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 <linux/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 applications should be PAGE_SIZE aligned
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
,
225 loff_t logical_blocksize
)
227 loff_t size
= get_size(offset
, sizelimit
, lo
->lo_backing_file
);
228 sector_t x
= (sector_t
)size
;
229 struct block_device
*bdev
= lo
->lo_device
;
231 if (unlikely((loff_t
)x
!= size
))
233 if (lo
->lo_offset
!= offset
)
234 lo
->lo_offset
= offset
;
235 if (lo
->lo_sizelimit
!= sizelimit
)
236 lo
->lo_sizelimit
= sizelimit
;
237 if (lo
->lo_flags
& LO_FLAGS_BLOCKSIZE
) {
238 lo
->lo_logical_blocksize
= logical_blocksize
;
239 blk_queue_physical_block_size(lo
->lo_queue
, lo
->lo_blocksize
);
240 blk_queue_logical_block_size(lo
->lo_queue
,
241 lo
->lo_logical_blocksize
);
243 set_capacity(lo
->lo_disk
, x
);
244 bd_set_size(bdev
, (loff_t
)get_capacity(bdev
->bd_disk
) << 9);
245 /* let user-space know about the new size */
246 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
251 lo_do_transfer(struct loop_device
*lo
, int cmd
,
252 struct page
*rpage
, unsigned roffs
,
253 struct page
*lpage
, unsigned loffs
,
254 int size
, sector_t rblock
)
258 ret
= lo
->transfer(lo
, cmd
, rpage
, roffs
, lpage
, loffs
, size
, rblock
);
262 printk_ratelimited(KERN_ERR
263 "loop: Transfer error at byte offset %llu, length %i.\n",
264 (unsigned long long)rblock
<< 9, size
);
268 static int lo_write_bvec(struct file
*file
, struct bio_vec
*bvec
, loff_t
*ppos
)
273 iov_iter_bvec(&i
, ITER_BVEC
, bvec
, 1, bvec
->bv_len
);
275 file_start_write(file
);
276 bw
= vfs_iter_write(file
, &i
, ppos
);
277 file_end_write(file
);
279 if (likely(bw
== bvec
->bv_len
))
282 printk_ratelimited(KERN_ERR
283 "loop: Write error at byte offset %llu, length %i.\n",
284 (unsigned long long)*ppos
, bvec
->bv_len
);
290 static int lo_write_simple(struct loop_device
*lo
, struct request
*rq
,
294 struct req_iterator iter
;
297 rq_for_each_segment(bvec
, rq
, iter
) {
298 ret
= lo_write_bvec(lo
->lo_backing_file
, &bvec
, &pos
);
308 * This is the slow, transforming version that needs to double buffer the
309 * data as it cannot do the transformations in place without having direct
310 * access to the destination pages of the backing file.
312 static int lo_write_transfer(struct loop_device
*lo
, struct request
*rq
,
315 struct bio_vec bvec
, b
;
316 struct req_iterator iter
;
320 page
= alloc_page(GFP_NOIO
);
324 rq_for_each_segment(bvec
, rq
, iter
) {
325 ret
= lo_do_transfer(lo
, WRITE
, page
, 0, bvec
.bv_page
,
326 bvec
.bv_offset
, bvec
.bv_len
, pos
>> 9);
332 b
.bv_len
= bvec
.bv_len
;
333 ret
= lo_write_bvec(lo
->lo_backing_file
, &b
, &pos
);
342 static int lo_read_simple(struct loop_device
*lo
, struct request
*rq
,
346 struct req_iterator iter
;
350 rq_for_each_segment(bvec
, rq
, iter
) {
351 iov_iter_bvec(&i
, ITER_BVEC
, &bvec
, 1, bvec
.bv_len
);
352 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
356 flush_dcache_page(bvec
.bv_page
);
358 if (len
!= bvec
.bv_len
) {
361 __rq_for_each_bio(bio
, rq
)
371 static int lo_read_transfer(struct loop_device
*lo
, struct request
*rq
,
374 struct bio_vec bvec
, b
;
375 struct req_iterator iter
;
381 page
= alloc_page(GFP_NOIO
);
385 rq_for_each_segment(bvec
, rq
, iter
) {
390 b
.bv_len
= bvec
.bv_len
;
392 iov_iter_bvec(&i
, ITER_BVEC
, &b
, 1, b
.bv_len
);
393 len
= vfs_iter_read(lo
->lo_backing_file
, &i
, &pos
);
399 ret
= lo_do_transfer(lo
, READ
, page
, 0, bvec
.bv_page
,
400 bvec
.bv_offset
, len
, offset
>> 9);
404 flush_dcache_page(bvec
.bv_page
);
406 if (len
!= bvec
.bv_len
) {
409 __rq_for_each_bio(bio
, rq
)
421 static int lo_discard(struct loop_device
*lo
, struct request
*rq
, loff_t pos
)
424 * We use punch hole to reclaim the free space used by the
425 * image a.k.a. discard. However we do not support discard if
426 * encryption is enabled, because it may give an attacker
427 * useful information.
429 struct file
*file
= lo
->lo_backing_file
;
430 int mode
= FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
;
433 if ((!file
->f_op
->fallocate
) || lo
->lo_encrypt_key_size
) {
438 ret
= file
->f_op
->fallocate(file
, mode
, pos
, blk_rq_bytes(rq
));
439 if (unlikely(ret
&& ret
!= -EINVAL
&& ret
!= -EOPNOTSUPP
))
445 static int lo_req_flush(struct loop_device
*lo
, struct request
*rq
)
447 struct file
*file
= lo
->lo_backing_file
;
448 int ret
= vfs_fsync(file
, 0);
449 if (unlikely(ret
&& ret
!= -EINVAL
))
455 static void lo_complete_rq(struct request
*rq
)
457 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
459 if (unlikely(req_op(cmd
->rq
) == REQ_OP_READ
&& cmd
->use_aio
&&
460 cmd
->ret
>= 0 && cmd
->ret
< blk_rq_bytes(cmd
->rq
))) {
461 struct bio
*bio
= cmd
->rq
->bio
;
463 bio_advance(bio
, cmd
->ret
);
467 blk_mq_end_request(rq
, cmd
->ret
< 0 ? BLK_STS_IOERR
: BLK_STS_OK
);
470 static void lo_rw_aio_complete(struct kiocb
*iocb
, long ret
, long ret2
)
472 struct loop_cmd
*cmd
= container_of(iocb
, struct loop_cmd
, iocb
);
475 blk_mq_complete_request(cmd
->rq
);
478 static int lo_rw_aio(struct loop_device
*lo
, struct loop_cmd
*cmd
,
481 struct iov_iter iter
;
482 struct bio_vec
*bvec
;
483 struct bio
*bio
= cmd
->rq
->bio
;
484 struct file
*file
= lo
->lo_backing_file
;
487 /* nomerge for loop request queue */
488 WARN_ON(cmd
->rq
->bio
!= cmd
->rq
->biotail
);
490 bvec
= __bvec_iter_bvec(bio
->bi_io_vec
, bio
->bi_iter
);
491 iov_iter_bvec(&iter
, ITER_BVEC
| rw
, bvec
,
492 bio_segments(bio
), blk_rq_bytes(cmd
->rq
));
494 * This bio may be started from the middle of the 'bvec'
495 * because of bio splitting, so offset from the bvec must
496 * be passed to iov iterator
498 iter
.iov_offset
= bio
->bi_iter
.bi_bvec_done
;
500 cmd
->iocb
.ki_pos
= pos
;
501 cmd
->iocb
.ki_filp
= file
;
502 cmd
->iocb
.ki_complete
= lo_rw_aio_complete
;
503 cmd
->iocb
.ki_flags
= IOCB_DIRECT
;
506 ret
= call_write_iter(file
, &cmd
->iocb
, &iter
);
508 ret
= call_read_iter(file
, &cmd
->iocb
, &iter
);
510 if (ret
!= -EIOCBQUEUED
)
511 cmd
->iocb
.ki_complete(&cmd
->iocb
, ret
, 0);
515 static int do_req_filebacked(struct loop_device
*lo
, struct request
*rq
)
517 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
518 loff_t pos
= ((loff_t
) blk_rq_pos(rq
) << 9) + lo
->lo_offset
;
521 * lo_write_simple and lo_read_simple should have been covered
522 * by io submit style function like lo_rw_aio(), one blocker
523 * is that lo_read_simple() need to call flush_dcache_page after
524 * the page is written from kernel, and it isn't easy to handle
525 * this in io submit style function which submits all segments
526 * of the req at one time. And direct read IO doesn't need to
527 * run flush_dcache_page().
529 switch (req_op(rq
)) {
531 return lo_req_flush(lo
, rq
);
533 case REQ_OP_WRITE_ZEROES
:
534 return lo_discard(lo
, rq
, pos
);
537 return lo_write_transfer(lo
, rq
, pos
);
538 else if (cmd
->use_aio
)
539 return lo_rw_aio(lo
, cmd
, pos
, WRITE
);
541 return lo_write_simple(lo
, rq
, pos
);
544 return lo_read_transfer(lo
, rq
, pos
);
545 else if (cmd
->use_aio
)
546 return lo_rw_aio(lo
, cmd
, pos
, READ
);
548 return lo_read_simple(lo
, rq
, pos
);
556 struct switch_request
{
558 struct completion wait
;
561 static inline void loop_update_dio(struct loop_device
*lo
)
563 __loop_update_dio(lo
, io_is_direct(lo
->lo_backing_file
) |
568 * Do the actual switch; called from the BIO completion routine
570 static void do_loop_switch(struct loop_device
*lo
, struct switch_request
*p
)
572 struct file
*file
= p
->file
;
573 struct file
*old_file
= lo
->lo_backing_file
;
574 struct address_space
*mapping
;
576 /* if no new file, only flush of queued bios requested */
580 mapping
= file
->f_mapping
;
581 mapping_set_gfp_mask(old_file
->f_mapping
, lo
->old_gfp_mask
);
582 lo
->lo_backing_file
= file
;
583 lo
->lo_blocksize
= S_ISBLK(mapping
->host
->i_mode
) ?
584 mapping
->host
->i_bdev
->bd_block_size
: PAGE_SIZE
;
585 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
586 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
591 * loop_switch performs the hard work of switching a backing store.
592 * First it needs to flush existing IO, it does this by sending a magic
593 * BIO down the pipe. The completion of this BIO does the actual switch.
595 static int loop_switch(struct loop_device
*lo
, struct file
*file
)
597 struct switch_request w
;
601 /* freeze queue and wait for completion of scheduled requests */
602 blk_mq_freeze_queue(lo
->lo_queue
);
604 /* do the switch action */
605 do_loop_switch(lo
, &w
);
608 blk_mq_unfreeze_queue(lo
->lo_queue
);
614 * Helper to flush the IOs in loop, but keeping loop thread running
616 static int loop_flush(struct loop_device
*lo
)
618 return loop_switch(lo
, NULL
);
621 static void loop_reread_partitions(struct loop_device
*lo
,
622 struct block_device
*bdev
)
627 * bd_mutex has been held already in release path, so don't
628 * acquire it if this function is called in such case.
630 * If the reread partition isn't from release path, lo_refcnt
631 * must be at least one and it can only become zero when the
632 * current holder is released.
634 if (!atomic_read(&lo
->lo_refcnt
))
635 rc
= __blkdev_reread_part(bdev
);
637 rc
= blkdev_reread_part(bdev
);
639 pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
640 __func__
, lo
->lo_number
, lo
->lo_file_name
, rc
);
644 * loop_change_fd switched the backing store of a loopback device to
645 * a new file. This is useful for operating system installers to free up
646 * the original file and in High Availability environments to switch to
647 * an alternative location for the content in case of server meltdown.
648 * This can only work if the loop device is used read-only, and if the
649 * new backing store is the same size and type as the old backing store.
651 static int loop_change_fd(struct loop_device
*lo
, struct block_device
*bdev
,
654 struct file
*file
, *old_file
;
659 if (lo
->lo_state
!= Lo_bound
)
662 /* the loop device has to be read-only */
664 if (!(lo
->lo_flags
& LO_FLAGS_READ_ONLY
))
672 inode
= file
->f_mapping
->host
;
673 old_file
= lo
->lo_backing_file
;
677 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
680 /* size of the new backing store needs to be the same */
681 if (get_loop_size(lo
, file
) != get_loop_size(lo
, old_file
))
685 error
= loop_switch(lo
, file
);
690 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
691 loop_reread_partitions(lo
, bdev
);
700 static inline int is_loop_device(struct file
*file
)
702 struct inode
*i
= file
->f_mapping
->host
;
704 return i
&& S_ISBLK(i
->i_mode
) && MAJOR(i
->i_rdev
) == LOOP_MAJOR
;
707 /* loop sysfs attributes */
709 static ssize_t
loop_attr_show(struct device
*dev
, char *page
,
710 ssize_t (*callback
)(struct loop_device
*, char *))
712 struct gendisk
*disk
= dev_to_disk(dev
);
713 struct loop_device
*lo
= disk
->private_data
;
715 return callback(lo
, page
);
718 #define LOOP_ATTR_RO(_name) \
719 static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
720 static ssize_t loop_attr_do_show_##_name(struct device *d, \
721 struct device_attribute *attr, char *b) \
723 return loop_attr_show(d, b, loop_attr_##_name##_show); \
725 static struct device_attribute loop_attr_##_name = \
726 __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
728 static ssize_t
loop_attr_backing_file_show(struct loop_device
*lo
, char *buf
)
733 spin_lock_irq(&lo
->lo_lock
);
734 if (lo
->lo_backing_file
)
735 p
= file_path(lo
->lo_backing_file
, buf
, PAGE_SIZE
- 1);
736 spin_unlock_irq(&lo
->lo_lock
);
738 if (IS_ERR_OR_NULL(p
))
742 memmove(buf
, p
, ret
);
750 static ssize_t
loop_attr_offset_show(struct loop_device
*lo
, char *buf
)
752 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_offset
);
755 static ssize_t
loop_attr_sizelimit_show(struct loop_device
*lo
, char *buf
)
757 return sprintf(buf
, "%llu\n", (unsigned long long)lo
->lo_sizelimit
);
760 static ssize_t
loop_attr_autoclear_show(struct loop_device
*lo
, char *buf
)
762 int autoclear
= (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
);
764 return sprintf(buf
, "%s\n", autoclear
? "1" : "0");
767 static ssize_t
loop_attr_partscan_show(struct loop_device
*lo
, char *buf
)
769 int partscan
= (lo
->lo_flags
& LO_FLAGS_PARTSCAN
);
771 return sprintf(buf
, "%s\n", partscan
? "1" : "0");
774 static ssize_t
loop_attr_dio_show(struct loop_device
*lo
, char *buf
)
776 int dio
= (lo
->lo_flags
& LO_FLAGS_DIRECT_IO
);
778 return sprintf(buf
, "%s\n", dio
? "1" : "0");
781 LOOP_ATTR_RO(backing_file
);
782 LOOP_ATTR_RO(offset
);
783 LOOP_ATTR_RO(sizelimit
);
784 LOOP_ATTR_RO(autoclear
);
785 LOOP_ATTR_RO(partscan
);
788 static struct attribute
*loop_attrs
[] = {
789 &loop_attr_backing_file
.attr
,
790 &loop_attr_offset
.attr
,
791 &loop_attr_sizelimit
.attr
,
792 &loop_attr_autoclear
.attr
,
793 &loop_attr_partscan
.attr
,
798 static struct attribute_group loop_attribute_group
= {
803 static int loop_sysfs_init(struct loop_device
*lo
)
805 return sysfs_create_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
806 &loop_attribute_group
);
809 static void loop_sysfs_exit(struct loop_device
*lo
)
811 sysfs_remove_group(&disk_to_dev(lo
->lo_disk
)->kobj
,
812 &loop_attribute_group
);
815 static void loop_config_discard(struct loop_device
*lo
)
817 struct file
*file
= lo
->lo_backing_file
;
818 struct inode
*inode
= file
->f_mapping
->host
;
819 struct request_queue
*q
= lo
->lo_queue
;
823 * We use punch hole to reclaim the free space used by the
824 * image a.k.a. discard. However we do not support discard if
825 * encryption is enabled, because it may give an attacker
826 * useful information.
828 if ((!file
->f_op
->fallocate
) ||
829 lo
->lo_encrypt_key_size
) {
830 q
->limits
.discard_granularity
= 0;
831 q
->limits
.discard_alignment
= 0;
832 blk_queue_max_discard_sectors(q
, 0);
833 blk_queue_max_write_zeroes_sectors(q
, 0);
834 queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD
, q
);
838 q
->limits
.discard_granularity
= inode
->i_sb
->s_blocksize
;
839 q
->limits
.discard_alignment
= 0;
840 if (lo
->lo_flags
& LO_FLAGS_BLOCKSIZE
)
841 lo_bits
= blksize_bits(lo
->lo_logical_blocksize
);
843 blk_queue_max_discard_sectors(q
, UINT_MAX
>> lo_bits
);
844 blk_queue_max_write_zeroes_sectors(q
, UINT_MAX
>> lo_bits
);
845 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD
, q
);
848 static void loop_unprepare_queue(struct loop_device
*lo
)
850 kthread_flush_worker(&lo
->worker
);
851 kthread_stop(lo
->worker_task
);
854 static int loop_prepare_queue(struct loop_device
*lo
)
856 kthread_init_worker(&lo
->worker
);
857 lo
->worker_task
= kthread_run(kthread_worker_fn
,
858 &lo
->worker
, "loop%d", lo
->lo_number
);
859 if (IS_ERR(lo
->worker_task
))
861 set_user_nice(lo
->worker_task
, MIN_NICE
);
865 static int loop_set_fd(struct loop_device
*lo
, fmode_t mode
,
866 struct block_device
*bdev
, unsigned int arg
)
868 struct file
*file
, *f
;
870 struct address_space
*mapping
;
871 unsigned lo_blocksize
;
876 /* This is safe, since we have a reference from open(). */
877 __module_get(THIS_MODULE
);
885 if (lo
->lo_state
!= Lo_unbound
)
888 /* Avoid recursion */
890 while (is_loop_device(f
)) {
891 struct loop_device
*l
;
893 if (f
->f_mapping
->host
->i_bdev
== bdev
)
896 l
= f
->f_mapping
->host
->i_bdev
->bd_disk
->private_data
;
897 if (l
->lo_state
== Lo_unbound
) {
901 f
= l
->lo_backing_file
;
904 mapping
= file
->f_mapping
;
905 inode
= mapping
->host
;
908 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
911 if (!(file
->f_mode
& FMODE_WRITE
) || !(mode
& FMODE_WRITE
) ||
912 !file
->f_op
->write_iter
)
913 lo_flags
|= LO_FLAGS_READ_ONLY
;
915 lo_blocksize
= S_ISBLK(inode
->i_mode
) ?
916 inode
->i_bdev
->bd_block_size
: PAGE_SIZE
;
919 size
= get_loop_size(lo
, file
);
920 if ((loff_t
)(sector_t
)size
!= size
)
922 error
= loop_prepare_queue(lo
);
928 set_device_ro(bdev
, (lo_flags
& LO_FLAGS_READ_ONLY
) != 0);
931 lo
->lo_blocksize
= lo_blocksize
;
932 lo
->lo_logical_blocksize
= 512;
933 lo
->lo_device
= bdev
;
934 lo
->lo_flags
= lo_flags
;
935 lo
->lo_backing_file
= file
;
938 lo
->lo_sizelimit
= 0;
939 lo
->old_gfp_mask
= mapping_gfp_mask(mapping
);
940 mapping_set_gfp_mask(mapping
, lo
->old_gfp_mask
& ~(__GFP_IO
|__GFP_FS
));
942 if (!(lo_flags
& LO_FLAGS_READ_ONLY
) && file
->f_op
->fsync
)
943 blk_queue_write_cache(lo
->lo_queue
, true, false);
946 set_capacity(lo
->lo_disk
, size
);
947 bd_set_size(bdev
, size
<< 9);
949 /* let user-space know about the new size */
950 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
952 set_blocksize(bdev
, lo_blocksize
);
954 lo
->lo_state
= Lo_bound
;
956 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
957 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
)
958 loop_reread_partitions(lo
, bdev
);
960 /* Grab the block_device to prevent its destruction after we
961 * put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
969 /* This is safe: open() is still holding a reference. */
970 module_put(THIS_MODULE
);
975 loop_release_xfer(struct loop_device
*lo
)
978 struct loop_func_table
*xfer
= lo
->lo_encryption
;
982 err
= xfer
->release(lo
);
984 lo
->lo_encryption
= NULL
;
985 module_put(xfer
->owner
);
991 loop_init_xfer(struct loop_device
*lo
, struct loop_func_table
*xfer
,
992 const struct loop_info64
*i
)
997 struct module
*owner
= xfer
->owner
;
999 if (!try_module_get(owner
))
1002 err
= xfer
->init(lo
, i
);
1006 lo
->lo_encryption
= xfer
;
1011 static int loop_clr_fd(struct loop_device
*lo
)
1013 struct file
*filp
= lo
->lo_backing_file
;
1014 gfp_t gfp
= lo
->old_gfp_mask
;
1015 struct block_device
*bdev
= lo
->lo_device
;
1017 if (lo
->lo_state
!= Lo_bound
)
1021 * If we've explicitly asked to tear down the loop device,
1022 * and it has an elevated reference count, set it for auto-teardown when
1023 * the last reference goes away. This stops $!~#$@ udev from
1024 * preventing teardown because it decided that it needs to run blkid on
1025 * the loopback device whenever they appear. xfstests is notorious for
1026 * failing tests because blkid via udev races with a losetup
1027 * <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
1028 * command to fail with EBUSY.
1030 if (atomic_read(&lo
->lo_refcnt
) > 1) {
1031 lo
->lo_flags
|= LO_FLAGS_AUTOCLEAR
;
1032 mutex_unlock(&lo
->lo_ctl_mutex
);
1039 /* freeze request queue during the transition */
1040 blk_mq_freeze_queue(lo
->lo_queue
);
1042 spin_lock_irq(&lo
->lo_lock
);
1043 lo
->lo_state
= Lo_rundown
;
1044 lo
->lo_backing_file
= NULL
;
1045 spin_unlock_irq(&lo
->lo_lock
);
1047 loop_release_xfer(lo
);
1048 lo
->transfer
= NULL
;
1050 lo
->lo_device
= NULL
;
1051 lo
->lo_encryption
= NULL
;
1053 lo
->lo_sizelimit
= 0;
1054 lo
->lo_encrypt_key_size
= 0;
1055 memset(lo
->lo_encrypt_key
, 0, LO_KEY_SIZE
);
1056 memset(lo
->lo_crypt_name
, 0, LO_NAME_SIZE
);
1057 memset(lo
->lo_file_name
, 0, LO_NAME_SIZE
);
1060 invalidate_bdev(bdev
);
1062 set_capacity(lo
->lo_disk
, 0);
1063 loop_sysfs_exit(lo
);
1065 bd_set_size(bdev
, 0);
1066 /* let user-space know about this change */
1067 kobject_uevent(&disk_to_dev(bdev
->bd_disk
)->kobj
, KOBJ_CHANGE
);
1069 mapping_set_gfp_mask(filp
->f_mapping
, gfp
);
1070 lo
->lo_state
= Lo_unbound
;
1071 /* This is safe: open() is still holding a reference. */
1072 module_put(THIS_MODULE
);
1073 blk_mq_unfreeze_queue(lo
->lo_queue
);
1075 if (lo
->lo_flags
& LO_FLAGS_PARTSCAN
&& bdev
)
1076 loop_reread_partitions(lo
, bdev
);
1079 lo
->lo_disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1080 loop_unprepare_queue(lo
);
1081 mutex_unlock(&lo
->lo_ctl_mutex
);
1083 * Need not hold lo_ctl_mutex to fput backing file.
1084 * Calling fput holding lo_ctl_mutex triggers a circular
1085 * lock dependency possibility warning as fput can take
1086 * bd_mutex which is usually taken before lo_ctl_mutex.
1093 loop_set_status(struct loop_device
*lo
, const struct loop_info64
*info
)
1096 struct loop_func_table
*xfer
;
1097 kuid_t uid
= current_uid();
1098 int lo_flags
= lo
->lo_flags
;
1100 if (lo
->lo_encrypt_key_size
&&
1101 !uid_eq(lo
->lo_key_owner
, uid
) &&
1102 !capable(CAP_SYS_ADMIN
))
1104 if (lo
->lo_state
!= Lo_bound
)
1106 if ((unsigned int) info
->lo_encrypt_key_size
> LO_KEY_SIZE
)
1109 /* I/O need to be drained during transfer transition */
1110 blk_mq_freeze_queue(lo
->lo_queue
);
1112 err
= loop_release_xfer(lo
);
1116 if (info
->lo_encrypt_type
) {
1117 unsigned int type
= info
->lo_encrypt_type
;
1119 if (type
>= MAX_LO_CRYPT
)
1121 xfer
= xfer_funcs
[type
];
1127 err
= loop_init_xfer(lo
, xfer
, info
);
1131 if (info
->lo_flags
& LO_FLAGS_BLOCKSIZE
) {
1132 if (!(lo
->lo_flags
& LO_FLAGS_BLOCKSIZE
))
1133 lo
->lo_logical_blocksize
= 512;
1134 lo
->lo_flags
|= LO_FLAGS_BLOCKSIZE
;
1135 if (LO_INFO_BLOCKSIZE(info
) != 512 &&
1136 LO_INFO_BLOCKSIZE(info
) != 1024 &&
1137 LO_INFO_BLOCKSIZE(info
) != 2048 &&
1138 LO_INFO_BLOCKSIZE(info
) != 4096)
1140 if (LO_INFO_BLOCKSIZE(info
) > lo
->lo_blocksize
)
1144 if (lo
->lo_offset
!= info
->lo_offset
||
1145 lo
->lo_sizelimit
!= info
->lo_sizelimit
||
1146 lo
->lo_flags
!= lo_flags
||
1147 ((lo
->lo_flags
& LO_FLAGS_BLOCKSIZE
) &&
1148 lo
->lo_logical_blocksize
!= LO_INFO_BLOCKSIZE(info
))) {
1149 if (figure_loop_size(lo
, info
->lo_offset
, info
->lo_sizelimit
,
1150 LO_INFO_BLOCKSIZE(info
))) {
1156 loop_config_discard(lo
);
1158 memcpy(lo
->lo_file_name
, info
->lo_file_name
, LO_NAME_SIZE
);
1159 memcpy(lo
->lo_crypt_name
, info
->lo_crypt_name
, LO_NAME_SIZE
);
1160 lo
->lo_file_name
[LO_NAME_SIZE
-1] = 0;
1161 lo
->lo_crypt_name
[LO_NAME_SIZE
-1] = 0;
1165 lo
->transfer
= xfer
->transfer
;
1166 lo
->ioctl
= xfer
->ioctl
;
1168 if ((lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) !=
1169 (info
->lo_flags
& LO_FLAGS_AUTOCLEAR
))
1170 lo
->lo_flags
^= LO_FLAGS_AUTOCLEAR
;
1172 lo
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1173 lo
->lo_init
[0] = info
->lo_init
[0];
1174 lo
->lo_init
[1] = info
->lo_init
[1];
1175 if (info
->lo_encrypt_key_size
) {
1176 memcpy(lo
->lo_encrypt_key
, info
->lo_encrypt_key
,
1177 info
->lo_encrypt_key_size
);
1178 lo
->lo_key_owner
= uid
;
1181 /* update dio if lo_offset or transfer is changed */
1182 __loop_update_dio(lo
, lo
->use_dio
);
1185 blk_mq_unfreeze_queue(lo
->lo_queue
);
1187 if (!err
&& (info
->lo_flags
& LO_FLAGS_PARTSCAN
) &&
1188 !(lo
->lo_flags
& LO_FLAGS_PARTSCAN
)) {
1189 lo
->lo_flags
|= LO_FLAGS_PARTSCAN
;
1190 lo
->lo_disk
->flags
&= ~GENHD_FL_NO_PART_SCAN
;
1191 loop_reread_partitions(lo
, lo
->lo_device
);
1198 loop_get_status(struct loop_device
*lo
, struct loop_info64
*info
)
1200 struct file
*file
= lo
->lo_backing_file
;
1204 if (lo
->lo_state
!= Lo_bound
)
1206 error
= vfs_getattr(&file
->f_path
, &stat
,
1207 STATX_INO
, AT_STATX_SYNC_AS_STAT
);
1210 memset(info
, 0, sizeof(*info
));
1211 info
->lo_number
= lo
->lo_number
;
1212 info
->lo_device
= huge_encode_dev(stat
.dev
);
1213 info
->lo_inode
= stat
.ino
;
1214 info
->lo_rdevice
= huge_encode_dev(lo
->lo_device
? stat
.rdev
: stat
.dev
);
1215 info
->lo_offset
= lo
->lo_offset
;
1216 info
->lo_sizelimit
= lo
->lo_sizelimit
;
1217 info
->lo_flags
= lo
->lo_flags
;
1218 memcpy(info
->lo_file_name
, lo
->lo_file_name
, LO_NAME_SIZE
);
1219 memcpy(info
->lo_crypt_name
, lo
->lo_crypt_name
, LO_NAME_SIZE
);
1220 info
->lo_encrypt_type
=
1221 lo
->lo_encryption
? lo
->lo_encryption
->number
: 0;
1222 if (lo
->lo_encrypt_key_size
&& capable(CAP_SYS_ADMIN
)) {
1223 info
->lo_encrypt_key_size
= lo
->lo_encrypt_key_size
;
1224 memcpy(info
->lo_encrypt_key
, lo
->lo_encrypt_key
,
1225 lo
->lo_encrypt_key_size
);
1231 loop_info64_from_old(const struct loop_info
*info
, struct loop_info64
*info64
)
1233 memset(info64
, 0, sizeof(*info64
));
1234 info64
->lo_number
= info
->lo_number
;
1235 info64
->lo_device
= info
->lo_device
;
1236 info64
->lo_inode
= info
->lo_inode
;
1237 info64
->lo_rdevice
= info
->lo_rdevice
;
1238 info64
->lo_offset
= info
->lo_offset
;
1239 info64
->lo_sizelimit
= 0;
1240 info64
->lo_encrypt_type
= info
->lo_encrypt_type
;
1241 info64
->lo_encrypt_key_size
= info
->lo_encrypt_key_size
;
1242 info64
->lo_flags
= info
->lo_flags
;
1243 info64
->lo_init
[0] = info
->lo_init
[0];
1244 info64
->lo_init
[1] = info
->lo_init
[1];
1245 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1246 memcpy(info64
->lo_crypt_name
, info
->lo_name
, LO_NAME_SIZE
);
1248 memcpy(info64
->lo_file_name
, info
->lo_name
, LO_NAME_SIZE
);
1249 memcpy(info64
->lo_encrypt_key
, info
->lo_encrypt_key
, LO_KEY_SIZE
);
1253 loop_info64_to_old(const struct loop_info64
*info64
, struct loop_info
*info
)
1255 memset(info
, 0, sizeof(*info
));
1256 info
->lo_number
= info64
->lo_number
;
1257 info
->lo_device
= info64
->lo_device
;
1258 info
->lo_inode
= info64
->lo_inode
;
1259 info
->lo_rdevice
= info64
->lo_rdevice
;
1260 info
->lo_offset
= info64
->lo_offset
;
1261 info
->lo_encrypt_type
= info64
->lo_encrypt_type
;
1262 info
->lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1263 info
->lo_flags
= info64
->lo_flags
;
1264 info
->lo_init
[0] = info64
->lo_init
[0];
1265 info
->lo_init
[1] = info64
->lo_init
[1];
1266 if (info
->lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1267 memcpy(info
->lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1269 memcpy(info
->lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1270 memcpy(info
->lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1272 /* error in case values were truncated */
1273 if (info
->lo_device
!= info64
->lo_device
||
1274 info
->lo_rdevice
!= info64
->lo_rdevice
||
1275 info
->lo_inode
!= info64
->lo_inode
||
1276 info
->lo_offset
!= info64
->lo_offset
)
1283 loop_set_status_old(struct loop_device
*lo
, const struct loop_info __user
*arg
)
1285 struct loop_info info
;
1286 struct loop_info64 info64
;
1288 if (copy_from_user(&info
, arg
, sizeof (struct loop_info
)))
1290 loop_info64_from_old(&info
, &info64
);
1291 return loop_set_status(lo
, &info64
);
1295 loop_set_status64(struct loop_device
*lo
, const struct loop_info64 __user
*arg
)
1297 struct loop_info64 info64
;
1299 if (copy_from_user(&info64
, arg
, sizeof (struct loop_info64
)))
1301 return loop_set_status(lo
, &info64
);
1305 loop_get_status_old(struct loop_device
*lo
, struct loop_info __user
*arg
) {
1306 struct loop_info info
;
1307 struct loop_info64 info64
;
1313 err
= loop_get_status(lo
, &info64
);
1315 err
= loop_info64_to_old(&info64
, &info
);
1316 if (!err
&& copy_to_user(arg
, &info
, sizeof(info
)))
1323 loop_get_status64(struct loop_device
*lo
, struct loop_info64 __user
*arg
) {
1324 struct loop_info64 info64
;
1330 err
= loop_get_status(lo
, &info64
);
1331 if (!err
&& copy_to_user(arg
, &info64
, sizeof(info64
)))
1337 static int loop_set_capacity(struct loop_device
*lo
)
1339 if (unlikely(lo
->lo_state
!= Lo_bound
))
1342 return figure_loop_size(lo
, lo
->lo_offset
, lo
->lo_sizelimit
,
1343 lo
->lo_logical_blocksize
);
1346 static int loop_set_dio(struct loop_device
*lo
, unsigned long arg
)
1349 if (lo
->lo_state
!= Lo_bound
)
1352 __loop_update_dio(lo
, !!arg
);
1353 if (lo
->use_dio
== !!arg
)
1360 static int lo_ioctl(struct block_device
*bdev
, fmode_t mode
,
1361 unsigned int cmd
, unsigned long arg
)
1363 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1366 mutex_lock_nested(&lo
->lo_ctl_mutex
, 1);
1369 err
= loop_set_fd(lo
, mode
, bdev
, arg
);
1371 case LOOP_CHANGE_FD
:
1372 err
= loop_change_fd(lo
, bdev
, arg
);
1375 /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1376 err
= loop_clr_fd(lo
);
1380 case LOOP_SET_STATUS
:
1382 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1383 err
= loop_set_status_old(lo
,
1384 (struct loop_info __user
*)arg
);
1386 case LOOP_GET_STATUS
:
1387 err
= loop_get_status_old(lo
, (struct loop_info __user
*) arg
);
1389 case LOOP_SET_STATUS64
:
1391 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1392 err
= loop_set_status64(lo
,
1393 (struct loop_info64 __user
*) arg
);
1395 case LOOP_GET_STATUS64
:
1396 err
= loop_get_status64(lo
, (struct loop_info64 __user
*) arg
);
1398 case LOOP_SET_CAPACITY
:
1400 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1401 err
= loop_set_capacity(lo
);
1403 case LOOP_SET_DIRECT_IO
:
1405 if ((mode
& FMODE_WRITE
) || capable(CAP_SYS_ADMIN
))
1406 err
= loop_set_dio(lo
, arg
);
1409 err
= lo
->ioctl
? lo
->ioctl(lo
, cmd
, arg
) : -EINVAL
;
1411 mutex_unlock(&lo
->lo_ctl_mutex
);
1417 #ifdef CONFIG_COMPAT
1418 struct compat_loop_info
{
1419 compat_int_t lo_number
; /* ioctl r/o */
1420 compat_dev_t lo_device
; /* ioctl r/o */
1421 compat_ulong_t lo_inode
; /* ioctl r/o */
1422 compat_dev_t lo_rdevice
; /* ioctl r/o */
1423 compat_int_t lo_offset
;
1424 compat_int_t lo_encrypt_type
;
1425 compat_int_t lo_encrypt_key_size
; /* ioctl w/o */
1426 compat_int_t lo_flags
; /* ioctl r/o */
1427 char lo_name
[LO_NAME_SIZE
];
1428 unsigned char lo_encrypt_key
[LO_KEY_SIZE
]; /* ioctl w/o */
1429 compat_ulong_t lo_init
[2];
1434 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1435 * - noinlined to reduce stack space usage in main part of driver
1438 loop_info64_from_compat(const struct compat_loop_info __user
*arg
,
1439 struct loop_info64
*info64
)
1441 struct compat_loop_info info
;
1443 if (copy_from_user(&info
, arg
, sizeof(info
)))
1446 memset(info64
, 0, sizeof(*info64
));
1447 info64
->lo_number
= info
.lo_number
;
1448 info64
->lo_device
= info
.lo_device
;
1449 info64
->lo_inode
= info
.lo_inode
;
1450 info64
->lo_rdevice
= info
.lo_rdevice
;
1451 info64
->lo_offset
= info
.lo_offset
;
1452 info64
->lo_sizelimit
= 0;
1453 info64
->lo_encrypt_type
= info
.lo_encrypt_type
;
1454 info64
->lo_encrypt_key_size
= info
.lo_encrypt_key_size
;
1455 info64
->lo_flags
= info
.lo_flags
;
1456 info64
->lo_init
[0] = info
.lo_init
[0];
1457 info64
->lo_init
[1] = info
.lo_init
[1];
1458 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1459 memcpy(info64
->lo_crypt_name
, info
.lo_name
, LO_NAME_SIZE
);
1461 memcpy(info64
->lo_file_name
, info
.lo_name
, LO_NAME_SIZE
);
1462 memcpy(info64
->lo_encrypt_key
, info
.lo_encrypt_key
, LO_KEY_SIZE
);
1467 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1468 * - noinlined to reduce stack space usage in main part of driver
1471 loop_info64_to_compat(const struct loop_info64
*info64
,
1472 struct compat_loop_info __user
*arg
)
1474 struct compat_loop_info info
;
1476 memset(&info
, 0, sizeof(info
));
1477 info
.lo_number
= info64
->lo_number
;
1478 info
.lo_device
= info64
->lo_device
;
1479 info
.lo_inode
= info64
->lo_inode
;
1480 info
.lo_rdevice
= info64
->lo_rdevice
;
1481 info
.lo_offset
= info64
->lo_offset
;
1482 info
.lo_encrypt_type
= info64
->lo_encrypt_type
;
1483 info
.lo_encrypt_key_size
= info64
->lo_encrypt_key_size
;
1484 info
.lo_flags
= info64
->lo_flags
;
1485 info
.lo_init
[0] = info64
->lo_init
[0];
1486 info
.lo_init
[1] = info64
->lo_init
[1];
1487 if (info
.lo_encrypt_type
== LO_CRYPT_CRYPTOAPI
)
1488 memcpy(info
.lo_name
, info64
->lo_crypt_name
, LO_NAME_SIZE
);
1490 memcpy(info
.lo_name
, info64
->lo_file_name
, LO_NAME_SIZE
);
1491 memcpy(info
.lo_encrypt_key
, info64
->lo_encrypt_key
, LO_KEY_SIZE
);
1493 /* error in case values were truncated */
1494 if (info
.lo_device
!= info64
->lo_device
||
1495 info
.lo_rdevice
!= info64
->lo_rdevice
||
1496 info
.lo_inode
!= info64
->lo_inode
||
1497 info
.lo_offset
!= info64
->lo_offset
||
1498 info
.lo_init
[0] != info64
->lo_init
[0] ||
1499 info
.lo_init
[1] != info64
->lo_init
[1])
1502 if (copy_to_user(arg
, &info
, sizeof(info
)))
1508 loop_set_status_compat(struct loop_device
*lo
,
1509 const struct compat_loop_info __user
*arg
)
1511 struct loop_info64 info64
;
1514 ret
= loop_info64_from_compat(arg
, &info64
);
1517 return loop_set_status(lo
, &info64
);
1521 loop_get_status_compat(struct loop_device
*lo
,
1522 struct compat_loop_info __user
*arg
)
1524 struct loop_info64 info64
;
1530 err
= loop_get_status(lo
, &info64
);
1532 err
= loop_info64_to_compat(&info64
, arg
);
1536 static int lo_compat_ioctl(struct block_device
*bdev
, fmode_t mode
,
1537 unsigned int cmd
, unsigned long arg
)
1539 struct loop_device
*lo
= bdev
->bd_disk
->private_data
;
1543 case LOOP_SET_STATUS
:
1544 mutex_lock(&lo
->lo_ctl_mutex
);
1545 err
= loop_set_status_compat(
1546 lo
, (const struct compat_loop_info __user
*) arg
);
1547 mutex_unlock(&lo
->lo_ctl_mutex
);
1549 case LOOP_GET_STATUS
:
1550 mutex_lock(&lo
->lo_ctl_mutex
);
1551 err
= loop_get_status_compat(
1552 lo
, (struct compat_loop_info __user
*) arg
);
1553 mutex_unlock(&lo
->lo_ctl_mutex
);
1555 case LOOP_SET_CAPACITY
:
1557 case LOOP_GET_STATUS64
:
1558 case LOOP_SET_STATUS64
:
1559 arg
= (unsigned long) compat_ptr(arg
);
1561 case LOOP_CHANGE_FD
:
1562 err
= lo_ioctl(bdev
, mode
, cmd
, arg
);
1572 static int lo_open(struct block_device
*bdev
, fmode_t mode
)
1574 struct loop_device
*lo
;
1577 mutex_lock(&loop_index_mutex
);
1578 lo
= bdev
->bd_disk
->private_data
;
1584 atomic_inc(&lo
->lo_refcnt
);
1586 mutex_unlock(&loop_index_mutex
);
1590 static void lo_release(struct gendisk
*disk
, fmode_t mode
)
1592 struct loop_device
*lo
= disk
->private_data
;
1595 if (atomic_dec_return(&lo
->lo_refcnt
))
1598 mutex_lock(&lo
->lo_ctl_mutex
);
1599 if (lo
->lo_flags
& LO_FLAGS_AUTOCLEAR
) {
1601 * In autoclear mode, stop the loop thread
1602 * and remove configuration after last close.
1604 err
= loop_clr_fd(lo
);
1609 * Otherwise keep thread (if running) and config,
1610 * but flush possible ongoing bios in thread.
1615 mutex_unlock(&lo
->lo_ctl_mutex
);
1618 static const struct block_device_operations lo_fops
= {
1619 .owner
= THIS_MODULE
,
1621 .release
= lo_release
,
1623 #ifdef CONFIG_COMPAT
1624 .compat_ioctl
= lo_compat_ioctl
,
1629 * And now the modules code and kernel interface.
1631 static int max_loop
;
1632 module_param(max_loop
, int, S_IRUGO
);
1633 MODULE_PARM_DESC(max_loop
, "Maximum number of loop devices");
1634 module_param(max_part
, int, S_IRUGO
);
1635 MODULE_PARM_DESC(max_part
, "Maximum number of partitions per loop device");
1636 MODULE_LICENSE("GPL");
1637 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR
);
1639 int loop_register_transfer(struct loop_func_table
*funcs
)
1641 unsigned int n
= funcs
->number
;
1643 if (n
>= MAX_LO_CRYPT
|| xfer_funcs
[n
])
1645 xfer_funcs
[n
] = funcs
;
1649 static int unregister_transfer_cb(int id
, void *ptr
, void *data
)
1651 struct loop_device
*lo
= ptr
;
1652 struct loop_func_table
*xfer
= data
;
1654 mutex_lock(&lo
->lo_ctl_mutex
);
1655 if (lo
->lo_encryption
== xfer
)
1656 loop_release_xfer(lo
);
1657 mutex_unlock(&lo
->lo_ctl_mutex
);
1661 int loop_unregister_transfer(int number
)
1663 unsigned int n
= number
;
1664 struct loop_func_table
*xfer
;
1666 if (n
== 0 || n
>= MAX_LO_CRYPT
|| (xfer
= xfer_funcs
[n
]) == NULL
)
1669 xfer_funcs
[n
] = NULL
;
1670 idr_for_each(&loop_index_idr
, &unregister_transfer_cb
, xfer
);
1674 EXPORT_SYMBOL(loop_register_transfer
);
1675 EXPORT_SYMBOL(loop_unregister_transfer
);
1677 static int loop_queue_rq(struct blk_mq_hw_ctx
*hctx
,
1678 const struct blk_mq_queue_data
*bd
)
1680 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(bd
->rq
);
1681 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1683 blk_mq_start_request(bd
->rq
);
1685 if (lo
->lo_state
!= Lo_bound
)
1686 return BLK_MQ_RQ_QUEUE_ERROR
;
1688 switch (req_op(cmd
->rq
)) {
1690 case REQ_OP_DISCARD
:
1691 case REQ_OP_WRITE_ZEROES
:
1692 cmd
->use_aio
= false;
1695 cmd
->use_aio
= lo
->use_dio
;
1699 kthread_queue_work(&lo
->worker
, &cmd
->work
);
1701 return BLK_MQ_RQ_QUEUE_OK
;
1704 static void loop_handle_cmd(struct loop_cmd
*cmd
)
1706 const bool write
= op_is_write(req_op(cmd
->rq
));
1707 struct loop_device
*lo
= cmd
->rq
->q
->queuedata
;
1710 if (write
&& (lo
->lo_flags
& LO_FLAGS_READ_ONLY
)) {
1715 ret
= do_req_filebacked(lo
, cmd
->rq
);
1717 /* complete non-aio request */
1718 if (!cmd
->use_aio
|| ret
) {
1719 cmd
->ret
= ret
? -EIO
: 0;
1720 blk_mq_complete_request(cmd
->rq
);
1724 static void loop_queue_work(struct kthread_work
*work
)
1726 struct loop_cmd
*cmd
=
1727 container_of(work
, struct loop_cmd
, work
);
1729 loop_handle_cmd(cmd
);
1732 static int loop_init_request(struct blk_mq_tag_set
*set
, struct request
*rq
,
1733 unsigned int hctx_idx
, unsigned int numa_node
)
1735 struct loop_cmd
*cmd
= blk_mq_rq_to_pdu(rq
);
1738 kthread_init_work(&cmd
->work
, loop_queue_work
);
1743 static const struct blk_mq_ops loop_mq_ops
= {
1744 .queue_rq
= loop_queue_rq
,
1745 .init_request
= loop_init_request
,
1746 .complete
= lo_complete_rq
,
1749 static int loop_add(struct loop_device
**l
, int i
)
1751 struct loop_device
*lo
;
1752 struct gendisk
*disk
;
1756 lo
= kzalloc(sizeof(*lo
), GFP_KERNEL
);
1760 lo
->lo_state
= Lo_unbound
;
1762 /* allocate id, if @id >= 0, we're requesting that specific id */
1764 err
= idr_alloc(&loop_index_idr
, lo
, i
, i
+ 1, GFP_KERNEL
);
1768 err
= idr_alloc(&loop_index_idr
, lo
, 0, 0, GFP_KERNEL
);
1775 lo
->tag_set
.ops
= &loop_mq_ops
;
1776 lo
->tag_set
.nr_hw_queues
= 1;
1777 lo
->tag_set
.queue_depth
= 128;
1778 lo
->tag_set
.numa_node
= NUMA_NO_NODE
;
1779 lo
->tag_set
.cmd_size
= sizeof(struct loop_cmd
);
1780 lo
->tag_set
.flags
= BLK_MQ_F_SHOULD_MERGE
| BLK_MQ_F_SG_MERGE
;
1781 lo
->tag_set
.driver_data
= lo
;
1783 err
= blk_mq_alloc_tag_set(&lo
->tag_set
);
1787 lo
->lo_queue
= blk_mq_init_queue(&lo
->tag_set
);
1788 if (IS_ERR_OR_NULL(lo
->lo_queue
)) {
1789 err
= PTR_ERR(lo
->lo_queue
);
1790 goto out_cleanup_tags
;
1792 lo
->lo_queue
->queuedata
= lo
;
1795 * It doesn't make sense to enable merge because the I/O
1796 * submitted to backing file is handled page by page.
1798 queue_flag_set_unlocked(QUEUE_FLAG_NOMERGES
, lo
->lo_queue
);
1801 disk
= lo
->lo_disk
= alloc_disk(1 << part_shift
);
1803 goto out_free_queue
;
1806 * Disable partition scanning by default. The in-kernel partition
1807 * scanning can be requested individually per-device during its
1808 * setup. Userspace can always add and remove partitions from all
1809 * devices. The needed partition minors are allocated from the
1810 * extended minor space, the main loop device numbers will continue
1811 * to match the loop minors, regardless of the number of partitions
1814 * If max_part is given, partition scanning is globally enabled for
1815 * all loop devices. The minors for the main loop devices will be
1816 * multiples of max_part.
1818 * Note: Global-for-all-devices, set-only-at-init, read-only module
1819 * parameteters like 'max_loop' and 'max_part' make things needlessly
1820 * complicated, are too static, inflexible and may surprise
1821 * userspace tools. Parameters like this in general should be avoided.
1824 disk
->flags
|= GENHD_FL_NO_PART_SCAN
;
1825 disk
->flags
|= GENHD_FL_EXT_DEVT
;
1826 mutex_init(&lo
->lo_ctl_mutex
);
1827 atomic_set(&lo
->lo_refcnt
, 0);
1829 spin_lock_init(&lo
->lo_lock
);
1830 disk
->major
= LOOP_MAJOR
;
1831 disk
->first_minor
= i
<< part_shift
;
1832 disk
->fops
= &lo_fops
;
1833 disk
->private_data
= lo
;
1834 disk
->queue
= lo
->lo_queue
;
1835 sprintf(disk
->disk_name
, "loop%d", i
);
1838 return lo
->lo_number
;
1841 blk_cleanup_queue(lo
->lo_queue
);
1843 blk_mq_free_tag_set(&lo
->tag_set
);
1845 idr_remove(&loop_index_idr
, i
);
1852 static void loop_remove(struct loop_device
*lo
)
1854 blk_cleanup_queue(lo
->lo_queue
);
1855 del_gendisk(lo
->lo_disk
);
1856 blk_mq_free_tag_set(&lo
->tag_set
);
1857 put_disk(lo
->lo_disk
);
1861 static int find_free_cb(int id
, void *ptr
, void *data
)
1863 struct loop_device
*lo
= ptr
;
1864 struct loop_device
**l
= data
;
1866 if (lo
->lo_state
== Lo_unbound
) {
1873 static int loop_lookup(struct loop_device
**l
, int i
)
1875 struct loop_device
*lo
;
1881 err
= idr_for_each(&loop_index_idr
, &find_free_cb
, &lo
);
1884 ret
= lo
->lo_number
;
1889 /* lookup and return a specific i */
1890 lo
= idr_find(&loop_index_idr
, i
);
1893 ret
= lo
->lo_number
;
1899 static struct kobject
*loop_probe(dev_t dev
, int *part
, void *data
)
1901 struct loop_device
*lo
;
1902 struct kobject
*kobj
;
1905 mutex_lock(&loop_index_mutex
);
1906 err
= loop_lookup(&lo
, MINOR(dev
) >> part_shift
);
1908 err
= loop_add(&lo
, MINOR(dev
) >> part_shift
);
1912 kobj
= get_disk(lo
->lo_disk
);
1913 mutex_unlock(&loop_index_mutex
);
1919 static long loop_control_ioctl(struct file
*file
, unsigned int cmd
,
1922 struct loop_device
*lo
;
1925 mutex_lock(&loop_index_mutex
);
1928 ret
= loop_lookup(&lo
, parm
);
1933 ret
= loop_add(&lo
, parm
);
1935 case LOOP_CTL_REMOVE
:
1936 ret
= loop_lookup(&lo
, parm
);
1939 mutex_lock(&lo
->lo_ctl_mutex
);
1940 if (lo
->lo_state
!= Lo_unbound
) {
1942 mutex_unlock(&lo
->lo_ctl_mutex
);
1945 if (atomic_read(&lo
->lo_refcnt
) > 0) {
1947 mutex_unlock(&lo
->lo_ctl_mutex
);
1950 lo
->lo_disk
->private_data
= NULL
;
1951 mutex_unlock(&lo
->lo_ctl_mutex
);
1952 idr_remove(&loop_index_idr
, lo
->lo_number
);
1955 case LOOP_CTL_GET_FREE
:
1956 ret
= loop_lookup(&lo
, -1);
1959 ret
= loop_add(&lo
, -1);
1961 mutex_unlock(&loop_index_mutex
);
1966 static const struct file_operations loop_ctl_fops
= {
1967 .open
= nonseekable_open
,
1968 .unlocked_ioctl
= loop_control_ioctl
,
1969 .compat_ioctl
= loop_control_ioctl
,
1970 .owner
= THIS_MODULE
,
1971 .llseek
= noop_llseek
,
1974 static struct miscdevice loop_misc
= {
1975 .minor
= LOOP_CTRL_MINOR
,
1976 .name
= "loop-control",
1977 .fops
= &loop_ctl_fops
,
1980 MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR
);
1981 MODULE_ALIAS("devname:loop-control");
1983 static int __init
loop_init(void)
1986 unsigned long range
;
1987 struct loop_device
*lo
;
1990 err
= misc_register(&loop_misc
);
1996 part_shift
= fls(max_part
);
1999 * Adjust max_part according to part_shift as it is exported
2000 * to user space so that user can decide correct minor number
2001 * if [s]he want to create more devices.
2003 * Note that -1 is required because partition 0 is reserved
2004 * for the whole disk.
2006 max_part
= (1UL << part_shift
) - 1;
2009 if ((1UL << part_shift
) > DISK_MAX_PARTS
) {
2014 if (max_loop
> 1UL << (MINORBITS
- part_shift
)) {
2020 * If max_loop is specified, create that many devices upfront.
2021 * This also becomes a hard limit. If max_loop is not specified,
2022 * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
2023 * init time. Loop devices can be requested on-demand with the
2024 * /dev/loop-control interface, or be instantiated by accessing
2025 * a 'dead' device node.
2029 range
= max_loop
<< part_shift
;
2031 nr
= CONFIG_BLK_DEV_LOOP_MIN_COUNT
;
2032 range
= 1UL << MINORBITS
;
2035 if (register_blkdev(LOOP_MAJOR
, "loop")) {
2040 blk_register_region(MKDEV(LOOP_MAJOR
, 0), range
,
2041 THIS_MODULE
, loop_probe
, NULL
, NULL
);
2043 /* pre-create number of devices given by config or max_loop */
2044 mutex_lock(&loop_index_mutex
);
2045 for (i
= 0; i
< nr
; i
++)
2047 mutex_unlock(&loop_index_mutex
);
2049 printk(KERN_INFO
"loop: module loaded\n");
2053 misc_deregister(&loop_misc
);
2057 static int loop_exit_cb(int id
, void *ptr
, void *data
)
2059 struct loop_device
*lo
= ptr
;
2065 static void __exit
loop_exit(void)
2067 unsigned long range
;
2069 range
= max_loop
? max_loop
<< part_shift
: 1UL << MINORBITS
;
2071 idr_for_each(&loop_index_idr
, &loop_exit_cb
, NULL
);
2072 idr_destroy(&loop_index_idr
);
2074 blk_unregister_region(MKDEV(LOOP_MAJOR
, 0), range
);
2075 unregister_blkdev(LOOP_MAJOR
, "loop");
2077 misc_deregister(&loop_misc
);
2080 module_init(loop_init
);
2081 module_exit(loop_exit
);
2084 static int __init
max_loop_setup(char *str
)
2086 max_loop
= simple_strtol(str
, NULL
, 0);
2090 __setup("max_loop=", max_loop_setup
);