Add support for RHEL 8.5

6 files changed, 2231 insertions, 14 deletions

diff --git a/src/kernel/xloop_main.c b/src/kernel/xloop_main.c
index b3f7963..cd1a767 100644
--- a/src/kernel/xloop_main.c
+++ b/src/kernel/xloop_main.c
@@ -1,6 +1,10 @@
-#include <linux/version.h>
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+#include "xloop_main.h"
+
+#if RHEL_CHECK_VERSION(RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(8, 5))
+#include "xloop_main_rhel_8.5.c"
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
 #include "xloop_main_4.18.c"
 #else
 #include "xloop_main_5.15.c"
diff --git a/src/kernel/xloop_main.h b/src/kernel/xloop_main.h
index c1cc919..3649039 100644
--- a/src/kernel/xloop_main.h
+++ b/src/kernel/xloop_main.h
@@ -1,6 +1,15 @@
 #include <linux/version.h>
 
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
+/* 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
+
+#if RHEL_CHECK_VERSION(RHEL_RELEASE_CODE >= RHEL_RELEASE_VERSION(8, 5))
+#include "xloop_main_rhel_8.5.h"
+#elif LINUX_VERSION_CODE < KERNEL_VERSION(5, 15, 0)
 #include "xloop_main_4.18.h"
 #else
 #include "xloop_main_5.15.h"
diff --git a/src/kernel/xloop_main_4.18.c b/src/kernel/xloop_main_4.18.c
index 9fe0c70..dde0ad0 100644
--- a/src/kernel/xloop_main_4.18.c
+++ b/src/kernel/xloop_main_4.18.c
@@ -53,8 +53,6 @@
  *
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/sched.h>
@@ -96,13 +94,6 @@
 
 #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);
 
diff --git a/src/kernel/xloop_main_5.15.c b/src/kernel/xloop_main_5.15.c
index d133709..9866c2b 100644
--- a/src/kernel/xloop_main_5.15.c
+++ b/src/kernel/xloop_main_5.15.c
@@ -53,8 +53,6 @@
  *
  */
 
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
 #include <linux/module.h>
 #include <linux/moduleparam.h>
 #include <linux/sched.h>
diff --git a/src/kernel/xloop_main_rhel_8.5.c b/src/kernel/xloop_main_rhel_8.5.c
new file mode 100644
index 0000000..eb1538e
--- /dev/null
+++ b/src/kernel/xloop_main_rhel_8.5.c
@@ -0,0 +1,2111 @@
+// 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
+ *
+ */
+
+#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>
+
+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;
+
+	bd_set_nr_sectors(bdev, size);
+
+	if (!set_capacity_revalidate_and_notify(xlo->xlo_disk, size, false))
+		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+}
+
+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;
+
+	mutex_lock(&bdev->bd_mutex);
+	rc = bdev_disk_changed(bdev, false);
+	mutex_unlock(&bdev->bd_mutex);
+	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)
+{
+	current->flags |= PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO;
+	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;
+	struct block_device *claimed_bdev = NULL;
+	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)) {
+		claimed_bdev = bdev->bd_contains;
+		error = bd_prepare_to_claim(bdev, claimed_bdev, xloop_configure);
+		if (error)
+			goto out_putf;
+	}
+
+	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 (claimed_bdev)
+		bd_abort_claiming(bdev, claimed_bdev, xloop_configure);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&xloop_ctl_mutex);
+out_bdev:
+	if (claimed_bdev)
+		bd_abort_claiming(bdev, claimed_bdev, xloop_configure);
+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) {
+		bd_set_nr_sectors(bdev, 0);
+		/* let user-space know about this change */
+		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
+	}
+	mapping_set_gfp_mask(filp->f_mapping, gfp);
+	/* 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 (!release)
+			mutex_lock(&bdev->bd_mutex);
+		err = bdev_disk_changed(bdev, false);
+		if (!release)
+			mutex_unlock(&bdev->bd_mutex);
+		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;
+		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];
+	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);
+		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;
+	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 (likely(!blk_should_fake_timeout(rq->q)))
+			blk_mq_complete_request(rq);
+	}
+}
+
+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);
+	xlo->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_STACKING;
+	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 void xloop_probe(dev_t dev)
+{
+	struct xloop_device *xlo;
+	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);
+	mutex_unlock(&xloop_ctl_mutex);
+}
+
+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
+
+	if (__register_blkdev(XLOOP_MAJOR, "xloop", xloop_probe)) {
+		err = -EIO;
+		goto misc_out;
+	}
+
+	/* 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 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_rhel_8.5.h b/src/kernel/xloop_main_rhel_8.5.h
new file mode 100644
index 0000000..97c2654
--- /dev/null
+++ b/src/kernel/xloop_main_rhel_8.5.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