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