LO_NAME_SIZE
);
1052 invalidate_bdev(bdev
);
1054 set_capacity(lo
->lo_disk
, 0);
1055 loop_sysfs_exit(lo
);
1057 bd_set_size(bdev
, 0);
1058 /* let user-space know about this change */
1059 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1061 mapping_set_gfp_mask(filp
->f_mapping
, gfp
);
1062 lo
->lo_state
= Lo_unbound
;
1063 /* This is safe: open() is still holding a reference. */
1064 module_put(THIS_MODULE
);
1065 blk_mq_unfreeze_queue(lo
->lo_queue
);
1067 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
&& bdev
)
1068 loop_reread_partitions(lo
, bdev
);
1071 lo
->lo_disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1072 loop_unprepare_queue(lo
);
1073 mutex_unlock(&lo
->lo_ctl_mutex
);
1075 * Need not hold lo_ctl_mutex to fput backing file.
1076 * Calling fput holding lo_ctl_mutex triggers a circular
1077 * lock dependency possibility warning as fput can take
1078 * bd_mutex which is usually taken before lo_ctl_mutex.
1085 loop_set_status(struct loop_device
*lo
, const struct loop_info64
*info
)
1088 struct loop_func_table
*xfer
;
1089 kuid_t uid
= current_uid();
1091 if (lo
->lo_encrypt_key_size
&&
1092 !uid_eq(lo
->lo_key_owner
, uid
) &&
1093 !capable(CAP_SYS_ADMIN
))
1095 if (lo
->lo_state
!= Lo_bound
)
1097 if ((unsigned int) info
->lo_encrypt_key_size
> LO_KEY_SIZE
)
1100 err
= loop_release_xfer(lo
);
1104 if (info
->lo_encrypt_type
) {
1105 unsigned int type
= info
->lo_encrypt_type
;
1107 if (type
>= MAX_LO_CRYPT
)
1109 xfer
= xfer_funcs
[type
];
1115 err
= loop_init_xfer(lo
, xfer
, info
);
1119 if (lo
->lo_offset
!= info
->lo_offset
||
1120 lo
->lo_sizelimit
!= info
->lo_sizelimit
)
1121 if (figure_loop_size(lo
, info
->lo_offset
, info
->lo_sizelimit
))
1124 loop_config_discard(lo
);
1126 memcpy(lo
->lo_file_name
, info
->lo_file_name
, LO_NAME_SIZE
);
1127 memcpy(lo
->lo_crypt_name
, info
->lo_crypt_name
, LO_NAME_SIZE
);
1128 lo
->lo_file_name
[LO_NAME_SIZE
-1] = 0;
1129 lo
->lo_crypt_name
[LO_NAME_SIZE
-1] = 0;
1133 lo
->transfer
= xfer
->transfer
;
1134 lo
->ioctl
= xfer
->ioctl
;
1136 if ((lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) !=
1137 (info
->lo_flags
& LO_FLAGS_AUTOCLEAR
))
1138 lo
->lo_flags
^= LO_FLAGS_AUTOCLEAR
;
1140 if ((info
->lo_flags
& LO_FLAGS_PARTSCAN
) &&
1141 !(lo
->lo_flags
& LO_FLAGS_PARTSCAN
)) {
1142 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
1143 lo
->lo_disk
->flags
&= ~GENHD_FL_NO_PART_SCAN
;
1144 loop_reread_partitions(lo
, lo
->lo_device
);
1147 lo
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1148 lo
->lo_init
[0] = info
->lo_init
[0];
1149 lo
->lo_init
[1] = info
->lo_init
[1];
1150 if (info
->lo_encrypt_key_size
) {
1151 memcpy(lo
->lo_encrypt_key
, info
->lo_encrypt_key
,
1152 info
->lo_encrypt_key_size
);
1153 lo
->lo_key_owner
= uid
;
1156 /* update dio if lo_offset or transfer is changed */
1157 __loop_update_dio(lo
, lo
->use_dio
);
1163 loop_get_status(struct loop_device
*lo
, struct loop_info64
*info
)
1165 struct file
*file
= lo
->lo_backing_file
;
1169 if (lo
->lo_state
!= Lo_bound
)
1171 error
= vfs_getattr(&file
->f_path
, &stat
);
1174 memset(info
, 0, sizeof(*info
));
1175 info
->lo_number
= lo
->lo_number
;
1176 info
->lo_device
= huge_encode_dev(stat
.dev
);
1177 info
->lo_inode
= stat
.ino
;
1178 info
->lo_rdevice
= huge_encode_dev(lo
->lo_device
? stat
.rdev
: stat
.dev
);
1179 info
->lo_offset
= lo
->lo_offset
;
1180 info
->lo_sizelimit
= lo
->lo_sizelimit
;
1181 info
->lo_flags
= lo
->lo_flags
;
1182 memcpy(info
->lo_file_name
, lo
->lo_file_name
, LO_NAME_SIZE
);
1183 memcpy(info
->lo_crypt_name
, lo
->lo_crypt_name
, LO_NAME_SIZE
);
1184 info
->lo_encrypt_type
=
1185 lo
->lo_encryption
? lo
->lo_encryption
->number
: 0;
1186 if (lo
->lo_encrypt_key_size
&& capable(CAP_SYS_ADMIN
)) {
1187 info
->lo_encrypt_key_size
= lo
->lo_encrypt_key_size
;
1188 memcpy(info
->lo_encrypt_key
, lo
->lo_encrypt_key
,
1189 lo
->lo_encrypt_key_size
);
1195 loop_info64_from_old(const struct loop_info
*info
, struct loop_info64
*info64
)
1197 memset(info64
, 0, sizeof(*info64
));
1198 info64
->lo_number
= info
->lo_number
;
1199 info64
->lo_device
= info
->lo_device
;
1200 info64
->lo_inode
= info
->lo_inode
;
1201 info64
->lo_rdevice
= info
->lo_rdevice
;
1202 info64
->lo_offset
= info
->lo_offset
;
1203 info64
->lo_sizelimit
= 0;
1204 info64
->lo_encrypt_type
= info
->lo_encrypt_type
;
1205 info64
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1206 info64
->lo_flags
= info
->lo_flags
;
1207 info64
->lo_init
[0] = info
->lo_init
[0];
1208 info64
->lo_init
[1] = info
->lo_init
[1];
1209 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1210 memcpy(info64
->lo_crypt_name
, info
->lo_name
, LO_NAME_SIZE
);
1212 memcpy(info64
->lo_file_name
, info
->lo_name
, LO_NAME_SIZE
);
1213 memcpy(info64
->lo_encrypt_key
, info
->lo_encrypt_key
, LO_KEY_SIZE
);
1217 loop_info64_to_old(const struct loop_info64
*info64
, struct 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
)
1247 loop_set_status_old(struct loop_device
*lo
, const struct loop_info __user
*arg
)
1249 struct loop_info info
;
1250 struct loop_info64 info64
;
1252 if (copy_from_user(&info
, arg
, sizeof (struct loop_info
)))
1254 loop_info64_from_old(&info
, &info64
);
1255 return loop_set_status(lo
, &info64
);
1259 loop_set_status64(struct loop_device
*lo
, const struct loop_info64 __user
*arg
)
1261 struct loop_info64 info64
;
1263 if (copy_from_user(&info64
, arg
, sizeof (struct loop_info64
)))
1265 return loop_set_status(lo
, &info64
);
1269 loop_get_status_old(struct loop_device
*lo
, struct loop_info __user
*arg
) {
1270 struct loop_info info
;
1271 struct loop_info64 info64
;
1277 err
= loop_get_status(lo
, &info64
);
1279 err
= loop_info64_to_old(&info64
, &info
);
1280 if (!err
&& copy_to_user(arg
, &info
, sizeof(info
)))
1287 loop_get_status64(struct loop_device
*lo
, struct loop_info64 __user
*arg
) {
1288 struct loop_info64 info64
;
1294 err
= loop_get_status(lo
, &info64
);
1295 if (!err
&& copy_to_user(arg
, &info64
, sizeof(info64
)))
1301 static int loop_set_capacity(struct loop_device
*lo
, struct block_device
*bdev
)
1303 if (unlikely(lo
->lo_state
!= Lo_bound
))
1306 return figure_loop_size(lo
, lo
->lo_offset
, lo
->lo_sizelimit
);
1309 static int loop_set_dio(struct loop_device
*lo
, unsigned long arg
)
1312 if (lo
->lo_state
!= Lo_bound
)
1315 __loop_update_dio(lo
, !!arg
);
1316 if (lo
->use_dio
== !!arg
)
1323 static int lo_ioctl(struct block_device
*bdev
, fmode_t mode
,
1324 unsigned int cmd
, unsigned long arg
)
1326 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1329 mutex_lock_nested(&lo
->lo_ctl_mutex
, 1);
1332 err
= loop_set_fd(lo
, mode
, bdev
, arg
);
1334 case LOOP_CHANGE_FD
:
1335 err
= loop_change_fd(lo
, bdev
, arg
);
1338 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1339 err
= loop_clr_fd(lo
);
1343 case LOOP_SET_STATUS
:
1345 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1346 err
= loop_set_status_old(lo
,
1347 (struct loop_info __user
*)arg
);
1349 case LOOP_GET_STATUS
:
1350 err
= loop_get_status_old(lo
, (struct loop_info __user
*) arg
);
1352 case LOOP_SET_STATUS64
:
1354 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1355 err
= loop_set_status64(lo
,
1356 (struct loop_info64 __user
*) arg
);
1358 case LOOP_GET_STATUS64
:
1359 err
= loop_get_status64(lo
, (struct loop_info64 __user
*) arg
);
1361 case LOOP_SET_CAPACITY
:
1363 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1364 err
= loop_set_capacity(lo
, bdev
);
1366 case LOOP_SET_DIRECT_IO
:
1368 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1369 err
= loop_set_dio(lo
, arg
);
1372 err
= lo
->ioctl
? lo
->ioctl(lo
, cmd
, arg
) : -EINVAL
;
1374 mutex_unlock(&lo
->lo_ctl_mutex
);
1380 #ifdef CONFIG_COMPAT
1381 struct compat_loop_info
{
1382 compat_int_t lo_number
; /* ioctl r/o */
1383 compat_dev_t lo_device
; /* ioctl r/o */
1384 compat_ulong_t lo_inode
; /* ioctl r/o */
1385 compat_dev_t lo_rdevice
; /* ioctl r/o */
1386 compat_int_t lo_offset
;
1387 compat_int_t lo_encrypt_type
;
1388 compat_int_t lo_encrypt_key_size
; /* ioctl w/o */
1389 compat_int_t lo_flags
; /* ioctl r/o */
1390 char lo_name
[LO_NAME_SIZE
];
1391 unsigned char lo_encrypt_key
[LO_KEY_SIZE
]; /* ioctl w/o */
1392 compat_ulong_t lo_init
[2];
1397 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1398 * - noinlined to reduce stack space usage in main part of driver
1401 loop_info64_from_compat(const struct compat_loop_info __user
*arg
,
1402 struct loop_info64
*info64
)
1404 struct compat_loop_info info
;
1406 if (copy_from_user(&info
, arg
, sizeof(info
)))
1409 memset(info64
, 0, sizeof(*info64
));
1410 info64
->lo_number
= info
.lo_number
;
1411 info64
->lo_device
= info
.lo_device
;
1412 info64
->lo_inode
= info
.lo_inode
;
1413 info64
->lo_rdevice
= info
.lo_rdevice
;
1414 info64
->lo_offset
= info
.lo_offset
;
1415 info64
->lo_sizelimit
= 0;
1416 info64
->lo_encrypt_type
= info
.lo_encrypt_type
;
1417 info64
->lo_encrypt_key_size
= info
.lo_encrypt_key_size
;
1418 info64
->lo_flags
= info
.lo_flags
;
1419 info64
->lo_init
[0] = info
.lo_init
[0];
1420 info64
->lo_init
[1] = info
.lo_init
[1];
1421 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1422 memcpy(info64
->lo_crypt_name
, info
.lo_name
, LO_NAME_SIZE
);
1424 memcpy(info64
->lo_file_name
, info
.lo_name
, LO_NAME_SIZE
);
1425 memcpy(info64
->lo_encrypt_key
, info
.lo_encrypt_key
, LO_KEY_SIZE
);
1430 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1431 * - noinlined to reduce stack space usage in main part of driver
1434 loop_info64_to_compat(const struct loop_info64
*info64
,
1435 struct compat_loop_info __user
*arg
)
1437 struct compat_loop_info info
;
1439 memset(&info
, 0, sizeof(info
));
1440 info
.lo_number
= info64
->lo_number
;
1441 info
.lo_device
= info64
->lo_device
;
1442 info
.lo_inode
= info64
->lo_inode
;
1443 info
.lo_rdevice
= info64
->lo_rdevice
;
1444 info
.lo_offset
= info64
->lo_offset
;
1445 info
.lo_encrypt_type
= info64
->lo_encrypt_type
;
1446 info
.lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1447 info
.lo_flags
= info64
->lo_flags
;
1448 info
.lo_init
[0] = info64
->lo_init
[0];
1449 info
.lo_init
[1] = info64
->lo_init
[1];
1450 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1451 memcpy(info
.lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1453 memcpy(info
.lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1454 memcpy(info
.lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1456 /* error in case values were truncated */
1457 if (info
.lo_device
!= info64
->lo_device
||
1458 info
.lo_rdevice
!= info64
->lo_rdevice
||
1459 info
.lo_inode
!= info64
->lo_inode
||
1460 info
.lo_offset
!= info64
->lo_offset
||
1461 info
.lo_init
[0] != info64
->lo_init
[0] ||
1462 info
.lo_init
[1] != info64
->lo_init
[1])
1465 if (copy_to_user(arg
, &info
, sizeof(info
)))
1471 loop_set_status_compat(struct loop_device
*lo
,
1472 const struct compat_loop_info __user
*arg
)
1474 struct loop_info64 info64
;
1477 ret
= loop_info64_from_compat(arg
, &info64
);
1480 return loop_set_status(lo
, &info64
);
1484 loop_get_status_compat(struct loop_device
*lo
,
1485 struct compat_loop_info __user
*arg
)
1487 struct loop_info64 info64
;
1493 err
= loop_get_status(lo
, &info64
);
1495 err
= loop_info64_to_compat(&info64
, arg
);
1499 static int lo_compat_ioctl(struct block_device
*bdev
, fmode_t mode
,
1500 unsigned int cmd
, unsigned long arg
)
1502 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1506 case LOOP_SET_STATUS
:
1507 mutex_lock(&lo
->lo_ctl_mutex
);
1508 err
= loop_set_status_compat(
1509 lo
, (const struct compat_loop_info __user
*) arg
);
1510 mutex_unlock(&lo
->lo_ctl_mutex
);
1512 case LOOP_GET_STATUS
:
1513 mutex_lock(&lo
->lo_ctl_mutex
);
1514 err
= loop_get_status_compat(
1515 lo
, (struct compat_loop_info __user
*) arg
);
1516 mutex_unlock(&lo
->lo_ctl_mutex
);
1518 case LOOP_SET_CAPACITY
:
1520 case LOOP_GET_STATUS64
:
1521 case LOOP_SET_STATUS64
:
1522 arg
= (unsigned long) compat_ptr(arg
);
1524 case LOOP_CHANGE_FD
:
1525 err
= lo_ioctl(bdev
, mode
, cmd
, arg
);
1535 static int lo_open(struct block_device
*bdev
, fmode_t mode
)
1537 struct loop_device
*lo
;
1540 mutex_lock(&loop_index_mutex
);
1541 lo
= bdev
->bd_disk
->private_data
;
1547 atomic_inc(&lo
->lo_refcnt
);
1549 mutex_unlock(&loop_index_mutex
);
1553 static void lo_release(struct gendisk
*disk
, fmode_t mode
)
1555 struct loop_device
*lo
= disk
->private_data
;
1558 if (atomic_dec_return(&lo
->lo_refcnt
))
1561 mutex_lock(&lo
->lo_ctl_mutex
);
1562 if (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) {
1564 * In autoclear mode, stop the loop thread
1565 * and remove configuration after last close.
1567 err
= loop_clr_fd(lo
);
1572 * Otherwise keep thread (if running) and config,
1573 * but flush possible ongoing bios in thread.
1578 mutex_unlock(&lo
->lo_ctl_mutex
);
1581 static const struct block_device_operations lo_fops
= {
1582 .owner
= THIS_MODULE
,
1584 .release
= lo_release
,
1586 #ifdef CONFIG_COMPAT
1587 .compat_ioctl
= lo_compat_ioctl
,
1592 * And now the modules code and kernel interface.
1594 static int max_loop
;
1595 module_param(max_loop
, int, S_IRUGO
);
1596 MODULE_PARM_DESC(max_loop
, "Maximum number of loop devices");
1597 module_param(max_part
, int, S_IRUGO
);
1598 MODULE_PARM_DESC(max_part
, "Maximum number of partitions per loop device");
1599 MODULE_LICENSE("GPL");
1600 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR
);
1602 int loop_register_transfer(struct loop_func_table
*funcs
)
1604 unsigned int n
= funcs
->number
;
1606 if (n
>= MAX_LO_CRYPT
|| xfer_funcs
[n
])
1608 xfer_funcs
[n
] = funcs
;
1612 static int unregister_transfer_cb(int id
, void *ptr
, void *data
)
1614 struct loop_device
*lo
= ptr
;
1615 struct loop_func_table
*xfer
= data
;
1617 mutex_lock(&lo
->lo_ctl_mutex
);
1618 if (lo
->lo_encryption
== xfer
)
1619 loop_release_xfer(lo
);
1620 mutex_unlock(&lo
->lo_ctl_mutex
);
1624 int loop_unregister_transfer(int number
)
1626 unsigned int n
= number
;
1627 struct loop_func_table
*xfer
;
1629 if (n
== 0 || n
>= MAX_LO_CRYPT
|| (xfer
= xfer_funcs
[n
]) == NULL
)
1632 xfer_funcs
[n
] = NULL
;
1633 idr_for_each(&loop_index_idr
, &unregister_transfer_cb
, xfer
);
1637 EXPORT_SYMBOL(loop_register_transfer
);
1638 EXPORT_SYMBOL(loop_unregister_transfer
);
1640 static int loop_queue_rq(struct blk_mq_hw_ctx
*hctx
,
1641 const struct blk_mq_queue_data
*bd
)
1643 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(bd
->rq
);
1644 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1646 blk_mq_start_request(bd
->rq
);
1648 if (lo
->lo_state
!= Lo_bound
)
1651 switch (req_op(cmd
->rq
)) {
1653 case REQ_OP_DISCARD
:
1654 cmd
->use_aio
= false;
1657 cmd
->use_aio
= lo
->use_dio
;
1661 kthread_queue_work(&lo
->worker
, &cmd
->work
);
1663 return BLK_MQ_RQ_QUEUE_OK
;
1666 static void loop_handle_cmd(struct loop_cmd
*cmd
)
1668 const bool write
= op_is_write(req_op(cmd
->rq
));
1669 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1672 if (write
&& (lo
->lo_flags
& LO_FLAGS_READ_ONLY
)) {
1677 ret
= do_req_filebacked(lo
, cmd
->rq
);
1679 /* complete non-aio request */
1680 if (!cmd
->use_aio
|| ret
)
1681 blk_mq_complete_request(cmd
->rq
, ret
? -EIO
: 0);
1684 static void loop_queue_work(struct kthread_work
*work
)
1686 struct loop_cmd
*cmd
=
1687 container_of(work
, struct loop_cmd
, work
);
1689 loop_handle_cmd(cmd
);
1692 static int loop_init_request(void *data
, struct request
*rq
,
1693 unsigned int hctx_idx
, unsigned int request_idx
,
1694 unsigned int numa_node
)
1696 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
1699 kthread_init_work(&cmd
->work
, loop_queue_work
);
1704 static struct blk_mq_ops loop_mq_ops
= {
1705 .queue_rq
= loop_queue_rq
,
1706 .init_request
= loop_init_request
,
1709 static int loop_add(struct loop_device
**l
, int i
)
1711 struct loop_device
*lo
;
1712 struct gendisk
*disk
;
1716 lo
= kzalloc(sizeof(*lo
), GFP_KERNEL
);
1720 lo
->lo_state
= Lo_unbound
;
1722 /* allocate id, if @id >= 0, we're requesting that specific id */
1724 err
= idr_alloc(&loop_index_idr
, lo
, i
, i
+ 1, GFP_KERNEL
);
1728 err
= idr_alloc(&loop_index_idr
, lo
, 0, 0, GFP_KERNEL
);
1735 lo
->tag_set
.ops
= &loop_mq_ops
;
1736 lo
->tag_set
.nr_hw_queues
= 1;
1737 lo
->tag_set
.queue_depth
= 128;
1738 lo
->tag_set
.numa_node
= NUMA_NO_NODE
;
1739 lo
->tag_set
.cmd_size
= sizeof(struct loop_cmd
);
1740 lo
->tag_set
.flags
= BLK_MQ_F_SHOULD_MERGE
| BLK_MQ_F_SG_MERGE
;
1741 lo
->tag_set
.driver_data
= lo
;
1743 err
= blk_mq_alloc_tag_set(&lo
->tag_set
);
1747 lo
->lo_queue
= blk_mq_init_queue(&lo
->tag_set
);
1748 if (IS_ERR_OR_NULL(lo
->lo_queue
)) {
1749 err
= PTR_ERR(lo
->lo_queue
);
1750 goto out_cleanup_tags
;
1752 lo
->lo_queue
->queuedata
= lo
;
1755 * It doesn't make sense to enable merge because the I/O
1756 * submitted to backing file is handled page by page.
1758 queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES
, lo
->lo_queue
);
1761 disk
= lo
->lo_disk
= alloc_disk(1 << part_shift
);
1763 goto out_free_queue
;
1766 * Disable partition scanning by default. The in-kernel partition
1767 * scanning can be requested individually per-device during its
1768 * setup. Userspace can always add and remove partitions from all
1769 * devices. The needed partition minors are allocated from the
1770 * extended minor space, the main loop device numbers will continue
1771 * to match the loop minors, regardless of the number of partitions
1774 * If max_part is given, partition scanning is globally enabled for
1775 * all loop devices. The minors for the main loop devices will be
1776 * multiples of max_part.
1778 * Note: Global-for-all-devices, set-only-at-init, read-only module
1779 * parameteters like 'max_loop' and 'max_part' make things needlessly
1780 * complicated, are too static, inflexible and may surprise
1781 * userspace tools. Parameters like this in general should be avoided.
1784 disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1785 disk
->flags
|= GENHD_FL_EXT_DEVT
;
1786 mutex_init(&lo
->lo_ctl_mutex
);
1787 atomic_set(&lo
->lo_refcnt
, 0);
1789 spin_lock_init(&lo
->lo_lock
);
1790 disk
->major
= LOOP_MAJOR
;
1791 disk
->first_minor
= i
<< part_shift
;
1792 disk
->fops
= &lo_fops
;
1793 disk
->private_data
= lo
;
1794 disk
->queue
= lo
->lo_queue
;
1795 sprintf(disk
->disk_name
, "loop%d", i
);
1798 return lo
->lo_number
;
1801 blk_cleanup_queue(lo
->lo_queue
);
1803 blk_mq_free_tag_set(&lo
->tag_set
);
1805 idr_remove(&loop_index_idr
, i
);
1812 static void loop_remove(struct loop_device
*lo
)
1814 blk_cleanup_queue(lo
->lo_queue
);
1815 del_gendisk(lo
->lo_disk
);
1816 blk_mq_free_tag_set(&lo
->tag_set
);
1817 put_disk(lo
->lo_disk
);
1821 static int find_free_cb(int id
, void *ptr
, void *data
)
1823 struct loop_device
*lo
= ptr
;
1824 struct loop_device
**l
= data
;
1826 if (lo
->lo_state
== Lo_unbound
) {
1833 static int loop_lookup(struct loop_device
**l
, int i
)
1835 struct loop_device
*lo
;
1841 err
= idr_for_each(&loop_index_idr
, &find_free_cb
, &lo
);
1844 ret
= lo
->lo_number
;
1849 /* lookup and return a specific i */
1850 lo
= idr_find(&loop_index_idr
, i
);
1853 ret
= lo
->lo_number
;
1859 static struct kobject
*loop_probe(dev_t dev
, int *part
, void *data
)
1861 struct loop_device
*lo
;
1862 struct kobject
*kobj
;
1865 mutex_lock(&loop_index_mutex
);
1866 err
= loop_lookup(&lo
, MINOR(dev
) >> part_shift
);
1868 err
= loop_add(&lo
, MINOR(dev
) >> part_shift
);
1872 kobj
= get_disk(lo
->lo_disk
);
1873 mutex_unlock(&loop_index_mutex
);
1879 static long loop_control_ioctl(struct file
*file
, unsigned int cmd
,
1882 struct loop_device
*lo
;
1885 mutex_lock(&loop_index_mutex
);
1888 ret
= loop_lookup(&lo
, parm
);
1893 ret
= loop_add(&lo
, parm
);
1895 case LOOP_CTL_REMOVE
:
1896 ret
= loop_lookup(&lo
, parm
);
1899 mutex_lock(&lo
->lo_ctl_mutex
);
1900 if (lo
->lo_state
!= Lo_unbound
) {
1902 mutex_unlock(&lo
->lo_ctl_mutex
);
1905 if (atomic_read(&lo
->lo_refcnt
) > 0) {
1907 mutex_unlock(&lo
->lo_ctl_mutex
);
1910 lo
->lo_disk
->private_data
= NULL
;
1911 mutex_unlock(&lo
->lo_ctl_mutex
);
1912 idr_remove(&loop_index_idr
, lo
->lo_number
);
1915 case LOOP_CTL_GET_FREE
:
1916 ret
= loop_lookup(&lo
, -1);
1919 ret
= loop_add(&lo
, -1);
1921 mutex_unlock(&loop_index_mutex
);
1926 static const struct file_operations loop_ctl_fops
= {
1927 .open
= nonseekable_open
,
1928 .unlocked_ioctl
= loop_control_ioctl
,
1929 .compat_ioctl
= loop_control_ioctl
,
1930 .owner
= THIS_MODULE
,
1931 .llseek
= noop_llseek
,
1934 static struct miscdevice loop_misc
= {
1935 .minor
= LOOP_CTRL_MINOR
,
1936 .name
= "loop-control",
1937 .fops
= &loop_ctl_fops
,
1940 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR
);
1941 MODULE_ALIAS("devname:loop-control");
1943 static int __init
loop_init(void)
1946 unsigned long range
;
1947 struct loop_device
*lo
;
1950 err
= misc_register(&loop_misc
);
1956 part_shift
= fls(max_part
);
1959 * Adjust max_part according to part_shift as it is exported
1960 * to user space so that user can decide correct minor number
1961 * if [s]he want to create more devices.
1963 * Note that -1 is required because partition 0 is reserved
1964 * for the whole disk.
1966 max_part
= (1UL << part_shift
) - 1;
1969 if ((1UL << part_shift
) > DISK_MAX_PARTS
) {
1974 if (max_loop
> 1UL << (MINORBITS
- part_shift
)) {
1980 * If max_loop is specified, create that many devices upfront.
1981 * This also becomes a hard limit. If max_loop is not specified,
1982 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1983 * init time. Loop devices can be requested on-demand with the
1984 * /dev/loop-control interface, or be instantiated by accessing
1985 * a 'dead' device node.
1989 range
= max_loop
<< part_shift
;
1991 nr
= CONFIG_BLK_DEV_LOOP_MIN_COUNT
;
1992 range
= 1UL << MINORBITS
;
1995 if (register_blkdev(LOOP_MAJOR
, "loop")) {
2000 blk_register_region(MKDEV(LOOP_MAJOR
, 0), range
,
2001 THIS_MODULE
, loop_probe
, NULL
, NULL
);
2003 /* pre-create number of devices given by config or max_loop */
2004 mutex_lock(&loop_index_mutex
);
2005 for (i
= 0; i
< nr
; i
++)
2007 mutex_unlock(&loop_index_mutex
);
2009 printk(KERN_INFO
"loop: module loaded\n");
2013 misc_deregister(&loop_misc
);
2017 static int loop_exit_cb(int id
, void *ptr
, void *data
)
2019 struct loop_device
*lo
= ptr
;
2025 static void __exit
loop_exit(void)
2027 unsigned long range
;
2029 range
= max_loop
? max_loop
<< part_shift
: 1UL << MINORBITS
;
2031 idr_for_each(&loop_index_idr
, &loop_exit_cb
, NULL
);
2032 idr_destroy(&loop_index_idr
);
2034 blk_unregister_region(MKDEV(LOOP_MAJOR
, 0), range
);
2035 unregister_blkdev(LOOP_MAJOR
, "loop");
2037 misc_deregister(&loop_misc
);
2040 module_init(loop_init
);
2041 module_exit(loop_exit
);
2044 static int __init
max_loop_setup(char *str
)
2046 max_loop
= simple_strtol(str
, NULL
, 0);
2050 __setup("max_loop=", max_loop_setup
);