1 files changed, 388 insertions, 0 deletions
diff --git a/src/kernel/xloop_file_fmt.h b/src/kernel/xloop_file_fmt.h
new file mode 100644
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+++ b/src/kernel/xloop_file_fmt.h
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * xloop_file_fmt.h
+ *
+ * File format subsystem for the xloop device module.
+ *
+ * Copyright (C) 2019 Manuel Bentele <development@manuel-bentele.de>
+ */
+
+#ifndef _LINUX_XLOOP_FILE_FMT_H
+#define _LINUX_XLOOP_FILE_FMT_H
+
+#include "xloop_main.h"
+
+struct xloop_file_fmt;
+
+#define XLO_FILE_FMT_RAW         0
+#define XLO_FILE_FMT_QCOW        1
+#define XLO_FILE_FMT_VDI         2
+#define XLO_FILE_FMT_VMDK        3
+#define MAX_XLO_FILE_FMT         (XLO_FILE_FMT_VMDK + 1)
+
+/**
+ * struct xloop_file_fmt_ops - File format subsystem operations
+ *
+ * Data structure representing the file format subsystem interface.
+ */
+struct xloop_file_fmt_ops {
+	/**
+	 * @init: Initialization callback function
+	 */
+	int (*init) (struct xloop_file_fmt *xlo_fmt);
+
+	/**
+	 * @exit: Release callback function
+	 */
+	void (*exit) (struct xloop_file_fmt *xlo_fmt);
+
+	/**
+	 * @read: Read IO callback function
+	 */
+	int (*read) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @write: Write IO callback function
+	 */
+	int (*write) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @read_aio: Asynchronous read IO callback function
+	 */
+	int (*read_aio) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @write_aio: Asynchronous write IO callback function
+	 */
+	int (*write_aio) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @zero: Zero (discard) IO callback function
+	 */
+	int (*write_zeros) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @discard: Discard IO callback function
+	 */
+	int (*discard) (struct xloop_file_fmt *xlo_fmt,
+			struct request *rq);
+
+	/**
+	 * @flush: Flush callback function
+	 */
+	int (*flush) (struct xloop_file_fmt *xlo_fmt);
+
+	/**
+	 * @sector_size: Get sector size callback function
+	 */
+	loff_t (*sector_size) (struct xloop_file_fmt *xlo_fmt,
+				struct file *file, loff_t offset, loff_t sizelimit);
+};
+
+/**
+ * struct xloop_file_fmt_driver - File format subsystem driver
+ *
+ * Data structure to implement file format drivers for the file format
+ * subsystem.
+ */
+struct xloop_file_fmt_driver {
+	/**
+	 * @name: Name of the file format driver
+	 */
+	const char *name;
+
+	/**
+	 * @file_fmt_type: xloop file format type of the file format driver
+	 */
+	const u32 file_fmt_type;
+
+	/**
+	 * @ops: Driver's implemented file format operations
+	 */
+	struct xloop_file_fmt_ops *ops;
+
+	/**
+	 * @ops: Owner of the file format driver
+	 */
+	struct module *owner;
+};
+
+/*
+ * states of the file format
+ *
+ * transitions:
+ *                    xloop_file_fmt_init(...)
+ * ---> uninitialized ------------------------------> initialized
+ *                    xloop_file_fmt_exit(...)
+ *      initialized   ------------------------------> uninitialized
+ *                    xloop_file_fmt_read(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_read_aio(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_write(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_write_aio(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_discard(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_flush(...)
+ *      initialized   ------------------------------> initialized
+ *                    xloop_file_fmt_sector_size(...)
+ *      initialized   ------------------------------> initialized
+ *
+ *                    xloop_file_fmt_change(...)
+ *    +-----------------------------------------------------------+
+ *    |               exit(...)              init(...)            |
+ *    | initialized   -------> uninitialized -------> initialized |
+ *    +-----------------------------------------------------------+
+ */
+enum {
+	file_fmt_uninitialized = 0,
+	file_fmt_initialized
+};
+
+/**
+ * struct xloop_file_fmt - xloop file format
+ *
+ * Data structure to use with the file format the xloop file format subsystem.
+ */
+struct xloop_file_fmt {
+	/**
+	 * @file_fmt_type: Current type of the xloop file format
+	 */
+	u32 file_fmt_type;
+
+	/**
+	 * @file_fmt_state: Current state of the xloop file format
+	 */
+	int file_fmt_state;
+
+	/**
+	 * @xlo: Link to a file format's xloop device
+	 */
+	struct xloop_device *xlo;
+
+	/**
+	 * @private_data: Optional link to a file format's driver specific data
+	 */
+	void *private_data;
+};
+
+
+/* subsystem functions for the driver implementation */
+
+/**
+ * xloop_file_fmt_register_driver - Register a xloop file format driver
+ * @drv: File format driver
+ *
+ * Registers the specified xloop file format driver @drv by the xloop file format
+ * subsystem.
+ */
+extern int xloop_file_fmt_register_driver(struct xloop_file_fmt_driver *drv);
+
+/**
+ * xloop_file_fmt_unregister_driver - Unregister a xloop file format driver
+ * @drv: File format driver
+ *
+ * Unregisters the specified xloop file format driver @drv from the xloop file
+ * format subsystem.
+ */
+extern void xloop_file_fmt_unregister_driver(struct xloop_file_fmt_driver *drv);
+
+
+/* subsystem functions for subsystem usage */
+
+/**
+ * xloop_file_fmt_alloc - Allocate a xloop file format
+ *
+ * Dynamically allocates a xloop file format and returns a pointer to the
+ * created xloop file format.
+ */
+extern struct xloop_file_fmt *xloop_file_fmt_alloc(void);
+
+/**
+ * xloop_file_fmt_free - Free an allocated xloop file format
+ * @xlo_fmt: xloop file format
+ *
+ * Frees the already allocated xloop file format @xlo_fmt.
+ */
+extern void xloop_file_fmt_free(struct xloop_file_fmt *xlo_fmt);
+
+/**
+ * xloop_file_fmt_set_xlo - Set the xloop file format's xloop device
+ * @xlo_fmt: xloop file format
+ * @xlo: xloop device
+ *
+ * The link to the xloop device @xlo is set in the xloop file format @xlo_fmt.
+ */
+extern int xloop_file_fmt_set_xlo(struct xloop_file_fmt *xlo_fmt,
+				struct xloop_device *xlo);
+
+/**
+ * xloop_file_fmt_get_xlo - Get the xloop file format's xloop device
+ * @xlo_fmt: xloop file format
+ *
+ * Returns a pointer to the xloop device of the xloop file format @xlo_fmt.
+ */
+extern struct xloop_device *xloop_file_fmt_get_xlo(struct xloop_file_fmt *xlo_fmt);
+
+/**
+ * xloop_file_fmt_to_dev - Get the xloop file format's disk device
+ * @xlo_fmt: xloop file format
+ *
+ * Returns a pointer to the disk device of the xloop file format's xloop device.
+ */
+extern inline struct device *xloop_file_fmt_to_dev(struct xloop_file_fmt *xlo_fmt);
+
+/**
+ * xloop_file_fmt_init - Initialize a xloop file format
+ * @xlo_fmt: xloop file format
+ * @file_fmt_type: Type of the file format
+ *
+ * Initializes the specified xloop file format @xlo_fmt and sets up the correct
+ * file format type @file_fmt_type. Depending on @file_fmt_type, the correct
+ * xloop file format driver is loaded in the subsystems backend. If no xloop file
+ * format driver for the specified file format is available an error is
+ * returned.
+ */
+extern int xloop_file_fmt_init(struct xloop_file_fmt *xlo_fmt,
+			      u32 file_fmt_type);
+
+/**
+ * xloop_file_fmt_exit - Release a xloop file format
+ * @xlo_fmt: xloop file format
+ *
+ * Releases the specified xloop file format @xlo_fmt and all its resources.
+ */
+extern void xloop_file_fmt_exit(struct xloop_file_fmt *xlo_fmt);
+
+/**
+ * xloop_file_fmt_read - Read IO from a xloop file format
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Reads IO from the file format's xloop device by sending the IO read request
+ * @rq to the xloop file format subsystem. The subsystem calls the registered
+ * callback function of the suitable xloop file format driver.
+ */
+extern int xloop_file_fmt_read(struct xloop_file_fmt *xlo_fmt,
+			      struct request *rq);
+
+/**
+ * xloop_file_fmt_read_aio - Read IO from a xloop file format asynchronously
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Reads IO from the file format's xloop device asynchronously by sending the
+ * IO read aio request @rq to the xloop file format subsystem. The subsystem
+ * calls the registered callback function of the suitable xloop file format
+ * driver.
+ */
+extern int xloop_file_fmt_read_aio(struct xloop_file_fmt *xlo_fmt,
+				  struct request *rq);
+
+/**
+ * xloop_file_fmt_write - Write IO to a xloop file format
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Write IO to the file format's xloop device by sending the IO write request
+ * @rq to the xloop file format subsystem. The subsystem calls the registered
+ * callback function of the suitable xloop file format driver.
+ */
+extern int xloop_file_fmt_write(struct xloop_file_fmt *xlo_fmt,
+			       struct request *rq);
+
+/**
+ * xloop_file_fmt_write_aio - Write IO to a xloop file format asynchronously
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Write IO to the file format's xloop device asynchronously by sending the
+ * IO write aio request @rq to the xloop file format subsystem. The subsystem
+ * calls the registered callback function of the suitable xloop file format
+ * driver.
+ */
+extern int xloop_file_fmt_write_aio(struct xloop_file_fmt *xlo_fmt,
+				   struct request *rq);
+
+/**
+ * xloop_file_fmt_write_zeros - Zero (discard) IO on a xloop file format
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Zero (discard) IO on the file format's xloop device by sending the IO write
+ * zeros request @rq to the xloop file format subsystem. The subsystem calls the
+ * registered callback function of the suitable xloop file format driver.
+ */
+extern int xloop_file_fmt_write_zeros(struct xloop_file_fmt *xlo_fmt,
+				 struct request *rq);
+
+/**
+ * xloop_file_fmt_discard - Discard IO on a xloop file format
+ * @xlo_fmt: xloop file format
+ * @rq: IO Request
+ *
+ * Discard IO on the file format's xloop device by sending the IO discard
+ * request @rq to the xloop file format subsystem. The subsystem calls the
+ * registered callback function of the suitable xloop file format driver.
+ */
+extern int xloop_file_fmt_discard(struct xloop_file_fmt *xlo_fmt,
+				 struct request *rq);
+
+/**
+ * xloop_file_fmt_flush - Flush a xloop file format
+ * @xlo_fmt: xloop file format
+ *
+ * Flush the file format's xloop device by calling the registered callback
+ * function of the suitable xloop file format driver.
+ */
+extern int xloop_file_fmt_flush(struct xloop_file_fmt *xlo_fmt);
+
+/**
+ * xloop_file_fmt_sector_size - Get sector size of a xloop file format
+ * @xlo_fmt: xloop file format
+ * @file: xloop file formats file for sector size calculation
+ * @offset: Offset within the file for sector size calculation
+ * @sizelimit: Sizelimit of the file for sector size calculation
+ *
+ * Returns the physical sector size of the given xloop file format's file.
+ * If the xloop file format implements a sparse disk image format, then this
+ * function returns the virtual sector size.
+ */
+extern loff_t xloop_file_fmt_sector_size(struct xloop_file_fmt *xlo_fmt,
+				struct file *file, loff_t offset, loff_t sizelimit);
+
+/**
+ * xloop_file_fmt_change - Change the xloop file format's type
+ * @xlo_fmt: xloop file format
+ * @file_fmt_type_new: xloop file format type
+ *
+ * Changes the file format type of the already initialized xloop file format
+ * @xlo_fmt. Therefore, the function releases the old file format and frees all
+ * of its resources before the xloop file format @xlo_fmt is initialized and set
+ * up with the new file format @file_fmt_type_new.
+ */
+extern int xloop_file_fmt_change(struct xloop_file_fmt *xlo_fmt,
+				u32 file_fmt_type_new);
+
+
+/* helper functions of the subsystem */
+
+/**
+ * xloop_file_fmt_print_type - Convert file format type to string
+ * @file_fmt_type: xloop file format type
+ * @file_fmt_name: xloop file format type string
+ *
+ * Converts the specified numeric @file_fmt_type value into a human readable
+ * string stating the file format as string in @file_fmt_name.
+ */
+extern ssize_t xloop_file_fmt_print_type(u32 file_fmt_type,
+					char *file_fmt_name);
+
+#endif