drivers/md/raid1.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _RAID1_H
   3 #define _RAID1_H
   4
   5 /*
   6  * each barrier unit size is 64MB fow now
   7  * note: it must be larger than RESYNC_DEPTH
   8  */
   9 #define BARRIER_UNIT_SECTOR_BITS        17
  10 #define BARRIER_UNIT_SECTOR_SIZE        (1<<17)
  11 /*
  12  * In struct r1conf, the following members are related to I/O barrier
  13  * buckets,
  14  *      atomic_t        *nr_pending;
  15  *      atomic_t        *nr_waiting;
  16  *      atomic_t        *nr_queued;
  17  *      atomic_t        *barrier;
  18  * Each of them points to array of atomic_t variables, each array is
  19  * designed to have BARRIER_BUCKETS_NR elements and occupy a single
  20  * memory page. The data width of atomic_t variables is 4 bytes, equal
  21  * to 1<<(ilog2(sizeof(atomic_t))), BARRIER_BUCKETS_NR_BITS is defined
  22  * as (PAGE_SHIFT - ilog2(sizeof(int))) to make sure an array of
  23  * atomic_t variables with BARRIER_BUCKETS_NR elements just exactly
  24  * occupies a single memory page.
  25  */
  26 #define BARRIER_BUCKETS_NR_BITS         (PAGE_SHIFT - ilog2(sizeof(atomic_t)))
  27 #define BARRIER_BUCKETS_NR              (1<<BARRIER_BUCKETS_NR_BITS)
  28
  29 struct raid1_info {
  30         struct md_rdev  *rdev;
  31         sector_t        head_position;
  32
  33         /* When choose the best device for a read (read_balance())
  34          * we try to keep sequential reads one the same device
  35          */
  36         sector_t        next_seq_sect;
  37         sector_t        seq_start;
  38 };
  39
  40 /*
  41  * memory pools need a pointer to the mddev, so they can force an unplug
  42  * when memory is tight, and a count of the number of drives that the
  43  * pool was allocated for, so they know how much to allocate and free.
  44  * mddev->raid_disks cannot be used, as it can change while a pool is active
  45  * These two datums are stored in a kmalloced struct.
  46  * The 'raid_disks' here is twice the raid_disks in r1conf.
  47  * This allows space for each 'real' device can have a replacement in the
  48  * second half of the array.
  49  */
  50
  51 struct pool_info {
  52         struct mddev *mddev;
  53         int     raid_disks;
  54 };
  55
  56 struct r1conf {
  57         struct mddev            *mddev;
  58         struct raid1_info       *mirrors;       /* twice 'raid_disks' to
  59                                                  * allow for replacements.
  60                                                  */
  61         int                     raid_disks;
  62
  63         spinlock_t              device_lock;
  64
  65         /* list of 'struct r1bio' that need to be processed by raid1d,
  66          * whether to retry a read, writeout a resync or recovery
  67          * block, or anything else.
  68          */
  69         struct list_head        retry_list;
  70         /* A separate list of r1bio which just need raid_end_bio_io called.
  71          * This mustn't happen for writes which had any errors if the superblock
  72          * needs to be written.
  73          */
  74         struct list_head        bio_end_io_list;
  75
  76         /* queue pending writes to be submitted on unplug */
  77         struct bio_list         pending_bio_list;
  78         int                     pending_count;
  79
  80         /* for use when syncing mirrors:
  81          * We don't allow both normal IO and resync/recovery IO at
  82          * the same time - resync/recovery can only happen when there
  83          * is no other IO.  So when either is active, the other has to wait.
  84          * See more details description in raid1.c near raise_barrier().
  85          */
  86         wait_queue_head_t       wait_barrier;
  87         spinlock_t              resync_lock;
  88         atomic_t                nr_sync_pending;
  89         atomic_t                *nr_pending;
  90         atomic_t                *nr_waiting;
  91         atomic_t                *nr_queued;
  92         atomic_t                *barrier;
  93         int                     array_frozen;
  94
  95         /* Set to 1 if a full sync is needed, (fresh device added).
  96          * Cleared when a sync completes.
  97          */
  98         int                     fullsync;
  99
 100         /* When the same as mddev->recovery_disabled we don't allow
 101          * recovery to be attempted as we expect a read error.
 102          */
 103         int                     recovery_disabled;
 104
 105         /* poolinfo contains information about the content of the
 106          * mempools - it changes when the array grows or shrinks
 107          */
 108         struct pool_info        *poolinfo;
 109         mempool_t               *r1bio_pool;
 110         mempool_t               *r1buf_pool;
 111
 112         struct bio_set          *bio_split;
 113
 114         /* temporary buffer to synchronous IO when attempting to repair
 115          * a read error.
 116          */
 117         struct page             *tmppage;
 118
 119         /* When taking over an array from a different personality, we store
 120          * the new thread here until we fully activate the array.
 121          */
 122         struct md_thread        *thread;
 123
 124         /* Keep track of cluster resync window to send to other
 125          * nodes.
 126          */
 127         sector_t                cluster_sync_low;
 128         sector_t                cluster_sync_high;
 129
 130 };
 131
 132 /*
 133  * this is our 'private' RAID1 bio.
 134  *
 135  * it contains information about what kind of IO operations were started
 136  * for this RAID1 operation, and about their status:
 137  */
 138
 139 struct r1bio {
 140         atomic_t                remaining; /* 'have we finished' count,
 141                                             * used from IRQ handlers
 142                                             */
 143         atomic_t                behind_remaining; /* number of write-behind ios remaining
 144                                                  * in this BehindIO request
 145                                                  */
 146         sector_t                sector;
 147         int                     sectors;
 148         unsigned long           state;
 149         struct mddev            *mddev;
 150         /*
 151          * original bio going to /dev/mdx
 152          */
 153         struct bio              *master_bio;
 154         /*
 155          * if the IO is in READ direction, then this is where we read
 156          */
 157         int                     read_disk;
 158
 159         struct list_head        retry_list;
 160
 161         /*
 162          * When R1BIO_BehindIO is set, we store pages for write behind
 163          * in behind_master_bio.
 164          */
 165         struct bio              *behind_master_bio;
 166
 167         /*
 168          * if the IO is in WRITE direction, then multiple bios are used.
 169          * We choose the number when they are allocated.
 170          */
 171         struct bio              *bios[0];
 172         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 173 };
 174
 175 /* bits for r1bio.state */
 176 enum r1bio_state {
 177         R1BIO_Uptodate,
 178         R1BIO_IsSync,
 179         R1BIO_Degraded,
 180         R1BIO_BehindIO,
 181 /* Set ReadError on bios that experience a readerror so that
 182  * raid1d knows what to do with them.
 183  */
 184         R1BIO_ReadError,
 185 /* For write-behind requests, we call bi_end_io when
 186  * the last non-write-behind device completes, providing
 187  * any write was successful.  Otherwise we call when
 188  * any write-behind write succeeds, otherwise we call
 189  * with failure when last write completes (and all failed).
 190  * Record that bi_end_io was called with this flag...
 191  */
 192         R1BIO_Returned,
 193 /* If a write for this request means we can clear some
 194  * known-bad-block records, we set this flag
 195  */
 196         R1BIO_MadeGood,
 197         R1BIO_WriteError,
 198         R1BIO_FailFast,
 199 };
 200
 201 static inline int sector_to_idx(sector_t sector)
 202 {
 203         return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
 204                          BARRIER_BUCKETS_NR_BITS);
 205 }
 206 #endif