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 * Version 5 is currently set only for clustered devices 13 */ 14 #define BITMAP_MAJOR_HI 4 15 #define BITMAP_MAJOR_CLUSTERED 5 16 #define BITMAP_MAJOR_HOSTENDIAN 3 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 as well, 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 stripe is clean 53 * Anything that dirties the stripe 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 85 typedef __u16 bitmap_counter_t; 86 #define COUNTER_BITS 16 87 #define COUNTER_BIT_SHIFT 4 88 #define COUNTER_BYTE_SHIFT (COUNTER_BIT_SHIFT - 3) 89 90 #define NEEDED_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 1))) 91 #define RESYNC_MASK ((bitmap_counter_t) (1 << (COUNTER_BITS - 2))) 92 #define COUNTER_MAX ((bitmap_counter_t) RESYNC_MASK - 1) 93 #define NEEDED(x) (((bitmap_counter_t) x) & NEEDED_MASK) 94 #define RESYNC(x) (((bitmap_counter_t) x) & RESYNC_MASK) 95 #define COUNTER(x) (((bitmap_counter_t) x) & COUNTER_MAX) 96 97 /* how many counters per page? */ 98 #define PAGE_COUNTER_RATIO (PAGE_BITS / COUNTER_BITS) 99 /* same, except a shift value for more efficient bitops */ 100 #define PAGE_COUNTER_SHIFT (PAGE_BIT_SHIFT - COUNTER_BIT_SHIFT) 101 /* same, except a mask value for more efficient bitops */ 102 #define PAGE_COUNTER_MASK (PAGE_COUNTER_RATIO - 1) 103 104 #define BITMAP_BLOCK_SHIFT 9 105 106 #endif 107 108 /* 109 * bitmap structures: 110 */ 111 112 #define BITMAP_MAGIC 0x6d746962 113 114 /* use these for bitmap->flags and bitmap->sb->state bit-fields */ 115 enum bitmap_state { 116 BITMAP_STALE = 1, /* the bitmap file is out of date or had -EIO */ 117 BITMAP_WRITE_ERROR = 2, /* A write error has occurred */ 118 BITMAP_HOSTENDIAN =15, 119 }; 120 121 /* the superblock at the front of the bitmap file -- little endian */ 122 typedef struct bitmap_super_s { 123 __le32 magic; /* 0 BITMAP_MAGIC */ 124 __le32 version; /* 4 the bitmap major for now, could change... */ 125 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */ 126 __le64 events; /* 24 event counter for the bitmap (1)*/ 127 __le64 events_cleared;/*32 event counter when last bit cleared (2) */ 128 __le64 sync_size; /* 40 the size of the md device's sync range(3) */ 129 __le32 state; /* 48 bitmap state information */ 130 __le32 chunksize; /* 52 the bitmap chunk size in bytes */ 131 __le32 daemon_sleep; /* 56 seconds between disk flushes */ 132 __le32 write_behind; /* 60 number of outstanding write-behind writes */ 133 __le32 sectors_reserved; /* 64 number of 512-byte sectors that are 134 * reserved for the bitmap. */ 135 __le32 nodes; /* 68 the maximum number of nodes in cluster. */ 136 __u8 cluster_name[64]; /* 72 cluster name to which this md belongs */ 137 __u8 pad[256 - 136]; /* set to zero */ 138 } bitmap_super_t; 139 140 /* notes: 141 * (1) This event counter is updated before the eventcounter in the md superblock 142 * When a bitmap is loaded, it is only accepted if this event counter is equal 143 * to, or one greater than, the event counter in the superblock. 144 * (2) This event counter is updated when the other one is *if*and*only*if* the 145 * array is not degraded. As bits are not cleared when the array is degraded, 146 * this represents the last time that any bits were cleared. 147 * If a device is being added that has an event count with this value or 148 * higher, it is accepted as conforming to the bitmap. 149 * (3)This is the number of sectors represented by the bitmap, and is the range that 150 * resync happens across. For raid1 and raid5/6 it is the size of individual 151 * devices. For raid10 it is the size of the array. 152 */ 153 154 #ifdef __KERNEL__ 155 156 /* the in-memory bitmap is represented by bitmap_pages */ 157 struct bitmap_page { 158 /* 159 * map points to the actual memory page 160 */ 161 char *map; 162 /* 163 * in emergencies (when map cannot be alloced), hijack the map 164 * pointer and use it as two counters itself 165 */ 166 unsigned int hijacked:1; 167 /* 168 * If any counter in this page is '1' or '2' - and so could be 169 * cleared then that page is marked as 'pending' 170 */ 171 unsigned int pending:1; 172 /* 173 * count of dirty bits on the page 174 */ 175 unsigned int count:30; 176 }; 177 178 /* the main bitmap structure - one per mddev */ 179 struct bitmap { 180 181 struct bitmap_counts { 182 spinlock_t lock; 183 struct bitmap_page *bp; 184 unsigned long pages; /* total number of pages 185 * in the bitmap */ 186 unsigned long missing_pages; /* number of pages 187 * not yet allocated */ 188 unsigned long chunkshift; /* chunksize = 2^chunkshift 189 * (for bitops) */ 190 unsigned long chunks; /* Total number of data 191 * chunks for the array */ 192 } counts; 193 194 struct mddev *mddev; /* the md device that the bitmap is for */ 195 196 __u64 events_cleared; 197 int need_sync; 198 199 struct bitmap_storage { 200 struct file *file; /* backing disk file */ 201 struct page *sb_page; /* cached copy of the bitmap 202 * file superblock */ 203 struct page **filemap; /* list of cache pages for 204 * the file */ 205 unsigned long *filemap_attr; /* attributes associated 206 * w/ filemap pages */ 207 unsigned long file_pages; /* number of pages in the file*/ 208 unsigned long bytes; /* total bytes in the bitmap */ 209 } storage; 210 211 unsigned long flags; 212 213 int allclean; 214 215 atomic_t behind_writes; 216 unsigned long behind_writes_used; /* highest actual value at runtime */ 217 218 /* 219 * the bitmap daemon - periodically wakes up and sweeps the bitmap 220 * file, cleaning up bits and flushing out pages to disk as necessary 221 */ 222 unsigned long daemon_lastrun; /* jiffies of last run */ 223 unsigned long last_end_sync; /* when we lasted called end_sync to 224 * update bitmap with resync progress */ 225 226 atomic_t pending_writes; /* pending writes to the bitmap file */ 227 wait_queue_head_t write_wait; 228 wait_queue_head_t overflow_wait; 229 wait_queue_head_t behind_wait; 230 231 struct kernfs_node *sysfs_can_clear; 232 int cluster_slot; /* Slot offset for clustered env */ 233 }; 234 235 /* the bitmap API */ 236 237 /* these are used only by md/bitmap */ 238 struct bitmap *bitmap_create(struct mddev *mddev, int slot); 239 int bitmap_load(struct mddev *mddev); 240 void bitmap_flush(struct mddev *mddev); 241 void bitmap_destroy(struct mddev *mddev); 242 243 void bitmap_print_sb(struct bitmap *bitmap); 244 void bitmap_update_sb(struct bitmap *bitmap); 245 void bitmap_status(struct seq_file *seq, struct bitmap *bitmap); 246 247 int bitmap_setallbits(struct bitmap *bitmap); 248 void bitmap_write_all(struct bitmap *bitmap); 249 250 void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e); 251 252 /* these are exported */ 253 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, 254 unsigned long sectors, int behind); 255 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, 256 unsigned long sectors, int success, int behind); 257 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded); 258 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted); 259 void bitmap_close_sync(struct bitmap *bitmap); 260 void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force); 261 void bitmap_sync_with_cluster(struct mddev *mddev, 262 sector_t old_lo, sector_t old_hi, 263 sector_t new_lo, sector_t new_hi); 264 265 void bitmap_unplug(struct bitmap *bitmap); 266 void bitmap_daemon_work(struct mddev *mddev); 267 268 int bitmap_resize(struct bitmap *bitmap, sector_t blocks, 269 int chunksize, int init); 270 int bitmap_copy_from_slot(struct mddev *mddev, int slot, 271 sector_t *lo, sector_t *hi, bool clear_bits); 272 #endif 273 274 #endif 275