drivers/md/md-bitmap.h

   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 *bitmap_create(struct mddev *mddev, int slot);
 240 int bitmap_load(struct mddev *mddev);
 241 void bitmap_flush(struct mddev *mddev);
 242 void bitmap_destroy(struct mddev *mddev);
 243
 244 void bitmap_print_sb(struct bitmap *bitmap);
 245 void bitmap_update_sb(struct bitmap *bitmap);
 246 void bitmap_status(struct seq_file *seq, struct bitmap *bitmap);
 247
 248 int  bitmap_setallbits(struct bitmap *bitmap);
 249 void bitmap_write_all(struct bitmap *bitmap);
 250
 251 void bitmap_dirty_bits(struct bitmap *bitmap, unsigned long s, unsigned long e);
 252
 253 /* these are exported */
 254 int bitmap_startwrite(struct bitmap *bitmap, sector_t offset,
 255                         unsigned long sectors, int behind);
 256 void bitmap_endwrite(struct bitmap *bitmap, sector_t offset,
 257                         unsigned long sectors, int success, int behind);
 258 int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int degraded);
 259 void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, sector_t *blocks, int aborted);
 260 void bitmap_close_sync(struct bitmap *bitmap);
 261 void bitmap_cond_end_sync(struct bitmap *bitmap, sector_t sector, bool force);
 262 void 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 bitmap_unplug(struct bitmap *bitmap);
 267 void bitmap_daemon_work(struct mddev *mddev);
 268
 269 int bitmap_resize(struct bitmap *bitmap, sector_t blocks,
 270                   int chunksize, int init);
 271 struct bitmap *get_bitmap_from_slot(struct mddev *mddev, int slot);
 272 int bitmap_copy_from_slot(struct mddev *mddev, int slot,
 273                                 sector_t *lo, sector_t *hi, bool clear_bits);
 274 void bitmap_free(struct bitmap *bitmap);
 275 void bitmap_wait_behind_writes(struct mddev *mddev);
 276 #endif
 277
 278 #endif