1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * bitmap.h: Copyright (C) Peter T. Breuer (ptb@ot.uc3m.es) 2003 4 * 5 * additions: Copyright (C) 2003-2004, Paul Clements, SteelEye Technology, Inc. 6 */ 7 #ifndef BITMAP_H 8 #define BITMAP_H 1 9 10 #define BITMAP_MAJOR_LO 3 11 /* version 4 insists the bitmap is in little-endian order 12 * with version 3, it is host-endian which is non-portable 13 * Version 5 is currently set only for clustered devices 14 */ 15 #define BITMAP_MAJOR_HI 4 16 #define BITMAP_MAJOR_CLUSTERED 5 17 #define BITMAP_MAJOR_HOSTENDIAN 3 18 19 /* 20 * in-memory bitmap: 21 * 22 * Use 16 bit block counters to track pending writes to each "chunk". 23 * The 2 high order bits are special-purpose, the first is a flag indicating 24 * whether a resync is needed. The second is a flag indicating whether a 25 * resync is active. 26 * This means that the counter is actually 14 bits: 27 * 28 * +--------+--------+------------------------------------------------+ 29 * | resync | resync | counter | 30 * | needed | active | | 31 * | (0-1) | (0-1) | (0-16383) | 32 * +--------+--------+------------------------------------------------+ 33 * 34 * The "resync needed" bit is set when: 35 * a '1' bit is read from storage at startup. 36 * a write request fails on some drives 37 * a resync is aborted on a chunk with 'resync active' set 38 * It is cleared (and resync-active set) when a resync starts across all drives 39 * of the chunk. 40 * 41 * 42 * The "resync active" bit is set when: 43 * a resync is started on all drives, and resync_needed is set. 44 * resync_needed will be cleared (as long as resync_active wasn't already set). 45 * It is cleared when a resync completes. 46 * 47 * The counter counts pending write requests, plus the on-disk bit. 48 * When the counter is '1' and the resync bits are clear, the on-disk 49 * bit can be cleared as well, thus setting the counter to 0. 50 * When we set a bit, or in the counter (to start a write), if the fields is 51 * 0, we first set the disk bit and set the counter to 1. 52 * 53 * If the counter is 0, the on-disk bit is clear and the stripe is clean 54 * Anything that dirties the stripe pushes the counter to 2 (at least) 55 * and sets the on-disk bit (lazily). 56 * If a periodic sweep find the counter at 2, it is decremented to 1. 57 * If the sweep find the counter at 1, the on-disk bit is cleared and the 58 * counter goes to zero. 59 * 60 * Also, we'll hijack the "map" pointer itself and use it as two 16 bit block 61 * counters as a fallback when "page" memory cannot be allocated: 62 * 63 * Normal case (page memory allocated): 64 * 65 * page pointer (32-bit) 66 * 67 * [ ] ------+ 68 * | 69 * +-------> [ ][ ]..[ ] (4096 byte page == 2048 counters) 70 * c1 c2 c2048 71 * 72 * Hijacked case (page memory allocation failed): 73 * 74 * hijacked page pointer (32-bit) 75 * 76 * [ ][ ] (no page memory allocated) 77 * counter #1 (16-bit) counter #2 (16-bit) 78 * 79 */ 80 81 #ifdef __KERNEL__ 82 83 #define PAGE_BITS (PAGE_SIZE << 3) 84 #define PAGE_BIT_SHIFT (PAGE_SHIFT + 3) 85 86 typedef __u16 bitmap_counter_t; 87 #define COUNTER_BITS 16 88 #define COUNTER_BIT_SHIFT 4 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_SHIFT 9 106 107 #endif 108 109 /* 110 * bitmap structures: 111 */ 112 113 #define BITMAP_MAGIC 0x6d746962 114 115 /* use these for bitmap->flags and bitmap->sb->state bit-fields */ 116 enum bitmap_state { 117 BITMAP_STALE = 1, /* the bitmap file is out of date or had -EIO */ 118 BITMAP_WRITE_ERROR = 2, /* A write error has occurred */ 119 BITMAP_HOSTENDIAN =15, 120 }; 121 122 /* the superblock at the front of the bitmap file -- little endian */ 123 typedef struct bitmap_super_s { 124 __le32 magic; /* 0 BITMAP_MAGIC */ 125 __le32 version; /* 4 the bitmap major for now, could change... */ 126 __u8 uuid[16]; /* 8 128 bit uuid - must match md device uuid */ 127 __le64 events; /* 24 event counter for the bitmap (1)*/ 128 __le64 events_cleared;/*32 event counter when last bit cleared (2) */ 129 __le64 sync_size; /* 40 the size of the md device's sync range(3) */ 130 __le32 state; /* 48 bitmap state information */ 131 __le32 chunksize; /* 52 the bitmap chunk size in bytes */ 132 __le32 daemon_sleep; /* 56 seconds between disk flushes */ 133 __le32 write_behind; /* 60 number of outstanding write-behind writes */ 134 __le32 sectors_reserved; /* 64 number of 512-byte sectors that are 135 * reserved for the bitmap. */ 136 __le32 nodes; /* 68 the maximum number of nodes in cluster. */ 137 __u8 cluster_name[64]; /* 72 cluster name to which this md belongs */ 138 __u8 pad[256 - 136]; /* set to zero */ 139 } bitmap_super_t; 140 141 /* notes: 142 * (1) This event counter is updated before the eventcounter in the md superblock 143 * When a bitmap is loaded, it is only accepted if this event counter is equal 144 * to, or one greater than, the event counter in the superblock. 145 * (2) This event counter is updated when the other one is *if*and*only*if* the 146 * array is not degraded. As bits are not cleared when the array is degraded, 147 * this represents the last time that any bits were cleared. 148 * If a device is being added that has an event count with this value or 149 * higher, it is accepted as conforming to the bitmap. 150 * (3)This is the number of sectors represented by the bitmap, and is the range that 151 * resync happens across. For raid1 and raid5/6 it is the size of individual 152 * devices. For raid10 it is the size of the array. 153 */ 154 155 #ifdef __KERNEL__ 156 157 /* the in-memory bitmap is represented by bitmap_pages */ 158 struct bitmap_page { 159 /* 160 * map points to the actual memory page 161 */ 162 char *map; 163 /* 164 * in emergencies (when map cannot be alloced), hijack the map 165 * pointer and use it as two counters itself 166 */ 167 unsigned int hijacked:1; 168 /* 169 * If any counter in this page is '1' or '2' - and so could be 170 * cleared then that page is marked as 'pending' 171 */ 172 unsigned int pending:1; 173 /* 174 * count of dirty bits on the page 175 */ 176 unsigned int count:30; 177 }; 178 179 /* the main bitmap structure - one per mddev */ 180 struct bitmap { 181 182 struct bitmap_counts { 183 spinlock_t lock; 184 struct bitmap_page *bp; 185 unsigned long pages; /* total number of pages 186 * in the bitmap */ 187 unsigned long missing_pages; /* number of pages 188 * not yet allocated */ 189 unsigned long chunkshift; /* chunksize = 2^chunkshift 190 * (for bitops) */ 191 unsigned long chunks; /* Total number of data 192 * chunks for the array */ 193 } counts; 194 195 struct mddev *mddev; /* the md device that the bitmap is for */ 196 197 __u64 events_cleared; 198 int need_sync; 199 200 struct bitmap_storage { 201 struct file *file; /* backing disk file */ 202 struct page *sb_page; /* cached copy of the bitmap 203 * file superblock */ 204 struct page **filemap; /* list of cache pages for 205 * the file */ 206 unsigned long *filemap_attr; /* attributes associated 207 * w/ filemap pages */ 208 unsigned long file_pages; /* number of pages in the file*/ 209 unsigned long bytes; /* total bytes in the bitmap */ 210 } storage; 211 212 unsigned long flags; 213 214 int allclean; 215 216 atomic_t behind_writes; 217 unsigned long behind_writes_used; /* highest actual value at runtime */ 218 219 /* 220 * the bitmap daemon - periodically wakes up and sweeps the bitmap 221 * file, cleaning up bits and flushing out pages to disk as necessary 222 */ 223 unsigned long daemon_lastrun; /* jiffies of last run */ 224 unsigned long last_end_sync; /* when we lasted called end_sync to 225 * update bitmap with resync progress */ 226 227 atomic_t pending_writes; /* pending writes to the bitmap file */ 228 wait_queue_head_t write_wait; 229 wait_queue_head_t overflow_wait; 230 wait_queue_head_t behind_wait; 231 232 struct kernfs_node *sysfs_can_clear; 233 int cluster_slot; /* Slot offset for clustered env */ 234 }; 235 236 /* the bitmap API */ 237 238 /* these are used only by md/bitmap */ 239 struct bitmap *md_bitmap_create(struct mddev *mddev, int slot); 240 int md_bitmap_load(struct mddev *mddev); 241 void md_bitmap_flush(struct mddev *mddev); 242 void md_bitmap_destroy(struct mddev *mddev); 243 244 void md_bitmap_print_sb(struct bitmap *bitmap); 245 void md_bitmap_update_sb(struct bitmap *bitmap); 246 void md_bitmap_status(struct seq_file *seq, struct bitmap *bitmap); 247 248 int md_bitmap_setallbits(struct bitmap *bitmap); 249 void md_bitmap_write_all(struct bitmap *bitmap); 250 251 void md_bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e); 252 253 /* these are exported */ 254 int md_bitmap_startwrite(struct bitmap *bitmap, sector_t offset, 255 unsigned long sectors, int behind); 256 void md_bitmap_endwrite(struct bitmap *bitmap, sector_t offset, 257 unsigned long sectors, int success, int behind); 258 int md_bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded); 259 void md_bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted); 260 void md_bitmap_close_sync(struct bitmap *bitmap); 261 void md_bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force); 262 void md_bitmap_sync_with_cluster(struct mddev *mddev, 263 sector_t old_lo, sector_t old_hi, 264 sector_t new_lo, sector_t new_hi); 265 266 void md_bitmap_unplug(struct bitmap *bitmap); 267 void md_bitmap_unplug_async(struct bitmap *bitmap); 268 void md_bitmap_daemon_work(struct mddev *mddev); 269 270 int md_bitmap_resize(struct bitmap *bitmap, sector_t blocks, 271 int chunksize, int init); 272 struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot); 273 int md_bitmap_copy_from_slot(struct mddev *mddev, int slot, 274 sector_t *lo, sector_t *hi, bool clear_bits); 275 void md_bitmap_free(struct bitmap *bitmap); 276 void md_bitmap_wait_behind_writes(struct mddev *mddev); 277 278 static inline bool md_bitmap_enabled(struct bitmap *bitmap) 279 { 280 return bitmap && bitmap->storage.filemap && 281 !test_bit(BITMAP_STALE, &bitmap->flags); 282 } 283 284 #endif 285 286 #endif 287