On 11/02/2013 03:50 PM, Dave Kleikamp wrote:
> On 11/01/2013 03:53 PM, Jens Axboe wrote:
>> So we've three immediate options:
>>
>> 1) You base it on top of the block tree
>> 2) I carry the loop updates
>> 3) You hand Stephen a merge patch for the resulting merge of the two
>
> Attached is a merge patch and the merged loop.c. I'm having problems
> with the loop driver with both the block and my tree. I'll continue to
> look at that, but everything should build cleanly with this.
Looking back, I obviously rushed the last patch out. This merge patch,
and the resulting loop.c, fix my problem. My code is working with Jens'
block tree now.
Jens,
I ended up replacing a call to bio_iovec_idx() with __bvec_iter_bvec()
since the former was removed. It's not very elegant, but it works. I'm
open to suggestions on a cleaner fix, but it can wait until one or both
of these trees is merged.
I'll be out next week away from internet access, so I'm looking at the
later half of the merge window.
Thanks,
Shaggy
diff --cc drivers/block/loop.c
index e564769,33fde3a..0000000
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@@ -219,48 -218,6 +219,48 @@@ lo_do_transfer(struct loop_device *lo,
return lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
}
+#ifdef CONFIG_AIO
+static void lo_rw_aio_complete(u64 data, long res)
+{
+ struct bio *bio = (struct bio *)(uintptr_t)data;
+
+ if (res > 0)
+ res = 0;
+ else if (res < 0)
+ res = -EIO;
+
+ bio_endio(bio, res);
+}
+
+static int lo_rw_aio(struct loop_device *lo, struct bio *bio)
+{
+ struct file *file = lo->lo_backing_file;
+ struct kiocb *iocb;
+ unsigned int op;
+ struct iov_iter iter;
+ struct bio_vec *bvec;
+ size_t nr_segs;
- loff_t pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
++ loff_t pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
+
+ iocb = aio_kernel_alloc(GFP_NOIO);
+ if (!iocb)
+ return -ENOMEM;
+
+ if (bio_rw(bio) & WRITE)
+ op = IOCB_CMD_WRITE_ITER;
+ else
+ op = IOCB_CMD_READ_ITER;
+
- bvec = bio_iovec_idx(bio, bio->bi_idx);
++ bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
+ nr_segs = bio_segments(bio);
+ iov_iter_init_bvec(&iter, bvec, nr_segs, bvec_length(bvec, nr_segs), 0);
+ aio_kernel_init_rw(iocb, file, iov_iter_count(&iter), pos);
+ aio_kernel_init_callback(iocb, lo_rw_aio_complete, (u64)(uintptr_t)bio);
+
+ return aio_kernel_submit(iocb, op, &iter);
+}
+#endif /* CONFIG_AIO */
+
/**
* __do_lo_send_write - helper for writing data to a loop device
*
@@@ -458,36 -416,53 +459,36 @@@ static int do_bio_filebacked(struct loo
loff_t pos;
int ret;
- pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
+ pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
if (bio_rw(bio) == WRITE) {
- struct file *file = lo->lo_backing_file;
+ ret = lo_send(lo, bio, pos);
+ } else
+ ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
- if (bio->bi_rw & REQ_FLUSH) {
- ret = vfs_fsync(file, 0);
- if (unlikely(ret && ret != -EINVAL)) {
- ret = -EIO;
- goto out;
- }
- }
+ return ret;
+}
- /*
- * 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_iter.bi_size);
- if (unlikely(ret && ret != -EINVAL &&
- ret != -EOPNOTSUPP))
- ret = -EIO;
- goto out;
- }
+static int lo_discard(struct loop_device *lo, struct bio *bio)
+{
+ struct file *file = lo->lo_backing_file;
+ int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
- loff_t pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
++ loff_t pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
+ int ret;
- ret = lo_send(lo, bio, pos);
+ /*
+ * 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_FUA) && !ret) {
- ret = vfs_fsync(file, 0);
- if (unlikely(ret && ret != -EINVAL))
- ret = -EIO;
- }
- } else
- ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
+ if ((!file->f_op->fallocate) || lo->lo_encrypt_key_size)
+ return -EOPNOTSUPP;
- ret = file->f_op->fallocate(file, mode, pos, bio->bi_size);
-out:
++ ret = file->f_op->fallocate(file, mode, pos, bio->bi_iter.bi_size);
+ if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
+ ret = -EIO;
return ret;
}
/*
* 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@xxxxxxx Mar 20, 1997
*
* Added devfs support - Richard Gooch <rgooch@xxxxxxxxxxxxx> 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@xxxxxxxxxx
*
* Maximum number of loop devices now dynamic via max_loop module parameter.
* Russell Kroll <rkroll@xxxxxxxxxxxx> 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@xxxxxxxxxx>, 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@xxxxxxx>, Nov 2000
*
* Support up to 256 loop devices
* Heinz Mauelshagen <mge@xxxxxxxxxxx>, 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/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 <linux/aio.h>
#include "loop.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);
}
#ifdef CONFIG_AIO
static void lo_rw_aio_complete(u64 data, long res)
{
struct bio *bio = (struct bio *)(uintptr_t)data;
if (res > 0)
res = 0;
else if (res < 0)
res = -EIO;
bio_endio(bio, res);
}
static int lo_rw_aio(struct loop_device *lo, struct bio *bio)
{
struct file *file = lo->lo_backing_file;
struct kiocb *iocb;
unsigned int op;
struct iov_iter iter;
struct bio_vec *bvec;
size_t nr_segs;
loff_t pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
iocb = aio_kernel_alloc(GFP_NOIO);
if (!iocb)
return -ENOMEM;
if (bio_rw(bio) & WRITE)
op = IOCB_CMD_WRITE_ITER;
else
op = IOCB_CMD_READ_ITER;
bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
nr_segs = bio_segments(bio);
iov_iter_init_bvec(&iter, bvec, nr_segs, bvec_length(bvec, nr_segs), 0);
aio_kernel_init_rw(iocb, file, iov_iter_count(&iter), pos);
aio_kernel_init_callback(iocb, lo_rw_aio_complete, (u64)(uintptr_t)bio);
return aio_kernel_submit(iocb, op, &iter);
}
#endif /* CONFIG_AIO */
/**
* __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 bvec_iter iter;
struct page *page = NULL;
int 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, iter) {
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;
struct bvec_iter iter;
ssize_t s;
bio_for_each_segment(bvec, bio, iter) {
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_iter.bi_sector << 9) + lo->lo_offset;
if (bio_rw(bio) == WRITE) {
ret = lo_send(lo, bio, pos);
} else
ret = lo_receive(lo, bio, lo->lo_blocksize, pos);
return ret;
}
static int lo_discard(struct loop_device *lo, struct bio *bio)
{
struct file *file = lo->lo_backing_file;
int mode = FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE;
loff_t pos = ((loff_t) bio->bi_iter.bi_sector << 9) + lo->lo_offset;
int ret;
/*
* 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 ((!file->f_op->fallocate) || lo->lo_encrypt_key_size)
return -EOPNOTSUPP;
ret = file->f_op->fallocate(file, mode, pos, bio->bi_iter.bi_size);
if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
ret = -EIO;
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;
if (bio_rw(bio) == WRITE) {
if (bio->bi_rw & REQ_FLUSH) {
ret = vfs_fsync(lo->lo_backing_file, 1);
if (unlikely(ret && ret != -EINVAL))
goto out;
}
if (bio->bi_rw & REQ_DISCARD) {
ret = lo_discard(lo, bio);
goto out;
}
}
#ifdef CONFIG_AIO
if (lo->lo_flags & LO_FLAGS_USE_AIO &&
lo->transfer == transfer_none) {
ret = lo_rw_aio(lo, bio);
if (ret == 0)
return;
} else
#endif
ret = do_bio_filebacked(lo, bio);
if ((bio_rw(bio) == WRITE) && bio->bi_rw & REQ_FUA && !ret) {
ret = vfs_fsync(lo->lo_backing_file, 0);
if (unlikely(ret && ret != -EINVAL))
ret = -EIO;
}
out:
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;
/*
* In cases where the underlying filesystem calls balance_dirty_pages()
* we want less throttling to avoid lock ups trying to write dirty
* pages through the loop device
*/
current->flags |= PF_LESS_THROTTLE;
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;
#ifdef CONFIG_AIO
if (file->f_op->write_iter && file->f_op->read_iter &&
mapping->a_ops->direct_IO) {
file->f_flags |= O_DIRECT;
lo_flags |= LO_FLAGS_USE_AIO;
}
#endif
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);
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);
#ifdef CONFIG_AIO
/*
* We must not send too-small direct-io requests, so we inherit
* the logical block size from the underlying device
*/
if ((lo_flags & LO_FLAGS_USE_AIO) && inode->i_sb->s_bdev)
blk_queue_logical_block_size(lo->lo_queue,
bdev_logical_block_size(inode->i_sb->s_bdev));
#endif
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;
lo->lo_state = Lo_unbound;
/* 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_idr;
/*
* set queue make_request_fn
*/
blk_queue_make_request(lo->lo_queue, loop_make_request);
lo->lo_queue->queuedata = lo;
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_idr:
idr_remove(&loop_index_idr, i);
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 = NULL;
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
