linux/drivers/block/loop.c
Chaitanya Kulkarni ef44c50837 loop: allow user to set the queue depth
Instead of hardcoding queue depth allow user to set the hw queue depth
using module parameter. Set default value to 128 to retain the existing
behavior.

Signed-off-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Link: https://lore.kernel.org/r/20220215213310.7264-5-kch@nvidia.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-02-27 14:49:49 -07:00

2310 lines
58 KiB
C

/*
* 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/pagemap.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/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 <linux/sched/mm.h>
#include "loop.h"
#include <linux/uaccess.h>
#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
#define LOOP_DEFAULT_HW_Q_DEPTH (128)
static DEFINE_IDR(loop_index_idr);
static DEFINE_MUTEX(loop_ctl_mutex);
static DEFINE_MUTEX(loop_validate_mutex);
/**
* loop_global_lock_killable() - take locks for safe loop_validate_file() test
*
* @lo: struct loop_device
* @global: true if @lo is about to bind another "struct loop_device", false otherwise
*
* Returns 0 on success, -EINTR otherwise.
*
* Since loop_validate_file() traverses on other "struct loop_device" if
* is_loop_device() is true, we need a global lock for serializing concurrent
* loop_configure()/loop_change_fd()/__loop_clr_fd() calls.
*/
static int loop_global_lock_killable(struct loop_device *lo, bool global)
{
int err;
if (global) {
err = mutex_lock_killable(&loop_validate_mutex);
if (err)
return err;
}
err = mutex_lock_killable(&lo->lo_mutex);
if (err && global)
mutex_unlock(&loop_validate_mutex);
return err;
}
/**
* loop_global_unlock() - release locks taken by loop_global_lock_killable()
*
* @lo: struct loop_device
* @global: true if @lo was about to bind another "struct loop_device", false otherwise
*/
static void loop_global_unlock(struct loop_device *lo, bool global)
{
mutex_unlock(&lo->lo_mutex);
if (global)
mutex_unlock(&loop_validate_mutex);
}
static int max_part;
static int part_shift;
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.
*
* 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)
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_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 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;
}
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_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.
*/
struct file *file = lo->lo_backing_file;
int ret;
mode |= FALLOC_FL_KEEP_SIZE;
if (!blk_queue_discard(lo->lo_queue)) {
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)
{
int ret = vfs_fsync(lo->lo_backing_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)
{
struct loop_cmd *cmd = container_of(iocb, struct loop_cmd, iocb);
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 (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);
if (ret != -EIOCBQUEUED)
lo_rw_aio_complete(&cmd->iocb, ret);
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 (cmd->use_aio)
return lo_rw_aio(lo, cmd, pos, WRITE);
else
return lo_write_simple(lo, rq, pos);
case REQ_OP_READ:
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)
{
int rc;
mutex_lock(&lo->lo_disk->open_mutex);
rc = bdev_disk_changed(lo->lo_disk, false);
mutex_unlock(&lo->lo_disk->open_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) && imajor(i) == 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;
lockdep_assert_held(&loop_validate_mutex);
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;
/* Order wrt setting lo->lo_backing_file in loop_configure(). */
rmb();
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 = fget(arg);
struct file *old_file;
int error;
bool partscan;
bool is_loop;
if (!file)
return -EBADF;
is_loop = is_loop_device(file);
error = loop_global_lock_killable(lo, is_loop);
if (error)
goto out_putf;
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 = 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 */
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
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;
loop_global_unlock(lo, is_loop);
/*
* Flush loop_validate_file() before fput(), for l->lo_backing_file
* might be pointing at old_file which might be the last reference.
*/
if (!is_loop) {
mutex_lock(&loop_validate_mutex);
mutex_unlock(&loop_validate_mutex);
}
/*
* We must drop file reference outside of lo_mutex as dropping
* the file ref can take open_mutex which creates circular locking
* dependency.
*/
fput(old_file);
if (partscan)
loop_reread_partitions(lo);
return 0;
out_err:
loop_global_unlock(lo, is_loop);
out_putf:
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 sysfs_emit(buf, "%llu\n", (unsigned long long)lo->lo_offset);
}
static ssize_t loop_attr_sizelimit_show(struct loop_device *lo, char *buf)
{
return sysfs_emit(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 sysfs_emit(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 sysfs_emit(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 sysfs_emit(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)) {
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.
*/
} else if (!file->f_op->fallocate) {
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;
}
struct loop_worker {
struct rb_node rb_node;
struct work_struct work;
struct list_head cmd_list;
struct list_head idle_list;
struct loop_device *lo;
struct cgroup_subsys_state *blkcg_css;
unsigned long last_ran_at;
};
static void loop_workfn(struct work_struct *work);
static void loop_rootcg_workfn(struct work_struct *work);
static void loop_free_idle_workers(struct timer_list *timer);
#ifdef CONFIG_BLK_CGROUP
static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
{
return !css || css == blkcg_root_css;
}
#else
static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
{
return !css;
}
#endif
static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd)
{
struct rb_node **node, *parent = NULL;
struct loop_worker *cur_worker, *worker = NULL;
struct work_struct *work;
struct list_head *cmd_list;
spin_lock_irq(&lo->lo_work_lock);
if (queue_on_root_worker(cmd->blkcg_css))
goto queue_work;
node = &lo->worker_tree.rb_node;
while (*node) {
parent = *node;
cur_worker = container_of(*node, struct loop_worker, rb_node);
if (cur_worker->blkcg_css == cmd->blkcg_css) {
worker = cur_worker;
break;
} else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) {
node = &(*node)->rb_left;
} else {
node = &(*node)->rb_right;
}
}
if (worker)
goto queue_work;
worker = kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN);
/*
* In the event we cannot allocate a worker, just queue on the
* rootcg worker and issue the I/O as the rootcg
*/
if (!worker) {
cmd->blkcg_css = NULL;
if (cmd->memcg_css)
css_put(cmd->memcg_css);
cmd->memcg_css = NULL;
goto queue_work;
}
worker->blkcg_css = cmd->blkcg_css;
css_get(worker->blkcg_css);
INIT_WORK(&worker->work, loop_workfn);
INIT_LIST_HEAD(&worker->cmd_list);
INIT_LIST_HEAD(&worker->idle_list);
worker->lo = lo;
rb_link_node(&worker->rb_node, parent, node);
rb_insert_color(&worker->rb_node, &lo->worker_tree);
queue_work:
if (worker) {
/*
* We need to remove from the idle list here while
* holding the lock so that the idle timer doesn't
* free the worker
*/
if (!list_empty(&worker->idle_list))
list_del_init(&worker->idle_list);
work = &worker->work;
cmd_list = &worker->cmd_list;
} else {
work = &lo->rootcg_work;
cmd_list = &lo->rootcg_cmd_list;
}
list_add_tail(&cmd->list_entry, cmd_list);
queue_work(lo->workqueue, work);
spin_unlock_irq(&lo->lo_work_lock);
}
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);
}
/**
* 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)
{
if ((unsigned int) info->lo_encrypt_key_size > LO_KEY_SIZE)
return -EINVAL;
switch (info->lo_encrypt_type) {
case LO_CRYPT_NONE:
break;
case LO_CRYPT_XOR:
pr_warn("support for the xor transformation has been removed.\n");
return -EINVAL;
case LO_CRYPT_CRYPTOAPI:
pr_warn("support for cryptoloop has been removed. Use dm-crypt instead.\n");
return -EINVAL;
default:
return -EINVAL;
}
lo->lo_offset = info->lo_offset;
lo->lo_sizelimit = info->lo_sizelimit;
memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE);
lo->lo_file_name[LO_NAME_SIZE-1] = 0;
lo->lo_flags = info->lo_flags;
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 = fget(config->fd);
struct inode *inode;
struct address_space *mapping;
int error;
loff_t size;
bool partscan;
unsigned short bsize;
bool is_loop;
if (!file)
return -EBADF;
is_loop = is_loop_device(file);
/* This is safe, since we have a reference from open(). */
__module_get(THIS_MODULE);
/*
* 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 = loop_global_lock_killable(lo, is_loop);
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 = blk_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;
lo->workqueue = alloc_workqueue("loop%d",
WQ_UNBOUND | WQ_FREEZABLE,
0,
lo->lo_number);
if (!lo->workqueue) {
error = -ENOMEM;
goto out_unlock;
}
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn);
INIT_LIST_HEAD(&lo->rootcg_cmd_list);
INIT_LIST_HEAD(&lo->idle_worker_list);
lo->worker_tree = RB_ROOT;
timer_setup(&lo->timer, loop_free_idle_workers,
TIMER_DEFERRABLE);
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_config_discard(lo);
loop_update_rotational(lo);
loop_update_dio(lo);
loop_sysfs_init(lo);
size = get_loop_size(lo, file);
loop_set_size(lo, size);
/* Order wrt reading lo_state in loop_validate_file(). */
wmb();
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;
loop_global_unlock(lo, is_loop);
if (partscan)
loop_reread_partitions(lo);
if (!(mode & FMODE_EXCL))
bd_abort_claiming(bdev, loop_configure);
return 0;
out_unlock:
loop_global_unlock(lo, is_loop);
out_bdev:
if (!(mode & FMODE_EXCL))
bd_abort_claiming(bdev, loop_configure);
out_putf:
fput(file);
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
return error;
}
static void __loop_clr_fd(struct loop_device *lo)
{
struct file *filp;
gfp_t gfp = lo->old_gfp_mask;
struct loop_worker *pos, *worker;
/*
* Flush loop_configure() and loop_change_fd(). It is acceptable for
* loop_validate_file() to succeed, for actual clear operation has not
* started yet.
*/
mutex_lock(&loop_validate_mutex);
mutex_unlock(&loop_validate_mutex);
/*
* loop_validate_file() now fails because l->lo_state != Lo_bound
* became visible.
*/
/*
* Since this function is called upon "ioctl(LOOP_CLR_FD)" xor "close()
* after ioctl(LOOP_CLR_FD)", it is a sign of something going wrong if
* lo->lo_state has changed while waiting for lo->lo_mutex.
*/
mutex_lock(&lo->lo_mutex);
BUG_ON(lo->lo_state != Lo_rundown);
mutex_unlock(&lo->lo_mutex);
if (test_bit(QUEUE_FLAG_WC, &lo->lo_queue->queue_flags))
blk_queue_write_cache(lo->lo_queue, false, false);
/* freeze request queue during the transition */
blk_mq_freeze_queue(lo->lo_queue);
destroy_workqueue(lo->workqueue);
spin_lock_irq(&lo->lo_work_lock);
list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
idle_list) {
list_del(&worker->idle_list);
rb_erase(&worker->rb_node, &lo->worker_tree);
css_put(worker->blkcg_css);
kfree(worker);
}
spin_unlock_irq(&lo->lo_work_lock);
del_timer_sync(&lo->timer);
spin_lock_irq(&lo->lo_lock);
filp = lo->lo_backing_file;
lo->lo_backing_file = NULL;
spin_unlock_irq(&lo->lo_lock);
lo->lo_device = NULL;
lo->lo_offset = 0;
lo->lo_sizelimit = 0;
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);
invalidate_disk(lo->lo_disk);
loop_sysfs_exit(lo);
/* let user-space know about this change */
kobject_uevent(&disk_to_dev(lo->lo_disk)->kobj, KOBJ_CHANGE);
mapping_set_gfp_mask(filp->f_mapping, gfp);
blk_mq_unfreeze_queue(lo->lo_queue);
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
if (lo->lo_flags & LO_FLAGS_PARTSCAN) {
int err;
mutex_lock(&lo->lo_disk->open_mutex);
err = bdev_disk_changed(lo->lo_disk, false);
mutex_unlock(&lo->lo_disk->open_mutex);
if (err)
pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
__func__, lo->lo_number, err);
/* Device is gone, no point in returning error */
}
lo->lo_flags = 0;
if (!part_shift)
lo->lo_disk->flags |= GENHD_FL_NO_PART;
fput(filp);
}
static void loop_rundown_completed(struct loop_device *lo)
{
mutex_lock(&lo->lo_mutex);
lo->lo_state = Lo_unbound;
mutex_unlock(&lo->lo_mutex);
module_put(THIS_MODULE);
}
static void loop_rundown_workfn(struct work_struct *work)
{
struct loop_device *lo = container_of(work, struct loop_device,
rundown_work);
struct block_device *bdev = lo->lo_device;
struct gendisk *disk = lo->lo_disk;
__loop_clr_fd(lo);
kobject_put(&bdev->bd_device.kobj);
module_put(disk->fops->owner);
loop_rundown_completed(lo);
}
static void loop_schedule_rundown(struct loop_device *lo)
{
struct block_device *bdev = lo->lo_device;
struct gendisk *disk = lo->lo_disk;
__module_get(disk->fops->owner);
kobject_get(&bdev->bd_device.kobj);
INIT_WORK(&lo->rundown_work, loop_rundown_workfn);
queue_work(system_long_wq, &lo->rundown_work);
}
static int loop_clr_fd(struct loop_device *lo)
{
int err;
err = mutex_lock_killable(&lo->lo_mutex);
if (err)
return err;
if (lo->lo_state != Lo_bound) {
mutex_unlock(&lo->lo_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(&lo->lo_mutex);
return 0;
}
lo->lo_state = Lo_rundown;
mutex_unlock(&lo->lo_mutex);
__loop_clr_fd(lo);
loop_rundown_completed(lo);
return 0;
}
static int
loop_set_status(struct loop_device *lo, const struct loop_info64 *info)
{
int err;
int prev_lo_flags;
bool partscan = false;
bool size_changed = false;
err = mutex_lock_killable(&lo->lo_mutex);
if (err)
return err;
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) still has 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;
partscan = true;
}
out_unlock:
mutex_unlock(&lo->lo_mutex);
if (partscan)
loop_reread_partitions(lo);
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(&lo->lo_mutex);
if (ret)
return ret;
if (lo->lo_state != Lo_bound) {
mutex_unlock(&lo->lo_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);
/* Drop lo_mutex while we call into the filesystem. */
path = lo->lo_backing_file->f_path;
path_get(&path);
mutex_unlock(&lo->lo_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_flags = info->lo_flags;
memcpy(info64->lo_file_name, info->lo_name, LO_NAME_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_flags = info64->lo_flags;
memcpy(info->lo_name, info64->lo_file_name, LO_NAME_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 = blk_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) still has 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(&lo->lo_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 = -EINVAL;
}
mutex_unlock(&lo->lo_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_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_flags = info.lo_flags;
memcpy(info64->lo_file_name, info.lo_name, LO_NAME_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_flags = info64->lo_flags;
memcpy(info.lo_name, info64->lo_file_name, LO_NAME_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;
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 = bdev->bd_disk->private_data;
int err;
err = mutex_lock_killable(&lo->lo_mutex);
if (err)
return err;
if (lo->lo_state == Lo_deleting)
err = -ENXIO;
else
atomic_inc(&lo->lo_refcnt);
mutex_unlock(&lo->lo_mutex);
return err;
}
static void lo_release(struct gendisk *disk, fmode_t mode)
{
struct loop_device *lo = disk->private_data;
mutex_lock(&lo->lo_mutex);
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(&lo->lo_mutex);
/*
* In autoclear mode, stop the loop thread
* and remove configuration after last close.
*/
loop_schedule_rundown(lo);
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(&lo->lo_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");
static int hw_queue_depth = LOOP_DEFAULT_HW_Q_DEPTH;
static int loop_set_hw_queue_depth(const char *s, const struct kernel_param *p)
{
int ret = kstrtoint(s, 10, &hw_queue_depth);
return (ret || (hw_queue_depth < 1)) ? -EINVAL : 0;
}
static const struct kernel_param_ops loop_hw_qdepth_param_ops = {
.set = loop_set_hw_queue_depth,
.get = param_get_int,
};
device_param_cb(hw_queue_depth, &loop_hw_qdepth_param_ops, &hw_queue_depth, 0444);
MODULE_PARM_DESC(hw_queue_depth, "Queue depth for each hardware queue. Default: 128");
MODULE_LICENSE("GPL");
MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR);
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 */
cmd->blkcg_css = NULL;
cmd->memcg_css = NULL;
#ifdef CONFIG_BLK_CGROUP
if (rq->bio && rq->bio->bi_blkg) {
cmd->blkcg_css = &bio_blkcg(rq->bio)->css;
#ifdef CONFIG_MEMCG
cmd->memcg_css =
cgroup_get_e_css(cmd->blkcg_css->cgroup,
&memory_cgrp_subsys);
#endif
}
#endif
loop_queue_work(lo, cmd);
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;
struct mem_cgroup *old_memcg = NULL;
if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) {
ret = -EIO;
goto failed;
}
if (cmd->blkcg_css)
kthread_associate_blkcg(cmd->blkcg_css);
if (cmd->memcg_css)
old_memcg = set_active_memcg(
mem_cgroup_from_css(cmd->memcg_css));
ret = do_req_filebacked(lo, rq);
if (cmd->blkcg_css)
kthread_associate_blkcg(NULL);
if (cmd->memcg_css) {
set_active_memcg(old_memcg);
css_put(cmd->memcg_css);
}
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_set_timer(struct loop_device *lo)
{
timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT);
}
static void loop_process_work(struct loop_worker *worker,
struct list_head *cmd_list, struct loop_device *lo)
{
int orig_flags = current->flags;
struct loop_cmd *cmd;
current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
spin_lock_irq(&lo->lo_work_lock);
while (!list_empty(cmd_list)) {
cmd = container_of(
cmd_list->next, struct loop_cmd, list_entry);
list_del(cmd_list->next);
spin_unlock_irq(&lo->lo_work_lock);
loop_handle_cmd(cmd);
cond_resched();
spin_lock_irq(&lo->lo_work_lock);
}
/*
* We only add to the idle list if there are no pending cmds
* *and* the worker will not run again which ensures that it
* is safe to free any worker on the idle list
*/
if (worker && !work_pending(&worker->work)) {
worker->last_ran_at = jiffies;
list_add_tail(&worker->idle_list, &lo->idle_worker_list);
loop_set_timer(lo);
}
spin_unlock_irq(&lo->lo_work_lock);
current->flags = orig_flags;
}
static void loop_workfn(struct work_struct *work)
{
struct loop_worker *worker =
container_of(work, struct loop_worker, work);
loop_process_work(worker, &worker->cmd_list, worker->lo);
}
static void loop_rootcg_workfn(struct work_struct *work)
{
struct loop_device *lo =
container_of(work, struct loop_device, rootcg_work);
loop_process_work(NULL, &lo->rootcg_cmd_list, lo);
}
static void loop_free_idle_workers(struct timer_list *timer)
{
struct loop_device *lo = container_of(timer, struct loop_device, timer);
struct loop_worker *pos, *worker;
spin_lock_irq(&lo->lo_work_lock);
list_for_each_entry_safe(worker, pos, &lo->idle_worker_list,
idle_list) {
if (time_is_after_jiffies(worker->last_ran_at +
LOOP_IDLE_WORKER_TIMEOUT))
break;
list_del(&worker->idle_list);
rb_erase(&worker->rb_node, &lo->worker_tree);
css_put(worker->blkcg_css);
kfree(worker);
}
if (!list_empty(&lo->idle_worker_list))
loop_set_timer(lo);
spin_unlock_irq(&lo->lo_work_lock);
}
static const struct blk_mq_ops loop_mq_ops = {
.queue_rq = loop_queue_rq,
.complete = lo_complete_rq,
};
static int loop_add(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;
err = mutex_lock_killable(&loop_ctl_mutex);
if (err)
goto out_free_dev;
/* 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);
}
mutex_unlock(&loop_ctl_mutex);
if (err < 0)
goto out_free_dev;
i = err;
lo->tag_set.ops = &loop_mq_ops;
lo->tag_set.nr_hw_queues = 1;
lo->tag_set.queue_depth = hw_queue_depth;
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 |
BLK_MQ_F_NO_SCHED_BY_DEFAULT;
lo->tag_set.driver_data = lo;
err = blk_mq_alloc_tag_set(&lo->tag_set);
if (err)
goto out_free_idr;
disk = lo->lo_disk = blk_mq_alloc_disk(&lo->tag_set, lo);
if (IS_ERR(disk)) {
err = PTR_ERR(disk);
goto out_cleanup_tags;
}
lo->lo_queue = lo->lo_disk->queue;
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);
/*
* 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;
atomic_set(&lo->lo_refcnt, 0);
mutex_init(&lo->lo_mutex);
lo->lo_number = i;
spin_lock_init(&lo->lo_lock);
spin_lock_init(&lo->lo_work_lock);
disk->major = LOOP_MAJOR;
disk->first_minor = i << part_shift;
disk->minors = 1 << part_shift;
disk->fops = &lo_fops;
disk->private_data = lo;
disk->queue = lo->lo_queue;
disk->events = DISK_EVENT_MEDIA_CHANGE;
disk->event_flags = DISK_EVENT_FLAG_UEVENT;
sprintf(disk->disk_name, "loop%d", i);
/* Make this loop device reachable from pathname. */
err = add_disk(disk);
if (err)
goto out_cleanup_disk;
/* Show this loop device. */
mutex_lock(&loop_ctl_mutex);
lo->idr_visible = true;
mutex_unlock(&loop_ctl_mutex);
return i;
out_cleanup_disk:
blk_cleanup_disk(disk);
out_cleanup_tags:
blk_mq_free_tag_set(&lo->tag_set);
out_free_idr:
mutex_lock(&loop_ctl_mutex);
idr_remove(&loop_index_idr, i);
mutex_unlock(&loop_ctl_mutex);
out_free_dev:
kfree(lo);
out:
return err;
}
static void loop_remove(struct loop_device *lo)
{
/* Make this loop device unreachable from pathname. */
del_gendisk(lo->lo_disk);
blk_cleanup_disk(lo->lo_disk);
blk_mq_free_tag_set(&lo->tag_set);
mutex_lock(&loop_ctl_mutex);
idr_remove(&loop_index_idr, lo->lo_number);
mutex_unlock(&loop_ctl_mutex);
/* There is no route which can find this loop device. */
mutex_destroy(&lo->lo_mutex);
kfree(lo);
}
static void loop_probe(dev_t dev)
{
int idx = MINOR(dev) >> part_shift;
if (max_loop && idx >= max_loop)
return;
loop_add(idx);
}
static int loop_control_remove(int idx)
{
struct loop_device *lo;
int ret;
if (idx < 0) {
pr_warn_once("deleting an unspecified loop device is not supported.\n");
return -EINVAL;
}
/* Hide this loop device for serialization. */
ret = mutex_lock_killable(&loop_ctl_mutex);
if (ret)
return ret;
lo = idr_find(&loop_index_idr, idx);
if (!lo || !lo->idr_visible)
ret = -ENODEV;
else
lo->idr_visible = false;
mutex_unlock(&loop_ctl_mutex);
if (ret)
return ret;
/* Check whether this loop device can be removed. */
ret = mutex_lock_killable(&lo->lo_mutex);
if (ret)
goto mark_visible;
if (lo->lo_state != Lo_unbound ||
atomic_read(&lo->lo_refcnt) > 0) {
mutex_unlock(&lo->lo_mutex);
ret = -EBUSY;
goto mark_visible;
}
/* Mark this loop device no longer open()-able. */
lo->lo_state = Lo_deleting;
mutex_unlock(&lo->lo_mutex);
loop_remove(lo);
return 0;
mark_visible:
/* Show this loop device again. */
mutex_lock(&loop_ctl_mutex);
lo->idr_visible = true;
mutex_unlock(&loop_ctl_mutex);
return ret;
}
static int loop_control_get_free(int idx)
{
struct loop_device *lo;
int id, ret;
ret = mutex_lock_killable(&loop_ctl_mutex);
if (ret)
return ret;
idr_for_each_entry(&loop_index_idr, lo, id) {
/* Hitting a race results in creating a new loop device which is harmless. */
if (lo->idr_visible && data_race(lo->lo_state) == Lo_unbound)
goto found;
}
mutex_unlock(&loop_ctl_mutex);
return loop_add(-1);
found:
mutex_unlock(&loop_ctl_mutex);
return id;
}
static long loop_control_ioctl(struct file *file, unsigned int cmd,
unsigned long parm)
{
switch (cmd) {
case LOOP_CTL_ADD:
return loop_add(parm);
case LOOP_CTL_REMOVE:
return loop_control_remove(parm);
case LOOP_CTL_GET_FREE:
return loop_control_get_free(parm);
default:
return -ENOSYS;
}
}
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;
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 */
for (i = 0; i < nr; i++)
loop_add(i);
printk(KERN_INFO "loop: module loaded\n");
return 0;
misc_out:
misc_deregister(&loop_misc);
err_out:
return err;
}
static void __exit loop_exit(void)
{
struct loop_device *lo;
int id;
unregister_blkdev(LOOP_MAJOR, "loop");
misc_deregister(&loop_misc);
/*
* There is no need to use loop_ctl_mutex here, for nobody else can
* access loop_index_idr when this module is unloading (unless forced
* module unloading is requested). If this is not a clean unloading,
* we have no means to avoid kernel crash.
*/
idr_for_each_entry(&loop_index_idr, lo, id)
loop_remove(lo);
idr_destroy(&loop_index_idr);
}
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