File: /usr/src/linux/include/linux/raid/md_p.h
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 typedef struct mdp_device_descriptor_s {
83 __u32 number; /* 0 Device number in the entire set */
84 __u32 major; /* 1 Device major number */
85 __u32 minor; /* 2 Device minor number */
86 __u32 raid_disk; /* 3 The role of the device in the raid set */
87 __u32 state; /* 4 Operational state */
88 __u32 reserved[MD_SB_DESCRIPTOR_WORDS - 5];
89 } mdp_disk_t;
90
91 #define MD_SB_MAGIC 0xa92b4efc
92
93 /*
94 * Superblock state bits
95 */
96 #define MD_SB_CLEAN 0
97 #define MD_SB_ERRORS 1
98
99 typedef struct mdp_superblock_s {
100 /*
101 * Constant generic information
102 */
103 __u32 md_magic; /* 0 MD identifier */
104 __u32 major_version; /* 1 major version to which the set conforms */
105 __u32 minor_version; /* 2 minor version ... */
106 __u32 patch_version; /* 3 patchlevel version ... */
107 __u32 gvalid_words; /* 4 Number of used words in this section */
108 __u32 set_uuid0; /* 5 Raid set identifier */
109 __u32 ctime; /* 6 Creation time */
110 __u32 level; /* 7 Raid personality */
111 __u32 size; /* 8 Apparent size of each individual disk */
112 __u32 nr_disks; /* 9 total disks in the raid set */
113 __u32 raid_disks; /* 10 disks in a fully functional raid set */
114 __u32 md_minor; /* 11 preferred MD minor device number */
115 __u32 not_persistent; /* 12 does it have a persistent superblock */
116 __u32 set_uuid1; /* 13 Raid set identifier #2 */
117 __u32 set_uuid2; /* 14 Raid set identifier #3 */
118 __u32 set_uuid3; /* 15 Raid set identifier #4 */
119 __u32 gstate_creserved[MD_SB_GENERIC_CONSTANT_WORDS - 16];
120
121 /*
122 * Generic state information
123 */
124 __u32 utime; /* 0 Superblock update time */
125 __u32 state; /* 1 State bits (clean, ...) */
126 __u32 active_disks; /* 2 Number of currently active disks */
127 __u32 working_disks; /* 3 Number of working disks */
128 __u32 failed_disks; /* 4 Number of failed disks */
129 __u32 spare_disks; /* 5 Number of spare disks */
130 __u32 sb_csum; /* 6 checksum of the whole superblock */
131 #ifdef __BIG_ENDIAN
132 __u32 events_hi; /* 7 high-order of superblock update count */
133 __u32 events_lo; /* 8 low-order of superblock update count */
134 #else
135 __u32 events_lo; /* 7 low-order of superblock update count */
136 __u32 events_hi; /* 8 high-order of superblock update count */
137 #endif
138 __u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 9];
139
140 /*
141 * Personality information
142 */
143 __u32 layout; /* 0 the array's physical layout */
144 __u32 chunk_size; /* 1 chunk size in bytes */
145 __u32 root_pv; /* 2 LV root PV */
146 __u32 root_block; /* 3 LV root block */
147 __u32 pstate_reserved[MD_SB_PERSONALITY_WORDS - 4];
148
149 /*
150 * Disks information
151 */
152 mdp_disk_t disks[MD_SB_DISKS];
153
154 /*
155 * Reserved
156 */
157 __u32 reserved[MD_SB_RESERVED_WORDS];
158
159 /*
160 * Active descriptor
161 */
162 mdp_disk_t this_disk;
163
164 } mdp_super_t;
165
166 static inline __u64 md_event(mdp_super_t *sb) {
167 __u64 ev = sb->events_hi;
168 return (ev<<32)| sb->events_lo;
169 }
170
171 #endif
172
173