blob: 7b3b94ddddccb4aaf5cab64e6e94923ab2fb6c49 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/drivers/block/loop.c
3 *
4 * Written by Theodore Ts'o, 3/29/93
5 *
6 * Copyright 1993 by Theodore Ts'o. Redistribution of this file is
7 * permitted under the GNU General Public License.
8 *
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
11 *
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
14 *
15 * Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
16 *
17 * Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
18 *
19 * Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
20 *
21 * Loadable modules and other fixes by AK, 1998
22 *
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
26 *
27 * Maximum number of loop devices now dynamic via max_loop module parameter.
28 * Russell Kroll <rkroll@exploits.org> 19990701
29 *
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
33 *
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
38 *
39 * Support up to 256 loop devices
40 * Heinz Mauelshagen <mge@sistina.com>, Feb 2002
41 *
42 * Support for falling back on the write file operation when the address space
43 * operations prepare_write and/or commit_write are not available on the
44 * backing filesystem.
45 * Anton Altaparmakov, 16 Feb 2005
46 *
47 * Still To Fix:
48 * - Advisory locking is ignored here.
49 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
50 *
51 */
52
Linus Torvalds1da177e2005-04-16 15:20:36 -070053#include <linux/module.h>
54#include <linux/moduleparam.h>
55#include <linux/sched.h>
56#include <linux/fs.h>
57#include <linux/file.h>
58#include <linux/stat.h>
59#include <linux/errno.h>
60#include <linux/major.h>
61#include <linux/wait.h>
62#include <linux/blkdev.h>
63#include <linux/blkpg.h>
64#include <linux/init.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070065#include <linux/smp_lock.h>
66#include <linux/swap.h>
67#include <linux/slab.h>
68#include <linux/loop.h>
69#include <linux/suspend.h>
70#include <linux/writeback.h>
71#include <linux/buffer_head.h> /* for invalidate_bdev() */
72#include <linux/completion.h>
73#include <linux/highmem.h>
74#include <linux/gfp.h>
75
76#include <asm/uaccess.h>
77
78static int max_loop = 8;
79static struct loop_device *loop_dev;
80static struct gendisk **disks;
81
82/*
83 * Transfer functions
84 */
85static int transfer_none(struct loop_device *lo, int cmd,
86 struct page *raw_page, unsigned raw_off,
87 struct page *loop_page, unsigned loop_off,
88 int size, sector_t real_block)
89{
90 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
91 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
92
93 if (cmd == READ)
94 memcpy(loop_buf, raw_buf, size);
95 else
96 memcpy(raw_buf, loop_buf, size);
97
98 kunmap_atomic(raw_buf, KM_USER0);
99 kunmap_atomic(loop_buf, KM_USER1);
100 cond_resched();
101 return 0;
102}
103
104static int transfer_xor(struct loop_device *lo, int cmd,
105 struct page *raw_page, unsigned raw_off,
106 struct page *loop_page, unsigned loop_off,
107 int size, sector_t real_block)
108{
109 char *raw_buf = kmap_atomic(raw_page, KM_USER0) + raw_off;
110 char *loop_buf = kmap_atomic(loop_page, KM_USER1) + loop_off;
111 char *in, *out, *key;
112 int i, keysize;
113
114 if (cmd == READ) {
115 in = raw_buf;
116 out = loop_buf;
117 } else {
118 in = loop_buf;
119 out = raw_buf;
120 }
121
122 key = lo->lo_encrypt_key;
123 keysize = lo->lo_encrypt_key_size;
124 for (i = 0; i < size; i++)
125 *out++ = *in++ ^ key[(i & 511) % keysize];
126
127 kunmap_atomic(raw_buf, KM_USER0);
128 kunmap_atomic(loop_buf, KM_USER1);
129 cond_resched();
130 return 0;
131}
132
133static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
134{
135 if (unlikely(info->lo_encrypt_key_size <= 0))
136 return -EINVAL;
137 return 0;
138}
139
140static struct loop_func_table none_funcs = {
141 .number = LO_CRYPT_NONE,
142 .transfer = transfer_none,
143};
144
145static struct loop_func_table xor_funcs = {
146 .number = LO_CRYPT_XOR,
147 .transfer = transfer_xor,
148 .init = xor_init
149};
150
151/* xfer_funcs[0] is special - its release function is never called */
152static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
153 &none_funcs,
154 &xor_funcs
155};
156
157static loff_t get_loop_size(struct loop_device *lo, struct file *file)
158{
159 loff_t size, offset, loopsize;
160
161 /* Compute loopsize in bytes */
162 size = i_size_read(file->f_mapping->host);
163 offset = lo->lo_offset;
164 loopsize = size - offset;
165 if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
166 loopsize = lo->lo_sizelimit;
167
168 /*
169 * Unfortunately, if we want to do I/O on the device,
170 * the number of 512-byte sectors has to fit into a sector_t.
171 */
172 return loopsize >> 9;
173}
174
175static int
176figure_loop_size(struct loop_device *lo)
177{
178 loff_t size = get_loop_size(lo, lo->lo_backing_file);
179 sector_t x = (sector_t)size;
180
181 if (unlikely((loff_t)x != size))
182 return -EFBIG;
183
184 set_capacity(disks[lo->lo_number], x);
185 return 0;
186}
187
188static inline int
189lo_do_transfer(struct loop_device *lo, int cmd,
190 struct page *rpage, unsigned roffs,
191 struct page *lpage, unsigned loffs,
192 int size, sector_t rblock)
193{
194 if (unlikely(!lo->transfer))
195 return 0;
196
197 return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
198}
199
200/**
201 * do_lo_send_aops - helper for writing data to a loop device
202 *
203 * This is the fast version for backing filesystems which implement the address
204 * space operations prepare_write and commit_write.
205 */
206static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
207 int bsize, loff_t pos, struct page *page)
208{
209 struct file *file = lo->lo_backing_file; /* kudos to NFsckingS */
210 struct address_space *mapping = file->f_mapping;
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700211 const struct address_space_operations *aops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 pgoff_t index;
213 unsigned offset, bv_offs;
Zach Brown994fc28c2005-12-15 14:28:17 -0800214 int len, ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800216 mutex_lock(&mapping->host->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 index = pos >> PAGE_CACHE_SHIFT;
218 offset = pos & ((pgoff_t)PAGE_CACHE_SIZE - 1);
219 bv_offs = bvec->bv_offset;
220 len = bvec->bv_len;
221 while (len > 0) {
222 sector_t IV;
223 unsigned size;
224 int transfer_result;
225
226 IV = ((sector_t)index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
227 size = PAGE_CACHE_SIZE - offset;
228 if (size > len)
229 size = len;
230 page = grab_cache_page(mapping, index);
231 if (unlikely(!page))
232 goto fail;
Zach Brown994fc28c2005-12-15 14:28:17 -0800233 ret = aops->prepare_write(file, page, offset,
234 offset + size);
235 if (unlikely(ret)) {
236 if (ret == AOP_TRUNCATED_PAGE) {
237 page_cache_release(page);
238 continue;
239 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240 goto unlock;
Zach Brown994fc28c2005-12-15 14:28:17 -0800241 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242 transfer_result = lo_do_transfer(lo, WRITE, page, offset,
243 bvec->bv_page, bv_offs, size, IV);
244 if (unlikely(transfer_result)) {
245 char *kaddr;
246
247 /*
248 * The transfer failed, but we still write the data to
249 * keep prepare/commit calls balanced.
250 */
251 printk(KERN_ERR "loop: transfer error block %llu\n",
252 (unsigned long long)index);
253 kaddr = kmap_atomic(page, KM_USER0);
254 memset(kaddr + offset, 0, size);
255 kunmap_atomic(kaddr, KM_USER0);
256 }
257 flush_dcache_page(page);
Zach Brown994fc28c2005-12-15 14:28:17 -0800258 ret = aops->commit_write(file, page, offset,
259 offset + size);
260 if (unlikely(ret)) {
261 if (ret == AOP_TRUNCATED_PAGE) {
262 page_cache_release(page);
263 continue;
264 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265 goto unlock;
Zach Brown994fc28c2005-12-15 14:28:17 -0800266 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700267 if (unlikely(transfer_result))
268 goto unlock;
269 bv_offs += size;
270 len -= size;
271 offset = 0;
272 index++;
273 pos += size;
274 unlock_page(page);
275 page_cache_release(page);
276 }
Zach Brown994fc28c2005-12-15 14:28:17 -0800277 ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278out:
Jes Sorensen1b1dcc12006-01-09 15:59:24 -0800279 mutex_unlock(&mapping->host->i_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 return ret;
281unlock:
282 unlock_page(page);
283 page_cache_release(page);
284fail:
285 ret = -1;
286 goto out;
287}
288
289/**
290 * __do_lo_send_write - helper for writing data to a loop device
291 *
292 * This helper just factors out common code between do_lo_send_direct_write()
293 * and do_lo_send_write().
294 */
Arjan van de Ven858119e2006-01-14 13:20:43 -0800295static int __do_lo_send_write(struct file *file,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296 u8 __user *buf, const int len, loff_t pos)
297{
298 ssize_t bw;
299 mm_segment_t old_fs = get_fs();
300
301 set_fs(get_ds());
302 bw = file->f_op->write(file, buf, len, &pos);
303 set_fs(old_fs);
304 if (likely(bw == len))
305 return 0;
306 printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
307 (unsigned long long)pos, len);
308 if (bw >= 0)
309 bw = -EIO;
310 return bw;
311}
312
313/**
314 * do_lo_send_direct_write - helper for writing data to a loop device
315 *
316 * This is the fast, non-transforming version for backing filesystems which do
317 * not implement the address space operations prepare_write and commit_write.
318 * It uses the write file operation which should be present on all writeable
319 * filesystems.
320 */
321static int do_lo_send_direct_write(struct loop_device *lo,
322 struct bio_vec *bvec, int bsize, loff_t pos, struct page *page)
323{
324 ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
325 (u8 __user *)kmap(bvec->bv_page) + bvec->bv_offset,
326 bvec->bv_len, pos);
327 kunmap(bvec->bv_page);
328 cond_resched();
329 return bw;
330}
331
332/**
333 * do_lo_send_write - helper for writing data to a loop device
334 *
335 * This is the slow, transforming version for filesystems which do not
336 * implement the address space operations prepare_write and commit_write. It
337 * uses the write file operation which should be present on all writeable
338 * filesystems.
339 *
340 * Using fops->write is slower than using aops->{prepare,commit}_write in the
341 * transforming case because we need to double buffer the data as we cannot do
342 * the transformations in place as we do not have direct access to the
343 * destination pages of the backing file.
344 */
345static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
346 int bsize, loff_t pos, struct page *page)
347{
348 int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
349 bvec->bv_offset, bvec->bv_len, pos >> 9);
350 if (likely(!ret))
351 return __do_lo_send_write(lo->lo_backing_file,
352 (u8 __user *)page_address(page), bvec->bv_len,
353 pos);
354 printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
355 "length %i.\n", (unsigned long long)pos, bvec->bv_len);
356 if (ret > 0)
357 ret = -EIO;
358 return ret;
359}
360
361static int lo_send(struct loop_device *lo, struct bio *bio, int bsize,
362 loff_t pos)
363{
364 int (*do_lo_send)(struct loop_device *, struct bio_vec *, int, loff_t,
365 struct page *page);
366 struct bio_vec *bvec;
367 struct page *page = NULL;
368 int i, ret = 0;
369
370 do_lo_send = do_lo_send_aops;
371 if (!(lo->lo_flags & LO_FLAGS_USE_AOPS)) {
372 do_lo_send = do_lo_send_direct_write;
373 if (lo->transfer != transfer_none) {
374 page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
375 if (unlikely(!page))
376 goto fail;
377 kmap(page);
378 do_lo_send = do_lo_send_write;
379 }
380 }
381 bio_for_each_segment(bvec, bio, i) {
382 ret = do_lo_send(lo, bvec, bsize, pos, page);
383 if (ret < 0)
384 break;
385 pos += bvec->bv_len;
386 }
387 if (page) {
388 kunmap(page);
389 __free_page(page);
390 }
391out:
392 return ret;
393fail:
394 printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
395 ret = -ENOMEM;
396 goto out;
397}
398
399struct lo_read_data {
400 struct loop_device *lo;
401 struct page *page;
402 unsigned offset;
403 int bsize;
404};
405
406static int
407lo_read_actor(read_descriptor_t *desc, struct page *page,
408 unsigned long offset, unsigned long size)
409{
410 unsigned long count = desc->count;
411 struct lo_read_data *p = desc->arg.data;
412 struct loop_device *lo = p->lo;
413 sector_t IV;
414
415 IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9))+(offset >> 9);
416
417 if (size > count)
418 size = count;
419
420 if (lo_do_transfer(lo, READ, page, offset, p->page, p->offset, size, IV)) {
421 size = 0;
422 printk(KERN_ERR "loop: transfer error block %ld\n",
423 page->index);
424 desc->error = -EINVAL;
425 }
426
427 flush_dcache_page(p->page);
428
429 desc->count = count - size;
430 desc->written += size;
431 p->offset += size;
432 return size;
433}
434
435static int
436do_lo_receive(struct loop_device *lo,
437 struct bio_vec *bvec, int bsize, loff_t pos)
438{
439 struct lo_read_data cookie;
440 struct file *file;
441 int retval;
442
443 cookie.lo = lo;
444 cookie.page = bvec->bv_page;
445 cookie.offset = bvec->bv_offset;
446 cookie.bsize = bsize;
447 file = lo->lo_backing_file;
448 retval = file->f_op->sendfile(file, &pos, bvec->bv_len,
449 lo_read_actor, &cookie);
450 return (retval < 0)? retval: 0;
451}
452
453static int
454lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
455{
456 struct bio_vec *bvec;
457 int i, ret = 0;
458
459 bio_for_each_segment(bvec, bio, i) {
460 ret = do_lo_receive(lo, bvec, bsize, pos);
461 if (ret < 0)
462 break;
463 pos += bvec->bv_len;
464 }
465 return ret;
466}
467
468static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
469{
470 loff_t pos;
471 int ret;
472
473 pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
474 if (bio_rw(bio) == WRITE)
475 ret = lo_send(lo, bio, lo->lo_blocksize, pos);
476 else
477 ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
478 return ret;
479}
480
481/*
482 * Add bio to back of pending list
483 */
484static void loop_add_bio(struct loop_device *lo, struct bio *bio)
485{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 if (lo->lo_biotail) {
487 lo->lo_biotail->bi_next = bio;
488 lo->lo_biotail = bio;
489 } else
490 lo->lo_bio = lo->lo_biotail = bio;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491}
492
493/*
494 * Grab first pending buffer
495 */
496static struct bio *loop_get_bio(struct loop_device *lo)
497{
498 struct bio *bio;
499
Linus Torvalds1da177e2005-04-16 15:20:36 -0700500 if ((bio = lo->lo_bio)) {
501 if (bio == lo->lo_biotail)
502 lo->lo_biotail = NULL;
503 lo->lo_bio = bio->bi_next;
504 bio->bi_next = NULL;
505 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700506
507 return bio;
508}
509
510static int loop_make_request(request_queue_t *q, struct bio *old_bio)
511{
512 struct loop_device *lo = q->queuedata;
513 int rw = bio_rw(old_bio);
514
Nick Piggin35a82d12005-06-23 00:09:06 -0700515 if (rw == READA)
516 rw = READ;
517
518 BUG_ON(!lo || (rw != READ && rw != WRITE));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
520 spin_lock_irq(&lo->lo_lock);
521 if (lo->lo_state != Lo_bound)
Nick Piggin35a82d12005-06-23 00:09:06 -0700522 goto out;
523 if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
524 goto out;
525 lo->lo_pending++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 loop_add_bio(lo, old_bio);
Nick Piggin35a82d12005-06-23 00:09:06 -0700527 spin_unlock_irq(&lo->lo_lock);
Ingo Molnar11b751a2006-01-09 15:59:27 -0800528 complete(&lo->lo_bh_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 return 0;
Nick Piggin35a82d12005-06-23 00:09:06 -0700530
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531out:
Nick Piggin35a82d12005-06-23 00:09:06 -0700532 if (lo->lo_pending == 0)
Ingo Molnar11b751a2006-01-09 15:59:27 -0800533 complete(&lo->lo_bh_done);
Nick Piggin35a82d12005-06-23 00:09:06 -0700534 spin_unlock_irq(&lo->lo_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 bio_io_error(old_bio, old_bio->bi_size);
536 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700537}
538
539/*
540 * kick off io on the underlying address space
541 */
542static void loop_unplug(request_queue_t *q)
543{
544 struct loop_device *lo = q->queuedata;
545
546 clear_bit(QUEUE_FLAG_PLUGGED, &q->queue_flags);
547 blk_run_address_space(lo->lo_backing_file->f_mapping);
548}
549
550struct switch_request {
551 struct file *file;
552 struct completion wait;
553};
554
555static void do_loop_switch(struct loop_device *, struct switch_request *);
556
557static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
558{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559 if (unlikely(!bio->bi_bdev)) {
560 do_loop_switch(lo, bio->bi_private);
561 bio_put(bio);
562 } else {
Nick Piggin35a82d12005-06-23 00:09:06 -0700563 int ret = do_bio_filebacked(lo, bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700564 bio_endio(bio, bio->bi_size, ret);
565 }
566}
567
568/*
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.
573 */
574static int loop_thread(void *data)
575{
576 struct loop_device *lo = data;
577 struct bio *bio;
578
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700579 daemonize("loop%d", lo->lo_number);
580
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 /*
582 * loop can be used in an encrypted device,
583 * hence, it mustn't be stopped at all
584 * because it could be indirectly used during suspension
585 */
586 current->flags |= PF_NOFREEZE;
587
588 set_user_nice(current, -20);
589
590 lo->lo_state = Lo_bound;
Nick Piggin35a82d12005-06-23 00:09:06 -0700591 lo->lo_pending = 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700592
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700593 /*
594 * complete it, we are running
595 */
596 complete(&lo->lo_done);
597
Linus Torvalds1da177e2005-04-16 15:20:36 -0700598 for (;;) {
Nick Piggin35a82d12005-06-23 00:09:06 -0700599 int pending;
600
Ingo Molnar11b751a2006-01-09 15:59:27 -0800601 if (wait_for_completion_interruptible(&lo->lo_bh_done))
Nick Piggin35a82d12005-06-23 00:09:06 -0700602 continue;
603
604 spin_lock_irq(&lo->lo_lock);
605
606 /*
Ingo Molnar11b751a2006-01-09 15:59:27 -0800607 * could be completed because of tear-down, not pending work
Nick Piggin35a82d12005-06-23 00:09:06 -0700608 */
609 if (unlikely(!lo->lo_pending)) {
610 spin_unlock_irq(&lo->lo_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 break;
Nick Piggin35a82d12005-06-23 00:09:06 -0700612 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613
614 bio = loop_get_bio(lo);
Nick Piggin35a82d12005-06-23 00:09:06 -0700615 lo->lo_pending--;
616 pending = lo->lo_pending;
617 spin_unlock_irq(&lo->lo_lock);
618
619 BUG_ON(!bio);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700620 loop_handle_bio(lo, bio);
621
622 /*
623 * upped both for pending work and tear-down, lo_pending
624 * will hit zero then
625 */
Nick Piggin35a82d12005-06-23 00:09:06 -0700626 if (unlikely(!pending))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700627 break;
628 }
629
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700630 complete(&lo->lo_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631 return 0;
632}
633
634/*
635 * loop_switch performs the hard work of switching a backing store.
636 * First it needs to flush existing IO, it does this by sending a magic
637 * BIO down the pipe. The completion of this BIO does the actual switch.
638 */
639static int loop_switch(struct loop_device *lo, struct file *file)
640{
641 struct switch_request w;
642 struct bio *bio = bio_alloc(GFP_KERNEL, 1);
643 if (!bio)
644 return -ENOMEM;
645 init_completion(&w.wait);
646 w.file = file;
647 bio->bi_private = &w;
648 bio->bi_bdev = NULL;
649 loop_make_request(lo->lo_queue, bio);
650 wait_for_completion(&w.wait);
651 return 0;
652}
653
654/*
655 * Do the actual switch; called from the BIO completion routine
656 */
657static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
658{
659 struct file *file = p->file;
660 struct file *old_file = lo->lo_backing_file;
661 struct address_space *mapping = file->f_mapping;
662
663 mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
664 lo->lo_backing_file = file;
665 lo->lo_blocksize = mapping->host->i_blksize;
666 lo->old_gfp_mask = mapping_gfp_mask(mapping);
667 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
668 complete(&p->wait);
669}
670
671
672/*
673 * loop_change_fd switched the backing store of a loopback device to
674 * a new file. This is useful for operating system installers to free up
675 * the original file and in High Availability environments to switch to
676 * an alternative location for the content in case of server meltdown.
677 * This can only work if the loop device is used read-only, and if the
678 * new backing store is the same size and type as the old backing store.
679 */
680static int loop_change_fd(struct loop_device *lo, struct file *lo_file,
681 struct block_device *bdev, unsigned int arg)
682{
683 struct file *file, *old_file;
684 struct inode *inode;
685 int error;
686
687 error = -ENXIO;
688 if (lo->lo_state != Lo_bound)
689 goto out;
690
691 /* the loop device has to be read-only */
692 error = -EINVAL;
693 if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
694 goto out;
695
696 error = -EBADF;
697 file = fget(arg);
698 if (!file)
699 goto out;
700
701 inode = file->f_mapping->host;
702 old_file = lo->lo_backing_file;
703
704 error = -EINVAL;
705
706 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
707 goto out_putf;
708
709 /* new backing store needs to support loop (eg sendfile) */
710 if (!inode->i_fop->sendfile)
711 goto out_putf;
712
713 /* size of the new backing store needs to be the same */
714 if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
715 goto out_putf;
716
717 /* and ... switch */
718 error = loop_switch(lo, file);
719 if (error)
720 goto out_putf;
721
722 fput(old_file);
723 return 0;
724
725 out_putf:
726 fput(file);
727 out:
728 return error;
729}
730
731static inline int is_loop_device(struct file *file)
732{
733 struct inode *i = file->f_mapping->host;
734
735 return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
736}
737
738static int loop_set_fd(struct loop_device *lo, struct file *lo_file,
739 struct block_device *bdev, unsigned int arg)
740{
741 struct file *file, *f;
742 struct inode *inode;
743 struct address_space *mapping;
744 unsigned lo_blocksize;
745 int lo_flags = 0;
746 int error;
747 loff_t size;
748
749 /* This is safe, since we have a reference from open(). */
750 __module_get(THIS_MODULE);
751
752 error = -EBADF;
753 file = fget(arg);
754 if (!file)
755 goto out;
756
757 error = -EBUSY;
758 if (lo->lo_state != Lo_unbound)
759 goto out_putf;
760
761 /* Avoid recursion */
762 f = file;
763 while (is_loop_device(f)) {
764 struct loop_device *l;
765
766 if (f->f_mapping->host->i_rdev == lo_file->f_mapping->host->i_rdev)
767 goto out_putf;
768
769 l = f->f_mapping->host->i_bdev->bd_disk->private_data;
770 if (l->lo_state == Lo_unbound) {
771 error = -EINVAL;
772 goto out_putf;
773 }
774 f = l->lo_backing_file;
775 }
776
777 mapping = file->f_mapping;
778 inode = mapping->host;
779
780 if (!(file->f_mode & FMODE_WRITE))
781 lo_flags |= LO_FLAGS_READ_ONLY;
782
783 error = -EINVAL;
784 if (S_ISREG(inode->i_mode) || S_ISBLK(inode->i_mode)) {
Christoph Hellwigf5e54d62006-06-28 04:26:44 -0700785 const struct address_space_operations *aops = mapping->a_ops;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786 /*
787 * If we can't read - sorry. If we only can't write - well,
788 * it's going to be read-only.
789 */
790 if (!file->f_op->sendfile)
791 goto out_putf;
792 if (aops->prepare_write && aops->commit_write)
793 lo_flags |= LO_FLAGS_USE_AOPS;
794 if (!(lo_flags & LO_FLAGS_USE_AOPS) && !file->f_op->write)
795 lo_flags |= LO_FLAGS_READ_ONLY;
796
797 lo_blocksize = inode->i_blksize;
798 error = 0;
799 } else {
800 goto out_putf;
801 }
802
803 size = get_loop_size(lo, file);
804
805 if ((loff_t)(sector_t)size != size) {
806 error = -EFBIG;
807 goto out_putf;
808 }
809
810 if (!(lo_file->f_mode & FMODE_WRITE))
811 lo_flags |= LO_FLAGS_READ_ONLY;
812
813 set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
814
815 lo->lo_blocksize = lo_blocksize;
816 lo->lo_device = bdev;
817 lo->lo_flags = lo_flags;
818 lo->lo_backing_file = file;
Constantine Sapuntzakiseefe85e2006-06-23 02:06:08 -0700819 lo->transfer = transfer_none;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820 lo->ioctl = NULL;
821 lo->lo_sizelimit = 0;
822 lo->old_gfp_mask = mapping_gfp_mask(mapping);
823 mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
824
825 lo->lo_bio = lo->lo_biotail = NULL;
826
827 /*
828 * set queue make_request_fn, and add limits based on lower level
829 * device
830 */
831 blk_queue_make_request(lo->lo_queue, loop_make_request);
832 lo->lo_queue->queuedata = lo;
833 lo->lo_queue->unplug_fn = loop_unplug;
834
835 set_capacity(disks[lo->lo_number], size);
836 bd_set_size(bdev, size << 9);
837
838 set_blocksize(bdev, lo_blocksize);
839
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700840 error = kernel_thread(loop_thread, lo, CLONE_KERNEL);
841 if (error < 0)
Herbert Poetzl3e88c172006-03-26 01:37:30 -0800842 goto out_putf;
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700843 wait_for_completion(&lo->lo_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 return 0;
845
846 out_putf:
847 fput(file);
848 out:
849 /* This is safe: open() is still holding a reference. */
850 module_put(THIS_MODULE);
851 return error;
852}
853
854static int
855loop_release_xfer(struct loop_device *lo)
856{
857 int err = 0;
858 struct loop_func_table *xfer = lo->lo_encryption;
859
860 if (xfer) {
861 if (xfer->release)
862 err = xfer->release(lo);
863 lo->transfer = NULL;
864 lo->lo_encryption = NULL;
865 module_put(xfer->owner);
866 }
867 return err;
868}
869
870static int
871loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
872 const struct loop_info64 *i)
873{
874 int err = 0;
875
876 if (xfer) {
877 struct module *owner = xfer->owner;
878
879 if (!try_module_get(owner))
880 return -EINVAL;
881 if (xfer->init)
882 err = xfer->init(lo, i);
883 if (err)
884 module_put(owner);
885 else
886 lo->lo_encryption = xfer;
887 }
888 return err;
889}
890
891static int loop_clr_fd(struct loop_device *lo, struct block_device *bdev)
892{
893 struct file *filp = lo->lo_backing_file;
Al Virob4e3ca12005-10-21 03:22:34 -0400894 gfp_t gfp = lo->old_gfp_mask;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700895
896 if (lo->lo_state != Lo_bound)
897 return -ENXIO;
898
899 if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
900 return -EBUSY;
901
902 if (filp == NULL)
903 return -EINVAL;
904
905 spin_lock_irq(&lo->lo_lock);
906 lo->lo_state = Lo_rundown;
Nick Piggin35a82d12005-06-23 00:09:06 -0700907 lo->lo_pending--;
908 if (!lo->lo_pending)
Ingo Molnar11b751a2006-01-09 15:59:27 -0800909 complete(&lo->lo_bh_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 spin_unlock_irq(&lo->lo_lock);
911
Linus Torvalds09c0dc62006-06-26 11:55:42 -0700912 wait_for_completion(&lo->lo_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913
914 lo->lo_backing_file = NULL;
915
916 loop_release_xfer(lo);
917 lo->transfer = NULL;
918 lo->ioctl = NULL;
919 lo->lo_device = NULL;
920 lo->lo_encryption = NULL;
921 lo->lo_offset = 0;
922 lo->lo_sizelimit = 0;
923 lo->lo_encrypt_key_size = 0;
924 lo->lo_flags = 0;
925 memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
926 memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
927 memset(lo->lo_file_name, 0, LO_NAME_SIZE);
928 invalidate_bdev(bdev, 0);
929 set_capacity(disks[lo->lo_number], 0);
930 bd_set_size(bdev, 0);
931 mapping_set_gfp_mask(filp->f_mapping, gfp);
932 lo->lo_state = Lo_unbound;
933 fput(filp);
934 /* This is safe: open() is still holding a reference. */
935 module_put(THIS_MODULE);
936 return 0;
937}
938
939static int
940loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
941{
942 int err;
943 struct loop_func_table *xfer;
944
945 if (lo->lo_encrypt_key_size && lo->lo_key_owner != current->uid &&
946 !capable(CAP_SYS_ADMIN))
947 return -EPERM;
948 if (lo->lo_state != Lo_bound)
949 return -ENXIO;
950 if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
951 return -EINVAL;
952
953 err = loop_release_xfer(lo);
954 if (err)
955 return err;
956
957 if (info->lo_encrypt_type) {
958 unsigned int type = info->lo_encrypt_type;
959
960 if (type >= MAX_LO_CRYPT)
961 return -EINVAL;
962 xfer = xfer_funcs[type];
963 if (xfer == NULL)
964 return -EINVAL;
965 } else
966 xfer = NULL;
967
968 err = loop_init_xfer(lo, xfer, info);
969 if (err)
970 return err;
971
972 if (lo->lo_offset != info->lo_offset ||
973 lo->lo_sizelimit != info->lo_sizelimit) {
974 lo->lo_offset = info->lo_offset;
975 lo->lo_sizelimit = info->lo_sizelimit;
976 if (figure_loop_size(lo))
977 return -EFBIG;
978 }
979
980 memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
981 memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
982 lo->lo_file_name[LO_NAME_SIZE-1] = 0;
983 lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
984
985 if (!xfer)
986 xfer = &none_funcs;
987 lo->transfer = xfer->transfer;
988 lo->ioctl = xfer->ioctl;
989
990 lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
991 lo->lo_init[0] = info->lo_init[0];
992 lo->lo_init[1] = info->lo_init[1];
993 if (info->lo_encrypt_key_size) {
994 memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
995 info->lo_encrypt_key_size);
996 lo->lo_key_owner = current->uid;
997 }
998
999 return 0;
1000}
1001
1002static int
1003loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1004{
1005 struct file *file = lo->lo_backing_file;
1006 struct kstat stat;
1007 int error;
1008
1009 if (lo->lo_state != Lo_bound)
1010 return -ENXIO;
1011 error = vfs_getattr(file->f_vfsmnt, file->f_dentry, &stat);
1012 if (error)
1013 return error;
1014 memset(info, 0, sizeof(*info));
1015 info->lo_number = lo->lo_number;
1016 info->lo_device = huge_encode_dev(stat.dev);
1017 info->lo_inode = stat.ino;
1018 info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1019 info->lo_offset = lo->lo_offset;
1020 info->lo_sizelimit = lo->lo_sizelimit;
1021 info->lo_flags = lo->lo_flags;
1022 memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1023 memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1024 info->lo_encrypt_type =
1025 lo->lo_encryption ? lo->lo_encryption->number : 0;
1026 if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1027 info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1028 memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1029 lo->lo_encrypt_key_size);
1030 }
1031 return 0;
1032}
1033
1034static void
1035loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1036{
1037 memset(info64, 0, sizeof(*info64));
1038 info64->lo_number = info->lo_number;
1039 info64->lo_device = info->lo_device;
1040 info64->lo_inode = info->lo_inode;
1041 info64->lo_rdevice = info->lo_rdevice;
1042 info64->lo_offset = info->lo_offset;
1043 info64->lo_sizelimit = 0;
1044 info64->lo_encrypt_type = info->lo_encrypt_type;
1045 info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1046 info64->lo_flags = info->lo_flags;
1047 info64->lo_init[0] = info->lo_init[0];
1048 info64->lo_init[1] = info->lo_init[1];
1049 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1050 memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1051 else
1052 memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1053 memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1054}
1055
1056static int
1057loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1058{
1059 memset(info, 0, sizeof(*info));
1060 info->lo_number = info64->lo_number;
1061 info->lo_device = info64->lo_device;
1062 info->lo_inode = info64->lo_inode;
1063 info->lo_rdevice = info64->lo_rdevice;
1064 info->lo_offset = info64->lo_offset;
1065 info->lo_encrypt_type = info64->lo_encrypt_type;
1066 info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1067 info->lo_flags = info64->lo_flags;
1068 info->lo_init[0] = info64->lo_init[0];
1069 info->lo_init[1] = info64->lo_init[1];
1070 if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1071 memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1072 else
1073 memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1074 memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1075
1076 /* error in case values were truncated */
1077 if (info->lo_device != info64->lo_device ||
1078 info->lo_rdevice != info64->lo_rdevice ||
1079 info->lo_inode != info64->lo_inode ||
1080 info->lo_offset != info64->lo_offset)
1081 return -EOVERFLOW;
1082
1083 return 0;
1084}
1085
1086static int
1087loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1088{
1089 struct loop_info info;
1090 struct loop_info64 info64;
1091
1092 if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1093 return -EFAULT;
1094 loop_info64_from_old(&info, &info64);
1095 return loop_set_status(lo, &info64);
1096}
1097
1098static int
1099loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1100{
1101 struct loop_info64 info64;
1102
1103 if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1104 return -EFAULT;
1105 return loop_set_status(lo, &info64);
1106}
1107
1108static int
1109loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1110 struct loop_info info;
1111 struct loop_info64 info64;
1112 int err = 0;
1113
1114 if (!arg)
1115 err = -EINVAL;
1116 if (!err)
1117 err = loop_get_status(lo, &info64);
1118 if (!err)
1119 err = loop_info64_to_old(&info64, &info);
1120 if (!err && copy_to_user(arg, &info, sizeof(info)))
1121 err = -EFAULT;
1122
1123 return err;
1124}
1125
1126static int
1127loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1128 struct loop_info64 info64;
1129 int err = 0;
1130
1131 if (!arg)
1132 err = -EINVAL;
1133 if (!err)
1134 err = loop_get_status(lo, &info64);
1135 if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1136 err = -EFAULT;
1137
1138 return err;
1139}
1140
1141static int lo_ioctl(struct inode * inode, struct file * file,
1142 unsigned int cmd, unsigned long arg)
1143{
1144 struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1145 int err;
1146
Ingo Molnarf85221d2006-03-23 03:00:38 -08001147 mutex_lock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001148 switch (cmd) {
1149 case LOOP_SET_FD:
1150 err = loop_set_fd(lo, file, inode->i_bdev, arg);
1151 break;
1152 case LOOP_CHANGE_FD:
1153 err = loop_change_fd(lo, file, inode->i_bdev, arg);
1154 break;
1155 case LOOP_CLR_FD:
1156 err = loop_clr_fd(lo, inode->i_bdev);
1157 break;
1158 case LOOP_SET_STATUS:
1159 err = loop_set_status_old(lo, (struct loop_info __user *) arg);
1160 break;
1161 case LOOP_GET_STATUS:
1162 err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1163 break;
1164 case LOOP_SET_STATUS64:
1165 err = loop_set_status64(lo, (struct loop_info64 __user *) arg);
1166 break;
1167 case LOOP_GET_STATUS64:
1168 err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1169 break;
1170 default:
1171 err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1172 }
Ingo Molnarf85221d2006-03-23 03:00:38 -08001173 mutex_unlock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001174 return err;
1175}
1176
1177static int lo_open(struct inode *inode, struct file *file)
1178{
1179 struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1180
Ingo Molnarf85221d2006-03-23 03:00:38 -08001181 mutex_lock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001182 lo->lo_refcnt++;
Ingo Molnarf85221d2006-03-23 03:00:38 -08001183 mutex_unlock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184
1185 return 0;
1186}
1187
1188static int lo_release(struct inode *inode, struct file *file)
1189{
1190 struct loop_device *lo = inode->i_bdev->bd_disk->private_data;
1191
Ingo Molnarf85221d2006-03-23 03:00:38 -08001192 mutex_lock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 --lo->lo_refcnt;
Ingo Molnarf85221d2006-03-23 03:00:38 -08001194 mutex_unlock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001195
1196 return 0;
1197}
1198
1199static struct block_device_operations lo_fops = {
1200 .owner = THIS_MODULE,
1201 .open = lo_open,
1202 .release = lo_release,
1203 .ioctl = lo_ioctl,
1204};
1205
1206/*
1207 * And now the modules code and kernel interface.
1208 */
1209module_param(max_loop, int, 0);
1210MODULE_PARM_DESC(max_loop, "Maximum number of loop devices (1-256)");
1211MODULE_LICENSE("GPL");
1212MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1213
1214int loop_register_transfer(struct loop_func_table *funcs)
1215{
1216 unsigned int n = funcs->number;
1217
1218 if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1219 return -EINVAL;
1220 xfer_funcs[n] = funcs;
1221 return 0;
1222}
1223
1224int loop_unregister_transfer(int number)
1225{
1226 unsigned int n = number;
1227 struct loop_device *lo;
1228 struct loop_func_table *xfer;
1229
1230 if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1231 return -EINVAL;
1232
1233 xfer_funcs[n] = NULL;
1234
1235 for (lo = &loop_dev[0]; lo < &loop_dev[max_loop]; lo++) {
Ingo Molnarf85221d2006-03-23 03:00:38 -08001236 mutex_lock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
1238 if (lo->lo_encryption == xfer)
1239 loop_release_xfer(lo);
1240
Ingo Molnarf85221d2006-03-23 03:00:38 -08001241 mutex_unlock(&lo->lo_ctl_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242 }
1243
1244 return 0;
1245}
1246
1247EXPORT_SYMBOL(loop_register_transfer);
1248EXPORT_SYMBOL(loop_unregister_transfer);
1249
1250static int __init loop_init(void)
1251{
1252 int i;
1253
1254 if (max_loop < 1 || max_loop > 256) {
1255 printk(KERN_WARNING "loop: invalid max_loop (must be between"
1256 " 1 and 256), using default (8)\n");
1257 max_loop = 8;
1258 }
1259
1260 if (register_blkdev(LOOP_MAJOR, "loop"))
1261 return -EIO;
1262
1263 loop_dev = kmalloc(max_loop * sizeof(struct loop_device), GFP_KERNEL);
1264 if (!loop_dev)
1265 goto out_mem1;
1266 memset(loop_dev, 0, max_loop * sizeof(struct loop_device));
1267
1268 disks = kmalloc(max_loop * sizeof(struct gendisk *), GFP_KERNEL);
1269 if (!disks)
1270 goto out_mem2;
1271
1272 for (i = 0; i < max_loop; i++) {
1273 disks[i] = alloc_disk(1);
1274 if (!disks[i])
1275 goto out_mem3;
1276 }
1277
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278 for (i = 0; i < max_loop; i++) {
1279 struct loop_device *lo = &loop_dev[i];
1280 struct gendisk *disk = disks[i];
1281
1282 memset(lo, 0, sizeof(*lo));
1283 lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1284 if (!lo->lo_queue)
1285 goto out_mem4;
Ingo Molnarf85221d2006-03-23 03:00:38 -08001286 mutex_init(&lo->lo_ctl_mutex);
Linus Torvalds09c0dc62006-06-26 11:55:42 -07001287 init_completion(&lo->lo_done);
Ingo Molnar11b751a2006-01-09 15:59:27 -08001288 init_completion(&lo->lo_bh_done);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289 lo->lo_number = i;
1290 spin_lock_init(&lo->lo_lock);
1291 disk->major = LOOP_MAJOR;
1292 disk->first_minor = i;
1293 disk->fops = &lo_fops;
1294 sprintf(disk->disk_name, "loop%d", i);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295 disk->private_data = lo;
1296 disk->queue = lo->lo_queue;
1297 }
1298
1299 /* We cannot fail after we call this, so another loop!*/
1300 for (i = 0; i < max_loop; i++)
1301 add_disk(disks[i]);
1302 printk(KERN_INFO "loop: loaded (max %d devices)\n", max_loop);
1303 return 0;
1304
1305out_mem4:
1306 while (i--)
Al Viro1312f402006-03-12 11:02:03 -05001307 blk_cleanup_queue(loop_dev[i].lo_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001308 i = max_loop;
1309out_mem3:
1310 while (i--)
1311 put_disk(disks[i]);
1312 kfree(disks);
1313out_mem2:
1314 kfree(loop_dev);
1315out_mem1:
1316 unregister_blkdev(LOOP_MAJOR, "loop");
1317 printk(KERN_ERR "loop: ran out of memory\n");
1318 return -ENOMEM;
1319}
1320
1321static void loop_exit(void)
1322{
1323 int i;
1324
1325 for (i = 0; i < max_loop; i++) {
1326 del_gendisk(disks[i]);
Al Viro1312f402006-03-12 11:02:03 -05001327 blk_cleanup_queue(loop_dev[i].lo_queue);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001328 put_disk(disks[i]);
1329 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001330 if (unregister_blkdev(LOOP_MAJOR, "loop"))
1331 printk(KERN_WARNING "loop: cannot unregister blkdev\n");
1332
1333 kfree(disks);
1334 kfree(loop_dev);
1335}
1336
1337module_init(loop_init);
1338module_exit(loop_exit);
1339
1340#ifndef MODULE
1341static int __init max_loop_setup(char *str)
1342{
1343 max_loop = simple_strtol(str, NULL, 0);
1344 return 1;
1345}
1346
1347__setup("max_loop=", max_loop_setup);
1348#endif