md.h

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

/*
   md.h : Multiple Devices driver for Linux
          Copyright (C) 1994-96 Marc ZYNGIER
	  <[e-mail]> or
	  <[e-mail]>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   You should have received a copy of the GNU General Public License
   (for example /usr/src/linux/COPYING); if not, write to the Free
   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#ifndef _MD_H
#define _MD_H

#include <asm/segment.h>
#include <linux/major.h>
#include <linux/ioctl.h>
#include <linux/types.h>

/*
 * Different major versions are not compatible.
 * Different minor versions are only downward compatible.
 * Different patchlevel versions are downward and upward compatible.
 */
#define MD_MAJOR_VERSION		0
#define MD_MINOR_VERSION		36
#define MD_PATCHLEVEL_VERSION		3

/* ioctls */
#define REGISTER_DEV _IO (MD_MAJOR, 1)
#define START_MD     _IO (MD_MAJOR, 2)
#define STOP_MD      _IO (MD_MAJOR, 3)

/*
   personalities :
   Byte 0 : Chunk size factor
   Byte 1 : Fault tolerance count for each physical device
            (   0 means no fault tolerance,
             0xFF means always tolerate faults), not used by now.
   Byte 2 : Personality
   Byte 3 : Reserved.
 */

#define FAULT_SHIFT       8
#define PERSONALITY_SHIFT 16

#define FACTOR_MASK       0x000000FFUL
#define FAULT_MASK        0x0000FF00UL
#define PERSONALITY_MASK  0x00FF0000UL

#define MD_RESERVED       0	/* Not used by now */
#define LINEAR            (1UL << PERSONALITY_SHIFT)
#define STRIPED           (2UL << PERSONALITY_SHIFT)
#define RAID0             STRIPED
#define RAID1             (3UL << PERSONALITY_SHIFT)
#define RAID5             (4UL << PERSONALITY_SHIFT)
#define MAX_PERSONALITY   5

/*
 * MD superblock.
 *
 * The MD superblock maintains some statistics on each MD configuration.
 * Each real device in the MD set contains it near the end of the device.
 * Some of the ideas are copied from the ext2fs implementation.
 *
 * We currently use 4096 bytes as follows:
 *
 *	word offset	function
 *
 *	   0  -    31	Constant generic MD device information.
 *        32  -    63   Generic state information.
 *	  64  -   127	Personality specific information.
 *	 128  -   511	12 32-words descriptors of the disks in the raid set.
 *	 512  -   911	Reserved.
 *	 912  -  1023	Disk specific descriptor.
 */

/*
 * If x is the real device size in bytes, we return an apparent size of:
 *
 *	y = (x & ~(MD_RESERVED_BYTES - 1)) - MD_RESERVED_BYTES
 *
 * and place the 4kB superblock at offset y.
 */
#define MD_RESERVED_BYTES		(64 * 1024)
#define MD_RESERVED_SECTORS		(MD_RESERVED_BYTES / 512)
#define MD_RESERVED_BLOCKS		(MD_RESERVED_BYTES / BLOCK_SIZE)

#define MD_NEW_SIZE_SECTORS(x)		((x & ~(MD_RESERVED_SECTORS - 1)) - MD_RESERVED_SECTORS)
#define MD_NEW_SIZE_BLOCKS(x)		((x & ~(MD_RESERVED_BLOCKS - 1)) - MD_RESERVED_BLOCKS)

#define MD_SB_BYTES			4096
#define MD_SB_WORDS			(MD_SB_BYTES / 4)
#define MD_SB_BLOCKS			(MD_SB_BYTES / BLOCK_SIZE)
#define MD_SB_SECTORS			(MD_SB_BYTES / 512)

/*
 * The following are counted in 32-bit words
 */
#define	MD_SB_GENERIC_OFFSET		0
#define MD_SB_PERSONALITY_OFFSET	64
#define MD_SB_DISKS_OFFSET		128
#define MD_SB_DESCRIPTOR_OFFSET		992

#define MD_SB_GENERIC_CONSTANT_WORDS	32
#define MD_SB_GENERIC_STATE_WORDS	32
#define MD_SB_GENERIC_WORDS		(MD_SB_GENERIC_CONSTANT_WORDS + MD_SB_GENERIC_STATE_WORDS)
#define MD_SB_PERSONALITY_WORDS		64
#define MD_SB_DISKS_WORDS		384
#define MD_SB_DESCRIPTOR_WORDS		32
#define MD_SB_RESERVED_WORDS		(1024 - MD_SB_GENERIC_WORDS - MD_SB_PERSONALITY_WORDS - MD_SB_DISKS_WORDS - MD_SB_DESCRIPTOR_WORDS)
#define MD_SB_EQUAL_WORDS		(MD_SB_GENERIC_WORDS + MD_SB_PERSONALITY_WORDS + MD_SB_DISKS_WORDS)
#define MD_SB_DISKS			(MD_SB_DISKS_WORDS / MD_SB_DESCRIPTOR_WORDS)

/*
 * Device "operational" state bits
 */
#define MD_FAULTY_DEVICE		0	/* Device is faulty / operational */
#define MD_ACTIVE_DEVICE		1	/* Device is a part or the raid set / spare disk */
#define MD_SYNC_DEVICE			2	/* Device is in sync with the raid set */

typedef struct md_device_descriptor_s {
	__u32 number;		/* 0 Device number in the entire set */
	__u32 major;		/* 1 Device major number */
	__u32 minor;		/* 2 Device minor number */
	__u32 raid_disk;	/* 3 The role of the device in the raid set */
	__u32 state;		/* 4 Operational state */
	__u32 reserved[MD_SB_DESCRIPTOR_WORDS - 5];
} md_descriptor_t;

#define MD_SB_MAGIC		0xa92b4efc

/*
 * Superblock state bits
 */
#define MD_SB_CLEAN		0
#define MD_SB_ERRORS		1

typedef struct md_superblock_s {

	/*
	 * Constant generic information
	 */
	__u32 md_magic;		/*  0 MD identifier */
	__u32 major_version;	/*  1 major version to which the set conforms */
	__u32 minor_version;	/*  2 minor version to which the set conforms */
	__u32 patch_version;	/*  3 patchlevel version to which the set conforms */
	__u32 gvalid_words;	/*  4 Number of non-reserved words in this section */
	__u32 set_magic;	/*  5 Raid set identifier */
	__u32 ctime;		/*  6 Creation time */
	__u32 level;		/*  7 Raid personality (mirroring, raid5, ...) */
	__u32 size;		/*  8 Apparent size of each individual disk, in kB */
	__u32 nr_disks;		/*  9 Number of total disks in the raid set */
	__u32 raid_disks;	/* 10 Number of disks in a fully functional raid set */
	__u32 gstate_creserved[MD_SB_GENERIC_CONSTANT_WORDS - 11];

	/*
	 * Generic state information
	 */
	__u32 utime;		/*  0 Superblock update time */
	__u32 state;		/*  1 State bits (clean, ...) */
	__u32 active_disks;	/*  2 Number of currently active disks (some non-faulty disks might not be in sync) */
	__u32 working_disks;	/*  3 Number of working disks */
	__u32 failed_disks;	/*  4 Number of failed disks */
	__u32 spare_disks;	/*  5 Number of spare disks */
	__u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 6];

	/*
	 * Personality information
	 */
	__u32 parity_algorithm;
	__u32 chunk_size;
	__u32 pstate_reserved[MD_SB_PERSONALITY_WORDS - 2];

	/*
	 * Disks information
	 */
	md_descriptor_t disks[MD_SB_DISKS];

	/*
	 * Reserved
	 */
	__u32 reserved[MD_SB_RESERVED_WORDS];

	/*
	 * Active descriptor
	 */
	md_descriptor_t descriptor;
} md_superblock_t;

#ifdef __KERNEL__

#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/blkdev.h>

#define MAX_REAL     8		/* Max number of physical dev per md dev */
#define MAX_MD_DEV   4		/* Max number of md dev */
#define MAX_MD_THREADS 2	/* Max number of kernel threads */

#define FACTOR(a)         ((a)->repartition & FACTOR_MASK)
#define MAX_FAULT(a)      (((a)->repartition & FAULT_MASK)>>8)
#define PERSONALITY(a)    ((a)->repartition & PERSONALITY_MASK)

#define FACTOR_SHIFT(a) (PAGE_SHIFT + (a) - 10)

struct real_dev
{
  kdev_t dev;			/* Device number */
  int size;			/* Device size (in blocks) */
  int offset;			/* Real device offset (in blocks) in md dev
				   (only used in linear mode) */
  struct inode *inode;		/* Lock inode */
  md_superblock_t *sb;
  u32 sb_offset;
};

struct md_dev;

struct md_personality
{
  char *name;
  int (*map)(struct md_dev *md_dev, kdev_t *rdev,
	              unsigned long *rsector, unsigned long size);
  int (*make_request)(struct md_dev *md_dev, int rw, struct buffer_head * bh);
  void (*end_request)(struct buffer_head * bh, int uptodate);
  int (*run)(int minor, struct md_dev *md_dev);
  int (*stop)(int minor, struct md_dev *md_dev);
  int (*status)(char *page, int minor, struct md_dev *md_dev);
  int (*ioctl)(struct inode *inode, struct file *file,
	       unsigned int cmd, unsigned long arg);
  int max_invalid_dev;
  int (*error_handler)(struct md_dev *md_dev, kdev_t dev);
};

struct md_dev
{
  struct real_dev devices[MAX_REAL];
  struct md_personality *pers;
  md_superblock_t *sb;
  int sb_dirty;
  int repartition;
  int busy;
  int nb_dev;
  void *private;
};

struct md_thread {
	void			(*run) (void *data);
	void			*data;
	struct wait_queue	*wqueue;
	__u32			flags;
};

#define THREAD_WAKEUP	0

extern struct md_dev md_dev[MAX_MD_DEV];
extern int md_size[MAX_MD_DEV];

extern char *partition_name (kdev_t dev);

extern int register_md_personality (int p_num, struct md_personality *p);
extern int unregister_md_personality (int p_num);
extern struct md_thread *md_register_thread (void (*run) (void *data), void *data);
extern void md_unregister_thread (struct md_thread *thread);
extern void md_wakeup_thread(struct md_thread *thread);
extern int md_update_sb (int minor);

#endif /* __KERNEL__ */
#endif /* _MD_H */