diff --git a/drivers/block/loop/Kconfig b/drivers/block/loop/Kconfig
index 355f1554b848..a3fa6768c7d7 100644
--- a/drivers/block/loop/Kconfig
+++ b/drivers/block/loop/Kconfig
@@ -82,3 +82,12 @@ config BLK_DEV_LOOP_FILE_FMT_RAW
 	---help---
 	  Say Y or M here if you want to enable the binary (RAW) file format
 	  support of the loop device module.
+
+config BLK_DEV_LOOP_FILE_FMT_QCOW
+	tristate "Loop device QCOW file format support"
+	  select ZLIB_INFLATE
+	  select ZLIB_DEFLATE
+	  depends on BLK_DEV_LOOP
+	  ---help---
+	    Say Y or M here if you want to enable the QEMU's copy on write (QCOW)
+	    file format support of the loop device module.
diff --git a/drivers/block/loop/Makefile b/drivers/block/loop/Makefile
index 2cd69e878453..f2fe116c2954 100644
--- a/drivers/block/loop/Makefile
+++ b/drivers/block/loop/Makefile
@@ -6,3 +6,8 @@ obj-$(CONFIG_BLK_DEV_LOOP)               += loop.o
 obj-$(CONFIG_BLK_DEV_CRYPTOLOOP)         += cryptoloop.o
 
 obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_RAW)  += loop_file_fmt_raw.o
+
+loop_file_fmt_qcow-y                     += loop_file_fmt_qcow_main.o \
+                                            loop_file_fmt_qcow_cluster.o \
+                                            loop_file_fmt_qcow_cache.o
+obj-$(CONFIG_BLK_DEV_LOOP_FILE_FMT_QCOW) += loop_file_fmt_qcow.o
diff --git a/drivers/block/loop/loop_file_fmt_qcow_cache.c b/drivers/block/loop/loop_file_fmt_qcow_cache.c
new file mode 100644
index 000000000000..7d3af7398f04
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_cache.c
@@ -0,0 +1,218 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow_cache.c
+ *
+ * QCOW file format driver for the loop device module.
+ *
+ * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
+ * L2/refcount table cache for the QCOW2 format.
+ *
+ * The copyright (C) 2010 of the original code is owned by
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/log2.h>
+#include <linux/types.h>
+#include <linux/limits.h>
+#include <linux/fs.h>
+#include <linux/vmalloc.h>
+
+#include "loop_file_fmt_qcow_main.h"
+#include "loop_file_fmt_qcow_cache.h"
+
+static inline void *__loop_file_fmt_qcow_cache_get_table_addr(
+	struct loop_file_fmt_qcow_cache *c, int table)
+{
+	return (u8 *) c->table_array + (size_t) table * c->table_size;
+}
+
+static inline int __loop_file_fmt_qcow_cache_get_table_idx(
+	struct loop_file_fmt_qcow_cache *c, void *table)
+{
+	ptrdiff_t table_offset = (u8 *) table - (u8 *) c->table_array;
+	int idx = table_offset / c->table_size;
+	ASSERT(idx >= 0 && idx < c->size && table_offset % c->table_size == 0);
+	return idx;
+}
+
+static inline const char *__loop_file_fmt_qcow_cache_get_name(
+	struct loop_file_fmt *lo_fmt, struct loop_file_fmt_qcow_cache *c)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+	if (c == qcow_data->refcount_block_cache) {
+		return "refcount block";
+	} else if (c == qcow_data->l2_table_cache) {
+		return "L2 table";
+	} else {
+		/* do not abort, because this is not critical */
+		return "unknown";
+	}
+}
+
+struct loop_file_fmt_qcow_cache *loop_file_fmt_qcow_cache_create(
+	struct loop_file_fmt *lo_fmt, int num_tables, unsigned table_size)
+{
+#ifdef CONFIG_DEBUG_DRIVER
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+#endif
+	struct loop_file_fmt_qcow_cache *c;
+
+	ASSERT(num_tables > 0);
+	ASSERT(is_power_of_2(table_size));
+	ASSERT(table_size >= (1 << QCOW_MIN_CLUSTER_BITS));
+	ASSERT(table_size <= qcow_data->cluster_size);
+
+	c = kzalloc(sizeof(*c), GFP_KERNEL);
+	if (!c) {
+		return NULL;
+	}
+
+	c->size = num_tables;
+	c->table_size = table_size;
+	c->entries = vzalloc(sizeof(struct loop_file_fmt_qcow_cache_table) *
+		num_tables);
+	c->table_array = vzalloc(num_tables * c->table_size);
+
+	if (!c->entries || !c->table_array) {
+		vfree(c->table_array);
+		vfree(c->entries);
+		kfree(c);
+		c = NULL;
+	}
+
+	return c;
+}
+
+void loop_file_fmt_qcow_cache_destroy(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_file_fmt_qcow_cache *c = qcow_data->l2_table_cache;
+	int i;
+
+	for (i = 0; i < c->size; i++) {
+		ASSERT(c->entries[i].ref == 0);
+	}
+
+	vfree(c->table_array);
+	vfree(c->entries);
+	kfree(c);
+}
+
+static int __loop_file_fmt_qcow_cache_entry_flush(
+	struct loop_file_fmt_qcow_cache *c, int i)
+{
+	if (!c->entries[i].dirty || !c->entries[i].offset) {
+		return 0;
+	} else {
+		printk(KERN_ERR "loop_file_fmt_qcow: Flush dirty cache tables "
+			"is not supported yet\n");
+		return -ENOSYS;
+	}
+}
+
+static int __loop_file_fmt_qcow_cache_do_get(struct loop_file_fmt *lo_fmt,
+	struct loop_file_fmt_qcow_cache *c, u64 offset, void **table,
+	bool read_from_disk)
+{
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	int i;
+	int ret;
+	int lookup_index;
+	u64 min_lru_counter = U64_MAX;
+	int min_lru_index = -1;
+	u64 read_offset;
+	size_t len;
+
+	ASSERT(offset != 0);
+
+	if (!IS_ALIGNED(offset, c->table_size)) {
+		printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: Cannot get "
+			"entry from %s cache: offset %llx is unaligned\n",
+			__loop_file_fmt_qcow_cache_get_name(lo_fmt, c),
+			offset);
+		return -EIO;
+	}
+
+	/* Check if the table is already cached */
+	i = lookup_index = (offset / c->table_size * 4) % c->size;
+	do {
+		const struct loop_file_fmt_qcow_cache_table *t =
+			&c->entries[i];
+		if (t->offset == offset) {
+			goto found;
+		}
+		if (t->ref == 0 && t->lru_counter < min_lru_counter) {
+			min_lru_counter = t->lru_counter;
+			min_lru_index = i;
+		}
+		if (++i == c->size) {
+			i = 0;
+		}
+	} while (i != lookup_index);
+
+	if (min_lru_index == -1) {
+		BUG();
+		panic("Oops: This can't happen in current synchronous code, "
+			"but leave the check here as a reminder for whoever "
+			"starts using AIO with the QCOW cache");
+	}
+
+	/* Cache miss: write a table back and replace it */
+	i = min_lru_index;
+
+	ret = __loop_file_fmt_qcow_cache_entry_flush(c, i);
+	if (ret < 0) {
+		return ret;
+	}
+
+	c->entries[i].offset = 0;
+	if (read_from_disk) {
+		read_offset = offset;
+		len = kernel_read(lo->lo_backing_file,
+			__loop_file_fmt_qcow_cache_get_table_addr(c, i),
+			c->table_size, &read_offset);
+		if (len < 0) {
+			len = ret;
+			return ret;
+		}
+	}
+
+	c->entries[i].offset = offset;
+
+	/* And return the right table */
+found:
+	c->entries[i].ref++;
+	*table = __loop_file_fmt_qcow_cache_get_table_addr(c, i);
+
+	return 0;
+}
+
+int loop_file_fmt_qcow_cache_get(struct loop_file_fmt *lo_fmt, u64 offset,
+	void **table)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_file_fmt_qcow_cache *c = qcow_data->l2_table_cache;
+
+	return __loop_file_fmt_qcow_cache_do_get(lo_fmt, c, offset, table,
+		true);
+}
+
+void loop_file_fmt_qcow_cache_put(struct loop_file_fmt *lo_fmt, void **table)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_file_fmt_qcow_cache *c = qcow_data->l2_table_cache;
+	int i = __loop_file_fmt_qcow_cache_get_table_idx(c, *table);
+
+	c->entries[i].ref--;
+	*table = NULL;
+
+	if (c->entries[i].ref == 0) {
+		c->entries[i].lru_counter = ++c->lru_counter;
+	}
+
+	ASSERT(c->entries[i].ref >= 0);
+}
diff --git a/drivers/block/loop/loop_file_fmt_qcow_cache.h b/drivers/block/loop/loop_file_fmt_qcow_cache.h
new file mode 100644
index 000000000000..1abf9b2b7c09
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_cache.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow_cache.h
+ *
+ * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
+ * L2/refcount table cache for the QCOW2 format.
+ *
+ * The copyright (C) 2010 of the original code is owned by
+ * Kevin Wolf <kwolf@redhat.com>
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#ifndef _LINUX_LOOP_FILE_FMT_QCOW_CACHE_H
+#define _LINUX_LOOP_FILE_FMT_QCOW_CACHE_H
+
+#include "loop_file_fmt.h"
+
+struct loop_file_fmt_qcow_cache_table {
+	s64 offset;
+	u64 lru_counter;
+	int ref;
+	bool dirty;
+};
+
+struct loop_file_fmt_qcow_cache {
+	struct loop_file_fmt_qcow_cache_table *entries;
+	struct loop_file_fmt_qcow_cache *depends;
+	int size;
+	int table_size;
+	bool depends_on_flush;
+	void *table_array;
+	u64 lru_counter;
+	u64 cache_clean_lru_counter;
+};
+
+extern struct loop_file_fmt_qcow_cache *loop_file_fmt_qcow_cache_create(
+	struct loop_file_fmt *lo_fmt,
+	int num_tables,
+	unsigned table_size);
+
+extern void loop_file_fmt_qcow_cache_destroy(struct loop_file_fmt *lo_fmt);
+
+extern int loop_file_fmt_qcow_cache_get(struct loop_file_fmt *lo_fmt,
+					u64 offset,
+					void **table);
+
+extern void loop_file_fmt_qcow_cache_put(struct loop_file_fmt *lo_fmt,
+					 void **table);
+
+#endif
diff --git a/drivers/block/loop/loop_file_fmt_qcow_cluster.c b/drivers/block/loop/loop_file_fmt_qcow_cluster.c
new file mode 100644
index 000000000000..9c91a8b4aeb7
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_cluster.c
@@ -0,0 +1,270 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow_cluster.c
+ *
+ * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
+ * Cluster calculation and lookup for the QCOW2 format.
+ *
+ * The copyright (C) 2004-2006 of the original code is owned by Fabrice Bellard.
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+
+#include "loop_file_fmt.h"
+#include "loop_file_fmt_qcow_main.h"
+#include "loop_file_fmt_qcow_cache.h"
+#include "loop_file_fmt_qcow_cluster.h"
+
+/*
+ * Loads a L2 slice into memory (L2 slices are the parts of L2 tables
+ * that are loaded by the qcow2 cache). If the slice is in the cache,
+ * the cache is used; otherwise the L2 slice is loaded from the image
+ * file.
+ */
+static int __loop_file_fmt_qcow_cluster_l2_load(struct loop_file_fmt *lo_fmt,
+	u64 offset, u64 l2_offset, u64 **l2_slice)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+	int start_of_slice = sizeof(u64) * (
+		loop_file_fmt_qcow_offset_to_l2_index(qcow_data, offset) -
+		loop_file_fmt_qcow_offset_to_l2_slice_index(qcow_data, offset)
+	);
+
+	ASSERT(qcow_data->l2_table_cache != NULL);
+	return loop_file_fmt_qcow_cache_get(lo_fmt, l2_offset + start_of_slice,
+		(void **) l2_slice);
+}
+
+/*
+ * Checks how many clusters in a given L2 slice are contiguous in the image
+ * file. As soon as one of the flags in the bitmask stop_flags changes compared
+ * to the first cluster, the search is stopped and the cluster is not counted
+ * as contiguous. (This allows it, for example, to stop at the first compressed
+ * cluster which may require a different handling)
+ */
+static int __loop_file_fmt_qcow_cluster_count_contiguous(
+	struct loop_file_fmt *lo_fmt, int nb_clusters, int cluster_size,
+	u64 *l2_slice, u64 stop_flags)
+{
+	int i;
+	enum loop_file_fmt_qcow_cluster_type first_cluster_type;
+	u64 mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
+	u64 first_entry = be64_to_cpu(l2_slice[0]);
+	u64 offset = first_entry & mask;
+
+	first_cluster_type = loop_file_fmt_qcow_get_cluster_type(lo_fmt,
+		first_entry);
+	if (first_cluster_type == QCOW_CLUSTER_UNALLOCATED) {
+		return 0;
+	}
+
+	/* must be allocated */
+	ASSERT(first_cluster_type == QCOW_CLUSTER_NORMAL ||
+		first_cluster_type == QCOW_CLUSTER_ZERO_ALLOC);
+
+	for (i = 0; i < nb_clusters; i++) {
+		u64 l2_entry = be64_to_cpu(l2_slice[i]) & mask;
+		if (offset + (u64) i * cluster_size != l2_entry) {
+			break;
+		}
+	}
+
+	return i;
+}
+
+/*
+ * Checks how many consecutive unallocated clusters in a given L2
+ * slice have the same cluster type.
+ */
+static int __loop_file_fmt_qcow_cluster_count_contiguous_unallocated(
+	struct loop_file_fmt *lo_fmt, int nb_clusters, u64 *l2_slice,
+	enum loop_file_fmt_qcow_cluster_type wanted_type)
+{
+	int i;
+
+	ASSERT(wanted_type == QCOW_CLUSTER_ZERO_PLAIN ||
+		wanted_type == QCOW_CLUSTER_UNALLOCATED);
+
+	for (i = 0; i < nb_clusters; i++) {
+		u64 entry = be64_to_cpu(l2_slice[i]);
+		enum loop_file_fmt_qcow_cluster_type type =
+			loop_file_fmt_qcow_get_cluster_type(lo_fmt, entry);
+
+		if (type != wanted_type) {
+			break;
+		}
+	}
+
+	return i;
+}
+
+/*
+ * For a given offset of the virtual disk, find the cluster type and offset in
+ * the qcow2 file. The offset is stored in *cluster_offset.
+ *
+ * On entry, *bytes is the maximum number of contiguous bytes starting at
+ * offset that we are interested in.
+ *
+ * On exit, *bytes is the number of bytes starting at offset that have the same
+ * cluster type and (if applicable) are stored contiguously in the image file.
+ * Compressed clusters are always returned one by one.
+ *
+ * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
+ * cases.
+ */
+int loop_file_fmt_qcow_cluster_get_offset(struct loop_file_fmt *lo_fmt,
+	u64 offset, unsigned int *bytes, u64 *cluster_offset)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	unsigned int l2_index;
+	u64 l1_index, l2_offset, *l2_slice;
+	int c;
+	unsigned int offset_in_cluster;
+	u64 bytes_available, bytes_needed, nb_clusters;
+	enum loop_file_fmt_qcow_cluster_type type;
+	int ret;
+
+	offset_in_cluster = loop_file_fmt_qcow_offset_into_cluster(qcow_data,
+		offset);
+	bytes_needed = (u64) *bytes + offset_in_cluster;
+
+	/* compute how many bytes there are between the start of the cluster
+	 * containing offset and the end of the l2 slice that contains
+	 * the entry pointing to it */
+	bytes_available = ((u64)(
+		qcow_data->l2_slice_size -
+		loop_file_fmt_qcow_offset_to_l2_slice_index(qcow_data, offset))
+	) << qcow_data->cluster_bits;
+
+	if (bytes_needed > bytes_available) {
+		bytes_needed = bytes_available;
+	}
+
+	*cluster_offset = 0;
+
+	/* seek to the l2 offset in the l1 table */
+	l1_index = loop_file_fmt_qcow_offset_to_l1_index(qcow_data, offset);
+	if (l1_index >= qcow_data->l1_size) {
+		type = QCOW_CLUSTER_UNALLOCATED;
+		goto out;
+	}
+
+	l2_offset = qcow_data->l1_table[l1_index] & L1E_OFFSET_MASK;
+	if (!l2_offset) {
+		type = QCOW_CLUSTER_UNALLOCATED;
+		goto out;
+	}
+
+	if (loop_file_fmt_qcow_offset_into_cluster(qcow_data, l2_offset)) {
+		printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: L2 table "
+			"offset %llx unaligned (L1 index: %llx)", l2_offset,
+			l1_index);
+		return -EIO;
+	}
+
+	/* load the l2 slice in memory */
+	ret = __loop_file_fmt_qcow_cluster_l2_load(lo_fmt, offset, l2_offset,
+		&l2_slice);
+	if (ret < 0) {
+		return ret;
+	}
+
+	/* find the cluster offset for the given disk offset */
+	l2_index = loop_file_fmt_qcow_offset_to_l2_slice_index(qcow_data,
+		offset);
+	*cluster_offset = be64_to_cpu(l2_slice[l2_index]);
+
+	nb_clusters = loop_file_fmt_qcow_size_to_clusters(qcow_data,
+		bytes_needed);
+	/* bytes_needed <= *bytes + offset_in_cluster, both of which are
+	 * unsigned integers; the minimum cluster size is 512, so this
+	 * assertion is always true */
+	ASSERT(nb_clusters <= INT_MAX);
+
+	type = loop_file_fmt_qcow_get_cluster_type(lo_fmt, *cluster_offset);
+	if (qcow_data->qcow_version < 3 && (
+			type == QCOW_CLUSTER_ZERO_PLAIN ||
+			type == QCOW_CLUSTER_ZERO_ALLOC)) {
+		printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: zero cluster "
+			"entry found in pre-v3 image (L2 offset: %llx, "
+			"L2 index: %x)\n", l2_offset, l2_index);
+		ret = -EIO;
+		goto fail;
+	}
+	switch (type) {
+	case QCOW_CLUSTER_COMPRESSED:
+		if (loop_file_fmt_qcow_has_data_file(lo_fmt)) {
+			printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: "
+				"compressed cluster entry found in image with "
+				"external data file (L2 offset: %llx, "
+				"L2 index: %x)", l2_offset, l2_index);
+			ret = -EIO;
+			goto fail;
+		}
+		/* Compressed clusters can only be processed one by one */
+		c = 1;
+		*cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
+		break;
+	case QCOW_CLUSTER_ZERO_PLAIN:
+	case QCOW_CLUSTER_UNALLOCATED:
+		/* how many empty clusters ? */
+		c = __loop_file_fmt_qcow_cluster_count_contiguous_unallocated(
+			lo_fmt, nb_clusters, &l2_slice[l2_index], type);
+		*cluster_offset = 0;
+		break;
+	case QCOW_CLUSTER_ZERO_ALLOC:
+	case QCOW_CLUSTER_NORMAL:
+		/* how many allocated clusters ? */
+		c = __loop_file_fmt_qcow_cluster_count_contiguous(lo_fmt,
+			nb_clusters, qcow_data->cluster_size,
+			&l2_slice[l2_index], QCOW_OFLAG_ZERO);
+		*cluster_offset &= L2E_OFFSET_MASK;
+		if (loop_file_fmt_qcow_offset_into_cluster(qcow_data,
+				*cluster_offset)) {
+			printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: "
+				"cluster allocation offset %llx unaligned "
+				"(L2 offset: %llx, L2 index: %x)\n",
+				*cluster_offset, l2_offset, l2_index);
+			ret = -EIO;
+			goto fail;
+		}
+		if (loop_file_fmt_qcow_has_data_file(lo_fmt) &&
+			*cluster_offset != offset - offset_in_cluster) {
+			printk_ratelimited(KERN_ERR "loop_file_fmt_qcow: "
+				"external data file host cluster offset %llx "
+				"does not match guest cluster offset: %llx, "
+				"L2 index: %x)", *cluster_offset,
+				offset - offset_in_cluster, l2_index);
+			ret = -EIO;
+			goto fail;
+		}
+		break;
+	default:
+		BUG();
+	}
+
+	loop_file_fmt_qcow_cache_put(lo_fmt, (void **) &l2_slice);
+
+	bytes_available = (s64) c * qcow_data->cluster_size;
+
+out:
+	if (bytes_available > bytes_needed) {
+		bytes_available = bytes_needed;
+	}
+
+	/* bytes_available <= bytes_needed <= *bytes + offset_in_cluster;
+	 * subtracting offset_in_cluster will therefore definitely yield
+	 * something not exceeding UINT_MAX */
+	ASSERT(bytes_available - offset_in_cluster <= UINT_MAX);
+	*bytes = bytes_available - offset_in_cluster;
+
+	return type;
+
+fail:
+	loop_file_fmt_qcow_cache_put(lo_fmt, (void **) &l2_slice);
+	return ret;
+}
diff --git a/drivers/block/loop/loop_file_fmt_qcow_cluster.h b/drivers/block/loop/loop_file_fmt_qcow_cluster.h
new file mode 100644
index 000000000000..d62e3318f6ce
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_cluster.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow_cluster.h
+ *
+ * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
+ * Cluster calculation and lookup for the QCOW2 format.
+ *
+ * The copyright (C) 2004-2006 of the original code is owned by Fabrice Bellard.
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#ifndef _LINUX_LOOP_FILE_FMT_QCOW_CLUSTER_H
+#define _LINUX_LOOP_FILE_FMT_QCOW_CLUSTER_H
+
+#include "loop_file_fmt.h"
+
+extern int loop_file_fmt_qcow_cluster_get_offset(struct loop_file_fmt *lo_fmt,
+						 u64 offset,
+						 unsigned int *bytes,
+						 u64 *cluster_offset);
+
+#endif
diff --git a/drivers/block/loop/loop_file_fmt_qcow_main.c b/drivers/block/loop/loop_file_fmt_qcow_main.c
new file mode 100644
index 000000000000..4fb786b340f7
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_main.c
@@ -0,0 +1,945 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow.c
+ *
+ * QCOW file format driver for the loop device module.
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/types.h>
+#include <linux/limits.h>
+#include <linux/blkdev.h>
+#include <linux/bio.h>
+#include <linux/bvec.h>
+#include <linux/mutex.h>
+#include <linux/uio.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+#include <linux/zlib.h>
+
+#include "loop_file_fmt.h"
+#include "loop_file_fmt_qcow_main.h"
+#include "loop_file_fmt_qcow_cache.h"
+#include "loop_file_fmt_qcow_cluster.h"
+
+static int __qcow_file_fmt_header_read(struct loop_file_fmt *lo_fmt,
+	struct loop_file_fmt_qcow_header *header)
+{
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	ssize_t len;
+	loff_t offset;
+	int ret = 0;
+
+	/* read QCOW header */
+	offset = 0;
+	len = kernel_read(lo->lo_backing_file, header, sizeof(*header),
+		&offset);
+	if (len < 0) {
+		printk(KERN_ERR "loop_file_fmt_qcow: could not read QCOW "
+			"header");
+		return len;
+	}
+
+	header->magic = be32_to_cpu(header->magic);
+	header->version = be32_to_cpu(header->version);
+	header->backing_file_offset = be64_to_cpu(header->backing_file_offset);
+	header->backing_file_size = be32_to_cpu(header->backing_file_size);
+	header->cluster_bits = be32_to_cpu(header->cluster_bits);
+	header->size = be64_to_cpu(header->size);
+	header->crypt_method = be32_to_cpu(header->crypt_method);
+	header->l1_size = be32_to_cpu(header->l1_size);
+	header->l1_table_offset = be64_to_cpu(header->l1_table_offset);
+	header->refcount_table_offset =
+		be64_to_cpu(header->refcount_table_offset);
+	header->refcount_table_clusters =
+		be32_to_cpu(header->refcount_table_clusters);
+	header->nb_snapshots = be32_to_cpu(header->nb_snapshots);
+	header->snapshots_offset = be64_to_cpu(header->snapshots_offset);
+
+	/* check QCOW file format and header version */
+	if (header->magic != QCOW_MAGIC) {
+		printk(KERN_ERR "loop_file_fmt_qcow: image is not in QCOW "
+			"format");
+		return -EINVAL;
+	}
+
+	if (header->version < 2 || header->version > 3) {
+		printk(KERN_ERR "loop_file_fmt_qcow: unsupported QCOW version "
+			"%d", header->version);
+		return -ENOTSUPP;
+	}
+
+	/* initialize version 3 header fields */
+	if (header->version == 2) {
+		header->incompatible_features =  0;
+		header->compatible_features   =  0;
+		header->autoclear_features    =  0;
+		header->refcount_order        =  4;
+		header->header_length         = 72;
+	} else {
+		header->incompatible_features =
+			be64_to_cpu(header->incompatible_features);
+		header->compatible_features =
+			be64_to_cpu(header->compatible_features);
+		header->autoclear_features =
+			be64_to_cpu(header->autoclear_features);
+		header->refcount_order = be32_to_cpu(header->refcount_order);
+		header->header_length = be32_to_cpu(header->header_length);
+
+		if (header->header_length < 104) {
+			printk(KERN_ERR "loop_file_fmt_qcow: QCOW header too "
+				"short");
+			return -EINVAL;
+		}
+	}
+
+	return ret;
+}
+
+static int __qcow_file_fmt_validate_table(struct loop_file_fmt *lo_fmt,
+	u64 offset, u64 entries, size_t entry_len, s64 max_size_bytes,
+	const char *table_name)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+	if (entries > max_size_bytes / entry_len) {
+		printk(KERN_INFO "loop_file_fmt_qcow: %s too large",
+			table_name);
+		return -EFBIG;
+	}
+
+	/* Use signed S64_MAX as the maximum even for u64 header fields,
+	 * because values will be passed to qemu functions taking s64. */
+	if ((S64_MAX - entries * entry_len < offset) || (
+		loop_file_fmt_qcow_offset_into_cluster(qcow_data, offset) != 0)
+	) {
+		printk(KERN_INFO "loop_file_fmt_qcow: %s offset invalid",
+			table_name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static inline loff_t __qcow_file_fmt_rq_get_pos(struct loop_file_fmt *lo_fmt,
+						struct request *rq)
+{
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	return ((loff_t) blk_rq_pos(rq) << 9) + lo->lo_offset;
+}
+
+static int __qcow_file_fmt_compression_init(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	int ret = 0;
+
+	qcow_data->strm = kzalloc(sizeof(*qcow_data->strm), GFP_KERNEL);
+	if (!qcow_data->strm) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	qcow_data->strm->workspace = vzalloc(zlib_inflate_workspacesize());
+	if (!qcow_data->strm->workspace) {
+		ret = -ENOMEM;
+		goto out_free_strm;
+	}
+
+	return ret;
+
+out_free_strm:
+	kfree(qcow_data->strm);
+out:
+	return ret;
+}
+
+static void __qcow_file_fmt_compression_exit(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+	if (qcow_data->strm->workspace)
+		vfree(qcow_data->strm->workspace);
+
+	if (qcow_data->strm)
+		kfree(qcow_data->strm);
+}
+
+#ifdef CONFIG_DEBUG_FS
+static void __qcow_file_fmt_header_to_buf(struct loop_file_fmt *lo_fmt,
+	const struct loop_file_fmt_qcow_header *header)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	char *header_buf = qcow_data->dbgfs_file_qcow_header_buf;
+	ssize_t len = 0;
+
+	len += sprintf(header_buf + len, "magic: %d\n",
+		header->magic);
+	len += sprintf(header_buf + len, "version: %d\n",
+		header->version);
+	len += sprintf(header_buf + len, "backing_file_offset: %lld\n",
+		header->backing_file_offset);
+	len += sprintf(header_buf + len, "backing_file_size: %d\n",
+		header->backing_file_size);
+	len += sprintf(header_buf + len, "cluster_bits: %d\n",
+		header->cluster_bits);
+	len += sprintf(header_buf + len, "size: %lld\n",
+		header->size);
+	len += sprintf(header_buf + len, "crypt_method: %d\n",
+		header->crypt_method);
+	len += sprintf(header_buf + len, "l1_size: %d\n",
+		header->l1_size);
+	len += sprintf(header_buf + len, "l1_table_offset: %lld\n",
+		header->l1_table_offset);
+	len += sprintf(header_buf + len, "refcount_table_offset: %lld\n",
+		header->refcount_table_offset);
+	len += sprintf(header_buf + len, "refcount_table_clusters: %d\n",
+		header->refcount_table_clusters);
+	len += sprintf(header_buf + len, "nb_snapshots: %d\n",
+		header->nb_snapshots);
+	len += sprintf(header_buf + len, "snapshots_offset: %lld\n",
+		header->snapshots_offset);
+
+	if (header->version == 3) {
+		len += sprintf(header_buf + len,
+			"incompatible_features: %lld\n",
+			header->incompatible_features);
+		len += sprintf(header_buf + len,
+			"compatible_features: %lld\n",
+			header->compatible_features);
+		len += sprintf(header_buf + len,
+			"autoclear_features: %lld\n",
+			header->autoclear_features);
+		len += sprintf(header_buf + len,
+			"refcount_order: %d\n",
+			header->refcount_order);
+		len += sprintf(header_buf + len,
+			"header_length: %d\n",
+			header->header_length);
+	}
+
+	ASSERT(len < QCOW_HEADER_BUF_LEN);
+}
+
+static ssize_t __qcow_file_fmt_dbgfs_hdr_read(struct file *file,
+	char __user *buf, size_t size, loff_t *ppos)
+{
+	struct loop_file_fmt *lo_fmt = file->private_data;
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	char *header_buf = qcow_data->dbgfs_file_qcow_header_buf;
+
+	return simple_read_from_buffer(buf, size, ppos, header_buf,
+		strlen(header_buf));
+}
+
+static const struct file_operations qcow_file_fmt_dbgfs_hdr_fops = {
+	.open = simple_open,
+	.read = __qcow_file_fmt_dbgfs_hdr_read
+};
+
+static ssize_t __qcow_file_fmt_dbgfs_ofs_read(struct file *file,
+	char __user *buf, size_t size, loff_t *ppos)
+{
+	struct loop_file_fmt *lo_fmt = file->private_data;
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	unsigned int cur_bytes = 1;
+	u64 offset = 0;
+	u64 cluster_offset = 0;
+	s64 offset_in_cluster = 0;
+	ssize_t len = 0;
+	int ret = 0;
+
+	/* read the share debugfs offset */
+	ret = mutex_lock_interruptible(&qcow_data->dbgfs_qcow_offset_mutex);
+	if (ret)
+		return ret;
+
+	offset = qcow_data->dbgfs_qcow_offset;
+	mutex_unlock(&qcow_data->dbgfs_qcow_offset_mutex);
+
+	/* calculate and print the cluster offset */
+	ret = loop_file_fmt_qcow_cluster_get_offset(lo_fmt,
+		offset, &cur_bytes, &cluster_offset);
+	if (ret < 0)
+		return -EINVAL;
+
+	offset_in_cluster = loop_file_fmt_qcow_offset_into_cluster(qcow_data,
+		offset);
+
+	len = sprintf(qcow_data->dbgfs_file_qcow_cluster_buf,
+		"offset: %lld\ncluster_offset: %lld\noffset_in_cluster: %lld\n",
+		offset, cluster_offset, offset_in_cluster);
+
+	ASSERT(len < QCOW_CLUSTER_BUF_LEN);
+
+	return simple_read_from_buffer(buf, size, ppos,
+		qcow_data->dbgfs_file_qcow_cluster_buf, len);
+}
+
+static ssize_t __qcow_file_fmt_dbgfs_ofs_write(struct file *file,
+	const char __user *buf, size_t size, loff_t *ppos)
+{
+	struct loop_file_fmt *lo_fmt = file->private_data;
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	ssize_t len = 0;
+	int ret = 0;
+
+	if (*ppos > QCOW_OFFSET_BUF_LEN || size > QCOW_OFFSET_BUF_LEN)
+		return -EINVAL;
+
+	len = simple_write_to_buffer(qcow_data->dbgfs_file_qcow_offset_buf,
+		QCOW_OFFSET_BUF_LEN, ppos, buf, size);
+	if (len < 0)
+		return len;
+
+	qcow_data->dbgfs_file_qcow_offset_buf[len] = '\0';
+
+	ret = mutex_lock_interruptible(&qcow_data->dbgfs_qcow_offset_mutex);
+	if (ret)
+		return ret;
+
+	ret = kstrtou64(qcow_data->dbgfs_file_qcow_offset_buf, 10,
+		&qcow_data->dbgfs_qcow_offset);
+	if (ret < 0)
+		goto out;
+
+	ret = len;
+out:
+	mutex_unlock(&qcow_data->dbgfs_qcow_offset_mutex);
+	return ret;
+}
+
+static const struct file_operations qcow_file_fmt_dbgfs_ofs_fops = {
+	.open = simple_open,
+	.read = __qcow_file_fmt_dbgfs_ofs_read,
+	.write = __qcow_file_fmt_dbgfs_ofs_write
+};
+
+static int __qcow_file_fmt_dbgfs_init(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	int ret = 0;
+
+	qcow_data->dbgfs_dir = debugfs_create_dir("QCOW", lo->lo_dbgfs_dir);
+	if (IS_ERR_OR_NULL(qcow_data->dbgfs_dir)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	qcow_data->dbgfs_file_qcow_header = debugfs_create_file("header",
+		S_IRUGO, qcow_data->dbgfs_dir, lo_fmt,
+		&qcow_file_fmt_dbgfs_hdr_fops);
+	if (IS_ERR_OR_NULL(qcow_data->dbgfs_file_qcow_header)) {
+		ret = -ENODEV;
+		goto out_free_dbgfs_dir;
+	}
+
+	qcow_data->dbgfs_file_qcow_offset = debugfs_create_file("offset",
+		S_IRUGO | S_IWUSR, qcow_data->dbgfs_dir, lo_fmt,
+		&qcow_file_fmt_dbgfs_ofs_fops);
+	if (IS_ERR_OR_NULL(qcow_data->dbgfs_file_qcow_offset)) {
+		qcow_data->dbgfs_file_qcow_offset = NULL;
+		ret = -ENODEV;
+		goto out_free_dbgfs_hdr;
+	}
+
+	qcow_data->dbgfs_qcow_offset = 0;
+	mutex_init(&qcow_data->dbgfs_qcow_offset_mutex);
+
+	return ret;
+
+out_free_dbgfs_hdr:
+	debugfs_remove(qcow_data->dbgfs_file_qcow_header);
+	qcow_data->dbgfs_file_qcow_header = NULL;
+out_free_dbgfs_dir:
+	debugfs_remove(qcow_data->dbgfs_dir);
+	qcow_data->dbgfs_dir = NULL;
+out:
+	return ret;
+}
+
+static void __qcow_file_fmt_dbgfs_exit(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+	if (qcow_data->dbgfs_file_qcow_offset)
+		debugfs_remove(qcow_data->dbgfs_file_qcow_offset);
+
+	mutex_destroy(&qcow_data->dbgfs_qcow_offset_mutex);
+
+	if (qcow_data->dbgfs_file_qcow_header)
+		debugfs_remove(qcow_data->dbgfs_file_qcow_header);
+
+	if (qcow_data->dbgfs_dir)
+		debugfs_remove(qcow_data->dbgfs_dir);
+}
+#endif
+
+static int qcow_file_fmt_init(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data;
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	struct loop_file_fmt_qcow_header header;
+	u64 l1_vm_state_index;
+	u64 l2_cache_size;
+	u64 l2_cache_entry_size;
+	ssize_t len;
+	unsigned int i;
+	int ret = 0;
+
+	/* allocate memory for saving QCOW file format data */
+	qcow_data = kzalloc(sizeof(*qcow_data), GFP_KERNEL);
+	if (!qcow_data)
+		return -ENOMEM;
+
+	lo_fmt->private_data = qcow_data;
+
+	/* read the QCOW file header */
+	ret = __qcow_file_fmt_header_read(lo_fmt, &header);
+	if (ret)
+		goto free_qcow_data;
+
+	/* save information of the header fields in human readable format in
+	 * a file buffer to access it with debugfs */
+#ifdef CONFIG_DEBUG_FS
+	__qcow_file_fmt_header_to_buf(lo_fmt, &header);
+#endif
+
+	qcow_data->qcow_version = header.version;
+
+	/* Initialise cluster size */
+	if (header.cluster_bits < QCOW_MIN_CLUSTER_BITS
+		|| header.cluster_bits > QCOW_MAX_CLUSTER_BITS) {
+		printk(KERN_ERR "loop_file_fmt_qcow: unsupported cluster "
+			"size: 2^%d", header.cluster_bits);
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+
+	qcow_data->cluster_bits = header.cluster_bits;
+	qcow_data->cluster_size = 1 << qcow_data->cluster_bits;
+	qcow_data->cluster_sectors = 1 <<
+		(qcow_data->cluster_bits - SECTOR_SHIFT);
+
+	if (header.header_length > qcow_data->cluster_size) {
+		printk(KERN_ERR "loop_file_fmt_qcow: QCOW header exceeds "
+			"cluster size");
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+
+	if (header.backing_file_offset > qcow_data->cluster_size) {
+		printk(KERN_ERR "loop_file_fmt_qcow: invalid backing file "
+			"offset");
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+
+	if (header.backing_file_offset) {
+		printk(KERN_ERR "loop_file_fmt_qcow: backing file support not "
+			"available");
+		ret = -ENOTSUPP;
+		goto free_qcow_data;
+	}
+
+	/* handle feature bits */
+	qcow_data->incompatible_features = header.incompatible_features;
+	qcow_data->compatible_features = header.compatible_features;
+	qcow_data->autoclear_features = header.autoclear_features;
+
+	if (qcow_data->incompatible_features & QCOW_INCOMPAT_DIRTY) {
+		printk(KERN_ERR "loop_file_fmt_qcow: image contains "
+			"inconsistent refcounts");
+		ret = -EACCES;
+		goto free_qcow_data;
+	}
+
+	if (qcow_data->incompatible_features & QCOW_INCOMPAT_CORRUPT) {
+		printk(KERN_ERR "loop_file_fmt_qcow: image is corrupt; cannot "
+			"be opened read/write");
+		ret = -EACCES;
+		goto free_qcow_data;
+	}
+
+	if (qcow_data->incompatible_features & QCOW_INCOMPAT_DATA_FILE) {
+		printk(KERN_ERR "loop_file_fmt_qcow: clusters in the external "
+			"data file are not refcounted");
+		ret = -EACCES;
+		goto free_qcow_data;
+	}
+
+	/* Check support for various header values */
+	if (header.refcount_order > 6) {
+		printk(KERN_ERR "loop_file_fmt_qcow: reference count entry "
+			"width too large; may not exceed 64 bits");
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+	qcow_data->refcount_order = header.refcount_order;
+	qcow_data->refcount_bits = 1 << qcow_data->refcount_order;
+	qcow_data->refcount_max = U64_C(1) << (qcow_data->refcount_bits - 1);
+	qcow_data->refcount_max += qcow_data->refcount_max - 1;
+
+	qcow_data->crypt_method_header = header.crypt_method;
+	if (qcow_data->crypt_method_header) {
+		printk(KERN_ERR "loop_file_fmt_qcow: encryption support not "
+			"available");
+		ret = -ENOTSUPP;
+		goto free_qcow_data;
+	}
+
+	/* L2 is always one cluster */
+	qcow_data->l2_bits = qcow_data->cluster_bits - 3;
+	qcow_data->l2_size = 1 << qcow_data->l2_bits;
+	/* 2^(qcow_data->refcount_order - 3) is the refcount width in bytes */
+	qcow_data->refcount_block_bits = qcow_data->cluster_bits -
+		(qcow_data->refcount_order - 3);
+	qcow_data->refcount_block_size = 1 << qcow_data->refcount_block_bits;
+	qcow_data->size = header.size;
+	qcow_data->csize_shift = (62 - (qcow_data->cluster_bits - 8));
+	qcow_data->csize_mask = (1 << (qcow_data->cluster_bits - 8)) - 1;
+	qcow_data->cluster_offset_mask = (1LL << qcow_data->csize_shift) - 1;
+
+	qcow_data->refcount_table_offset = header.refcount_table_offset;
+	qcow_data->refcount_table_size = header.refcount_table_clusters <<
+		(qcow_data->cluster_bits - 3);
+
+	if (header.refcount_table_clusters == 0) {
+		printk(KERN_ERR "loop_file_fmt_qcow: image does not contain a "
+			"reference count table");
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+
+	ret = __qcow_file_fmt_validate_table(lo_fmt,
+		qcow_data->refcount_table_offset,
+		header.refcount_table_clusters, qcow_data->cluster_size,
+		QCOW_MAX_REFTABLE_SIZE, "Reference count table");
+	if (ret < 0) {
+		goto free_qcow_data;
+	}
+
+	/* The total size in bytes of the snapshot table is checked in
+	 * qcow2_read_snapshots() because the size of each snapshot is
+	 * variable and we don't know it yet.
+	 * Here we only check the offset and number of snapshots. */
+	ret = __qcow_file_fmt_validate_table(lo_fmt, header.snapshots_offset,
+		header.nb_snapshots,
+		sizeof(struct loop_file_fmt_qcow_snapshot_header),
+		sizeof(struct loop_file_fmt_qcow_snapshot_header) *
+		QCOW_MAX_SNAPSHOTS, "Snapshot table");
+	if (ret < 0) {
+		goto free_qcow_data;
+	}
+
+	/* read the level 1 table */
+	ret = __qcow_file_fmt_validate_table(lo_fmt, header.l1_table_offset,
+		header.l1_size, sizeof(u64), QCOW_MAX_L1_SIZE,
+		"Active L1 table");
+	if (ret < 0) {
+		goto free_qcow_data;
+	}
+	qcow_data->l1_size = header.l1_size;
+	qcow_data->l1_table_offset = header.l1_table_offset;
+
+	l1_vm_state_index = loop_file_fmt_qcow_size_to_l1(qcow_data,
+		header.size);
+	if (l1_vm_state_index > INT_MAX) {
+		printk(KERN_ERR "loop_file_fmt_qcow: image is too big");
+		ret = -EFBIG;
+		goto free_qcow_data;
+	}
+	qcow_data->l1_vm_state_index = l1_vm_state_index;
+
+	/* the L1 table must contain at least enough entries to put header.size
+	 * bytes */
+	if (qcow_data->l1_size < qcow_data->l1_vm_state_index) {
+		printk(KERN_ERR "loop_file_fmt_qcow: L1 table is too small");
+		ret = -EINVAL;
+		goto free_qcow_data;
+	}
+
+	if (qcow_data->l1_size > 0) {
+		qcow_data->l1_table = vzalloc(round_up(qcow_data->l1_size *
+			sizeof(u64), 512));
+		if (qcow_data->l1_table == NULL) {
+			printk(KERN_ERR "loop_file_fmt_qcow: could not "
+				"allocate L1 table");
+			ret = -ENOMEM;
+			goto free_qcow_data;
+		}
+		len = kernel_read(lo->lo_backing_file, qcow_data->l1_table,
+			qcow_data->l1_size * sizeof(u64),
+			&qcow_data->l1_table_offset);
+		if (len < 0) {
+			printk(KERN_ERR "loop_file_fmt_qcow: could not read L1 "
+				"table");
+			ret = len;
+			goto free_l1_table;
+		}
+		for (i = 0; i < qcow_data->l1_size; i++) {
+			qcow_data->l1_table[i] =
+				be64_to_cpu(qcow_data->l1_table[i]);
+		}
+	}
+
+	/* Internal snapshots */
+	qcow_data->snapshots_offset = header.snapshots_offset;
+	qcow_data->nb_snapshots = header.nb_snapshots;
+
+	if (qcow_data->nb_snapshots > 0) {
+		printk(KERN_ERR "loop_file_fmt_qcow: snapshots support not "
+			"available");
+		ret = -ENOTSUPP;
+		goto free_l1_table;
+	}
+
+
+	/* create cache for L2 */
+	l2_cache_size =  qcow_data->size / (qcow_data->cluster_size / 8);
+	l2_cache_entry_size = min(qcow_data->cluster_size, (int)4096);
+
+	/* limit the L2 size to maximum QCOW_DEFAULT_L2_CACHE_MAX_SIZE */
+	l2_cache_size = min(l2_cache_size, (u64)QCOW_DEFAULT_L2_CACHE_MAX_SIZE);
+
+	/* calculate the number of cache tables */
+	l2_cache_size /= l2_cache_entry_size;
+	if (l2_cache_size < QCOW_MIN_L2_CACHE_SIZE) {
+		l2_cache_size = QCOW_MIN_L2_CACHE_SIZE;
+	}
+
+	if (l2_cache_size > INT_MAX) {
+		printk(KERN_ERR "loop_file_fmt_qcow: L2 cache size too big");
+		ret = -EINVAL;
+		goto free_l1_table;
+	}
+
+	qcow_data->l2_slice_size = l2_cache_entry_size / sizeof(u64);
+
+	qcow_data->l2_table_cache = loop_file_fmt_qcow_cache_create(lo_fmt,
+		l2_cache_size, l2_cache_entry_size);
+	if (!qcow_data->l2_table_cache) {
+		ret = -ENOMEM;
+		goto free_l1_table;
+	}
+
+	/* initialize compression support */
+	ret = __qcow_file_fmt_compression_init(lo_fmt);
+	if (ret < 0)
+		goto free_l2_cache;
+
+	/* initialize debugfs entries */
+#ifdef CONFIG_DEBUG_FS
+	ret = __qcow_file_fmt_dbgfs_init(lo_fmt);
+	if (ret < 0)
+		goto free_l2_cache;
+#endif
+
+	return ret;
+
+free_l2_cache:
+	loop_file_fmt_qcow_cache_destroy(lo_fmt);
+free_l1_table:
+	vfree(qcow_data->l1_table);
+free_qcow_data:
+	kfree(qcow_data);
+	lo_fmt->private_data = NULL;
+	return ret;
+}
+
+static void qcow_file_fmt_exit(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+
+#ifdef CONFIG_DEBUG_FS
+	__qcow_file_fmt_dbgfs_exit(lo_fmt);
+#endif
+
+	__qcow_file_fmt_compression_exit(lo_fmt);
+
+	if (qcow_data->l1_table) {
+		vfree(qcow_data->l1_table);
+	}
+
+	if (qcow_data->l2_table_cache) {
+		loop_file_fmt_qcow_cache_destroy(lo_fmt);
+	}
+
+	if (qcow_data) {
+		kfree(qcow_data);
+		lo_fmt->private_data = NULL;
+	}
+}
+
+static ssize_t __qcow_file_fmt_buffer_decompress(struct loop_file_fmt *lo_fmt,
+						 void *dest,
+						 size_t dest_size,
+						 const void *src,
+						 size_t src_size)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	int ret = 0;
+
+	qcow_data->strm->avail_in = src_size;
+	qcow_data->strm->next_in = (void *) src;
+	qcow_data->strm->avail_out = dest_size;
+	qcow_data->strm->next_out = dest;
+
+	ret = zlib_inflateInit2(qcow_data->strm, -12);
+	if (ret != Z_OK) {
+		return -1;
+	}
+
+	ret = zlib_inflate(qcow_data->strm, Z_FINISH);
+	if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR)
+		|| qcow_data->strm->avail_out != 0) {
+		/* We approve Z_BUF_ERROR because we need @dest buffer to be
+		 * filled, but @src buffer may be processed partly (because in
+		 * qcow2 we know size of compressed data with precision of one
+		 * sector) */
+		ret = -1;
+	}
+
+	zlib_inflateEnd(qcow_data->strm);
+
+	return ret;
+}
+
+static int __qcow_file_fmt_read_compressed(struct loop_file_fmt *lo_fmt,
+					   struct bio_vec *bvec,
+					   u64 file_cluster_offset,
+					   u64 offset,
+					   u64 bytes,
+					   u64 bytes_done)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	int ret = 0, csize, nb_csectors;
+	u64 coffset;
+	u8 *in_buf, *out_buf;
+	ssize_t len;
+	void *data;
+	unsigned long irq_flags;
+	int offset_in_cluster = loop_file_fmt_qcow_offset_into_cluster(
+		qcow_data, offset);
+
+	coffset = file_cluster_offset & qcow_data->cluster_offset_mask;
+	nb_csectors = ((file_cluster_offset >> qcow_data->csize_shift) &
+		qcow_data->csize_mask) + 1;
+	csize = nb_csectors * QCOW_COMPRESSED_SECTOR_SIZE -
+		(coffset & ~QCOW_COMPRESSED_SECTOR_MASK);
+
+	in_buf = vmalloc(csize);
+	if (!in_buf) {
+		return -ENOMEM;
+	}
+
+	out_buf = vmalloc(qcow_data->cluster_size);
+	if (!out_buf) {
+		ret = -ENOMEM;
+		goto out_free_in_buf;
+	}
+
+	len = kernel_read(lo->lo_backing_file, in_buf, csize, &coffset);
+	if (len < 0) {
+		ret = len;
+		goto out_free_out_buf;
+	}
+
+	if (__qcow_file_fmt_buffer_decompress(lo_fmt, out_buf,
+		qcow_data->cluster_size, in_buf, csize) < 0) {
+		ret = -EIO;
+		goto out_free_out_buf;
+	}
+
+	ASSERT(bytes <= bvec->bv_len);
+	data = bvec_kmap_irq(bvec, &irq_flags) + bytes_done;
+	memcpy(data, out_buf + offset_in_cluster, bytes);
+	flush_dcache_page(bvec->bv_page);
+	bvec_kunmap_irq(data, &irq_flags);
+
+out_free_out_buf:
+	vfree(out_buf);
+out_free_in_buf:
+	vfree(in_buf);
+
+	return ret;
+}
+
+static int __qcow_file_fmt_read_bvec(struct loop_file_fmt *lo_fmt,
+				     struct bio_vec *bvec,
+				     loff_t *ppos)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	int offset_in_cluster;
+	int ret;
+	unsigned int cur_bytes; /* number of bytes in current iteration */
+	u64 bytes;
+	u64 cluster_offset = 0;
+	u64 bytes_done = 0;
+	void *data;
+	unsigned long irq_flags;
+	ssize_t len;
+	loff_t pos_read;
+
+	bytes = bvec->bv_len;
+
+	while (bytes != 0) {
+
+		/* prepare next request */
+		cur_bytes = bytes;
+
+		ret = loop_file_fmt_qcow_cluster_get_offset(lo_fmt, *ppos,
+			&cur_bytes, &cluster_offset);
+		if (ret < 0) {
+			goto fail;
+		}
+
+		offset_in_cluster = loop_file_fmt_qcow_offset_into_cluster(
+			qcow_data, *ppos);
+
+		switch (ret) {
+		case QCOW_CLUSTER_UNALLOCATED:
+		case QCOW_CLUSTER_ZERO_PLAIN:
+		case QCOW_CLUSTER_ZERO_ALLOC:
+			data = bvec_kmap_irq(bvec, &irq_flags) + bytes_done;
+			memset(data, 0, cur_bytes);
+			flush_dcache_page(bvec->bv_page);
+			bvec_kunmap_irq(data, &irq_flags);
+			break;
+
+		case QCOW_CLUSTER_COMPRESSED:
+			ret = __qcow_file_fmt_read_compressed(lo_fmt, bvec,
+				cluster_offset, *ppos, cur_bytes, bytes_done);
+			if (ret < 0) {
+				goto fail;
+			}
+
+			break;
+
+		case QCOW_CLUSTER_NORMAL:
+			if ((cluster_offset & 511) != 0) {
+				ret = -EIO;
+				goto fail;
+			}
+
+			pos_read = cluster_offset + offset_in_cluster;
+
+			data = bvec_kmap_irq(bvec, &irq_flags) + bytes_done;
+			len = kernel_read(lo->lo_backing_file, data, cur_bytes,
+				&pos_read);
+			flush_dcache_page(bvec->bv_page);
+			bvec_kunmap_irq(data, &irq_flags);
+
+			if (len < 0)
+				return len;
+
+			break;
+
+		default:
+			ret = -EIO;
+			goto fail;
+		}
+
+		bytes -= cur_bytes;
+		*ppos += cur_bytes;
+		bytes_done += cur_bytes;
+	}
+
+	ret = 0;
+
+fail:
+	return ret;
+}
+
+static int qcow_file_fmt_read(struct loop_file_fmt *lo_fmt,
+			      struct request *rq)
+{
+	struct bio_vec bvec;
+	struct req_iterator iter;
+	loff_t pos;
+	int ret = 0;
+
+	pos = __qcow_file_fmt_rq_get_pos(lo_fmt, rq);
+
+	rq_for_each_segment(bvec, rq, iter) {
+		ret = __qcow_file_fmt_read_bvec(lo_fmt, &bvec, &pos);
+		if (ret)
+			return ret;
+
+		cond_resched();
+	}
+
+	return ret;
+}
+
+static loff_t qcow_file_fmt_sector_size(struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct loop_device *lo = loop_file_fmt_get_lo(lo_fmt);
+	loff_t loopsize;
+
+	if (qcow_data->size > 0)
+		loopsize = qcow_data->size;
+	else
+		return 0;
+
+	if (lo->lo_offset > 0)
+		loopsize -= lo->lo_offset;
+
+	if (lo->lo_sizelimit > 0 && lo->lo_sizelimit < loopsize)
+		loopsize = lo->lo_sizelimit;
+
+	/*
+	 * Unfortunately, if we want to do I/O on the device,
+	 * the number of 512-byte sectors has to fit into a sector_t.
+	 */
+	return loopsize >> 9;
+}
+
+static struct loop_file_fmt_ops qcow_file_fmt_ops = {
+	.init = qcow_file_fmt_init,
+	.exit = qcow_file_fmt_exit,
+	.read = qcow_file_fmt_read,
+	.write = NULL,
+	.read_aio = NULL,
+	.write_aio = NULL,
+	.discard = NULL,
+	.flush = NULL,
+	.sector_size = qcow_file_fmt_sector_size
+};
+
+static struct loop_file_fmt_driver qcow_file_fmt_driver = {
+	.name = "QCOW",
+	.file_fmt_type = LO_FILE_FMT_QCOW,
+	.ops = &qcow_file_fmt_ops,
+	.owner = THIS_MODULE
+};
+
+static int __init loop_file_fmt_qcow_init(void)
+{
+	printk(KERN_INFO "loop_file_fmt_qcow: init loop device QCOW file "
+		"format driver");
+	return loop_file_fmt_register_driver(&qcow_file_fmt_driver);
+}
+
+static void __exit loop_file_fmt_qcow_exit(void)
+{
+	printk(KERN_INFO "loop_file_fmt_qcow: exit loop device QCOW file "
+		"format driver");
+	loop_file_fmt_unregister_driver(&qcow_file_fmt_driver);
+}
+
+module_init(loop_file_fmt_qcow_init);
+module_exit(loop_file_fmt_qcow_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Manuel Bentele <development@manuel-bentele.de>");
+MODULE_DESCRIPTION("Loop device QCOW file format driver");
+MODULE_SOFTDEP("pre: loop");
diff --git a/drivers/block/loop/loop_file_fmt_qcow_main.h b/drivers/block/loop/loop_file_fmt_qcow_main.h
new file mode 100644
index 000000000000..9e4951fba079
--- /dev/null
+++ b/drivers/block/loop/loop_file_fmt_qcow_main.h
@@ -0,0 +1,417 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * loop_file_fmt_qcow.h
+ *
+ * QCOW file format driver for the loop device module.
+ *
+ * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
+ * Declarations for the QCOW2 file format.
+ *
+ * The copyright (C) 2004-2006 of the original code is owned by Fabrice Bellard.
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#ifndef _LINUX_LOOP_FILE_FMT_QCOW_H
+#define _LINUX_LOOP_FILE_FMT_QCOW_H
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <linux/zlib.h>
+
+#ifdef CONFIG_DEBUG_FS
+#include <linux/debugfs.h>
+#endif
+
+#include "loop_file_fmt.h"
+
+#ifdef CONFIG_DEBUG_DRIVER
+#define ASSERT(x)  							\
+do {									\
+	if (!(x)) {							\
+		printk(KERN_EMERG "assertion failed %s: %d: %s\n",	\
+		       __FILE__, __LINE__, #x);				\
+		BUG();							\
+	}								\
+} while (0)
+#else
+#define ASSERT(x) do { } while (0)
+#endif
+
+#define KiB (1024)
+#define MiB (1024 * 1024)
+
+#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
+
+#define QCOW_CRYPT_NONE 0
+#define QCOW_CRYPT_AES  1
+#define QCOW_CRYPT_LUKS 2
+
+#define QCOW_MAX_CRYPT_CLUSTERS 32
+#define QCOW_MAX_SNAPSHOTS 65536
+
+/* Field widths in QCOW mean normal cluster offsets cannot reach
+ * 64PB; depending on cluster size, compressed clusters can have a
+ * smaller limit (64PB for up to 16k clusters, then ramps down to
+ * 512TB for 2M clusters).  */
+#define QCOW_MAX_CLUSTER_OFFSET ((1ULL << 56) - 1)
+
+/* 8 MB refcount table is enough for 2 PB images at 64k cluster size
+ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
+#define QCOW_MAX_REFTABLE_SIZE (8 * MiB)
+
+/* 32 MB L1 table is enough for 2 PB images at 64k cluster size
+ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
+#define QCOW_MAX_L1_SIZE (32 * MiB)
+
+/* Allow for an average of 1k per snapshot table entry, should be plenty of
+ * space for snapshot names and IDs */
+#define QCOW_MAX_SNAPSHOTS_SIZE (1024 * QCOW_MAX_SNAPSHOTS)
+
+/* Bitmap header extension constraints */
+#define QCOW_MAX_BITMAPS 65535
+#define QCOW_MAX_BITMAP_DIRECTORY_SIZE (1024 * QCOW_MAX_BITMAPS)
+
+/* indicate that the refcount of the referenced cluster is exactly one. */
+#define QCOW_OFLAG_COPIED     (1ULL << 63)
+/* indicate that the cluster is compressed (they never have the copied flag) */
+#define QCOW_OFLAG_COMPRESSED (1ULL << 62)
+/* The cluster reads as all zeros */
+#define QCOW_OFLAG_ZERO (1ULL << 0)
+
+#define QCOW_MIN_CLUSTER_BITS 9
+#define QCOW_MAX_CLUSTER_BITS 21
+
+/* Defined in the qcow2 spec (compressed cluster descriptor) */
+#define QCOW_COMPRESSED_SECTOR_SIZE 512U
+#define QCOW_COMPRESSED_SECTOR_MASK (~(QCOW_COMPRESSED_SECTOR_SIZE - 1))
+
+/* Must be at least 2 to cover COW */
+#define QCOW_MIN_L2_CACHE_SIZE 2 /* cache entries */
+
+/* Must be at least 4 to cover all cases of refcount table growth */
+#define QCOW_MIN_REFCOUNT_CACHE_SIZE 4 /* clusters */
+
+#define QCOW_DEFAULT_L2_CACHE_MAX_SIZE (32 * MiB)
+#define QCOW_DEFAULT_CACHE_CLEAN_INTERVAL 600  /* seconds */
+
+#define QCOW_DEFAULT_CLUSTER_SIZE 65536
+
+/* Buffer size for debugfs file buffer to display QCOW header information */
+#define QCOW_HEADER_BUF_LEN 1024
+
+/* Buffer size for debugfs file buffer to receive and display offset and
+ * cluster offset information */
+#define QCOW_OFFSET_BUF_LEN 32
+#define QCOW_CLUSTER_BUF_LEN 128
+
+struct loop_file_fmt_qcow_header {
+	u32 magic;
+	u32 version;
+	u64 backing_file_offset;
+	u32 backing_file_size;
+	u32 cluster_bits;
+	u64 size; /* in bytes */
+	u32 crypt_method;
+	u32 l1_size;
+	u64 l1_table_offset;
+	u64 refcount_table_offset;
+	u32 refcount_table_clusters;
+	u32 nb_snapshots;
+	u64 snapshots_offset;
+
+	/* The following fields are only valid for version >= 3 */
+	u64 incompatible_features;
+	u64 compatible_features;
+	u64 autoclear_features;
+
+	u32 refcount_order;
+	u32 header_length;
+} __attribute__((packed));
+
+struct loop_file_fmt_qcow_snapshot_header {
+	/* header is 8 byte aligned */
+	u64 l1_table_offset;
+
+	u32 l1_size;
+	u16 id_str_size;
+	u16 name_size;
+
+	u32 date_sec;
+	u32 date_nsec;
+
+	u64 vm_clock_nsec;
+
+	u32 vm_state_size;
+	/* for extension */
+	u32 extra_data_size;
+	/* extra data follows */
+	/* id_str follows */
+	/* name follows  */
+} __attribute__((packed));
+
+enum {
+	QCOW_FEAT_TYPE_INCOMPATIBLE    = 0,
+	QCOW_FEAT_TYPE_COMPATIBLE      = 1,
+	QCOW_FEAT_TYPE_AUTOCLEAR       = 2,
+};
+
+/* incompatible feature bits */
+enum {
+	QCOW_INCOMPAT_DIRTY_BITNR      = 0,
+	QCOW_INCOMPAT_CORRUPT_BITNR    = 1,
+	QCOW_INCOMPAT_DATA_FILE_BITNR  = 2,
+	QCOW_INCOMPAT_DIRTY            = 1 << QCOW_INCOMPAT_DIRTY_BITNR,
+	QCOW_INCOMPAT_CORRUPT          = 1 << QCOW_INCOMPAT_CORRUPT_BITNR,
+	QCOW_INCOMPAT_DATA_FILE        = 1 << QCOW_INCOMPAT_DATA_FILE_BITNR,
+
+	QCOW_INCOMPAT_MASK             = QCOW_INCOMPAT_DIRTY
+					| QCOW_INCOMPAT_CORRUPT
+					| QCOW_INCOMPAT_DATA_FILE,
+};
+
+/* compatible feature bits */
+enum {
+	QCOW_COMPAT_LAZY_REFCOUNTS_BITNR = 0,
+	QCOW_COMPAT_LAZY_REFCOUNTS       = 1 << QCOW_COMPAT_LAZY_REFCOUNTS_BITNR,
+
+	QCOW_COMPAT_FEAT_MASK            = QCOW_COMPAT_LAZY_REFCOUNTS,
+};
+
+/* autoclear feature bits */
+enum {
+	QCOW_AUTOCLEAR_BITMAPS_BITNR       = 0,
+	QCOW_AUTOCLEAR_DATA_FILE_RAW_BITNR = 1,
+	QCOW_AUTOCLEAR_BITMAPS             = 1 << QCOW_AUTOCLEAR_BITMAPS_BITNR,
+	QCOW_AUTOCLEAR_DATA_FILE_RAW       = 1 << QCOW_AUTOCLEAR_DATA_FILE_RAW_BITNR,
+
+	QCOW_AUTOCLEAR_MASK                = QCOW_AUTOCLEAR_BITMAPS |
+						QCOW_AUTOCLEAR_DATA_FILE_RAW,
+};
+
+struct loop_file_fmt_qcow_data {
+	u64 size;
+	int cluster_bits;
+	int cluster_size;
+	int cluster_sectors;
+	int l2_slice_size;
+	int l2_bits;
+	int l2_size;
+	int l1_size;
+	int l1_vm_state_index;
+	int refcount_block_bits;
+	int refcount_block_size;
+	int csize_shift;
+	int csize_mask;
+	u64 cluster_offset_mask;
+	u64 l1_table_offset;
+	u64 *l1_table;
+
+	struct loop_file_fmt_qcow_cache *l2_table_cache;
+	struct loop_file_fmt_qcow_cache *refcount_block_cache;
+
+	u64 *refcount_table;
+	u64 refcount_table_offset;
+	u32 refcount_table_size;
+	u32 max_refcount_table_index; /* Last used entry in refcount_table */
+	u64 free_cluster_index;
+	u64 free_byte_offset;
+
+	u32 crypt_method_header;
+	u64 snapshots_offset;
+	int snapshots_size;
+	unsigned int nb_snapshots;
+
+	u32 nb_bitmaps;
+	u64 bitmap_directory_size;
+	u64 bitmap_directory_offset;
+
+	int qcow_version;
+	bool use_lazy_refcounts;
+	int refcount_order;
+	int refcount_bits;
+	u64 refcount_max;
+
+	u64 incompatible_features;
+	u64 compatible_features;
+	u64 autoclear_features;
+
+	struct z_stream_s *strm;
+
+	/* debugfs entries */
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *dbgfs_dir;
+	struct dentry *dbgfs_file_qcow_header;
+	char dbgfs_file_qcow_header_buf[QCOW_HEADER_BUF_LEN];
+	struct dentry *dbgfs_file_qcow_offset;
+	char dbgfs_file_qcow_offset_buf[QCOW_OFFSET_BUF_LEN];
+	char dbgfs_file_qcow_cluster_buf[QCOW_CLUSTER_BUF_LEN];
+	u64 dbgfs_qcow_offset;
+	struct mutex dbgfs_qcow_offset_mutex;
+#endif
+};
+
+struct loop_file_fmt_qcow_cow_region {
+	/**
+	 * Offset of the COW region in bytes from the start of the first
+	 * cluster touched by the request.
+	 */
+	unsigned offset;
+
+	/** Number of bytes to copy */
+	unsigned nb_bytes;
+};
+
+enum loop_file_fmt_qcow_cluster_type {
+	QCOW_CLUSTER_UNALLOCATED,
+	QCOW_CLUSTER_ZERO_PLAIN,
+	QCOW_CLUSTER_ZERO_ALLOC,
+	QCOW_CLUSTER_NORMAL,
+	QCOW_CLUSTER_COMPRESSED,
+};
+
+enum loop_file_fmt_qcow_metadata_overlap {
+	QCOW_OL_MAIN_HEADER_BITNR      = 0,
+	QCOW_OL_ACTIVE_L1_BITNR        = 1,
+	QCOW_OL_ACTIVE_L2_BITNR        = 2,
+	QCOW_OL_REFCOUNT_TABLE_BITNR   = 3,
+	QCOW_OL_REFCOUNT_BLOCK_BITNR   = 4,
+	QCOW_OL_SNAPSHOT_TABLE_BITNR   = 5,
+	QCOW_OL_INACTIVE_L1_BITNR      = 6,
+	QCOW_OL_INACTIVE_L2_BITNR      = 7,
+	QCOW_OL_BITMAP_DIRECTORY_BITNR = 8,
+
+	QCOW_OL_MAX_BITNR              = 9,
+
+	QCOW_OL_NONE             = 0,
+	QCOW_OL_MAIN_HEADER      = (1 << QCOW_OL_MAIN_HEADER_BITNR),
+	QCOW_OL_ACTIVE_L1        = (1 << QCOW_OL_ACTIVE_L1_BITNR),
+	QCOW_OL_ACTIVE_L2        = (1 << QCOW_OL_ACTIVE_L2_BITNR),
+	QCOW_OL_REFCOUNT_TABLE   = (1 << QCOW_OL_REFCOUNT_TABLE_BITNR),
+	QCOW_OL_REFCOUNT_BLOCK   = (1 << QCOW_OL_REFCOUNT_BLOCK_BITNR),
+	QCOW_OL_SNAPSHOT_TABLE   = (1 << QCOW_OL_SNAPSHOT_TABLE_BITNR),
+	QCOW_OL_INACTIVE_L1      = (1 << QCOW_OL_INACTIVE_L1_BITNR),
+	/* NOTE: Checking overlaps with inactive L2 tables will result in bdrv
+	 * reads. */
+	QCOW_OL_INACTIVE_L2      = (1 << QCOW_OL_INACTIVE_L2_BITNR),
+	QCOW_OL_BITMAP_DIRECTORY = (1 << QCOW_OL_BITMAP_DIRECTORY_BITNR),
+};
+
+/* Perform all overlap checks which can be done in constant time */
+#define QCOW_OL_CONSTANT \
+	(QCOW_OL_MAIN_HEADER | QCOW_OL_ACTIVE_L1 | QCOW_OL_REFCOUNT_TABLE | \
+		QCOW_OL_SNAPSHOT_TABLE | QCOW_OL_BITMAP_DIRECTORY)
+
+/* Perform all overlap checks which don't require disk access */
+#define QCOW_OL_CACHED \
+	(QCOW_OL_CONSTANT | QCOW_OL_ACTIVE_L2 | QCOW_OL_REFCOUNT_BLOCK | \
+		QCOW_OL_INACTIVE_L1)
+
+/* Perform all overlap checks */
+#define QCOW_OL_ALL \
+	(QCOW_OL_CACHED | QCOW_OL_INACTIVE_L2)
+
+#define L1E_OFFSET_MASK 0x00fffffffffffe00ULL
+#define L2E_OFFSET_MASK 0x00fffffffffffe00ULL
+#define L2E_COMPRESSED_OFFSET_SIZE_MASK 0x3fffffffffffffffULL
+
+#define REFT_OFFSET_MASK 0xfffffffffffffe00ULL
+
+#define INV_OFFSET (-1ULL)
+
+static inline bool loop_file_fmt_qcow_has_data_file(
+	struct loop_file_fmt *lo_fmt)
+{
+	/* At the moment, there is no support for copy on write! */
+	return false;
+}
+
+static inline bool loop_file_fmt_qcow_data_file_is_raw(
+	struct loop_file_fmt *lo_fmt)
+{
+	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	return !!(qcow_data->autoclear_features &
+		QCOW_AUTOCLEAR_DATA_FILE_RAW);
+}
+
+static inline s64 loop_file_fmt_qcow_start_of_cluster(
+	struct loop_file_fmt_qcow_data *qcow_data, s64 offset)
+{
+	return offset & ~(qcow_data->cluster_size - 1);
+}
+
+static inline s64 loop_file_fmt_qcow_offset_into_cluster(
+	struct loop_file_fmt_qcow_data *qcow_data, s64 offset)
+{
+	return offset & (qcow_data->cluster_size - 1);
+}
+
+static inline s64 loop_file_fmt_qcow_size_to_clusters(
+	struct loop_file_fmt_qcow_data *qcow_data, u64 size)
+{
+	return (size + (qcow_data->cluster_size - 1)) >>
+		qcow_data->cluster_bits;
+}
+
+static inline s64 loop_file_fmt_qcow_size_to_l1(
+	struct loop_file_fmt_qcow_data *qcow_data, s64 size)
+{
+	int shift = qcow_data->cluster_bits + qcow_data->l2_bits;
+	return (size + (1ULL << shift) - 1) >> shift;
+}
+
+static inline int loop_file_fmt_qcow_offset_to_l1_index(
+	struct loop_file_fmt_qcow_data *qcow_data, u64 offset)
+{
+	return offset >> (qcow_data->l2_bits + qcow_data->cluster_bits);
+}
+
+static inline int loop_file_fmt_qcow_offset_to_l2_index(
+	struct loop_file_fmt_qcow_data *qcow_data, s64 offset)
+{
+	return (offset >> qcow_data->cluster_bits) & (qcow_data->l2_size - 1);
+}
+
+static inline int loop_file_fmt_qcow_offset_to_l2_slice_index(
+	struct loop_file_fmt_qcow_data *qcow_data, s64 offset)
+{
+	return (offset >> qcow_data->cluster_bits) &
+		(qcow_data->l2_slice_size - 1);
+}
+
+static inline s64 loop_file_fmt_qcow_vm_state_offset(
+	struct loop_file_fmt_qcow_data *qcow_data)
+{
+	return (s64)qcow_data->l1_vm_state_index <<
+		(qcow_data->cluster_bits + qcow_data->l2_bits);
+}
+
+static inline enum loop_file_fmt_qcow_cluster_type
+loop_file_fmt_qcow_get_cluster_type(struct loop_file_fmt *lo_fmt, u64 l2_entry)
+{
+	if (l2_entry & QCOW_OFLAG_COMPRESSED) {
+		return QCOW_CLUSTER_COMPRESSED;
+	} else if (l2_entry & QCOW_OFLAG_ZERO) {
+		if (l2_entry & L2E_OFFSET_MASK) {
+			return QCOW_CLUSTER_ZERO_ALLOC;
+		}
+		return QCOW_CLUSTER_ZERO_PLAIN;
+	} else if (!(l2_entry & L2E_OFFSET_MASK)) {
+		/* Offset 0 generally means unallocated, but it is ambiguous
+		 * with external data files because 0 is a valid offset there.
+		 * However, all clusters in external data files always have
+		 * refcount 1, so we can rely on QCOW_OFLAG_COPIED to
+		 * disambiguate. */
+		if (loop_file_fmt_qcow_has_data_file(lo_fmt) &&
+			(l2_entry & QCOW_OFLAG_COPIED)) {
+			return QCOW_CLUSTER_NORMAL;
+		} else {
+			return QCOW_CLUSTER_UNALLOCATED;
+		}
+	} else {
+		return QCOW_CLUSTER_NORMAL;
+	}
+}
+
+#endif
