CIFS: Fix endian conversion of vcnum field
[linux-2.6/mini2440.git] / drivers / block / loop.c
blobbf034557767243ecbb0fd3c56538f7877e222345
1 /*
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
36 * Al Viro too.
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
46 * Still To Fix:
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>
55 #include <linux/fs.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/smp_lock.h>
65 #include <linux/swap.h>
66 #include <linux/slab.h>
67 #include <linux/loop.h>
68 #include <linux/compat.h>
69 #include <linux/suspend.h>
70 #include <linux/freezer.h>
71 #include <linux/writeback.h>
72 #include <linux/buffer_head.h> /* for invalidate_bdev() */
73 #include <linux/completion.h>
74 #include <linux/highmem.h>
75 #include <linux/gfp.h>
76 #include <linux/kthread.h>
77 #include <linux/splice.h>
79 #include <asm/uaccess.h>
81 static LIST_HEAD(loop_devices);
82 static DEFINE_MUTEX(loop_devices_mutex);
84 static int max_part;
85 static int part_shift;
88 * Transfer functions
90 static int transfer_none(struct loop_device *lo, int cmd,
91 struct page *raw_page, unsigned raw_off,
92 struct page *loop_page, unsigned loop_off,
93 int size, sector_t real_block)
95 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
96 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
98 if (cmd == READ)
99 memcpy(loop_buf, raw_buf, size);
100 else
101 memcpy(raw_buf, loop_buf, size);
103 kunmap_atomic(raw_buf, KM_USER0);
104 kunmap_atomic(loop_buf, KM_USER1);
105 cond_resched();
106 return 0;
109 static int transfer_xor(struct loop_device *lo, int cmd,
110 struct page *raw_page, unsigned raw_off,
111 struct page *loop_page, unsigned loop_off,
112 int size, sector_t real_block)
114 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
115 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
116 char *in, *out, *key;
117 int i, keysize;
119 if (cmd == READ) {
120 in = raw_buf;
121 out = loop_buf;
122 } else {
123 in = loop_buf;
124 out = raw_buf;
127 key = lo->lo_encrypt_key;
128 keysize = lo->lo_encrypt_key_size;
129 for (i = 0; i < size; i++)
130 *out++ = *in++ ^ key[(i & 511) % keysize];
132 kunmap_atomic(raw_buf, KM_USER0);
133 kunmap_atomic(loop_buf, KM_USER1);
134 cond_resched();
135 return 0;
138 static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140 if (unlikely(info->lo_encrypt_key_size <= 0))
141 return -EINVAL;
142 return 0;
145 static struct loop_func_table none_funcs = {
146 .number = LO_CRYPT_NONE,
147 .transfer = transfer_none,
150 static struct loop_func_table xor_funcs = {
151 .number = LO_CRYPT_XOR,
152 .transfer = transfer_xor,
153 .init = xor_init
156 /* xfer_funcs[0] is special - its release function is never called */
157 static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
158 &none_funcs,
159 &xor_funcs
162 static loff_t get_loop_size(struct loop_device *lo, struct file *file)
164 loff_t size, offset, loopsize;
166 /* Compute loopsize in bytes */
167 size = i_size_read(file->f_mapping->host);
168 offset = lo->lo_offset;
169 loopsize = size - offset;
170 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
171 loopsize = lo->lo_sizelimit;
174 * Unfortunately, if we want to do I/O on the device,
175 * the number of 512-byte sectors has to fit into a sector_t.
177 return loopsize >> 9;
180 static int
181 figure_loop_size(struct loop_device *lo)
183 loff_t size = get_loop_size(lo, lo->lo_backing_file);
184 sector_t x = (sector_t)size;
186 if (unlikely((loff_t)x != size))
187 return -EFBIG;
189 set_capacity(lo->lo_disk, x);
190 return 0;
193 static inline int
194 lo_do_transfer(struct loop_device *lo, int cmd,
195 struct page *rpage, unsigned roffs,
196 struct page *lpage, unsigned loffs,
197 int size, sector_t rblock)
199 if (unlikely(!lo->transfer))
200 return 0;
202 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
206 * do_lo_send_aops - helper for writing data to a loop device
208 * This is the fast version for backing filesystems which implement the address
209 * space operations write_begin and write_end.
211 static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
212 loff_t pos, struct page *unused)
214 struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
215 struct address_space *mapping = file->f_mapping;
216 pgoff_t index;
217 unsigned offset, bv_offs;
218 int len, ret;
220 mutex_lock(&mapping->host->i_mutex);
221 index = pos >> PAGE_CACHE_SHIFT;
222 offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
223 bv_offs = bvec->bv_offset;
224 len = bvec->bv_len;
225 while (len > 0) {
226 sector_t IV;
227 unsigned size, copied;
228 int transfer_result;
229 struct page *page;
230 void *fsdata;
232 IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
233 size = PAGE_CACHE_SIZE - offset;
234 if (size > len)
235 size = len;
237 ret = pagecache_write_begin(file, mapping, pos, size, 0,
238 &page, &fsdata);
239 if (ret)
240 goto fail;
242 transfer_result = lo_do_transfer(lo, WRITE, page, offset,
243 bvec->bv_page, bv_offs, size, IV);
244 copied = size;
245 if (unlikely(transfer_result))
246 copied = 0;
248 ret = pagecache_write_end(file, mapping, pos, size, copied,
249 page, fsdata);
250 if (ret < 0 || ret != copied)
251 goto fail;
253 if (unlikely(transfer_result))
254 goto fail;
256 bv_offs += copied;
257 len -= copied;
258 offset = 0;
259 index++;
260 pos += copied;
262 ret = 0;
263 out:
264 mutex_unlock(&mapping->host->i_mutex);
265 return ret;
266 fail:
267 ret = -1;
268 goto out;
272 * __do_lo_send_write - helper for writing data to a loop device
274 * This helper just factors out common code between do_lo_send_direct_write()
275 * and do_lo_send_write().
277 static int __do_lo_send_write(struct file *file,
278 u8 *buf, const int len, loff_t pos)
280 ssize_t bw;
281 mm_segment_t old_fs = get_fs();
283 set_fs(get_ds());
284 bw = file->f_op->write(file, buf, len, &pos);
285 set_fs(old_fs);
286 if (likely(bw == len))
287 return 0;
288 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
289 (unsigned long long)pos, len);
290 if (bw >= 0)
291 bw = -EIO;
292 return bw;
296 * do_lo_send_direct_write - helper for writing data to a loop device
298 * This is the fast, non-transforming version for backing filesystems which do
299 * not implement the address space operations write_begin and write_end.
300 * It uses the write file operation which should be present on all writeable
301 * filesystems.
303 static int do_lo_send_direct_write(struct loop_device *lo,
304 struct bio_vec *bvec, loff_t pos, struct page *page)
306 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
307 kmap(bvec->bv_page) + bvec->bv_offset,
308 bvec->bv_len, pos);
309 kunmap(bvec->bv_page);
310 cond_resched();
311 return bw;
315 * do_lo_send_write - helper for writing data to a loop device
317 * This is the slow, transforming version for filesystems which do not
318 * implement the address space operations write_begin and write_end. It
319 * uses the write file operation which should be present on all writeable
320 * filesystems.
322 * Using fops->write is slower than using aops->{prepare,commit}_write in the
323 * transforming case because we need to double buffer the data as we cannot do
324 * the transformations in place as we do not have direct access to the
325 * destination pages of the backing file.
327 static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
328 loff_t pos, struct page *page)
330 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
331 bvec->bv_offset, bvec->bv_len, pos >> 9);
332 if (likely(!ret))
333 return __do_lo_send_write(lo->lo_backing_file,
334 page_address(page), bvec->bv_len,
335 pos);
336 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
337 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
338 if (ret > 0)
339 ret = -EIO;
340 return ret;
343 static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
345 int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
346 struct page *page);
347 struct bio_vec *bvec;
348 struct page *page = NULL;
349 int i, ret = 0;
351 do_lo_send = do_lo_send_aops;
352 if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
353 do_lo_send = do_lo_send_direct_write;
354 if (lo->transfer != transfer_none) {
355 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
356 if (unlikely(!page))
357 goto fail;
358 kmap(page);
359 do_lo_send = do_lo_send_write;
362 bio_for_each_segment(bvec, bio, i) {
363 ret = do_lo_send(lo, bvec, pos, page);
364 if (ret < 0)
365 break;
366 pos += bvec->bv_len;
368 if (page) {
369 kunmap(page);
370 __free_page(page);
372 out:
373 return ret;
374 fail:
375 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
376 ret = -ENOMEM;
377 goto out;
380 struct lo_read_data {
381 struct loop_device *lo;
382 struct page *page;
383 unsigned offset;
384 int bsize;
387 static int
388 lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
389 struct splice_desc *sd)
391 struct lo_read_data *p = sd->u.data;
392 struct loop_device *lo = p->lo;
393 struct page *page = buf->page;
394 sector_t IV;
395 int size, ret;
397 ret = buf->ops->confirm(pipe, buf);
398 if (unlikely(ret))
399 return ret;
401 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
402 (buf->offset >> 9);
403 size = sd->len;
404 if (size > p->bsize)
405 size = p->bsize;
407 if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
408 printk(KERN_ERR "loop: transfer error block %ld\n",
409 page->index);
410 size = -EINVAL;
413 flush_dcache_page(p->page);
415 if (size > 0)
416 p->offset += size;
418 return size;
421 static int
422 lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
424 return __splice_from_pipe(pipe, sd, lo_splice_actor);
427 static int
428 do_lo_receive(struct loop_device *lo,
429 struct bio_vec *bvec, int bsize, loff_t pos)
431 struct lo_read_data cookie;
432 struct splice_desc sd;
433 struct file *file;
434 long retval;
436 cookie.lo = lo;
437 cookie.page = bvec->bv_page;
438 cookie.offset = bvec->bv_offset;
439 cookie.bsize = bsize;
441 sd.len = 0;
442 sd.total_len = bvec->bv_len;
443 sd.flags = 0;
444 sd.pos = pos;
445 sd.u.data = &cookie;
447 file = lo->lo_backing_file;
448 retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
450 if (retval < 0)
451 return retval;
453 return 0;
456 static int
457 lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
459 struct bio_vec *bvec;
460 int i, ret = 0;
462 bio_for_each_segment(bvec, bio, i) {
463 ret = do_lo_receive(lo, bvec, bsize, pos);
464 if (ret < 0)
465 break;
466 pos += bvec->bv_len;
468 return ret;
471 static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
473 loff_t pos;
474 int ret;
476 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
477 if (bio_rw(bio) == WRITE)
478 ret = lo_send(lo, bio, pos);
479 else
480 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
481 return ret;
485 * Add bio to back of pending list
487 static void loop_add_bio(struct loop_device *lo, struct bio *bio)
489 if (lo->lo_biotail) {
490 lo->lo_biotail->bi_next = bio;
491 lo->lo_biotail = bio;
492 } else
493 lo->lo_bio = lo->lo_biotail = bio;
497 * Grab first pending buffer
499 static struct bio *loop_get_bio(struct loop_device *lo)
501 struct bio *bio;
503 if ((bio = lo->lo_bio)) {
504 if (bio == lo->lo_biotail)
505 lo->lo_biotail = NULL;
506 lo->lo_bio = bio->bi_next;
507 bio->bi_next = NULL;
510 return bio;
513 static int loop_make_request(struct request_queue *q, struct bio *old_bio)
515 struct loop_device *lo = q->queuedata;
516 int rw = bio_rw(old_bio);
518 if (rw == READA)
519 rw = READ;
521 BUG_ON(!lo || (rw != READ && rw != WRITE));
523 spin_lock_irq(&lo->lo_lock);
524 if (lo->lo_state != Lo_bound)
525 goto out;
526 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
527 goto out;
528 loop_add_bio(lo, old_bio);
529 wake_up(&lo->lo_event);
530 spin_unlock_irq(&lo->lo_lock);
531 return 0;
533 out:
534 spin_unlock_irq(&lo->lo_lock);
535 bio_io_error(old_bio);
536 return 0;
540 * kick off io on the underlying address space
542 static void loop_unplug(struct request_queue *q)
544 struct loop_device *lo = q->queuedata;
546 queue_flag_clear_unlocked(QUEUE_FLAG_PLUGGED, q);
547 blk_run_address_space(lo->lo_backing_file->f_mapping);
550 struct switch_request {
551 struct file *file;
552 struct completion wait;
555 static void do_loop_switch(struct loop_device *, struct switch_request *);
557 static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
559 if (unlikely(!bio->bi_bdev)) {
560 do_loop_switch(lo, bio->bi_private);
561 bio_put(bio);
562 } else {
563 int ret = do_bio_filebacked(lo, bio);
564 bio_endio(bio, ret);
569 * worker thread that handles reads/writes to file backed loop devices,
570 * to avoid blocking in our make_request_fn. it also does loop decrypting
571 * on reads for block backed loop, as that is too heavy to do from
572 * b_end_io context where irqs may be disabled.
574 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
575 * calling kthread_stop(). Therefore once kthread_should_stop() is
576 * true, make_request will not place any more requests. Therefore
577 * once kthread_should_stop() is true and lo_bio is NULL, we are
578 * done with the loop.
580 static int loop_thread(void *data)
582 struct loop_device *lo = data;
583 struct bio *bio;
585 set_user_nice(current, -20);
587 while (!kthread_should_stop() || lo->lo_bio) {
589 wait_event_interruptible(lo->lo_event,
590 lo->lo_bio || kthread_should_stop());
592 if (!lo->lo_bio)
593 continue;
594 spin_lock_irq(&lo->lo_lock);
595 bio = loop_get_bio(lo);
596 spin_unlock_irq(&lo->lo_lock);
598 BUG_ON(!bio);
599 loop_handle_bio(lo, bio);
602 return 0;
606 * loop_switch performs the hard work of switching a backing store.
607 * First it needs to flush existing IO, it does this by sending a magic
608 * BIO down the pipe. The completion of this BIO does the actual switch.
610 static int loop_switch(struct loop_device *lo, struct file *file)
612 struct switch_request w;
613 struct bio *bio = bio_alloc(GFP_KERNEL, 0);
614 if (!bio)
615 return -ENOMEM;
616 init_completion(&w.wait);
617 w.file = file;
618 bio->bi_private = &w;
619 bio->bi_bdev = NULL;
620 loop_make_request(lo->lo_queue, bio);
621 wait_for_completion(&w.wait);
622 return 0;
626 * Helper to flush the IOs in loop, but keeping loop thread running
628 static int loop_flush(struct loop_device *lo)
630 /* loop not yet configured, no running thread, nothing to flush */
631 if (!lo->lo_thread)
632 return 0;
634 return loop_switch(lo, NULL);
638 * Do the actual switch; called from the BIO completion routine
640 static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
642 struct file *file = p->file;
643 struct file *old_file = lo->lo_backing_file;
644 struct address_space *mapping;
646 /* if no new file, only flush of queued bios requested */
647 if (!file)
648 goto out;
650 mapping = file->f_mapping;
651 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
652 lo->lo_backing_file = file;
653 lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
654 mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
655 lo->old_gfp_mask = mapping_gfp_mask(mapping);
656 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
657 out:
658 complete(&p->wait);
663 * loop_change_fd switched the backing store of a loopback device to
664 * a new file. This is useful for operating system installers to free up
665 * the original file and in High Availability environments to switch to
666 * an alternative location for the content in case of server meltdown.
667 * This can only work if the loop device is used read-only, and if the
668 * new backing store is the same size and type as the old backing store.
670 static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
671 unsigned int arg)
673 struct file *file, *old_file;
674 struct inode *inode;
675 int error;
677 error = -ENXIO;
678 if (lo->lo_state != Lo_bound)
679 goto out;
681 /* the loop device has to be read-only */
682 error = -EINVAL;
683 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
684 goto out;
686 error = -EBADF;
687 file = fget(arg);
688 if (!file)
689 goto out;
691 inode = file->f_mapping->host;
692 old_file = lo->lo_backing_file;
694 error = -EINVAL;
696 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
697 goto out_putf;
699 /* new backing store needs to support loop (eg splice_read) */
700 if (!inode->i_fop->splice_read)
701 goto out_putf;
703 /* size of the new backing store needs to be the same */
704 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
705 goto out_putf;
707 /* and ... switch */
708 error = loop_switch(lo, file);
709 if (error)
710 goto out_putf;
712 fput(old_file);
713 if (max_part > 0)
714 ioctl_by_bdev(bdev, BLKRRPART, 0);
715 return 0;
717 out_putf:
718 fput(file);
719 out:
720 return error;
723 static inline int is_loop_device(struct file *file)
725 struct inode *i = file->f_mapping->host;
727 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
730 static int loop_set_fd(struct loop_device *lo, fmode_t mode,
731 struct block_device *bdev, unsigned int arg)
733 struct file *file, *f;
734 struct inode *inode;
735 struct address_space *mapping;
736 unsigned lo_blocksize;
737 int lo_flags = 0;
738 int error;
739 loff_t size;
741 /* This is safe, since we have a reference from open(). */
742 __module_get(THIS_MODULE);
744 error = -EBADF;
745 file = fget(arg);
746 if (!file)
747 goto out;
749 error = -EBUSY;
750 if (lo->lo_state != Lo_unbound)
751 goto out_putf;
753 /* Avoid recursion */
754 f = file;
755 while (is_loop_device(f)) {
756 struct loop_device *l;
758 if (f->f_mapping->host->i_bdev == bdev)
759 goto out_putf;
761 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
762 if (l->lo_state == Lo_unbound) {
763 error = -EINVAL;
764 goto out_putf;
766 f = l->lo_backing_file;
769 mapping = file->f_mapping;
770 inode = mapping->host;
772 if (!(file->f_mode & FMODE_WRITE))
773 lo_flags |= LO_FLAGS_READ_ONLY;
775 error = -EINVAL;
776 if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
777 const struct address_space_operations *aops = mapping->a_ops;
779 * If we can't read - sorry. If we only can't write - well,
780 * it's going to be read-only.
782 if (!file->f_op->splice_read)
783 goto out_putf;
784 if (aops->write_begin)
785 lo_flags |= LO_FLAGS_USE_AOPS;
786 if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
787 lo_flags |= LO_FLAGS_READ_ONLY;
789 lo_blocksize = S_ISBLK(inode->i_mode) ?
790 inode->i_bdev->bd_block_size : PAGE_SIZE;
792 error = 0;
793 } else {
794 goto out_putf;
797 size = get_loop_size(lo, file);
799 if ((loff_t)(sector_t)size != size) {
800 error = -EFBIG;
801 goto out_putf;
804 if (!(mode & FMODE_WRITE))
805 lo_flags |= LO_FLAGS_READ_ONLY;
807 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
809 lo->lo_blocksize = lo_blocksize;
810 lo->lo_device = bdev;
811 lo->lo_flags = lo_flags;
812 lo->lo_backing_file = file;
813 lo->transfer = transfer_none;
814 lo->ioctl = NULL;
815 lo->lo_sizelimit = 0;
816 lo->old_gfp_mask = mapping_gfp_mask(mapping);
817 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
819 lo->lo_bio = lo->lo_biotail = NULL;
822 * set queue make_request_fn, and add limits based on lower level
823 * device
825 blk_queue_make_request(lo->lo_queue, loop_make_request);
826 lo->lo_queue->queuedata = lo;
827 lo->lo_queue->unplug_fn = loop_unplug;
829 set_capacity(lo->lo_disk, size);
830 bd_set_size(bdev, size << 9);
832 set_blocksize(bdev, lo_blocksize);
834 lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
835 lo->lo_number);
836 if (IS_ERR(lo->lo_thread)) {
837 error = PTR_ERR(lo->lo_thread);
838 goto out_clr;
840 lo->lo_state = Lo_bound;
841 wake_up_process(lo->lo_thread);
842 if (max_part > 0)
843 ioctl_by_bdev(bdev, BLKRRPART, 0);
844 return 0;
846 out_clr:
847 lo->lo_thread = NULL;
848 lo->lo_device = NULL;
849 lo->lo_backing_file = NULL;
850 lo->lo_flags = 0;
851 set_capacity(lo->lo_disk, 0);
852 invalidate_bdev(bdev);
853 bd_set_size(bdev, 0);
854 mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
855 lo->lo_state = Lo_unbound;
856 out_putf:
857 fput(file);
858 out:
859 /* This is safe: open() is still holding a reference. */
860 module_put(THIS_MODULE);
861 return error;
864 static int
865 loop_release_xfer(struct loop_device *lo)
867 int err = 0;
868 struct loop_func_table *xfer = lo->lo_encryption;
870 if (xfer) {
871 if (xfer->release)
872 err = xfer->release(lo);
873 lo->transfer = NULL;
874 lo->lo_encryption = NULL;
875 module_put(xfer->owner);
877 return err;
880 static int
881 loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
882 const struct loop_info64 *i)
884 int err = 0;
886 if (xfer) {
887 struct module *owner = xfer->owner;
889 if (!try_module_get(owner))
890 return -EINVAL;
891 if (xfer->init)
892 err = xfer->init(lo, i);
893 if (err)
894 module_put(owner);
895 else
896 lo->lo_encryption = xfer;
898 return err;
901 static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
903 struct file *filp = lo->lo_backing_file;
904 gfp_t gfp = lo->old_gfp_mask;
906 if (lo->lo_state != Lo_bound)
907 return -ENXIO;
909 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
910 return -EBUSY;
912 if (filp == NULL)
913 return -EINVAL;
915 spin_lock_irq(&lo->lo_lock);
916 lo->lo_state = Lo_rundown;
917 spin_unlock_irq(&lo->lo_lock);
919 kthread_stop(lo->lo_thread);
921 lo->lo_queue->unplug_fn = NULL;
922 lo->lo_backing_file = NULL;
924 loop_release_xfer(lo);
925 lo->transfer = NULL;
926 lo->ioctl = NULL;
927 lo->lo_device = NULL;
928 lo->lo_encryption = NULL;
929 lo->lo_offset = 0;
930 lo->lo_sizelimit = 0;
931 lo->lo_encrypt_key_size = 0;
932 lo->lo_flags = 0;
933 lo->lo_thread = NULL;
934 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
935 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
936 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
937 if (bdev)
938 invalidate_bdev(bdev);
939 set_capacity(lo->lo_disk, 0);
940 if (bdev)
941 bd_set_size(bdev, 0);
942 mapping_set_gfp_mask(filp->f_mapping, gfp);
943 lo->lo_state = Lo_unbound;
944 fput(filp);
945 /* This is safe: open() is still holding a reference. */
946 module_put(THIS_MODULE);
947 if (max_part > 0)
948 ioctl_by_bdev(bdev, BLKRRPART, 0);
949 return 0;
952 static int
953 loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
955 int err;
956 struct loop_func_table *xfer;
957 uid_t uid = current_uid();
959 if (lo->lo_encrypt_key_size &&
960 lo->lo_key_owner != uid &&
961 !capable(CAP_SYS_ADMIN))
962 return -EPERM;
963 if (lo->lo_state != Lo_bound)
964 return -ENXIO;
965 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
966 return -EINVAL;
968 err = loop_release_xfer(lo);
969 if (err)
970 return err;
972 if (info->lo_encrypt_type) {
973 unsigned int type = info->lo_encrypt_type;
975 if (type >= MAX_LO_CRYPT)
976 return -EINVAL;
977 xfer = xfer_funcs[type];
978 if (xfer == NULL)
979 return -EINVAL;
980 } else
981 xfer = NULL;
983 err = loop_init_xfer(lo, xfer, info);
984 if (err)
985 return err;
987 if (lo->lo_offset != info->lo_offset ||
988 lo->lo_sizelimit != info->lo_sizelimit) {
989 lo->lo_offset = info->lo_offset;
990 lo->lo_sizelimit = info->lo_sizelimit;
991 if (figure_loop_size(lo))
992 return -EFBIG;
995 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
996 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
997 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
998 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1000 if (!xfer)
1001 xfer = &none_funcs;
1002 lo->transfer = xfer->transfer;
1003 lo->ioctl = xfer->ioctl;
1005 if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1006 (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1007 lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1009 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1010 lo->lo_init[0] = info->lo_init[0];
1011 lo->lo_init[1] = info->lo_init[1];
1012 if (info->lo_encrypt_key_size) {
1013 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1014 info->lo_encrypt_key_size);
1015 lo->lo_key_owner = uid;
1018 return 0;
1021 static int
1022 loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1024 struct file *file = lo->lo_backing_file;
1025 struct kstat stat;
1026 int error;
1028 if (lo->lo_state != Lo_bound)
1029 return -ENXIO;
1030 error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1031 if (error)
1032 return error;
1033 memset(info, 0, sizeof(*info));
1034 info->lo_number = lo->lo_number;
1035 info->lo_device = huge_encode_dev(stat.dev);
1036 info->lo_inode = stat.ino;
1037 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1038 info->lo_offset = lo->lo_offset;
1039 info->lo_sizelimit = lo->lo_sizelimit;
1040 info->lo_flags = lo->lo_flags;
1041 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1042 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1043 info->lo_encrypt_type =
1044 lo->lo_encryption ? lo->lo_encryption->number : 0;
1045 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1046 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1047 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1048 lo->lo_encrypt_key_size);
1050 return 0;
1053 static void
1054 loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1056 memset(info64, 0, sizeof(*info64));
1057 info64->lo_number = info->lo_number;
1058 info64->lo_device = info->lo_device;
1059 info64->lo_inode = info->lo_inode;
1060 info64->lo_rdevice = info->lo_rdevice;
1061 info64->lo_offset = info->lo_offset;
1062 info64->lo_sizelimit = 0;
1063 info64->lo_encrypt_type = info->lo_encrypt_type;
1064 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1065 info64->lo_flags = info->lo_flags;
1066 info64->lo_init[0] = info->lo_init[0];
1067 info64->lo_init[1] = info->lo_init[1];
1068 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1069 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1070 else
1071 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1072 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1075 static int
1076 loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1078 memset(info, 0, sizeof(*info));
1079 info->lo_number = info64->lo_number;
1080 info->lo_device = info64->lo_device;
1081 info->lo_inode = info64->lo_inode;
1082 info->lo_rdevice = info64->lo_rdevice;
1083 info->lo_offset = info64->lo_offset;
1084 info->lo_encrypt_type = info64->lo_encrypt_type;
1085 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1086 info->lo_flags = info64->lo_flags;
1087 info->lo_init[0] = info64->lo_init[0];
1088 info->lo_init[1] = info64->lo_init[1];
1089 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1090 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1091 else
1092 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1093 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1095 /* error in case values were truncated */
1096 if (info->lo_device != info64->lo_device ||
1097 info->lo_rdevice != info64->lo_rdevice ||
1098 info->lo_inode != info64->lo_inode ||
1099 info->lo_offset != info64->lo_offset)
1100 return -EOVERFLOW;
1102 return 0;
1105 static int
1106 loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1108 struct loop_info info;
1109 struct loop_info64 info64;
1111 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1112 return -EFAULT;
1113 loop_info64_from_old(&info, &info64);
1114 return loop_set_status(lo, &info64);
1117 static int
1118 loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1120 struct loop_info64 info64;
1122 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1123 return -EFAULT;
1124 return loop_set_status(lo, &info64);
1127 static int
1128 loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1129 struct loop_info info;
1130 struct loop_info64 info64;
1131 int err = 0;
1133 if (!arg)
1134 err = -EINVAL;
1135 if (!err)
1136 err = loop_get_status(lo, &info64);
1137 if (!err)
1138 err = loop_info64_to_old(&info64, &info);
1139 if (!err && copy_to_user(arg, &info, sizeof(info)))
1140 err = -EFAULT;
1142 return err;
1145 static int
1146 loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1147 struct loop_info64 info64;
1148 int err = 0;
1150 if (!arg)
1151 err = -EINVAL;
1152 if (!err)
1153 err = loop_get_status(lo, &info64);
1154 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1155 err = -EFAULT;
1157 return err;
1160 static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1161 unsigned int cmd, unsigned long arg)
1163 struct loop_device *lo = bdev->bd_disk->private_data;
1164 int err;
1166 mutex_lock(&lo->lo_ctl_mutex);
1167 switch (cmd) {
1168 case LOOP_SET_FD:
1169 err = loop_set_fd(lo, mode, bdev, arg);
1170 break;
1171 case LOOP_CHANGE_FD:
1172 err = loop_change_fd(lo, bdev, arg);
1173 break;
1174 case LOOP_CLR_FD:
1175 err = loop_clr_fd(lo, bdev);
1176 break;
1177 case LOOP_SET_STATUS:
1178 err = loop_set_status_old(lo, (struct loop_info __user *) arg);
1179 break;
1180 case LOOP_GET_STATUS:
1181 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1182 break;
1183 case LOOP_SET_STATUS64:
1184 err = loop_set_status64(lo, (struct loop_info64 __user *) arg);
1185 break;
1186 case LOOP_GET_STATUS64:
1187 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1188 break;
1189 default:
1190 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1192 mutex_unlock(&lo->lo_ctl_mutex);
1193 return err;
1196 #ifdef CONFIG_COMPAT
1197 struct compat_loop_info {
1198 compat_int_t lo_number; /* ioctl r/o */
1199 compat_dev_t lo_device; /* ioctl r/o */
1200 compat_ulong_t lo_inode; /* ioctl r/o */
1201 compat_dev_t lo_rdevice; /* ioctl r/o */
1202 compat_int_t lo_offset;
1203 compat_int_t lo_encrypt_type;
1204 compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1205 compat_int_t lo_flags; /* ioctl r/o */
1206 char lo_name[LO_NAME_SIZE];
1207 unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1208 compat_ulong_t lo_init[2];
1209 char reserved[4];
1213 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1214 * - noinlined to reduce stack space usage in main part of driver
1216 static noinline int
1217 loop_info64_from_compat(const struct compat_loop_info __user *arg,
1218 struct loop_info64 *info64)
1220 struct compat_loop_info info;
1222 if (copy_from_user(&info, arg, sizeof(info)))
1223 return -EFAULT;
1225 memset(info64, 0, sizeof(*info64));
1226 info64->lo_number = info.lo_number;
1227 info64->lo_device = info.lo_device;
1228 info64->lo_inode = info.lo_inode;
1229 info64->lo_rdevice = info.lo_rdevice;
1230 info64->lo_offset = info.lo_offset;
1231 info64->lo_sizelimit = 0;
1232 info64->lo_encrypt_type = info.lo_encrypt_type;
1233 info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1234 info64->lo_flags = info.lo_flags;
1235 info64->lo_init[0] = info.lo_init[0];
1236 info64->lo_init[1] = info.lo_init[1];
1237 if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1238 memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1239 else
1240 memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1241 memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1242 return 0;
1246 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1247 * - noinlined to reduce stack space usage in main part of driver
1249 static noinline int
1250 loop_info64_to_compat(const struct loop_info64 *info64,
1251 struct compat_loop_info __user *arg)
1253 struct compat_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);
1268 else
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 ||
1277 info.lo_init[0] != info64->lo_init[0] ||
1278 info.lo_init[1] != info64->lo_init[1])
1279 return -EOVERFLOW;
1281 if (copy_to_user(arg, &info, sizeof(info)))
1282 return -EFAULT;
1283 return 0;
1286 static int
1287 loop_set_status_compat(struct loop_device *lo,
1288 const struct compat_loop_info __user *arg)
1290 struct loop_info64 info64;
1291 int ret;
1293 ret = loop_info64_from_compat(arg, &info64);
1294 if (ret < 0)
1295 return ret;
1296 return loop_set_status(lo, &info64);
1299 static int
1300 loop_get_status_compat(struct loop_device *lo,
1301 struct compat_loop_info __user *arg)
1303 struct loop_info64 info64;
1304 int err = 0;
1306 if (!arg)
1307 err = -EINVAL;
1308 if (!err)
1309 err = loop_get_status(lo, &info64);
1310 if (!err)
1311 err = loop_info64_to_compat(&info64, arg);
1312 return err;
1315 static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1316 unsigned int cmd, unsigned long arg)
1318 struct loop_device *lo = bdev->bd_disk->private_data;
1319 int err;
1321 switch(cmd) {
1322 case LOOP_SET_STATUS:
1323 mutex_lock(&lo->lo_ctl_mutex);
1324 err = loop_set_status_compat(
1325 lo, (const struct compat_loop_info __user *) arg);
1326 mutex_unlock(&lo->lo_ctl_mutex);
1327 break;
1328 case LOOP_GET_STATUS:
1329 mutex_lock(&lo->lo_ctl_mutex);
1330 err = loop_get_status_compat(
1331 lo, (struct compat_loop_info __user *) arg);
1332 mutex_unlock(&lo->lo_ctl_mutex);
1333 break;
1334 case LOOP_CLR_FD:
1335 case LOOP_GET_STATUS64:
1336 case LOOP_SET_STATUS64:
1337 arg = (unsigned long) compat_ptr(arg);
1338 case LOOP_SET_FD:
1339 case LOOP_CHANGE_FD:
1340 err = lo_ioctl(bdev, mode, cmd, arg);
1341 break;
1342 default:
1343 err = -ENOIOCTLCMD;
1344 break;
1346 return err;
1348 #endif
1350 static int lo_open(struct block_device *bdev, fmode_t mode)
1352 struct loop_device *lo = bdev->bd_disk->private_data;
1354 mutex_lock(&lo->lo_ctl_mutex);
1355 lo->lo_refcnt++;
1356 mutex_unlock(&lo->lo_ctl_mutex);
1358 return 0;
1361 static int lo_release(struct gendisk *disk, fmode_t mode)
1363 struct loop_device *lo = disk->private_data;
1365 mutex_lock(&lo->lo_ctl_mutex);
1367 if (--lo->lo_refcnt)
1368 goto out;
1370 if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1372 * In autoclear mode, stop the loop thread
1373 * and remove configuration after last close.
1375 loop_clr_fd(lo, NULL);
1376 } else {
1378 * Otherwise keep thread (if running) and config,
1379 * but flush possible ongoing bios in thread.
1381 loop_flush(lo);
1384 out:
1385 mutex_unlock(&lo->lo_ctl_mutex);
1387 return 0;
1390 static struct block_device_operations lo_fops = {
1391 .owner = THIS_MODULE,
1392 .open = lo_open,
1393 .release = lo_release,
1394 .ioctl = lo_ioctl,
1395 #ifdef CONFIG_COMPAT
1396 .compat_ioctl = lo_compat_ioctl,
1397 #endif
1401 * And now the modules code and kernel interface.
1403 static int max_loop;
1404 module_param(max_loop, int, 0);
1405 MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1406 module_param(max_part, int, 0);
1407 MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1408 MODULE_LICENSE("GPL");
1409 MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1411 int loop_register_transfer(struct loop_func_table *funcs)
1413 unsigned int n = funcs->number;
1415 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1416 return -EINVAL;
1417 xfer_funcs[n] = funcs;
1418 return 0;
1421 int loop_unregister_transfer(int number)
1423 unsigned int n = number;
1424 struct loop_device *lo;
1425 struct loop_func_table *xfer;
1427 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1428 return -EINVAL;
1430 xfer_funcs[n] = NULL;
1432 list_for_each_entry(lo, &loop_devices, lo_list) {
1433 mutex_lock(&lo->lo_ctl_mutex);
1435 if (lo->lo_encryption == xfer)
1436 loop_release_xfer(lo);
1438 mutex_unlock(&lo->lo_ctl_mutex);
1441 return 0;
1444 EXPORT_SYMBOL(loop_register_transfer);
1445 EXPORT_SYMBOL(loop_unregister_transfer);
1447 static struct loop_device *loop_alloc(int i)
1449 struct loop_device *lo;
1450 struct gendisk *disk;
1452 lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1453 if (!lo)
1454 goto out;
1456 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1457 if (!lo->lo_queue)
1458 goto out_free_dev;
1460 disk = lo->lo_disk = alloc_disk(1 << part_shift);
1461 if (!disk)
1462 goto out_free_queue;
1464 mutex_init(&lo->lo_ctl_mutex);
1465 lo->lo_number = i;
1466 lo->lo_thread = NULL;
1467 init_waitqueue_head(&lo->lo_event);
1468 spin_lock_init(&lo->lo_lock);
1469 disk->major = LOOP_MAJOR;
1470 disk->first_minor = i << part_shift;
1471 disk->fops = &lo_fops;
1472 disk->private_data = lo;
1473 disk->queue = lo->lo_queue;
1474 sprintf(disk->disk_name, "loop%d", i);
1475 return lo;
1477 out_free_queue:
1478 blk_cleanup_queue(lo->lo_queue);
1479 out_free_dev:
1480 kfree(lo);
1481 out:
1482 return NULL;
1485 static void loop_free(struct loop_device *lo)
1487 blk_cleanup_queue(lo->lo_queue);
1488 put_disk(lo->lo_disk);
1489 list_del(&lo->lo_list);
1490 kfree(lo);
1493 static struct loop_device *loop_init_one(int i)
1495 struct loop_device *lo;
1497 list_for_each_entry(lo, &loop_devices, lo_list) {
1498 if (lo->lo_number == i)
1499 return lo;
1502 lo = loop_alloc(i);
1503 if (lo) {
1504 add_disk(lo->lo_disk);
1505 list_add_tail(&lo->lo_list, &loop_devices);
1507 return lo;
1510 static void loop_del_one(struct loop_device *lo)
1512 del_gendisk(lo->lo_disk);
1513 loop_free(lo);
1516 static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1518 struct loop_device *lo;
1519 struct kobject *kobj;
1521 mutex_lock(&loop_devices_mutex);
1522 lo = loop_init_one(dev & MINORMASK);
1523 kobj = lo ? get_disk(lo->lo_disk) : ERR_PTR(-ENOMEM);
1524 mutex_unlock(&loop_devices_mutex);
1526 *part = 0;
1527 return kobj;
1530 static int __init loop_init(void)
1532 int i, nr;
1533 unsigned long range;
1534 struct loop_device *lo, *next;
1537 * loop module now has a feature to instantiate underlying device
1538 * structure on-demand, provided that there is an access dev node.
1539 * However, this will not work well with user space tool that doesn't
1540 * know about such "feature". In order to not break any existing
1541 * tool, we do the following:
1543 * (1) if max_loop is specified, create that many upfront, and this
1544 * also becomes a hard limit.
1545 * (2) if max_loop is not specified, create 8 loop device on module
1546 * load, user can further extend loop device by create dev node
1547 * themselves and have kernel automatically instantiate actual
1548 * device on-demand.
1551 part_shift = 0;
1552 if (max_part > 0)
1553 part_shift = fls(max_part);
1555 if (max_loop > 1UL << (MINORBITS - part_shift))
1556 return -EINVAL;
1558 if (max_loop) {
1559 nr = max_loop;
1560 range = max_loop;
1561 } else {
1562 nr = 8;
1563 range = 1UL << (MINORBITS - part_shift);
1566 if (register_blkdev(LOOP_MAJOR, "loop"))
1567 return -EIO;
1569 for (i = 0; i < nr; i++) {
1570 lo = loop_alloc(i);
1571 if (!lo)
1572 goto Enomem;
1573 list_add_tail(&lo->lo_list, &loop_devices);
1576 /* point of no return */
1578 list_for_each_entry(lo, &loop_devices, lo_list)
1579 add_disk(lo->lo_disk);
1581 blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1582 THIS_MODULE, loop_probe, NULL, NULL);
1584 printk(KERN_INFO "loop: module loaded\n");
1585 return 0;
1587 Enomem:
1588 printk(KERN_INFO "loop: out of memory\n");
1590 list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
1591 loop_free(lo);
1593 unregister_blkdev(LOOP_MAJOR, "loop");
1594 return -ENOMEM;
1597 static void __exit loop_exit(void)
1599 unsigned long range;
1600 struct loop_device *lo, *next;
1602 range = max_loop ? max_loop : 1UL << (MINORBITS - part_shift);
1604 list_for_each_entry_safe(lo, next, &loop_devices, lo_list)
1605 loop_del_one(lo);
1607 blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1608 unregister_blkdev(LOOP_MAJOR, "loop");
1611 module_init(loop_init);
1612 module_exit(loop_exit);
1614 #ifndef MODULE
1615 static int __init max_loop_setup(char *str)
1617 max_loop = simple_strtol(str, NULL, 0);
1618 return 1;
1621 __setup("max_loop=", max_loop_setup);
1622 #endif