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WSL2-Linux-Kernel/drivers/block/loop.c

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C
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/*
* 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/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/uio.h>
#include <linux/ioprio.h>
#include <linux/blk-cgroup.h>
#include "loop.h"
#include <linux/uaccess.h>
static DEFINE_IDR(loop_index_idr);
static DEFINE_MUTEX(loop_ctl_mutex);
static int max_part;
static int part_shift;
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,
};
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 void __loop_update_dio(struct loop_device *lo, bool dio)
{
struct file *file = lo->lo_backing_file;
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
unsigned short sb_bsize = 0;
unsigned dio_align = 0;
bool use_dio;
if (inode->i_sb->s_bdev) {
sb_bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
dio_align = sb_bsize - 1;
}
/*
* We support direct I/O only if lo_offset is aligned with the
* logical I/O size of backing device, and the logical block
* size of loop is bigger than the backing device's and the loop
* needn't transform transfer.
*
* TODO: the above condition may be loosed in the future, and
* direct I/O may be switched runtime at that time because most
* of requests in sane applications should be PAGE_SIZE aligned
*/
if (dio) {
if (queue_logical_block_size(lo->lo_queue) >= sb_bsize &&
!(lo->lo_offset & dio_align) &&
mapping->a_ops->direct_IO &&
!lo->transfer)
use_dio = true;
else
use_dio = false;
} else {
use_dio = false;
}
if (lo->use_dio == use_dio)
return;
/* flush dirty pages before changing direct IO */
vfs_fsync(file, 0);
/*
* The flag of LO_FLAGS_DIRECT_IO is handled similarly with
* LO_FLAGS_READ_ONLY, both are set from kernel, and losetup
* will get updated by ioctl(LOOP_GET_STATUS)
*/
if (lo->lo_state == Lo_bound)
blk_mq_freeze_queue(lo->lo_queue);
lo->use_dio = use_dio;
if (use_dio) {
blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, lo->lo_queue);
lo->lo_flags |= LO_FLAGS_DIRECT_IO;
} else {
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
lo->lo_flags &= ~LO_FLAGS_DIRECT_IO;
}
if (lo->lo_state == Lo_bound)
blk_mq_unfreeze_queue(lo->lo_queue);
}
/**
* loop_validate_block_size() - validates the passed in block size
* @bsize: size to validate
*/
static int
loop_validate_block_size(unsigned short bsize)
{
if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
return -EINVAL;
return 0;
}
/**
* loop_set_size() - sets device size and notifies userspace
* @lo: struct loop_device to set the size for
* @size: new size of the loop device
*
* Callers must validate that the size passed into this function fits into
* a sector_t, eg using loop_validate_size()
*/
static void loop_set_size(struct loop_device *lo, loff_t size)
{
if (!set_capacity_and_notify(lo->lo_disk, size))
kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
}
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)
{
int ret;
ret = lo->transfer(lo, cmd, rpage, roffs, lpage, loffs, size, rblock);
if (likely(!ret))
return 0;
printk_ratelimited(KERN_ERR
"loop: Transfer error at byte offset %llu, length %i.\n",
(unsigned long long)rblock << 9, size);
return ret;
}
static int lo_write_bvec(struct file *file, struct bio_vec *bvec, loff_t *ppos)
{
struct iov_iter i;
ssize_t bw;
iov_iter_bvec(&i, WRITE, bvec, 1, bvec->bv_len);
file_start_write(file);
bw = vfs_iter_write(file, &i, ppos, 0);
file_end_write(file);
if (likely(bw == bvec->bv_len))
return 0;
printk_ratelimited(KERN_ERR
"loop: Write error at byte offset %llu, length %i.\n",
(unsigned long long)*ppos, bvec->bv_len);
if (bw >= 0)
bw = -EIO;
return bw;
}
static int lo_write_simple(struct loop_device *lo, struct request *rq,
loff_t pos)
{
struct bio_vec bvec;
struct req_iterator iter;
int ret = 0;
rq_for_each_segment(bvec, rq, iter) {
ret = lo_write_bvec(lo->lo_backing_file, &bvec, &pos);
if (ret < 0)
break;
cond_resched();
}
return ret;
}
/*
* 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 lo_write_transfer(struct loop_device *lo, struct request *rq,
loff_t pos)
{
struct bio_vec bvec, b;
struct req_iterator iter;
struct page *page;
int ret = 0;
page = alloc_page(GFP_NOIO);
if (unlikely(!page))
return -ENOMEM;
rq_for_each_segment(bvec, rq, iter) {
ret = lo_do_transfer(lo, WRITE, page, 0, bvec.bv_page,
bvec.bv_offset, bvec.bv_len, pos >> 9);
if (unlikely(ret))
break;
b.bv_page = page;
b.bv_offset = 0;
b.bv_len = bvec.bv_len;
ret = lo_write_bvec(lo->lo_backing_file, &b, &pos);
if (ret < 0)
break;
}
__free_page(page);
return ret;
}
static int lo_read_simple(struct loop_device *lo, struct request *rq,
loff_t pos)
{
struct bio_vec bvec;
struct req_iterator iter;
struct iov_iter i;
ssize_t len;
rq_for_each_segment(bvec, rq, iter) {
iov_iter_bvec(&i, READ, &bvec, 1, bvec.bv_len);
len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
if (len < 0)
return len;
flush_dcache_page(bvec.bv_page);
if (len != bvec.bv_len) {
struct bio *bio;
__rq_for_each_bio(bio, rq)
zero_fill_bio(bio);
break;
}
cond_resched();
}
return 0;
}
static int lo_read_transfer(struct loop_device *lo, struct request *rq,
loff_t pos)
{
struct bio_vec bvec, b;
struct req_iterator iter;
struct iov_iter i;
struct page *page;
ssize_t len;
int ret = 0;
page = alloc_page(GFP_NOIO);
if (unlikely(!page))
return -ENOMEM;
rq_for_each_segment(bvec, rq, iter) {
loff_t offset = pos;
b.bv_page = page;
b.bv_offset = 0;
b.bv_len = bvec.bv_len;
iov_iter_bvec(&i, READ, &b, 1, b.bv_len);
len = vfs_iter_read(lo->lo_backing_file, &i, &pos, 0);
if (len < 0) {
ret = len;
goto out_free_page;
}
ret = lo_do_transfer(lo, READ, page, 0, bvec.bv_page,
bvec.bv_offset, len, offset >> 9);
if (ret)
goto out_free_page;
flush_dcache_page(bvec.bv_page);
if (len != bvec.bv_len) {
struct bio *bio;
__rq_for_each_bio(bio, rq)
zero_fill_bio(bio);
break;
}
}
ret = 0;
out_free_page:
__free_page(page);
return ret;
}
static int lo_fallocate(struct loop_device *lo, struct request *rq, loff_t pos,
int mode)
{
/*
* We use fallocate to manipulate the space mappings used by the image
* a.k.a. discard/zerorange. However we do not support this if
* encryption is enabled, because it may give an attacker useful
* information.
*/
struct file *file = lo->lo_backing_file;
struct request_queue *q = lo->lo_queue;
int ret;
mode |= FALLOC_FL_KEEP_SIZE;
if (!blk_queue_discard(q)) {
ret = -EOPNOTSUPP;
goto out;
}
ret = file->f_op->fallocate(file, mode, pos, blk_rq_bytes(rq));
if (unlikely(ret && ret != -EINVAL && ret != -EOPNOTSUPP))
ret = -EIO;
out:
return ret;
}
static int lo_req_flush(struct loop_device *lo, struct request *rq)
{
struct file *file = lo->lo_backing_file;
int ret = vfs_fsync(file, 0);
if (unlikely(ret && ret != -EINVAL))
ret = -EIO;
return ret;
}
static void lo_complete_rq(struct request *rq)
{
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
blk_status_t ret = BLK_STS_OK;
if (!cmd->use_aio || cmd->ret < 0 || cmd->ret == blk_rq_bytes(rq) ||
req_op(rq) != REQ_OP_READ) {
if (cmd->ret < 0)
ret = errno_to_blk_status(cmd->ret);
goto end_io;
}
/*
* Short READ - if we got some data, advance our request and
* retry it. If we got no data, end the rest with EIO.
*/
if (cmd->ret) {
blk_update_request(rq, BLK_STS_OK, cmd->ret);
cmd->ret = 0;
blk_mq_requeue_request(rq, true);
} else {
if (cmd->use_aio) {
struct bio *bio = rq->bio;
while (bio) {
zero_fill_bio(bio);
bio = bio->bi_next;
}
}
ret = BLK_STS_IOERR;
end_io:
blk_mq_end_request(rq, ret);
}
}
static void lo_rw_aio_do_completion(struct loop_cmd *cmd)
{
struct request *rq = blk_mq_rq_from_pdu(cmd);
if (!atomic_dec_and_test(&cmd->ref))
return;
kfree(cmd->bvec);
cmd->bvec = NULL;
if (likely(!blk_should_fake_timeout(rq->q)))
blk_mq_complete_request(rq);
}
static void lo_rw_aio_complete(struct kiocb *iocb, long ret, long ret2)
{
struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
if (cmd->css)
css_put(cmd->css);
cmd->ret = ret;
lo_rw_aio_do_completion(cmd);
}
static int lo_rw_aio(struct loop_device *lo, struct loop_cmd *cmd,
loff_t pos, bool rw)
{
struct iov_iter iter;
struct req_iterator rq_iter;
struct bio_vec *bvec;
struct request *rq = blk_mq_rq_from_pdu(cmd);
struct bio *bio = rq->bio;
struct file *file = lo->lo_backing_file;
struct bio_vec tmp;
unsigned int offset;
int nr_bvec = 0;
int ret;
rq_for_each_bvec(tmp, rq, rq_iter)
nr_bvec++;
if (rq->bio != rq->biotail) {
bvec = kmalloc_array(nr_bvec, sizeof(struct bio_vec),
GFP_NOIO);
if (!bvec)
return -EIO;
cmd->bvec = bvec;
/*
* The bios of the request may be started from the middle of
* the 'bvec' because of bio splitting, so we can't directly
* copy bio->bi_iov_vec to new bvec. The rq_for_each_bvec
* API will take care of all details for us.
*/
rq_for_each_bvec(tmp, rq, rq_iter) {
*bvec = tmp;
bvec++;
}
bvec = cmd->bvec;
offset = 0;
} else {
/*
* Same here, this bio may be started from the middle of the
* 'bvec' because of bio splitting, so offset from the bvec
* must be passed to iov iterator
*/
offset = bio->bi_iter.bi_bvec_done;
bvec = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
}
atomic_set(&cmd->ref, 2);
iov_iter_bvec(&iter, rw, bvec, nr_bvec, blk_rq_bytes(rq));
iter.iov_offset = offset;
cmd->iocb.ki_pos = pos;
cmd->iocb.ki_filp = file;
cmd->iocb.ki_complete = lo_rw_aio_complete;
cmd->iocb.ki_flags = IOCB_DIRECT;
cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
if (cmd->css)
kthread_associate_blkcg(cmd->css);
if (rw == WRITE)
ret = call_write_iter(file, &cmd->iocb, &iter);
else
ret = call_read_iter(file, &cmd->iocb, &iter);
lo_rw_aio_do_completion(cmd);
kthread_associate_blkcg(NULL);
if (ret != -EIOCBQUEUED)
cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
return 0;
}
static int do_req_filebacked(struct loop_device *lo, struct request *rq)
{
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
loff_t pos = ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
/*
* lo_write_simple and lo_read_simple should have been covered
* by io submit style function like lo_rw_aio(), one blocker
* is that lo_read_simple() need to call flush_dcache_page after
* the page is written from kernel, and it isn't easy to handle
* this in io submit style function which submits all segments
* of the req at one time. And direct read IO doesn't need to
* run flush_dcache_page().
*/
switch (req_op(rq)) {
case REQ_OP_FLUSH:
return lo_req_flush(lo, rq);
case REQ_OP_WRITE_ZEROES:
/*
* If the caller doesn't want deallocation, call zeroout to
* write zeroes the range. Otherwise, punch them out.
*/
return lo_fallocate(lo, rq, pos,
(rq->cmd_flags & REQ_NOUNMAP) ?
FALLOC_FL_ZERO_RANGE :
FALLOC_FL_PUNCH_HOLE);
case REQ_OP_DISCARD:
return lo_fallocate(lo, rq, pos, FALLOC_FL_PUNCH_HOLE);
case REQ_OP_WRITE:
if (lo->transfer)
return lo_write_transfer(lo, rq, pos);
else if (cmd->use_aio)
return lo_rw_aio(lo, cmd, pos, WRITE);
else
return lo_write_simple(lo, rq, pos);
case REQ_OP_READ:
if (lo->transfer)
return lo_read_transfer(lo, rq, pos);
else if (cmd->use_aio)
return lo_rw_aio(lo, cmd, pos, READ);
else
return lo_read_simple(lo, rq, pos);
default:
WARN_ON_ONCE(1);
return -EIO;
}
}
static inline void loop_update_dio(struct loop_device *lo)
{
__loop_update_dio(lo, (lo->lo_backing_file->f_flags & O_DIRECT) |
lo->use_dio);
}
static void loop_reread_partitions(struct loop_device *lo,
struct block_device *bdev)
{
int rc;
mutex_lock(&bdev->bd_mutex);
rc = bdev_disk_changed(bdev, false);
mutex_unlock(&bdev->bd_mutex);
if (rc)
pr_warn("%s: partition scan of loop%d (%s) failed (rc=%d)\n",
__func__, lo->lo_number, lo->lo_file_name, rc);
}
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;
}
static int loop_validate_file(struct file *file, struct block_device *bdev)
{
struct inode *inode = file->f_mapping->host;
struct file *f = file;
/* Avoid recursion */
while (is_loop_device(f)) {
struct loop_device *l;
if (f->f_mapping->host->i_rdev == bdev->bd_dev)
return -EBADF;
l = I_BDEV(f->f_mapping->host)->bd_disk->private_data;
if (l->lo_state != Lo_bound) {
return -EINVAL;
}
f = l->lo_backing_file;
}
if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
return -EINVAL;
return 0;
}
/*
* 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 = NULL, *old_file;
int error;
bool partscan;
error = mutex_lock_killable(&loop_ctl_mutex);
if (error)
return error;
error = -ENXIO;
if (lo->lo_state != Lo_bound)
goto out_err;
/* the loop device has to be read-only */
error = -EINVAL;
if (!(lo->lo_flags & LO_FLAGS_READ_ONLY))
goto out_err;
error = -EBADF;
file = fget(arg);
if (!file)
goto out_err;
error = loop_validate_file(file, bdev);
if (error)
goto out_err;
old_file = lo->lo_backing_file;
error = -EINVAL;
/* 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_err;
/* and ... switch */
blk_mq_freeze_queue(lo->lo_queue);
mapping_set_gfp_mask(old_file->f_mapping, lo->old_gfp_mask);
lo->lo_backing_file = file;
lo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
mapping_set_gfp_mask(file->f_mapping,
lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
loop_update_dio(lo);
blk_mq_unfreeze_queue(lo->lo_queue);
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
mutex_unlock(&loop_ctl_mutex);
/*
* We must drop file reference outside of loop_ctl_mutex as dropping
* the file ref can take bd_mutex which creates circular locking
* dependency.
*/
fput(old_file);
if (partscan)
loop_reread_partitions(lo, bdev);
return 0;
out_err:
mutex_unlock(&loop_ctl_mutex);
if (file)
fput(file);
return error;
}
/* 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, 0444, 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 = file_path(lo->lo_backing_file, 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");
}
static ssize_t loop_attr_dio_show(struct loop_device *lo, char *buf)
{
int dio = (lo->lo_flags & LO_FLAGS_DIRECT_IO);
return sprintf(buf, "%s\n", dio ? "1" : "0");
}
LOOP_ATTR_RO(backing_file);
LOOP_ATTR_RO(offset);
LOOP_ATTR_RO(sizelimit);
LOOP_ATTR_RO(autoclear);
LOOP_ATTR_RO(partscan);
LOOP_ATTR_RO(dio);
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,
&loop_attr_dio.attr,
NULL,
};
static struct attribute_group loop_attribute_group = {
.name = "loop",
.attrs= loop_attrs,
};
static void loop_sysfs_init(struct loop_device *lo)
{
lo->sysfs_inited = !sysfs_create_group(&disk_to_dev(lo->lo_disk)->kobj,
&loop_attribute_group);
}
static void loop_sysfs_exit(struct loop_device *lo)
{
if (lo->sysfs_inited)
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;
u32 granularity, max_discard_sectors;
/*
* If the backing device is a block device, mirror its zeroing
* capability. Set the discard sectors to the block device's zeroing
* capabilities because loop discards result in blkdev_issue_zeroout(),
* not blkdev_issue_discard(). This maintains consistent behavior with
* file-backed loop devices: discarded regions read back as zero.
*/
if (S_ISBLK(inode->i_mode) && !lo->lo_encrypt_key_size) {
struct request_queue *backingq = bdev_get_queue(I_BDEV(inode));
max_discard_sectors = backingq->limits.max_write_zeroes_sectors;
granularity = backingq->limits.discard_granularity ?:
queue_physical_block_size(backingq);
/*
* 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.
*/
} else if (!file->f_op->fallocate || lo->lo_encrypt_key_size) {
max_discard_sectors = 0;
granularity = 0;
} else {
max_discard_sectors = UINT_MAX >> 9;
granularity = inode->i_sb->s_blocksize;
}
if (max_discard_sectors) {
q->limits.discard_granularity = granularity;
blk_queue_max_discard_sectors(q, max_discard_sectors);
blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
} else {
q->limits.discard_granularity = 0;
blk_queue_max_discard_sectors(q, 0);
blk_queue_max_write_zeroes_sectors(q, 0);
blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
}
q->limits.discard_alignment = 0;
}
static void loop_unprepare_queue(struct loop_device *lo)
{
kthread_flush_worker(&lo->worker);
kthread_stop(lo->worker_task);
}
static int loop_kthread_worker_fn(void *worker_ptr)
{
current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
return kthread_worker_fn(worker_ptr);
}
static int loop_prepare_queue(struct loop_device *lo)
{
kthread_init_worker(&lo->worker);
lo->worker_task = kthread_run(loop_kthread_worker_fn,
&lo->worker, "loop%d", lo->lo_number);
if (IS_ERR(lo->worker_task))
return -ENOMEM;
set_user_nice(lo->worker_task, MIN_NICE);
return 0;
}
static void loop_update_rotational(struct loop_device *lo)
{
struct file *file = lo->lo_backing_file;
struct inode *file_inode = file->f_mapping->host;
struct block_device *file_bdev = file_inode->i_sb->s_bdev;
struct request_queue *q = lo->lo_queue;
bool nonrot = true;
/* not all filesystems (e.g. tmpfs) have a sb->s_bdev */
if (file_bdev)
nonrot = blk_queue_nonrot(bdev_get_queue(file_bdev));
if (nonrot)
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
else
blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
}
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;
}
/**
* loop_set_status_from_info - configure device from loop_info
* @lo: struct loop_device to configure
* @info: struct loop_info64 to configure the device with
*
* Configures the loop device parameters according to the passed
* in loop_info64 configuration.
*/
static int
loop_set_status_from_info(struct loop_device *lo,
const struct loop_info64 *info)
{
int err;
struct loop_func_table *xfer;
kuid_t uid = current_uid();
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;
lo->lo_offset = info->lo_offset;
lo->lo_sizelimit = info->lo_sizelimit;
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;
lo->lo_flags = info->lo_flags;
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_configure(struct loop_device *lo, fmode_t mode,
struct block_device *bdev,
const struct loop_config *config)
{
struct file *file;
struct inode *inode;
struct address_space *mapping;
int error;
loff_t size;
bool partscan;
unsigned short bsize;
/* This is safe, since we have a reference from open(). */
__module_get(THIS_MODULE);
error = -EBADF;
file = fget(config->fd);
if (!file)
goto out;
/*
* If we don't hold exclusive handle for the device, upgrade to it
* here to avoid changing device under exclusive owner.
*/
if (!(mode & FMODE_EXCL)) {
error = bd_prepare_to_claim(bdev, loop_configure);
if (error)
goto out_putf;
}
error = mutex_lock_killable(&loop_ctl_mutex);
if (error)
goto out_bdev;
error = -EBUSY;
if (lo->lo_state != Lo_unbound)
goto out_unlock;
error = loop_validate_file(file, bdev);
if (error)
goto out_unlock;
mapping = file->f_mapping;
inode = mapping->host;
if ((config->info.lo_flags & ~LOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
error = -EINVAL;
goto out_unlock;
}
if (config->block_size) {
error = loop_validate_block_size(config->block_size);
if (error)
goto out_unlock;
}
error = loop_set_status_from_info(lo, &config->info);
if (error)
goto out_unlock;
if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
!file->f_op->write_iter)
lo->lo_flags |= LO_FLAGS_READ_ONLY;
error = loop_prepare_queue(lo);
if (error)
goto out_unlock;
set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
lo->use_dio = lo->lo_flags & LO_FLAGS_DIRECT_IO;
lo->lo_device = bdev;
lo->lo_backing_file = file;
lo->old_gfp_mask = mapping_gfp_mask(mapping);
mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
if (!(lo->lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync)
blk_queue_write_cache(lo->lo_queue, true, false);
if (config->block_size)
bsize = config->block_size;
else if ((lo->lo_backing_file->f_flags & O_DIRECT) && inode->i_sb->s_bdev)
/* In case of direct I/O, match underlying block size */
bsize = bdev_logical_block_size(inode->i_sb->s_bdev);
else
bsize = 512;
blk_queue_logical_block_size(lo->lo_queue, bsize);
blk_queue_physical_block_size(lo->lo_queue, bsize);
blk_queue_io_min(lo->lo_queue, bsize);
loop_update_rotational(lo);
loop_update_dio(lo);
loop_sysfs_init(lo);
size = get_loop_size(lo, file);
loop_set_size(lo, size);
lo->lo_state = Lo_bound;
if (part_shift)
lo->lo_flags |= LO_FLAGS_PARTSCAN;
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN;
if (partscan)
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
/* Grab the block_device to prevent its destruction after we
* put /dev/loopXX inode. Later in __loop_clr_fd() we bdput(bdev).
*/
bdgrab(bdev);
mutex_unlock(&loop_ctl_mutex);
if (partscan)
loop_reread_partitions(lo, bdev);
if (!(mode & FMODE_EXCL))
bd_abort_claiming(bdev, loop_configure);
return 0;
out_unlock:
mutex_unlock(&loop_ctl_mutex);
out_bdev:
if (!(mode & FMODE_EXCL))
bd_abort_claiming(bdev, loop_configure);
out_putf:
fput(file);
out:
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
return error;
}
static int __loop_clr_fd(struct loop_device *lo, bool release)
{
struct file *filp = NULL;
gfp_t gfp = lo->old_gfp_mask;
struct block_device *bdev = lo->lo_device;
int err = 0;
bool partscan = false;
int lo_number;
mutex_lock(&loop_ctl_mutex);
if (WARN_ON_ONCE(lo->lo_state != Lo_rundown)) {
err = -ENXIO;
goto out_unlock;
}
filp = lo->lo_backing_file;
if (filp == NULL) {
err = -EINVAL;
goto out_unlock;
}
/* freeze request queue during the transition */
blk_mq_freeze_queue(lo->lo_queue);
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;
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);
blk_queue_logical_block_size(lo->lo_queue, 512);
blk_queue_physical_block_size(lo->lo_queue, 512);
blk_queue_io_min(lo->lo_queue, 512);
if (bdev) {
bdput(bdev);
invalidate_bdev(bdev);
bdev->bd_inode->i_mapping->wb_err = 0;
}
set_capacity(lo->lo_disk, 0);
loop_sysfs_exit(lo);
if (bdev) {
/* 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);
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
blk_mq_unfreeze_queue(lo->lo_queue);
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
lo_number = lo->lo_number;
loop_unprepare_queue(lo);
out_unlock:
mutex_unlock(&loop_ctl_mutex);
if (partscan) {
/*
* bd_mutex has been held already in release path, so don't
* acquire it if this function is called in such case.
*
* If the reread partition isn't from release path, lo_refcnt
* must be at least one and it can only become zero when the
* current holder is released.
*/
if (!release)
mutex_lock(&bdev->bd_mutex);
err = bdev_disk_changed(bdev, false);
if (!release)
mutex_unlock(&bdev->bd_mutex);
if (err)
pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
__func__, lo_number, err);
/* Device is gone, no point in returning error */
err = 0;
}
/*
* lo->lo_state is set to Lo_unbound here after above partscan has
* finished.
*
* There cannot be anybody else entering __loop_clr_fd() as
* lo->lo_backing_file is already cleared and Lo_rundown state
* protects us from all the other places trying to change the 'lo'
* device.
*/
mutex_lock(&loop_ctl_mutex);
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
lo->lo_state = Lo_unbound;
mutex_unlock(&loop_ctl_mutex);
/*
* Need not hold loop_ctl_mutex to fput backing file.
* Calling fput holding loop_ctl_mutex triggers a circular
* lock dependency possibility warning as fput can take
* bd_mutex which is usually taken before loop_ctl_mutex.
*/
if (filp)
fput(filp);
return err;
}
static int loop_clr_fd(struct loop_device *lo)
{
int err;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
return err;
if (lo->lo_state != Lo_bound) {
mutex_unlock(&loop_ctl_mutex);
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 (atomic_read(&lo->lo_refcnt) > 1) {
lo->lo_flags |= LO_FLAGS_AUTOCLEAR;
mutex_unlock(&loop_ctl_mutex);
return 0;
}
lo->lo_state = Lo_rundown;
mutex_unlock(&loop_ctl_mutex);
return __loop_clr_fd(lo, false);
}
static int
loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
{
int err;
struct block_device *bdev;
kuid_t uid = current_uid();
int prev_lo_flags;
bool partscan = false;
bool size_changed = false;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
return err;
if (lo->lo_encrypt_key_size &&
!uid_eq(lo->lo_key_owner, uid) &&
!capable(CAP_SYS_ADMIN)) {
err = -EPERM;
goto out_unlock;
}
if (lo->lo_state != Lo_bound) {
err = -ENXIO;
goto out_unlock;
}
if (lo->lo_offset != info->lo_offset ||
lo->lo_sizelimit != info->lo_sizelimit) {
size_changed = true;
sync_blockdev(lo->lo_device);
invalidate_bdev(lo->lo_device);
}
/* I/O need to be drained during transfer transition */
blk_mq_freeze_queue(lo->lo_queue);
if (size_changed && lo->lo_device->bd_inode->i_mapping->nrpages) {
/* If any pages were dirtied after invalidate_bdev(), try again */
err = -EAGAIN;
pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
__func__, lo->lo_number, lo->lo_file_name,
lo->lo_device->bd_inode->i_mapping->nrpages);
goto out_unfreeze;
}
prev_lo_flags = lo->lo_flags;
err = loop_set_status_from_info(lo, info);
if (err)
goto out_unfreeze;
/* Mask out flags that can't be set using LOOP_SET_STATUS. */
lo->lo_flags &= LOOP_SET_STATUS_SETTABLE_FLAGS;
/* For those flags, use the previous values instead */
lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_SETTABLE_FLAGS;
/* For flags that can't be cleared, use previous values too */
lo->lo_flags |= prev_lo_flags & ~LOOP_SET_STATUS_CLEARABLE_FLAGS;
if (size_changed) {
loff_t new_size = get_size(lo->lo_offset, lo->lo_sizelimit,
lo->lo_backing_file);
loop_set_size(lo, new_size);
}
loop_config_discard(lo);
/* update dio if lo_offset or transfer is changed */
__loop_update_dio(lo, lo->use_dio);
out_unfreeze:
blk_mq_unfreeze_queue(lo->lo_queue);
if (!err && (lo->lo_flags & LO_FLAGS_PARTSCAN) &&
!(prev_lo_flags & LO_FLAGS_PARTSCAN)) {
lo->lo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
bdev = lo->lo_device;
partscan = true;
}
out_unlock:
mutex_unlock(&loop_ctl_mutex);
if (partscan)
loop_reread_partitions(lo, bdev);
return err;
}
static int
loop_get_status(struct loop_device *lo, struct loop_info64 *info)
{
struct path path;
struct kstat stat;
int ret;
ret = mutex_lock_killable(&loop_ctl_mutex);
if (ret)
return ret;
if (lo->lo_state != Lo_bound) {
mutex_unlock(&loop_ctl_mutex);
return -ENXIO;
}
memset(info, 0, sizeof(*info));
info->lo_number = lo->lo_number;
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);
}
/* Drop loop_ctl_mutex while we call into the filesystem. */
path = lo->lo_backing_file->f_path;
path_get(&path);
mutex_unlock(&loop_ctl_mutex);
ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
if (!ret) {
info->lo_device = huge_encode_dev(stat.dev);
info->lo_inode = stat.ino;
info->lo_rdevice = huge_encode_dev(stat.rdev);
}
path_put(&path);
return ret;
}
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;
if (!arg)
return -EINVAL;
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;
if (!arg)
return -EINVAL;
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)
{
loff_t size;
if (unlikely(lo->lo_state != Lo_bound))
return -ENXIO;
size = get_loop_size(lo, lo->lo_backing_file);
loop_set_size(lo, size);
return 0;
}
static int loop_set_dio(struct loop_device *lo, unsigned long arg)
{
int error = -ENXIO;
if (lo->lo_state != Lo_bound)
goto out;
__loop_update_dio(lo, !!arg);
if (lo->use_dio == !!arg)
return 0;
error = -EINVAL;
out:
return error;
}
static int loop_set_block_size(struct loop_device *lo, unsigned long arg)
{
int err = 0;
if (lo->lo_state != Lo_bound)
return -ENXIO;
err = loop_validate_block_size(arg);
if (err)
return err;
if (lo->lo_queue->limits.logical_block_size == arg)
return 0;
sync_blockdev(lo->lo_device);
invalidate_bdev(lo->lo_device);
blk_mq_freeze_queue(lo->lo_queue);
/* invalidate_bdev should have truncated all the pages */
if (lo->lo_device->bd_inode->i_mapping->nrpages) {
err = -EAGAIN;
pr_warn("%s: loop%d (%s) has still dirty pages (nrpages=%lu)\n",
__func__, lo->lo_number, lo->lo_file_name,
lo->lo_device->bd_inode->i_mapping->nrpages);
goto out_unfreeze;
}
blk_queue_logical_block_size(lo->lo_queue, arg);
blk_queue_physical_block_size(lo->lo_queue, arg);
blk_queue_io_min(lo->lo_queue, arg);
loop_update_dio(lo);
out_unfreeze:
blk_mq_unfreeze_queue(lo->lo_queue);
return err;
}
static int lo_simple_ioctl(struct loop_device *lo, unsigned int cmd,
unsigned long arg)
{
int err;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
return err;
switch (cmd) {
case LOOP_SET_CAPACITY:
err = loop_set_capacity(lo);
break;
case LOOP_SET_DIRECT_IO:
err = loop_set_dio(lo, arg);
break;
case LOOP_SET_BLOCK_SIZE:
err = loop_set_block_size(lo, arg);
break;
default:
err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;
}
mutex_unlock(&loop_ctl_mutex);
return err;
}
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;
void __user *argp = (void __user *) arg;
int err;
switch (cmd) {
case LOOP_SET_FD: {
/*
* Legacy case - pass in a zeroed out struct loop_config with
* only the file descriptor set , which corresponds with the
* default parameters we'd have used otherwise.
*/
struct loop_config config;
memset(&config, 0, sizeof(config));
config.fd = arg;
return loop_configure(lo, mode, bdev, &config);
}
case LOOP_CONFIGURE: {
struct loop_config config;
if (copy_from_user(&config, argp, sizeof(config)))
return -EFAULT;
return loop_configure(lo, mode, bdev, &config);
}
case LOOP_CHANGE_FD:
return loop_change_fd(lo, bdev, arg);
case LOOP_CLR_FD:
return loop_clr_fd(lo);
case LOOP_SET_STATUS:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
err = loop_set_status_old(lo, argp);
}
break;
case LOOP_GET_STATUS:
return loop_get_status_old(lo, argp);
case LOOP_SET_STATUS64:
err = -EPERM;
if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN)) {
err = loop_set_status64(lo, argp);
}
break;
case LOOP_GET_STATUS64:
return loop_get_status64(lo, argp);
case LOOP_SET_CAPACITY:
case LOOP_SET_DIRECT_IO:
case LOOP_SET_BLOCK_SIZE:
if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
return -EPERM;
fallthrough;
default:
err = lo_simple_ioctl(lo, cmd, arg);
break;
}
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;
if (!arg)
return -EINVAL;
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:
err = loop_set_status_compat(lo,
(const struct compat_loop_info __user *)arg);
break;
case LOOP_GET_STATUS:
err = loop_get_status_compat(lo,
(struct compat_loop_info __user *)arg);
break;
case LOOP_SET_CAPACITY:
case LOOP_CLR_FD:
case LOOP_GET_STATUS64:
case LOOP_SET_STATUS64:
case LOOP_CONFIGURE:
arg = (unsigned long) compat_ptr(arg);
fallthrough;
case LOOP_SET_FD:
case LOOP_CHANGE_FD:
case LOOP_SET_BLOCK_SIZE:
case LOOP_SET_DIRECT_IO:
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;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
return err;
lo = bdev->bd_disk->private_data;
if (!lo) {
err = -ENXIO;
goto out;
}
atomic_inc(&lo->lo_refcnt);
out:
mutex_unlock(&loop_ctl_mutex);
return err;
}
static void lo_release(struct gendisk *disk, fmode_t mode)
{
struct loop_device *lo;
mutex_lock(&loop_ctl_mutex);
lo = disk->private_data;
if (atomic_dec_return(&lo->lo_refcnt))
goto out_unlock;
if (lo->lo_flags & LO_FLAGS_AUTOCLEAR) {
if (lo->lo_state != Lo_bound)
goto out_unlock;
lo->lo_state = Lo_rundown;
mutex_unlock(&loop_ctl_mutex);
/*
* In autoclear mode, stop the loop thread
* and remove configuration after last close.
*/
__loop_clr_fd(lo, true);
return;
} else if (lo->lo_state == Lo_bound) {
/*
* Otherwise keep thread (if running) and config,
* but flush possible ongoing bios in thread.
*/
blk_mq_freeze_queue(lo->lo_queue);
blk_mq_unfreeze_queue(lo->lo_queue);
}
out_unlock:
mutex_unlock(&loop_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, 0444);
MODULE_PARM_DESC(max_loop, "Maximum number of loop devices");
module_param(max_part, int, 0444);
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(&loop_ctl_mutex);
if (lo->lo_encryption == xfer)
loop_release_xfer(lo);
mutex_unlock(&loop_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 blk_status_t loop_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct request *rq = bd->rq;
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
struct loop_device *lo = rq->q->queuedata;
blk_mq_start_request(rq);
if (lo->lo_state != Lo_bound)
return BLK_STS_IOERR;
switch (req_op(rq)) {
case REQ_OP_FLUSH:
case REQ_OP_DISCARD:
case REQ_OP_WRITE_ZEROES:
cmd->use_aio = false;
break;
default:
cmd->use_aio = lo->use_dio;
break;
}
/* always use the first bio's css */
#ifdef CONFIG_BLK_CGROUP
if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) {
cmd->css = &bio_blkcg(rq->bio)->css;
css_get(cmd->css);
} else
#endif
cmd->css = NULL;
kthread_queue_work(&lo->worker, &cmd->work);
return BLK_STS_OK;
}
static void loop_handle_cmd(struct loop_cmd *cmd)
{
struct request *rq = blk_mq_rq_from_pdu(cmd);
const bool write = op_is_write(req_op(rq));
struct loop_device *lo = rq->q->queuedata;
int ret = 0;
if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
ret = -EIO;
goto failed;
}
ret = do_req_filebacked(lo, rq);
failed:
/* complete non-aio request */
if (!cmd->use_aio || ret) {
if (ret == -EOPNOTSUPP)
cmd->ret = ret;
else
cmd->ret = ret ? -EIO : 0;
if (likely(!blk_should_fake_timeout(rq->q)))
blk_mq_complete_request(rq);
}
}
static void loop_queue_work(struct kthread_work *work)
{
struct loop_cmd *cmd =
container_of(work, struct loop_cmd, work);
loop_handle_cmd(cmd);
}
static int loop_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, unsigned int numa_node)
{
struct loop_cmd *cmd = blk_mq_rq_to_pdu(rq);
kthread_init_work(&cmd->work, loop_queue_work);
return 0;
}
static const struct blk_mq_ops loop_mq_ops = {
.queue_rq = loop_queue_rq,
.init_request = loop_init_request,
.complete = lo_complete_rq,
};
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->tag_set.ops = &loop_mq_ops;
lo->tag_set.nr_hw_queues = 1;
lo->tag_set.queue_depth = 128;
lo->tag_set.numa_node = NUMA_NO_NODE;
lo->tag_set.cmd_size = sizeof(struct loop_cmd);
lo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
lo->tag_set.driver_data = lo;
err = blk_mq_alloc_tag_set(&lo->tag_set);
if (err)
goto out_free_idr;
lo->lo_queue = blk_mq_init_queue(&lo->tag_set);
if (IS_ERR(lo->lo_queue)) {
err = PTR_ERR(lo->lo_queue);
goto out_cleanup_tags;
}
lo->lo_queue->queuedata = lo;
blk_queue_max_hw_sectors(lo->lo_queue, BLK_DEF_MAX_SECTORS);
/*
* By default, we do buffer IO, so it doesn't make sense to enable
* merge because the I/O submitted to backing file is handled page by
* page. For directio mode, merge does help to dispatch bigger request
* to underlayer disk. We will enable merge once directio is enabled.
*/
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, lo->lo_queue);
err = -ENOMEM;
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;
atomic_set(&lo->lo_refcnt, 0);
lo->lo_number = i;
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_cleanup_tags:
blk_mq_free_tag_set(&lo->tag_set);
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);
blk_mq_free_tag_set(&lo->tag_set);
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 void loop_probe(dev_t dev)
{
int idx = MINOR(dev) >> part_shift;
struct loop_device *lo;
if (max_loop && idx >= max_loop)
return;
mutex_lock(&loop_ctl_mutex);
if (loop_lookup(&lo, idx) < 0)
loop_add(&lo, idx);
mutex_unlock(&loop_ctl_mutex);
}
static long loop_control_ioctl(struct file *file, unsigned int cmd,
unsigned long parm)
{
struct loop_device *lo;
int ret;
ret = mutex_lock_killable(&loop_ctl_mutex);
if (ret)
return ret;
ret = -ENOSYS;
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;
if (lo->lo_state != Lo_unbound) {
ret = -EBUSY;
break;
}
if (atomic_read(&lo->lo_refcnt) > 0) {
ret = -EBUSY;
break;
}
lo->lo_disk->private_data = NULL;
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_ctl_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;
struct loop_device *lo;
int 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 err_out;
}
if (max_loop > 1UL << (MINORBITS - part_shift)) {
err = -EINVAL;
goto err_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;
else
nr = CONFIG_BLK_DEV_LOOP_MIN_COUNT;
err = misc_register(&loop_misc);
if (err < 0)
goto err_out;
if (__register_blkdev(LOOP_MAJOR, "loop", loop_probe)) {
err = -EIO;
goto misc_out;
}
/* pre-create number of devices given by config or max_loop */
mutex_lock(&loop_ctl_mutex);
for (i = 0; i < nr; i++)
loop_add(&lo, i);
mutex_unlock(&loop_ctl_mutex);
printk(KERN_INFO "loop: module loaded\n");
return 0;
misc_out:
misc_deregister(&loop_misc);
err_out:
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)
{
mutex_lock(&loop_ctl_mutex);
idr_for_each(&loop_index_idr, &loop_exit_cb, NULL);
idr_destroy(&loop_index_idr);
unregister_blkdev(LOOP_MAJOR, "loop");
misc_deregister(&loop_misc);
mutex_unlock(&loop_ctl_mutex);
}
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
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