1/* 2 * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003 3 * 4 * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc. 5 */ 6#ifndef BITMAP_H 7#define BITMAP_H 1 8 9#define BITMAP_MAJOR_LO 3 10/* version 4 insists the bitmap is in little-endian order 11 * with version 3, it is host-endian which is non-portable 12 */ 13#define BITMAP_MAJOR_HI 4 14#define BITMAP_MAJOR_HOSTENDIAN 3 15 16#define BITMAP_MINOR 39 17 18/* 19 * in-memory bitmap: 20 * 21 * Use 16 bit block counters to track pending writes to each "chunk". 22 * The 2 high order bits are special-purpose, the first is a flag indicating 23 * whether a resync is needed. The second is a flag indicating whether a 24 * resync is active. 25 * This means that the counter is actually 14 bits: 26 * 27 * +--------+--------+------------------------------------------------+ 28 * | resync | resync | counter | 29 * | needed | active | | 30 * | (0-1) | (0-1) | (0-16383) | 31 * +--------+--------+------------------------------------------------+ 32 * 33 * The "resync needed" bit is set when: 34 * a '1' bit is read from storage at startup. 35 * a write request fails on some drives 36 * a resync is aborted on a chunk with 'resync active' set 37 * It is cleared (and resync-active set) when a resync starts across all drives 38 * of the chunk. 39 * 40 * 41 * The "resync active" bit is set when: 42 * a resync is started on all drives, and resync_needed is set. 43 * resync_needed will be cleared (as long as resync_active wasn't already set). 44 * It is cleared when a resync completes. 45 * 46 * The counter counts pending write requests, plus the on-disk bit. 47 * When the counter is '1' and the resync bits are clear, the on-disk 48 * bit can be cleared aswell, thus setting the counter to 0. 49 * When we set a bit, or in the counter (to start a write), if the fields is 50 * 0, we first set the disk bit and set the counter to 1. 51 * 52 * If the counter is 0, the on-disk bit is clear and the stipe is clean 53 * Anything that dirties the stipe pushes the counter to 2 (at least) 54 * and sets the on-disk bit (lazily). 55 * If a periodic sweep find the counter at 2, it is decremented to 1. 56 * If the sweep find the counter at 1, the on-disk bit is cleared and the 57 * counter goes to zero. 58 * 59 * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block 60 * counters as a fallback when "page" memory cannot be allocated: 61 * 62 * Normal case (page memory allocated): 63 * 64 * page pointer (32-bit) 65 * 66 * [ ] ------+ 67 * | 68 * +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters) 69 * c1 c2 c2048 70 * 71 * Hijacked case (page memory allocation failed): 72 * 73 * hijacked page pointer (32-bit) 74 * 75 * [ ][ ] (no page memory allocated) 76 * counter #1 (16-bit) counter #2 (16-bit) 77 * 78 */ 79 80#ifdef __KERNEL__ 81 82#define PAGE_BITS (PAGE_SIZE << 3) 83#define PAGE_BIT_SHIFT (PAGE_SHIFT + 3) 84 85typedef __u16 bitmap_counter_t; 86#define COUNTER_BITS 16 87#define COUNTER_BIT_SHIFT 4 88#define COUNTER_BYTE_RATIO (COUNTER_BITS / 8) 89#define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3) 90 91#define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1))) 92#define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2))) 93#define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1) 94#define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK) 95#define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK) 96#define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX) 97 98/* how many counters per page? */ 99#define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS) 100/* same, except a shift value for more efficient bitops */ 101#define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT) 102/* same, except a mask value for more efficient bitops */ 103#define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1) 104 105#define BITMAP_BLOCK_SIZE 512 106#define BITMAP_BLOCK_SHIFT 9 107 108/* how many blocks per chunk? (this is variable) */ 109#define CHUNK_BLOCK_RATIO(bitmap) ((bitmap)->chunksize >> BITMAP_BLOCK_SHIFT) 110#define CHUNK_BLOCK_SHIFT(bitmap) ((bitmap)->chunkshift - BITMAP_BLOCK_SHIFT) 111#define CHUNK_BLOCK_MASK(bitmap) (CHUNK_BLOCK_RATIO(bitmap) - 1) 112 113/* when hijacked, the counters and bits represent even larger "chunks" */ 114/* there will be 1024 chunks represented by each counter in the page pointers */ 115#define PAGEPTR_BLOCK_RATIO(bitmap) \ 116 (CHUNK_BLOCK_RATIO(bitmap) << PAGE_COUNTER_SHIFT >> 1) 117#define PAGEPTR_BLOCK_SHIFT(bitmap) \ 118 (CHUNK_BLOCK_SHIFT(bitmap) + PAGE_COUNTER_SHIFT - 1) 119#define PAGEPTR_BLOCK_MASK(bitmap) (PAGEPTR_BLOCK_RATIO(bitmap) - 1) 120 121/* 122 * on-disk bitmap: 123 * 124 * Use one bit per "chunk" (block set). We do the disk I/O on the bitmap 125 * file a page at a time. There's a superblock at the start of the file. 126 */ 127 128/* map chunks (bits) to file pages - offset by the size of the superblock */ 129#define CHUNK_BIT_OFFSET(chunk) ((chunk) + (sizeof(bitmap_super_t) << 3)) 130 131#endif 132 133/* 134 * bitmap structures: 135 */ 136 137#define BITMAP_MAGIC 0x6d746962 138 139/* use these for bitmap->flags and bitmap->sb->state bit-fields */ 140enum bitmap_state { 141 BITMAP_ACTIVE = 0x001, /* the bitmap is in use */ 142 BITMAP_STALE = 0x002, /* the bitmap file is out of date or had -EIO */ 143 BITMAP_WRITE_ERROR = 0x004, /* A write error has occurred */ 144 BITMAP_HOSTENDIAN = 0x8000, 145}; 146 147/* the superblock at the front of the bitmap file -- little endian */ 148typedef struct bitmap_super_s { 149 __le32 magic; /* 0 BITMAP_MAGIC */ 150 __le32 version; /* 4 the bitmap major for now, could change... */ 151 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */ 152 __le64 events; /* 24 event counter for the bitmap (1)*/ 153 __le64 events_cleared;/*32 event counter when last bit cleared (2) */ 154 __le64 sync_size; /* 40 the size of the md device's sync range(3) */ 155 __le32 state; /* 48 bitmap state information */ 156 __le32 chunksize; /* 52 the bitmap chunk size in bytes */ 157 __le32 daemon_sleep; /* 56 seconds between disk flushes */ 158 __le32 write_behind; /* 60 number of outstanding write-behind writes */ 159 160 __u8 pad[256 - 64]; /* set to zero */ 161} bitmap_super_t; 162 163/* notes: 164 * (1) This event counter is updated before the eventcounter in the md superblock 165 * When a bitmap is loaded, it is only accepted if this event counter is equal 166 * to, or one greater than, the event counter in the superblock. 167 * (2) This event counter is updated when the other one is *if*and*only*if* the 168 * array is not degraded. As bits are not cleared when the array is degraded, 169 * this represents the last time that any bits were cleared. 170 * If a device is being added that has an event count with this value or 171 * higher, it is accepted as conforming to the bitmap. 172 * (3)This is the number of sectors represented by the bitmap, and is the range that 173 * resync happens across. For raid1 and raid5/6 it is the size of individual 174 * devices. For raid10 it is the size of the array. 175 */ 176 177#ifdef __KERNEL__ 178 179/* the in-memory bitmap is represented by bitmap_pages */ 180struct bitmap_page { 181 /* 182 * map points to the actual memory page 183 */ 184 char *map; 185 /* 186 * in emergencies (when map cannot be alloced), hijack the map 187 * pointer and use it as two counters itself 188 */ 189 unsigned int hijacked:1; 190 /* 191 * count of dirty bits on the page 192 */ 193 unsigned int count:31; 194}; 195 196/* keep track of bitmap file pages that have pending writes on them */ 197struct page_list { 198 struct list_head list; 199 struct page *page; 200}; 201 202/* the main bitmap structure - one per mddev */ 203struct bitmap { 204 struct bitmap_page *bp; 205 unsigned long pages; /* total number of pages in the bitmap */ 206 unsigned long missing_pages; /* number of pages not yet allocated */ 207 208 mddev_t *mddev; /* the md device that the bitmap is for */ 209 210 int counter_bits; /* how many bits per block counter */ 211 212 /* bitmap chunksize -- how much data does each bit represent? */ 213 unsigned long chunksize; 214 unsigned long chunkshift; /* chunksize = 2^chunkshift (for bitops) */ 215 unsigned long chunks; /* total number of data chunks for the array */ 216 217 /* We hold a count on the chunk currently being synced, and drop 218 * it when the last block is started. If the resync is aborted 219 * midway, we need to be able to drop that count, so we remember 220 * the counted chunk.. 221 */ 222 unsigned long syncchunk; 223 224 __u64 events_cleared; 225 226 /* bitmap spinlock */ 227 spinlock_t lock; 228 229 long offset; /* offset from superblock if file is NULL */ 230 struct file *file; /* backing disk file */ 231 struct page *sb_page; /* cached copy of the bitmap file superblock */ 232 struct page **filemap; /* list of cache pages for the file */ 233 unsigned long *filemap_attr; /* attributes associated w/ filemap pages */ 234 unsigned long file_pages; /* number of pages in the file */ 235 int last_page_size; /* bytes in the last page */ 236 237 unsigned long flags; 238 239 unsigned long max_write_behind; /* write-behind mode */ 240 atomic_t behind_writes; 241 242 /* 243 * the bitmap daemon - periodically wakes up and sweeps the bitmap 244 * file, cleaning up bits and flushing out pages to disk as necessary 245 */ 246 unsigned long daemon_lastrun; /* jiffies of last run */ 247 unsigned long daemon_sleep; /* how many seconds between updates? */ 248 249 atomic_t pending_writes; /* pending writes to the bitmap file */ 250 wait_queue_head_t write_wait; 251 wait_queue_head_t overflow_wait; 252 253}; 254 255/* the bitmap API */ 256 257/* these are used only by md/bitmap */ 258int bitmap_create(mddev_t *mddev); 259void bitmap_flush(mddev_t *mddev); 260void bitmap_destroy(mddev_t *mddev); 261int bitmap_active(struct bitmap *bitmap); 262 263char *file_path(struct file *file, char *buf, int count); 264void bitmap_print_sb(struct bitmap *bitmap); 265int bitmap_update_sb(struct bitmap *bitmap); 266 267int bitmap_setallbits(struct bitmap *bitmap); 268void bitmap_write_all(struct bitmap *bitmap); 269 270void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e); 271 272/* these are exported */ 273int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, 274 unsigned long sectors, int behind); 275void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, 276 unsigned long sectors, int success, int behind); 277int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int degraded); 278void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int aborted); 279void bitmap_close_sync(struct bitmap *bitmap); 280 281int bitmap_unplug(struct bitmap *bitmap); 282int bitmap_daemon_work(struct bitmap *bitmap); 283#endif 284 285#endif 286