Root/drivers/block/loop.c

1/*
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 write_begin is not available on the backing filesystem.
44 * Anton Altaparmakov, 16 Feb 2005
45 *
46 * Still To Fix:
47 * - Advisory locking is ignored here.
48 * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
49 *
50 */
51
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/swap.h>
65#include <linux/slab.h>
66#include <linux/loop.h>
67#include <linux/compat.h>
68#include <linux/suspend.h>
69#include <linux/freezer.h>
70#include <linux/mutex.h>
71#include <linux/writeback.h>
72#include <linux/completion.h>
73#include <linux/highmem.h>
74#include <linux/kthread.h>
75#include <linux/splice.h>
76#include <linux/sysfs.h>
77#include <linux/miscdevice.h>
78#include <linux/falloc.h>
79
80#include <asm/uaccess.h>
81
82static DEFINE_IDR(loop_index_idr);
83static DEFINE_MUTEX(loop_index_mutex);
84
85static int max_part;
86static int part_shift;
87
88/*
89 * Transfer functions
90 */
91static int transfer_none(struct loop_device *lo, int cmd,
92             struct page *raw_page, unsigned raw_off,
93             struct page *loop_page, unsigned loop_off,
94             int size, sector_t real_block)
95{
96    char *raw_buf = kmap_atomic(raw_page) + raw_off;
97    char *loop_buf = kmap_atomic(loop_page) + loop_off;
98
99    if (cmd == READ)
100        memcpy(loop_buf, raw_buf, size);
101    else
102        memcpy(raw_buf, loop_buf, size);
103
104    kunmap_atomic(loop_buf);
105    kunmap_atomic(raw_buf);
106    cond_resched();
107    return 0;
108}
109
110static int transfer_xor(struct loop_device *lo, int cmd,
111            struct page *raw_page, unsigned raw_off,
112            struct page *loop_page, unsigned loop_off,
113            int size, sector_t real_block)
114{
115    char *raw_buf = kmap_atomic(raw_page) + raw_off;
116    char *loop_buf = kmap_atomic(loop_page) + loop_off;
117    char *in, *out, *key;
118    int i, keysize;
119
120    if (cmd == READ) {
121        in = raw_buf;
122        out = loop_buf;
123    } else {
124        in = loop_buf;
125        out = raw_buf;
126    }
127
128    key = lo->lo_encrypt_key;
129    keysize = lo->lo_encrypt_key_size;
130    for (i = 0; i < size; i++)
131        *out++ = *in++ ^ key[(i & 511) % keysize];
132
133    kunmap_atomic(loop_buf);
134    kunmap_atomic(raw_buf);
135    cond_resched();
136    return 0;
137}
138
139static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
140{
141    if (unlikely(info->lo_encrypt_key_size <= 0))
142        return -EINVAL;
143    return 0;
144}
145
146static struct loop_func_table none_funcs = {
147    .number = LO_CRYPT_NONE,
148    .transfer = transfer_none,
149};
150
151static struct loop_func_table xor_funcs = {
152    .number = LO_CRYPT_XOR,
153    .transfer = transfer_xor,
154    .init = xor_init
155};
156
157/* xfer_funcs[0] is special - its release function is never called */
158static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
159    &none_funcs,
160    &xor_funcs
161};
162
163static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
164{
165    loff_t size, loopsize;
166
167    /* Compute loopsize in bytes */
168    size = i_size_read(file->f_mapping->host);
169    loopsize = size - offset;
170    /* offset is beyond i_size, wierd but possible */
171    if (loopsize < 0)
172        return 0;
173
174    if (sizelimit > 0 && sizelimit < loopsize)
175        loopsize = sizelimit;
176    /*
177     * Unfortunately, if we want to do I/O on the device,
178     * the number of 512-byte sectors has to fit into a sector_t.
179     */
180    return loopsize >> 9;
181}
182
183static loff_t get_loop_size(struct loop_device *lo, struct file *file)
184{
185    return get_size(lo->lo_offset, lo->lo_sizelimit, file);
186}
187
188static int
189figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
190{
191    loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
192    sector_t x = (sector_t)size;
193
194    if (unlikely((loff_t)x != size))
195        return -EFBIG;
196    if (lo->lo_offset != offset)
197        lo->lo_offset = offset;
198    if (lo->lo_sizelimit != sizelimit)
199        lo->lo_sizelimit = sizelimit;
200    set_capacity(lo->lo_disk, x);
201    return 0;
202}
203
204static inline int
205lo_do_transfer(struct loop_device *lo, int cmd,
206           struct page *rpage, unsigned roffs,
207           struct page *lpage, unsigned loffs,
208           int size, sector_t rblock)
209{
210    if (unlikely(!lo->transfer))
211        return 0;
212
213    return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
214}
215
216/**
217 * __do_lo_send_write - helper for writing data to a loop device
218 *
219 * This helper just factors out common code between do_lo_send_direct_write()
220 * and do_lo_send_write().
221 */
222static int __do_lo_send_write(struct file *file,
223        u8 *buf, const int len, loff_t pos)
224{
225    ssize_t bw;
226    mm_segment_t old_fs = get_fs();
227
228    set_fs(get_ds());
229    bw = file->f_op->write(file, buf, len, &pos);
230    set_fs(old_fs);
231    if (likely(bw == len))
232        return 0;
233    printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
234            (unsigned long long)pos, len);
235    if (bw >= 0)
236        bw = -EIO;
237    return bw;
238}
239
240/**
241 * do_lo_send_direct_write - helper for writing data to a loop device
242 *
243 * This is the fast, non-transforming version that does not need double
244 * buffering.
245 */
246static int do_lo_send_direct_write(struct loop_device *lo,
247        struct bio_vec *bvec, loff_t pos, struct page *page)
248{
249    ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
250            kmap(bvec->bv_page) + bvec->bv_offset,
251            bvec->bv_len, pos);
252    kunmap(bvec->bv_page);
253    cond_resched();
254    return bw;
255}
256
257/**
258 * do_lo_send_write - helper for writing data to a loop device
259 *
260 * This is the slow, transforming version that needs to double buffer the
261 * data as it cannot do the transformations in place without having direct
262 * access to the destination pages of the backing file.
263 */
264static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
265        loff_t pos, struct page *page)
266{
267    int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
268            bvec->bv_offset, bvec->bv_len, pos >> 9);
269    if (likely(!ret))
270        return __do_lo_send_write(lo->lo_backing_file,
271                page_address(page), bvec->bv_len,
272                pos);
273    printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
274            "length %i.\n", (unsigned long long)pos, bvec->bv_len);
275    if (ret > 0)
276        ret = -EIO;
277    return ret;
278}
279
280static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
281{
282    int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
283            struct page *page);
284    struct bio_vec *bvec;
285    struct page *page = NULL;
286    int i, ret = 0;
287
288    if (lo->transfer != transfer_none) {
289        page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
290        if (unlikely(!page))
291            goto fail;
292        kmap(page);
293        do_lo_send = do_lo_send_write;
294    } else {
295        do_lo_send = do_lo_send_direct_write;
296    }
297
298    bio_for_each_segment(bvec, bio, i) {
299        ret = do_lo_send(lo, bvec, pos, page);
300        if (ret < 0)
301            break;
302        pos += bvec->bv_len;
303    }
304    if (page) {
305        kunmap(page);
306        __free_page(page);
307    }
308out:
309    return ret;
310fail:
311    printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
312    ret = -ENOMEM;
313    goto out;
314}
315
316struct lo_read_data {
317    struct loop_device *lo;
318    struct page *page;
319    unsigned offset;
320    int bsize;
321};
322
323static int
324lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
325        struct splice_desc *sd)
326{
327    struct lo_read_data *p = sd->u.data;
328    struct loop_device *lo = p->lo;
329    struct page *page = buf->page;
330    sector_t IV;
331    int size;
332
333    IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
334                            (buf->offset >> 9);
335    size = sd->len;
336    if (size > p->bsize)
337        size = p->bsize;
338
339    if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
340        printk(KERN_ERR "loop: transfer error block %ld\n",
341               page->index);
342        size = -EINVAL;
343    }
344
345    flush_dcache_page(p->page);
346
347    if (size > 0)
348        p->offset += size;
349
350    return size;
351}
352
353static int
354lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
355{
356    return __splice_from_pipe(pipe, sd, lo_splice_actor);
357}
358
359static ssize_t
360do_lo_receive(struct loop_device *lo,
361          struct bio_vec *bvec, int bsize, loff_t pos)
362{
363    struct lo_read_data cookie;
364    struct splice_desc sd;
365    struct file *file;
366    ssize_t retval;
367
368    cookie.lo = lo;
369    cookie.page = bvec->bv_page;
370    cookie.offset = bvec->bv_offset;
371    cookie.bsize = bsize;
372
373    sd.len = 0;
374    sd.total_len = bvec->bv_len;
375    sd.flags = 0;
376    sd.pos = pos;
377    sd.u.data = &cookie;
378
379    file = lo->lo_backing_file;
380    retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
381
382    return retval;
383}
384
385static int
386lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
387{
388    struct bio_vec *bvec;
389    ssize_t s;
390    int i;
391
392    bio_for_each_segment(bvec, bio, i) {
393        s = do_lo_receive(lo, bvec, bsize, pos);
394        if (s < 0)
395            return s;
396
397        if (s != bvec->bv_len) {
398            zero_fill_bio(bio);
399            break;
400        }
401        pos += bvec->bv_len;
402    }
403    return 0;
404}
405
406static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
407{
408    loff_t pos;
409    int ret;
410
411    pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
412
413    if (bio_rw(bio) == WRITE) {
414        struct file *file = lo->lo_backing_file;
415
416        if (bio->bi_rw & REQ_FLUSH) {
417            ret = vfs_fsync(file, 0);
418            if (unlikely(ret && ret != -EINVAL)) {
419                ret = -EIO;
420                goto out;
421            }
422        }
423
424        /*
425         * We use punch hole to reclaim the free space used by the
426         * image a.k.a. discard. However we do not support discard if
427         * encryption is enabled, because it may give an attacker
428         * useful information.
429         */
430        if (bio->bi_rw & REQ_DISCARD) {
431            struct file *file = lo->lo_backing_file;
432            int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
433
434            if ((!file->f_op->fallocate) ||
435                lo->lo_encrypt_key_size) {
436                ret = -EOPNOTSUPP;
437                goto out;
438            }
439            ret = file->f_op->fallocate(file, mode, pos,
440                            bio->bi_size);
441            if (unlikely(ret && ret != -EINVAL &&
442                     ret != -EOPNOTSUPP))
443                ret = -EIO;
444            goto out;
445        }
446
447        ret = lo_send(lo, bio, pos);
448
449        if ((bio->bi_rw & REQ_FUA) && !ret) {
450            ret = vfs_fsync(file, 0);
451            if (unlikely(ret && ret != -EINVAL))
452                ret = -EIO;
453        }
454    } else
455        ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
456
457out:
458    return ret;
459}
460
461/*
462 * Add bio to back of pending list
463 */
464static void loop_add_bio(struct loop_device *lo, struct bio *bio)
465{
466    bio_list_add(&lo->lo_bio_list, bio);
467}
468
469/*
470 * Grab first pending buffer
471 */
472static struct bio *loop_get_bio(struct loop_device *lo)
473{
474    return bio_list_pop(&lo->lo_bio_list);
475}
476
477static void loop_make_request(struct request_queue *q, struct bio *old_bio)
478{
479    struct loop_device *lo = q->queuedata;
480    int rw = bio_rw(old_bio);
481
482    if (rw == READA)
483        rw = READ;
484
485    BUG_ON(!lo || (rw != READ && rw != WRITE));
486
487    spin_lock_irq(&lo->lo_lock);
488    if (lo->lo_state != Lo_bound)
489        goto out;
490    if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
491        goto out;
492    loop_add_bio(lo, old_bio);
493    wake_up(&lo->lo_event);
494    spin_unlock_irq(&lo->lo_lock);
495    return;
496
497out:
498    spin_unlock_irq(&lo->lo_lock);
499    bio_io_error(old_bio);
500}
501
502struct switch_request {
503    struct file *file;
504    struct completion wait;
505};
506
507static void do_loop_switch(struct loop_device *, struct switch_request *);
508
509static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
510{
511    if (unlikely(!bio->bi_bdev)) {
512        do_loop_switch(lo, bio->bi_private);
513        bio_put(bio);
514    } else {
515        int ret = do_bio_filebacked(lo, bio);
516        bio_endio(bio, ret);
517    }
518}
519
520/*
521 * worker thread that handles reads/writes to file backed loop devices,
522 * to avoid blocking in our make_request_fn. it also does loop decrypting
523 * on reads for block backed loop, as that is too heavy to do from
524 * b_end_io context where irqs may be disabled.
525 *
526 * Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
527 * calling kthread_stop(). Therefore once kthread_should_stop() is
528 * true, make_request will not place any more requests. Therefore
529 * once kthread_should_stop() is true and lo_bio is NULL, we are
530 * done with the loop.
531 */
532static int loop_thread(void *data)
533{
534    struct loop_device *lo = data;
535    struct bio *bio;
536
537    set_user_nice(current, -20);
538
539    while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
540
541        wait_event_interruptible(lo->lo_event,
542                !bio_list_empty(&lo->lo_bio_list) ||
543                kthread_should_stop());
544
545        if (bio_list_empty(&lo->lo_bio_list))
546            continue;
547        spin_lock_irq(&lo->lo_lock);
548        bio = loop_get_bio(lo);
549        spin_unlock_irq(&lo->lo_lock);
550
551        BUG_ON(!bio);
552        loop_handle_bio(lo, bio);
553    }
554
555    return 0;
556}
557
558/*
559 * loop_switch performs the hard work of switching a backing store.
560 * First it needs to flush existing IO, it does this by sending a magic
561 * BIO down the pipe. The completion of this BIO does the actual switch.
562 */
563static int loop_switch(struct loop_device *lo, struct file *file)
564{
565    struct switch_request w;
566    struct bio *bio = bio_alloc(GFP_KERNEL, 0);
567    if (!bio)
568        return -ENOMEM;
569    init_completion(&w.wait);
570    w.file = file;
571    bio->bi_private = &w;
572    bio->bi_bdev = NULL;
573    loop_make_request(lo->lo_queue, bio);
574    wait_for_completion(&w.wait);
575    return 0;
576}
577
578/*
579 * Helper to flush the IOs in loop, but keeping loop thread running
580 */
581static int loop_flush(struct loop_device *lo)
582{
583    /* loop not yet configured, no running thread, nothing to flush */
584    if (!lo->lo_thread)
585        return 0;
586
587    return loop_switch(lo, NULL);
588}
589
590/*
591 * Do the actual switch; called from the BIO completion routine
592 */
593static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
594{
595    struct file *file = p->file;
596    struct file *old_file = lo->lo_backing_file;
597    struct address_space *mapping;
598
599    /* if no new file, only flush of queued bios requested */
600    if (!file)
601        goto out;
602
603    mapping = file->f_mapping;
604    mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
605    lo->lo_backing_file = file;
606    lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
607        mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
608    lo->old_gfp_mask = mapping_gfp_mask(mapping);
609    mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
610out:
611    complete(&p->wait);
612}
613
614
615/*
616 * loop_change_fd switched the backing store of a loopback device to
617 * a new file. This is useful for operating system installers to free up
618 * the original file and in High Availability environments to switch to
619 * an alternative location for the content in case of server meltdown.
620 * This can only work if the loop device is used read-only, and if the
621 * new backing store is the same size and type as the old backing store.
622 */
623static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
624              unsigned int arg)
625{
626    struct file *file, *old_file;
627    struct inode *inode;
628    int error;
629
630    error = -ENXIO;
631    if (lo->lo_state != Lo_bound)
632        goto out;
633
634    /* the loop device has to be read-only */
635    error = -EINVAL;
636    if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
637        goto out;
638
639    error = -EBADF;
640    file = fget(arg);
641    if (!file)
642        goto out;
643
644    inode = file->f_mapping->host;
645    old_file = lo->lo_backing_file;
646
647    error = -EINVAL;
648
649    if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
650        goto out_putf;
651
652    /* size of the new backing store needs to be the same */
653    if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
654        goto out_putf;
655
656    /* and ... switch */
657    error = loop_switch(lo, file);
658    if (error)
659        goto out_putf;
660
661    fput(old_file);
662    if (lo->lo_flags & LO_FLAGS_PARTSCAN)
663        ioctl_by_bdev(bdev, BLKRRPART, 0);
664    return 0;
665
666 out_putf:
667    fput(file);
668 out:
669    return error;
670}
671
672static inline int is_loop_device(struct file *file)
673{
674    struct inode *i = file->f_mapping->host;
675
676    return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
677}
678
679/* loop sysfs attributes */
680
681static ssize_t loop_attr_show(struct device *dev, char *page,
682                  ssize_t (*callback)(struct loop_device *, char *))
683{
684    struct gendisk *disk = dev_to_disk(dev);
685    struct loop_device *lo = disk->private_data;
686
687    return callback(lo, page);
688}
689
690#define LOOP_ATTR_RO(_name) \
691static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
692static ssize_t loop_attr_do_show_##_name(struct device *d, \
693                struct device_attribute *attr, char *b) \
694{ \
695    return loop_attr_show(d, b, loop_attr_##_name##_show); \
696} \
697static struct device_attribute loop_attr_##_name = \
698    __ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
699
700static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
701{
702    ssize_t ret;
703    char *p = NULL;
704
705    spin_lock_irq(&lo->lo_lock);
706    if (lo->lo_backing_file)
707        p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
708    spin_unlock_irq(&lo->lo_lock);
709
710    if (IS_ERR_OR_NULL(p))
711        ret = PTR_ERR(p);
712    else {
713        ret = strlen(p);
714        memmove(buf, p, ret);
715        buf[ret++] = '\n';
716        buf[ret] = 0;
717    }
718
719    return ret;
720}
721
722static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
723{
724    return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
725}
726
727static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
728{
729    return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
730}
731
732static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
733{
734    int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
735
736    return sprintf(buf, "%s\n", autoclear ? "1" : "0");
737}
738
739static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
740{
741    int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
742
743    return sprintf(buf, "%s\n", partscan ? "1" : "0");
744}
745
746LOOP_ATTR_RO(backing_file);
747LOOP_ATTR_RO(offset);
748LOOP_ATTR_RO(sizelimit);
749LOOP_ATTR_RO(autoclear);
750LOOP_ATTR_RO(partscan);
751
752static struct attribute *loop_attrs[] = {
753    &loop_attr_backing_file.attr,
754    &loop_attr_offset.attr,
755    &loop_attr_sizelimit.attr,
756    &loop_attr_autoclear.attr,
757    &loop_attr_partscan.attr,
758    NULL,
759};
760
761static struct attribute_group loop_attribute_group = {
762    .name = "loop",
763    .attrs= loop_attrs,
764};
765
766static int loop_sysfs_init(struct loop_device *lo)
767{
768    return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
769                  &loop_attribute_group);
770}
771
772static void loop_sysfs_exit(struct loop_device *lo)
773{
774    sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
775               &loop_attribute_group);
776}
777
778static void loop_config_discard(struct loop_device *lo)
779{
780    struct file *file = lo->lo_backing_file;
781    struct inode *inode = file->f_mapping->host;
782    struct request_queue *q = lo->lo_queue;
783
784    /*
785     * We use punch hole to reclaim the free space used by the
786     * image a.k.a. discard. However we do support discard if
787     * encryption is enabled, because it may give an attacker
788     * useful information.
789     */
790    if ((!file->f_op->fallocate) ||
791        lo->lo_encrypt_key_size) {
792        q->limits.discard_granularity = 0;
793        q->limits.discard_alignment = 0;
794        q->limits.max_discard_sectors = 0;
795        q->limits.discard_zeroes_data = 0;
796        queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
797        return;
798    }
799
800    q->limits.discard_granularity = inode->i_sb->s_blocksize;
801    q->limits.discard_alignment = 0;
802    q->limits.max_discard_sectors = UINT_MAX >> 9;
803    q->limits.discard_zeroes_data = 1;
804    queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
805}
806
807static int loop_set_fd(struct loop_device *lo, fmode_t mode,
808               struct block_device *bdev, unsigned int arg)
809{
810    struct file *file, *f;
811    struct inode *inode;
812    struct address_space *mapping;
813    unsigned lo_blocksize;
814    int lo_flags = 0;
815    int error;
816    loff_t size;
817
818    /* This is safe, since we have a reference from open(). */
819    __module_get(THIS_MODULE);
820
821    error = -EBADF;
822    file = fget(arg);
823    if (!file)
824        goto out;
825
826    error = -EBUSY;
827    if (lo->lo_state != Lo_unbound)
828        goto out_putf;
829
830    /* Avoid recursion */
831    f = file;
832    while (is_loop_device(f)) {
833        struct loop_device *l;
834
835        if (f->f_mapping->host->i_bdev == bdev)
836            goto out_putf;
837
838        l = f->f_mapping->host->i_bdev->bd_disk->private_data;
839        if (l->lo_state == Lo_unbound) {
840            error = -EINVAL;
841            goto out_putf;
842        }
843        f = l->lo_backing_file;
844    }
845
846    mapping = file->f_mapping;
847    inode = mapping->host;
848
849    error = -EINVAL;
850    if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
851        goto out_putf;
852
853    if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
854        !file->f_op->write)
855        lo_flags |= LO_FLAGS_READ_ONLY;
856
857    lo_blocksize = S_ISBLK(inode->i_mode) ?
858        inode->i_bdev->bd_block_size : PAGE_SIZE;
859
860    error = -EFBIG;
861    size = get_loop_size(lo, file);
862    if ((loff_t)(sector_t)size != size)
863        goto out_putf;
864
865    error = 0;
866
867    set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
868
869    lo->lo_blocksize = lo_blocksize;
870    lo->lo_device = bdev;
871    lo->lo_flags = lo_flags;
872    lo->lo_backing_file = file;
873    lo->transfer = transfer_none;
874    lo->ioctl = NULL;
875    lo->lo_sizelimit = 0;
876    lo->old_gfp_mask = mapping_gfp_mask(mapping);
877    mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
878
879    bio_list_init(&lo->lo_bio_list);
880
881    /*
882     * set queue make_request_fn, and add limits based on lower level
883     * device
884     */
885    blk_queue_make_request(lo->lo_queue, loop_make_request);
886    lo->lo_queue->queuedata = lo;
887
888    if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
889        blk_queue_flush(lo->lo_queue, REQ_FLUSH);
890
891    set_capacity(lo->lo_disk, size);
892    bd_set_size(bdev, size << 9);
893    loop_sysfs_init(lo);
894    /* let user-space know about the new size */
895    kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
896
897    set_blocksize(bdev, lo_blocksize);
898
899    lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
900                        lo->lo_number);
901    if (IS_ERR(lo->lo_thread)) {
902        error = PTR_ERR(lo->lo_thread);
903        goto out_clr;
904    }
905    lo->lo_state = Lo_bound;
906    wake_up_process(lo->lo_thread);
907    if (part_shift)
908        lo->lo_flags |= LO_FLAGS_PARTSCAN;
909    if (lo->lo_flags & LO_FLAGS_PARTSCAN)
910        ioctl_by_bdev(bdev, BLKRRPART, 0);
911    return 0;
912
913out_clr:
914    loop_sysfs_exit(lo);
915    lo->lo_thread = NULL;
916    lo->lo_device = NULL;
917    lo->lo_backing_file = NULL;
918    lo->lo_flags = 0;
919    set_capacity(lo->lo_disk, 0);
920    invalidate_bdev(bdev);
921    bd_set_size(bdev, 0);
922    kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
923    mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
924    lo->lo_state = Lo_unbound;
925 out_putf:
926    fput(file);
927 out:
928    /* This is safe: open() is still holding a reference. */
929    module_put(THIS_MODULE);
930    return error;
931}
932
933static int
934loop_release_xfer(struct loop_device *lo)
935{
936    int err = 0;
937    struct loop_func_table *xfer = lo->lo_encryption;
938
939    if (xfer) {
940        if (xfer->release)
941            err = xfer->release(lo);
942        lo->transfer = NULL;
943        lo->lo_encryption = NULL;
944        module_put(xfer->owner);
945    }
946    return err;
947}
948
949static int
950loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
951           const struct loop_info64 *i)
952{
953    int err = 0;
954
955    if (xfer) {
956        struct module *owner = xfer->owner;
957
958        if (!try_module_get(owner))
959            return -EINVAL;
960        if (xfer->init)
961            err = xfer->init(lo, i);
962        if (err)
963            module_put(owner);
964        else
965            lo->lo_encryption = xfer;
966    }
967    return err;
968}
969
970static int loop_clr_fd(struct loop_device *lo)
971{
972    struct file *filp = lo->lo_backing_file;
973    gfp_t gfp = lo->old_gfp_mask;
974    struct block_device *bdev = lo->lo_device;
975
976    if (lo->lo_state != Lo_bound)
977        return -ENXIO;
978
979    if (lo->lo_refcnt > 1) /* we needed one fd for the ioctl */
980        return -EBUSY;
981
982    if (filp == NULL)
983        return -EINVAL;
984
985    spin_lock_irq(&lo->lo_lock);
986    lo->lo_state = Lo_rundown;
987    spin_unlock_irq(&lo->lo_lock);
988
989    kthread_stop(lo->lo_thread);
990
991    spin_lock_irq(&lo->lo_lock);
992    lo->lo_backing_file = NULL;
993    spin_unlock_irq(&lo->lo_lock);
994
995    loop_release_xfer(lo);
996    lo->transfer = NULL;
997    lo->ioctl = NULL;
998    lo->lo_device = NULL;
999    lo->lo_encryption = NULL;
1000    lo->lo_offset = 0;
1001    lo->lo_sizelimit = 0;
1002    lo->lo_encrypt_key_size = 0;
1003    lo->lo_thread = NULL;
1004    memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
1005    memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
1006    memset(lo->lo_file_name, 0, LO_NAME_SIZE);
1007    if (bdev)
1008        invalidate_bdev(bdev);
1009    set_capacity(lo->lo_disk, 0);
1010    loop_sysfs_exit(lo);
1011    if (bdev) {
1012        bd_set_size(bdev, 0);
1013        /* let user-space know about this change */
1014        kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1015    }
1016    mapping_set_gfp_mask(filp->f_mapping, gfp);
1017    lo->lo_state = Lo_unbound;
1018    /* This is safe: open() is still holding a reference. */
1019    module_put(THIS_MODULE);
1020    if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
1021        ioctl_by_bdev(bdev, BLKRRPART, 0);
1022    lo->lo_flags = 0;
1023    if (!part_shift)
1024        lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
1025    mutex_unlock(&lo->lo_ctl_mutex);
1026    /*
1027     * Need not hold lo_ctl_mutex to fput backing file.
1028     * Calling fput holding lo_ctl_mutex triggers a circular
1029     * lock dependency possibility warning as fput can take
1030     * bd_mutex which is usually taken before lo_ctl_mutex.
1031     */
1032    fput(filp);
1033    return 0;
1034}
1035
1036static int
1037loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
1038{
1039    int err;
1040    struct loop_func_table *xfer;
1041    uid_t uid = current_uid();
1042
1043    if (lo->lo_encrypt_key_size &&
1044        lo->lo_key_owner != uid &&
1045        !capable(CAP_SYS_ADMIN))
1046        return -EPERM;
1047    if (lo->lo_state != Lo_bound)
1048        return -ENXIO;
1049    if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
1050        return -EINVAL;
1051
1052    err = loop_release_xfer(lo);
1053    if (err)
1054        return err;
1055
1056    if (info->lo_encrypt_type) {
1057        unsigned int type = info->lo_encrypt_type;
1058
1059        if (type >= MAX_LO_CRYPT)
1060            return -EINVAL;
1061        xfer = xfer_funcs[type];
1062        if (xfer == NULL)
1063            return -EINVAL;
1064    } else
1065        xfer = NULL;
1066
1067    err = loop_init_xfer(lo, xfer, info);
1068    if (err)
1069        return err;
1070
1071    if (lo->lo_offset != info->lo_offset ||
1072        lo->lo_sizelimit != info->lo_sizelimit) {
1073        if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
1074            return -EFBIG;
1075    }
1076    loop_config_discard(lo);
1077
1078    memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
1079    memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
1080    lo->lo_file_name[LO_NAME_SIZE-1] = 0;
1081    lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
1082
1083    if (!xfer)
1084        xfer = &none_funcs;
1085    lo->transfer = xfer->transfer;
1086    lo->ioctl = xfer->ioctl;
1087
1088    if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
1089         (info->lo_flags & LO_FLAGS_AUTOCLEAR))
1090        lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
1091
1092    if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
1093         !(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
1094        lo->lo_flags |= LO_FLAGS_PARTSCAN;
1095        lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
1096        ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
1097    }
1098
1099    lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
1100    lo->lo_init[0] = info->lo_init[0];
1101    lo->lo_init[1] = info->lo_init[1];
1102    if (info->lo_encrypt_key_size) {
1103        memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
1104               info->lo_encrypt_key_size);
1105        lo->lo_key_owner = uid;
1106    }
1107
1108    return 0;
1109}
1110
1111static int
1112loop_get_status(struct loop_device *lo, struct loop_info64 *info)
1113{
1114    struct file *file = lo->lo_backing_file;
1115    struct kstat stat;
1116    int error;
1117
1118    if (lo->lo_state != Lo_bound)
1119        return -ENXIO;
1120    error = vfs_getattr(file->f_path.mnt, file->f_path.dentry, &stat);
1121    if (error)
1122        return error;
1123    memset(info, 0, sizeof(*info));
1124    info->lo_number = lo->lo_number;
1125    info->lo_device = huge_encode_dev(stat.dev);
1126    info->lo_inode = stat.ino;
1127    info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
1128    info->lo_offset = lo->lo_offset;
1129    info->lo_sizelimit = lo->lo_sizelimit;
1130    info->lo_flags = lo->lo_flags;
1131    memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
1132    memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
1133    info->lo_encrypt_type =
1134        lo->lo_encryption ? lo->lo_encryption->number : 0;
1135    if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
1136        info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
1137        memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
1138               lo->lo_encrypt_key_size);
1139    }
1140    return 0;
1141}
1142
1143static void
1144loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
1145{
1146    memset(info64, 0, sizeof(*info64));
1147    info64->lo_number = info->lo_number;
1148    info64->lo_device = info->lo_device;
1149    info64->lo_inode = info->lo_inode;
1150    info64->lo_rdevice = info->lo_rdevice;
1151    info64->lo_offset = info->lo_offset;
1152    info64->lo_sizelimit = 0;
1153    info64->lo_encrypt_type = info->lo_encrypt_type;
1154    info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
1155    info64->lo_flags = info->lo_flags;
1156    info64->lo_init[0] = info->lo_init[0];
1157    info64->lo_init[1] = info->lo_init[1];
1158    if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1159        memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
1160    else
1161        memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
1162    memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
1163}
1164
1165static int
1166loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
1167{
1168    memset(info, 0, sizeof(*info));
1169    info->lo_number = info64->lo_number;
1170    info->lo_device = info64->lo_device;
1171    info->lo_inode = info64->lo_inode;
1172    info->lo_rdevice = info64->lo_rdevice;
1173    info->lo_offset = info64->lo_offset;
1174    info->lo_encrypt_type = info64->lo_encrypt_type;
1175    info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
1176    info->lo_flags = info64->lo_flags;
1177    info->lo_init[0] = info64->lo_init[0];
1178    info->lo_init[1] = info64->lo_init[1];
1179    if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1180        memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1181    else
1182        memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
1183    memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1184
1185    /* error in case values were truncated */
1186    if (info->lo_device != info64->lo_device ||
1187        info->lo_rdevice != info64->lo_rdevice ||
1188        info->lo_inode != info64->lo_inode ||
1189        info->lo_offset != info64->lo_offset)
1190        return -EOVERFLOW;
1191
1192    return 0;
1193}
1194
1195static int
1196loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
1197{
1198    struct loop_info info;
1199    struct loop_info64 info64;
1200
1201    if (copy_from_user(&info, arg, sizeof (struct loop_info)))
1202        return -EFAULT;
1203    loop_info64_from_old(&info, &info64);
1204    return loop_set_status(lo, &info64);
1205}
1206
1207static int
1208loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
1209{
1210    struct loop_info64 info64;
1211
1212    if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
1213        return -EFAULT;
1214    return loop_set_status(lo, &info64);
1215}
1216
1217static int
1218loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
1219    struct loop_info info;
1220    struct loop_info64 info64;
1221    int err = 0;
1222
1223    if (!arg)
1224        err = -EINVAL;
1225    if (!err)
1226        err = loop_get_status(lo, &info64);
1227    if (!err)
1228        err = loop_info64_to_old(&info64, &info);
1229    if (!err && copy_to_user(arg, &info, sizeof(info)))
1230        err = -EFAULT;
1231
1232    return err;
1233}
1234
1235static int
1236loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
1237    struct loop_info64 info64;
1238    int err = 0;
1239
1240    if (!arg)
1241        err = -EINVAL;
1242    if (!err)
1243        err = loop_get_status(lo, &info64);
1244    if (!err && copy_to_user(arg, &info64, sizeof(info64)))
1245        err = -EFAULT;
1246
1247    return err;
1248}
1249
1250static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
1251{
1252    int err;
1253    sector_t sec;
1254    loff_t sz;
1255
1256    err = -ENXIO;
1257    if (unlikely(lo->lo_state != Lo_bound))
1258        goto out;
1259    err = figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
1260    if (unlikely(err))
1261        goto out;
1262    sec = get_capacity(lo->lo_disk);
1263    /* the width of sector_t may be narrow for bit-shift */
1264    sz = sec;
1265    sz <<= 9;
1266    mutex_lock(&bdev->bd_mutex);
1267    bd_set_size(bdev, sz);
1268    /* let user-space know about the new size */
1269    kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
1270    mutex_unlock(&bdev->bd_mutex);
1271
1272 out:
1273    return err;
1274}
1275
1276static int lo_ioctl(struct block_device *bdev, fmode_t mode,
1277    unsigned int cmd, unsigned long arg)
1278{
1279    struct loop_device *lo = bdev->bd_disk->private_data;
1280    int err;
1281
1282    mutex_lock_nested(&lo->lo_ctl_mutex, 1);
1283    switch (cmd) {
1284    case LOOP_SET_FD:
1285        err = loop_set_fd(lo, mode, bdev, arg);
1286        break;
1287    case LOOP_CHANGE_FD:
1288        err = loop_change_fd(lo, bdev, arg);
1289        break;
1290    case LOOP_CLR_FD:
1291        /* loop_clr_fd would have unlocked lo_ctl_mutex on success */
1292        err = loop_clr_fd(lo);
1293        if (!err)
1294            goto out_unlocked;
1295        break;
1296    case LOOP_SET_STATUS:
1297        err = -EPERM;
1298        if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1299            err = loop_set_status_old(lo,
1300                    (struct loop_info __user *)arg);
1301        break;
1302    case LOOP_GET_STATUS:
1303        err = loop_get_status_old(lo, (struct loop_info __user *) arg);
1304        break;
1305    case LOOP_SET_STATUS64:
1306        err = -EPERM;
1307        if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1308            err = loop_set_status64(lo,
1309                    (struct loop_info64 __user *) arg);
1310        break;
1311    case LOOP_GET_STATUS64:
1312        err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
1313        break;
1314    case LOOP_SET_CAPACITY:
1315        err = -EPERM;
1316        if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
1317            err = loop_set_capacity(lo, bdev);
1318        break;
1319    default:
1320        err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
1321    }
1322    mutex_unlock(&lo->lo_ctl_mutex);
1323
1324out_unlocked:
1325    return err;
1326}
1327
1328#ifdef CONFIG_COMPAT
1329struct compat_loop_info {
1330    compat_int_t lo_number; /* ioctl r/o */
1331    compat_dev_t lo_device; /* ioctl r/o */
1332    compat_ulong_t lo_inode; /* ioctl r/o */
1333    compat_dev_t lo_rdevice; /* ioctl r/o */
1334    compat_int_t lo_offset;
1335    compat_int_t lo_encrypt_type;
1336    compat_int_t lo_encrypt_key_size; /* ioctl w/o */
1337    compat_int_t lo_flags; /* ioctl r/o */
1338    char lo_name[LO_NAME_SIZE];
1339    unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
1340    compat_ulong_t lo_init[2];
1341    char reserved[4];
1342};
1343
1344/*
1345 * Transfer 32-bit compatibility structure in userspace to 64-bit loop info
1346 * - noinlined to reduce stack space usage in main part of driver
1347 */
1348static noinline int
1349loop_info64_from_compat(const struct compat_loop_info __user *arg,
1350            struct loop_info64 *info64)
1351{
1352    struct compat_loop_info info;
1353
1354    if (copy_from_user(&info, arg, sizeof(info)))
1355        return -EFAULT;
1356
1357    memset(info64, 0, sizeof(*info64));
1358    info64->lo_number = info.lo_number;
1359    info64->lo_device = info.lo_device;
1360    info64->lo_inode = info.lo_inode;
1361    info64->lo_rdevice = info.lo_rdevice;
1362    info64->lo_offset = info.lo_offset;
1363    info64->lo_sizelimit = 0;
1364    info64->lo_encrypt_type = info.lo_encrypt_type;
1365    info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
1366    info64->lo_flags = info.lo_flags;
1367    info64->lo_init[0] = info.lo_init[0];
1368    info64->lo_init[1] = info.lo_init[1];
1369    if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1370        memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
1371    else
1372        memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
1373    memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
1374    return 0;
1375}
1376
1377/*
1378 * Transfer 64-bit loop info to 32-bit compatibility structure in userspace
1379 * - noinlined to reduce stack space usage in main part of driver
1380 */
1381static noinline int
1382loop_info64_to_compat(const struct loop_info64 *info64,
1383              struct compat_loop_info __user *arg)
1384{
1385    struct compat_loop_info info;
1386
1387    memset(&info, 0, sizeof(info));
1388    info.lo_number = info64->lo_number;
1389    info.lo_device = info64->lo_device;
1390    info.lo_inode = info64->lo_inode;
1391    info.lo_rdevice = info64->lo_rdevice;
1392    info.lo_offset = info64->lo_offset;
1393    info.lo_encrypt_type = info64->lo_encrypt_type;
1394    info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
1395    info.lo_flags = info64->lo_flags;
1396    info.lo_init[0] = info64->lo_init[0];
1397    info.lo_init[1] = info64->lo_init[1];
1398    if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
1399        memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
1400    else
1401        memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
1402    memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
1403
1404    /* error in case values were truncated */
1405    if (info.lo_device != info64->lo_device ||
1406        info.lo_rdevice != info64->lo_rdevice ||
1407        info.lo_inode != info64->lo_inode ||
1408        info.lo_offset != info64->lo_offset ||
1409        info.lo_init[0] != info64->lo_init[0] ||
1410        info.lo_init[1] != info64->lo_init[1])
1411        return -EOVERFLOW;
1412
1413    if (copy_to_user(arg, &info, sizeof(info)))
1414        return -EFAULT;
1415    return 0;
1416}
1417
1418static int
1419loop_set_status_compat(struct loop_device *lo,
1420               const struct compat_loop_info __user *arg)
1421{
1422    struct loop_info64 info64;
1423    int ret;
1424
1425    ret = loop_info64_from_compat(arg, &info64);
1426    if (ret < 0)
1427        return ret;
1428    return loop_set_status(lo, &info64);
1429}
1430
1431static int
1432loop_get_status_compat(struct loop_device *lo,
1433               struct compat_loop_info __user *arg)
1434{
1435    struct loop_info64 info64;
1436    int err = 0;
1437
1438    if (!arg)
1439        err = -EINVAL;
1440    if (!err)
1441        err = loop_get_status(lo, &info64);
1442    if (!err)
1443        err = loop_info64_to_compat(&info64, arg);
1444    return err;
1445}
1446
1447static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
1448               unsigned int cmd, unsigned long arg)
1449{
1450    struct loop_device *lo = bdev->bd_disk->private_data;
1451    int err;
1452
1453    switch(cmd) {
1454    case LOOP_SET_STATUS:
1455        mutex_lock(&lo->lo_ctl_mutex);
1456        err = loop_set_status_compat(
1457            lo, (const struct compat_loop_info __user *) arg);
1458        mutex_unlock(&lo->lo_ctl_mutex);
1459        break;
1460    case LOOP_GET_STATUS:
1461        mutex_lock(&lo->lo_ctl_mutex);
1462        err = loop_get_status_compat(
1463            lo, (struct compat_loop_info __user *) arg);
1464        mutex_unlock(&lo->lo_ctl_mutex);
1465        break;
1466    case LOOP_SET_CAPACITY:
1467    case LOOP_CLR_FD:
1468    case LOOP_GET_STATUS64:
1469    case LOOP_SET_STATUS64:
1470        arg = (unsigned long) compat_ptr(arg);
1471    case LOOP_SET_FD:
1472    case LOOP_CHANGE_FD:
1473        err = lo_ioctl(bdev, mode, cmd, arg);
1474        break;
1475    default:
1476        err = -ENOIOCTLCMD;
1477        break;
1478    }
1479    return err;
1480}
1481#endif
1482
1483static int lo_open(struct block_device *bdev, fmode_t mode)
1484{
1485    struct loop_device *lo;
1486    int err = 0;
1487
1488    mutex_lock(&loop_index_mutex);
1489    lo = bdev->bd_disk->private_data;
1490    if (!lo) {
1491        err = -ENXIO;
1492        goto out;
1493    }
1494
1495    mutex_lock(&lo->lo_ctl_mutex);
1496    lo->lo_refcnt++;
1497    mutex_unlock(&lo->lo_ctl_mutex);
1498out:
1499    mutex_unlock(&loop_index_mutex);
1500    return err;
1501}
1502
1503static int lo_release(struct gendisk *disk, fmode_t mode)
1504{
1505    struct loop_device *lo = disk->private_data;
1506    int err;
1507
1508    mutex_lock(&lo->lo_ctl_mutex);
1509
1510    if (--lo->lo_refcnt)
1511        goto out;
1512
1513    if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
1514        /*
1515         * In autoclear mode, stop the loop thread
1516         * and remove configuration after last close.
1517         */
1518        err = loop_clr_fd(lo);
1519        if (!err)
1520            goto out_unlocked;
1521    } else {
1522        /*
1523         * Otherwise keep thread (if running) and config,
1524         * but flush possible ongoing bios in thread.
1525         */
1526        loop_flush(lo);
1527    }
1528
1529out:
1530    mutex_unlock(&lo->lo_ctl_mutex);
1531out_unlocked:
1532    return 0;
1533}
1534
1535static const struct block_device_operations lo_fops = {
1536    .owner = THIS_MODULE,
1537    .open = lo_open,
1538    .release = lo_release,
1539    .ioctl = lo_ioctl,
1540#ifdef CONFIG_COMPAT
1541    .compat_ioctl = lo_compat_ioctl,
1542#endif
1543};
1544
1545/*
1546 * And now the modules code and kernel interface.
1547 */
1548static int max_loop;
1549module_param(max_loop, int, S_IRUGO);
1550MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
1551module_param(max_part, int, S_IRUGO);
1552MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
1553MODULE_LICENSE("GPL");
1554MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
1555
1556int loop_register_transfer(struct loop_func_table *funcs)
1557{
1558    unsigned int n = funcs->number;
1559
1560    if (n >= MAX_LO_CRYPT || xfer_funcs[n])
1561        return -EINVAL;
1562    xfer_funcs[n] = funcs;
1563    return 0;
1564}
1565
1566static int unregister_transfer_cb(int id, void *ptr, void *data)
1567{
1568    struct loop_device *lo = ptr;
1569    struct loop_func_table *xfer = data;
1570
1571    mutex_lock(&lo->lo_ctl_mutex);
1572    if (lo->lo_encryption == xfer)
1573        loop_release_xfer(lo);
1574    mutex_unlock(&lo->lo_ctl_mutex);
1575    return 0;
1576}
1577
1578int loop_unregister_transfer(int number)
1579{
1580    unsigned int n = number;
1581    struct loop_func_table *xfer;
1582
1583    if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
1584        return -EINVAL;
1585
1586    xfer_funcs[n] = NULL;
1587    idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
1588    return 0;
1589}
1590
1591EXPORT_SYMBOL(loop_register_transfer);
1592EXPORT_SYMBOL(loop_unregister_transfer);
1593
1594static int loop_add(struct loop_device **l, int i)
1595{
1596    struct loop_device *lo;
1597    struct gendisk *disk;
1598    int err;
1599
1600    err = -ENOMEM;
1601    lo = kzalloc(sizeof(*lo), GFP_KERNEL);
1602    if (!lo)
1603        goto out;
1604
1605    if (!idr_pre_get(&loop_index_idr, GFP_KERNEL))
1606        goto out_free_dev;
1607
1608    if (i >= 0) {
1609        int m;
1610
1611        /* create specific i in the index */
1612        err = idr_get_new_above(&loop_index_idr, lo, i, &m);
1613        if (err >= 0 && i != m) {
1614            idr_remove(&loop_index_idr, m);
1615            err = -EEXIST;
1616        }
1617    } else if (i == -1) {
1618        int m;
1619
1620        /* get next free nr */
1621        err = idr_get_new(&loop_index_idr, lo, &m);
1622        if (err >= 0)
1623            i = m;
1624    } else {
1625        err = -EINVAL;
1626    }
1627    if (err < 0)
1628        goto out_free_dev;
1629
1630    lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
1631    if (!lo->lo_queue)
1632        goto out_free_dev;
1633
1634    disk = lo->lo_disk = alloc_disk(1 << part_shift);
1635    if (!disk)
1636        goto out_free_queue;
1637
1638    /*
1639     * Disable partition scanning by default. The in-kernel partition
1640     * scanning can be requested individually per-device during its
1641     * setup. Userspace can always add and remove partitions from all
1642     * devices. The needed partition minors are allocated from the
1643     * extended minor space, the main loop device numbers will continue
1644     * to match the loop minors, regardless of the number of partitions
1645     * used.
1646     *
1647     * If max_part is given, partition scanning is globally enabled for
1648     * all loop devices. The minors for the main loop devices will be
1649     * multiples of max_part.
1650     *
1651     * Note: Global-for-all-devices, set-only-at-init, read-only module
1652     * parameteters like 'max_loop' and 'max_part' make things needlessly
1653     * complicated, are too static, inflexible and may surprise
1654     * userspace tools. Parameters like this in general should be avoided.
1655     */
1656    if (!part_shift)
1657        disk->flags |= GENHD_FL_NO_PART_SCAN;
1658    disk->flags |= GENHD_FL_EXT_DEVT;
1659    mutex_init(&lo->lo_ctl_mutex);
1660    lo->lo_number = i;
1661    lo->lo_thread = NULL;
1662    init_waitqueue_head(&lo->lo_event);
1663    spin_lock_init(&lo->lo_lock);
1664    disk->major = LOOP_MAJOR;
1665    disk->first_minor = i << part_shift;
1666    disk->fops = &lo_fops;
1667    disk->private_data = lo;
1668    disk->queue = lo->lo_queue;
1669    sprintf(disk->disk_name, "loop%d", i);
1670    add_disk(disk);
1671    *l = lo;
1672    return lo->lo_number;
1673
1674out_free_queue:
1675    blk_cleanup_queue(lo->lo_queue);
1676out_free_dev:
1677    kfree(lo);
1678out:
1679    return err;
1680}
1681
1682static void loop_remove(struct loop_device *lo)
1683{
1684    del_gendisk(lo->lo_disk);
1685    blk_cleanup_queue(lo->lo_queue);
1686    put_disk(lo->lo_disk);
1687    kfree(lo);
1688}
1689
1690static int find_free_cb(int id, void *ptr, void *data)
1691{
1692    struct loop_device *lo = ptr;
1693    struct loop_device **l = data;
1694
1695    if (lo->lo_state == Lo_unbound) {
1696        *l = lo;
1697        return 1;
1698    }
1699    return 0;
1700}
1701
1702static int loop_lookup(struct loop_device **l, int i)
1703{
1704    struct loop_device *lo;
1705    int ret = -ENODEV;
1706
1707    if (i < 0) {
1708        int err;
1709
1710        err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
1711        if (err == 1) {
1712            *l = lo;
1713            ret = lo->lo_number;
1714        }
1715        goto out;
1716    }
1717
1718    /* lookup and return a specific i */
1719    lo = idr_find(&loop_index_idr, i);
1720    if (lo) {
1721        *l = lo;
1722        ret = lo->lo_number;
1723    }
1724out:
1725    return ret;
1726}
1727
1728static struct kobject *loop_probe(dev_t dev, int *part, void *data)
1729{
1730    struct loop_device *lo;
1731    struct kobject *kobj;
1732    int err;
1733
1734    mutex_lock(&loop_index_mutex);
1735    err = loop_lookup(&lo, MINOR(dev) >> part_shift);
1736    if (err < 0)
1737        err = loop_add(&lo, MINOR(dev) >> part_shift);
1738    if (err < 0)
1739        kobj = ERR_PTR(err);
1740    else
1741        kobj = get_disk(lo->lo_disk);
1742    mutex_unlock(&loop_index_mutex);
1743
1744    *part = 0;
1745    return kobj;
1746}
1747
1748static long loop_control_ioctl(struct file *file, unsigned int cmd,
1749                   unsigned long parm)
1750{
1751    struct loop_device *lo;
1752    int ret = -ENOSYS;
1753
1754    mutex_lock(&loop_index_mutex);
1755    switch (cmd) {
1756    case LOOP_CTL_ADD:
1757        ret = loop_lookup(&lo, parm);
1758        if (ret >= 0) {
1759            ret = -EEXIST;
1760            break;
1761        }
1762        ret = loop_add(&lo, parm);
1763        break;
1764    case LOOP_CTL_REMOVE:
1765        ret = loop_lookup(&lo, parm);
1766        if (ret < 0)
1767            break;
1768        mutex_lock(&lo->lo_ctl_mutex);
1769        if (lo->lo_state != Lo_unbound) {
1770            ret = -EBUSY;
1771            mutex_unlock(&lo->lo_ctl_mutex);
1772            break;
1773        }
1774        if (lo->lo_refcnt > 0) {
1775            ret = -EBUSY;
1776            mutex_unlock(&lo->lo_ctl_mutex);
1777            break;
1778        }
1779        lo->lo_disk->private_data = NULL;
1780        mutex_unlock(&lo->lo_ctl_mutex);
1781        idr_remove(&loop_index_idr, lo->lo_number);
1782        loop_remove(lo);
1783        break;
1784    case LOOP_CTL_GET_FREE:
1785        ret = loop_lookup(&lo, -1);
1786        if (ret >= 0)
1787            break;
1788        ret = loop_add(&lo, -1);
1789    }
1790    mutex_unlock(&loop_index_mutex);
1791
1792    return ret;
1793}
1794
1795static const struct file_operations loop_ctl_fops = {
1796    .open = nonseekable_open,
1797    .unlocked_ioctl = loop_control_ioctl,
1798    .compat_ioctl = loop_control_ioctl,
1799    .owner = THIS_MODULE,
1800    .llseek = noop_llseek,
1801};
1802
1803static struct miscdevice loop_misc = {
1804    .minor = LOOP_CTRL_MINOR,
1805    .name = "loop-control",
1806    .fops = &loop_ctl_fops,
1807};
1808
1809MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
1810MODULE_ALIAS("devname:loop-control");
1811
1812static int __init loop_init(void)
1813{
1814    int i, nr;
1815    unsigned long range;
1816    struct loop_device *lo;
1817    int err;
1818
1819    err = misc_register(&loop_misc);
1820    if (err < 0)
1821        return err;
1822
1823    part_shift = 0;
1824    if (max_part > 0) {
1825        part_shift = fls(max_part);
1826
1827        /*
1828         * Adjust max_part according to part_shift as it is exported
1829         * to user space so that user can decide correct minor number
1830         * if [s]he want to create more devices.
1831         *
1832         * Note that -1 is required because partition 0 is reserved
1833         * for the whole disk.
1834         */
1835        max_part = (1UL << part_shift) - 1;
1836    }
1837
1838    if ((1UL << part_shift) > DISK_MAX_PARTS)
1839        return -EINVAL;
1840
1841    if (max_loop > 1UL << (MINORBITS - part_shift))
1842        return -EINVAL;
1843
1844    /*
1845     * If max_loop is specified, create that many devices upfront.
1846     * This also becomes a hard limit. If max_loop is not specified,
1847     * create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
1848     * init time. Loop devices can be requested on-demand with the
1849     * /dev/loop-control interface, or be instantiated by accessing
1850     * a 'dead' device node.
1851     */
1852    if (max_loop) {
1853        nr = max_loop;
1854        range = max_loop << part_shift;
1855    } else {
1856        nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
1857        range = 1UL << MINORBITS;
1858    }
1859
1860    if (register_blkdev(LOOP_MAJOR, "loop"))
1861        return -EIO;
1862
1863    blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
1864                  THIS_MODULE, loop_probe, NULL, NULL);
1865
1866    /* pre-create number of devices given by config or max_loop */
1867    mutex_lock(&loop_index_mutex);
1868    for (i = 0; i < nr; i++)
1869        loop_add(&lo, i);
1870    mutex_unlock(&loop_index_mutex);
1871
1872    printk(KERN_INFO "loop: module loaded\n");
1873    return 0;
1874}
1875
1876static int loop_exit_cb(int id, void *ptr, void *data)
1877{
1878    struct loop_device *lo = ptr;
1879
1880    loop_remove(lo);
1881    return 0;
1882}
1883
1884static void __exit loop_exit(void)
1885{
1886    unsigned long range;
1887
1888    range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
1889
1890    idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
1891    idr_remove_all(&loop_index_idr);
1892    idr_destroy(&loop_index_idr);
1893
1894    blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
1895    unregister_blkdev(LOOP_MAJOR, "loop");
1896
1897    misc_deregister(&loop_misc);
1898}
1899
1900module_init(loop_init);
1901module_exit(loop_exit);
1902
1903#ifndef MODULE
1904static int __init max_loop_setup(char *str)
1905{
1906    max_loop = simple_strtol(str, NULL, 0);
1907    return 1;
1908}
1909
1910__setup("max_loop=", max_loop_setup);
1911#endif
1912

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