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      1 /*
      2    md_p.h : physical layout of Linux RAID devices
      3           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
      4 
      5    This program is free software; you can redistribute it and/or modify
      6    it under the terms of the GNU General Public License as published by
      7    the Free Software Foundation; either version 2, or (at your option)
      8    any later version.
      9 
     10    You should have received a copy of the GNU General Public License
     11    (for example /usr/src/linux/COPYING); if not, write to the Free
     12    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
     13 */
     14 
     15 #ifndef _MD_P_H
     16 #define _MD_P_H
     17 
     18 /*
     19  * RAID superblock.
     20  *
     21  * The RAID superblock maintains some statistics on each RAID configuration.
     22  * Each real device in the RAID set contains it near the end of the device.
     23  * Some of the ideas are copied from the ext2fs implementation.
     24  *
     25  * We currently use 4096 bytes as follows:
     26  *
     27  *	word offset	function
     28  *
     29  *	   0  -    31	Constant generic RAID device information.
     30  *        32  -    63   Generic state information.
     31  *	  64  -   127	Personality specific information.
     32  *	 128  -   511	12 32-words descriptors of the disks in the raid set.
     33  *	 512  -   911	Reserved.
     34  *	 912  -  1023	Disk specific descriptor.
     35  */
     36 
     37 /*
     38  * If x is the real device size in bytes, we return an apparent size of:
     39  *
     40  *	y = (x & ~(MD_RESERVED_BYTES - 1)) - MD_RESERVED_BYTES
     41  *
     42  * and place the 4kB superblock at offset y.
     43  */
     44 #define MD_RESERVED_BYTES		(64 * 1024)
     45 #define MD_RESERVED_SECTORS		(MD_RESERVED_BYTES / 512)
     46 #define MD_RESERVED_BLOCKS		(MD_RESERVED_BYTES / BLOCK_SIZE)
     47 
     48 #define MD_NEW_SIZE_SECTORS(x)		((x & ~(MD_RESERVED_SECTORS - 1)) - MD_RESERVED_SECTORS)
     49 #define MD_NEW_SIZE_BLOCKS(x)		((x & ~(MD_RESERVED_BLOCKS - 1)) - MD_RESERVED_BLOCKS)
     50 
     51 #define MD_SB_BYTES			4096
     52 #define MD_SB_WORDS			(MD_SB_BYTES / 4)
     53 #define MD_SB_BLOCKS			(MD_SB_BYTES / BLOCK_SIZE)
     54 #define MD_SB_SECTORS			(MD_SB_BYTES / 512)
     55 
     56 /*
     57  * The following are counted in 32-bit words
     58  */
     59 #define	MD_SB_GENERIC_OFFSET		0
     60 #define MD_SB_PERSONALITY_OFFSET	64
     61 #define MD_SB_DISKS_OFFSET		128
     62 #define MD_SB_DESCRIPTOR_OFFSET		992
     63 
     64 #define MD_SB_GENERIC_CONSTANT_WORDS	32
     65 #define MD_SB_GENERIC_STATE_WORDS	32
     66 #define MD_SB_GENERIC_WORDS		(MD_SB_GENERIC_CONSTANT_WORDS + MD_SB_GENERIC_STATE_WORDS)
     67 #define MD_SB_PERSONALITY_WORDS		64
     68 #define MD_SB_DESCRIPTOR_WORDS		32
     69 #define MD_SB_DISKS			27
     70 #define MD_SB_DISKS_WORDS		(MD_SB_DISKS*MD_SB_DESCRIPTOR_WORDS)
     71 #define MD_SB_RESERVED_WORDS		(1024 - MD_SB_GENERIC_WORDS - MD_SB_PERSONALITY_WORDS - MD_SB_DISKS_WORDS - MD_SB_DESCRIPTOR_WORDS)
     72 #define MD_SB_EQUAL_WORDS		(MD_SB_GENERIC_WORDS + MD_SB_PERSONALITY_WORDS + MD_SB_DISKS_WORDS)
     73 
     74 /*
     75  * Device "operational" state bits
     76  */
     77 #define MD_DISK_FAULTY		0 /* disk is faulty / operational */
     78 #define MD_DISK_ACTIVE		1 /* disk is running or spare disk */
     79 #define MD_DISK_SYNC		2 /* disk is in sync with the raid set */
     80 #define MD_DISK_REMOVED		3 /* disk is in sync with the raid set */
     81 
     82 #define	MD_DISK_WRITEMOSTLY	9 /* disk is "write-mostly" is RAID1 config.
     83 				   * read requests will only be sent here in
     84 				   * dire need
     85 				   */
     86 
     87 typedef struct mdp_device_descriptor_s {
     88 	__u32 number;		/* 0 Device number in the entire set	      */
     89 	__u32 major;		/* 1 Device major number		      */
     90 	__u32 minor;		/* 2 Device minor number		      */
     91 	__u32 raid_disk;	/* 3 The role of the device in the raid set   */
     92 	__u32 state;		/* 4 Operational state			      */
     93 	__u32 reserved[MD_SB_DESCRIPTOR_WORDS - 5];
     94 } mdp_disk_t;
     95 
     96 #define MD_SB_MAGIC		0xa92b4efc
     97 
     98 /*
     99  * Superblock state bits
    100  */
    101 #define MD_SB_CLEAN		0
    102 #define MD_SB_ERRORS		1
    103 
    104 #define	MD_SB_BITMAP_PRESENT	8 /* bitmap may be present nearby */
    105 
    106 /*
    107  * Notes:
    108  * - if an array is being reshaped (restriped) in order to change the
    109  *   the number of active devices in the array, 'raid_disks' will be
    110  *   the larger of the old and new numbers.  'delta_disks' will
    111  *   be the "new - old".  So if +ve, raid_disks is the new value, and
    112  *   "raid_disks-delta_disks" is the old.  If -ve, raid_disks is the
    113  *   old value and "raid_disks+delta_disks" is the new (smaller) value.
    114  */
    115 
    116 
    117 typedef struct mdp_superblock_s {
    118 	/*
    119 	 * Constant generic information
    120 	 */
    121 	__u32 md_magic;		/*  0 MD identifier 			      */
    122 	__u32 major_version;	/*  1 major version to which the set conforms */
    123 	__u32 minor_version;	/*  2 minor version ...			      */
    124 	__u32 patch_version;	/*  3 patchlevel version ...		      */
    125 	__u32 gvalid_words;	/*  4 Number of used words in this section    */
    126 	__u32 set_uuid0;	/*  5 Raid set identifier		      */
    127 	__u32 ctime;		/*  6 Creation time			      */
    128 	__u32 level;		/*  7 Raid personality			      */
    129 	__u32 size;		/*  8 Apparent size of each individual disk   */
    130 	__u32 nr_disks;		/*  9 total disks in the raid set	      */
    131 	__u32 raid_disks;	/* 10 disks in a fully functional raid set    */
    132 	__u32 md_minor;		/* 11 preferred MD minor device number	      */
    133 	__u32 not_persistent;	/* 12 does it have a persistent superblock    */
    134 	__u32 set_uuid1;	/* 13 Raid set identifier #2		      */
    135 	__u32 set_uuid2;	/* 14 Raid set identifier #3		      */
    136 	__u32 set_uuid3;	/* 15 Raid set identifier #4		      */
    137 	__u32 gstate_creserved[MD_SB_GENERIC_CONSTANT_WORDS - 16];
    138 
    139 	/*
    140 	 * Generic state information
    141 	 */
    142 	__u32 utime;		/*  0 Superblock update time		      */
    143 	__u32 state;		/*  1 State bits (clean, ...)		      */
    144 	__u32 active_disks;	/*  2 Number of currently active disks	      */
    145 	__u32 working_disks;	/*  3 Number of working disks		      */
    146 	__u32 failed_disks;	/*  4 Number of failed disks		      */
    147 	__u32 spare_disks;	/*  5 Number of spare disks		      */
    148 	__u32 sb_csum;		/*  6 checksum of the whole superblock        */
    149 #ifdef __BIG_ENDIAN
    150 	__u32 events_hi;	/*  7 high-order of superblock update count   */
    151 	__u32 events_lo;	/*  8 low-order of superblock update count    */
    152 	__u32 cp_events_hi;	/*  9 high-order of checkpoint update count   */
    153 	__u32 cp_events_lo;	/* 10 low-order of checkpoint update count    */
    154 #else
    155 	__u32 events_lo;	/*  7 low-order of superblock update count    */
    156 	__u32 events_hi;	/*  8 high-order of superblock update count   */
    157 	__u32 cp_events_lo;	/*  9 low-order of checkpoint update count    */
    158 	__u32 cp_events_hi;	/* 10 high-order of checkpoint update count   */
    159 #endif
    160 	__u32 recovery_cp;	/* 11 recovery checkpoint sector count	      */
    161 	/* There are only valid for minor_version > 90 */
    162 	__u64 reshape_position;	/* 12,13 next address in array-space for reshape */
    163 	__u32 new_level;	/* 14 new level we are reshaping to	      */
    164 	__u32 delta_disks;	/* 15 change in number of raid_disks	      */
    165 	__u32 new_layout;	/* 16 new layout			      */
    166 	__u32 new_chunk;	/* 17 new chunk size (bytes)		      */
    167 	__u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 18];
    168 
    169 	/*
    170 	 * Personality information
    171 	 */
    172 	__u32 layout;		/*  0 the array's physical layout	      */
    173 	__u32 chunk_size;	/*  1 chunk size in bytes		      */
    174 	__u32 root_pv;		/*  2 LV root PV */
    175 	__u32 root_block;	/*  3 LV root block */
    176 	__u32 pstate_reserved[MD_SB_PERSONALITY_WORDS - 4];
    177 
    178 	/*
    179 	 * Disks information
    180 	 */
    181 	mdp_disk_t disks[MD_SB_DISKS];
    182 
    183 	/*
    184 	 * Reserved
    185 	 */
    186 	__u32 reserved[MD_SB_RESERVED_WORDS];
    187 
    188 	/*
    189 	 * Active descriptor
    190 	 */
    191 	mdp_disk_t this_disk;
    192 
    193 } mdp_super_t;
    194 
    195 static inline __u64 md_event(mdp_super_t *sb) {
    196 	__u64 ev = sb->events_hi;
    197 	return (ev<<32)| sb->events_lo;
    198 }
    199 
    200 /*
    201  * The version-1 superblock :
    202  * All numeric fields are little-endian.
    203  *
    204  * total size: 256 bytes plus 2 per device.
    205  *  1K allows 384 devices.
    206  */
    207 struct mdp_superblock_1 {
    208 	/* constant array information - 128 bytes */
    209 	__u32	magic;		/* MD_SB_MAGIC: 0xa92b4efc - little endian */
    210 	__u32	major_version;	/* 1 */
    211 	__u32	feature_map;	/* bit 0 set if 'bitmap_offset' is meaningful */
    212 	__u32	pad0;		/* always set to 0 when writing */
    213 
    214 	__u8	set_uuid[16];	/* user-space generated. */
    215 	char	set_name[32];	/* set and interpreted by user-space */
    216 
    217 	__u64	ctime;		/* lo 40 bits are seconds, top 24 are microseconds or 0*/
    218 	__u32	level;		/* -4 (multipath), -1 (linear), 0,1,4,5 */
    219 	__u32	layout;		/* only for raid5 and raid10 currently */
    220 	__u64	size;		/* used size of component devices, in 512byte sectors */
    221 
    222 	__u32	chunksize;	/* in 512byte sectors */
    223 	__u32	raid_disks;
    224 	__u32	bitmap_offset;	/* sectors after start of superblock that bitmap starts
    225 				 * NOTE: signed, so bitmap can be before superblock
    226 				 * only meaningful of feature_map[0] is set.
    227 				 */
    228 
    229 	/* These are only valid with feature bit '4' */
    230 	__u32	new_level;	/* new level we are reshaping to		*/
    231 	__u64	reshape_position;	/* next address in array-space for reshape */
    232 	__u32	delta_disks;	/* change in number of raid_disks		*/
    233 	__u32	new_layout;	/* new layout					*/
    234 	__u32	new_chunk;	/* new chunk size (bytes)			*/
    235 	__u8	pad1[128-124];	/* set to 0 when written */
    236 
    237 	/* constant this-device information - 64 bytes */
    238 	__u64	data_offset;	/* sector start of data, often 0 */
    239 	__u64	data_size;	/* sectors in this device that can be used for data */
    240 	__u64	super_offset;	/* sector start of this superblock */
    241 	__u64	recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
    242 	__u32	dev_number;	/* permanent identifier of this  device - not role in raid */
    243 	__u32	cnt_corrected_read; /* number of read errors that were corrected by re-writing */
    244 	__u8	device_uuid[16]; /* user-space setable, ignored by kernel */
    245 	__u8	devflags;	/* per-device flags.  Only one defined...*/
    246 #define	WriteMostly1	1	/* mask for writemostly flag in above */
    247 	__u8	pad2[64-57];	/* set to 0 when writing */
    248 
    249 	/* array state information - 64 bytes */
    250 	__u64	utime;		/* 40 bits second, 24 btes microseconds */
    251 	__u64	events;		/* incremented when superblock updated */
    252 	__u64	resync_offset;	/* data before this offset (from data_offset) known to be in sync */
    253 	__u32	sb_csum;	/* checksum upto devs[max_dev] */
    254 	__u32	max_dev;	/* size of devs[] array to consider */
    255 	__u8	pad3[64-32];	/* set to 0 when writing */
    256 
    257 	/* device state information. Indexed by dev_number.
    258 	 * 2 bytes per device
    259 	 * Note there are no per-device state flags. State information is rolled
    260 	 * into the 'roles' value.  If a device is spare or faulty, then it doesn't
    261 	 * have a meaningful role.
    262 	 */
    263 	__u16	dev_roles[0];	/* role in array, or 0xffff for a spare, or 0xfffe for faulty */
    264 };
    265 
    266 /* feature_map bits */
    267 #define MD_FEATURE_BITMAP_OFFSET	1
    268 #define	MD_FEATURE_RECOVERY_OFFSET	2 /* recovery_offset is present and
    269 					   * must be honoured
    270 					   */
    271 #define	MD_FEATURE_RESHAPE_ACTIVE	4
    272 
    273 #define	MD_FEATURE_ALL			(1|2|4)
    274 
    275 #endif
    276 
    277