drivers/md/raid1.h

   1 #ifndef _RAID1_H
   2 #define _RAID1_H
   3
   4 struct raid1_info {
   5         struct md_rdev  *rdev;
   6         sector_t        head_position;
   7
   8         /* When choose the best device for a read (read_balance())
   9          * we try to keep sequential reads one the same device
  10          */
  11         sector_t        next_seq_sect;
  12         sector_t        seq_start;
  13 };
  14
  15 /*
  16  * memory pools need a pointer to the mddev, so they can force an unplug
  17  * when memory is tight, and a count of the number of drives that the
  18  * pool was allocated for, so they know how much to allocate and free.
  19  * mddev->raid_disks cannot be used, as it can change while a pool is active
  20  * These two datums are stored in a kmalloced struct.
  21  * The 'raid_disks' here is twice the raid_disks in r1conf.
  22  * This allows space for each 'real' device can have a replacement in the
  23  * second half of the array.
  24  */
  25
  26 struct pool_info {
  27         struct mddev *mddev;
  28         int     raid_disks;
  29 };
  30
  31 struct r1conf {
  32         struct mddev            *mddev;
  33         struct raid1_info       *mirrors;       /* twice 'raid_disks' to
  34                                                  * allow for replacements.
  35                                                  */
  36         int                     raid_disks;
  37
  38         /* During resync, read_balancing is only allowed on the part
  39          * of the array that has been resynced.  'next_resync' tells us
  40          * where that is.
  41          */
  42         sector_t                next_resync;
  43
  44         /* When raid1 starts resync, we divide array into four partitions
  45          * |---------|--------------|---------------------|-------------|
  46          *        next_resync   start_next_window       end_window
  47          * start_next_window = next_resync + NEXT_NORMALIO_DISTANCE
  48          * end_window = start_next_window + NEXT_NORMALIO_DISTANCE
  49          * current_window_requests means the count of normalIO between
  50          *   start_next_window and end_window.
  51          * next_window_requests means the count of normalIO after end_window.
  52          * */
  53         sector_t                start_next_window;
  54         int                     current_window_requests;
  55         int                     next_window_requests;
  56
  57         spinlock_t              device_lock;
  58
  59         /* list of 'struct r1bio' that need to be processed by raid1d,
  60          * whether to retry a read, writeout a resync or recovery
  61          * block, or anything else.
  62          */
  63         struct list_head        retry_list;
  64
  65         /* queue pending writes to be submitted on unplug */
  66         struct bio_list         pending_bio_list;
  67         int                     pending_count;
  68
  69         /* for use when syncing mirrors:
  70          * We don't allow both normal IO and resync/recovery IO at
  71          * the same time - resync/recovery can only happen when there
  72          * is no other IO.  So when either is active, the other has to wait.
  73          * See more details description in raid1.c near raise_barrier().
  74          */
  75         wait_queue_head_t       wait_barrier;
  76         spinlock_t              resync_lock;
  77         int                     nr_pending;
  78         int                     nr_waiting;
  79         int                     nr_queued;
  80         int                     barrier;
  81         int                     array_frozen;
  82
  83         /* Set to 1 if a full sync is needed, (fresh device added).
  84          * Cleared when a sync completes.
  85          */
  86         int                     fullsync;
  87
  88         /* When the same as mddev->recovery_disabled we don't allow
  89          * recovery to be attempted as we expect a read error.
  90          */
  91         int                     recovery_disabled;
  92
  93         /* poolinfo contains information about the content of the
  94          * mempools - it changes when the array grows or shrinks
  95          */
  96         struct pool_info        *poolinfo;
  97         mempool_t               *r1bio_pool;
  98         mempool_t               *r1buf_pool;
  99
 100         /* temporary buffer to synchronous IO when attempting to repair
 101          * a read error.
 102          */
 103         struct page             *tmppage;
 104
 105         /* When taking over an array from a different personality, we store
 106          * the new thread here until we fully activate the array.
 107          */
 108         struct md_thread        *thread;
 109 };
 110
 111 /*
 112  * this is our 'private' RAID1 bio.
 113  *
 114  * it contains information about what kind of IO operations were started
 115  * for this RAID1 operation, and about their status:
 116  */
 117
 118 struct r1bio {
 119         atomic_t                remaining; /* 'have we finished' count,
 120                                             * used from IRQ handlers
 121                                             */
 122         atomic_t                behind_remaining; /* number of write-behind ios remaining
 123                                                  * in this BehindIO request
 124                                                  */
 125         sector_t                sector;
 126         sector_t                start_next_window;
 127         int                     sectors;
 128         unsigned long           state;
 129         struct mddev            *mddev;
 130         /*
 131          * original bio going to /dev/mdx
 132          */
 133         struct bio              *master_bio;
 134         /*
 135          * if the IO is in READ direction, then this is where we read
 136          */
 137         int                     read_disk;
 138
 139         struct list_head        retry_list;
 140         /* Next two are only valid when R1BIO_BehindIO is set */
 141         struct bio_vec          *behind_bvecs;
 142         int                     behind_page_count;
 143         /*
 144          * if the IO is in WRITE direction, then multiple bios are used.
 145          * We choose the number when they are allocated.
 146          */
 147         struct bio              *bios[0];
 148         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 149 };
 150
 151 /* bits for r1bio.state */
 152 #define R1BIO_Uptodate  0
 153 #define R1BIO_IsSync    1
 154 #define R1BIO_Degraded  2
 155 #define R1BIO_BehindIO  3
 156 /* Set ReadError on bios that experience a readerror so that
 157  * raid1d knows what to do with them.
 158  */
 159 #define R1BIO_ReadError 4
 160 /* For write-behind requests, we call bi_end_io when
 161  * the last non-write-behind device completes, providing
 162  * any write was successful.  Otherwise we call when
 163  * any write-behind write succeeds, otherwise we call
 164  * with failure when last write completes (and all failed).
 165  * Record that bi_end_io was called with this flag...
 166  */
 167 #define R1BIO_Returned 6
 168 /* If a write for this request means we can clear some
 169  * known-bad-block records, we set this flag
 170  */
 171 #define R1BIO_MadeGood 7
 172 #define R1BIO_WriteError 8
 173 #endif