/*
* linux/drivers/block/loop.c
*
* Written by Theodore Ts'o, 3/29/93
*
* Copyright 1993 by Theodore Ts'o. Redistribution of this file is
* permitted under the GNU General Public License.
*
* DES encryption plus some minor changes by Werner Almesberger, 30-MAY-1993
* more DES encryption plus IDEA encryption by Nicholas J. Leon, June 20, 1996
*
* Modularized and updated for 1.1.16 kernel - Mitch Dsouza 28th May 1994
* Adapted for 1.3.59 kernel - Andries Brouwer, 1 Feb 1996
*
* Fixed do_loop_request() re-entrancy - Vincent.Renardias@waw.com Mar 20, 1997
*
* Added devfs support - Richard Gooch <rgooch@atnf.csiro.au> 16-Jan-1998
*
* Handle sparse backing files correctly - Kenn Humborg, Jun 28, 1998
*
* Loadable modules and other fixes by AK, 1998
*
* Make real block number available to downstream transfer functions, enables
* CBC (and relatives) mode encryption requiring unique IVs per data block.
* Reed H. Petty, rhp@draper.net
*
* Maximum number of loop devices now dynamic via max_loop module parameter.
* Russell Kroll <rkroll@exploits.org> 19990701
*
* Maximum number of loop devices when compiled-in now selectable by passing
* max_loop=<1-255> to the kernel on boot.
* Erik I. Bolsø, <eriki@himolde.no>, Oct 31, 1999
*
* Completely rewrite request handling to be make_request_fn style and
* non blocking, pushing work to a helper thread. Lots of fixes from
* Al Viro too.
* Jens Axboe <axboe@suse.de>, Nov 2000
*
* Support up to 256 loop devices
* Heinz Mauelshagen <mge@sistina.com>, Feb 2002
*
* Support for falling back on the write file operation when the address space
* operations write_begin is not available on the backing filesystem.
* Anton Altaparmakov, 16 Feb 2005
*
* Still To Fix:
* - Advisory locking is ignored here.
* - Should use an own CAP_* category instead of CAP_SYS_ADMIN
*
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/major.h>
#include <linux/wait.h>
#include <linux/blkdev.h>
#include <linux/blkpg.h>
#include <linux/init.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <linux/loop.h>
#include <linux/compat.h>
#include <linux/suspend.h>
#include <linux/freezer.h>
#include <linux/mutex.h>
#include <linux/writeback.h>
#include <linux/completion.h>
#include <linux/highmem.h>
#include <linux/kthread.h>
#include <linux/splice.h>
#include <linux/sysfs.h>
#include <linux/miscdevice.h>
#include <linux/falloc.h>
#include <asm/uaccess.h>
static DEFINE_IDR(loop_index_idr);
static DEFINE_MUTEX(loop_index_mutex);
static int max_part;
static int part_shift;
/*
* Transfer functions
*/
static int transfer_none(struct loop_device *lo, int cmd,
struct page *raw_page, unsigned raw_off,
struct page *loop_page, unsigned loop_off,
int size, sector_t real_block)
{
char *raw_buf = kmap_atomic(raw_page) + raw_off;
char *loop_buf = kmap_atomic(loop_page) + loop_off;
if (cmd == READ)
memcpy(loop_buf, raw_buf, size);
else
memcpy(raw_buf, loop_buf, size);
kunmap_atomic(loop_buf);
kunmap_atomic(raw_buf);
cond_resched();
return 0;
}
static int transfer_xor(struct loop_device *lo, int cmd,
struct page *raw_page, unsigned raw_off,
struct page *loop_page, unsigned loop_off,
int size, sector_t real_block)
{
char *raw_buf = kmap_atomic(raw_page) + raw_off;
char *loop_buf = kmap_atomic(loop_page) + loop_off;
char *in, *out, *key;
int i, keysize;
if (cmd == READ) {
in = raw_buf;
out = loop_buf;
} else {
in = loop_buf;
out = raw_buf;
}
key = lo->lo_encrypt_key;
keysize = lo->lo_encrypt_key_size;
for (i = 0; i < size; i++)
*out++ = *in++ ^ key[(i & 511) % keysize];
kunmap_atomic(loop_buf);
kunmap_atomic(raw_buf);
cond_resched();
return 0;
}
static int xor_init(struct loop_device *lo, const struct loop_info64 *info)
{
if (unlikely(info->lo_encrypt_key_size <= 0))
return -EINVAL;
return 0;
}
static struct loop_func_table none_funcs = {
.number = LO_CRYPT_NONE,
.transfer = transfer_none,
};
static struct loop_func_table xor_funcs = {
.number = LO_CRYPT_XOR,
.transfer = transfer_xor,
.init = xor_init
};
/* xfer_funcs[0] is special - its release function is never called */
static struct loop_func_table *xfer_funcs[MAX_LO_CRYPT] = {
&none_funcs,
&xor_funcs
};
static loff_t get_size(loff_t offset, loff_t sizelimit, struct file *file)
{
loff_t loopsize;
/* Compute loopsize in bytes */
loopsize = i_size_read(file->f_mapping->host);
if (offset > 0)
loopsize -= offset;
/* offset is beyond i_size, weird but possible */
if (loopsize < 0)
return 0;
if (sizelimit > 0 && sizelimit < loopsize)
loopsize = sizelimit;
/*
* Unfortunately, if we want to do I/O on the device,
* the number of 512-byte sectors has to fit into a sector_t.
*/
return loopsize >> 9;
}
static loff_t get_loop_size(struct loop_device *lo, struct file *file)
{
return get_size(lo->lo_offset, lo->lo_sizelimit, file);
}
static int
figure_loop_size(struct loop_device *lo, loff_t offset, loff_t sizelimit)
{
loff_t size = get_size(offset, sizelimit, lo->lo_backing_file);
sector_t x = (sector_t)size;
struct block_device *bdev = lo->lo_device;
if (unlikely((loff_t)x != size))
return -EFBIG;
if (lo->lo_offset != offset)
lo->lo_offset = offset;
if (lo->lo_sizelimit != sizelimit)
lo->lo_sizelimit = sizelimit;
set_capacity(lo->lo_disk, x);
bd_set_size(bdev, (loff_t)get_capacity(bdev->bd_disk) << 9);
/* let user-space know about the new size */
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
return 0;
}
static inline int
lo_do_transfer(struct loop_device *lo, int cmd,
struct page *rpage, unsigned roffs,
struct page *lpage, unsigned loffs,
int size, sector_t rblock)
{
if (unlikely(!lo->transfer))
return 0;
return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
}
/**
* __do_lo_send_write - helper for writing data to a loop device
*
* This helper just factors out common code between do_lo_send_direct_write()
* and do_lo_send_write().
*/
static int __do_lo_send_write(struct file *file,
u8 *buf, const int len, loff_t pos)
{
ssize_t bw;
mm_segment_t old_fs = get_fs();
file_start_write(file);
set_fs(get_ds());
bw = file->f_op->write(file, buf, len, &pos);
set_fs(old_fs);
file_end_write(file);
if (likely(bw == len))
return 0;
printk(KERN_ERR "loop: Write error at byte offset %llu, length %i.\n",
(unsigned long long)pos, len);
if (bw >= 0)
bw = -EIO;
return bw;
}
/**
* do_lo_send_direct_write - helper for writing data to a loop device
*
* This is the fast, non-transforming version that does not need double
* buffering.
*/
static int do_lo_send_direct_write(struct loop_device *lo,
struct bio_vec *bvec, loff_t pos, struct page *page)
{
ssize_t bw = __do_lo_send_write(lo->lo_backing_file,
kmap(bvec->bv_page) + bvec->bv_offset,
bvec->bv_len, pos);
kunmap(bvec->bv_page);
cond_resched();
return bw;
}
/**
* do_lo_send_write - helper for writing data to a loop device
*
* This is the slow, transforming version that needs to double buffer the
* data as it cannot do the transformations in place without having direct
* access to the destination pages of the backing file.
*/
static int do_lo_send_write(struct loop_device *lo, struct bio_vec *bvec,
loff_t pos, struct page *page)
{
int ret = lo_do_transfer(lo, WRITE, page, 0, bvec->bv_page,
bvec->bv_offset, bvec->bv_len, pos >> 9);
if (likely(!ret))
return __do_lo_send_write(lo->lo_backing_file,
page_address(page), bvec->bv_len,
pos);
printk(KERN_ERR "loop: Transfer error at byte offset %llu, "
"length %i.\n", (unsigned long long)pos, bvec->bv_len);
if (ret > 0)
ret = -EIO;
return ret;
}
static int lo_send(struct loop_device *lo, struct bio *bio, loff_t pos)
{
int (*do_lo_send)(struct loop_device *, struct bio_vec *, loff_t,
struct page *page);
struct bio_vec *bvec;
struct page *page = NULL;
int i, ret = 0;
if (lo->transfer != transfer_none) {
page = alloc_page(GFP_NOIO | __GFP_HIGHMEM);
if (unlikely(!page))
goto fail;
kmap(page);
do_lo_send = do_lo_send_write;
} else {
do_lo_send = do_lo_send_direct_write;
}
bio_for_each_segment(bvec, bio, i) {
ret = do_lo_send(lo, bvec, pos, page);
if (ret < 0)
break;
pos += bvec->bv_len;
}
if (page) {
kunmap(page);
__free_page(page);
}
out:
return ret;
fail:
printk(KERN_ERR "loop: Failed to allocate temporary page for write.\n");
ret = -ENOMEM;
goto out;
}
struct lo_read_data {
struct loop_device *lo;
struct page *page;
unsigned offset;
int bsize;
};
static int
lo_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf,
struct splice_desc *sd)
{
struct lo_read_data *p = sd->u.data;
struct loop_device *lo = p->lo;
struct page *page = buf->page;
sector_t IV;
int size;
IV = ((sector_t) page->index << (PAGE_CACHE_SHIFT - 9)) +
(buf->offset >> 9);
size = sd->len;
if (size > p->bsize)
size = p->bsize;
if (lo_do_transfer(lo, READ, page, buf->offset, p->page, p->offset, size, IV)) {
printk(KERN_ERR "loop: transfer error block %ld\n",
page->index);
size = -EINVAL;
}
flush_dcache_page(p->page);
if (size > 0)
p->offset += size;
return size;
}
static int
lo_direct_splice_actor(struct pipe_inode_info *pipe, struct splice_desc *sd)
{
return __splice_from_pipe(pipe, sd, lo_splice_actor);
}
static ssize_t
do_lo_receive(struct loop_device *lo,
struct bio_vec *bvec, int bsize, loff_t pos)
{
struct lo_read_data cookie;
struct splice_desc sd;
struct file *file;
ssize_t retval;
cookie.lo = lo;
cookie.page = bvec->bv_page;
cookie.offset = bvec->bv_offset;
cookie.bsize = bsize;
sd.len = 0;
sd.total_len = bvec->bv_len;
sd.flags = 0;
sd.pos = pos;
sd.u.data = &cookie;
file = lo->lo_backing_file;
retval = splice_direct_to_actor(file, &sd, lo_direct_splice_actor);
return retval;
}
static int
lo_receive(struct loop_device *lo, struct bio *bio, int bsize, loff_t pos)
{
struct bio_vec *bvec;
ssize_t s;
int i;
bio_for_each_segment(bvec, bio, i) {
s = do_lo_receive(lo, bvec, bsize, pos);
if (s < 0)
return s;
if (s != bvec->bv_len) {
zero_fill_bio(bio);
break;
}
pos += bvec->bv_len;
}
return 0;
}
static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
{
loff_t pos;
int ret;
pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
if (bio_rw(bio) == WRITE) {
struct file *file = lo->lo_backing_file;
if (bio->bi_rw & REQ_FLUSH) {
ret = vfs_fsync(file, 0);
if (unlikely(ret && ret != -EINVAL)) {
ret = -EIO;
goto out;
}
}
/*
* We use punch hole to reclaim the free space used by the
* image a.k.a. discard. However we do not support discard if
* encryption is enabled, because it may give an attacker
* useful information.
*/
if (bio->bi_rw & REQ_DISCARD) {
struct file *file = lo->lo_backing_file;
int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
if ((!file->f_op->fallocate) ||
lo->lo_encrypt_key_size) {
ret = -EOPNOTSUPP;
goto out;
}
ret = file->f_op->fallocate(file, mode, pos,
bio->bi_size);
if (unlikely(ret && ret != -EINVAL &&
ret != -EOPNOTSUPP))
ret = -EIO;
goto out;
}
ret = lo_send(lo, bio, pos);
if ((bio->bi_rw & REQ_FUA) && !ret) {
ret = vfs_fsync(file, 0);
if (unlikely(ret && ret != -EINVAL))
ret = -EIO;
}
} else
ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
out:
return ret;
}
/*
* Add bio to back of pending list
*/
static void loop_add_bio(struct loop_device *lo, struct bio *bio)
{
lo->lo_bio_count++;
bio_list_add(&lo->lo_bio_list, bio);
}
/*
* Grab first pending buffer
*/
static struct bio *loop_get_bio(struct loop_device *lo)
{
lo->lo_bio_count--;
return bio_list_pop(&lo->lo_bio_list);
}
static void loop_make_request(struct request_queue *q, struct bio *old_bio)
{
struct loop_device *lo = q->queuedata;
int rw = bio_rw(old_bio);
if (rw == READA)
rw = READ;
BUG_ON(!lo || (rw != READ && rw != WRITE));
spin_lock_irq(&lo->lo_lock);
if (lo->lo_state != Lo_bound)
goto out;
if (unlikely(rw == WRITE && (lo->lo_flags & LO_FLAGS_READ_ONLY)))
goto out;
if (lo->lo_bio_count >= q->nr_congestion_on)
wait_event_lock_irq(lo->lo_req_wait,
lo->lo_bio_count < q->nr_congestion_off,
lo->lo_lock);
loop_add_bio(lo, old_bio);
wake_up(&lo->lo_event);
spin_unlock_irq(&lo->lo_lock);
return;
out:
spin_unlock_irq(&lo->lo_lock);
bio_io_error(old_bio);
}
struct switch_request {
struct file *file;
struct completion wait;
};
static void do_loop_switch(struct loop_device *, struct switch_request *);
static inline void loop_handle_bio(struct loop_device *lo, struct bio *bio)
{
if (unlikely(!bio->bi_bdev)) {
do_loop_switch(lo, bio->bi_private);
bio_put(bio);
} else {
int ret = do_bio_filebacked(lo, bio);
bio_endio(bio, ret);
}
}
/*
* worker thread that handles reads/writes to file backed loop devices,
* to avoid blocking in our make_request_fn. it also does loop decrypting
* on reads for block backed loop, as that is too heavy to do from
* b_end_io context where irqs may be disabled.
*
* Loop explanation: loop_clr_fd() sets lo_state to Lo_rundown before
* calling kthread_stop(). Therefore once kthread_should_stop() is
* true, make_request will not place any more requests. Therefore
* once kthread_should_stop() is true and lo_bio is NULL, we are
* done with the loop.
*/
static int loop_thread(void *data)
{
struct loop_device *lo = data;
struct bio *bio;
set_user_nice(current, -20);
while (!kthread_should_stop() || !bio_list_empty(&lo->lo_bio_list)) {
wait_event_interruptible(lo->lo_event,
!bio_list_empty(&lo->lo_bio_list) ||
kthread_should_stop());
if (bio_list_empty(&lo->lo_bio_list))
continue;
spin_lock_irq(&lo->lo_lock);
bio = loop_get_bio(lo);
if (lo->lo_bio_count < lo->lo_queue->nr_congestion_off)
wake_up(&lo->lo_req_wait);
spin_unlock_irq(&lo->lo_lock);
BUG_ON(!bio);
loop_handle_bio(lo, bio);
}
return 0;
}
/*
* loop_switch performs the hard work of switching a backing store.
* First it needs to flush existing IO, it does this by sending a magic
* BIO down the pipe. The completion of this BIO does the actual switch.
*/
static int loop_switch(struct loop_device *lo, struct file *file)
{
struct switch_request w;
struct bio *bio = bio_alloc(GFP_KERNEL, 0);
if (!bio)
return -ENOMEM;
init_completion(&w.wait);
w.file = file;
bio->bi_private = &w;
bio->bi_bdev = NULL;
loop_make_request(lo->lo_queue, bio);
wait_for_completion(&w.wait);
return 0;
}
/*
* Helper to flush the IOs in loop, but keeping loop thread running
*/
static int loop_flush(struct loop_device *lo)
{
/* loop not yet configured, no running thread, nothing to flush */
if (!lo->lo_thread)
return 0;
return loop_switch(lo, NULL);
}
/*
* Do the actual switch; called from the BIO completion routine
*/
static void do_loop_switch(struct loop_device *lo, struct switch_request *p)
{
struct file *file = p->file;
struct file *old_file = lo->lo_backing_file;
struct address_space *mapping;
/* if no new file, only flush of queued bios requested */
if (!file)
goto out;
mapping = file->f_mapping;
mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
lo->lo_backing_file = file;
lo->lo_blocksize = S_ISBLK(mapping->host->i_mode) ?
mapping->host->i_bdev->bd_block_size : PAGE_SIZE;
lo->old_gfp_mask = mapping_gfp_mask(mapping);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
out:
complete(&p->wait);
}
/*
* loop_change_fd switched the backing store of a loopback device to
* a new file. This is useful for operating system installers to free up
* the original file and in High Availability environments to switch to
* an alternative location for the content in case of server meltdown.
* This can only work if the loop device is used read-only, and if the
* new backing store is the same size and type as the old backing store.
*/
static int loop_change_fd(struct loop_device *lo, struct block_device *bdev,
unsigned int arg)
{
struct file *file, *old_file;
struct inode *inode;
int error;
error = -ENXIO;
if (lo->lo_state != Lo_bound)
goto out;
/* the loop device has to be read-only */
error = -EINVAL;
if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
goto out;
error = -EBADF;
file = fget(arg);
if (!file)
goto out;
inode = file->f_mapping->host;
old_file = lo->lo_backing_file;
error = -EINVAL;
if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
goto out_putf;
/* size of the new backing store needs to be the same */
if (get_loop_size(lo, file) != get_loop_size(lo, old_file))
goto out_putf;
/* and ... switch */
error = loop_switch(lo, file);
if (error)
goto out_putf;
fput(old_file);
if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
return 0;
out_putf:
fput(file);
out:
return error;
}
static inline int is_loop_device(struct file *file)
{
struct inode *i = file->f_mapping->host;
return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == LOOP_MAJOR;
}
/* loop sysfs attributes */
static ssize_t loop_attr_show(struct device *dev, char *page,
ssize_t (*callback)(struct loop_device *, char *))
{
struct gendisk *disk = dev_to_disk(dev);
struct loop_device *lo = disk->private_data;
return callback(lo, page);
}
#define LOOP_ATTR_RO(_name) \
static ssize_t loop_attr_##_name##_show(struct loop_device *, char *); \
static ssize_t loop_attr_do_show_##_name(struct device *d, \
struct device_attribute *attr, char *b) \
{ \
return loop_attr_show(d, b, loop_attr_##_name##_show); \
} \
static struct device_attribute loop_attr_##_name = \
__ATTR(_name, S_IRUGO, loop_attr_do_show_##_name, NULL);
static ssize_t loop_attr_backing_file_show(struct loop_device *lo, char *buf)
{
ssize_t ret;
char *p = NULL;
spin_lock_irq(&lo->lo_lock);
if (lo->lo_backing_file)
p = d_path(&lo->lo_backing_file->f_path, buf, PAGE_SIZE - 1);
spin_unlock_irq(&lo->lo_lock);
if (IS_ERR_OR_NULL(p))
ret = PTR_ERR(p);
else {
ret = strlen(p);
memmove(buf, p, ret);
buf[ret++] = '\n';
buf[ret] = 0;
}
return ret;
}
static ssize_t loop_attr_offset_show(struct loop_device *lo, char *buf)
{
return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_offset);
}
static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
{
return sprintf(buf, "%llu\n", (unsigned long long)lo->lo_sizelimit);
}
static ssize_t loop_attr_autoclear_show(struct loop_device *lo, char *buf)
{
int autoclear = (lo->lo_flags & LO_FLAGS_AUTOCLEAR);
return sprintf(buf, "%s\n", autoclear ? "1" : "0");
}
static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf)
{
int partscan = (lo->lo_flags & LO_FLAGS_PARTSCAN);
return sprintf(buf, "%s\n", partscan ? "1" : "0");
}
LOOP_ATTR_RO(backing_file);
LOOP_ATTR_RO(offset);
LOOP_ATTR_RO(sizelimit);
LOOP_ATTR_RO(autoclear);
LOOP_ATTR_RO(partscan);
static struct attribute *loop_attrs[] = {
&loop_attr_backing_file.attr,
&loop_attr_offset.attr,
&loop_attr_sizelimit.attr,
&loop_attr_autoclear.attr,
&loop_attr_partscan.attr,
NULL,
};
static struct attribute_group loop_attribute_group = {
.name = "loop",
.attrs= loop_attrs,
};
static int loop_sysfs_init(struct loop_device *lo)
{
return sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
&loop_attribute_group);
}
static void loop_sysfs_exit(struct loop_device *lo)
{
sysfs_remove_group(&disk_to_dev(lo->lo_disk)->kobj,
&loop_attribute_group);
}
static void loop_config_discard(struct loop_device *lo)
{
struct file *file = lo->lo_backing_file;
struct inode *inode = file->f_mapping->host;
struct request_queue *q = lo->lo_queue;
/*
* We use punch hole to reclaim the free space used by the
* image a.k.a. discard. However we do support discard if
* encryption is enabled, because it may give an attacker
* useful information.
*/
if ((!file->f_op->fallocate) ||
lo->lo_encrypt_key_size) {
q->limits.discard_granularity = 0;
q->limits.discard_alignment = 0;
q->limits.max_discard_sectors = 0;
q->limits.discard_zeroes_data = 0;
queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
return;
}
q->limits.discard_granularity = inode->i_sb->s_blocksize;
q->limits.discard_alignment = 0;
q->limits.max_discard_sectors = UINT_MAX >> 9;
q->limits.discard_zeroes_data = 1;
queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
}
static int loop_set_fd(struct loop_device *lo, fmode_t mode,
struct block_device *bdev, unsigned int arg)
{
struct file *file, *f;
struct inode *inode;
struct address_space *mapping;
unsigned lo_blocksize;
int lo_flags = 0;
int error;
loff_t size;
/* This is safe, since we have a reference from open(). */
__module_get(THIS_MODULE);
error = -EBADF;
file = fget(arg);
if (!file)
goto out;
error = -EBUSY;
if (lo->lo_state != Lo_unbound)
goto out_putf;
/* Avoid recursion */
f = file;
while (is_loop_device(f)) {
struct loop_device *l;
if (f->f_mapping->host->i_bdev == bdev)
goto out_putf;
l = f->f_mapping->host->i_bdev->bd_disk->private_data;
if (l->lo_state == Lo_unbound) {
error = -EINVAL;
goto out_putf;
}
f = l->lo_backing_file;
}
mapping = file->f_mapping;
inode = mapping->host;
error = -EINVAL;
if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
goto out_putf;
if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
!file->f_op->write)
lo_flags |= LO_FLAGS_READ_ONLY;
lo_blocksize = S_ISBLK(inode->i_mode) ?
inode->i_bdev->bd_block_size : PAGE_SIZE;
error = -EFBIG;
size = get_loop_size(lo, file);
if ((loff_t)(sector_t)size != size)
goto out_putf;
error = 0;
set_device_ro(bdev, (lo_flags & LO_FLAGS_READ_ONLY) != 0);
lo->lo_blocksize = lo_blocksize;
lo->lo_device = bdev;
lo->lo_flags = lo_flags;
lo->lo_backing_file = file;
lo->transfer = transfer_none;
lo->ioctl = NULL;
lo->lo_sizelimit = 0;
lo->lo_bio_count = 0;
lo->old_gfp_mask = mapping_gfp_mask(mapping);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
bio_list_init(&lo->lo_bio_list);
/*
* set queue make_request_fn, and add limits based on lower level
* device
*/
blk_queue_make_request(lo->lo_queue, loop_make_request);
lo->lo_queue->queuedata = lo;
if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
blk_queue_flush(lo->lo_queue, REQ_FLUSH);
set_capacity(lo->lo_disk, size);
bd_set_size(bdev, size << 9);
loop_sysfs_init(lo);
/* let user-space know about the new size */
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
set_blocksize(bdev, lo_blocksize);
lo->lo_thread = kthread_create(loop_thread, lo, "loop%d",
lo->lo_number);
if (IS_ERR(lo->lo_thread)) {
error = PTR_ERR(lo->lo_thread);
goto out_clr;
}
lo->lo_state = Lo_bound;
wake_up_process(lo->lo_thread);
if (part_shift)
lo->lo_flags |= LO_FLAGS_PARTSCAN;
if (lo->lo_flags & LO_FLAGS_PARTSCAN)
ioctl_by_bdev(bdev, BLKRRPART, 0);
/* Grab the block_device to prevent its destruction after we
* put /dev/loopXX inode. Later in loop_clr_fd() we bdput(bdev).
*/
bdgrab(bdev);
return 0;
out_clr:
loop_sysfs_exit(lo);
lo->lo_thread = NULL;
lo->lo_device = NULL;
lo->lo_backing_file = NULL;
lo->lo_flags = 0;
set_capacity(lo->lo_disk, 0);
invalidate_bdev(bdev);
bd_set_size(bdev, 0);
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask);
lo->lo_state = Lo_unbound;
out_putf:
fput(file);
out:
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
return error;
}
static int
loop_release_xfer(struct loop_device *lo)
{
int err = 0;
struct loop_func_table *xfer = lo->lo_encryption;
if (xfer) {
if (xfer->release)
err = xfer->release(lo);
lo->transfer = NULL;
lo->lo_encryption = NULL;
module_put(xfer->owner);
}
return err;
}
static int
loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
const struct loop_info64 *i)
{
int err = 0;
if (xfer) {
struct module *owner = xfer->owner;
if (!try_module_get(owner))
return -EINVAL;
if (xfer->init)
err = xfer->init(lo, i);
if (err)
module_put(owner);
else
lo->lo_encryption = xfer;
}
return err;
}
static int loop_clr_fd(struct loop_device *lo)
{
struct file *filp = lo->lo_backing_file;
gfp_t gfp = lo->old_gfp_mask;
struct block_device *bdev = lo->lo_device;
if (lo->lo_state != Lo_bound)
return -ENXIO;
/*
* If we've explicitly asked to tear down the loop device,
* and it has an elevated reference count, set it for auto-teardown when
* the last reference goes away. This stops $!~#$@ udev from
* preventing teardown because it decided that it needs to run blkid on
* the loopback device whenever they appear. xfstests is notorious for
* failing tests because blkid via udev races with a losetup
* <dev>/do something like mkfs/losetup -d <dev> causing the losetup -d
* command to fail with EBUSY.
*/
if (lo->lo_refcnt > 1) {
lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
mutex_unlock(&lo->lo_ctl_mutex);
return 0;
}
if (filp == NULL)
return -EINVAL;
spin_lock_irq(&lo->lo_lock);
lo->lo_state = Lo_rundown;
spin_unlock_irq(&lo->lo_lock);
kthread_stop(lo->lo_thread);
spin_lock_irq(&lo->lo_lock);
lo->lo_backing_file = NULL;
spin_unlock_irq(&lo->lo_lock);
loop_release_xfer(lo);
lo->transfer = NULL;
lo->ioctl = NULL;
lo->lo_device = NULL;
lo->lo_encryption = NULL;
lo->lo_offset = 0;
lo->lo_sizelimit = 0;
lo->lo_encrypt_key_size = 0;
lo->lo_thread = NULL;
memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);
memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);
memset(lo->lo_file_name, 0, LO_NAME_SIZE);
if (bdev) {
bdput(bdev);
invalidate_bdev(bdev);
}
set_capacity(lo->lo_disk, 0);
loop_sysfs_exit(lo);
if (bdev) {
bd_set_size(bdev, 0);
/* let user-space know about this change */
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
}
mapping_set_gfp_mask(filp->f_mapping, gfp);
lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
if (lo->lo_flags & LO_FLAGS_PARTSCAN && bdev)
ioctl_by_bdev(bdev, BLKRRPART, 0);
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
mutex_unlock(&lo->lo_ctl_mutex);
/*
* Need not hold lo_ctl_mutex to fput backing file.
* Calling fput holding lo_ctl_mutex triggers a circular
* lock dependency possibility warning as fput can take
* bd_mutex which is usually taken before lo_ctl_mutex.
*/
fput(filp);
return 0;
}
static int
loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
{
int err;
struct loop_func_table *xfer;
kuid_t uid = current_uid();
if (lo->lo_encrypt_key_size &&
!uid_eq(lo->lo_key_owner, uid) &&
!capable(CAP_SYS_ADMIN))
return -EPERM;
if (lo->lo_state != Lo_bound)
return -ENXIO;
if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
return -EINVAL;
err = loop_release_xfer(lo);
if (err)
return err;
if (info->lo_encrypt_type) {
unsigned int type = info->lo_encrypt_type;
if (type >= MAX_LO_CRYPT)
return -EINVAL;
xfer = xfer_funcs[type];
if (xfer == NULL)
return -EINVAL;
} else
xfer = NULL;
err = loop_init_xfer(lo, xfer, info);
if (err)
return err;
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit)
if (figure_loop_size(lo, info->lo_offset, info->lo_sizelimit))
return -EFBIG;
loop_config_discard(lo);
memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE);
lo->lo_file_name[LO_NAME_SIZE-1] = 0;
lo->lo_crypt_name[LO_NAME_SIZE-1] = 0;
if (!xfer)
xfer = &none_funcs;
lo->transfer = xfer->transfer;
lo->ioctl = xfer->ioctl;
if ((lo->lo_flags & LO_FLAGS_AUTOCLEAR) !=
(info->lo_flags & LO_FLAGS_AUTOCLEAR))
lo->lo_flags ^= LO_FLAGS_AUTOCLEAR;
if ((info->lo_flags & LO_FLAGS_PARTSCAN) &&
!(lo->lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_flags |= LO_FLAGS_PARTSCAN;
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
ioctl_by_bdev(lo->lo_device, BLKRRPART, 0);
}
lo->lo_encrypt_key_size = info->lo_encrypt_key_size;
lo->lo_init[0] = info->lo_init[0];
lo->lo_init[1] = info->lo_init[1];
if (info->lo_encrypt_key_size) {
memcpy(lo->lo_encrypt_key, info->lo_encrypt_key,
info->lo_encrypt_key_size);
lo->lo_key_owner = uid;
}
return 0;
}
static int
loop_get_status(struct loop_device *lo, struct loop_info64 *info)
{
struct file *file = lo->lo_backing_file;
struct kstat stat;
int error;
if (lo->lo_state != Lo_bound)
return -ENXIO;
error = vfs_getattr(&file->f_path, &stat);
if (error)
return error;
memset(info, 0, sizeof(*info));
info->lo_number = lo->lo_number;
info->lo_device = huge_encode_dev(stat.dev);
info->lo_inode = stat.ino;
info->lo_rdevice = huge_encode_dev(lo->lo_device ? stat.rdev : stat.dev);
info->lo_offset = lo->lo_offset;
info->lo_sizelimit = lo->lo_sizelimit;
info->lo_flags = lo->lo_flags;
memcpy(info->lo_file_name, lo->lo_file_name, LO_NAME_SIZE);
memcpy(info->lo_crypt_name, lo->lo_crypt_name, LO_NAME_SIZE);
info->lo_encrypt_type =
lo->lo_encryption ? lo->lo_encryption->number : 0;
if (lo->lo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
info->lo_encrypt_key_size = lo->lo_encrypt_key_size;
memcpy(info->lo_encrypt_key, lo->lo_encrypt_key,
lo->lo_encrypt_key_size);
}
return 0;
}
static void
loop_info64_from_old(const struct loop_info *info, struct loop_info64 *info64)
{
memset(info64, 0, sizeof(*info64));
info64->lo_number = info->lo_number;
info64->lo_device = info->lo_device;
info64->lo_inode = info->lo_inode;
info64->lo_rdevice = info->lo_rdevice;
info64->lo_offset = info->lo_offset;
info64->lo_sizelimit = 0;
info64->lo_encrypt_type = info->lo_encrypt_type;
info64->lo_encrypt_key_size = info->lo_encrypt_key_size;
info64->lo_flags = info->lo_flags;
info64->lo_init[0] = info->lo_init[0];
info64->lo_init[1] = info->lo_init[1];
if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
memcpy(info64->lo_crypt_name, info->lo_name, LO_NAME_SIZE);
else
memcpy(info64->lo_file_name, info->lo_name, LO_NAME_SIZE);
memcpy(info64->lo_encrypt_key, info->lo_encrypt_key, LO_KEY_SIZE);
}
static int
loop_info64_to_old(const struct loop_info64 *info64, struct loop_info *info)
{
memset(info, 0, sizeof(*info));
info->lo_number = info64->lo_number;
info->lo_device = info64->lo_device;
info->lo_inode = info64->lo_inode;
info->lo_rdevice = info64->lo_rdevice;
info->lo_offset = info64->lo_offset;
info->lo_encrypt_type = info64->lo_encrypt_type;
info->lo_encrypt_key_size = info64->lo_encrypt_key_size;
info->lo_flags = info64->lo_flags;
info->lo_init[0] = info64->lo_init[0];
info->lo_init[1] = info64->lo_init[1];
if (info->lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
memcpy(info->lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
else
memcpy(info->lo_name, info64->lo_file_name, LO_NAME_SIZE);
memcpy(info->lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
/* error in case values were truncated */
if (info->lo_device != info64->lo_device ||
info->lo_rdevice != info64->lo_rdevice ||
info->lo_inode != info64->lo_inode ||
info->lo_offset != info64->lo_offset)
return -EOVERFLOW;
return 0;
}
static int
loop_set_status_old(struct loop_device *lo, const struct loop_info __user *arg)
{
struct loop_info info;
struct loop_info64 info64;
if (copy_from_user(&info, arg, sizeof (struct loop_info)))
return -EFAULT;
loop_info64_from_old(&info, &info64);
return loop_set_status(lo, &info64);
}
static int
loop_set_status64(struct loop_device *lo, const struct loop_info64 __user *arg)
{
struct loop_info64 info64;
if (copy_from_user(&info64, arg, sizeof (struct loop_info64)))
return -EFAULT;
return loop_set_status(lo, &info64);
}
static int
loop_get_status_old(struct loop_device *lo, struct loop_info __user *arg) {
struct loop_info info;
struct loop_info64 info64;
int err = 0;
if (!arg)
err = -EINVAL;
if (!err)
err = loop_get_status(lo, &info64);
if (!err)
err = loop_info64_to_old(&info64, &info);
if (!err && copy_to_user(arg, &info, sizeof(info)))
err = -EFAULT;
return err;
}
static int
loop_get_status64(struct loop_device *lo, struct loop_info64 __user *arg) {
struct loop_info64 info64;
int err = 0;
if (!arg)
err = -EINVAL;
if (!err)
err = loop_get_status(lo, &info64);
if (!err && copy_to_user(arg, &info64, sizeof(info64)))
err = -EFAULT;
return err;
}
static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev)
{
if (unlikely(lo->lo_state != Lo_bound))
return -ENXIO;
return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);
}
static int lo_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct loop_device *lo = bdev->bd_disk->private_data;
int err;
mutex_lock_nested(&lo->lo_ctl_mutex, 1);
switch (cmd) {
case LOOP_SET_FD:
err = loop_set_fd(lo, mode, bdev, arg);
break;
case LOOP_CHANGE_FD:
err = loop_change_fd(lo, bdev, arg);
break;
case LOOP_CLR_FD:
/* loop_clr_fd would have unlocked lo_ctl_mutex on success */
err = loop_clr_fd(lo);
if (!err)
goto out_unlocked;
break;
case LOOP_SET_STATUS:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
err = loop_set_status_old(lo,
(struct loop_info __user *)arg);
break;
case LOOP_GET_STATUS:
err = loop_get_status_old(lo, (struct loop_info __user *) arg);
break;
case LOOP_SET_STATUS64:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
err = loop_set_status64(lo,
(struct loop_info64 __user *) arg);
break;
case LOOP_GET_STATUS64:
err = loop_get_status64(lo, (struct loop_info64 __user *) arg);
break;
case LOOP_SET_CAPACITY:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
err = loop_set_capacity(lo, bdev);
break;
default:
err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
}
mutex_unlock(&lo->lo_ctl_mutex);
out_unlocked:
return err;
}
#ifdef CONFIG_COMPAT
struct compat_loop_info {
compat_int_t lo_number; /* ioctl r/o */
compat_dev_t lo_device; /* ioctl r/o */
compat_ulong_t lo_inode; /* ioctl r/o */
compat_dev_t lo_rdevice; /* ioctl r/o */
compat_int_t lo_offset;
compat_int_t lo_encrypt_type;
compat_int_t lo_encrypt_key_size; /* ioctl w/o */
compat_int_t lo_flags; /* ioctl r/o */
char lo_name[LO_NAME_SIZE];
unsigned char lo_encrypt_key[LO_KEY_SIZE]; /* ioctl w/o */
compat_ulong_t lo_init[2];
char reserved[4];
};
/*
* Transfer 32-bit compatibility structure in userspace to 64-bit loop info
* - noinlined to reduce stack space usage in main part of driver
*/
static noinline int
loop_info64_from_compat(const struct compat_loop_info __user *arg,
struct loop_info64 *info64)
{
struct compat_loop_info info;
if (copy_from_user(&info, arg, sizeof(info)))
return -EFAULT;
memset(info64, 0, sizeof(*info64));
info64->lo_number = info.lo_number;
info64->lo_device = info.lo_device;
info64->lo_inode = info.lo_inode;
info64->lo_rdevice = info.lo_rdevice;
info64->lo_offset = info.lo_offset;
info64->lo_sizelimit = 0;
info64->lo_encrypt_type = info.lo_encrypt_type;
info64->lo_encrypt_key_size = info.lo_encrypt_key_size;
info64->lo_flags = info.lo_flags;
info64->lo_init[0] = info.lo_init[0];
info64->lo_init[1] = info.lo_init[1];
if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
memcpy(info64->lo_crypt_name, info.lo_name, LO_NAME_SIZE);
else
memcpy(info64->lo_file_name, info.lo_name, LO_NAME_SIZE);
memcpy(info64->lo_encrypt_key, info.lo_encrypt_key, LO_KEY_SIZE);
return 0;
}
/*
* Transfer 64-bit loop info to 32-bit compatibility structure in userspace
* - noinlined to reduce stack space usage in main part of driver
*/
static noinline int
loop_info64_to_compat(const struct loop_info64 *info64,
struct compat_loop_info __user *arg)
{
struct compat_loop_info info;
memset(&info, 0, sizeof(info));
info.lo_number = info64->lo_number;
info.lo_device = info64->lo_device;
info.lo_inode = info64->lo_inode;
info.lo_rdevice = info64->lo_rdevice;
info.lo_offset = info64->lo_offset;
info.lo_encrypt_type = info64->lo_encrypt_type;
info.lo_encrypt_key_size = info64->lo_encrypt_key_size;
info.lo_flags = info64->lo_flags;
info.lo_init[0] = info64->lo_init[0];
info.lo_init[1] = info64->lo_init[1];
if (info.lo_encrypt_type == LO_CRYPT_CRYPTOAPI)
memcpy(info.lo_name, info64->lo_crypt_name, LO_NAME_SIZE);
else
memcpy(info.lo_name, info64->lo_file_name, LO_NAME_SIZE);
memcpy(info.lo_encrypt_key, info64->lo_encrypt_key, LO_KEY_SIZE);
/* error in case values were truncated */
if (info.lo_device != info64->lo_device ||
info.lo_rdevice != info64->lo_rdevice ||
info.lo_inode != info64->lo_inode ||
info.lo_offset != info64->lo_offset ||
info.lo_init[0] != info64->lo_init[0] ||
info.lo_init[1] != info64->lo_init[1])
return -EOVERFLOW;
if (copy_to_user(arg, &info, sizeof(info)))
return -EFAULT;
return 0;
}
static int
loop_set_status_compat(struct loop_device *lo,
const struct compat_loop_info __user *arg)
{
struct loop_info64 info64;
int ret;
ret = loop_info64_from_compat(arg, &info64);
if (ret < 0)
return ret;
return loop_set_status(lo, &info64);
}
static int
loop_get_status_compat(struct loop_device *lo,
struct compat_loop_info __user *arg)
{
struct loop_info64 info64;
int err = 0;
if (!arg)
err = -EINVAL;
if (!err)
err = loop_get_status(lo, &info64);
if (!err)
err = loop_info64_to_compat(&info64, arg);
return err;
}
static int lo_compat_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct loop_device *lo = bdev->bd_disk->private_data;
int err;
switch(cmd) {
case LOOP_SET_STATUS:
mutex_lock(&lo->lo_ctl_mutex);
err = loop_set_status_compat(
lo, (const struct compat_loop_info __user *) arg);
mutex_unlock(&lo->lo_ctl_mutex);
break;
case LOOP_GET_STATUS:
mutex_lock(&lo->lo_ctl_mutex);
err = loop_get_status_compat(
lo, (struct compat_loop_info __user *) arg);
mutex_unlock(&lo->lo_ctl_mutex);
break;
case LOOP_SET_CAPACITY:
case LOOP_CLR_FD:
case LOOP_GET_STATUS64:
case LOOP_SET_STATUS64:
arg = (unsigned long) compat_ptr(arg);
case LOOP_SET_FD:
case LOOP_CHANGE_FD:
err = lo_ioctl(bdev, mode, cmd, arg);
break;
default:
err = -ENOIOCTLCMD;
break;
}
return err;
}
#endif
static int lo_open(struct block_device *bdev, fmode_t mode)
{
struct loop_device *lo;
int err = 0;
mutex_lock(&loop_index_mutex);
lo = bdev->bd_disk->private_data;
if (!lo) {
err = -ENXIO;
goto out;
}
mutex_lock(&lo->lo_ctl_mutex);
lo->lo_refcnt++;
mutex_unlock(&lo->lo_ctl_mutex);
out:
mutex_unlock(&loop_index_mutex);
return err;
}
static void lo_release(struct gendisk *disk, fmode_t mode)
{
struct loop_device *lo = disk->private_data;
int err;
mutex_lock(&lo->lo_ctl_mutex);
if (--lo->lo_refcnt)
goto out;
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
/*
* In autoclear mode, stop the loop thread
* and remove configuration after last close.
*/
err = loop_clr_fd(lo);
if (!err)
return;
} else {
/*
* Otherwise keep thread (if running) and config,
* but flush possible ongoing bios in thread.
*/
loop_flush(lo);
}
out:
mutex_unlock(&lo->lo_ctl_mutex);
}
static const struct block_device_operations lo_fops = {
.owner = THIS_MODULE,
.open = lo_open,
.release = lo_release,
.ioctl = lo_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = lo_compat_ioctl,
#endif
};
/*
* And now the modules code and kernel interface.
*/
static int max_loop;
module_param(max_loop, int, S_IRUGO);
MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
module_param(max_part, int, S_IRUGO);
MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
int loop_register_transfer(struct loop_func_table *funcs)
{
unsigned int n = funcs->number;
if (n >= MAX_LO_CRYPT || xfer_funcs[n])
return -EINVAL;
xfer_funcs[n] = funcs;
return 0;
}
static int unregister_transfer_cb(int id, void *ptr, void *data)
{
struct loop_device *lo = ptr;
struct loop_func_table *xfer = data;
mutex_lock(&lo->lo_ctl_mutex);
if (lo->lo_encryption == xfer)
loop_release_xfer(lo);
mutex_unlock(&lo->lo_ctl_mutex);
return 0;
}
int loop_unregister_transfer(int number)
{
unsigned int n = number;
struct loop_func_table *xfer;
if (n == 0 || n >= MAX_LO_CRYPT || (xfer = xfer_funcs[n]) == NULL)
return -EINVAL;
xfer_funcs[n] = NULL;
idr_for_each(&loop_index_idr, &unregister_transfer_cb, xfer);
return 0;
}
EXPORT_SYMBOL(loop_register_transfer);
EXPORT_SYMBOL(loop_unregister_transfer);
static int loop_add(struct loop_device **l, int i)
{
struct loop_device *lo;
struct gendisk *disk;
int err;
err = -ENOMEM;
lo = kzalloc(sizeof(*lo), GFP_KERNEL);
if (!lo)
goto out;
/* allocate id, if @id >= 0, we're requesting that specific id */
if (i >= 0) {
err = idr_alloc(&loop_index_idr, lo, i, i + 1, GFP_KERNEL);
if (err == -ENOSPC)
err = -EEXIST;
} else {
err = idr_alloc(&loop_index_idr, lo, 0, 0, GFP_KERNEL);
}
if (err < 0)
goto out_free_dev;
i = err;
err = -ENOMEM;
lo->lo_queue = blk_alloc_queue(GFP_KERNEL);
if (!lo->lo_queue)
goto out_free_dev;
disk = lo->lo_disk = alloc_disk(1 << part_shift);
if (!disk)
goto out_free_queue;
/*
* Disable partition scanning by default. The in-kernel partition
* scanning can be requested individually per-device during its
* setup. Userspace can always add and remove partitions from all
* devices. The needed partition minors are allocated from the
* extended minor space, the main loop device numbers will continue
* to match the loop minors, regardless of the number of partitions
* used.
*
* If max_part is given, partition scanning is globally enabled for
* all loop devices. The minors for the main loop devices will be
* multiples of max_part.
*
* Note: Global-for-all-devices, set-only-at-init, read-only module
* parameteters like 'max_loop' and 'max_part' make things needlessly
* complicated, are too static, inflexible and may surprise
* userspace tools. Parameters like this in general should be avoided.
*/
if (!part_shift)
disk->flags |= GENHD_FL_NO_PART_SCAN;
disk->flags |= GENHD_FL_EXT_DEVT;
mutex_init(&lo->lo_ctl_mutex);
lo->lo_number = i;
lo->lo_thread = NULL;
init_waitqueue_head(&lo->lo_event);
init_waitqueue_head(&lo->lo_req_wait);
spin_lock_init(&lo->lo_lock);
disk->major = LOOP_MAJOR;
disk->first_minor = i << part_shift;
disk->fops = &lo_fops;
disk->private_data = lo;
disk->queue = lo->lo_queue;
sprintf(disk->disk_name, "loop%d", i);
add_disk(disk);
*l = lo;
return lo->lo_number;
out_free_queue:
blk_cleanup_queue(lo->lo_queue);
out_free_dev:
kfree(lo);
out:
return err;
}
static void loop_remove(struct loop_device *lo)
{
del_gendisk(lo->lo_disk);
blk_cleanup_queue(lo->lo_queue);
put_disk(lo->lo_disk);
kfree(lo);
}
static int find_free_cb(int id, void *ptr, void *data)
{
struct loop_device *lo = ptr;
struct loop_device **l = data;
if (lo->lo_state == Lo_unbound) {
*l = lo;
return 1;
}
return 0;
}
static int loop_lookup(struct loop_device **l, int i)
{
struct loop_device *lo;
int ret = -ENODEV;
if (i < 0) {
int err;
err = idr_for_each(&loop_index_idr, &find_free_cb, &lo);
if (err == 1) {
*l = lo;
ret = lo->lo_number;
}
goto out;
}
/* lookup and return a specific i */
lo = idr_find(&loop_index_idr, i);
if (lo) {
*l = lo;
ret = lo->lo_number;
}
out:
return ret;
}
static struct kobject *loop_probe(dev_t dev, int *part, void *data)
{
struct loop_device *lo;
struct kobject *kobj;
int err;
mutex_lock(&loop_index_mutex);
err = loop_lookup(&lo, MINOR(dev) >> part_shift);
if (err < 0)
err = loop_add(&lo, MINOR(dev) >> part_shift);
if (err < 0)
kobj = ERR_PTR(err);
else
kobj = get_disk(lo->lo_disk);
mutex_unlock(&loop_index_mutex);
*part = 0;
return kobj;
}
static long loop_control_ioctl(struct file *file, unsigned int cmd,
unsigned long parm)
{
struct loop_device *lo;
int ret = -ENOSYS;
mutex_lock(&loop_index_mutex);
switch (cmd) {
case LOOP_CTL_ADD:
ret = loop_lookup(&lo, parm);
if (ret >= 0) {
ret = -EEXIST;
break;
}
ret = loop_add(&lo, parm);
break;
case LOOP_CTL_REMOVE:
ret = loop_lookup(&lo, parm);
if (ret < 0)
break;
mutex_lock(&lo->lo_ctl_mutex);
if (lo->lo_state != Lo_unbound) {
ret = -EBUSY;
mutex_unlock(&lo->lo_ctl_mutex);
break;
}
if (lo->lo_refcnt > 0) {
ret = -EBUSY;
mutex_unlock(&lo->lo_ctl_mutex);
break;
}
lo->lo_disk->private_data = NULL;
mutex_unlock(&lo->lo_ctl_mutex);
idr_remove(&loop_index_idr, lo->lo_number);
loop_remove(lo);
break;
case LOOP_CTL_GET_FREE:
ret = loop_lookup(&lo, -1);
if (ret >= 0)
break;
ret = loop_add(&lo, -1);
}
mutex_unlock(&loop_index_mutex);
return ret;
}
static const struct file_operations loop_ctl_fops = {
.open = nonseekable_open,
.unlocked_ioctl = loop_control_ioctl,
.compat_ioctl = loop_control_ioctl,
.owner = THIS_MODULE,
.llseek = noop_llseek,
};
static struct miscdevice loop_misc = {
.minor = LOOP_CTRL_MINOR,
.name = "loop-control",
.fops = &loop_ctl_fops,
};
MODULE_ALIAS_MISCDEV(LOOP_CTRL_MINOR);
MODULE_ALIAS("devname:loop-control");
static int __init loop_init(void)
{
int i, nr;
unsigned long range;
struct loop_device *lo;
int err;
err = misc_register(&loop_misc);
if (err < 0)
return err;
part_shift = 0;
if (max_part > 0) {
part_shift = fls(max_part);
/*
* Adjust max_part according to part_shift as it is exported
* to user space so that user can decide correct minor number
* if [s]he want to create more devices.
*
* Note that -1 is required because partition 0 is reserved
* for the whole disk.
*/
max_part = (1UL << part_shift) - 1;
}
if ((1UL << part_shift) > DISK_MAX_PARTS) {
err = -EINVAL;
goto misc_out;
}
if (max_loop > 1UL << (MINORBITS - part_shift)) {
err = -EINVAL;
goto misc_out;
}
/*
* If max_loop is specified, create that many devices upfront.
* This also becomes a hard limit. If max_loop is not specified,
* create CONFIG_BLK_DEV_LOOP_MIN_COUNT loop devices at module
* init time. Loop devices can be requested on-demand with the
* /dev/loop-control interface, or be instantiated by accessing
* a 'dead' device node.
*/
if (max_loop) {
nr = max_loop;
range = max_loop << part_shift;
} else {
nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
range = 1UL << MINORBITS;
}
if (register_blkdev(LOOP_MAJOR, "loop")) {
err = -EIO;
goto misc_out;
}
blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
THIS_MODULE, loop_probe, NULL, NULL);
/* pre-create number of devices given by config or max_loop */
mutex_lock(&loop_index_mutex);
for (i = 0; i < nr; i++)
loop_add(&lo, i);
mutex_unlock(&loop_index_mutex);
printk(KERN_INFO "loop: module loaded\n");
return 0;
misc_out:
misc_deregister(&loop_misc);
return err;
}
static int loop_exit_cb(int id, void *ptr, void *data)
{
struct loop_device *lo = ptr;
loop_remove(lo);
return 0;
}
static void __exit loop_exit(void)
{
unsigned long range;
range = max_loop ? max_loop << part_shift : 1UL << MINORBITS;
idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
idr_destroy(&loop_index_idr);
blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
unregister_blkdev(LOOP_MAJOR, "loop");
misc_deregister(&loop_misc);
}
module_init(loop_init);
module_exit(loop_exit);
#ifndef MODULE
static int __init max_loop_setup(char *str)
{
max_loop = simple_strtol(str, NULL, 0);
return 1;
}
__setup("max_loop=", max_loop_setup);
#endif