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001: /*
002:    md_p.h : physical layout of Linux RAID devices
003:           Copyright (C) 1996-98 Ingo Molnar, Gadi Oxman
004:           
005:    This program is free software; you can redistribute it and/or modify
006:    it under the terms of the GNU General Public License as published by
007:    the Free Software Foundation; either version 2, or (at your option)
008:    any later version.
009:    
010:    You should have received a copy of the GNU General Public License
011:    (for example /usr/src/linux/COPYING); if not, write to the Free
012:    Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  
013: */
014: 
015: #ifndef _MD_P_H
016: #define _MD_P_H
017: 
018: #include <linux/types.h>
019: 
020: /*
021:  * RAID superblock.
022:  *
023:  * The RAID superblock maintains some statistics on each RAID configuration.
024:  * Each real device in the RAID set contains it near the end of the device.
025:  * Some of the ideas are copied from the ext2fs implementation.
026:  *
027:  * We currently use 4096 bytes as follows:
028:  *
029:  *      word offset     function
030:  *
031:  *         0  -    31   Constant generic RAID device information.
032:  *        32  -    63   Generic state information.
033:  *        64  -   127   Personality specific information.
034:  *       128  -   511   12 32-words descriptors of the disks in the raid set.
035:  *       512  -   911   Reserved.
036:  *       912  -  1023   Disk specific descriptor.
037:  */
038: 
039: /*
040:  * If x is the real device size in bytes, we return an apparent size of:
041:  *
042:  *      y = (x & ~(MD_RESERVED_BYTES - 1)) - MD_RESERVED_BYTES
043:  *
044:  * and place the 4kB superblock at offset y.
045:  */
046: #define MD_RESERVED_BYTES               (64 * 1024)
047: #define MD_RESERVED_SECTORS             (MD_RESERVED_BYTES / 512)
048: 
049: #define MD_NEW_SIZE_SECTORS(x)          ((x & ~(MD_RESERVED_SECTORS - 1)) - MD_RESERVED_SECTORS)
050: 
051: #define MD_SB_BYTES                     4096
052: #define MD_SB_WORDS                     (MD_SB_BYTES / 4)
053: #define MD_SB_SECTORS                   (MD_SB_BYTES / 512)
054: 
055: /*
056:  * The following are counted in 32-bit words
057:  */
058: #define MD_SB_GENERIC_OFFSET            0
059: #define MD_SB_PERSONALITY_OFFSET        64
060: #define MD_SB_DISKS_OFFSET              128
061: #define MD_SB_DESCRIPTOR_OFFSET         992
062: 
063: #define MD_SB_GENERIC_CONSTANT_WORDS    32
064: #define MD_SB_GENERIC_STATE_WORDS       32
065: #define MD_SB_GENERIC_WORDS             (MD_SB_GENERIC_CONSTANT_WORDS + MD_SB_GENERIC_STATE_WORDS)
066: #define MD_SB_PERSONALITY_WORDS         64
067: #define MD_SB_DESCRIPTOR_WORDS          32
068: #define MD_SB_DISKS                     27
069: #define MD_SB_DISKS_WORDS               (MD_SB_DISKS*MD_SB_DESCRIPTOR_WORDS)
070: #define MD_SB_RESERVED_WORDS            (1024 - MD_SB_GENERIC_WORDS - MD_SB_PERSONALITY_WORDS - MD_SB_DISKS_WORDS - MD_SB_DESCRIPTOR_WORDS)
071: #define MD_SB_EQUAL_WORDS               (MD_SB_GENERIC_WORDS + MD_SB_PERSONALITY_WORDS + MD_SB_DISKS_WORDS)
072: 
073: /*
074:  * Device "operational" state bits
075:  */
076: #define MD_DISK_FAULTY          0 /* disk is faulty / operational */
077: #define MD_DISK_ACTIVE          1 /* disk is running or spare disk */
078: #define MD_DISK_SYNC            2 /* disk is in sync with the raid set */
079: #define MD_DISK_REMOVED         3 /* disk is in sync with the raid set */
080: 
081: #define MD_DISK_WRITEMOSTLY     9 /* disk is "write-mostly" is RAID1 config.
082:                                    * read requests will only be sent here in
083:                                    * dire need
084:                                    */
085: 
086: typedef struct mdp_device_descriptor_s {
087:         __u32 number;           /* 0 Device number in the entire set          */
088:         __u32 major;            /* 1 Device major number                      */
089:         __u32 minor;            /* 2 Device minor number                      */
090:         __u32 raid_disk;        /* 3 The role of the device in the raid set   */
091:         __u32 state;            /* 4 Operational state                        */
092:         __u32 reserved[MD_SB_DESCRIPTOR_WORDS - 5];
093: } mdp_disk_t;
094: 
095: #define MD_SB_MAGIC             0xa92b4efc
096: 
097: /*
098:  * Superblock state bits
099:  */
100: #define MD_SB_CLEAN             0
101: #define MD_SB_ERRORS            1
102: 
103: #define MD_SB_BITMAP_PRESENT    8 /* bitmap may be present nearby */
104: 
105: /*
106:  * Notes:
107:  * - if an array is being reshaped (restriped) in order to change the
108:  *   the number of active devices in the array, 'raid_disks' will be
109:  *   the larger of the old and new numbers.  'delta_disks' will
110:  *   be the "new - old".  So if +ve, raid_disks is the new value, and
111:  *   "raid_disks-delta_disks" is the old.  If -ve, raid_disks is the
112:  *   old value and "raid_disks+delta_disks" is the new (smaller) value.
113:  */
114: 
115: 
116: typedef struct mdp_superblock_s {
117:         /*
118:          * Constant generic information
119:          */
120:         __u32 md_magic;         /*  0 MD identifier                           */
121:         __u32 major_version;    /*  1 major version to which the set conforms */
122:         __u32 minor_version;    /*  2 minor version ...                       */
123:         __u32 patch_version;    /*  3 patchlevel version ...                  */
124:         __u32 gvalid_words;     /*  4 Number of used words in this section    */
125:         __u32 set_uuid0;        /*  5 Raid set identifier                     */
126:         __u32 ctime;            /*  6 Creation time                           */
127:         __u32 level;            /*  7 Raid personality                        */
128:         __u32 size;             /*  8 Apparent size of each individual disk   */
129:         __u32 nr_disks;         /*  9 total disks in the raid set             */
130:         __u32 raid_disks;       /* 10 disks in a fully functional raid set    */
131:         __u32 md_minor;         /* 11 preferred MD minor device number        */
132:         __u32 not_persistent;   /* 12 does it have a persistent superblock    */
133:         __u32 set_uuid1;        /* 13 Raid set identifier #2                  */
134:         __u32 set_uuid2;        /* 14 Raid set identifier #3                  */
135:         __u32 set_uuid3;        /* 15 Raid set identifier #4                  */
136:         __u32 gstate_creserved[MD_SB_GENERIC_CONSTANT_WORDS - 16];
137: 
138:         /*
139:          * Generic state information
140:          */
141:         __u32 utime;            /*  0 Superblock update time                  */
142:         __u32 state;            /*  1 State bits (clean, ...)                 */
143:         __u32 active_disks;     /*  2 Number of currently active disks        */
144:         __u32 working_disks;    /*  3 Number of working disks                 */
145:         __u32 failed_disks;     /*  4 Number of failed disks                  */
146:         __u32 spare_disks;      /*  5 Number of spare disks                   */
147:         __u32 sb_csum;          /*  6 checksum of the whole superblock        */
148: #ifdef __BIG_ENDIAN
149:         __u32 events_hi;        /*  7 high-order of superblock update count   */
150:         __u32 events_lo;        /*  8 low-order of superblock update count    */
151:         __u32 cp_events_hi;     /*  9 high-order of checkpoint update count   */
152:         __u32 cp_events_lo;     /* 10 low-order of checkpoint update count    */
153: #else
154:         __u32 events_lo;        /*  7 low-order of superblock update count    */
155:         __u32 events_hi;        /*  8 high-order of superblock update count   */
156:         __u32 cp_events_lo;     /*  9 low-order of checkpoint update count    */
157:         __u32 cp_events_hi;     /* 10 high-order of checkpoint update count   */
158: #endif
159:         __u32 recovery_cp;      /* 11 recovery checkpoint sector count        */
160:         /* There are only valid for minor_version > 90 */
161:         __u64 reshape_position; /* 12,13 next address in array-space for reshape */
162:         __u32 new_level;        /* 14 new level we are reshaping to           */
163:         __u32 delta_disks;      /* 15 change in number of raid_disks          */
164:         __u32 new_layout;       /* 16 new layout                              */
165:         __u32 new_chunk;        /* 17 new chunk size (bytes)                  */
166:         __u32 gstate_sreserved[MD_SB_GENERIC_STATE_WORDS - 18];
167: 
168:         /*
169:          * Personality information
170:          */
171:         __u32 layout;           /*  0 the array's physical layout             */
172:         __u32 chunk_size;       /*  1 chunk size in bytes                     */
173:         __u32 root_pv;          /*  2 LV root PV */
174:         __u32 root_block;       /*  3 LV root block */
175:         __u32 pstate_reserved[MD_SB_PERSONALITY_WORDS - 4];
176: 
177:         /*
178:          * Disks information
179:          */
180:         mdp_disk_t disks[MD_SB_DISKS];
181: 
182:         /*
183:          * Reserved
184:          */
185:         __u32 reserved[MD_SB_RESERVED_WORDS];
186: 
187:         /*
188:          * Active descriptor
189:          */
190:         mdp_disk_t this_disk;
191: 
192: } mdp_super_t;
193: 
194: static __inline__ __u64 md_event(mdp_super_t *sb) {
195:         __u64 ev = sb->events_hi;
196:         return (ev<<32)| sb->events_lo;
197: }
198: 
199: #define MD_SUPERBLOCK_1_TIME_SEC_MASK ((1ULL<<40) - 1)
200: 
201: /*
202:  * The version-1 superblock :
203:  * All numeric fields are little-endian.
204:  *
205:  * total size: 256 bytes plus 2 per device.
206:  *  1K allows 384 devices.
207:  */
208: struct mdp_superblock_1 {
209:         /* constant array information - 128 bytes */
210:         __le32  magic;          /* MD_SB_MAGIC: 0xa92b4efc - little endian */
211:         __le32  major_version;  /* 1 */
212:         __le32  feature_map;    /* bit 0 set if 'bitmap_offset' is meaningful */
213:         __le32  pad0;           /* always set to 0 when writing */
214: 
215:         __u8    set_uuid[16];   /* user-space generated. */
216:         char    set_name[32];   /* set and interpreted by user-space */
217: 
218:         __le64  ctime;          /* lo 40 bits are seconds, top 24 are microseconds or 0*/
219:         __le32  level;          /* -4 (multipath), -1 (linear), 0,1,4,5 */
220:         __le32  layout;         /* only for raid5 and raid10 currently */
221:         __le64  size;           /* used size of component devices, in 512byte sectors */
222: 
223:         __le32  chunksize;      /* in 512byte sectors */
224:         __le32  raid_disks;
225:         __le32  bitmap_offset;  /* sectors after start of superblock that bitmap starts
226:                                  * NOTE: signed, so bitmap can be before superblock
227:                                  * only meaningful of feature_map[0] is set.
228:                                  */
229: 
230:         /* These are only valid with feature bit '4' */
231:         __le32  new_level;      /* new level we are reshaping to                */
232:         __le64  reshape_position;       /* next address in array-space for reshape */
233:         __le32  delta_disks;    /* change in number of raid_disks               */
234:         __le32  new_layout;     /* new layout                                   */
235:         __le32  new_chunk;      /* new chunk size (512byte sectors)             */
236:         __u8    pad1[128-124];  /* set to 0 when written */
237: 
238:         /* constant this-device information - 64 bytes */
239:         __le64  data_offset;    /* sector start of data, often 0 */
240:         __le64  data_size;      /* sectors in this device that can be used for data */
241:         __le64  super_offset;   /* sector start of this superblock */
242:         __le64  recovery_offset;/* sectors before this offset (from data_offset) have been recovered */
243:         __le32  dev_number;     /* permanent identifier of this  device - not role in raid */
244:         __le32  cnt_corrected_read; /* number of read errors that were corrected by re-writing */
245:         __u8    device_uuid[16]; /* user-space setable, ignored by kernel */
246:         __u8    devflags;       /* per-device flags.  Only one defined...*/
247: #define WriteMostly1    1       /* mask for writemostly flag in above */
248:         /* Bad block log.  If there are any bad blocks the feature flag is set.
249:          * If offset and size are non-zero, that space is reserved and available
250:          */
251:         __u8    bblog_shift;    /* shift from sectors to block size */
252:         __le16  bblog_size;     /* number of sectors reserved for list */
253:         __le32  bblog_offset;   /* sector offset from superblock to bblog,
254:                                  * signed - not unsigned */
255: 
256:         /* array state information - 64 bytes */
257:         __le64  utime;          /* 40 bits second, 24 bits microseconds */
258:         __le64  events;         /* incremented when superblock updated */
259:         __le64  resync_offset;  /* data before this offset (from data_offset) known to be in sync */
260:         __le32  sb_csum;        /* checksum up to devs[max_dev] */
261:         __le32  max_dev;        /* size of devs[] array to consider */
262:         __u8    pad3[64-32];    /* set to 0 when writing */
263: 
264:         /* device state information. Indexed by dev_number.
265:          * 2 bytes per device
266:          * Note there are no per-device state flags. State information is rolled
267:          * into the 'roles' value.  If a device is spare or faulty, then it doesn't
268:          * have a meaningful role.
269:          */
270:         __le16  dev_roles[0];   /* role in array, or 0xffff for a spare, or 0xfffe for faulty */
271: };
272: 
273: /* feature_map bits */
274: #define MD_FEATURE_BITMAP_OFFSET        1
275: #define MD_FEATURE_RECOVERY_OFFSET      2 /* recovery_offset is present and
276:                                            * must be honoured
277:                                            */
278: #define MD_FEATURE_RESHAPE_ACTIVE       4
279: #define MD_FEATURE_BAD_BLOCKS           8 /* badblock list is not empty */
280: 
281: #define MD_FEATURE_ALL                  (1|2|4|8)
282: 
283: #endif 
284: 

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