Split xloop_main into separate files for pre-5.15 and 5.15+

8 files changed, 4865 insertions, 2517 deletions

diff --git a/src/kernel/CMakeLists.txt b/src/kernel/CMakeLists.txt
index 3920562..ca964b2 100644
--- a/src/kernel/CMakeLists.txt
+++ b/src/kernel/CMakeLists.txt
@@ -37,11 +37,16 @@ set(CHECKPATCH_IGNORE_WARNINGS "LINUX_VERSION_CODE"
                                "UNSPECIFIED_INT"
                                "ENOSYS")
 
+file(GLOB XLOOP_MAIN_VERSION_HEADERS ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main_*.h)
+file(GLOB XLOOP_MAIN_VERSION_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main_*.c)
+
 # xloop main Linux kernel module
 set(KERNEL_MODULE_XLOOP_SOURCE_FILES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt.c
-                                     ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main.c)
+                                     ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main.c
+                                     ${XLOOP_MAIN_VERSION_SOURCES})
 set(KERNEL_MODULE_XLOOP_HEADER_FILES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt.h
                                      ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main.h
+                                     ${XLOOP_MAIN_VERSION_HEADERS}
                                      ${CMAKE_CURRENT_SOURCE_DIR}/uapi_xloop.h)
 add_kernel_module(xloop "${KERNEL_BUILD_DIR}"
                         "${KERNEL_INSTALL_DIR}"
@@ -67,6 +72,7 @@ add_linter_fix(xloop-lint-fix-clang "${KERNEL_MODULE_XLOOP_SOURCE_FILES}"
 set(KERNEL_MODULE_XLOOP_RAW_SOURCE_FILES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt_raw.c)
 set(KERNEL_MODULE_XLOOP_RAW_HEADER_FILES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt.h
                                          ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main.h
+                                         ${XLOOP_MAIN_VERSION_HEADERS}
                                          ${CMAKE_CURRENT_SOURCE_DIR}/uapi_xloop.h)
 add_kernel_module(xloop_file_fmt_raw "${KERNEL_BUILD_DIR}"
                                      "${KERNEL_INSTALL_DIR}"
@@ -98,6 +104,7 @@ set(KERNEL_MODULE_XLOOP_QCOW_HEADER_FILES ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file
                                           ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt_qcow_main.h
                                           ${CMAKE_CURRENT_SOURCE_DIR}/xloop_file_fmt.h
                                           ${CMAKE_CURRENT_SOURCE_DIR}/xloop_main.h
+                                          ${XLOOP_MAIN_VERSION_HEADERS}
                                           ${CMAKE_CURRENT_SOURCE_DIR}/uapi_xloop.h)
 add_kernel_module(xloop_file_fmt_qcow "${KERNEL_BUILD_DIR}"
                                       "${KERNEL_INSTALL_DIR}"
diff --git a/src/kernel/xloop_file_fmt_raw.c b/src/kernel/xloop_file_fmt_raw.c
index 2fc8ace..8a53c11 100644
--- a/src/kernel/xloop_file_fmt_raw.c
+++ b/src/kernel/xloop_file_fmt_raw.c
@@ -152,6 +152,10 @@ static void __raw_file_fmt_rw_aio_complete(struct kiocb *iocb, long ret, long re
 {
 	struct xloop_cmd *cmd = container_of(iocb, struct xloop_cmd, iocb);
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+	if (cmd->css)
+		css_put(cmd->css);
+#endif
 	cmd->ret = ret;
 	__raw_file_fmt_rw_aio_do_completion(cmd);
 }
@@ -222,6 +226,10 @@ static int __raw_file_fmt_rw_aio(struct xloop_device *xlo, struct xloop_cmd *cmd
 	cmd->iocb.ki_complete = __raw_file_fmt_rw_aio_complete;
 	cmd->iocb.ki_flags = IOCB_DIRECT;
 	cmd->iocb.ki_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+	if (cmd->css)
+		kthread_associate_blkcg(cmd->css);
+#endif
 
 	if (rw == WRITE)
 		ret = call_write_iter(file, &cmd->iocb, &iter);
@@ -229,6 +237,9 @@ static int __raw_file_fmt_rw_aio(struct xloop_device *xlo, struct xloop_cmd *cmd
 		ret = call_read_iter(file, &cmd->iocb, &iter);
 
 	__raw_file_fmt_rw_aio_do_completion(cmd);
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+	kthread_associate_blkcg(NULL);
+#endif
 
 	if (ret != -EIOCBQUEUED)
 		cmd->iocb.ki_complete(&cmd->iocb, ret, 0);
diff --git a/src/kernel/xloop_main.c b/src/kernel/xloop_main.c
index d133709..b3f7963 100644
--- a/src/kernel/xloop_main.c
+++ b/src/kernel/xloop_main.c
@@ -1,2413 +1,7 @@
-// SPDX-License-Identifier: GPL-2.0
-/*
- * xloop_main.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_xloop_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 xloop devices now dynamic via max_xloop module parameter.
- * Russell Kroll <rkroll@exploits.org> 19990701
- *
- * Maximum number of xloop devices when compiled-in now selectable by passing
- * max_xloop=<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 xloop 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
- *
- * Support for using file formats.
- * Manuel Bentele <development@manuel-bentele.de>, 2019
- *
- * Still To Fix:
- * - Advisory locking is ignored here.
- * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
- *
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#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 <linux/version.h>
-#ifdef CONFIG_DEBUG_FS
-#include <linux/debugfs.h>
-#endif
-
-#include <xloop/version.h>
-
-#include "xloop_file_fmt.h"
-#include "xloop_main.h"
-
-#include <linux/uaccess.h>
-
-#define XLOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
-
-static DEFINE_IDR(xloop_index_idr);
-static DEFINE_MUTEX(xloop_ctl_mutex);
-static DEFINE_MUTEX(xloop_validate_mutex);
-
-/**
- * xloop_global_lock_killable() - take locks for safe xloop_validate_file() test
- *
- * @xlo: struct xloop_device
- * @global: true if @xlo is about to bind another "struct xloop_device", false otherwise
- *
- * Returns 0 on success, -EINTR otherwise.
- *
- * Since xloop_validate_file() traverses on other "struct xloop_device" if
- * is_xloop_device() is true, we need a global lock for serializing concurrent
- * xloop_configure()/xloop_change_fd()/__xloop_clr_fd() calls.
- */
-static int xloop_global_lock_killable(struct xloop_device *xlo, bool global)
-{
-	int err;
-
-	if (global) {
-		err = mutex_lock_killable(&xloop_validate_mutex);
-		if (err)
-			return err;
-	}
-	err = mutex_lock_killable(&xlo->xlo_mutex);
-	if (err && global)
-		mutex_unlock(&xloop_validate_mutex);
-	return err;
-}
-
-/**
- * xloop_global_unlock() - release locks taken by xloop_global_lock_killable()
- *
- * @xlo: struct xloop_device
- * @global: true if @xlo was about to bind another "struct xloop_device", false otherwise
- */
-static void xloop_global_unlock(struct xloop_device *xlo, bool global)
-{
-	mutex_unlock(&xlo->xlo_mutex);
-	if (global)
-		mutex_unlock(&xloop_validate_mutex);
-}
-
-static int max_part;
-static int part_shift;
-
-struct device *xloop_device_to_dev(struct xloop_device *xlo)
-{
-	return disk_to_dev(xlo->xlo_disk);
-}
-EXPORT_SYMBOL(xloop_device_to_dev);
-
-static int transfer_xor(struct xloop_device *xlo, int cmd,
-			struct page *raw_page, unsigned raw_off,
-			struct page *xloop_page, unsigned xloop_off,
-			int size, sector_t real_block)
-{
-	char *raw_buf = kmap_atomic(raw_page) + raw_off;
-	char *xloop_buf = kmap_atomic(xloop_page) + xloop_off;
-	char *in, *out, *key;
-	int i, keysize;
-
-	if (cmd == READ) {
-		in = raw_buf;
-		out = xloop_buf;
-	} else {
-		in = xloop_buf;
-		out = raw_buf;
-	}
-
-	key = xlo->xlo_encrypt_key;
-	keysize = xlo->xlo_encrypt_key_size;
-	for (i = 0; i < size; i++)
-		*out++ = *in++ ^ key[(i & 511) % keysize];
-
-	kunmap_atomic(xloop_buf);
-	kunmap_atomic(raw_buf);
-	cond_resched();
-	return 0;
-}
-
-static int xor_init(struct xloop_device *xlo, const struct xloop_info64 *info)
-{
-	if (unlikely(info->xlo_encrypt_key_size <= 0))
-		return -EINVAL;
-	return 0;
-}
-
-static struct xloop_func_table none_funcs = {
-	.number = XLO_CRYPT_NONE,
-};
-
-static struct xloop_func_table xor_funcs = {
-	.number = XLO_CRYPT_XOR,
-	.transfer = transfer_xor,
-	.init = xor_init
-};
-
-/* xfer_funcs[0] is special - its release function is never called */
-static struct xloop_func_table *xfer_funcs[MAX_XLO_CRYPT] = {
-	&none_funcs,
-	&xor_funcs
-};
-
-static loff_t get_xloop_size(struct xloop_device *xlo, struct file *file)
-{
-	return xloop_file_fmt_sector_size(xlo->xlo_fmt, file, xlo->xlo_offset, xlo->xlo_sizelimit);
-}
-
-static void __xloop_update_dio(struct xloop_device *xlo, bool dio)
-{
-	struct file *file = xlo->xlo_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 xlo_offset is aligned with the
-	 * logical I/O size of backing device, and the logical block
-	 * size of xloop is bigger than the backing device's and the xloop
-	 * 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(xlo->xlo_queue) >= sb_bsize &&
-				!(xlo->xlo_offset & dio_align) &&
-				mapping->a_ops->direct_IO &&
-				!xlo->transfer)
-			use_dio = true;
-		else
-			use_dio = false;
-	} else {
-		use_dio = false;
-	}
-
-	if (xlo->use_dio == use_dio)
-		return;
-
-	/* flush dirty pages before changing direct IO */
-	xloop_file_fmt_flush(xlo->xlo_fmt);
-
-	/*
-	 * The flag of XLO_FLAGS_DIRECT_IO is handled similarly with
-	 * XLO_FLAGS_READ_ONLY, both are set from kernel, and xlosetup
-	 * will get updated by ioctl(XLOOP_GET_STATUS)
-	 */
-	if (xlo->xlo_state == Xlo_bound)
-		blk_mq_freeze_queue(xlo->xlo_queue);
-	xlo->use_dio = use_dio;
-	if (use_dio) {
-		blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
-		xlo->xlo_flags |= XLO_FLAGS_DIRECT_IO;
-	} else {
-		blk_queue_flag_set(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
-		xlo->xlo_flags &= ~XLO_FLAGS_DIRECT_IO;
-	}
-	if (xlo->xlo_state == Xlo_bound)
-		blk_mq_unfreeze_queue(xlo->xlo_queue);
-}
-
-/**
- * xloop_set_size() - sets device size and notifies userspace
- * @xlo: struct xloop_device to set the size for
- * @size: new size of the xloop device
- *
- * Callers must validate that the size passed into this function fits into
- * a sector_t, eg using xloop_validate_size()
- */
-static void xloop_set_size(struct xloop_device *xlo, loff_t size)
-{
-	if (!set_capacity_and_notify(xlo->xlo_disk, size))
-		kobject_uevent(&disk_to_dev(xlo->xlo_disk)->kobj, KOBJ_CHANGE);
-}
-
-static inline int
-xlo_do_transfer(struct xloop_device *xlo, int cmd,
-	       struct page *rpage, unsigned roffs,
-	       struct page *lpage, unsigned loffs,
-	       int size, sector_t rblock)
-{
-	int ret;
-
-	ret = xlo->transfer(xlo, cmd, rpage, roffs, lpage, loffs, size, rblock);
-	if (likely(!ret))
-		return 0;
-
-	pr_err_ratelimited("Transfer error at byte offset %llu, length %i.\n",
-		(unsigned long long)rblock << 9, size);
-	return ret;
-}
-
-static void xlo_complete_rq(struct request *rq)
-{
-	struct xloop_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 int do_req_filebacked(struct xloop_device *xlo, struct request *rq)
-{
-	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
-
-	/*
-	 * xlo_write_simple and xlo_read_simple should have been covered
-	 * by io submit style function like xloop_file_fmt_read_aio(), one
-	 * blocker is that xloop_file_fmt_read() 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 xloop_file_fmt_flush(xlo->xlo_fmt);
-	case REQ_OP_WRITE_ZEROES:
-		return xloop_file_fmt_write_zeros(xlo->xlo_fmt, rq);
-	case REQ_OP_DISCARD:
-		return xloop_file_fmt_discard(xlo->xlo_fmt, rq);
-	case REQ_OP_WRITE:
-		if (cmd->use_aio)
-			return xloop_file_fmt_write_aio(xlo->xlo_fmt, rq);
-		else
-			return xloop_file_fmt_write(xlo->xlo_fmt, rq);
-	case REQ_OP_READ:
-		if (cmd->use_aio)
-			return xloop_file_fmt_read_aio(xlo->xlo_fmt, rq);
-		else
-			return xloop_file_fmt_read(xlo->xlo_fmt, rq);
-	default:
-		WARN_ON_ONCE(1);
-		return -EIO;
-	}
-}
-
-static inline void xloop_update_dio(struct xloop_device *xlo)
-{
-	__xloop_update_dio(xlo, (xlo->xlo_backing_file->f_flags & O_DIRECT) |
-				xlo->use_dio);
-}
-
-static void xloop_reread_partitions(struct xloop_device *xlo)
-{
-	int rc;
-
-	mutex_lock(&xlo->xlo_disk->open_mutex);
-	rc = bdev_disk_changed(xlo->xlo_disk, false);
-	mutex_unlock(&xlo->xlo_disk->open_mutex);
-	if (rc)
-		dev_warn(xloop_device_to_dev(xlo),
-			"partition scan of xloop%d (%s) failed (rc=%d)\n",
-			xlo->xlo_number, xlo->xlo_file_name, rc);
-}
-
-static inline int is_xloop_device(struct file *file)
-{
-	struct inode *i = file->f_mapping->host;
-
-	return i && S_ISBLK(i->i_mode) && imajor(i) == XLOOP_MAJOR;
-}
-
-static int xloop_validate_file(struct file *file, struct block_device *bdev)
-{
-	struct inode	*inode = file->f_mapping->host;
-	struct file	*f = file;
-
-	/* Avoid recursion */
-	while (is_xloop_device(f)) {
-		struct xloop_device *l;
-
-		lockdep_assert_held(&xloop_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->xlo_state != Xlo_bound)
-			return -EINVAL;
-		/* Order wrt setting xlo->xlo_backing_file in xloop_configure(). */
-		rmb();
-		f = l->xlo_backing_file;
-	}
-	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
-		return -EINVAL;
-	return 0;
-}
-
-/*
- * xloop_change_fd switched the backing store of a xloopback 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 xloop device is used read-only, and if the
- * new backing store is the same size and type as the old backing store.
- */
-static int xloop_change_fd(struct xloop_device *xlo, struct block_device *bdev,
-			  unsigned int arg)
-{
-	struct file *file = fget(arg);
-	struct file *old_file;
-	int error;
-	bool partscan;
-	bool is_xloop;
-
-	if (!file)
-		return -EBADF;
-	is_xloop = is_xloop_device(file);
-	error = xloop_global_lock_killable(xlo, is_xloop);
-	if (error)
-		goto out_putf;
-	error = -ENXIO;
-	if (xlo->xlo_state != Xlo_bound)
-		goto out_err;
-
-	/* the xloop device has to be read-only */
-	error = -EINVAL;
-	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY))
-		goto out_err;
-
-	error = xloop_validate_file(file, bdev);
-	if (error)
-		goto out_err;
-
-	old_file = xlo->xlo_backing_file;
-
-	error = -EINVAL;
-
-	/* size of the new backing store needs to be the same */
-	if (get_xloop_size(xlo, file) != get_xloop_size(xlo, old_file))
-		goto out_err;
-
-	/* and ... switch */
-	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
-	blk_mq_freeze_queue(xlo->xlo_queue);
-	mapping_set_gfp_mask(old_file->f_mapping, xlo->old_gfp_mask);
-	xlo->xlo_backing_file = file;
-	xlo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
-	mapping_set_gfp_mask(file->f_mapping,
-			     xlo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
-	xloop_update_dio(xlo);
-	blk_mq_unfreeze_queue(xlo->xlo_queue);
-	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
-	xloop_global_unlock(xlo, is_xloop);
-
-	/*
-	 * Flush xloop_validate_file() before fput(), for l->xlo_backing_file
-	 * might be pointing at old_file which might be the last reference.
-	 */
-	if (!is_xloop) {
-		mutex_lock(&xloop_validate_mutex);
-		mutex_unlock(&xloop_validate_mutex);
-	}
-	/*
-	 * We must drop file reference outside of xlo_mutex as dropping
-	 * the file ref can take open_mutex which creates circular locking
-	 * dependency.
-	 */
-	fput(old_file);
-	if (partscan)
-		xloop_reread_partitions(xlo);
-	return 0;
-
-out_err:
-	xloop_global_unlock(xlo, is_xloop);
-out_putf:
-	fput(file);
-	return error;
-}
-
-/* xloop sysfs attributes */
-
-static ssize_t xloop_attr_show(struct device *dev, char *page,
-			      ssize_t (*callback)(struct xloop_device *, char *))
-{
-	struct gendisk *disk = dev_to_disk(dev);
-	struct xloop_device *xlo = disk->private_data;
-
-	return callback(xlo, page);
-}
-
-#define XLOOP_ATTR_RO(_name)						\
-static ssize_t xloop_attr_##_name##_show(struct xloop_device *, char *);	\
-static ssize_t xloop_attr_do_show_##_name(struct device *d,		\
-				struct device_attribute *attr, char *b)	\
-{									\
-	return xloop_attr_show(d, b, xloop_attr_##_name##_show);		\
-}									\
-static struct device_attribute xloop_attr_##_name =			\
-	__ATTR(_name, 0444, xloop_attr_do_show_##_name, NULL);
-
-static ssize_t xloop_attr_backing_file_show(struct xloop_device *xlo, char *buf)
-{
-	ssize_t ret;
-	char *p = NULL;
-
-	spin_lock_irq(&xlo->xlo_lock);
-	if (xlo->xlo_backing_file)
-		p = file_path(xlo->xlo_backing_file, buf, PAGE_SIZE - 1);
-	spin_unlock_irq(&xlo->xlo_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 xloop_attr_file_fmt_type_show(struct xloop_device *xlo, char *buf)
-{
-	ssize_t len = 0;
-
-	len = xloop_file_fmt_print_type(xlo->xlo_fmt->file_fmt_type, buf);
-	len += sprintf(buf + len, "\n");
-
-	return len;
-}
-
-static ssize_t xloop_attr_offset_show(struct xloop_device *xlo, char *buf)
-{
-	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_offset);
-}
-
-static ssize_t xloop_attr_sizelimit_show(struct xloop_device *xlo, char *buf)
-{
-	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_sizelimit);
-}
-
-static ssize_t xloop_attr_autoclear_show(struct xloop_device *xlo, char *buf)
-{
-	int autoclear = (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR);
-
-	return sprintf(buf, "%s\n", autoclear ? "1" : "0");
-}
-
-static ssize_t xloop_attr_partscan_show(struct xloop_device *xlo, char *buf)
-{
-	int partscan = (xlo->xlo_flags & XLO_FLAGS_PARTSCAN);
-
-	return sprintf(buf, "%s\n", partscan ? "1" : "0");
-}
-
-static ssize_t xloop_attr_dio_show(struct xloop_device *xlo, char *buf)
-{
-	int dio = (xlo->xlo_flags & XLO_FLAGS_DIRECT_IO);
-
-	return sprintf(buf, "%s\n", dio ? "1" : "0");
-}
-
-XLOOP_ATTR_RO(backing_file);
-XLOOP_ATTR_RO(file_fmt_type);
-XLOOP_ATTR_RO(offset);
-XLOOP_ATTR_RO(sizelimit);
-XLOOP_ATTR_RO(autoclear);
-XLOOP_ATTR_RO(partscan);
-XLOOP_ATTR_RO(dio);
-
-static struct attribute *xloop_attrs[] = {
-	&xloop_attr_backing_file.attr,
-	&xloop_attr_file_fmt_type.attr,
-	&xloop_attr_offset.attr,
-	&xloop_attr_sizelimit.attr,
-	&xloop_attr_autoclear.attr,
-	&xloop_attr_partscan.attr,
-	&xloop_attr_dio.attr,
-	NULL,
-};
-
-static struct attribute_group xloop_attribute_group = {
-	.name = "xloop",
-	.attrs = xloop_attrs,
-};
-
-static void xloop_sysfs_init(struct xloop_device *xlo)
-{
-	xlo->sysfs_inited = !sysfs_create_group(&disk_to_dev(xlo->xlo_disk)->kobj,
-						&xloop_attribute_group);
-}
-
-static void xloop_sysfs_exit(struct xloop_device *xlo)
-{
-	if (xlo->sysfs_inited)
-		sysfs_remove_group(&disk_to_dev(xlo->xlo_disk)->kobj,
-				   &xloop_attribute_group);
-}
-
-static void xloop_config_discard(struct xloop_device *xlo)
-{
-	struct file *file = xlo->xlo_backing_file;
-	struct inode *inode = file->f_mapping->host;
-	struct request_queue *q = xlo->xlo_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 xloop discards result in blkdev_issue_zeroout(),
-	 * not blkdev_issue_discard(). This maintains consistent behavior with
-	 * file-backed xloop devices: discarded regions read back as zero.
-	 */
-	if (S_ISBLK(inode->i_mode) && !xlo->xlo_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 || xlo->xlo_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;
-}
-
-struct xloop_worker {
-	struct rb_node rb_node;
-	struct work_struct work;
-	struct list_head cmd_list;
-	struct list_head idle_list;
-	struct xloop_device *xlo;
-	struct cgroup_subsys_state *blkcg_css;
-	unsigned long last_ran_at;
-};
-
-static void xloop_workfn(struct work_struct *work);
-static void xloop_rootcg_workfn(struct work_struct *work);
-static void xloop_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;
-}
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+#include "xloop_main_4.18.c"
 #else
-static inline int queue_on_root_worker(struct cgroup_subsys_state *css)
-{
-	return !css;
-}
-#endif
-
-static void xloop_queue_work(struct xloop_device *xlo, struct xloop_cmd *cmd)
-{
-	struct rb_node **node = &(xlo->worker_tree.rb_node), *parent = NULL;
-	struct xloop_worker *cur_worker, *worker = NULL;
-	struct work_struct *work;
-	struct list_head *cmd_list;
-
-	spin_lock_irq(&xlo->xlo_work_lock);
-
-	if (queue_on_root_worker(cmd->blkcg_css))
-		goto queue_work;
-
-	node = &xlo->worker_tree.rb_node;
-
-	while (*node) {
-		parent = *node;
-		cur_worker = container_of(*node, struct xloop_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 xloop_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, xloop_workfn);
-	INIT_LIST_HEAD(&worker->cmd_list);
-	INIT_LIST_HEAD(&worker->idle_list);
-	worker->xlo = xlo;
-	rb_link_node(&worker->rb_node, parent, node);
-	rb_insert_color(&worker->rb_node, &xlo->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 = &xlo->rootcg_work;
-		cmd_list = &xlo->rootcg_cmd_list;
-	}
-	list_add_tail(&cmd->list_entry, cmd_list);
-	queue_work(xlo->workqueue, work);
-	spin_unlock_irq(&xlo->xlo_work_lock);
-}
-
-static void xloop_update_rotational(struct xloop_device *xlo)
-{
-	struct file *file = xlo->xlo_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 = xlo->xlo_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
-xloop_release_xfer(struct xloop_device *xlo)
-{
-	int err = 0;
-	struct xloop_func_table *xfer = xlo->xlo_encryption;
-
-	if (xfer) {
-		if (xfer->release)
-			err = xfer->release(xlo);
-		xlo->transfer = NULL;
-		xlo->xlo_encryption = NULL;
-		module_put(xfer->owner);
-	}
-	return err;
-}
-
-static int
-xloop_init_xfer(struct xloop_device *xlo, struct xloop_func_table *xfer,
-	       const struct xloop_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(xlo, i);
-		if (err)
-			module_put(owner);
-		else
-			xlo->xlo_encryption = xfer;
-	}
-	return err;
-}
-
-/**
- * xloop_set_status_from_info - configure device from xloop_info
- * @xlo: struct xloop_device to configure
- * @info: struct xloop_info64 to configure the device with
- *
- * Configures the xloop device parameters according to the passed
- * in xloop_info64 configuration.
- */
-static int
-xloop_set_status_from_info(struct xloop_device *xlo,
-			  const struct xloop_info64 *info)
-{
-	int err;
-	struct xloop_func_table *xfer;
-	kuid_t uid = current_uid();
-
-	if ((unsigned int) info->xlo_encrypt_key_size > XLO_KEY_SIZE)
-		return -EINVAL;
-
-	err = xloop_release_xfer(xlo);
-	if (err)
-		return err;
-
-	if (info->xlo_encrypt_type) {
-		unsigned int type = info->xlo_encrypt_type;
-
-		if (type >= MAX_XLO_CRYPT)
-			return -EINVAL;
-		xfer = xfer_funcs[type];
-		if (xfer == NULL)
-			return -EINVAL;
-	} else
-		xfer = NULL;
-
-	err = xloop_init_xfer(xlo, xfer, info);
-	if (err)
-		return err;
-
-	xlo->xlo_offset = info->xlo_offset;
-	xlo->xlo_sizelimit = info->xlo_sizelimit;
-	memcpy(xlo->xlo_file_name, info->xlo_file_name, XLO_NAME_SIZE);
-	memcpy(xlo->xlo_crypt_name, info->xlo_crypt_name, XLO_NAME_SIZE);
-	xlo->xlo_file_name[XLO_NAME_SIZE-1] = 0;
-	xlo->xlo_crypt_name[XLO_NAME_SIZE-1] = 0;
-
-	if (!xfer)
-		xfer = &none_funcs;
-	xlo->transfer = xfer->transfer;
-	xlo->ioctl = xfer->ioctl;
-
-	xlo->xlo_flags = info->xlo_flags;
-
-	xlo->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
-	xlo->xlo_init[0] = info->xlo_init[0];
-	xlo->xlo_init[1] = info->xlo_init[1];
-	if (info->xlo_encrypt_key_size) {
-		memcpy(xlo->xlo_encrypt_key, info->xlo_encrypt_key,
-		       info->xlo_encrypt_key_size);
-		xlo->xlo_key_owner = uid;
-	}
-
-	return 0;
-}
-
-static int xloop_configure(struct xloop_device *xlo, fmode_t mode,
-			  struct block_device *bdev,
-			  const struct xloop_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_xloop;
-
-	if (!file)
-		return -EBADF;
-	is_xloop = is_xloop_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, xloop_configure);
-		if (error)
-			goto out_putf;
-	}
-
-	error = xloop_global_lock_killable(xlo, is_xloop);
-	if (error)
-		goto out_bdev;
-
-	error = -EBUSY;
-	if (xlo->xlo_state != Xlo_unbound)
-		goto out_unlock;
-
-	error = xloop_validate_file(file, bdev);
-	if (error)
-		goto out_unlock;
-
-	mapping = file->f_mapping;
-	inode = mapping->host;
-
-	if ((config->info.xlo_flags & ~XLOOP_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 = xloop_set_status_from_info(xlo, &config->info);
-	if (error)
-		goto out_unlock;
-
-	if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
-	    !file->f_op->write_iter)
-		xlo->xlo_flags |= XLO_FLAGS_READ_ONLY;
-
-	xlo->workqueue = alloc_workqueue("xloop%d",
-					WQ_UNBOUND | WQ_FREEZABLE,
-					0,
-					xlo->xlo_number);
-	if (!xlo->workqueue) {
-		error = -ENOMEM;
-		goto out_unlock;
-	}
-
-	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
-	set_disk_ro(xlo->xlo_disk, (xlo->xlo_flags & XLO_FLAGS_READ_ONLY) != 0);
-
-	INIT_WORK(&xlo->rootcg_work, xloop_rootcg_workfn);
-	INIT_LIST_HEAD(&xlo->rootcg_cmd_list);
-	INIT_LIST_HEAD(&xlo->idle_worker_list);
-	xlo->worker_tree = RB_ROOT;
-	timer_setup(&xlo->timer, xloop_free_idle_workers,
-		TIMER_DEFERRABLE);
-	xlo->use_dio = xlo->xlo_flags & XLO_FLAGS_DIRECT_IO;
-	xlo->xlo_device = bdev;
-	xlo->xlo_backing_file = file;
-	xlo->old_gfp_mask = mapping_gfp_mask(mapping);
-	mapping_set_gfp_mask(mapping, xlo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
-
-	error = xloop_file_fmt_init(xlo->xlo_fmt, config->info.xlo_file_fmt_type);
-	if (error)
-		goto out_unlock;
-
-	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY) && file->f_op->fsync)
-		blk_queue_write_cache(xlo->xlo_queue, true, false);
-
-	if (config->block_size)
-		bsize = config->block_size;
-	else if ((xlo->xlo_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(xlo->xlo_queue, bsize);
-	blk_queue_physical_block_size(xlo->xlo_queue, bsize);
-	blk_queue_io_min(xlo->xlo_queue, bsize);
-
-	xloop_config_discard(xlo);
-	xloop_update_rotational(xlo);
-	xloop_update_dio(xlo);
-	xloop_sysfs_init(xlo);
-
-	size = get_xloop_size(xlo, file);
-	xloop_set_size(xlo, size);
-
-	/* Order wrt reading xlo_state in xloop_validate_file(). */
-	wmb();
-
-	xlo->xlo_state = Xlo_bound;
-	if (part_shift)
-		xlo->xlo_flags |= XLO_FLAGS_PARTSCAN;
-	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
-	if (partscan)
-		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
-
-	xloop_global_unlock(xlo, is_xloop);
-	if (partscan)
-		xloop_reread_partitions(xlo);
-	if (!(mode & FMODE_EXCL))
-		bd_abort_claiming(bdev, xloop_configure);
-	return 0;
-
-out_unlock:
-	xloop_global_unlock(xlo, is_xloop);
-out_bdev:
-	if (!(mode & FMODE_EXCL))
-		bd_abort_claiming(bdev, xloop_configure);
-out_putf:
-	fput(file);
-	/* This is safe: open() is still holding a reference. */
-	module_put(THIS_MODULE);
-	return error;
-}
-
-static int __xloop_clr_fd(struct xloop_device *xlo, bool release)
-{
-	struct file *filp = NULL;
-	gfp_t gfp = xlo->old_gfp_mask;
-	struct block_device *bdev = xlo->xlo_device;
-	int err = 0;
-	bool partscan = false;
-	int xlo_number;
-	struct xloop_worker *pos, *worker;
-
-	/*
-	 * Flush xloop_configure() and xloop_change_fd(). It is acceptable for
-	 * xloop_validate_file() to succeed, for actual clear operation has not
-	 * started yet.
-	 */
-	mutex_lock(&xloop_validate_mutex);
-	mutex_unlock(&xloop_validate_mutex);
-	/*
-	 * xloop_validate_file() now fails because l->xlo_state != Xlo_bound
-	 * became visible.
-	 */
-
-	mutex_lock(&xlo->xlo_mutex);
-	if (WARN_ON_ONCE(xlo->xlo_state != Xlo_rundown)) {
-		err = -ENXIO;
-		goto out_unlock;
-	}
-
-	filp = xlo->xlo_backing_file;
-	if (filp == NULL) {
-		err = -EINVAL;
-		goto out_unlock;
-	}
-
-	if (test_bit(QUEUE_FLAG_WC, &xlo->xlo_queue->queue_flags))
-		blk_queue_write_cache(xlo->xlo_queue, false, false);
-
-	/* freeze request queue during the transition */
-	blk_mq_freeze_queue(xlo->xlo_queue);
-
-	xloop_file_fmt_exit(xlo->xlo_fmt);
-
-	destroy_workqueue(xlo->workqueue);
-	spin_lock_irq(&xlo->xlo_work_lock);
-	list_for_each_entry_safe(worker, pos, &xlo->idle_worker_list,
-				idle_list) {
-		list_del(&worker->idle_list);
-		rb_erase(&worker->rb_node, &xlo->worker_tree);
-		css_put(worker->blkcg_css);
-		kfree(worker);
-	}
-	spin_unlock_irq(&xlo->xlo_work_lock);
-	del_timer_sync(&xlo->timer);
-
-	spin_lock_irq(&xlo->xlo_lock);
-	xlo->xlo_backing_file = NULL;
-	spin_unlock_irq(&xlo->xlo_lock);
-
-	xloop_release_xfer(xlo);
-	xlo->transfer = NULL;
-	xlo->ioctl = NULL;
-	xlo->xlo_device = NULL;
-	xlo->xlo_encryption = NULL;
-	xlo->xlo_offset = 0;
-	xlo->xlo_sizelimit = 0;
-	xlo->xlo_encrypt_key_size = 0;
-	memset(xlo->xlo_encrypt_key, 0, XLO_KEY_SIZE);
-	memset(xlo->xlo_crypt_name, 0, XLO_NAME_SIZE);
-	memset(xlo->xlo_file_name, 0, XLO_NAME_SIZE);
-	blk_queue_logical_block_size(xlo->xlo_queue, 512);
-	blk_queue_physical_block_size(xlo->xlo_queue, 512);
-	blk_queue_io_min(xlo->xlo_queue, 512);
-	if (bdev) {
-		invalidate_bdev(bdev);
-		bdev->bd_inode->i_mapping->wb_err = 0;
-	}
-	set_capacity(xlo->xlo_disk, 0);
-	xloop_sysfs_exit(xlo);
-	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(xlo->xlo_queue);
-
-	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN && bdev;
-	xlo_number = xlo->xlo_number;
-	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
-out_unlock:
-	mutex_unlock(&xlo->xlo_mutex);
-	if (partscan) {
-		/*
-		 * open_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, xlo_refcnt
-		 * must be at least one and it can only become zero when the
-		 * current holder is released.
-		 */
-		if (!release)
-			mutex_lock(&xlo->xlo_disk->open_mutex);
-		err = bdev_disk_changed(xlo->xlo_disk, false);
-		if (!release)
-			mutex_unlock(&xlo->xlo_disk->open_mutex);
-		if (err)
-			dev_warn(xloop_device_to_dev(xlo),
-				"partition scan of xloop%d failed (rc=%d)\n",
-				xlo_number, err);
-		/* Device is gone, no point in returning error */
-		err = 0;
-	}
-
-	/*
-	 * xlo->xlo_state is set to Xlo_unbound here after above partscan has
-	 * finished.
-	 *
-	 * There cannot be anybody else entering __xloop_clr_fd() as
-	 * xlo->xlo_backing_file is already cleared and Xlo_rundown state
-	 * protects us from all the other places trying to change the 'xlo'
-	 * device.
-	 */
-	mutex_lock(&xlo->xlo_mutex);
-	xlo->xlo_flags = 0;
-	if (!part_shift)
-		xlo->xlo_disk->flags |= GENHD_FL_NO_PART_SCAN;
-	xlo->xlo_state = Xlo_unbound;
-	mutex_unlock(&xlo->xlo_mutex);
-
-	/*
-	 * Need not hold xlo_mutex to fput backing file. Calling fput holding
-	 * xlo_mutex triggers a circular lock dependency possibility warning as
-	 * fput can take open_mutex which is usually taken before xlo_mutex.
-	 */
-	if (filp)
-		fput(filp);
-	return err;
-}
-
-static int xloop_clr_fd(struct xloop_device *xlo)
-{
-	int err;
-
-	err = mutex_lock_killable(&xlo->xlo_mutex);
-	if (err)
-		return err;
-	if (xlo->xlo_state != Xlo_bound) {
-		mutex_unlock(&xlo->xlo_mutex);
-		return -ENXIO;
-	}
-	/*
-	 * If we've explicitly asked to tear down the xloop 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 xloopback device whenever they appear. xfstests is notorious for
-	 * failing tests because blkid via udev races with a xlosetup
-	 * <dev>/do something like mkfs/xlosetup -d <dev> causing the xlosetup -d
-	 * command to fail with EBUSY.
-	 */
-	if (atomic_read(&xlo->xlo_refcnt) > 1) {
-		xlo->xlo_flags |= XLO_FLAGS_AUTOCLEAR;
-		mutex_unlock(&xlo->xlo_mutex);
-		return 0;
-	}
-	xlo->xlo_state = Xlo_rundown;
-	mutex_unlock(&xlo->xlo_mutex);
-
-	return __xloop_clr_fd(xlo, false);
-}
-
-static int
-xloop_set_status(struct xloop_device *xlo, const struct xloop_info64 *info)
-{
-	int err;
-	kuid_t uid = current_uid();
-	int prev_xlo_flags;
-	bool partscan = false;
-	bool size_changed = false;
-
-	err = mutex_lock_killable(&xlo->xlo_mutex);
-	if (err)
-		return err;
-	if (xlo->xlo_encrypt_key_size &&
-	    !uid_eq(xlo->xlo_key_owner, uid) &&
-	    !capable(CAP_SYS_ADMIN)) {
-		err = -EPERM;
-		goto out_unlock;
-	}
-	if (xlo->xlo_state != Xlo_bound) {
-		err = -ENXIO;
-		goto out_unlock;
-	}
-
-	if (xlo->xlo_offset != info->xlo_offset ||
-	    xlo->xlo_sizelimit != info->xlo_sizelimit) {
-		size_changed = true;
-		sync_blockdev(xlo->xlo_device);
-		invalidate_bdev(xlo->xlo_device);
-	}
-
-	/* I/O need to be drained during transfer transition */
-	blk_mq_freeze_queue(xlo->xlo_queue);
-
-	if (size_changed && xlo->xlo_device->bd_inode->i_mapping->nrpages) {
-		/* If any pages were dirtied after invalidate_bdev(), try again */
-		err = -EAGAIN;
-		dev_warn(xloop_device_to_dev(xlo),
-			"xloop%d (%s) has still dirty pages (nrpages=%lu)\n",
-			xlo->xlo_number, xlo->xlo_file_name,
-			xlo->xlo_device->bd_inode->i_mapping->nrpages);
-		goto out_unfreeze;
-	}
-
-	prev_xlo_flags = xlo->xlo_flags;
-
-	err = xloop_set_status_from_info(xlo, info);
-	if (err)
-		goto out_unfreeze;
-
-	/* Mask out flags that can't be set using XLOOP_SET_STATUS. */
-	xlo->xlo_flags &= XLOOP_SET_STATUS_SETTABLE_FLAGS;
-	/* For those flags, use the previous values instead */
-	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_SETTABLE_FLAGS;
-	/* For flags that can't be cleared, use previous values too */
-	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_CLEARABLE_FLAGS;
-
-	if (xlo->xlo_fmt->file_fmt_type != info->xlo_file_fmt_type) {
-		/* xloop file format has changed, so change file format driver */
-		err = xloop_file_fmt_change(xlo->xlo_fmt, info->xlo_file_fmt_type);
-		if (err)
-			goto out_unfreeze;
-
-		/* After change of the file format, recalculate the capacity of the xloop device. */
-		size_changed = true;
-	}
-
-	if (size_changed) {
-		loff_t new_size = get_xloop_size(xlo, xlo->xlo_backing_file);
-
-		xloop_set_size(xlo, new_size);
-	}
-
-	xloop_config_discard(xlo);
-
-	/* update dio if xlo_offset or transfer is changed */
-	__xloop_update_dio(xlo, xlo->use_dio);
-
-out_unfreeze:
-	blk_mq_unfreeze_queue(xlo->xlo_queue);
-
-	if (!err && (xlo->xlo_flags & XLO_FLAGS_PARTSCAN) &&
-	     !(prev_xlo_flags & XLO_FLAGS_PARTSCAN)) {
-		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
-		partscan = true;
-	}
-out_unlock:
-	mutex_unlock(&xlo->xlo_mutex);
-	if (partscan)
-		xloop_reread_partitions(xlo);
-
-	return err;
-}
-
-static int
-xloop_get_status(struct xloop_device *xlo, struct xloop_info64 *info)
-{
-	struct path path;
-	struct kstat stat;
-	int ret;
-
-	ret = mutex_lock_killable(&xlo->xlo_mutex);
-	if (ret)
-		return ret;
-	if (xlo->xlo_state != Xlo_bound) {
-		mutex_unlock(&xlo->xlo_mutex);
-		return -ENXIO;
-	}
-
-	memset(info, 0, sizeof(*info));
-	info->xlo_number = xlo->xlo_number;
-	info->xlo_offset = xlo->xlo_offset;
-	info->xlo_sizelimit = xlo->xlo_sizelimit;
-	info->xlo_flags = xlo->xlo_flags;
-	memcpy(info->xlo_file_name, xlo->xlo_file_name, XLO_NAME_SIZE);
-	memcpy(info->xlo_crypt_name, xlo->xlo_crypt_name, XLO_NAME_SIZE);
-	info->xlo_encrypt_type =
-		xlo->xlo_encryption ? xlo->xlo_encryption->number : 0;
-	if (xlo->xlo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
-		info->xlo_encrypt_key_size = xlo->xlo_encrypt_key_size;
-		memcpy(info->xlo_encrypt_key, xlo->xlo_encrypt_key,
-		       xlo->xlo_encrypt_key_size);
-	}
-
-	/* Drop xlo_mutex while we call into the filesystem. */
-	path = xlo->xlo_backing_file->f_path;
-	path_get(&path);
-	mutex_unlock(&xlo->xlo_mutex);
-	ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
-	if (!ret) {
-		info->xlo_device = huge_encode_dev(stat.dev);
-		info->xlo_inode = stat.ino;
-		info->xlo_rdevice = huge_encode_dev(stat.rdev);
-	}
-	path_put(&path);
-	return ret;
-}
-
-static void
-xloop_info64_from_old(const struct xloop_info *info, struct xloop_info64 *info64)
-{
-	memset(info64, 0, sizeof(*info64));
-	info64->xlo_number = info->xlo_number;
-	info64->xlo_device = info->xlo_device;
-	info64->xlo_inode = info->xlo_inode;
-	info64->xlo_rdevice = info->xlo_rdevice;
-	info64->xlo_offset = info->xlo_offset;
-	info64->xlo_sizelimit = 0;
-	info64->xlo_encrypt_type = info->xlo_encrypt_type;
-	info64->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
-	info64->xlo_flags = info->xlo_flags;
-	info64->xlo_init[0] = info->xlo_init[0];
-	info64->xlo_init[1] = info->xlo_init[1];
-	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
-		memcpy(info64->xlo_crypt_name, info->xlo_name, XLO_NAME_SIZE);
-	else
-		memcpy(info64->xlo_file_name, info->xlo_name, XLO_NAME_SIZE);
-	memcpy(info64->xlo_encrypt_key, info->xlo_encrypt_key, XLO_KEY_SIZE);
-}
-
-static int
-xloop_info64_to_old(const struct xloop_info64 *info64, struct xloop_info *info)
-{
-	memset(info, 0, sizeof(*info));
-	info->xlo_number = info64->xlo_number;
-	info->xlo_device = info64->xlo_device;
-	info->xlo_inode = info64->xlo_inode;
-	info->xlo_rdevice = info64->xlo_rdevice;
-	info->xlo_offset = info64->xlo_offset;
-	info->xlo_encrypt_type = info64->xlo_encrypt_type;
-	info->xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
-	info->xlo_flags = info64->xlo_flags;
-	info->xlo_init[0] = info64->xlo_init[0];
-	info->xlo_init[1] = info64->xlo_init[1];
-	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
-		memcpy(info->xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
-	else
-		memcpy(info->xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
-	memcpy(info->xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
-
-	/* error in case values were truncated */
-	if (info->xlo_device != info64->xlo_device ||
-	    info->xlo_rdevice != info64->xlo_rdevice ||
-	    info->xlo_inode != info64->xlo_inode ||
-	    info->xlo_offset != info64->xlo_offset)
-		return -EOVERFLOW;
-
-	return 0;
-}
-
-static int
-xloop_set_status_old(struct xloop_device *xlo, const struct xloop_info __user *arg)
-{
-	struct xloop_info info;
-	struct xloop_info64 info64;
-
-	if (copy_from_user(&info, arg, sizeof(struct xloop_info)))
-		return -EFAULT;
-	xloop_info64_from_old(&info, &info64);
-	return xloop_set_status(xlo, &info64);
-}
-
-static int
-xloop_set_status64(struct xloop_device *xlo, const struct xloop_info64 __user *arg)
-{
-	struct xloop_info64 info64;
-
-	if (copy_from_user(&info64, arg, sizeof(struct xloop_info64)))
-		return -EFAULT;
-	return xloop_set_status(xlo, &info64);
-}
-
-static int
-xloop_get_status_old(struct xloop_device *xlo, struct xloop_info __user *arg)
-{
-	struct xloop_info info;
-	struct xloop_info64 info64;
-	int err;
-
-	if (!arg)
-		return -EINVAL;
-	err = xloop_get_status(xlo, &info64);
-	if (!err)
-		err = xloop_info64_to_old(&info64, &info);
-	if (!err && copy_to_user(arg, &info, sizeof(info)))
-		err = -EFAULT;
-
-	return err;
-}
-
-static int
-xloop_get_status64(struct xloop_device *xlo, struct xloop_info64 __user *arg)
-{
-	struct xloop_info64 info64;
-	int err;
-
-	if (!arg)
-		return -EINVAL;
-	err = xloop_get_status(xlo, &info64);
-	if (!err && copy_to_user(arg, &info64, sizeof(info64)))
-		err = -EFAULT;
-
-	return err;
-}
-
-static int xloop_set_capacity(struct xloop_device *xlo)
-{
-	loff_t size;
-
-	if (unlikely(xlo->xlo_state != Xlo_bound))
-		return -ENXIO;
-
-	size = get_xloop_size(xlo, xlo->xlo_backing_file);
-	xloop_set_size(xlo, size);
-
-	return 0;
-}
-
-static int xloop_set_dio(struct xloop_device *xlo, unsigned long arg)
-{
-	int error = -ENXIO;
-
-	if (xlo->xlo_state != Xlo_bound)
-		goto out;
-
-	__xloop_update_dio(xlo, !!arg);
-	if (xlo->use_dio == !!arg)
-		return 0;
-	error = -EINVAL;
- out:
-	return error;
-}
-
-static int xloop_set_block_size(struct xloop_device *xlo, unsigned long arg)
-{
-	int err = 0;
-
-	if (xlo->xlo_state != Xlo_bound)
-		return -ENXIO;
-
-	err = blk_validate_block_size(arg);
-	if (err)
-		return err;
-
-	if (xlo->xlo_queue->limits.logical_block_size == arg)
-		return 0;
-
-	sync_blockdev(xlo->xlo_device);
-	invalidate_bdev(xlo->xlo_device);
-
-	blk_mq_freeze_queue(xlo->xlo_queue);
-
-	/* invalidate_bdev should have truncated all the pages */
-	if (xlo->xlo_device->bd_inode->i_mapping->nrpages) {
-		err = -EAGAIN;
-		dev_warn(xloop_device_to_dev(xlo),
-			"xloop%d (%s) has still dirty pages (nrpages=%lu)\n",
-			xlo->xlo_number, xlo->xlo_file_name,
-			xlo->xlo_device->bd_inode->i_mapping->nrpages);
-		goto out_unfreeze;
-	}
-
-	blk_queue_logical_block_size(xlo->xlo_queue, arg);
-	blk_queue_physical_block_size(xlo->xlo_queue, arg);
-	blk_queue_io_min(xlo->xlo_queue, arg);
-	xloop_update_dio(xlo);
-out_unfreeze:
-	blk_mq_unfreeze_queue(xlo->xlo_queue);
-
-	return err;
-}
-
-static int xlo_simple_ioctl(struct xloop_device *xlo, unsigned int cmd,
-			   unsigned long arg)
-{
-	int err;
-
-	err = mutex_lock_killable(&xlo->xlo_mutex);
-	if (err)
-		return err;
-	switch (cmd) {
-	case XLOOP_SET_CAPACITY:
-		err = xloop_set_capacity(xlo);
-		break;
-	case XLOOP_SET_DIRECT_IO:
-		err = xloop_set_dio(xlo, arg);
-		break;
-	case XLOOP_SET_BLOCK_SIZE:
-		err = xloop_set_block_size(xlo, arg);
-		break;
-	default:
-		err = xlo->ioctl ? xlo->ioctl(xlo, cmd, arg) : -EINVAL;
-	}
-	mutex_unlock(&xlo->xlo_mutex);
-	return err;
-}
-
-static int xlo_ioctl(struct block_device *bdev, fmode_t mode,
-	unsigned int cmd, unsigned long arg)
-{
-	struct xloop_device *xlo = bdev->bd_disk->private_data;
-	void __user *argp = (void __user *) arg;
-	int err;
-
-	switch (cmd) {
-	case XLOOP_SET_FD: {
-		/*
-		 * Legacy case - pass in a zeroed out struct xloop_config with
-		 * only the file descriptor set , which corresponds with the
-		 * default parameters we'd have used otherwise.
-		 */
-		struct xloop_config config;
-
-		memset(&config, 0, sizeof(config));
-		config.fd = arg;
-
-		return xloop_configure(xlo, mode, bdev, &config);
-	}
-	case XLOOP_CONFIGURE: {
-		struct xloop_config config;
-
-		if (copy_from_user(&config, argp, sizeof(config)))
-			return -EFAULT;
-
-		return xloop_configure(xlo, mode, bdev, &config);
-	}
-	case XLOOP_CHANGE_FD:
-		return xloop_change_fd(xlo, bdev, arg);
-	case XLOOP_CLR_FD:
-		return xloop_clr_fd(xlo);
-	case XLOOP_SET_STATUS:
-		err = -EPERM;
-		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
-			err = xloop_set_status_old(xlo, argp);
-		break;
-	case XLOOP_GET_STATUS:
-		return xloop_get_status_old(xlo, argp);
-	case XLOOP_SET_STATUS64:
-		err = -EPERM;
-		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
-			err = xloop_set_status64(xlo, argp);
-		break;
-	case XLOOP_GET_STATUS64:
-		return xloop_get_status64(xlo, argp);
-	case XLOOP_SET_CAPACITY:
-	case XLOOP_SET_DIRECT_IO:
-	case XLOOP_SET_BLOCK_SIZE:
-		if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
-			return -EPERM;
-		fallthrough;
-	default:
-		err = xlo_simple_ioctl(xlo, cmd, arg);
-		break;
-	}
-
-	return err;
-}
-
-#ifdef CONFIG_COMPAT
-struct compat_xloop_info {
-	compat_int_t	xlo_number;      /* ioctl r/o */
-	compat_dev_t	xlo_device;      /* ioctl r/o */
-	compat_ulong_t	xlo_inode;       /* ioctl r/o */
-	compat_dev_t	xlo_rdevice;     /* ioctl r/o */
-	compat_int_t	xlo_offset;
-	compat_int_t	xlo_encrypt_type;
-	compat_int_t	xlo_encrypt_key_size;    /* ioctl w/o */
-	compat_int_t	xlo_flags;       /* ioctl r/o */
-	char		xlo_name[XLO_NAME_SIZE];
-	unsigned char	xlo_encrypt_key[XLO_KEY_SIZE]; /* ioctl w/o */
-	compat_ulong_t	xlo_init[2];
-	char		reserved[4];
-};
-
-/*
- * Transfer 32-bit compatibility structure in userspace to 64-bit xloop info
- * - noinlined to reduce stack space usage in main part of driver
- */
-static noinline int
-xloop_info64_from_compat(const struct compat_xloop_info __user *arg,
-			struct xloop_info64 *info64)
-{
-	struct compat_xloop_info info;
-
-	if (copy_from_user(&info, arg, sizeof(info)))
-		return -EFAULT;
-
-	memset(info64, 0, sizeof(*info64));
-	info64->xlo_number = info.xlo_number;
-	info64->xlo_device = info.xlo_device;
-	info64->xlo_inode = info.xlo_inode;
-	info64->xlo_rdevice = info.xlo_rdevice;
-	info64->xlo_offset = info.xlo_offset;
-	info64->xlo_sizelimit = 0;
-	info64->xlo_encrypt_type = info.xlo_encrypt_type;
-	info64->xlo_encrypt_key_size = info.xlo_encrypt_key_size;
-	info64->xlo_flags = info.xlo_flags;
-	info64->xlo_init[0] = info.xlo_init[0];
-	info64->xlo_init[1] = info.xlo_init[1];
-	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
-		memcpy(info64->xlo_crypt_name, info.xlo_name, XLO_NAME_SIZE);
-	else
-		memcpy(info64->xlo_file_name, info.xlo_name, XLO_NAME_SIZE);
-	memcpy(info64->xlo_encrypt_key, info.xlo_encrypt_key, XLO_KEY_SIZE);
-	return 0;
-}
-
-/*
- * Transfer 64-bit xloop info to 32-bit compatibility structure in userspace
- * - noinlined to reduce stack space usage in main part of driver
- */
-static noinline int
-xloop_info64_to_compat(const struct xloop_info64 *info64,
-		      struct compat_xloop_info __user *arg)
-{
-	struct compat_xloop_info info;
-
-	memset(&info, 0, sizeof(info));
-	info.xlo_number = info64->xlo_number;
-	info.xlo_device = info64->xlo_device;
-	info.xlo_inode = info64->xlo_inode;
-	info.xlo_rdevice = info64->xlo_rdevice;
-	info.xlo_offset = info64->xlo_offset;
-	info.xlo_encrypt_type = info64->xlo_encrypt_type;
-	info.xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
-	info.xlo_flags = info64->xlo_flags;
-	info.xlo_init[0] = info64->xlo_init[0];
-	info.xlo_init[1] = info64->xlo_init[1];
-	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
-		memcpy(info.xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
-	else
-		memcpy(info.xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
-	memcpy(info.xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
-
-	/* error in case values were truncated */
-	if (info.xlo_device != info64->xlo_device ||
-	    info.xlo_rdevice != info64->xlo_rdevice ||
-	    info.xlo_inode != info64->xlo_inode ||
-	    info.xlo_offset != info64->xlo_offset ||
-	    info.xlo_init[0] != info64->xlo_init[0] ||
-	    info.xlo_init[1] != info64->xlo_init[1])
-		return -EOVERFLOW;
-
-	if (copy_to_user(arg, &info, sizeof(info)))
-		return -EFAULT;
-	return 0;
-}
-
-static int
-xloop_set_status_compat(struct xloop_device *xlo,
-		       const struct compat_xloop_info __user *arg)
-{
-	struct xloop_info64 info64;
-	int ret;
-
-	ret = xloop_info64_from_compat(arg, &info64);
-	if (ret < 0)
-		return ret;
-	return xloop_set_status(xlo, &info64);
-}
-
-static int
-xloop_get_status_compat(struct xloop_device *xlo,
-		       struct compat_xloop_info __user *arg)
-{
-	struct xloop_info64 info64;
-	int err;
-
-	if (!arg)
-		return -EINVAL;
-	err = xloop_get_status(xlo, &info64);
-	if (!err)
-		err = xloop_info64_to_compat(&info64, arg);
-	return err;
-}
-
-static int xlo_compat_ioctl(struct block_device *bdev, fmode_t mode,
-			   unsigned int cmd, unsigned long arg)
-{
-	struct xloop_device *xlo = bdev->bd_disk->private_data;
-	int err;
-
-	switch (cmd) {
-	case XLOOP_SET_STATUS:
-		err = xloop_set_status_compat(xlo,
-			     (const struct compat_xloop_info __user *)arg);
-		break;
-	case XLOOP_GET_STATUS:
-		err = xloop_get_status_compat(xlo,
-				     (struct compat_xloop_info __user *)arg);
-		break;
-	case XLOOP_SET_CAPACITY:
-	case XLOOP_CLR_FD:
-	case XLOOP_GET_STATUS64:
-	case XLOOP_SET_STATUS64:
-	case XLOOP_CONFIGURE:
-		arg = (unsigned long) compat_ptr(arg);
-		fallthrough;
-	case XLOOP_SET_FD:
-	case XLOOP_CHANGE_FD:
-	case XLOOP_SET_BLOCK_SIZE:
-	case XLOOP_SET_DIRECT_IO:
-		err = xlo_ioctl(bdev, mode, cmd, arg);
-		break;
-	default:
-		err = -ENOIOCTLCMD;
-		break;
-	}
-	return err;
-}
-#endif
-
-static int xlo_open(struct block_device *bdev, fmode_t mode)
-{
-	struct xloop_device *xlo = bdev->bd_disk->private_data;
-	int err;
-
-	err = mutex_lock_killable(&xlo->xlo_mutex);
-	if (err)
-		return err;
-	if (xlo->xlo_state == Xlo_deleting)
-		err = -ENXIO;
-	else
-		atomic_inc(&xlo->xlo_refcnt);
-	mutex_unlock(&xlo->xlo_mutex);
-	return err;
-}
-
-static void xlo_release(struct gendisk *disk, fmode_t mode)
-{
-	struct xloop_device *xlo = disk->private_data;
-
-	mutex_lock(&xlo->xlo_mutex);
-	if (atomic_dec_return(&xlo->xlo_refcnt))
-		goto out_unlock;
-
-	if (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR) {
-		if (xlo->xlo_state != Xlo_bound)
-			goto out_unlock;
-		xlo->xlo_state = Xlo_rundown;
-		mutex_unlock(&xlo->xlo_mutex);
-		/*
-		 * In autoclear mode, stop the xloop thread
-		 * and remove configuration after last close.
-		 */
-		__xloop_clr_fd(xlo, true);
-		return;
-	} else if (xlo->xlo_state == Xlo_bound) {
-		/*
-		 * Otherwise keep thread (if running) and config,
-		 * but flush possible ongoing bios in thread.
-		 */
-		blk_mq_freeze_queue(xlo->xlo_queue);
-		blk_mq_unfreeze_queue(xlo->xlo_queue);
-	}
-
-out_unlock:
-	mutex_unlock(&xlo->xlo_mutex);
-}
-
-static const struct block_device_operations xlo_fops = {
-	.owner =	THIS_MODULE,
-	.open =		xlo_open,
-	.release =	xlo_release,
-	.ioctl =	xlo_ioctl,
-#ifdef CONFIG_COMPAT
-	.compat_ioctl =	xlo_compat_ioctl,
-#endif
-};
-
-/*
- * And now the modules code and kernel interface.
- */
-static int max_xloop;
-module_param(max_xloop, int, 0444);
-MODULE_PARM_DESC(max_xloop, "Maximum number of xloop devices");
-module_param(max_part, int, 0444);
-MODULE_PARM_DESC(max_part, "Maximum number of partitions per xloop device");
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Manuel Bentele <development@manuel-bentele.de>");
-MODULE_VERSION(XLOOP_VERSION);
-MODULE_ALIAS_BLOCKDEV_MAJOR(XLOOP_MAJOR);
-
-int xloop_register_transfer(struct xloop_func_table *funcs)
-{
-	unsigned int n = funcs->number;
-
-	if (n >= MAX_XLO_CRYPT || xfer_funcs[n])
-		return -EINVAL;
-	xfer_funcs[n] = funcs;
-	return 0;
-}
-EXPORT_SYMBOL(xloop_register_transfer);
-
-int xloop_unregister_transfer(int number)
-{
-	unsigned int n = number;
-	struct xloop_func_table *xfer = xfer_funcs[n];
-
-	if (n == 0 || n >= MAX_XLO_CRYPT || xfer == NULL)
-		return -EINVAL;
-	/*
-	 * This function is called from only cleanup_cryptoxloop().
-	 * Given that each xloop device that has a transfer enabled holds a
-	 * reference to the module implementing it we should never get here
-	 * with a transfer that is set (unless forced module unloading is
-	 * requested). Thus, check module's refcount and warn if this is
-	 * not a clean unloading.
-	 */
-#ifdef CONFIG_MODULE_UNLOAD
-	if (xfer->owner && module_refcount(xfer->owner) != -1)
-		pr_err("Danger! Unregistering an in use transfer function.\n");
-#endif
-
-	xfer_funcs[n] = NULL;
-	return 0;
-}
-EXPORT_SYMBOL(xloop_unregister_transfer);
-
-static blk_status_t xloop_queue_rq(struct blk_mq_hw_ctx *hctx,
-		const struct blk_mq_queue_data *bd)
-{
-	struct request *rq = bd->rq;
-	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
-	struct xloop_device *xlo = rq->q->queuedata;
-
-	blk_mq_start_request(rq);
-
-	if (xlo->xlo_state != Xlo_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 = xlo->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
-	xloop_queue_work(xlo, cmd);
-
-	return BLK_STS_OK;
-}
-
-static void xloop_handle_cmd(struct xloop_cmd *cmd)
-{
-	struct request *rq = blk_mq_rq_from_pdu(cmd);
-	const bool write = op_is_write(req_op(rq));
-	struct xloop_device *xlo = rq->q->queuedata;
-	int ret = 0;
-	struct mem_cgroup *old_memcg = NULL;
-
-	if (write && (xlo->xlo_flags & XLO_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(xlo, 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 xloop_set_timer(struct xloop_device *xlo)
-{
-	timer_reduce(&xlo->timer, jiffies + XLOOP_IDLE_WORKER_TIMEOUT);
-}
-
-static void xloop_process_work(struct xloop_worker *worker,
-			struct list_head *cmd_list, struct xloop_device *xlo)
-{
-	int orig_flags = current->flags;
-	struct xloop_cmd *cmd;
-
-	current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
-	spin_lock_irq(&xlo->xlo_work_lock);
-	while (!list_empty(cmd_list)) {
-		cmd = container_of(
-			cmd_list->next, struct xloop_cmd, list_entry);
-		list_del(cmd_list->next);
-		spin_unlock_irq(&xlo->xlo_work_lock);
-
-		xloop_handle_cmd(cmd);
-		cond_resched();
-
-		spin_lock_irq(&xlo->xlo_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, &xlo->idle_worker_list);
-		xloop_set_timer(xlo);
-	}
-	spin_unlock_irq(&xlo->xlo_work_lock);
-	current->flags = orig_flags;
-}
-
-static void xloop_workfn(struct work_struct *work)
-{
-	struct xloop_worker *worker =
-		container_of(work, struct xloop_worker, work);
-	xloop_process_work(worker, &worker->cmd_list, worker->xlo);
-}
-
-static void xloop_rootcg_workfn(struct work_struct *work)
-{
-	struct xloop_device *xlo =
-		container_of(work, struct xloop_device, rootcg_work);
-	xloop_process_work(NULL, &xlo->rootcg_cmd_list, xlo);
-}
-
-static void xloop_free_idle_workers(struct timer_list *timer)
-{
-	struct xloop_device *xlo = container_of(timer, struct xloop_device, timer);
-	struct xloop_worker *pos, *worker;
-
-	spin_lock_irq(&xlo->xlo_work_lock);
-	list_for_each_entry_safe(worker, pos, &xlo->idle_worker_list,
-				idle_list) {
-		if (time_is_after_jiffies(worker->last_ran_at +
-						XLOOP_IDLE_WORKER_TIMEOUT))
-			break;
-		list_del(&worker->idle_list);
-		rb_erase(&worker->rb_node, &xlo->worker_tree);
-		css_put(worker->blkcg_css);
-		kfree(worker);
-	}
-	if (!list_empty(&xlo->idle_worker_list))
-		xloop_set_timer(xlo);
-	spin_unlock_irq(&xlo->xlo_work_lock);
-}
-
-static const struct blk_mq_ops xloop_mq_ops = {
-	.queue_rq       = xloop_queue_rq,
-	.complete	= xlo_complete_rq,
-};
-
-static struct dentry *xloop_dbgfs_dir;
-
-static int xloop_add(int i)
-{
-	struct xloop_device *xlo;
-	struct gendisk *disk;
-	int err;
-
-	err = -ENOMEM;
-	xlo = kzalloc(sizeof(*xlo), GFP_KERNEL);
-	if (!xlo)
-		goto out;
-	xlo->xlo_state = Xlo_unbound;
-
-	err = mutex_lock_killable(&xloop_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(&xloop_index_idr, xlo, i, i + 1, GFP_KERNEL);
-		if (err == -ENOSPC)
-			err = -EEXIST;
-	} else {
-		err = idr_alloc(&xloop_index_idr, xlo, 0, 0, GFP_KERNEL);
-	}
-	mutex_unlock(&xloop_ctl_mutex);
-	if (err < 0)
-		goto out_free_dev;
-	i = err;
-
-	err = -ENOMEM;
-	xlo->tag_set.ops = &xloop_mq_ops;
-	xlo->tag_set.nr_hw_queues = 1;
-	xlo->tag_set.queue_depth = 128;
-	xlo->tag_set.numa_node = NUMA_NO_NODE;
-	xlo->tag_set.cmd_size = sizeof(struct xloop_cmd);
-	xlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
-		BLK_MQ_F_NO_SCHED_BY_DEFAULT;
-	xlo->tag_set.driver_data = xlo;
-
-	err = blk_mq_alloc_tag_set(&xlo->tag_set);
-	if (err)
-		goto out_free_idr;
-
-	disk = xlo->xlo_disk = blk_mq_alloc_disk(&xlo->tag_set, xlo);
-	if (IS_ERR(disk)) {
-		err = PTR_ERR(disk);
-		goto out_cleanup_tags;
-	}
-	xlo->xlo_queue = xlo->xlo_disk->queue;
-
-	blk_queue_max_hw_sectors(xlo->xlo_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, xlo->xlo_queue);
-
-	err = -ENOMEM;
-	xlo->xlo_fmt = xloop_file_fmt_alloc();
-	if (!xlo->xlo_fmt)
-		goto out_cleanup_disk;
-
-	xloop_file_fmt_set_xlo(xlo->xlo_fmt, xlo);
-
-	/*
-	 * 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 xloop device numbers will continue
-	 * to match the xloop minors, regardless of the number of partitions
-	 * used.
-	 *
-	 * If max_part is given, partition scanning is globally enabled for
-	 * all xloop devices. The minors for the main xloop devices will be
-	 * multiples of max_part.
-	 *
-	 * Note: Global-for-all-devices, set-only-at-init, read-only module
-	 * parameteters like 'max_xloop' 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(&xlo->xlo_refcnt, 0);
-	mutex_init(&xlo->xlo_mutex);
-	xlo->xlo_number = i;
-	spin_lock_init(&xlo->xlo_lock);
-	spin_lock_init(&xlo->xlo_work_lock);
-	disk->major = XLOOP_MAJOR;
-	disk->first_minor = i << part_shift;
-	disk->minors = 1 << part_shift;
-	disk->fops = &xlo_fops;
-	disk->private_data = xlo;
-	disk->queue = xlo->xlo_queue;
-	disk->events = DISK_EVENT_MEDIA_CHANGE;
-	disk->event_flags = DISK_EVENT_FLAG_UEVENT;
-	sprintf(disk->disk_name, "xloop%d", i);
-	/* Make this xloop device reachable from pathname. */
-	add_disk(disk);
-	/* Show this xloop device. */
-	mutex_lock(&xloop_ctl_mutex);
-	xlo->idr_visible = true;
-	mutex_unlock(&xloop_ctl_mutex);
-
-	/*
-	 * initialize debugfs entries
-	 *
-	 * create for each xloop device a debugfs directory under 'xloop' if
-	 * the 'block' directory exists, otherwise create the loop directory in
-	 * the root directory
-	 */
-#ifdef CONFIG_DEBUG_FS
-	xlo->xlo_dbgfs_dir = debugfs_create_dir(disk->disk_name, xloop_dbgfs_dir);
-
-	if (IS_ERR_OR_NULL(xlo->xlo_dbgfs_dir)) {
-		err = -ENODEV;
-		xlo->xlo_dbgfs_dir = NULL;
-		goto out_free_file_fmt;
-	}
-#endif
-
-	return i;
-
-out_free_file_fmt:
-	xloop_file_fmt_free(xlo->xlo_fmt);
-out_cleanup_disk:
-	blk_cleanup_disk(xlo->xlo_disk);
-out_cleanup_tags:
-	blk_mq_free_tag_set(&xlo->tag_set);
-out_free_idr:
-	mutex_lock(&xloop_ctl_mutex);
-	idr_remove(&xloop_index_idr, i);
-	mutex_unlock(&xloop_ctl_mutex);
-out_free_dev:
-	kfree(xlo);
-out:
-	return err;
-}
-
-static void xloop_remove(struct xloop_device *xlo)
-{
-	xloop_file_fmt_free(xlo->xlo_fmt);
-	debugfs_remove(xlo->xlo_dbgfs_dir);
-	/* Make this xloop device unreachable from pathname. */
-	del_gendisk(xlo->xlo_disk);
-	blk_cleanup_disk(xlo->xlo_disk);
-	blk_mq_free_tag_set(&xlo->tag_set);
-	mutex_lock(&xloop_ctl_mutex);
-	idr_remove(&xloop_index_idr, xlo->xlo_number);
-	mutex_unlock(&xloop_ctl_mutex);
-	/* There is no route which can find this xloop device. */
-	mutex_destroy(&xlo->xlo_mutex);
-	kfree(xlo);
-}
-
-static void xloop_probe(dev_t dev)
-{
-	int idx = MINOR(dev) >> part_shift;
-
-	if (max_xloop && idx >= max_xloop)
-		return;
-	xloop_add(idx);
-}
-
-static int xloop_control_remove(int idx)
-{
-	struct xloop_device *xlo;
-	int ret;
-
-	if (idx < 0) {
-		pr_warn("deleting an unspecified xloop device is not supported.\n");
-		return -EINVAL;
-	}
-
-	/* Hide this xloop device for serialization. */
-	ret = mutex_lock_killable(&xloop_ctl_mutex);
-	if (ret)
-		return ret;
-	xlo = idr_find(&xloop_index_idr, idx);
-	if (!xlo || !xlo->idr_visible)
-		ret = -ENODEV;
-	else
-		xlo->idr_visible = false;
-	mutex_unlock(&xloop_ctl_mutex);
-	if (ret)
-		return ret;
-
-	/* Check whether this xloop device can be removed. */
-	ret = mutex_lock_killable(&xlo->xlo_mutex);
-	if (ret)
-		goto mark_visible;
-	if (xlo->xlo_state != Xlo_unbound ||
-	    atomic_read(&xlo->xlo_refcnt) > 0) {
-		mutex_unlock(&xlo->xlo_mutex);
-		ret = -EBUSY;
-		goto mark_visible;
-	}
-	/* Mark this xloop device no longer open()-able. */
-	xlo->xlo_state = Xlo_deleting;
-	mutex_unlock(&xlo->xlo_mutex);
-
-	xloop_remove(xlo);
-	return 0;
-
-mark_visible:
-	/* Show this xloop device again. */
-	mutex_lock(&xloop_ctl_mutex);
-	xlo->idr_visible = true;
-	mutex_unlock(&xloop_ctl_mutex);
-	return ret;
-}
-
-static int xloop_control_get_free(int idx)
-{
-	struct xloop_device *xlo;
-	int id, ret;
-
-	ret = mutex_lock_killable(&xloop_ctl_mutex);
-	if (ret)
-		return ret;
-	idr_for_each_entry(&xloop_index_idr, xlo, id) {
-		/* Hitting a race results in creating a new xloop device which is harmless. */
-		if (xlo->idr_visible && data_race(xlo->xlo_state) == Xlo_unbound)
-			goto found;
-	}
-	mutex_unlock(&xloop_ctl_mutex);
-	return xloop_add(-1);
-found:
-	mutex_unlock(&xloop_ctl_mutex);
-	return id;
-}
-
-static long xloop_control_ioctl(struct file *file, unsigned int cmd,
-			       unsigned long parm)
-{
-	switch (cmd) {
-	case XLOOP_CTL_ADD:
-		return xloop_add(parm);
-	case XLOOP_CTL_REMOVE:
-		return xloop_control_remove(parm);
-	case XLOOP_CTL_GET_FREE:
-		return xloop_control_get_free(parm);
-	default:
-		return -ENOSYS;
-	}
-}
-
-static const struct file_operations xloop_ctl_fops = {
-	.open		= nonseekable_open,
-	.unlocked_ioctl	= xloop_control_ioctl,
-	.compat_ioctl	= xloop_control_ioctl,
-	.owner		= THIS_MODULE,
-	.llseek		= noop_llseek,
-};
-
-static struct miscdevice xloop_misc = {
-	.minor		= XLOOP_CTRL_MINOR,
-	.name		= "xloop-control",
-	.fops		= &xloop_ctl_fops,
-};
-
-MODULE_ALIAS_MISCDEV(XLOOP_CTRL_MINOR);
-MODULE_ALIAS("devname:xloop-control");
-
-static int __init xloop_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_xloop > 1UL << (MINORBITS - part_shift)) {
-		err = -EINVAL;
-		goto err_out;
-	}
-
-	/*
-	 * If max_xloop is specified, create that many devices upfront.
-	 * This also becomes a hard limit. If max_xloop is not specified,
-	 * create CONFIG_BLK_DEV_XLOOP_MIN_COUNT xloop devices at module
-	 * init time. Loop devices can be requested on-demand with the
-	 * /dev/xloop-control interface, or be instantiated by accessing
-	 * a 'dead' device node.
-	 */
-	if (max_xloop)
-		nr = max_xloop;
-	else
-		nr = CONFIG_BLK_DEV_XLOOP_MIN_COUNT;
-
-	err = misc_register(&xloop_misc);
-	if (err < 0)
-		goto err_out;
-
-
-	if (__register_blkdev(XLOOP_MAJOR, "xloop", xloop_probe)) {
-		err = -EIO;
-		goto misc_out;
-	}
-
-#ifdef CONFIG_DEBUG_FS
-	xloop_dbgfs_dir = debugfs_create_dir("xloop", NULL);
-	if (IS_ERR_OR_NULL(xloop_dbgfs_dir)) {
-		err = -ENODEV;
-		goto blkdev_out;
-	}
-#endif
-
-	/* pre-create number of devices given by config or max_xloop */
-	for (i = 0; i < nr; i++)
-		xloop_add(i);
-
-	pr_info("module in version %s loaded\n", XLOOP_VERSION);
-	return 0;
-
-#ifdef CONFIG_DEBUG_FS
-blkdev_out:
-	unregister_blkdev(XLOOP_MAJOR, "xloop");
-#endif
-misc_out:
-	misc_deregister(&xloop_misc);
-err_out:
-	return err;
-}
-
-static void __exit xloop_exit(void)
-{
-	struct xloop_device *xlo;
-	int id;
-
-	unregister_blkdev(XLOOP_MAJOR, "xloop");
-	misc_deregister(&xloop_misc);
-
-	/*
-	 * There is no need to use xloop_ctl_mutex here, for nobody else can
-	 * access xloop_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(&xloop_index_idr, xlo, id)
-		xloop_remove(xlo);
-
-	idr_destroy(&xloop_index_idr);
-
-#ifdef CONFIG_DEBUG_FS
-	debugfs_remove(xloop_dbgfs_dir);
-#endif
-
-	pr_info("exit module\n");
-}
-
-module_init(xloop_init);
-module_exit(xloop_exit);
-
-#ifndef MODULE
-static int __init max_xloop_setup(char *str)
-{
-	max_xloop = simple_strtol(str, NULL, 0);
-	return 1;
-}
-
-__setup("max_xloop=", max_xloop_setup);
+#include "xloop_main_5.15.c"
 #endif
diff --git a/src/kernel/xloop_main.h b/src/kernel/xloop_main.h
index 4126460..c1cc919 100644
--- a/src/kernel/xloop_main.h
+++ b/src/kernel/xloop_main.h
@@ -1,109 +1,7 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * loop_main.h
- *
- * 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.
- */
-#ifndef _LINUX_XLOOP_H
-#define _LINUX_XLOOP_H
-
-#include <linux/bio.h>
-#include <linux/blkdev.h>
-#include <linux/blk-mq.h>
-#include <linux/spinlock.h>
-#include <linux/mutex.h>
-#include "uapi_xloop.h"
-#ifdef CONFIG_DEBUG_FS
-#include <linux/debugfs.h>
-#endif
-
-#include "xloop_file_fmt.h"
-
-/* Possible states of device */
-enum {
-	Xlo_unbound,
-	Xlo_bound,
-	Xlo_rundown,
-	Xlo_deleting,
-};
-
-struct xloop_func_table;
-
-struct xloop_device {
-	int                     xlo_number;
-	atomic_t                xlo_refcnt;
-	loff_t                  xlo_offset;
-	loff_t                  xlo_sizelimit;
-	int                     xlo_flags;
-	int                     (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned raw_off, struct page *xloop_page, unsigned xloop_off, int size, sector_t real_block);
-	char                    xlo_file_name[XLO_NAME_SIZE];
-	char                    xlo_crypt_name[XLO_NAME_SIZE];
-	char                    xlo_encrypt_key[XLO_KEY_SIZE];
-	int                     xlo_encrypt_key_size;
-	struct xloop_func_table *xlo_encryption;
-	__u32                   xlo_init[2];
-	kuid_t                  xlo_key_owner;	/* Who set the key */
-	int                     (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
-
-	struct xloop_file_fmt   *xlo_fmt;
-
-	struct file             *xlo_backing_file;
-	struct block_device     *xlo_device;
-	void                    *key_data;
-
-	gfp_t                   old_gfp_mask;
-
-	spinlock_t              xlo_lock;
-	int                     xlo_state;
-	spinlock_t              xlo_work_lock;
-	struct workqueue_struct *workqueue;
-	struct work_struct      rootcg_work;
-	struct list_head        rootcg_cmd_list;
-	struct list_head        idle_worker_list;
-	struct rb_root          worker_tree;
-	struct timer_list       timer;
-	bool                    use_dio;
-	bool                    sysfs_inited;
-
-	struct request_queue    *xlo_queue;
-	struct blk_mq_tag_set   tag_set;
-	struct gendisk          *xlo_disk;
-	struct mutex            xlo_mutex;
-	bool                    idr_visible;
-
-#ifdef CONFIG_DEBUG_FS
-	struct dentry           *xlo_dbgfs_dir;
-#endif
-};
-
-struct xloop_cmd {
-	struct list_head           list_entry;
-	bool                       use_aio;  /* use AIO interface to handle I/O */
-	atomic_t                   ref;  /* only for aio */
-	long                       ret;
-	struct kiocb               iocb;
-	struct bio_vec             *bvec;
-	struct cgroup_subsys_state *blkcg_css;
-	struct cgroup_subsys_state *memcg_css;
-};
-
-/* Support for loadable transfer modules */
-struct xloop_func_table {
-	int           number;  /* filter type */
-	int           (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned raw_off, struct page *xloop_page, unsigned xloop_off, int size, sector_t real_block);
-	int           (*init)(struct xloop_device *xlo, const struct xloop_info64 *info);
-	/* release is called from xloop_unregister_transfer or clr_fd */
-	int           (*release)(struct xloop_device *xlo);
-	int           (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
-	struct module *owner;
-};
-
-extern inline struct device *xloop_device_to_dev(struct xloop_device *xlo);
-
-int xloop_register_transfer(struct xloop_func_table *funcs);
-int xloop_unregister_transfer(int number);
+#include <linux/version.h>
 
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+#include "xloop_main_4.18.h"
+#else
+#include "xloop_main_5.15.h"
 #endif
diff --git a/src/kernel/xloop_main_4.18.c b/src/kernel/xloop_main_4.18.c
new file mode 100644
index 0000000..9fe0c70
--- /dev/null
+++ b/src/kernel/xloop_main_4.18.c
@@ -0,0 +1,2212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * xloop_main.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_xloop_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 xloop devices now dynamic via max_xloop module parameter.
+ * Russell Kroll <rkroll@exploits.org> 19990701
+ *
+ * Maximum number of xloop devices when compiled-in now selectable by passing
+ * max_xloop=<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 xloop 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
+ *
+ * Support for using file formats.
+ * Manuel Bentele <development@manuel-bentele.de>, 2019
+ *
+ * Still To Fix:
+ * - Advisory locking is ignored here.
+ * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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 <linux/version.h>
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
+
+#include <xloop/version.h>
+
+#include "xloop_file_fmt.h"
+#include "xloop_main.h"
+
+#include <linux/uaccess.h>
+
+/* define RHEL_CHECK_VERSION macro to check CentOS version */
+#if defined(RHEL_RELEASE_CODE) && defined(RHEL_RELEASE_VERSION)
+#define RHEL_CHECK_VERSION(CONDITION) (CONDITION)
+#else
+#define RHEL_CHECK_VERSION(CONDITION) (0)
+#endif
+
+static DEFINE_IDR(xloop_index_idr);
+static DEFINE_MUTEX(xloop_ctl_mutex);
+
+static int max_part;
+static int part_shift;
+
+struct device *xloop_device_to_dev(struct xloop_device *xlo)
+{
+	return disk_to_dev(xlo->xlo_disk);
+}
+EXPORT_SYMBOL(xloop_device_to_dev);
+
+static int transfer_xor(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned int raw_off,
+			struct page *xloop_page, unsigned int xloop_off, int size, sector_t real_block)
+{
+	char *raw_buf = kmap_atomic(raw_page) + raw_off;
+	char *xloop_buf = kmap_atomic(xloop_page) + xloop_off;
+	char *in, *out, *key;
+	int i, keysize;
+
+	if (cmd == READ) {
+		in = raw_buf;
+		out = xloop_buf;
+	} else {
+		in = xloop_buf;
+		out = raw_buf;
+	}
+
+	key = xlo->xlo_encrypt_key;
+	keysize = xlo->xlo_encrypt_key_size;
+	for (i = 0; i < size; i++)
+		*out++ = *in++ ^ key[(i & 511) % keysize];
+
+	kunmap_atomic(xloop_buf);
+	kunmap_atomic(raw_buf);
+	cond_resched();
+	return 0;
+}
+
+static int xor_init(struct xloop_device *xlo, const struct xloop_info64 *info)
+{
+	if (unlikely(info->xlo_encrypt_key_size <= 0))
+		return -EINVAL;
+	return 0;
+}
+
+static struct xloop_func_table none_funcs = {
+	.number = XLO_CRYPT_NONE,
+};
+
+static struct xloop_func_table xor_funcs = { .number = XLO_CRYPT_XOR, .transfer = transfer_xor, .init = xor_init };
+
+/* xfer_funcs[0] is special - its release function is never called */
+static struct xloop_func_table *xfer_funcs[MAX_XLO_CRYPT] = { &none_funcs, &xor_funcs };
+
+static loff_t get_xloop_size(struct xloop_device *xlo, struct file *file)
+{
+	return xloop_file_fmt_sector_size(xlo->xlo_fmt, file, xlo->xlo_offset, xlo->xlo_sizelimit);
+}
+
+static void __xloop_update_dio(struct xloop_device *xlo, bool dio)
+{
+	struct file *file = xlo->xlo_backing_file;
+	struct address_space *mapping = file->f_mapping;
+	struct inode *inode = mapping->host;
+	unsigned short sb_bsize = 0;
+	unsigned int 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 xlo_offset is aligned with the
+	 * logical I/O size of backing device, and the logical block
+	 * size of xloop is bigger than the backing device's and the xloop
+	 * 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(xlo->xlo_queue) >= sb_bsize && !(xlo->xlo_offset & dio_align) &&
+		    mapping->a_ops->direct_IO && !xlo->transfer)
+			use_dio = true;
+		else
+			use_dio = false;
+	} else {
+		use_dio = false;
+	}
+
+	if (xlo->use_dio == use_dio)
+		return;
+
+	/* flush dirty pages before changing direct IO */
+	xloop_file_fmt_flush(xlo->xlo_fmt);
+
+	/*
+	 * The flag of XLO_FLAGS_DIRECT_IO is handled similarly with
+	 * XLO_FLAGS_READ_ONLY, both are set from kernel, and losetup
+	 * will get updated by ioctl(XLOOP_GET_STATUS)
+	 */
+	if (xlo->xlo_state == Xlo_bound)
+		blk_mq_freeze_queue(xlo->xlo_queue);
+	xlo->use_dio = use_dio;
+	if (use_dio) {
+		blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
+		xlo->xlo_flags |= XLO_FLAGS_DIRECT_IO;
+	} else {
+		blk_queue_flag_set(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
+		xlo->xlo_flags &= ~XLO_FLAGS_DIRECT_IO;
+	}
+	if (xlo->xlo_state == Xlo_bound)
+		blk_mq_unfreeze_queue(xlo->xlo_queue);
+}
+
+/**
+ * xloop_validate_block_size() - validates the passed in block size
+ * @bsize: size to validate
+ */
+static int xloop_validate_block_size(unsigned short bsize)
+{
+	if (bsize < 512 || bsize > PAGE_SIZE || !is_power_of_2(bsize))
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * xloop_set_size() - sets device size and notifies userspace
+ * @xlo: struct xloop_device to set the size for
+ * @size: new size of the xloop device
+ *
+ * Callers must validate that the size passed into this function fits into
+ * a sector_t, eg using xloop_validate_size()
+ */
+static void xloop_set_size(struct xloop_device *xlo, loff_t size)
+{
+	struct block_device *bdev = xlo->xlo_device;
+#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 7, 0)
+	sector_t capacity;
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
+	bd_set_nr_sectors(bdev, size);
+#else
+	bd_set_size(bdev, size << SECTOR_SHIFT);
+#endif
+
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
+	if (!set_capacity_revalidate_and_notify(xlo->xlo_disk, size, false))
+		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 7, 0)
+	set_capacity_revalidate_and_notify(xlo->xlo_disk, size, false);
+#else
+	capacity = get_capacity(xlo->xlo_disk);
+	set_capacity(xlo->xlo_disk, size);
+	if (capacity != size && capacity != 0 && size != 0) {
+		char *envp[] = { "RESIZE=1", NULL };
+
+		kobject_uevent_env(&disk_to_dev(xlo->xlo_disk)->kobj, KOBJ_CHANGE, envp);
+	}
+#endif
+}
+
+static void xlo_complete_rq(struct request *rq)
+{
+	struct xloop_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 int do_req_filebacked(struct xloop_device *xlo, struct request *rq)
+{
+	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+
+	/*
+	 * xlo_write_simple and xlo_read_simple should have been covered
+	 * by io submit style function like xlo_rw_aio(), one blocker
+	 * is that xlo_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 xloop_file_fmt_flush(xlo->xlo_fmt);
+	case REQ_OP_WRITE_ZEROES:
+		return xloop_file_fmt_write_zeros(xlo->xlo_fmt, rq);
+	case REQ_OP_DISCARD:
+		return xloop_file_fmt_discard(xlo->xlo_fmt, rq);
+	case REQ_OP_WRITE:
+		if (cmd->use_aio)
+			return xloop_file_fmt_write_aio(xlo->xlo_fmt, rq);
+		else
+			return xloop_file_fmt_write(xlo->xlo_fmt, rq);
+	case REQ_OP_READ:
+		if (cmd->use_aio)
+			return xloop_file_fmt_read_aio(xlo->xlo_fmt, rq);
+		else
+			return xloop_file_fmt_read(xlo->xlo_fmt, rq);
+	default:
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+}
+
+static inline void xloop_update_dio(struct xloop_device *xlo)
+{
+	__xloop_update_dio(xlo, (xlo->xlo_backing_file->f_flags & O_DIRECT) | xlo->use_dio);
+}
+
+static void xloop_reread_partitions(struct xloop_device *xlo, struct block_device *bdev)
+{
+	int rc;
+
+#if (KERNEL_VERSION(5, 5, 0) <= LINUX_VERSION_CODE) ||                                                                 \
+	RHEL_CHECK_VERSION(RHEL_RELEASE_VERSION(8, 3) <= RHEL_RELEASE_CODE)
+	mutex_lock(&bdev->bd_mutex);
+	rc = bdev_disk_changed(bdev, false);
+	mutex_unlock(&bdev->bd_mutex);
+#else
+	rc = blkdev_reread_part(bdev);
+#endif
+	if (rc)
+		dev_warn(xloop_device_to_dev(xlo), "partition scan failed (rc=%d)\n", rc);
+}
+
+static inline int is_xloop_device(struct file *file)
+{
+	struct inode *i = file->f_mapping->host;
+
+	return i && S_ISBLK(i->i_mode) && MAJOR(i->i_rdev) == XLOOP_MAJOR;
+}
+
+static int xloop_validate_file(struct file *file, struct block_device *bdev)
+{
+	struct inode *inode = file->f_mapping->host;
+	struct file *f = file;
+
+	/* Avoid recursion */
+	while (is_xloop_device(f)) {
+		struct xloop_device *l;
+
+		if (f->f_mapping->host->i_bdev == bdev)
+			return -EBADF;
+
+		l = f->f_mapping->host->i_bdev->bd_disk->private_data;
+		if (l->xlo_state != Xlo_bound)
+			return -EINVAL;
+
+		f = l->xlo_backing_file;
+	}
+	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ * xloop_change_fd switched the backing store of a xloopback 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 xloop device is used read-only, and if the
+ * new backing store is the same size and type as the old backing store.
+ */
+static int xloop_change_fd(struct xloop_device *xlo, struct block_device *bdev, unsigned int arg)
+{
+	struct file *file = NULL, *old_file;
+	int error;
+	bool partscan;
+
+	error = mutex_lock_killable(&xloop_ctl_mutex);
+	if (error)
+		return error;
+	error = -ENXIO;
+	if (xlo->xlo_state != Xlo_bound)
+		goto out_err;
+
+	/* the xloop device has to be read-only */
+	error = -EINVAL;
+	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY))
+		goto out_err;
+
+	error = -EBADF;
+	file = fget(arg);
+	if (!file)
+		goto out_err;
+
+	error = xloop_validate_file(file, bdev);
+	if (error)
+		goto out_err;
+
+	old_file = xlo->xlo_backing_file;
+
+	error = -EINVAL;
+
+	/* size of the new backing store needs to be the same */
+	if (get_xloop_size(xlo, file) != get_xloop_size(xlo, old_file))
+		goto out_err;
+
+	/* and ... switch */
+	blk_mq_freeze_queue(xlo->xlo_queue);
+	mapping_set_gfp_mask(old_file->f_mapping, xlo->old_gfp_mask);
+	xlo->xlo_backing_file = file;
+	xlo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
+	mapping_set_gfp_mask(file->f_mapping, xlo->old_gfp_mask & ~(__GFP_IO | __GFP_FS));
+	xloop_update_dio(xlo);
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
+	mutex_unlock(&xloop_ctl_mutex);
+	/*
+	 * We must drop file reference outside of xloop_ctl_mutex as dropping
+	 * the file ref can take bd_mutex which creates circular locking
+	 * dependency.
+	 */
+	fput(old_file);
+	if (partscan)
+		xloop_reread_partitions(xlo, bdev);
+	return 0;
+
+out_err:
+	mutex_unlock(&xloop_ctl_mutex);
+	if (file)
+		fput(file);
+	return error;
+}
+
+/* xloop sysfs attributes */
+
+static ssize_t xloop_attr_show(struct device *dev, char *page, ssize_t (*callback)(struct xloop_device *, char *))
+{
+	struct gendisk *disk = dev_to_disk(dev);
+	struct xloop_device *xlo = disk->private_data;
+
+	return callback(xlo, page);
+}
+
+#define XLOOP_ATTR_RO(_name)                                                                                           \
+	static ssize_t xloop_attr_##_name##_show(struct xloop_device *, char *);                                       \
+	static ssize_t xloop_attr_do_show_##_name(struct device *d, struct device_attribute *attr, char *b)            \
+	{                                                                                                              \
+		return xloop_attr_show(d, b, xloop_attr_##_name##_show);                                               \
+	}                                                                                                              \
+	static struct device_attribute xloop_attr_##_name = __ATTR(_name, 0444, xloop_attr_do_show_##_name, NULL);
+
+static ssize_t xloop_attr_backing_file_show(struct xloop_device *xlo, char *buf)
+{
+	ssize_t ret;
+	char *p = NULL;
+
+	spin_lock_irq(&xlo->xlo_lock);
+	if (xlo->xlo_backing_file)
+		p = file_path(xlo->xlo_backing_file, buf, PAGE_SIZE - 1);
+	spin_unlock_irq(&xlo->xlo_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 xloop_attr_file_fmt_type_show(struct xloop_device *xlo, char *buf)
+{
+	ssize_t len = 0;
+
+	len = xloop_file_fmt_print_type(xlo->xlo_fmt->file_fmt_type, buf);
+	len += sprintf(buf + len, "\n");
+
+	return len;
+}
+
+static ssize_t xloop_attr_offset_show(struct xloop_device *xlo, char *buf)
+{
+	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_offset);
+}
+
+static ssize_t xloop_attr_sizelimit_show(struct xloop_device *xlo, char *buf)
+{
+	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_sizelimit);
+}
+
+static ssize_t xloop_attr_autoclear_show(struct xloop_device *xlo, char *buf)
+{
+	int autoclear = (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR);
+
+	return sprintf(buf, "%s\n", autoclear ? "1" : "0");
+}
+
+static ssize_t xloop_attr_partscan_show(struct xloop_device *xlo, char *buf)
+{
+	int partscan = (xlo->xlo_flags & XLO_FLAGS_PARTSCAN);
+
+	return sprintf(buf, "%s\n", partscan ? "1" : "0");
+}
+
+static ssize_t xloop_attr_dio_show(struct xloop_device *xlo, char *buf)
+{
+	int dio = (xlo->xlo_flags & XLO_FLAGS_DIRECT_IO);
+
+	return sprintf(buf, "%s\n", dio ? "1" : "0");
+}
+
+XLOOP_ATTR_RO(backing_file);
+XLOOP_ATTR_RO(file_fmt_type);
+XLOOP_ATTR_RO(offset);
+XLOOP_ATTR_RO(sizelimit);
+XLOOP_ATTR_RO(autoclear);
+XLOOP_ATTR_RO(partscan);
+XLOOP_ATTR_RO(dio);
+
+static struct attribute *xloop_attrs[] = {
+	&xloop_attr_backing_file.attr, &xloop_attr_file_fmt_type.attr,
+	&xloop_attr_offset.attr,       &xloop_attr_sizelimit.attr,
+	&xloop_attr_autoclear.attr,    &xloop_attr_partscan.attr,
+	&xloop_attr_dio.attr,	       NULL,
+};
+
+static struct attribute_group xloop_attribute_group = {
+	.name  = "xloop",
+	.attrs = xloop_attrs,
+};
+
+static void xloop_sysfs_init(struct xloop_device *xlo)
+{
+	xlo->sysfs_inited = !sysfs_create_group(&disk_to_dev(xlo->xlo_disk)->kobj, &xloop_attribute_group);
+}
+
+static void xloop_sysfs_exit(struct xloop_device *xlo)
+{
+	if (xlo->sysfs_inited)
+		sysfs_remove_group(&disk_to_dev(xlo->xlo_disk)->kobj, &xloop_attribute_group);
+}
+
+static void xloop_config_discard(struct xloop_device *xlo)
+{
+	struct file *file = xlo->xlo_backing_file;
+	struct inode *inode = file->f_mapping->host;
+	struct request_queue *q = xlo->xlo_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 xloop discards result in blkdev_issue_zeroout(),
+	 * not blkdev_issue_discard(). This maintains consistent behavior with
+	 * file-backed xloop devices: discarded regions read back as zero.
+	 */
+	if (S_ISBLK(inode->i_mode) && !xlo->xlo_encrypt_key_size) {
+		struct request_queue *backingq;
+
+		backingq = bdev_get_queue(inode->i_bdev);
+
+		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 || xlo->xlo_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 xloop_unprepare_queue(struct xloop_device *xlo)
+{
+	kthread_flush_worker(&xlo->worker);
+	kthread_stop(xlo->worker_task);
+}
+
+static int xloop_kthread_worker_fn(void *worker_ptr)
+{
+#if (KERNEL_VERSION(5, 8, 0) <= LINUX_VERSION_CODE) ||                                                                 \
+	RHEL_CHECK_VERSION(RHEL_RELEASE_VERSION(8, 4) <= RHEL_RELEASE_CODE)
+	current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
+#else
+	current->flags |= PF_LESS_THROTTLE | PF_MEMALLOC_NOIO;
+#endif
+	return kthread_worker_fn(worker_ptr);
+}
+
+static int xloop_prepare_queue(struct xloop_device *xlo)
+{
+	kthread_init_worker(&xlo->worker);
+	xlo->worker_task = kthread_run(xloop_kthread_worker_fn, &xlo->worker, "xloop%d", xlo->xlo_number);
+	if (IS_ERR(xlo->worker_task))
+		return -ENOMEM;
+	set_user_nice(xlo->worker_task, MIN_NICE);
+	return 0;
+}
+
+static void xloop_update_rotational(struct xloop_device *xlo)
+{
+	struct file *file = xlo->xlo_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 = xlo->xlo_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 xloop_release_xfer(struct xloop_device *xlo)
+{
+	int err = 0;
+	struct xloop_func_table *xfer = xlo->xlo_encryption;
+
+	if (xfer) {
+		if (xfer->release)
+			err = xfer->release(xlo);
+		xlo->transfer = NULL;
+		xlo->xlo_encryption = NULL;
+		module_put(xfer->owner);
+	}
+	return err;
+}
+
+static int xloop_init_xfer(struct xloop_device *xlo, struct xloop_func_table *xfer, const struct xloop_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(xlo, i);
+		if (err)
+			module_put(owner);
+		else
+			xlo->xlo_encryption = xfer;
+	}
+	return err;
+}
+
+/**
+ * xloop_set_status_from_info - configure device from xloop_info
+ * @xlo: struct xloop_device to configure
+ * @info: struct xloop_info64 to configure the device with
+ *
+ * Configures the xloop device parameters according to the passed
+ * in xloop_info64 configuration.
+ */
+static int xloop_set_status_from_info(struct xloop_device *xlo, const struct xloop_info64 *info)
+{
+	int err;
+	struct xloop_func_table *xfer;
+	kuid_t uid = current_uid();
+
+	if ((unsigned int)info->xlo_encrypt_key_size > XLO_KEY_SIZE)
+		return -EINVAL;
+
+	err = xloop_release_xfer(xlo);
+	if (err)
+		return err;
+
+	if (info->xlo_encrypt_type) {
+		unsigned int type = info->xlo_encrypt_type;
+
+		if (type >= MAX_XLO_CRYPT)
+			return -EINVAL;
+		xfer = xfer_funcs[type];
+		if (xfer == NULL)
+			return -EINVAL;
+	} else
+		xfer = NULL;
+
+	err = xloop_init_xfer(xlo, xfer, info);
+	if (err)
+		return err;
+
+	xlo->xlo_offset = info->xlo_offset;
+	xlo->xlo_sizelimit = info->xlo_sizelimit;
+	memcpy(xlo->xlo_file_name, info->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(xlo->xlo_crypt_name, info->xlo_crypt_name, XLO_NAME_SIZE);
+	xlo->xlo_file_name[XLO_NAME_SIZE - 1] = 0;
+	xlo->xlo_crypt_name[XLO_NAME_SIZE - 1] = 0;
+
+	if (!xfer)
+		xfer = &none_funcs;
+	xlo->transfer = xfer->transfer;
+	xlo->ioctl = xfer->ioctl;
+
+	xlo->xlo_flags = info->xlo_flags;
+
+	xlo->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
+	xlo->xlo_init[0] = info->xlo_init[0];
+	xlo->xlo_init[1] = info->xlo_init[1];
+	if (info->xlo_encrypt_key_size) {
+		memcpy(xlo->xlo_encrypt_key, info->xlo_encrypt_key, info->xlo_encrypt_key_size);
+		xlo->xlo_key_owner = uid;
+	}
+
+	return 0;
+}
+
+static int xloop_configure(struct xloop_device *xlo, fmode_t mode, struct block_device *bdev,
+			   const struct xloop_config *config)
+{
+	struct file *file;
+	struct inode *inode;
+	struct address_space *mapping;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
+	struct block_device *claimed_bdev = NULL;
+#endif
+	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)) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0)
+		claimed_bdev = bdev->bd_contains;
+		error = bd_prepare_to_claim(bdev, claimed_bdev, xloop_configure);
+		if (error)
+			goto out_putf;
+#elif LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
+		claimed_bdev = bd_start_claiming(bdev, xloop_configure);
+		if (IS_ERR(claimed_bdev)) {
+			error = PTR_ERR(claimed_bdev);
+			goto out_putf;
+		}
+#else
+		bdgrab(bdev);
+		error = blkdev_get(bdev, mode | FMODE_EXCL, xloop_configure);
+		if (error)
+			goto out_putf;
+#endif
+	}
+
+	error = mutex_lock_killable(&xloop_ctl_mutex);
+	if (error)
+		goto out_bdev;
+
+	error = -EBUSY;
+	if (xlo->xlo_state != Xlo_unbound)
+		goto out_unlock;
+
+	error = xloop_validate_file(file, bdev);
+	if (error)
+		goto out_unlock;
+
+	mapping = file->f_mapping;
+	inode = mapping->host;
+
+	if ((config->info.xlo_flags & ~XLOOP_CONFIGURE_SETTABLE_FLAGS) != 0) {
+		error = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (config->block_size) {
+		error = xloop_validate_block_size(config->block_size);
+		if (error)
+			goto out_unlock;
+	}
+
+	error = xloop_set_status_from_info(xlo, &config->info);
+	if (error)
+		goto out_unlock;
+
+	if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) || !file->f_op->write_iter)
+		xlo->xlo_flags |= XLO_FLAGS_READ_ONLY;
+
+	error = xloop_prepare_queue(xlo);
+	if (error)
+		goto out_unlock;
+
+	set_device_ro(bdev, (xlo->xlo_flags & XLO_FLAGS_READ_ONLY) != 0);
+
+	xlo->use_dio = xlo->xlo_flags & XLO_FLAGS_DIRECT_IO;
+	xlo->xlo_device = bdev;
+	xlo->xlo_backing_file = file;
+	xlo->old_gfp_mask = mapping_gfp_mask(mapping);
+	mapping_set_gfp_mask(mapping, xlo->old_gfp_mask & ~(__GFP_IO | __GFP_FS));
+
+	error = xloop_file_fmt_init(xlo->xlo_fmt, config->info.xlo_file_fmt_type);
+	if (error)
+		goto out_unlock;
+
+	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY) && file->f_op->fsync)
+		blk_queue_write_cache(xlo->xlo_queue, true, false);
+
+	if (config->block_size)
+		bsize = config->block_size;
+	else if ((xlo->xlo_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(xlo->xlo_queue, bsize);
+	blk_queue_physical_block_size(xlo->xlo_queue, bsize);
+	blk_queue_io_min(xlo->xlo_queue, bsize);
+
+	xloop_update_rotational(xlo);
+	xloop_update_dio(xlo);
+	xloop_sysfs_init(xlo);
+
+	size = get_xloop_size(xlo, file);
+	xloop_set_size(xlo, size);
+
+	set_blocksize(bdev, S_ISBLK(inode->i_mode) ? block_size(inode->i_bdev) : PAGE_SIZE);
+
+	xlo->xlo_state = Xlo_bound;
+	if (part_shift)
+		xlo->xlo_flags |= XLO_FLAGS_PARTSCAN;
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
+	if (partscan)
+		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+
+	/* Grab the block_device to prevent its destruction after we
+	 * put /dev/xloopXX inode. Later in __xloop_clr_fd() we bdput(bdev).
+	 */
+	bdgrab(bdev);
+	mutex_unlock(&xloop_ctl_mutex);
+	if (partscan)
+		xloop_reread_partitions(xlo, bdev);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
+	if (claimed_bdev)
+		bd_abort_claiming(bdev, claimed_bdev, xloop_configure);
+#else
+	if (!(mode & FMODE_EXCL))
+		blkdev_put(bdev, mode | FMODE_EXCL);
+#endif
+	return 0;
+
+out_unlock:
+	mutex_unlock(&xloop_ctl_mutex);
+out_bdev:
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
+	if (claimed_bdev)
+		bd_abort_claiming(bdev, claimed_bdev, xloop_configure);
+#else
+	if (!(mode & FMODE_EXCL))
+		blkdev_put(bdev, mode | FMODE_EXCL);
+#endif
+out_putf:
+	fput(file);
+out:
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+	return error;
+}
+
+static int __xloop_clr_fd(struct xloop_device *xlo, bool release)
+{
+	struct file *filp = NULL;
+	gfp_t gfp = xlo->old_gfp_mask;
+	struct block_device *bdev = xlo->xlo_device;
+	int err = 0;
+	bool partscan = false;
+	int xlo_number;
+
+	mutex_lock(&xloop_ctl_mutex);
+	if (WARN_ON_ONCE(xlo->xlo_state != Xlo_rundown)) {
+		err = -ENXIO;
+		goto out_unlock;
+	}
+
+	filp = xlo->xlo_backing_file;
+	if (filp == NULL) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
+	/* freeze request queue during the transition */
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	xloop_file_fmt_exit(xlo->xlo_fmt);
+
+	spin_lock_irq(&xlo->xlo_lock);
+	xlo->xlo_backing_file = NULL;
+	spin_unlock_irq(&xlo->xlo_lock);
+
+	xloop_release_xfer(xlo);
+	xlo->transfer = NULL;
+	xlo->ioctl = NULL;
+	xlo->xlo_device = NULL;
+	xlo->xlo_encryption = NULL;
+	xlo->xlo_offset = 0;
+	xlo->xlo_sizelimit = 0;
+	xlo->xlo_encrypt_key_size = 0;
+	memset(xlo->xlo_encrypt_key, 0, XLO_KEY_SIZE);
+	memset(xlo->xlo_crypt_name, 0, XLO_NAME_SIZE);
+	memset(xlo->xlo_file_name, 0, XLO_NAME_SIZE);
+	blk_queue_logical_block_size(xlo->xlo_queue, 512);
+	blk_queue_physical_block_size(xlo->xlo_queue, 512);
+	blk_queue_io_min(xlo->xlo_queue, 512);
+	if (bdev) {
+		bdput(bdev);
+		invalidate_bdev(bdev);
+		bdev->bd_inode->i_mapping->wb_err = 0;
+	}
+	set_capacity(xlo->xlo_disk, 0);
+	xloop_sysfs_exit(xlo);
+	if (bdev) {
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
+		bd_set_nr_sectors(bdev, 0);
+#else
+		bd_set_size(bdev, 0);
+#endif
+		/* 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(xlo->xlo_queue);
+
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN && bdev;
+	xlo_number = xlo->xlo_number;
+	xloop_unprepare_queue(xlo);
+out_unlock:
+	mutex_unlock(&xloop_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, xlo_refcnt
+		 * must be at least one and it can only become zero when the
+		 * current holder is released.
+		 */
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 5, 0) || RHEL_CHECK_VERSION(RHEL_RELEASE_VERSION(8, 3) <= RHEL_RELEASE_CODE)
+		if (!release)
+			mutex_lock(&bdev->bd_mutex);
+		err = bdev_disk_changed(bdev, false);
+#else
+		err = blkdev_reread_part(bdev);
+#endif
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 5, 0)
+		if (!release)
+			mutex_unlock(&bdev->bd_mutex);
+#endif
+		if (err)
+			dev_warn(xloop_device_to_dev(xlo), "partition scan failed (rc=%d)\n", err);
+
+		/* Device is gone, no point in returning error */
+		err = 0;
+	}
+
+	/*
+	 * xlo->xlo_state is set to Xlo_unbound here after above partscan has
+	 * finished.
+	 *
+	 * There cannot be anybody else entering __xloop_clr_fd() as
+	 * xlo->xlo_backing_file is already cleared and Xlo_rundown state
+	 * protects us from all the other places trying to change the 'xlo'
+	 * device.
+	 */
+	mutex_lock(&xloop_ctl_mutex);
+	xlo->xlo_flags = 0;
+	if (!part_shift)
+		xlo->xlo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+	xlo->xlo_state = Xlo_unbound;
+	mutex_unlock(&xloop_ctl_mutex);
+
+	/*
+	 * Need not hold xloop_ctl_mutex to fput backing file.
+	 * Calling fput holding xloop_ctl_mutex triggers a circular
+	 * lock dependency possibility warning as fput can take
+	 * bd_mutex which is usually taken before xloop_ctl_mutex.
+	 */
+	if (filp)
+		fput(filp);
+	return err;
+}
+
+static int xloop_clr_fd(struct xloop_device *xlo)
+{
+	int err;
+
+	err = mutex_lock_killable(&xloop_ctl_mutex);
+	if (err)
+		return err;
+	if (xlo->xlo_state != Xlo_bound) {
+		mutex_unlock(&xloop_ctl_mutex);
+		return -ENXIO;
+	}
+	/*
+	 * If we've explicitly asked to tear down the xloop 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 xloopback 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(&xlo->xlo_refcnt) > 1) {
+		xlo->xlo_flags |= XLO_FLAGS_AUTOCLEAR;
+		mutex_unlock(&xloop_ctl_mutex);
+		return 0;
+	}
+	xlo->xlo_state = Xlo_rundown;
+	mutex_unlock(&xloop_ctl_mutex);
+
+	return __xloop_clr_fd(xlo, false);
+}
+
+static int xloop_set_status(struct xloop_device *xlo, const struct xloop_info64 *info)
+{
+	int err;
+	struct block_device *bdev;
+	kuid_t uid = current_uid();
+	int prev_xlo_flags;
+	bool partscan = false;
+	bool size_changed = false;
+
+	err = mutex_lock_killable(&xloop_ctl_mutex);
+	if (err)
+		return err;
+	if (xlo->xlo_encrypt_key_size && !uid_eq(xlo->xlo_key_owner, uid) && !capable(CAP_SYS_ADMIN)) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+	if (xlo->xlo_state != Xlo_bound) {
+		err = -ENXIO;
+		goto out_unlock;
+	}
+
+	if (xlo->xlo_offset != info->xlo_offset || xlo->xlo_sizelimit != info->xlo_sizelimit) {
+		size_changed = true;
+		sync_blockdev(xlo->xlo_device);
+		invalidate_bdev(xlo->xlo_device);
+	}
+
+	/* I/O need to be drained during transfer transition */
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	if (size_changed && xlo->xlo_device->bd_inode->i_mapping->nrpages) {
+		/* If any pages were dirtied after invalidate_bdev(), try again */
+		err = -EAGAIN;
+		dev_warn(xloop_device_to_dev(xlo),
+			 "xloop device has still dirty pages (nrpages=%lu)\n",
+			 xlo->xlo_device->bd_inode->i_mapping->nrpages);
+		goto out_unfreeze;
+	}
+
+	prev_xlo_flags = xlo->xlo_flags;
+
+	err = xloop_set_status_from_info(xlo, info);
+	if (err)
+		goto out_unfreeze;
+
+	/* Mask out flags that can't be set using XLOOP_SET_STATUS. */
+	xlo->xlo_flags &= XLOOP_SET_STATUS_SETTABLE_FLAGS;
+	/* For those flags, use the previous values instead */
+	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_SETTABLE_FLAGS;
+	/* For flags that can't be cleared, use previous values too */
+	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_CLEARABLE_FLAGS;
+
+	if (xlo->xlo_fmt->file_fmt_type != info->xlo_file_fmt_type) {
+		/* xloop file format has changed, so change file format driver */
+		err = xloop_file_fmt_change(xlo->xlo_fmt, info->xlo_file_fmt_type);
+		if (err)
+			goto out_unfreeze;
+
+		/* After change of the file format, recalculate the capacity of the xloop device. */
+		size_changed = true;
+	}
+
+	if (size_changed) {
+		loff_t new_size = get_xloop_size(xlo, xlo->xlo_backing_file);
+
+		xloop_set_size(xlo, new_size);
+	}
+
+	xloop_config_discard(xlo);
+
+	/* update dio if xlo_offset or transfer is changed */
+	__xloop_update_dio(xlo, xlo->use_dio);
+
+out_unfreeze:
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+
+	if (!err && (xlo->xlo_flags & XLO_FLAGS_PARTSCAN) && !(prev_xlo_flags & XLO_FLAGS_PARTSCAN)) {
+		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+		bdev = xlo->xlo_device;
+		partscan = true;
+	}
+out_unlock:
+	mutex_unlock(&xloop_ctl_mutex);
+	if (partscan)
+		xloop_reread_partitions(xlo, bdev);
+
+	return err;
+}
+
+static int xloop_get_status(struct xloop_device *xlo, struct xloop_info64 *info)
+{
+	struct path path;
+	struct kstat stat;
+	int ret;
+
+	ret = mutex_lock_killable(&xloop_ctl_mutex);
+	if (ret)
+		return ret;
+	if (xlo->xlo_state != Xlo_bound) {
+		mutex_unlock(&xloop_ctl_mutex);
+		return -ENXIO;
+	}
+
+	memset(info, 0, sizeof(*info));
+	info->xlo_number = xlo->xlo_number;
+	info->xlo_offset = xlo->xlo_offset;
+	info->xlo_sizelimit = xlo->xlo_sizelimit;
+	info->xlo_flags = xlo->xlo_flags;
+	memcpy(info->xlo_file_name, xlo->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info->xlo_crypt_name, xlo->xlo_crypt_name, XLO_NAME_SIZE);
+	info->xlo_encrypt_type = xlo->xlo_encryption ? xlo->xlo_encryption->number : 0;
+	if (xlo->xlo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
+		info->xlo_encrypt_key_size = xlo->xlo_encrypt_key_size;
+		memcpy(info->xlo_encrypt_key, xlo->xlo_encrypt_key, xlo->xlo_encrypt_key_size);
+	}
+
+	/* Drop xloop_ctl_mutex while we call into the filesystem. */
+	path = xlo->xlo_backing_file->f_path;
+	path_get(&path);
+	mutex_unlock(&xloop_ctl_mutex);
+	ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
+	if (!ret) {
+		info->xlo_device = huge_encode_dev(stat.dev);
+		info->xlo_inode = stat.ino;
+		info->xlo_rdevice = huge_encode_dev(stat.rdev);
+	}
+	path_put(&path);
+	return ret;
+}
+
+static void xloop_info64_from_old(const struct xloop_info *info, struct xloop_info64 *info64)
+{
+	memset(info64, 0, sizeof(*info64));
+	info64->xlo_number = info->xlo_number;
+	info64->xlo_device = info->xlo_device;
+	info64->xlo_inode = info->xlo_inode;
+	info64->xlo_rdevice = info->xlo_rdevice;
+	info64->xlo_offset = info->xlo_offset;
+	info64->xlo_sizelimit = 0;
+	info64->xlo_encrypt_type = info->xlo_encrypt_type;
+	info64->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
+	info64->xlo_flags = info->xlo_flags;
+	info64->xlo_init[0] = info->xlo_init[0];
+	info64->xlo_init[1] = info->xlo_init[1];
+	info64->xlo_file_fmt_type = info->xlo_file_fmt_type;
+	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info64->xlo_crypt_name, info->xlo_name, XLO_NAME_SIZE);
+	else
+		memcpy(info64->xlo_file_name, info->xlo_name, XLO_NAME_SIZE);
+	memcpy(info64->xlo_encrypt_key, info->xlo_encrypt_key, XLO_KEY_SIZE);
+}
+
+static int xloop_info64_to_old(const struct xloop_info64 *info64, struct xloop_info *info)
+{
+	memset(info, 0, sizeof(*info));
+	info->xlo_number = info64->xlo_number;
+	info->xlo_device = info64->xlo_device;
+	info->xlo_inode = info64->xlo_inode;
+	info->xlo_rdevice = info64->xlo_rdevice;
+	info->xlo_offset = info64->xlo_offset;
+	info->xlo_encrypt_type = info64->xlo_encrypt_type;
+	info->xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
+	info->xlo_flags = info64->xlo_flags;
+	info->xlo_init[0] = info64->xlo_init[0];
+	info->xlo_init[1] = info64->xlo_init[1];
+	info->xlo_file_fmt_type = info64->xlo_file_fmt_type;
+	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info->xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
+	else
+		memcpy(info->xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info->xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
+
+	/* error in case values were truncated */
+	if (info->xlo_device != info64->xlo_device || info->xlo_rdevice != info64->xlo_rdevice ||
+	    info->xlo_inode != info64->xlo_inode || info->xlo_offset != info64->xlo_offset)
+		return -EOVERFLOW;
+
+	return 0;
+}
+
+static int xloop_set_status_old(struct xloop_device *xlo, const struct xloop_info __user *arg)
+{
+	struct xloop_info info;
+	struct xloop_info64 info64;
+
+	if (copy_from_user(&info, arg, sizeof(struct xloop_info)))
+		return -EFAULT;
+	xloop_info64_from_old(&info, &info64);
+	return xloop_set_status(xlo, &info64);
+}
+
+static int xloop_set_status64(struct xloop_device *xlo, const struct xloop_info64 __user *arg)
+{
+	struct xloop_info64 info64;
+
+	if (copy_from_user(&info64, arg, sizeof(struct xloop_info64)))
+		return -EFAULT;
+	return xloop_set_status(xlo, &info64);
+}
+
+static int xloop_get_status_old(struct xloop_device *xlo, struct xloop_info __user *arg)
+{
+	struct xloop_info info;
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err)
+		err = xloop_info64_to_old(&info64, &info);
+	if (!err && copy_to_user(arg, &info, sizeof(info)))
+		err = -EFAULT;
+
+	return err;
+}
+
+static int xloop_get_status64(struct xloop_device *xlo, struct xloop_info64 __user *arg)
+{
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err && copy_to_user(arg, &info64, sizeof(info64)))
+		err = -EFAULT;
+
+	return err;
+}
+
+static int xloop_set_capacity(struct xloop_device *xlo)
+{
+	loff_t size;
+
+	if (unlikely(xlo->xlo_state != Xlo_bound))
+		return -ENXIO;
+
+	size = get_xloop_size(xlo, xlo->xlo_backing_file);
+	xloop_set_size(xlo, size);
+
+	return 0;
+}
+
+static int xloop_set_dio(struct xloop_device *xlo, unsigned long arg)
+{
+	int error = -ENXIO;
+
+	if (xlo->xlo_state != Xlo_bound)
+		goto out;
+
+	__xloop_update_dio(xlo, !!arg);
+	if (xlo->use_dio == !!arg)
+		return 0;
+	error = -EINVAL;
+out:
+	return error;
+}
+
+static int xloop_set_block_size(struct xloop_device *xlo, unsigned long arg)
+{
+	int err = 0;
+
+	if (xlo->xlo_state != Xlo_bound)
+		return -ENXIO;
+
+	err = xloop_validate_block_size(arg);
+	if (err)
+		return err;
+
+	if (xlo->xlo_queue->limits.logical_block_size == arg)
+		return 0;
+
+	sync_blockdev(xlo->xlo_device);
+	invalidate_bdev(xlo->xlo_device);
+
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	/* invalidate_bdev should have truncated all the pages */
+	if (xlo->xlo_device->bd_inode->i_mapping->nrpages) {
+		err = -EAGAIN;
+		dev_warn(xloop_device_to_dev(xlo),
+			 "xloop device has still dirty pages (nrpages=%lu)\n",
+			 xlo->xlo_device->bd_inode->i_mapping->nrpages);
+		goto out_unfreeze;
+	}
+
+	blk_queue_logical_block_size(xlo->xlo_queue, arg);
+	blk_queue_physical_block_size(xlo->xlo_queue, arg);
+	blk_queue_io_min(xlo->xlo_queue, arg);
+	xloop_update_dio(xlo);
+out_unfreeze:
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+
+	return err;
+}
+
+static int xlo_simple_ioctl(struct xloop_device *xlo, unsigned int cmd, unsigned long arg)
+{
+	int err;
+
+	err = mutex_lock_killable(&xloop_ctl_mutex);
+	if (err)
+		return err;
+	switch (cmd) {
+	case XLOOP_SET_CAPACITY:
+		err = xloop_set_capacity(xlo);
+		break;
+	case XLOOP_SET_DIRECT_IO:
+		err = xloop_set_dio(xlo, arg);
+		break;
+	case XLOOP_SET_BLOCK_SIZE:
+		err = xloop_set_block_size(xlo, arg);
+		break;
+	default:
+		err = xlo->ioctl ? xlo->ioctl(xlo, cmd, arg) : -EINVAL;
+	}
+	mutex_unlock(&xloop_ctl_mutex);
+	return err;
+}
+
+static int xlo_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
+{
+	struct xloop_device *xlo = bdev->bd_disk->private_data;
+	void __user *argp = (void __user *)arg;
+	int err;
+
+	switch (cmd) {
+	case XLOOP_SET_FD: {
+		/*
+		 * Legacy case - pass in a zeroed out struct xloop_config with
+		 * only the file descriptor set , which corresponds with the
+		 * default parameters we'd have used otherwise.
+		 */
+		struct xloop_config config;
+
+		memset(&config, 0, sizeof(config));
+		config.fd = arg;
+
+		return xloop_configure(xlo, mode, bdev, &config);
+	}
+	case XLOOP_CONFIGURE: {
+		struct xloop_config config;
+
+		if (copy_from_user(&config, argp, sizeof(config)))
+			return -EFAULT;
+
+		return xloop_configure(xlo, mode, bdev, &config);
+	}
+	case XLOOP_CHANGE_FD:
+		return xloop_change_fd(xlo, bdev, arg);
+	case XLOOP_CLR_FD:
+		return xloop_clr_fd(xlo);
+	case XLOOP_SET_STATUS:
+		err = -EPERM;
+		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+			err = xloop_set_status_old(xlo, argp);
+		break;
+	case XLOOP_GET_STATUS:
+		return xloop_get_status_old(xlo, argp);
+	case XLOOP_SET_STATUS64:
+		err = -EPERM;
+		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+			err = xloop_set_status64(xlo, argp);
+		break;
+	case XLOOP_GET_STATUS64:
+		return xloop_get_status64(xlo, argp);
+	case XLOOP_SET_CAPACITY:
+	case XLOOP_SET_DIRECT_IO:
+	case XLOOP_SET_BLOCK_SIZE:
+		if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 4, 0)
+		fallthrough;
+#else
+			/* fall through */
+#endif
+	default:
+		err = xlo_simple_ioctl(xlo, cmd, arg);
+		break;
+	}
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_xloop_info {
+	compat_int_t   xlo_number;                    /* ioctl r/o */
+	compat_dev_t   xlo_device;                    /* ioctl r/o */
+	compat_ulong_t xlo_inode;                     /* ioctl r/o */
+	compat_dev_t   xlo_rdevice;                   /* ioctl r/o */
+	compat_int_t   xlo_offset;
+	compat_int_t   xlo_encrypt_type;
+	compat_int_t   xlo_encrypt_key_size;          /* ioctl w/o */
+	compat_int_t   xlo_flags;                     /* ioctl r/o */
+	char           xlo_name[XLO_NAME_SIZE];
+	unsigned char  xlo_encrypt_key[XLO_KEY_SIZE]; /* ioctl w/o */
+	compat_ulong_t xlo_init[2];
+	char           reserved[4];
+	compat_int_t   xlo_file_fmt_type;
+};
+
+/*
+ * Transfer 32-bit compatibility structure in userspace to 64-bit xloop info
+ * - noinlined to reduce stack space usage in main part of driver
+ */
+static noinline int xloop_info64_from_compat(const struct compat_xloop_info __user *arg, struct xloop_info64 *info64)
+{
+	struct compat_xloop_info info;
+
+	if (copy_from_user(&info, arg, sizeof(info)))
+		return -EFAULT;
+
+	memset(info64, 0, sizeof(*info64));
+	info64->xlo_number = info.xlo_number;
+	info64->xlo_device = info.xlo_device;
+	info64->xlo_inode = info.xlo_inode;
+	info64->xlo_rdevice = info.xlo_rdevice;
+	info64->xlo_offset = info.xlo_offset;
+	info64->xlo_sizelimit = 0;
+	info64->xlo_encrypt_type = info.xlo_encrypt_type;
+	info64->xlo_encrypt_key_size = info.xlo_encrypt_key_size;
+	info64->xlo_flags = info.xlo_flags;
+	info64->xlo_init[0] = info.xlo_init[0];
+	info64->xlo_init[1] = info.xlo_init[1];
+	info64->xlo_file_fmt_type = info.xlo_file_fmt_type;
+	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info64->xlo_crypt_name, info.xlo_name, XLO_NAME_SIZE);
+	else
+		memcpy(info64->xlo_file_name, info.xlo_name, XLO_NAME_SIZE);
+	memcpy(info64->xlo_encrypt_key, info.xlo_encrypt_key, XLO_KEY_SIZE);
+	return 0;
+}
+
+/*
+ * Transfer 64-bit xloop info to 32-bit compatibility structure in userspace
+ * - noinlined to reduce stack space usage in main part of driver
+ */
+static noinline int xloop_info64_to_compat(const struct xloop_info64 *info64, struct compat_xloop_info __user *arg)
+{
+	struct compat_xloop_info info;
+
+	memset(&info, 0, sizeof(info));
+	info.xlo_number = info64->xlo_number;
+	info.xlo_device = info64->xlo_device;
+	info.xlo_inode = info64->xlo_inode;
+	info.xlo_rdevice = info64->xlo_rdevice;
+	info.xlo_offset = info64->xlo_offset;
+	info.xlo_encrypt_type = info64->xlo_encrypt_type;
+	info.xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
+	info.xlo_flags = info64->xlo_flags;
+	info.xlo_init[0] = info64->xlo_init[0];
+	info.xlo_init[1] = info64->xlo_init[1];
+	info.xlo_file_fmt_type = info64->xlo_file_fmt_type;
+	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info.xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
+	else
+		memcpy(info.xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info.xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
+
+	/* error in case values were truncated */
+	if (info.xlo_device != info64->xlo_device || info.xlo_rdevice != info64->xlo_rdevice ||
+	    info.xlo_inode != info64->xlo_inode || info.xlo_offset != info64->xlo_offset ||
+	    info.xlo_init[0] != info64->xlo_init[0] || info.xlo_init[1] != info64->xlo_init[1] ||
+	    info.xlo_file_fmt_type != info64->xlo_file_fmt_type)
+		return -EOVERFLOW;
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+	return 0;
+}
+
+static int xloop_set_status_compat(struct xloop_device *xlo, const struct compat_xloop_info __user *arg)
+{
+	struct xloop_info64 info64;
+	int ret;
+
+	ret = xloop_info64_from_compat(arg, &info64);
+	if (ret < 0)
+		return ret;
+	return xloop_set_status(xlo, &info64);
+}
+
+static int xloop_get_status_compat(struct xloop_device *xlo, struct compat_xloop_info __user *arg)
+{
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err)
+		err = xloop_info64_to_compat(&info64, arg);
+	return err;
+}
+
+static int xlo_compat_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
+{
+	struct xloop_device *xlo = bdev->bd_disk->private_data;
+	int err;
+
+	switch (cmd) {
+	case XLOOP_SET_STATUS:
+		err = xloop_set_status_compat(xlo, (const struct compat_xloop_info __user *)arg);
+		break;
+	case XLOOP_GET_STATUS:
+		err = xloop_get_status_compat(xlo, (struct compat_xloop_info __user *)arg);
+		break;
+	case XLOOP_SET_CAPACITY:
+	case XLOOP_CLR_FD:
+	case XLOOP_GET_STATUS64:
+	case XLOOP_SET_STATUS64:
+	case XLOOP_CONFIGURE:
+		arg = (unsigned long)compat_ptr(arg);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 4, 0)
+		fallthrough;
+#else
+		/* fall through */
+#endif
+	case XLOOP_SET_FD:
+	case XLOOP_CHANGE_FD:
+	case XLOOP_SET_BLOCK_SIZE:
+	case XLOOP_SET_DIRECT_IO:
+		err = xlo_ioctl(bdev, mode, cmd, arg);
+		break;
+	default:
+		err = -ENOIOCTLCMD;
+		break;
+	}
+	return err;
+}
+#endif
+
+static int xlo_open(struct block_device *bdev, fmode_t mode)
+{
+	struct xloop_device *xlo;
+	int err;
+
+	err = mutex_lock_killable(&xloop_ctl_mutex);
+	if (err)
+		return err;
+	xlo = bdev->bd_disk->private_data;
+	if (!xlo) {
+		err = -ENXIO;
+		goto out;
+	}
+
+	atomic_inc(&xlo->xlo_refcnt);
+out:
+	mutex_unlock(&xloop_ctl_mutex);
+	return err;
+}
+
+static void xlo_release(struct gendisk *disk, fmode_t mode)
+{
+	struct xloop_device *xlo;
+
+	mutex_lock(&xloop_ctl_mutex);
+	xlo = disk->private_data;
+	if (atomic_dec_return(&xlo->xlo_refcnt))
+		goto out_unlock;
+
+	if (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR) {
+		if (xlo->xlo_state != Xlo_bound)
+			goto out_unlock;
+		xlo->xlo_state = Xlo_rundown;
+		mutex_unlock(&xloop_ctl_mutex);
+		/*
+		 * In autoclear mode, stop the xloop thread
+		 * and remove configuration after last close.
+		 */
+		__xloop_clr_fd(xlo, true);
+		return;
+	} else if (xlo->xlo_state == Xlo_bound) {
+		/*
+		 * Otherwise keep thread (if running) and config,
+		 * but flush possible ongoing bios in thread.
+		 */
+		blk_mq_freeze_queue(xlo->xlo_queue);
+		blk_mq_unfreeze_queue(xlo->xlo_queue);
+	}
+
+out_unlock:
+	mutex_unlock(&xloop_ctl_mutex);
+}
+
+static const struct block_device_operations xlo_fops = {
+	.owner        = THIS_MODULE,
+	.open         = xlo_open,
+	.release      = xlo_release,
+	.ioctl        = xlo_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl = xlo_compat_ioctl,
+#endif
+};
+
+/*
+ * And now the modules code and kernel interface.
+ */
+static int max_xloop;
+module_param(max_xloop, int, 0444);
+MODULE_PARM_DESC(max_xloop, "Maximum number of xloop devices");
+module_param(max_part, int, 0444);
+MODULE_PARM_DESC(max_part, "Maximum number of partitions per xloop device");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Manuel Bentele <development@manuel-bentele.de>");
+MODULE_VERSION(XLOOP_VERSION);
+MODULE_ALIAS_BLOCKDEV_MAJOR(XLOOP_MAJOR);
+
+int xloop_register_transfer(struct xloop_func_table *funcs)
+{
+	unsigned int n = funcs->number;
+
+	if (n >= MAX_XLO_CRYPT || xfer_funcs[n])
+		return -EINVAL;
+	xfer_funcs[n] = funcs;
+	return 0;
+}
+EXPORT_SYMBOL(xloop_register_transfer);
+
+static int unregister_transfer_cb(int id, void *ptr, void *data)
+{
+	struct xloop_device *xlo = ptr;
+	struct xloop_func_table *xfer = data;
+
+	mutex_lock(&xloop_ctl_mutex);
+	if (xlo->xlo_encryption == xfer)
+		xloop_release_xfer(xlo);
+	mutex_unlock(&xloop_ctl_mutex);
+	return 0;
+}
+
+int xloop_unregister_transfer(int number)
+{
+	unsigned int n = number;
+	struct xloop_func_table *xfer;
+
+	xfer = xfer_funcs[n];
+
+	if (n == 0 || n >= MAX_XLO_CRYPT || xfer == NULL)
+		return -EINVAL;
+
+	xfer_funcs[n] = NULL;
+	idr_for_each(&xloop_index_idr, &unregister_transfer_cb, xfer);
+	return 0;
+}
+EXPORT_SYMBOL(xloop_unregister_transfer);
+
+static blk_status_t xloop_queue_rq(struct blk_mq_hw_ctx *hctx, const struct blk_mq_queue_data *bd)
+{
+	struct request *rq = bd->rq;
+	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+	struct xloop_device *xlo = rq->q->queuedata;
+
+	blk_mq_start_request(rq);
+
+	if (xlo->xlo_state != Xlo_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 = xlo->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(&xlo->worker, &cmd->work);
+
+	return BLK_STS_OK;
+}
+
+static void xloop_handle_cmd(struct xloop_cmd *cmd)
+{
+	struct request *rq = blk_mq_rq_from_pdu(cmd);
+	const bool write = op_is_write(req_op(rq));
+	struct xloop_device *xlo = rq->q->queuedata;
+	int ret = 0;
+
+	if (write && (xlo->xlo_flags & XLO_FLAGS_READ_ONLY)) {
+		ret = -EIO;
+		goto failed;
+	}
+
+	ret = do_req_filebacked(xlo, rq);
+failed:
+	/* complete non-aio request */
+	if (!cmd->use_aio || ret) {
+		if (ret == -EOPNOTSUPP)
+			cmd->ret = ret;
+		else
+			cmd->ret = ret ? -EIO : 0;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 9, 0)
+		if (likely(!blk_should_fake_timeout(rq->q)))
+			blk_mq_complete_request(rq);
+#else
+		blk_mq_complete_request(rq);
+#endif
+	}
+}
+
+static void xloop_queue_work(struct kthread_work *work)
+{
+	struct xloop_cmd *cmd = container_of(work, struct xloop_cmd, work);
+
+	xloop_handle_cmd(cmd);
+}
+
+static int xloop_init_request(struct blk_mq_tag_set *set, struct request *rq, unsigned int hctx_idx,
+			      unsigned int numa_node)
+{
+	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+
+	kthread_init_work(&cmd->work, xloop_queue_work);
+	return 0;
+}
+
+static const struct blk_mq_ops xloop_mq_ops = {
+	.queue_rq = xloop_queue_rq,
+	.init_request = xloop_init_request,
+	.complete = xlo_complete_rq,
+};
+
+static struct dentry *xloop_dbgfs_dir;
+
+static int xloop_add(struct xloop_device **l, int i)
+{
+	struct xloop_device *xlo;
+	struct gendisk *disk;
+	int err;
+
+	err = -ENOMEM;
+	xlo = kzalloc(sizeof(*xlo), GFP_KERNEL);
+	if (!xlo)
+		goto out;
+
+	xlo->xlo_state = Xlo_unbound;
+
+	/* allocate id, if @id >= 0, we're requesting that specific id */
+	if (i >= 0) {
+		err = idr_alloc(&xloop_index_idr, xlo, i, i + 1, GFP_KERNEL);
+		if (err == -ENOSPC)
+			err = -EEXIST;
+	} else {
+		err = idr_alloc(&xloop_index_idr, xlo, 0, 0, GFP_KERNEL);
+	}
+	if (err < 0)
+		goto out_free_dev;
+	i = err;
+
+	err = -ENOMEM;
+	xlo->tag_set.ops = &xloop_mq_ops;
+	xlo->tag_set.nr_hw_queues = 1;
+	xlo->tag_set.queue_depth = 128;
+	xlo->tag_set.numa_node = NUMA_NO_NODE;
+	xlo->tag_set.cmd_size = sizeof(struct xloop_cmd);
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 8, 0)
+	xlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
+#else
+	xlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+#endif
+	xlo->tag_set.driver_data = xlo;
+
+	err = blk_mq_alloc_tag_set(&xlo->tag_set);
+	if (err)
+		goto out_free_idr;
+
+	xlo->xlo_queue = blk_mq_init_queue(&xlo->tag_set);
+	if (IS_ERR(xlo->xlo_queue)) {
+		err = PTR_ERR(xlo->xlo_queue);
+		goto out_cleanup_tags;
+	}
+	xlo->xlo_queue->queuedata = xlo;
+
+	blk_queue_max_hw_sectors(xlo->xlo_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, xlo->xlo_queue);
+
+	err = -ENOMEM;
+	xlo->xlo_fmt = xloop_file_fmt_alloc();
+	if (!xlo->xlo_fmt)
+		goto out_free_queue;
+
+	xloop_file_fmt_set_xlo(xlo->xlo_fmt, xlo);
+
+	err = -ENOMEM;
+	disk = xlo->xlo_disk = alloc_disk(1 << part_shift);
+	if (!disk)
+		goto out_free_file_fmt;
+
+	/*
+	 * 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 xloop device numbers will continue
+	 * to match the xloop minors, regardless of the number of partitions
+	 * used.
+	 *
+	 * If max_part is given, partition scanning is globally enabled for
+	 * all xloop devices. The minors for the main xloop devices will be
+	 * multiples of max_part.
+	 *
+	 * Note: Global-for-all-devices, set-only-at-init, read-only module
+	 * parameteters like 'max_xloop' 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(&xlo->xlo_refcnt, 0);
+	xlo->xlo_number = i;
+	spin_lock_init(&xlo->xlo_lock);
+	disk->major = XLOOP_MAJOR;
+	disk->first_minor = i << part_shift;
+	disk->fops = &xlo_fops;
+	disk->private_data = xlo;
+	disk->queue = xlo->xlo_queue;
+	sprintf(disk->disk_name, "xloop%d", i);
+	add_disk(disk);
+	*l = xlo;
+
+	/*
+	 * initialize debugfs entries
+	 *
+	 * create for each loop device a debugfs directory under 'loop' if
+	 * the 'block' directory exists, otherwise create the loop directory in
+	 * the root directory
+	 */
+#ifdef CONFIG_DEBUG_FS
+	xlo->xlo_dbgfs_dir = debugfs_create_dir(disk->disk_name, xloop_dbgfs_dir);
+
+	if (IS_ERR_OR_NULL(xlo->xlo_dbgfs_dir)) {
+		err = -ENODEV;
+		xlo->xlo_dbgfs_dir = NULL;
+		goto out_free_file_fmt;
+	}
+#endif
+
+	return xlo->xlo_number;
+
+out_free_file_fmt:
+	xloop_file_fmt_free(xlo->xlo_fmt);
+out_free_queue:
+	blk_cleanup_queue(xlo->xlo_queue);
+out_cleanup_tags:
+	blk_mq_free_tag_set(&xlo->tag_set);
+out_free_idr:
+	idr_remove(&xloop_index_idr, i);
+out_free_dev:
+	kfree(xlo);
+out:
+	return err;
+}
+
+static void xloop_remove(struct xloop_device *xlo)
+{
+	xloop_file_fmt_free(xlo->xlo_fmt);
+	debugfs_remove(xlo->xlo_dbgfs_dir);
+	del_gendisk(xlo->xlo_disk);
+	blk_cleanup_queue(xlo->xlo_queue);
+	blk_mq_free_tag_set(&xlo->tag_set);
+	put_disk(xlo->xlo_disk);
+	kfree(xlo);
+}
+
+static int find_free_cb(int id, void *ptr, void *data)
+{
+	struct xloop_device *xlo = ptr;
+	struct xloop_device **l = data;
+
+	if (xlo->xlo_state == Xlo_unbound) {
+		*l = xlo;
+		return 1;
+	}
+	return 0;
+}
+
+static int xloop_lookup(struct xloop_device **l, int i)
+{
+	struct xloop_device *xlo;
+	int ret = -ENODEV;
+
+	if (i < 0) {
+		int err;
+
+		err = idr_for_each(&xloop_index_idr, &find_free_cb, &xlo);
+		if (err == 1) {
+			*l = xlo;
+			ret = xlo->xlo_number;
+		}
+		goto out;
+	}
+
+	/* lookup and return a specific i */
+	xlo = idr_find(&xloop_index_idr, i);
+	if (xlo) {
+		*l = xlo;
+		ret = xlo->xlo_number;
+	}
+out:
+	return ret;
+}
+
+static struct kobject *xloop_probe(dev_t dev, int *part, void *data)
+{
+	struct xloop_device *xlo;
+	struct kobject *kobj;
+	int err;
+
+	mutex_lock(&xloop_ctl_mutex);
+	err = xloop_lookup(&xlo, MINOR(dev) >> part_shift);
+	if (err < 0)
+		err = xloop_add(&xlo, MINOR(dev) >> part_shift);
+	if (err < 0)
+		kobj = NULL;
+	else
+		kobj = get_disk_and_module(xlo->xlo_disk);
+	mutex_unlock(&xloop_ctl_mutex);
+
+	*part = 0;
+	return kobj;
+}
+
+static long xloop_control_ioctl(struct file *file, unsigned int cmd, unsigned long parm)
+{
+	struct xloop_device *xlo;
+	int ret;
+
+	ret = mutex_lock_killable(&xloop_ctl_mutex);
+	if (ret)
+		return ret;
+
+	ret = -EINVAL;
+	switch (cmd) {
+	case XLOOP_CTL_ADD:
+		ret = xloop_lookup(&xlo, parm);
+		if (ret >= 0) {
+			ret = -EEXIST;
+			break;
+		}
+		ret = xloop_add(&xlo, parm);
+		break;
+	case XLOOP_CTL_REMOVE:
+		ret = xloop_lookup(&xlo, parm);
+		if (ret < 0)
+			break;
+		if (xlo->xlo_state != Xlo_unbound) {
+			ret = -EBUSY;
+			break;
+		}
+		if (atomic_read(&xlo->xlo_refcnt) > 0) {
+			ret = -EBUSY;
+			break;
+		}
+		xlo->xlo_disk->private_data = NULL;
+		idr_remove(&xloop_index_idr, xlo->xlo_number);
+		xloop_remove(xlo);
+		break;
+	case XLOOP_CTL_GET_FREE:
+		ret = xloop_lookup(&xlo, -1);
+		if (ret >= 0)
+			break;
+		ret = xloop_add(&xlo, -1);
+	}
+	mutex_unlock(&xloop_ctl_mutex);
+
+	return ret;
+}
+
+static const struct file_operations xloop_ctl_fops = {
+	.open           = nonseekable_open,
+	.unlocked_ioctl = xloop_control_ioctl,
+	.compat_ioctl   = xloop_control_ioctl,
+	.owner          = THIS_MODULE,
+	.llseek         = noop_llseek,
+};
+
+static struct miscdevice xloop_misc = {
+	.minor = XLOOP_CTRL_MINOR,
+	.name  = "xloop-control",
+	.fops  = &xloop_ctl_fops,
+};
+
+MODULE_ALIAS_MISCDEV(XLOOP_CTRL_MINOR);
+MODULE_ALIAS("devname:xloop-control");
+
+static int __init xloop_init(void)
+{
+	int i, nr;
+	unsigned long range;
+	struct xloop_device *xlo;
+	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_xloop > 1UL << (MINORBITS - part_shift)) {
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	/*
+	 * If max_xloop is specified, create that many devices upfront.
+	 * This also becomes a hard limit. If max_xloop is not specified,
+	 * create CONFIG_BLK_DEV_XLOOP_MIN_COUNT xloop devices at module
+	 * init time. xloop devices can be requested on-demand with the
+	 * /dev/xloop-control interface, or be instantiated by accessing
+	 * a 'dead' device node.
+	 */
+	if (max_xloop) {
+		nr = CONFIG_BLK_DEV_XLOOP_MIN_COUNT;
+		range = 1UL << MINORBITS;
+	}
+
+	err = misc_register(&xloop_misc);
+	if (err < 0)
+		goto err_out;
+
+	if (register_blkdev(XLOOP_MAJOR, "xloop")) {
+		err = -EIO;
+		goto misc_out;
+	}
+
+#ifdef CONFIG_DEBUG_FS
+	xloop_dbgfs_dir = debugfs_create_dir("xloop", NULL);
+	if (IS_ERR_OR_NULL(xloop_dbgfs_dir)) {
+		err = -ENODEV;
+		goto misc_out;
+	}
+#endif
+
+	blk_register_region(MKDEV(XLOOP_MAJOR, 0), range, THIS_MODULE, xloop_probe, NULL, NULL);
+
+	/* pre-create number of devices given by config or max_xloop */
+	mutex_lock(&xloop_ctl_mutex);
+	for (i = 0; i < nr; i++)
+		xloop_add(&xlo, i);
+	mutex_unlock(&xloop_ctl_mutex);
+
+	pr_info("module in version %s loaded\n", XLOOP_VERSION);
+	return 0;
+
+misc_out:
+	misc_deregister(&xloop_misc);
+err_out:
+	return err;
+}
+
+static int xloop_exit_cb(int id, void *ptr, void *data)
+{
+	struct xloop_device *xlo = ptr;
+
+	xloop_remove(xlo);
+	return 0;
+}
+
+static void __exit xloop_exit(void)
+{
+	unsigned long range;
+
+	range = max_xloop ? max_xloop << part_shift : 1UL << MINORBITS;
+
+	mutex_lock(&xloop_ctl_mutex);
+
+	idr_for_each(&xloop_index_idr, &xloop_exit_cb, NULL);
+	idr_destroy(&xloop_index_idr);
+
+	blk_unregister_region(MKDEV(XLOOP_MAJOR, 0), range);
+	unregister_blkdev(XLOOP_MAJOR, "xloop");
+
+#ifdef CONFIG_DEBUG_FS
+	debugfs_remove(xloop_dbgfs_dir);
+#endif
+
+	misc_deregister(&xloop_misc);
+
+	mutex_unlock(&xloop_ctl_mutex);
+
+	pr_info("exit module\n");
+}
+
+module_init(xloop_init);
+module_exit(xloop_exit);
+
+#ifndef MODULE
+static int __init max_xloop_setup(char *str)
+{
+	max_xloop = simple_strtol(str, NULL, 0);
+	return 1;
+}
+
+__setup("max_xloop=", max_xloop_setup);
+#endif
diff --git a/src/kernel/xloop_main_4.18.h b/src/kernel/xloop_main_4.18.h
new file mode 100644
index 0000000..97c2654
--- /dev/null
+++ b/src/kernel/xloop_main_4.18.h
@@ -0,0 +1,104 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_main.h
+ *
+ * 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.
+ */
+#ifndef _LINUX_XLOOP_H
+#define _LINUX_XLOOP_H
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include <linux/kthread.h>
+#include "uapi_xloop.h"
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
+
+#include "xloop_file_fmt.h"
+
+/* Possible states of device */
+enum {
+	Xlo_unbound,
+	Xlo_bound,
+	Xlo_rundown,
+};
+
+struct xloop_func_table;
+
+struct xloop_device {
+	int                     xlo_number;
+	atomic_t                xlo_refcnt;
+	loff_t                  xlo_offset;
+	loff_t                  xlo_sizelimit;
+	int                     xlo_flags;
+	int                    (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page,
+					unsigned int raw_off, struct page *xloop_page, unsigned int xloop_off,
+					int size, sector_t real_block);
+	char                    xlo_file_name[XLO_NAME_SIZE];
+	char                    xlo_crypt_name[XLO_NAME_SIZE];
+	char                    xlo_encrypt_key[XLO_KEY_SIZE];
+	int                     xlo_encrypt_key_size;
+	struct xloop_func_table *xlo_encryption;
+	__u32                   xlo_init[2];
+	kuid_t                  xlo_key_owner; /* Who set the key */
+	int                     (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
+
+	struct xloop_file_fmt   *xlo_fmt;
+
+	struct file             *xlo_backing_file;
+	struct block_device     *xlo_device;
+	void                    *key_data;
+
+	gfp_t                   old_gfp_mask;
+
+	spinlock_t              xlo_lock;
+	int                     xlo_state;
+	struct kthread_worker   worker;
+	struct task_struct      *worker_task;
+	bool                    use_dio;
+	bool                    sysfs_inited;
+
+	struct request_queue    *xlo_queue;
+	struct blk_mq_tag_set   tag_set;
+	struct gendisk          *xlo_disk;
+
+#ifdef CONFIG_DEBUG_FS
+	struct dentry           *xlo_dbgfs_dir;
+#endif
+};
+
+struct xloop_cmd {
+	struct kthread_work        work;
+	bool                       use_aio; /* use AIO interface to handle I/O */
+	atomic_t                   ref;     /* only for aio */
+	long                       ret;
+	struct kiocb               iocb;
+	struct bio_vec             *bvec;
+	struct cgroup_subsys_state *css;
+};
+
+/* Support for loadable transfer modules */
+struct xloop_func_table {
+	int           number; /* filter type */
+	int           (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned int raw_off,
+				struct page *xloop_page, unsigned int xloop_off, int size, sector_t real_block);
+	int           (*init)(struct xloop_device *xlo, const struct xloop_info64 *info);
+	/* release is called from xloop_unregister_transfer or clr_fd */
+	int           (*release)(struct xloop_device *xlo);
+	int           (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
+	struct module *owner;
+};
+
+extern inline struct device *xloop_device_to_dev(struct xloop_device *xlo);
+
+int xloop_register_transfer(struct xloop_func_table *funcs);
+int xloop_unregister_transfer(int number);
+
+#endif
diff --git a/src/kernel/xloop_main_5.15.c b/src/kernel/xloop_main_5.15.c
new file mode 100644
index 0000000..d133709
--- /dev/null
+++ b/src/kernel/xloop_main_5.15.c
@@ -0,0 +1,2413 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * xloop_main.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_xloop_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 xloop devices now dynamic via max_xloop module parameter.
+ * Russell Kroll <rkroll@exploits.org> 19990701
+ *
+ * Maximum number of xloop devices when compiled-in now selectable by passing
+ * max_xloop=<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 xloop 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
+ *
+ * Support for using file formats.
+ * Manuel Bentele <development@manuel-bentele.de>, 2019
+ *
+ * Still To Fix:
+ * - Advisory locking is ignored here.
+ * - Should use an own CAP_* category instead of CAP_SYS_ADMIN
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#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 <linux/version.h>
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
+
+#include <xloop/version.h>
+
+#include "xloop_file_fmt.h"
+#include "xloop_main.h"
+
+#include <linux/uaccess.h>
+
+#define XLOOP_IDLE_WORKER_TIMEOUT (60 * HZ)
+
+static DEFINE_IDR(xloop_index_idr);
+static DEFINE_MUTEX(xloop_ctl_mutex);
+static DEFINE_MUTEX(xloop_validate_mutex);
+
+/**
+ * xloop_global_lock_killable() - take locks for safe xloop_validate_file() test
+ *
+ * @xlo: struct xloop_device
+ * @global: true if @xlo is about to bind another "struct xloop_device", false otherwise
+ *
+ * Returns 0 on success, -EINTR otherwise.
+ *
+ * Since xloop_validate_file() traverses on other "struct xloop_device" if
+ * is_xloop_device() is true, we need a global lock for serializing concurrent
+ * xloop_configure()/xloop_change_fd()/__xloop_clr_fd() calls.
+ */
+static int xloop_global_lock_killable(struct xloop_device *xlo, bool global)
+{
+	int err;
+
+	if (global) {
+		err = mutex_lock_killable(&xloop_validate_mutex);
+		if (err)
+			return err;
+	}
+	err = mutex_lock_killable(&xlo->xlo_mutex);
+	if (err && global)
+		mutex_unlock(&xloop_validate_mutex);
+	return err;
+}
+
+/**
+ * xloop_global_unlock() - release locks taken by xloop_global_lock_killable()
+ *
+ * @xlo: struct xloop_device
+ * @global: true if @xlo was about to bind another "struct xloop_device", false otherwise
+ */
+static void xloop_global_unlock(struct xloop_device *xlo, bool global)
+{
+	mutex_unlock(&xlo->xlo_mutex);
+	if (global)
+		mutex_unlock(&xloop_validate_mutex);
+}
+
+static int max_part;
+static int part_shift;
+
+struct device *xloop_device_to_dev(struct xloop_device *xlo)
+{
+	return disk_to_dev(xlo->xlo_disk);
+}
+EXPORT_SYMBOL(xloop_device_to_dev);
+
+static int transfer_xor(struct xloop_device *xlo, int cmd,
+			struct page *raw_page, unsigned raw_off,
+			struct page *xloop_page, unsigned xloop_off,
+			int size, sector_t real_block)
+{
+	char *raw_buf = kmap_atomic(raw_page) + raw_off;
+	char *xloop_buf = kmap_atomic(xloop_page) + xloop_off;
+	char *in, *out, *key;
+	int i, keysize;
+
+	if (cmd == READ) {
+		in = raw_buf;
+		out = xloop_buf;
+	} else {
+		in = xloop_buf;
+		out = raw_buf;
+	}
+
+	key = xlo->xlo_encrypt_key;
+	keysize = xlo->xlo_encrypt_key_size;
+	for (i = 0; i < size; i++)
+		*out++ = *in++ ^ key[(i & 511) % keysize];
+
+	kunmap_atomic(xloop_buf);
+	kunmap_atomic(raw_buf);
+	cond_resched();
+	return 0;
+}
+
+static int xor_init(struct xloop_device *xlo, const struct xloop_info64 *info)
+{
+	if (unlikely(info->xlo_encrypt_key_size <= 0))
+		return -EINVAL;
+	return 0;
+}
+
+static struct xloop_func_table none_funcs = {
+	.number = XLO_CRYPT_NONE,
+};
+
+static struct xloop_func_table xor_funcs = {
+	.number = XLO_CRYPT_XOR,
+	.transfer = transfer_xor,
+	.init = xor_init
+};
+
+/* xfer_funcs[0] is special - its release function is never called */
+static struct xloop_func_table *xfer_funcs[MAX_XLO_CRYPT] = {
+	&none_funcs,
+	&xor_funcs
+};
+
+static loff_t get_xloop_size(struct xloop_device *xlo, struct file *file)
+{
+	return xloop_file_fmt_sector_size(xlo->xlo_fmt, file, xlo->xlo_offset, xlo->xlo_sizelimit);
+}
+
+static void __xloop_update_dio(struct xloop_device *xlo, bool dio)
+{
+	struct file *file = xlo->xlo_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 xlo_offset is aligned with the
+	 * logical I/O size of backing device, and the logical block
+	 * size of xloop is bigger than the backing device's and the xloop
+	 * 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(xlo->xlo_queue) >= sb_bsize &&
+				!(xlo->xlo_offset & dio_align) &&
+				mapping->a_ops->direct_IO &&
+				!xlo->transfer)
+			use_dio = true;
+		else
+			use_dio = false;
+	} else {
+		use_dio = false;
+	}
+
+	if (xlo->use_dio == use_dio)
+		return;
+
+	/* flush dirty pages before changing direct IO */
+	xloop_file_fmt_flush(xlo->xlo_fmt);
+
+	/*
+	 * The flag of XLO_FLAGS_DIRECT_IO is handled similarly with
+	 * XLO_FLAGS_READ_ONLY, both are set from kernel, and xlosetup
+	 * will get updated by ioctl(XLOOP_GET_STATUS)
+	 */
+	if (xlo->xlo_state == Xlo_bound)
+		blk_mq_freeze_queue(xlo->xlo_queue);
+	xlo->use_dio = use_dio;
+	if (use_dio) {
+		blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
+		xlo->xlo_flags |= XLO_FLAGS_DIRECT_IO;
+	} else {
+		blk_queue_flag_set(QUEUE_FLAG_NOMERGES, xlo->xlo_queue);
+		xlo->xlo_flags &= ~XLO_FLAGS_DIRECT_IO;
+	}
+	if (xlo->xlo_state == Xlo_bound)
+		blk_mq_unfreeze_queue(xlo->xlo_queue);
+}
+
+/**
+ * xloop_set_size() - sets device size and notifies userspace
+ * @xlo: struct xloop_device to set the size for
+ * @size: new size of the xloop device
+ *
+ * Callers must validate that the size passed into this function fits into
+ * a sector_t, eg using xloop_validate_size()
+ */
+static void xloop_set_size(struct xloop_device *xlo, loff_t size)
+{
+	if (!set_capacity_and_notify(xlo->xlo_disk, size))
+		kobject_uevent(&disk_to_dev(xlo->xlo_disk)->kobj, KOBJ_CHANGE);
+}
+
+static inline int
+xlo_do_transfer(struct xloop_device *xlo, int cmd,
+	       struct page *rpage, unsigned roffs,
+	       struct page *lpage, unsigned loffs,
+	       int size, sector_t rblock)
+{
+	int ret;
+
+	ret = xlo->transfer(xlo, cmd, rpage, roffs, lpage, loffs, size, rblock);
+	if (likely(!ret))
+		return 0;
+
+	pr_err_ratelimited("Transfer error at byte offset %llu, length %i.\n",
+		(unsigned long long)rblock << 9, size);
+	return ret;
+}
+
+static void xlo_complete_rq(struct request *rq)
+{
+	struct xloop_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 int do_req_filebacked(struct xloop_device *xlo, struct request *rq)
+{
+	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+
+	/*
+	 * xlo_write_simple and xlo_read_simple should have been covered
+	 * by io submit style function like xloop_file_fmt_read_aio(), one
+	 * blocker is that xloop_file_fmt_read() 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 xloop_file_fmt_flush(xlo->xlo_fmt);
+	case REQ_OP_WRITE_ZEROES:
+		return xloop_file_fmt_write_zeros(xlo->xlo_fmt, rq);
+	case REQ_OP_DISCARD:
+		return xloop_file_fmt_discard(xlo->xlo_fmt, rq);
+	case REQ_OP_WRITE:
+		if (cmd->use_aio)
+			return xloop_file_fmt_write_aio(xlo->xlo_fmt, rq);
+		else
+			return xloop_file_fmt_write(xlo->xlo_fmt, rq);
+	case REQ_OP_READ:
+		if (cmd->use_aio)
+			return xloop_file_fmt_read_aio(xlo->xlo_fmt, rq);
+		else
+			return xloop_file_fmt_read(xlo->xlo_fmt, rq);
+	default:
+		WARN_ON_ONCE(1);
+		return -EIO;
+	}
+}
+
+static inline void xloop_update_dio(struct xloop_device *xlo)
+{
+	__xloop_update_dio(xlo, (xlo->xlo_backing_file->f_flags & O_DIRECT) |
+				xlo->use_dio);
+}
+
+static void xloop_reread_partitions(struct xloop_device *xlo)
+{
+	int rc;
+
+	mutex_lock(&xlo->xlo_disk->open_mutex);
+	rc = bdev_disk_changed(xlo->xlo_disk, false);
+	mutex_unlock(&xlo->xlo_disk->open_mutex);
+	if (rc)
+		dev_warn(xloop_device_to_dev(xlo),
+			"partition scan of xloop%d (%s) failed (rc=%d)\n",
+			xlo->xlo_number, xlo->xlo_file_name, rc);
+}
+
+static inline int is_xloop_device(struct file *file)
+{
+	struct inode *i = file->f_mapping->host;
+
+	return i && S_ISBLK(i->i_mode) && imajor(i) == XLOOP_MAJOR;
+}
+
+static int xloop_validate_file(struct file *file, struct block_device *bdev)
+{
+	struct inode	*inode = file->f_mapping->host;
+	struct file	*f = file;
+
+	/* Avoid recursion */
+	while (is_xloop_device(f)) {
+		struct xloop_device *l;
+
+		lockdep_assert_held(&xloop_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->xlo_state != Xlo_bound)
+			return -EINVAL;
+		/* Order wrt setting xlo->xlo_backing_file in xloop_configure(). */
+		rmb();
+		f = l->xlo_backing_file;
+	}
+	if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ * xloop_change_fd switched the backing store of a xloopback 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 xloop device is used read-only, and if the
+ * new backing store is the same size and type as the old backing store.
+ */
+static int xloop_change_fd(struct xloop_device *xlo, struct block_device *bdev,
+			  unsigned int arg)
+{
+	struct file *file = fget(arg);
+	struct file *old_file;
+	int error;
+	bool partscan;
+	bool is_xloop;
+
+	if (!file)
+		return -EBADF;
+	is_xloop = is_xloop_device(file);
+	error = xloop_global_lock_killable(xlo, is_xloop);
+	if (error)
+		goto out_putf;
+	error = -ENXIO;
+	if (xlo->xlo_state != Xlo_bound)
+		goto out_err;
+
+	/* the xloop device has to be read-only */
+	error = -EINVAL;
+	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY))
+		goto out_err;
+
+	error = xloop_validate_file(file, bdev);
+	if (error)
+		goto out_err;
+
+	old_file = xlo->xlo_backing_file;
+
+	error = -EINVAL;
+
+	/* size of the new backing store needs to be the same */
+	if (get_xloop_size(xlo, file) != get_xloop_size(xlo, old_file))
+		goto out_err;
+
+	/* and ... switch */
+	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
+	blk_mq_freeze_queue(xlo->xlo_queue);
+	mapping_set_gfp_mask(old_file->f_mapping, xlo->old_gfp_mask);
+	xlo->xlo_backing_file = file;
+	xlo->old_gfp_mask = mapping_gfp_mask(file->f_mapping);
+	mapping_set_gfp_mask(file->f_mapping,
+			     xlo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+	xloop_update_dio(xlo);
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
+	xloop_global_unlock(xlo, is_xloop);
+
+	/*
+	 * Flush xloop_validate_file() before fput(), for l->xlo_backing_file
+	 * might be pointing at old_file which might be the last reference.
+	 */
+	if (!is_xloop) {
+		mutex_lock(&xloop_validate_mutex);
+		mutex_unlock(&xloop_validate_mutex);
+	}
+	/*
+	 * We must drop file reference outside of xlo_mutex as dropping
+	 * the file ref can take open_mutex which creates circular locking
+	 * dependency.
+	 */
+	fput(old_file);
+	if (partscan)
+		xloop_reread_partitions(xlo);
+	return 0;
+
+out_err:
+	xloop_global_unlock(xlo, is_xloop);
+out_putf:
+	fput(file);
+	return error;
+}
+
+/* xloop sysfs attributes */
+
+static ssize_t xloop_attr_show(struct device *dev, char *page,
+			      ssize_t (*callback)(struct xloop_device *, char *))
+{
+	struct gendisk *disk = dev_to_disk(dev);
+	struct xloop_device *xlo = disk->private_data;
+
+	return callback(xlo, page);
+}
+
+#define XLOOP_ATTR_RO(_name)						\
+static ssize_t xloop_attr_##_name##_show(struct xloop_device *, char *);	\
+static ssize_t xloop_attr_do_show_##_name(struct device *d,		\
+				struct device_attribute *attr, char *b)	\
+{									\
+	return xloop_attr_show(d, b, xloop_attr_##_name##_show);		\
+}									\
+static struct device_attribute xloop_attr_##_name =			\
+	__ATTR(_name, 0444, xloop_attr_do_show_##_name, NULL);
+
+static ssize_t xloop_attr_backing_file_show(struct xloop_device *xlo, char *buf)
+{
+	ssize_t ret;
+	char *p = NULL;
+
+	spin_lock_irq(&xlo->xlo_lock);
+	if (xlo->xlo_backing_file)
+		p = file_path(xlo->xlo_backing_file, buf, PAGE_SIZE - 1);
+	spin_unlock_irq(&xlo->xlo_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 xloop_attr_file_fmt_type_show(struct xloop_device *xlo, char *buf)
+{
+	ssize_t len = 0;
+
+	len = xloop_file_fmt_print_type(xlo->xlo_fmt->file_fmt_type, buf);
+	len += sprintf(buf + len, "\n");
+
+	return len;
+}
+
+static ssize_t xloop_attr_offset_show(struct xloop_device *xlo, char *buf)
+{
+	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_offset);
+}
+
+static ssize_t xloop_attr_sizelimit_show(struct xloop_device *xlo, char *buf)
+{
+	return sprintf(buf, "%llu\n", (unsigned long long)xlo->xlo_sizelimit);
+}
+
+static ssize_t xloop_attr_autoclear_show(struct xloop_device *xlo, char *buf)
+{
+	int autoclear = (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR);
+
+	return sprintf(buf, "%s\n", autoclear ? "1" : "0");
+}
+
+static ssize_t xloop_attr_partscan_show(struct xloop_device *xlo, char *buf)
+{
+	int partscan = (xlo->xlo_flags & XLO_FLAGS_PARTSCAN);
+
+	return sprintf(buf, "%s\n", partscan ? "1" : "0");
+}
+
+static ssize_t xloop_attr_dio_show(struct xloop_device *xlo, char *buf)
+{
+	int dio = (xlo->xlo_flags & XLO_FLAGS_DIRECT_IO);
+
+	return sprintf(buf, "%s\n", dio ? "1" : "0");
+}
+
+XLOOP_ATTR_RO(backing_file);
+XLOOP_ATTR_RO(file_fmt_type);
+XLOOP_ATTR_RO(offset);
+XLOOP_ATTR_RO(sizelimit);
+XLOOP_ATTR_RO(autoclear);
+XLOOP_ATTR_RO(partscan);
+XLOOP_ATTR_RO(dio);
+
+static struct attribute *xloop_attrs[] = {
+	&xloop_attr_backing_file.attr,
+	&xloop_attr_file_fmt_type.attr,
+	&xloop_attr_offset.attr,
+	&xloop_attr_sizelimit.attr,
+	&xloop_attr_autoclear.attr,
+	&xloop_attr_partscan.attr,
+	&xloop_attr_dio.attr,
+	NULL,
+};
+
+static struct attribute_group xloop_attribute_group = {
+	.name = "xloop",
+	.attrs = xloop_attrs,
+};
+
+static void xloop_sysfs_init(struct xloop_device *xlo)
+{
+	xlo->sysfs_inited = !sysfs_create_group(&disk_to_dev(xlo->xlo_disk)->kobj,
+						&xloop_attribute_group);
+}
+
+static void xloop_sysfs_exit(struct xloop_device *xlo)
+{
+	if (xlo->sysfs_inited)
+		sysfs_remove_group(&disk_to_dev(xlo->xlo_disk)->kobj,
+				   &xloop_attribute_group);
+}
+
+static void xloop_config_discard(struct xloop_device *xlo)
+{
+	struct file *file = xlo->xlo_backing_file;
+	struct inode *inode = file->f_mapping->host;
+	struct request_queue *q = xlo->xlo_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 xloop discards result in blkdev_issue_zeroout(),
+	 * not blkdev_issue_discard(). This maintains consistent behavior with
+	 * file-backed xloop devices: discarded regions read back as zero.
+	 */
+	if (S_ISBLK(inode->i_mode) && !xlo->xlo_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 || xlo->xlo_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;
+}
+
+struct xloop_worker {
+	struct rb_node rb_node;
+	struct work_struct work;
+	struct list_head cmd_list;
+	struct list_head idle_list;
+	struct xloop_device *xlo;
+	struct cgroup_subsys_state *blkcg_css;
+	unsigned long last_ran_at;
+};
+
+static void xloop_workfn(struct work_struct *work);
+static void xloop_rootcg_workfn(struct work_struct *work);
+static void xloop_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 xloop_queue_work(struct xloop_device *xlo, struct xloop_cmd *cmd)
+{
+	struct rb_node **node = &(xlo->worker_tree.rb_node), *parent = NULL;
+	struct xloop_worker *cur_worker, *worker = NULL;
+	struct work_struct *work;
+	struct list_head *cmd_list;
+
+	spin_lock_irq(&xlo->xlo_work_lock);
+
+	if (queue_on_root_worker(cmd->blkcg_css))
+		goto queue_work;
+
+	node = &xlo->worker_tree.rb_node;
+
+	while (*node) {
+		parent = *node;
+		cur_worker = container_of(*node, struct xloop_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 xloop_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, xloop_workfn);
+	INIT_LIST_HEAD(&worker->cmd_list);
+	INIT_LIST_HEAD(&worker->idle_list);
+	worker->xlo = xlo;
+	rb_link_node(&worker->rb_node, parent, node);
+	rb_insert_color(&worker->rb_node, &xlo->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 = &xlo->rootcg_work;
+		cmd_list = &xlo->rootcg_cmd_list;
+	}
+	list_add_tail(&cmd->list_entry, cmd_list);
+	queue_work(xlo->workqueue, work);
+	spin_unlock_irq(&xlo->xlo_work_lock);
+}
+
+static void xloop_update_rotational(struct xloop_device *xlo)
+{
+	struct file *file = xlo->xlo_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 = xlo->xlo_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
+xloop_release_xfer(struct xloop_device *xlo)
+{
+	int err = 0;
+	struct xloop_func_table *xfer = xlo->xlo_encryption;
+
+	if (xfer) {
+		if (xfer->release)
+			err = xfer->release(xlo);
+		xlo->transfer = NULL;
+		xlo->xlo_encryption = NULL;
+		module_put(xfer->owner);
+	}
+	return err;
+}
+
+static int
+xloop_init_xfer(struct xloop_device *xlo, struct xloop_func_table *xfer,
+	       const struct xloop_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(xlo, i);
+		if (err)
+			module_put(owner);
+		else
+			xlo->xlo_encryption = xfer;
+	}
+	return err;
+}
+
+/**
+ * xloop_set_status_from_info - configure device from xloop_info
+ * @xlo: struct xloop_device to configure
+ * @info: struct xloop_info64 to configure the device with
+ *
+ * Configures the xloop device parameters according to the passed
+ * in xloop_info64 configuration.
+ */
+static int
+xloop_set_status_from_info(struct xloop_device *xlo,
+			  const struct xloop_info64 *info)
+{
+	int err;
+	struct xloop_func_table *xfer;
+	kuid_t uid = current_uid();
+
+	if ((unsigned int) info->xlo_encrypt_key_size > XLO_KEY_SIZE)
+		return -EINVAL;
+
+	err = xloop_release_xfer(xlo);
+	if (err)
+		return err;
+
+	if (info->xlo_encrypt_type) {
+		unsigned int type = info->xlo_encrypt_type;
+
+		if (type >= MAX_XLO_CRYPT)
+			return -EINVAL;
+		xfer = xfer_funcs[type];
+		if (xfer == NULL)
+			return -EINVAL;
+	} else
+		xfer = NULL;
+
+	err = xloop_init_xfer(xlo, xfer, info);
+	if (err)
+		return err;
+
+	xlo->xlo_offset = info->xlo_offset;
+	xlo->xlo_sizelimit = info->xlo_sizelimit;
+	memcpy(xlo->xlo_file_name, info->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(xlo->xlo_crypt_name, info->xlo_crypt_name, XLO_NAME_SIZE);
+	xlo->xlo_file_name[XLO_NAME_SIZE-1] = 0;
+	xlo->xlo_crypt_name[XLO_NAME_SIZE-1] = 0;
+
+	if (!xfer)
+		xfer = &none_funcs;
+	xlo->transfer = xfer->transfer;
+	xlo->ioctl = xfer->ioctl;
+
+	xlo->xlo_flags = info->xlo_flags;
+
+	xlo->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
+	xlo->xlo_init[0] = info->xlo_init[0];
+	xlo->xlo_init[1] = info->xlo_init[1];
+	if (info->xlo_encrypt_key_size) {
+		memcpy(xlo->xlo_encrypt_key, info->xlo_encrypt_key,
+		       info->xlo_encrypt_key_size);
+		xlo->xlo_key_owner = uid;
+	}
+
+	return 0;
+}
+
+static int xloop_configure(struct xloop_device *xlo, fmode_t mode,
+			  struct block_device *bdev,
+			  const struct xloop_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_xloop;
+
+	if (!file)
+		return -EBADF;
+	is_xloop = is_xloop_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, xloop_configure);
+		if (error)
+			goto out_putf;
+	}
+
+	error = xloop_global_lock_killable(xlo, is_xloop);
+	if (error)
+		goto out_bdev;
+
+	error = -EBUSY;
+	if (xlo->xlo_state != Xlo_unbound)
+		goto out_unlock;
+
+	error = xloop_validate_file(file, bdev);
+	if (error)
+		goto out_unlock;
+
+	mapping = file->f_mapping;
+	inode = mapping->host;
+
+	if ((config->info.xlo_flags & ~XLOOP_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 = xloop_set_status_from_info(xlo, &config->info);
+	if (error)
+		goto out_unlock;
+
+	if (!(file->f_mode & FMODE_WRITE) || !(mode & FMODE_WRITE) ||
+	    !file->f_op->write_iter)
+		xlo->xlo_flags |= XLO_FLAGS_READ_ONLY;
+
+	xlo->workqueue = alloc_workqueue("xloop%d",
+					WQ_UNBOUND | WQ_FREEZABLE,
+					0,
+					xlo->xlo_number);
+	if (!xlo->workqueue) {
+		error = -ENOMEM;
+		goto out_unlock;
+	}
+
+	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
+	set_disk_ro(xlo->xlo_disk, (xlo->xlo_flags & XLO_FLAGS_READ_ONLY) != 0);
+
+	INIT_WORK(&xlo->rootcg_work, xloop_rootcg_workfn);
+	INIT_LIST_HEAD(&xlo->rootcg_cmd_list);
+	INIT_LIST_HEAD(&xlo->idle_worker_list);
+	xlo->worker_tree = RB_ROOT;
+	timer_setup(&xlo->timer, xloop_free_idle_workers,
+		TIMER_DEFERRABLE);
+	xlo->use_dio = xlo->xlo_flags & XLO_FLAGS_DIRECT_IO;
+	xlo->xlo_device = bdev;
+	xlo->xlo_backing_file = file;
+	xlo->old_gfp_mask = mapping_gfp_mask(mapping);
+	mapping_set_gfp_mask(mapping, xlo->old_gfp_mask & ~(__GFP_IO|__GFP_FS));
+
+	error = xloop_file_fmt_init(xlo->xlo_fmt, config->info.xlo_file_fmt_type);
+	if (error)
+		goto out_unlock;
+
+	if (!(xlo->xlo_flags & XLO_FLAGS_READ_ONLY) && file->f_op->fsync)
+		blk_queue_write_cache(xlo->xlo_queue, true, false);
+
+	if (config->block_size)
+		bsize = config->block_size;
+	else if ((xlo->xlo_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(xlo->xlo_queue, bsize);
+	blk_queue_physical_block_size(xlo->xlo_queue, bsize);
+	blk_queue_io_min(xlo->xlo_queue, bsize);
+
+	xloop_config_discard(xlo);
+	xloop_update_rotational(xlo);
+	xloop_update_dio(xlo);
+	xloop_sysfs_init(xlo);
+
+	size = get_xloop_size(xlo, file);
+	xloop_set_size(xlo, size);
+
+	/* Order wrt reading xlo_state in xloop_validate_file(). */
+	wmb();
+
+	xlo->xlo_state = Xlo_bound;
+	if (part_shift)
+		xlo->xlo_flags |= XLO_FLAGS_PARTSCAN;
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN;
+	if (partscan)
+		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+
+	xloop_global_unlock(xlo, is_xloop);
+	if (partscan)
+		xloop_reread_partitions(xlo);
+	if (!(mode & FMODE_EXCL))
+		bd_abort_claiming(bdev, xloop_configure);
+	return 0;
+
+out_unlock:
+	xloop_global_unlock(xlo, is_xloop);
+out_bdev:
+	if (!(mode & FMODE_EXCL))
+		bd_abort_claiming(bdev, xloop_configure);
+out_putf:
+	fput(file);
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+	return error;
+}
+
+static int __xloop_clr_fd(struct xloop_device *xlo, bool release)
+{
+	struct file *filp = NULL;
+	gfp_t gfp = xlo->old_gfp_mask;
+	struct block_device *bdev = xlo->xlo_device;
+	int err = 0;
+	bool partscan = false;
+	int xlo_number;
+	struct xloop_worker *pos, *worker;
+
+	/*
+	 * Flush xloop_configure() and xloop_change_fd(). It is acceptable for
+	 * xloop_validate_file() to succeed, for actual clear operation has not
+	 * started yet.
+	 */
+	mutex_lock(&xloop_validate_mutex);
+	mutex_unlock(&xloop_validate_mutex);
+	/*
+	 * xloop_validate_file() now fails because l->xlo_state != Xlo_bound
+	 * became visible.
+	 */
+
+	mutex_lock(&xlo->xlo_mutex);
+	if (WARN_ON_ONCE(xlo->xlo_state != Xlo_rundown)) {
+		err = -ENXIO;
+		goto out_unlock;
+	}
+
+	filp = xlo->xlo_backing_file;
+	if (filp == NULL) {
+		err = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (test_bit(QUEUE_FLAG_WC, &xlo->xlo_queue->queue_flags))
+		blk_queue_write_cache(xlo->xlo_queue, false, false);
+
+	/* freeze request queue during the transition */
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	xloop_file_fmt_exit(xlo->xlo_fmt);
+
+	destroy_workqueue(xlo->workqueue);
+	spin_lock_irq(&xlo->xlo_work_lock);
+	list_for_each_entry_safe(worker, pos, &xlo->idle_worker_list,
+				idle_list) {
+		list_del(&worker->idle_list);
+		rb_erase(&worker->rb_node, &xlo->worker_tree);
+		css_put(worker->blkcg_css);
+		kfree(worker);
+	}
+	spin_unlock_irq(&xlo->xlo_work_lock);
+	del_timer_sync(&xlo->timer);
+
+	spin_lock_irq(&xlo->xlo_lock);
+	xlo->xlo_backing_file = NULL;
+	spin_unlock_irq(&xlo->xlo_lock);
+
+	xloop_release_xfer(xlo);
+	xlo->transfer = NULL;
+	xlo->ioctl = NULL;
+	xlo->xlo_device = NULL;
+	xlo->xlo_encryption = NULL;
+	xlo->xlo_offset = 0;
+	xlo->xlo_sizelimit = 0;
+	xlo->xlo_encrypt_key_size = 0;
+	memset(xlo->xlo_encrypt_key, 0, XLO_KEY_SIZE);
+	memset(xlo->xlo_crypt_name, 0, XLO_NAME_SIZE);
+	memset(xlo->xlo_file_name, 0, XLO_NAME_SIZE);
+	blk_queue_logical_block_size(xlo->xlo_queue, 512);
+	blk_queue_physical_block_size(xlo->xlo_queue, 512);
+	blk_queue_io_min(xlo->xlo_queue, 512);
+	if (bdev) {
+		invalidate_bdev(bdev);
+		bdev->bd_inode->i_mapping->wb_err = 0;
+	}
+	set_capacity(xlo->xlo_disk, 0);
+	xloop_sysfs_exit(xlo);
+	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(xlo->xlo_queue);
+
+	partscan = xlo->xlo_flags & XLO_FLAGS_PARTSCAN && bdev;
+	xlo_number = xlo->xlo_number;
+	disk_force_media_change(xlo->xlo_disk, DISK_EVENT_MEDIA_CHANGE);
+out_unlock:
+	mutex_unlock(&xlo->xlo_mutex);
+	if (partscan) {
+		/*
+		 * open_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, xlo_refcnt
+		 * must be at least one and it can only become zero when the
+		 * current holder is released.
+		 */
+		if (!release)
+			mutex_lock(&xlo->xlo_disk->open_mutex);
+		err = bdev_disk_changed(xlo->xlo_disk, false);
+		if (!release)
+			mutex_unlock(&xlo->xlo_disk->open_mutex);
+		if (err)
+			dev_warn(xloop_device_to_dev(xlo),
+				"partition scan of xloop%d failed (rc=%d)\n",
+				xlo_number, err);
+		/* Device is gone, no point in returning error */
+		err = 0;
+	}
+
+	/*
+	 * xlo->xlo_state is set to Xlo_unbound here after above partscan has
+	 * finished.
+	 *
+	 * There cannot be anybody else entering __xloop_clr_fd() as
+	 * xlo->xlo_backing_file is already cleared and Xlo_rundown state
+	 * protects us from all the other places trying to change the 'xlo'
+	 * device.
+	 */
+	mutex_lock(&xlo->xlo_mutex);
+	xlo->xlo_flags = 0;
+	if (!part_shift)
+		xlo->xlo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+	xlo->xlo_state = Xlo_unbound;
+	mutex_unlock(&xlo->xlo_mutex);
+
+	/*
+	 * Need not hold xlo_mutex to fput backing file. Calling fput holding
+	 * xlo_mutex triggers a circular lock dependency possibility warning as
+	 * fput can take open_mutex which is usually taken before xlo_mutex.
+	 */
+	if (filp)
+		fput(filp);
+	return err;
+}
+
+static int xloop_clr_fd(struct xloop_device *xlo)
+{
+	int err;
+
+	err = mutex_lock_killable(&xlo->xlo_mutex);
+	if (err)
+		return err;
+	if (xlo->xlo_state != Xlo_bound) {
+		mutex_unlock(&xlo->xlo_mutex);
+		return -ENXIO;
+	}
+	/*
+	 * If we've explicitly asked to tear down the xloop 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 xloopback device whenever they appear. xfstests is notorious for
+	 * failing tests because blkid via udev races with a xlosetup
+	 * <dev>/do something like mkfs/xlosetup -d <dev> causing the xlosetup -d
+	 * command to fail with EBUSY.
+	 */
+	if (atomic_read(&xlo->xlo_refcnt) > 1) {
+		xlo->xlo_flags |= XLO_FLAGS_AUTOCLEAR;
+		mutex_unlock(&xlo->xlo_mutex);
+		return 0;
+	}
+	xlo->xlo_state = Xlo_rundown;
+	mutex_unlock(&xlo->xlo_mutex);
+
+	return __xloop_clr_fd(xlo, false);
+}
+
+static int
+xloop_set_status(struct xloop_device *xlo, const struct xloop_info64 *info)
+{
+	int err;
+	kuid_t uid = current_uid();
+	int prev_xlo_flags;
+	bool partscan = false;
+	bool size_changed = false;
+
+	err = mutex_lock_killable(&xlo->xlo_mutex);
+	if (err)
+		return err;
+	if (xlo->xlo_encrypt_key_size &&
+	    !uid_eq(xlo->xlo_key_owner, uid) &&
+	    !capable(CAP_SYS_ADMIN)) {
+		err = -EPERM;
+		goto out_unlock;
+	}
+	if (xlo->xlo_state != Xlo_bound) {
+		err = -ENXIO;
+		goto out_unlock;
+	}
+
+	if (xlo->xlo_offset != info->xlo_offset ||
+	    xlo->xlo_sizelimit != info->xlo_sizelimit) {
+		size_changed = true;
+		sync_blockdev(xlo->xlo_device);
+		invalidate_bdev(xlo->xlo_device);
+	}
+
+	/* I/O need to be drained during transfer transition */
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	if (size_changed && xlo->xlo_device->bd_inode->i_mapping->nrpages) {
+		/* If any pages were dirtied after invalidate_bdev(), try again */
+		err = -EAGAIN;
+		dev_warn(xloop_device_to_dev(xlo),
+			"xloop%d (%s) has still dirty pages (nrpages=%lu)\n",
+			xlo->xlo_number, xlo->xlo_file_name,
+			xlo->xlo_device->bd_inode->i_mapping->nrpages);
+		goto out_unfreeze;
+	}
+
+	prev_xlo_flags = xlo->xlo_flags;
+
+	err = xloop_set_status_from_info(xlo, info);
+	if (err)
+		goto out_unfreeze;
+
+	/* Mask out flags that can't be set using XLOOP_SET_STATUS. */
+	xlo->xlo_flags &= XLOOP_SET_STATUS_SETTABLE_FLAGS;
+	/* For those flags, use the previous values instead */
+	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_SETTABLE_FLAGS;
+	/* For flags that can't be cleared, use previous values too */
+	xlo->xlo_flags |= prev_xlo_flags & ~XLOOP_SET_STATUS_CLEARABLE_FLAGS;
+
+	if (xlo->xlo_fmt->file_fmt_type != info->xlo_file_fmt_type) {
+		/* xloop file format has changed, so change file format driver */
+		err = xloop_file_fmt_change(xlo->xlo_fmt, info->xlo_file_fmt_type);
+		if (err)
+			goto out_unfreeze;
+
+		/* After change of the file format, recalculate the capacity of the xloop device. */
+		size_changed = true;
+	}
+
+	if (size_changed) {
+		loff_t new_size = get_xloop_size(xlo, xlo->xlo_backing_file);
+
+		xloop_set_size(xlo, new_size);
+	}
+
+	xloop_config_discard(xlo);
+
+	/* update dio if xlo_offset or transfer is changed */
+	__xloop_update_dio(xlo, xlo->use_dio);
+
+out_unfreeze:
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+
+	if (!err && (xlo->xlo_flags & XLO_FLAGS_PARTSCAN) &&
+	     !(prev_xlo_flags & XLO_FLAGS_PARTSCAN)) {
+		xlo->xlo_disk->flags &= ~GENHD_FL_NO_PART_SCAN;
+		partscan = true;
+	}
+out_unlock:
+	mutex_unlock(&xlo->xlo_mutex);
+	if (partscan)
+		xloop_reread_partitions(xlo);
+
+	return err;
+}
+
+static int
+xloop_get_status(struct xloop_device *xlo, struct xloop_info64 *info)
+{
+	struct path path;
+	struct kstat stat;
+	int ret;
+
+	ret = mutex_lock_killable(&xlo->xlo_mutex);
+	if (ret)
+		return ret;
+	if (xlo->xlo_state != Xlo_bound) {
+		mutex_unlock(&xlo->xlo_mutex);
+		return -ENXIO;
+	}
+
+	memset(info, 0, sizeof(*info));
+	info->xlo_number = xlo->xlo_number;
+	info->xlo_offset = xlo->xlo_offset;
+	info->xlo_sizelimit = xlo->xlo_sizelimit;
+	info->xlo_flags = xlo->xlo_flags;
+	memcpy(info->xlo_file_name, xlo->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info->xlo_crypt_name, xlo->xlo_crypt_name, XLO_NAME_SIZE);
+	info->xlo_encrypt_type =
+		xlo->xlo_encryption ? xlo->xlo_encryption->number : 0;
+	if (xlo->xlo_encrypt_key_size && capable(CAP_SYS_ADMIN)) {
+		info->xlo_encrypt_key_size = xlo->xlo_encrypt_key_size;
+		memcpy(info->xlo_encrypt_key, xlo->xlo_encrypt_key,
+		       xlo->xlo_encrypt_key_size);
+	}
+
+	/* Drop xlo_mutex while we call into the filesystem. */
+	path = xlo->xlo_backing_file->f_path;
+	path_get(&path);
+	mutex_unlock(&xlo->xlo_mutex);
+	ret = vfs_getattr(&path, &stat, STATX_INO, AT_STATX_SYNC_AS_STAT);
+	if (!ret) {
+		info->xlo_device = huge_encode_dev(stat.dev);
+		info->xlo_inode = stat.ino;
+		info->xlo_rdevice = huge_encode_dev(stat.rdev);
+	}
+	path_put(&path);
+	return ret;
+}
+
+static void
+xloop_info64_from_old(const struct xloop_info *info, struct xloop_info64 *info64)
+{
+	memset(info64, 0, sizeof(*info64));
+	info64->xlo_number = info->xlo_number;
+	info64->xlo_device = info->xlo_device;
+	info64->xlo_inode = info->xlo_inode;
+	info64->xlo_rdevice = info->xlo_rdevice;
+	info64->xlo_offset = info->xlo_offset;
+	info64->xlo_sizelimit = 0;
+	info64->xlo_encrypt_type = info->xlo_encrypt_type;
+	info64->xlo_encrypt_key_size = info->xlo_encrypt_key_size;
+	info64->xlo_flags = info->xlo_flags;
+	info64->xlo_init[0] = info->xlo_init[0];
+	info64->xlo_init[1] = info->xlo_init[1];
+	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info64->xlo_crypt_name, info->xlo_name, XLO_NAME_SIZE);
+	else
+		memcpy(info64->xlo_file_name, info->xlo_name, XLO_NAME_SIZE);
+	memcpy(info64->xlo_encrypt_key, info->xlo_encrypt_key, XLO_KEY_SIZE);
+}
+
+static int
+xloop_info64_to_old(const struct xloop_info64 *info64, struct xloop_info *info)
+{
+	memset(info, 0, sizeof(*info));
+	info->xlo_number = info64->xlo_number;
+	info->xlo_device = info64->xlo_device;
+	info->xlo_inode = info64->xlo_inode;
+	info->xlo_rdevice = info64->xlo_rdevice;
+	info->xlo_offset = info64->xlo_offset;
+	info->xlo_encrypt_type = info64->xlo_encrypt_type;
+	info->xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
+	info->xlo_flags = info64->xlo_flags;
+	info->xlo_init[0] = info64->xlo_init[0];
+	info->xlo_init[1] = info64->xlo_init[1];
+	if (info->xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info->xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
+	else
+		memcpy(info->xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info->xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
+
+	/* error in case values were truncated */
+	if (info->xlo_device != info64->xlo_device ||
+	    info->xlo_rdevice != info64->xlo_rdevice ||
+	    info->xlo_inode != info64->xlo_inode ||
+	    info->xlo_offset != info64->xlo_offset)
+		return -EOVERFLOW;
+
+	return 0;
+}
+
+static int
+xloop_set_status_old(struct xloop_device *xlo, const struct xloop_info __user *arg)
+{
+	struct xloop_info info;
+	struct xloop_info64 info64;
+
+	if (copy_from_user(&info, arg, sizeof(struct xloop_info)))
+		return -EFAULT;
+	xloop_info64_from_old(&info, &info64);
+	return xloop_set_status(xlo, &info64);
+}
+
+static int
+xloop_set_status64(struct xloop_device *xlo, const struct xloop_info64 __user *arg)
+{
+	struct xloop_info64 info64;
+
+	if (copy_from_user(&info64, arg, sizeof(struct xloop_info64)))
+		return -EFAULT;
+	return xloop_set_status(xlo, &info64);
+}
+
+static int
+xloop_get_status_old(struct xloop_device *xlo, struct xloop_info __user *arg)
+{
+	struct xloop_info info;
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err)
+		err = xloop_info64_to_old(&info64, &info);
+	if (!err && copy_to_user(arg, &info, sizeof(info)))
+		err = -EFAULT;
+
+	return err;
+}
+
+static int
+xloop_get_status64(struct xloop_device *xlo, struct xloop_info64 __user *arg)
+{
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err && copy_to_user(arg, &info64, sizeof(info64)))
+		err = -EFAULT;
+
+	return err;
+}
+
+static int xloop_set_capacity(struct xloop_device *xlo)
+{
+	loff_t size;
+
+	if (unlikely(xlo->xlo_state != Xlo_bound))
+		return -ENXIO;
+
+	size = get_xloop_size(xlo, xlo->xlo_backing_file);
+	xloop_set_size(xlo, size);
+
+	return 0;
+}
+
+static int xloop_set_dio(struct xloop_device *xlo, unsigned long arg)
+{
+	int error = -ENXIO;
+
+	if (xlo->xlo_state != Xlo_bound)
+		goto out;
+
+	__xloop_update_dio(xlo, !!arg);
+	if (xlo->use_dio == !!arg)
+		return 0;
+	error = -EINVAL;
+ out:
+	return error;
+}
+
+static int xloop_set_block_size(struct xloop_device *xlo, unsigned long arg)
+{
+	int err = 0;
+
+	if (xlo->xlo_state != Xlo_bound)
+		return -ENXIO;
+
+	err = blk_validate_block_size(arg);
+	if (err)
+		return err;
+
+	if (xlo->xlo_queue->limits.logical_block_size == arg)
+		return 0;
+
+	sync_blockdev(xlo->xlo_device);
+	invalidate_bdev(xlo->xlo_device);
+
+	blk_mq_freeze_queue(xlo->xlo_queue);
+
+	/* invalidate_bdev should have truncated all the pages */
+	if (xlo->xlo_device->bd_inode->i_mapping->nrpages) {
+		err = -EAGAIN;
+		dev_warn(xloop_device_to_dev(xlo),
+			"xloop%d (%s) has still dirty pages (nrpages=%lu)\n",
+			xlo->xlo_number, xlo->xlo_file_name,
+			xlo->xlo_device->bd_inode->i_mapping->nrpages);
+		goto out_unfreeze;
+	}
+
+	blk_queue_logical_block_size(xlo->xlo_queue, arg);
+	blk_queue_physical_block_size(xlo->xlo_queue, arg);
+	blk_queue_io_min(xlo->xlo_queue, arg);
+	xloop_update_dio(xlo);
+out_unfreeze:
+	blk_mq_unfreeze_queue(xlo->xlo_queue);
+
+	return err;
+}
+
+static int xlo_simple_ioctl(struct xloop_device *xlo, unsigned int cmd,
+			   unsigned long arg)
+{
+	int err;
+
+	err = mutex_lock_killable(&xlo->xlo_mutex);
+	if (err)
+		return err;
+	switch (cmd) {
+	case XLOOP_SET_CAPACITY:
+		err = xloop_set_capacity(xlo);
+		break;
+	case XLOOP_SET_DIRECT_IO:
+		err = xloop_set_dio(xlo, arg);
+		break;
+	case XLOOP_SET_BLOCK_SIZE:
+		err = xloop_set_block_size(xlo, arg);
+		break;
+	default:
+		err = xlo->ioctl ? xlo->ioctl(xlo, cmd, arg) : -EINVAL;
+	}
+	mutex_unlock(&xlo->xlo_mutex);
+	return err;
+}
+
+static int xlo_ioctl(struct block_device *bdev, fmode_t mode,
+	unsigned int cmd, unsigned long arg)
+{
+	struct xloop_device *xlo = bdev->bd_disk->private_data;
+	void __user *argp = (void __user *) arg;
+	int err;
+
+	switch (cmd) {
+	case XLOOP_SET_FD: {
+		/*
+		 * Legacy case - pass in a zeroed out struct xloop_config with
+		 * only the file descriptor set , which corresponds with the
+		 * default parameters we'd have used otherwise.
+		 */
+		struct xloop_config config;
+
+		memset(&config, 0, sizeof(config));
+		config.fd = arg;
+
+		return xloop_configure(xlo, mode, bdev, &config);
+	}
+	case XLOOP_CONFIGURE: {
+		struct xloop_config config;
+
+		if (copy_from_user(&config, argp, sizeof(config)))
+			return -EFAULT;
+
+		return xloop_configure(xlo, mode, bdev, &config);
+	}
+	case XLOOP_CHANGE_FD:
+		return xloop_change_fd(xlo, bdev, arg);
+	case XLOOP_CLR_FD:
+		return xloop_clr_fd(xlo);
+	case XLOOP_SET_STATUS:
+		err = -EPERM;
+		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+			err = xloop_set_status_old(xlo, argp);
+		break;
+	case XLOOP_GET_STATUS:
+		return xloop_get_status_old(xlo, argp);
+	case XLOOP_SET_STATUS64:
+		err = -EPERM;
+		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))
+			err = xloop_set_status64(xlo, argp);
+		break;
+	case XLOOP_GET_STATUS64:
+		return xloop_get_status64(xlo, argp);
+	case XLOOP_SET_CAPACITY:
+	case XLOOP_SET_DIRECT_IO:
+	case XLOOP_SET_BLOCK_SIZE:
+		if (!(mode & FMODE_WRITE) && !capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		fallthrough;
+	default:
+		err = xlo_simple_ioctl(xlo, cmd, arg);
+		break;
+	}
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+struct compat_xloop_info {
+	compat_int_t	xlo_number;      /* ioctl r/o */
+	compat_dev_t	xlo_device;      /* ioctl r/o */
+	compat_ulong_t	xlo_inode;       /* ioctl r/o */
+	compat_dev_t	xlo_rdevice;     /* ioctl r/o */
+	compat_int_t	xlo_offset;
+	compat_int_t	xlo_encrypt_type;
+	compat_int_t	xlo_encrypt_key_size;    /* ioctl w/o */
+	compat_int_t	xlo_flags;       /* ioctl r/o */
+	char		xlo_name[XLO_NAME_SIZE];
+	unsigned char	xlo_encrypt_key[XLO_KEY_SIZE]; /* ioctl w/o */
+	compat_ulong_t	xlo_init[2];
+	char		reserved[4];
+};
+
+/*
+ * Transfer 32-bit compatibility structure in userspace to 64-bit xloop info
+ * - noinlined to reduce stack space usage in main part of driver
+ */
+static noinline int
+xloop_info64_from_compat(const struct compat_xloop_info __user *arg,
+			struct xloop_info64 *info64)
+{
+	struct compat_xloop_info info;
+
+	if (copy_from_user(&info, arg, sizeof(info)))
+		return -EFAULT;
+
+	memset(info64, 0, sizeof(*info64));
+	info64->xlo_number = info.xlo_number;
+	info64->xlo_device = info.xlo_device;
+	info64->xlo_inode = info.xlo_inode;
+	info64->xlo_rdevice = info.xlo_rdevice;
+	info64->xlo_offset = info.xlo_offset;
+	info64->xlo_sizelimit = 0;
+	info64->xlo_encrypt_type = info.xlo_encrypt_type;
+	info64->xlo_encrypt_key_size = info.xlo_encrypt_key_size;
+	info64->xlo_flags = info.xlo_flags;
+	info64->xlo_init[0] = info.xlo_init[0];
+	info64->xlo_init[1] = info.xlo_init[1];
+	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info64->xlo_crypt_name, info.xlo_name, XLO_NAME_SIZE);
+	else
+		memcpy(info64->xlo_file_name, info.xlo_name, XLO_NAME_SIZE);
+	memcpy(info64->xlo_encrypt_key, info.xlo_encrypt_key, XLO_KEY_SIZE);
+	return 0;
+}
+
+/*
+ * Transfer 64-bit xloop info to 32-bit compatibility structure in userspace
+ * - noinlined to reduce stack space usage in main part of driver
+ */
+static noinline int
+xloop_info64_to_compat(const struct xloop_info64 *info64,
+		      struct compat_xloop_info __user *arg)
+{
+	struct compat_xloop_info info;
+
+	memset(&info, 0, sizeof(info));
+	info.xlo_number = info64->xlo_number;
+	info.xlo_device = info64->xlo_device;
+	info.xlo_inode = info64->xlo_inode;
+	info.xlo_rdevice = info64->xlo_rdevice;
+	info.xlo_offset = info64->xlo_offset;
+	info.xlo_encrypt_type = info64->xlo_encrypt_type;
+	info.xlo_encrypt_key_size = info64->xlo_encrypt_key_size;
+	info.xlo_flags = info64->xlo_flags;
+	info.xlo_init[0] = info64->xlo_init[0];
+	info.xlo_init[1] = info64->xlo_init[1];
+	if (info.xlo_encrypt_type == XLO_CRYPT_CRYPTOAPI)
+		memcpy(info.xlo_name, info64->xlo_crypt_name, XLO_NAME_SIZE);
+	else
+		memcpy(info.xlo_name, info64->xlo_file_name, XLO_NAME_SIZE);
+	memcpy(info.xlo_encrypt_key, info64->xlo_encrypt_key, XLO_KEY_SIZE);
+
+	/* error in case values were truncated */
+	if (info.xlo_device != info64->xlo_device ||
+	    info.xlo_rdevice != info64->xlo_rdevice ||
+	    info.xlo_inode != info64->xlo_inode ||
+	    info.xlo_offset != info64->xlo_offset ||
+	    info.xlo_init[0] != info64->xlo_init[0] ||
+	    info.xlo_init[1] != info64->xlo_init[1])
+		return -EOVERFLOW;
+
+	if (copy_to_user(arg, &info, sizeof(info)))
+		return -EFAULT;
+	return 0;
+}
+
+static int
+xloop_set_status_compat(struct xloop_device *xlo,
+		       const struct compat_xloop_info __user *arg)
+{
+	struct xloop_info64 info64;
+	int ret;
+
+	ret = xloop_info64_from_compat(arg, &info64);
+	if (ret < 0)
+		return ret;
+	return xloop_set_status(xlo, &info64);
+}
+
+static int
+xloop_get_status_compat(struct xloop_device *xlo,
+		       struct compat_xloop_info __user *arg)
+{
+	struct xloop_info64 info64;
+	int err;
+
+	if (!arg)
+		return -EINVAL;
+	err = xloop_get_status(xlo, &info64);
+	if (!err)
+		err = xloop_info64_to_compat(&info64, arg);
+	return err;
+}
+
+static int xlo_compat_ioctl(struct block_device *bdev, fmode_t mode,
+			   unsigned int cmd, unsigned long arg)
+{
+	struct xloop_device *xlo = bdev->bd_disk->private_data;
+	int err;
+
+	switch (cmd) {
+	case XLOOP_SET_STATUS:
+		err = xloop_set_status_compat(xlo,
+			     (const struct compat_xloop_info __user *)arg);
+		break;
+	case XLOOP_GET_STATUS:
+		err = xloop_get_status_compat(xlo,
+				     (struct compat_xloop_info __user *)arg);
+		break;
+	case XLOOP_SET_CAPACITY:
+	case XLOOP_CLR_FD:
+	case XLOOP_GET_STATUS64:
+	case XLOOP_SET_STATUS64:
+	case XLOOP_CONFIGURE:
+		arg = (unsigned long) compat_ptr(arg);
+		fallthrough;
+	case XLOOP_SET_FD:
+	case XLOOP_CHANGE_FD:
+	case XLOOP_SET_BLOCK_SIZE:
+	case XLOOP_SET_DIRECT_IO:
+		err = xlo_ioctl(bdev, mode, cmd, arg);
+		break;
+	default:
+		err = -ENOIOCTLCMD;
+		break;
+	}
+	return err;
+}
+#endif
+
+static int xlo_open(struct block_device *bdev, fmode_t mode)
+{
+	struct xloop_device *xlo = bdev->bd_disk->private_data;
+	int err;
+
+	err = mutex_lock_killable(&xlo->xlo_mutex);
+	if (err)
+		return err;
+	if (xlo->xlo_state == Xlo_deleting)
+		err = -ENXIO;
+	else
+		atomic_inc(&xlo->xlo_refcnt);
+	mutex_unlock(&xlo->xlo_mutex);
+	return err;
+}
+
+static void xlo_release(struct gendisk *disk, fmode_t mode)
+{
+	struct xloop_device *xlo = disk->private_data;
+
+	mutex_lock(&xlo->xlo_mutex);
+	if (atomic_dec_return(&xlo->xlo_refcnt))
+		goto out_unlock;
+
+	if (xlo->xlo_flags & XLO_FLAGS_AUTOCLEAR) {
+		if (xlo->xlo_state != Xlo_bound)
+			goto out_unlock;
+		xlo->xlo_state = Xlo_rundown;
+		mutex_unlock(&xlo->xlo_mutex);
+		/*
+		 * In autoclear mode, stop the xloop thread
+		 * and remove configuration after last close.
+		 */
+		__xloop_clr_fd(xlo, true);
+		return;
+	} else if (xlo->xlo_state == Xlo_bound) {
+		/*
+		 * Otherwise keep thread (if running) and config,
+		 * but flush possible ongoing bios in thread.
+		 */
+		blk_mq_freeze_queue(xlo->xlo_queue);
+		blk_mq_unfreeze_queue(xlo->xlo_queue);
+	}
+
+out_unlock:
+	mutex_unlock(&xlo->xlo_mutex);
+}
+
+static const struct block_device_operations xlo_fops = {
+	.owner =	THIS_MODULE,
+	.open =		xlo_open,
+	.release =	xlo_release,
+	.ioctl =	xlo_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	xlo_compat_ioctl,
+#endif
+};
+
+/*
+ * And now the modules code and kernel interface.
+ */
+static int max_xloop;
+module_param(max_xloop, int, 0444);
+MODULE_PARM_DESC(max_xloop, "Maximum number of xloop devices");
+module_param(max_part, int, 0444);
+MODULE_PARM_DESC(max_part, "Maximum number of partitions per xloop device");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Manuel Bentele <development@manuel-bentele.de>");
+MODULE_VERSION(XLOOP_VERSION);
+MODULE_ALIAS_BLOCKDEV_MAJOR(XLOOP_MAJOR);
+
+int xloop_register_transfer(struct xloop_func_table *funcs)
+{
+	unsigned int n = funcs->number;
+
+	if (n >= MAX_XLO_CRYPT || xfer_funcs[n])
+		return -EINVAL;
+	xfer_funcs[n] = funcs;
+	return 0;
+}
+EXPORT_SYMBOL(xloop_register_transfer);
+
+int xloop_unregister_transfer(int number)
+{
+	unsigned int n = number;
+	struct xloop_func_table *xfer = xfer_funcs[n];
+
+	if (n == 0 || n >= MAX_XLO_CRYPT || xfer == NULL)
+		return -EINVAL;
+	/*
+	 * This function is called from only cleanup_cryptoxloop().
+	 * Given that each xloop device that has a transfer enabled holds a
+	 * reference to the module implementing it we should never get here
+	 * with a transfer that is set (unless forced module unloading is
+	 * requested). Thus, check module's refcount and warn if this is
+	 * not a clean unloading.
+	 */
+#ifdef CONFIG_MODULE_UNLOAD
+	if (xfer->owner && module_refcount(xfer->owner) != -1)
+		pr_err("Danger! Unregistering an in use transfer function.\n");
+#endif
+
+	xfer_funcs[n] = NULL;
+	return 0;
+}
+EXPORT_SYMBOL(xloop_unregister_transfer);
+
+static blk_status_t xloop_queue_rq(struct blk_mq_hw_ctx *hctx,
+		const struct blk_mq_queue_data *bd)
+{
+	struct request *rq = bd->rq;
+	struct xloop_cmd *cmd = blk_mq_rq_to_pdu(rq);
+	struct xloop_device *xlo = rq->q->queuedata;
+
+	blk_mq_start_request(rq);
+
+	if (xlo->xlo_state != Xlo_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 = xlo->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
+	xloop_queue_work(xlo, cmd);
+
+	return BLK_STS_OK;
+}
+
+static void xloop_handle_cmd(struct xloop_cmd *cmd)
+{
+	struct request *rq = blk_mq_rq_from_pdu(cmd);
+	const bool write = op_is_write(req_op(rq));
+	struct xloop_device *xlo = rq->q->queuedata;
+	int ret = 0;
+	struct mem_cgroup *old_memcg = NULL;
+
+	if (write && (xlo->xlo_flags & XLO_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(xlo, 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 xloop_set_timer(struct xloop_device *xlo)
+{
+	timer_reduce(&xlo->timer, jiffies + XLOOP_IDLE_WORKER_TIMEOUT);
+}
+
+static void xloop_process_work(struct xloop_worker *worker,
+			struct list_head *cmd_list, struct xloop_device *xlo)
+{
+	int orig_flags = current->flags;
+	struct xloop_cmd *cmd;
+
+	current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
+	spin_lock_irq(&xlo->xlo_work_lock);
+	while (!list_empty(cmd_list)) {
+		cmd = container_of(
+			cmd_list->next, struct xloop_cmd, list_entry);
+		list_del(cmd_list->next);
+		spin_unlock_irq(&xlo->xlo_work_lock);
+
+		xloop_handle_cmd(cmd);
+		cond_resched();
+
+		spin_lock_irq(&xlo->xlo_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, &xlo->idle_worker_list);
+		xloop_set_timer(xlo);
+	}
+	spin_unlock_irq(&xlo->xlo_work_lock);
+	current->flags = orig_flags;
+}
+
+static void xloop_workfn(struct work_struct *work)
+{
+	struct xloop_worker *worker =
+		container_of(work, struct xloop_worker, work);
+	xloop_process_work(worker, &worker->cmd_list, worker->xlo);
+}
+
+static void xloop_rootcg_workfn(struct work_struct *work)
+{
+	struct xloop_device *xlo =
+		container_of(work, struct xloop_device, rootcg_work);
+	xloop_process_work(NULL, &xlo->rootcg_cmd_list, xlo);
+}
+
+static void xloop_free_idle_workers(struct timer_list *timer)
+{
+	struct xloop_device *xlo = container_of(timer, struct xloop_device, timer);
+	struct xloop_worker *pos, *worker;
+
+	spin_lock_irq(&xlo->xlo_work_lock);
+	list_for_each_entry_safe(worker, pos, &xlo->idle_worker_list,
+				idle_list) {
+		if (time_is_after_jiffies(worker->last_ran_at +
+						XLOOP_IDLE_WORKER_TIMEOUT))
+			break;
+		list_del(&worker->idle_list);
+		rb_erase(&worker->rb_node, &xlo->worker_tree);
+		css_put(worker->blkcg_css);
+		kfree(worker);
+	}
+	if (!list_empty(&xlo->idle_worker_list))
+		xloop_set_timer(xlo);
+	spin_unlock_irq(&xlo->xlo_work_lock);
+}
+
+static const struct blk_mq_ops xloop_mq_ops = {
+	.queue_rq       = xloop_queue_rq,
+	.complete	= xlo_complete_rq,
+};
+
+static struct dentry *xloop_dbgfs_dir;
+
+static int xloop_add(int i)
+{
+	struct xloop_device *xlo;
+	struct gendisk *disk;
+	int err;
+
+	err = -ENOMEM;
+	xlo = kzalloc(sizeof(*xlo), GFP_KERNEL);
+	if (!xlo)
+		goto out;
+	xlo->xlo_state = Xlo_unbound;
+
+	err = mutex_lock_killable(&xloop_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(&xloop_index_idr, xlo, i, i + 1, GFP_KERNEL);
+		if (err == -ENOSPC)
+			err = -EEXIST;
+	} else {
+		err = idr_alloc(&xloop_index_idr, xlo, 0, 0, GFP_KERNEL);
+	}
+	mutex_unlock(&xloop_ctl_mutex);
+	if (err < 0)
+		goto out_free_dev;
+	i = err;
+
+	err = -ENOMEM;
+	xlo->tag_set.ops = &xloop_mq_ops;
+	xlo->tag_set.nr_hw_queues = 1;
+	xlo->tag_set.queue_depth = 128;
+	xlo->tag_set.numa_node = NUMA_NO_NODE;
+	xlo->tag_set.cmd_size = sizeof(struct xloop_cmd);
+	xlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING |
+		BLK_MQ_F_NO_SCHED_BY_DEFAULT;
+	xlo->tag_set.driver_data = xlo;
+
+	err = blk_mq_alloc_tag_set(&xlo->tag_set);
+	if (err)
+		goto out_free_idr;
+
+	disk = xlo->xlo_disk = blk_mq_alloc_disk(&xlo->tag_set, xlo);
+	if (IS_ERR(disk)) {
+		err = PTR_ERR(disk);
+		goto out_cleanup_tags;
+	}
+	xlo->xlo_queue = xlo->xlo_disk->queue;
+
+	blk_queue_max_hw_sectors(xlo->xlo_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, xlo->xlo_queue);
+
+	err = -ENOMEM;
+	xlo->xlo_fmt = xloop_file_fmt_alloc();
+	if (!xlo->xlo_fmt)
+		goto out_cleanup_disk;
+
+	xloop_file_fmt_set_xlo(xlo->xlo_fmt, xlo);
+
+	/*
+	 * 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 xloop device numbers will continue
+	 * to match the xloop minors, regardless of the number of partitions
+	 * used.
+	 *
+	 * If max_part is given, partition scanning is globally enabled for
+	 * all xloop devices. The minors for the main xloop devices will be
+	 * multiples of max_part.
+	 *
+	 * Note: Global-for-all-devices, set-only-at-init, read-only module
+	 * parameteters like 'max_xloop' 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(&xlo->xlo_refcnt, 0);
+	mutex_init(&xlo->xlo_mutex);
+	xlo->xlo_number = i;
+	spin_lock_init(&xlo->xlo_lock);
+	spin_lock_init(&xlo->xlo_work_lock);
+	disk->major = XLOOP_MAJOR;
+	disk->first_minor = i << part_shift;
+	disk->minors = 1 << part_shift;
+	disk->fops = &xlo_fops;
+	disk->private_data = xlo;
+	disk->queue = xlo->xlo_queue;
+	disk->events = DISK_EVENT_MEDIA_CHANGE;
+	disk->event_flags = DISK_EVENT_FLAG_UEVENT;
+	sprintf(disk->disk_name, "xloop%d", i);
+	/* Make this xloop device reachable from pathname. */
+	add_disk(disk);
+	/* Show this xloop device. */
+	mutex_lock(&xloop_ctl_mutex);
+	xlo->idr_visible = true;
+	mutex_unlock(&xloop_ctl_mutex);
+
+	/*
+	 * initialize debugfs entries
+	 *
+	 * create for each xloop device a debugfs directory under 'xloop' if
+	 * the 'block' directory exists, otherwise create the loop directory in
+	 * the root directory
+	 */
+#ifdef CONFIG_DEBUG_FS
+	xlo->xlo_dbgfs_dir = debugfs_create_dir(disk->disk_name, xloop_dbgfs_dir);
+
+	if (IS_ERR_OR_NULL(xlo->xlo_dbgfs_dir)) {
+		err = -ENODEV;
+		xlo->xlo_dbgfs_dir = NULL;
+		goto out_free_file_fmt;
+	}
+#endif
+
+	return i;
+
+out_free_file_fmt:
+	xloop_file_fmt_free(xlo->xlo_fmt);
+out_cleanup_disk:
+	blk_cleanup_disk(xlo->xlo_disk);
+out_cleanup_tags:
+	blk_mq_free_tag_set(&xlo->tag_set);
+out_free_idr:
+	mutex_lock(&xloop_ctl_mutex);
+	idr_remove(&xloop_index_idr, i);
+	mutex_unlock(&xloop_ctl_mutex);
+out_free_dev:
+	kfree(xlo);
+out:
+	return err;
+}
+
+static void xloop_remove(struct xloop_device *xlo)
+{
+	xloop_file_fmt_free(xlo->xlo_fmt);
+	debugfs_remove(xlo->xlo_dbgfs_dir);
+	/* Make this xloop device unreachable from pathname. */
+	del_gendisk(xlo->xlo_disk);
+	blk_cleanup_disk(xlo->xlo_disk);
+	blk_mq_free_tag_set(&xlo->tag_set);
+	mutex_lock(&xloop_ctl_mutex);
+	idr_remove(&xloop_index_idr, xlo->xlo_number);
+	mutex_unlock(&xloop_ctl_mutex);
+	/* There is no route which can find this xloop device. */
+	mutex_destroy(&xlo->xlo_mutex);
+	kfree(xlo);
+}
+
+static void xloop_probe(dev_t dev)
+{
+	int idx = MINOR(dev) >> part_shift;
+
+	if (max_xloop && idx >= max_xloop)
+		return;
+	xloop_add(idx);
+}
+
+static int xloop_control_remove(int idx)
+{
+	struct xloop_device *xlo;
+	int ret;
+
+	if (idx < 0) {
+		pr_warn("deleting an unspecified xloop device is not supported.\n");
+		return -EINVAL;
+	}
+
+	/* Hide this xloop device for serialization. */
+	ret = mutex_lock_killable(&xloop_ctl_mutex);
+	if (ret)
+		return ret;
+	xlo = idr_find(&xloop_index_idr, idx);
+	if (!xlo || !xlo->idr_visible)
+		ret = -ENODEV;
+	else
+		xlo->idr_visible = false;
+	mutex_unlock(&xloop_ctl_mutex);
+	if (ret)
+		return ret;
+
+	/* Check whether this xloop device can be removed. */
+	ret = mutex_lock_killable(&xlo->xlo_mutex);
+	if (ret)
+		goto mark_visible;
+	if (xlo->xlo_state != Xlo_unbound ||
+	    atomic_read(&xlo->xlo_refcnt) > 0) {
+		mutex_unlock(&xlo->xlo_mutex);
+		ret = -EBUSY;
+		goto mark_visible;
+	}
+	/* Mark this xloop device no longer open()-able. */
+	xlo->xlo_state = Xlo_deleting;
+	mutex_unlock(&xlo->xlo_mutex);
+
+	xloop_remove(xlo);
+	return 0;
+
+mark_visible:
+	/* Show this xloop device again. */
+	mutex_lock(&xloop_ctl_mutex);
+	xlo->idr_visible = true;
+	mutex_unlock(&xloop_ctl_mutex);
+	return ret;
+}
+
+static int xloop_control_get_free(int idx)
+{
+	struct xloop_device *xlo;
+	int id, ret;
+
+	ret = mutex_lock_killable(&xloop_ctl_mutex);
+	if (ret)
+		return ret;
+	idr_for_each_entry(&xloop_index_idr, xlo, id) {
+		/* Hitting a race results in creating a new xloop device which is harmless. */
+		if (xlo->idr_visible && data_race(xlo->xlo_state) == Xlo_unbound)
+			goto found;
+	}
+	mutex_unlock(&xloop_ctl_mutex);
+	return xloop_add(-1);
+found:
+	mutex_unlock(&xloop_ctl_mutex);
+	return id;
+}
+
+static long xloop_control_ioctl(struct file *file, unsigned int cmd,
+			       unsigned long parm)
+{
+	switch (cmd) {
+	case XLOOP_CTL_ADD:
+		return xloop_add(parm);
+	case XLOOP_CTL_REMOVE:
+		return xloop_control_remove(parm);
+	case XLOOP_CTL_GET_FREE:
+		return xloop_control_get_free(parm);
+	default:
+		return -ENOSYS;
+	}
+}
+
+static const struct file_operations xloop_ctl_fops = {
+	.open		= nonseekable_open,
+	.unlocked_ioctl	= xloop_control_ioctl,
+	.compat_ioctl	= xloop_control_ioctl,
+	.owner		= THIS_MODULE,
+	.llseek		= noop_llseek,
+};
+
+static struct miscdevice xloop_misc = {
+	.minor		= XLOOP_CTRL_MINOR,
+	.name		= "xloop-control",
+	.fops		= &xloop_ctl_fops,
+};
+
+MODULE_ALIAS_MISCDEV(XLOOP_CTRL_MINOR);
+MODULE_ALIAS("devname:xloop-control");
+
+static int __init xloop_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_xloop > 1UL << (MINORBITS - part_shift)) {
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	/*
+	 * If max_xloop is specified, create that many devices upfront.
+	 * This also becomes a hard limit. If max_xloop is not specified,
+	 * create CONFIG_BLK_DEV_XLOOP_MIN_COUNT xloop devices at module
+	 * init time. Loop devices can be requested on-demand with the
+	 * /dev/xloop-control interface, or be instantiated by accessing
+	 * a 'dead' device node.
+	 */
+	if (max_xloop)
+		nr = max_xloop;
+	else
+		nr = CONFIG_BLK_DEV_XLOOP_MIN_COUNT;
+
+	err = misc_register(&xloop_misc);
+	if (err < 0)
+		goto err_out;
+
+
+	if (__register_blkdev(XLOOP_MAJOR, "xloop", xloop_probe)) {
+		err = -EIO;
+		goto misc_out;
+	}
+
+#ifdef CONFIG_DEBUG_FS
+	xloop_dbgfs_dir = debugfs_create_dir("xloop", NULL);
+	if (IS_ERR_OR_NULL(xloop_dbgfs_dir)) {
+		err = -ENODEV;
+		goto blkdev_out;
+	}
+#endif
+
+	/* pre-create number of devices given by config or max_xloop */
+	for (i = 0; i < nr; i++)
+		xloop_add(i);
+
+	pr_info("module in version %s loaded\n", XLOOP_VERSION);
+	return 0;
+
+#ifdef CONFIG_DEBUG_FS
+blkdev_out:
+	unregister_blkdev(XLOOP_MAJOR, "xloop");
+#endif
+misc_out:
+	misc_deregister(&xloop_misc);
+err_out:
+	return err;
+}
+
+static void __exit xloop_exit(void)
+{
+	struct xloop_device *xlo;
+	int id;
+
+	unregister_blkdev(XLOOP_MAJOR, "xloop");
+	misc_deregister(&xloop_misc);
+
+	/*
+	 * There is no need to use xloop_ctl_mutex here, for nobody else can
+	 * access xloop_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(&xloop_index_idr, xlo, id)
+		xloop_remove(xlo);
+
+	idr_destroy(&xloop_index_idr);
+
+#ifdef CONFIG_DEBUG_FS
+	debugfs_remove(xloop_dbgfs_dir);
+#endif
+
+	pr_info("exit module\n");
+}
+
+module_init(xloop_init);
+module_exit(xloop_exit);
+
+#ifndef MODULE
+static int __init max_xloop_setup(char *str)
+{
+	max_xloop = simple_strtol(str, NULL, 0);
+	return 1;
+}
+
+__setup("max_xloop=", max_xloop_setup);
+#endif
diff --git a/src/kernel/xloop_main_5.15.h b/src/kernel/xloop_main_5.15.h
new file mode 100644
index 0000000..4126460
--- /dev/null
+++ b/src/kernel/xloop_main_5.15.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_main.h
+ *
+ * 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.
+ */
+#ifndef _LINUX_XLOOP_H
+#define _LINUX_XLOOP_H
+
+#include <linux/bio.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/spinlock.h>
+#include <linux/mutex.h>
+#include "uapi_xloop.h"
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
+
+#include "xloop_file_fmt.h"
+
+/* Possible states of device */
+enum {
+	Xlo_unbound,
+	Xlo_bound,
+	Xlo_rundown,
+	Xlo_deleting,
+};
+
+struct xloop_func_table;
+
+struct xloop_device {
+	int                     xlo_number;
+	atomic_t                xlo_refcnt;
+	loff_t                  xlo_offset;
+	loff_t                  xlo_sizelimit;
+	int                     xlo_flags;
+	int                     (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned raw_off, struct page *xloop_page, unsigned xloop_off, int size, sector_t real_block);
+	char                    xlo_file_name[XLO_NAME_SIZE];
+	char                    xlo_crypt_name[XLO_NAME_SIZE];
+	char                    xlo_encrypt_key[XLO_KEY_SIZE];
+	int                     xlo_encrypt_key_size;
+	struct xloop_func_table *xlo_encryption;
+	__u32                   xlo_init[2];
+	kuid_t                  xlo_key_owner;	/* Who set the key */
+	int                     (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
+
+	struct xloop_file_fmt   *xlo_fmt;
+
+	struct file             *xlo_backing_file;
+	struct block_device     *xlo_device;
+	void                    *key_data;
+
+	gfp_t                   old_gfp_mask;
+
+	spinlock_t              xlo_lock;
+	int                     xlo_state;
+	spinlock_t              xlo_work_lock;
+	struct workqueue_struct *workqueue;
+	struct work_struct      rootcg_work;
+	struct list_head        rootcg_cmd_list;
+	struct list_head        idle_worker_list;
+	struct rb_root          worker_tree;
+	struct timer_list       timer;
+	bool                    use_dio;
+	bool                    sysfs_inited;
+
+	struct request_queue    *xlo_queue;
+	struct blk_mq_tag_set   tag_set;
+	struct gendisk          *xlo_disk;
+	struct mutex            xlo_mutex;
+	bool                    idr_visible;
+
+#ifdef CONFIG_DEBUG_FS
+	struct dentry           *xlo_dbgfs_dir;
+#endif
+};
+
+struct xloop_cmd {
+	struct list_head           list_entry;
+	bool                       use_aio;  /* use AIO interface to handle I/O */
+	atomic_t                   ref;  /* only for aio */
+	long                       ret;
+	struct kiocb               iocb;
+	struct bio_vec             *bvec;
+	struct cgroup_subsys_state *blkcg_css;
+	struct cgroup_subsys_state *memcg_css;
+};
+
+/* Support for loadable transfer modules */
+struct xloop_func_table {
+	int           number;  /* filter type */
+	int           (*transfer)(struct xloop_device *xlo, int cmd, struct page *raw_page, unsigned raw_off, struct page *xloop_page, unsigned xloop_off, int size, sector_t real_block);
+	int           (*init)(struct xloop_device *xlo, const struct xloop_info64 *info);
+	/* release is called from xloop_unregister_transfer or clr_fd */
+	int           (*release)(struct xloop_device *xlo);
+	int           (*ioctl)(struct xloop_device *xlo, int cmd, unsigned long arg);
+	struct module *owner;
+};
+
+extern inline struct device *xloop_device_to_dev(struct xloop_device *xlo);
+
+int xloop_register_transfer(struct xloop_func_table *funcs);
+int xloop_unregister_transfer(int number);
+
+#endif