Added file format file format subsystem for loop devices

The loop device module is extended by a file format subsystem to allow the
implementation of various disk file formats. The file format drivers are
implemented as own kernel modules and registered by the subsystem. The
subsystem takes control over the specified file format at loop creation and
calls the corresponding file format driver functions.

At the moment, the file format subsystem can handle ...

  - read
  - write
  - discard
  - flush
  - sector size

... operations of loop devices.

The file format of each loop device can be specified by the LOOP_CONFIGURE
LOOP_SET_STATUS or LOOP_SET_STATUS64 ioctl with the corresponding data
structure loop_info or respectively loop_info64.

1 files changed, 36 insertions, 36 deletions

diff --git a/loop_file_fmt_qcow_main.h b/loop_file_fmt_qcow_main.h
index dd6ed30..54b94c3 100644
--- a/loop_file_fmt_qcow_main.h
+++ b/loop_file_fmt_qcow_main.h
@@ -1,8 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
- * loop_file_fmt_qcow.h
+ * xloop_file_fmt_qcow.h
  *
- * QCOW file format driver for the loop device module.
+ * QCOW file format driver for the xloop device module.
  *
  * Ported QCOW2 implementation of the QEMU project (GPL-2.0):
  * Declarations for the QCOW2 file format.
@@ -12,8 +12,8 @@
  * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
  */
 
-#ifndef _LINUX_LOOP_FILE_FMT_QCOW_H
-#define _LINUX_LOOP_FILE_FMT_QCOW_H
+#ifndef _LINUX_XLOOP_FILE_FMT_QCOW_H
+#define _LINUX_XLOOP_FILE_FMT_QCOW_H
 
 #include <linux/list.h>
 #include <linux/mutex.h>
@@ -106,7 +106,7 @@ do {									\
 #define QCOW_OFFSET_BUF_LEN 32
 #define QCOW_CLUSTER_BUF_LEN 128
 
-struct loop_file_fmt_qcow_header {
+struct xloop_file_fmt_qcow_header {
 	u32 magic;
 	u32 version;
 	u64 backing_file_offset;
@@ -130,7 +130,7 @@ struct loop_file_fmt_qcow_header {
 	u32 header_length;
 } __attribute__((packed));
 
-struct loop_file_fmt_qcow_snapshot_header {
+struct xloop_file_fmt_qcow_snapshot_header {
 	/* header is 8 byte aligned */
 	u64 l1_table_offset;
 
@@ -190,7 +190,7 @@ enum {
 						QCOW_AUTOCLEAR_DATA_FILE_RAW,
 };
 
-struct loop_file_fmt_qcow_data {
+struct xloop_file_fmt_qcow_data {
 	u64 size;
 	int cluster_bits;
 	int cluster_size;
@@ -208,8 +208,8 @@ struct loop_file_fmt_qcow_data {
 	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;
+	struct xloop_file_fmt_qcow_cache *l2_table_cache;
+	struct xloop_file_fmt_qcow_cache *refcount_block_cache;
 
 	u64 *refcount_table;
 	u64 refcount_table_offset;
@@ -254,7 +254,7 @@ struct loop_file_fmt_qcow_data {
 #endif
 };
 
-struct loop_file_fmt_qcow_cow_region {
+struct xloop_file_fmt_qcow_cow_region {
 	/**
 	 * Offset of the COW region in bytes from the start of the first
 	 * cluster touched by the request.
@@ -265,7 +265,7 @@ struct loop_file_fmt_qcow_cow_region {
 	unsigned nb_bytes;
 };
 
-enum loop_file_fmt_qcow_cluster_type {
+enum xloop_file_fmt_qcow_cluster_type {
 	QCOW_CLUSTER_UNALLOCATED,
 	QCOW_CLUSTER_ZERO_PLAIN,
 	QCOW_CLUSTER_ZERO_ALLOC,
@@ -273,7 +273,7 @@ enum loop_file_fmt_qcow_cluster_type {
 	QCOW_CLUSTER_COMPRESSED,
 };
 
-enum loop_file_fmt_qcow_metadata_overlap {
+enum xloop_file_fmt_qcow_metadata_overlap {
 	QCOW_OL_MAIN_HEADER_BITNR      = 0,
 	QCOW_OL_ACTIVE_L1_BITNR        = 1,
 	QCOW_OL_ACTIVE_L2_BITNR        = 2,
@@ -322,75 +322,75 @@ enum loop_file_fmt_qcow_metadata_overlap {
 
 #define INV_OFFSET (-1ULL)
 
-static inline bool loop_file_fmt_qcow_has_data_file(
-	struct loop_file_fmt *lo_fmt)
+static inline bool xloop_file_fmt_qcow_has_data_file(
+	struct xloop_file_fmt *xlo_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)
+static inline bool xloop_file_fmt_qcow_data_file_is_raw(
+	struct xloop_file_fmt *xlo_fmt)
 {
-	struct loop_file_fmt_qcow_data *qcow_data = lo_fmt->private_data;
+	struct xloop_file_fmt_qcow_data *qcow_data = xlo_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)
+static inline s64 xloop_file_fmt_qcow_start_of_cluster(
+	struct xloop_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)
+static inline s64 xloop_file_fmt_qcow_offset_into_cluster(
+	struct xloop_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)
+static inline s64 xloop_file_fmt_qcow_size_to_clusters(
+	struct xloop_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)
+static inline s64 xloop_file_fmt_qcow_size_to_l1(
+	struct xloop_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)
+static inline int xloop_file_fmt_qcow_offset_to_l1_index(
+	struct xloop_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)
+static inline int xloop_file_fmt_qcow_offset_to_l2_index(
+	struct xloop_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)
+static inline int xloop_file_fmt_qcow_offset_to_l2_slice_index(
+	struct xloop_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)
+static inline s64 xloop_file_fmt_qcow_vm_state_offset(
+	struct xloop_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)
+static inline enum xloop_file_fmt_qcow_cluster_type
+xloop_file_fmt_qcow_get_cluster_type(struct xloop_file_fmt *xlo_fmt, u64 l2_entry)
 {
 	if (l2_entry & QCOW_OFLAG_COMPRESSED) {
 		return QCOW_CLUSTER_COMPRESSED;
@@ -405,7 +405,7 @@ loop_file_fmt_qcow_get_cluster_type(struct loop_file_fmt *lo_fmt, u64 l2_entry)
 		 * 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) &&
+		if (xloop_file_fmt_qcow_has_data_file(xlo_fmt) &&
 			(l2_entry & QCOW_OFLAG_COPIED)) {
 			return QCOW_CLUSTER_NORMAL;
 		} else {