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 /* Note: raid1_info.rdev can be set to NULL asynchronously by raid1_remove_disk.
  30  * There are three safe ways to access raid1_info.rdev.
  31  * 1/ when holding mddev->reconfig_mutex
  32  * 2/ when resync/recovery is known to be happening - i.e. in code that is
  33  *    called as part of performing resync/recovery.
  34  * 3/ while holding rcu_read_lock(), use rcu_dereference to get the pointer
  35  *    and if it is non-NULL, increment rdev->nr_pending before dropping the
  36  *    RCU lock.
  37  * When .rdev is set to NULL, the nr_pending count checked again and if it has
  38  * been incremented, the pointer is put back in .rdev.
  39  */
  40
  41 struct raid1_info {
  42         struct md_rdev  *rdev;
  43         sector_t        head_position;
  44
  45         /* When choose the best device for a read (read_balance())
  46          * we try to keep sequential reads one the same device
  47          */
  48         sector_t        next_seq_sect;
  49         sector_t        seq_start;
  50 };
  51
  52 /*
  53  * memory pools need a pointer to the mddev, so they can force an unplug
  54  * when memory is tight, and a count of the number of drives that the
  55  * pool was allocated for, so they know how much to allocate and free.
  56  * mddev->raid_disks cannot be used, as it can change while a pool is active
  57  * These two datums are stored in a kmalloced struct.
  58  * The 'raid_disks' here is twice the raid_disks in r1conf.
  59  * This allows space for each 'real' device can have a replacement in the
  60  * second half of the array.
  61  */
  62
  63 struct pool_info {
  64         struct mddev *mddev;
  65         int     raid_disks;
  66 };
  67
  68 struct r1conf {
  69         struct mddev            *mddev;
  70         struct raid1_info       *mirrors;       /* twice 'raid_disks' to
  71                                                  * allow for replacements.
  72                                                  */
  73         int                     raid_disks;
  74
  75         spinlock_t              device_lock;
  76
  77         /* list of 'struct r1bio' that need to be processed by raid1d,
  78          * whether to retry a read, writeout a resync or recovery
  79          * block, or anything else.
  80          */
  81         struct list_head        retry_list;
  82         /* A separate list of r1bio which just need raid_end_bio_io called.
  83          * This mustn't happen for writes which had any errors if the superblock
  84          * needs to be written.
  85          */
  86         struct list_head        bio_end_io_list;
  87
  88         /* queue pending writes to be submitted on unplug */
  89         struct bio_list         pending_bio_list;
  90         int                     pending_count;
  91
  92         /* for use when syncing mirrors:
  93          * We don't allow both normal IO and resync/recovery IO at
  94          * the same time - resync/recovery can only happen when there
  95          * is no other IO.  So when either is active, the other has to wait.
  96          * See more details description in raid1.c near raise_barrier().
  97          */
  98         wait_queue_head_t       wait_barrier;
  99         spinlock_t              resync_lock;
 100         atomic_t                nr_sync_pending;
 101         atomic_t                *nr_pending;
 102         atomic_t                *nr_waiting;
 103         atomic_t                *nr_queued;
 104         atomic_t                *barrier;
 105         int                     array_frozen;
 106
 107         /* Set to 1 if a full sync is needed, (fresh device added).
 108          * Cleared when a sync completes.
 109          */
 110         int                     fullsync;
 111
 112         /* When the same as mddev->recovery_disabled we don't allow
 113          * recovery to be attempted as we expect a read error.
 114          */
 115         int                     recovery_disabled;
 116
 117         /* poolinfo contains information about the content of the
 118          * mempools - it changes when the array grows or shrinks
 119          */
 120         struct pool_info        *poolinfo;
 121         mempool_t               r1bio_pool;
 122         mempool_t               r1buf_pool;
 123
 124         struct bio_set          bio_split;
 125
 126         /* temporary buffer to synchronous IO when attempting to repair
 127          * a read error.
 128          */
 129         struct page             *tmppage;
 130
 131         /* When taking over an array from a different personality, we store
 132          * the new thread here until we fully activate the array.
 133          */
 134         struct md_thread        *thread;
 135
 136         /* Keep track of cluster resync window to send to other
 137          * nodes.
 138          */
 139         sector_t                cluster_sync_low;
 140         sector_t                cluster_sync_high;
 141
 142 };
 143
 144 /*
 145  * this is our 'private' RAID1 bio.
 146  *
 147  * it contains information about what kind of IO operations were started
 148  * for this RAID1 operation, and about their status:
 149  */
 150
 151 struct r1bio {
 152         atomic_t                remaining; /* 'have we finished' count,
 153                                             * used from IRQ handlers
 154                                             */
 155         atomic_t                behind_remaining; /* number of write-behind ios remaining
 156                                                  * in this BehindIO request
 157                                                  */
 158         sector_t                sector;
 159         int                     sectors;
 160         unsigned long           state;
 161         struct mddev            *mddev;
 162         /*
 163          * original bio going to /dev/mdx
 164          */
 165         struct bio              *master_bio;
 166         /*
 167          * if the IO is in READ direction, then this is where we read
 168          */
 169         int                     read_disk;
 170
 171         struct list_head        retry_list;
 172
 173         /*
 174          * When R1BIO_BehindIO is set, we store pages for write behind
 175          * in behind_master_bio.
 176          */
 177         struct bio              *behind_master_bio;
 178
 179         /*
 180          * if the IO is in WRITE direction, then multiple bios are used.
 181          * We choose the number when they are allocated.
 182          */
 183         struct bio              *bios[0];
 184         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 185 };
 186
 187 /* bits for r1bio.state */
 188 enum r1bio_state {
 189         R1BIO_Uptodate,
 190         R1BIO_IsSync,
 191         R1BIO_Degraded,
 192         R1BIO_BehindIO,
 193 /* Set ReadError on bios that experience a readerror so that
 194  * raid1d knows what to do with them.
 195  */
 196         R1BIO_ReadError,
 197 /* For write-behind requests, we call bi_end_io when
 198  * the last non-write-behind device completes, providing
 199  * any write was successful.  Otherwise we call when
 200  * any write-behind write succeeds, otherwise we call
 201  * with failure when last write completes (and all failed).
 202  * Record that bi_end_io was called with this flag...
 203  */
 204         R1BIO_Returned,
 205 /* If a write for this request means we can clear some
 206  * known-bad-block records, we set this flag
 207  */
 208         R1BIO_MadeGood,
 209         R1BIO_WriteError,
 210         R1BIO_FailFast,
 211 };
 212
 213 static inline int sector_to_idx(sector_t sector)
 214 {
 215         return hash_long(sector >> BARRIER_UNIT_SECTOR_BITS,
 216                          BARRIER_BUCKETS_NR_BITS);
 217 }
 218 #endif