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         /* A separate list of r1bio which just need raid_end_bio_io called.
  65          * This mustn't happen for writes which had any errors if the superblock
  66          * needs to be written.
  67          */
  68         struct list_head        bio_end_io_list;
  69
  70         /* queue pending writes to be submitted on unplug */
  71         struct bio_list         pending_bio_list;
  72         int                     pending_count;
  73
  74         /* for use when syncing mirrors:
  75          * We don't allow both normal IO and resync/recovery IO at
  76          * the same time - resync/recovery can only happen when there
  77          * is no other IO.  So when either is active, the other has to wait.
  78          * See more details description in raid1.c near raise_barrier().
  79          */
  80         wait_queue_head_t       wait_barrier;
  81         spinlock_t              resync_lock;
  82         int                     nr_pending;
  83         int                     nr_waiting;
  84         int                     nr_queued;
  85         int                     barrier;
  86         int                     array_frozen;
  87
  88         /* Set to 1 if a full sync is needed, (fresh device added).
  89          * Cleared when a sync completes.
  90          */
  91         int                     fullsync;
  92
  93         /* When the same as mddev->recovery_disabled we don't allow
  94          * recovery to be attempted as we expect a read error.
  95          */
  96         int                     recovery_disabled;
  97
  98         /* poolinfo contains information about the content of the
  99          * mempools - it changes when the array grows or shrinks
 100          */
 101         struct pool_info        *poolinfo;
 102         mempool_t               *r1bio_pool;
 103         mempool_t               *r1buf_pool;
 104
 105         /* temporary buffer to synchronous IO when attempting to repair
 106          * a read error.
 107          */
 108         struct page             *tmppage;
 109
 110         /* When taking over an array from a different personality, we store
 111          * the new thread here until we fully activate the array.
 112          */
 113         struct md_thread        *thread;
 114 };
 115
 116 /*
 117  * this is our 'private' RAID1 bio.
 118  *
 119  * it contains information about what kind of IO operations were started
 120  * for this RAID1 operation, and about their status:
 121  */
 122
 123 struct r1bio {
 124         atomic_t                remaining; /* 'have we finished' count,
 125                                             * used from IRQ handlers
 126                                             */
 127         atomic_t                behind_remaining; /* number of write-behind ios remaining
 128                                                  * in this BehindIO request
 129                                                  */
 130         sector_t                sector;
 131         sector_t                start_next_window;
 132         int                     sectors;
 133         unsigned long           state;
 134         struct mddev            *mddev;
 135         /*
 136          * original bio going to /dev/mdx
 137          */
 138         struct bio              *master_bio;
 139         /*
 140          * if the IO is in READ direction, then this is where we read
 141          */
 142         int                     read_disk;
 143
 144         struct list_head        retry_list;
 145         /* Next two are only valid when R1BIO_BehindIO is set */
 146         struct bio_vec          *behind_bvecs;
 147         int                     behind_page_count;
 148         /*
 149          * if the IO is in WRITE direction, then multiple bios are used.
 150          * We choose the number when they are allocated.
 151          */
 152         struct bio              *bios[0];
 153         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 154 };
 155
 156 /* bits for r1bio.state */
 157 #define R1BIO_Uptodate  0
 158 #define R1BIO_IsSync    1
 159 #define R1BIO_Degraded  2
 160 #define R1BIO_BehindIO  3
 161 /* Set ReadError on bios that experience a readerror so that
 162  * raid1d knows what to do with them.
 163  */
 164 #define R1BIO_ReadError 4
 165 /* For write-behind requests, we call bi_end_io when
 166  * the last non-write-behind device completes, providing
 167  * any write was successful.  Otherwise we call when
 168  * any write-behind write succeeds, otherwise we call
 169  * with failure when last write completes (and all failed).
 170  * Record that bi_end_io was called with this flag...
 171  */
 172 #define R1BIO_Returned 6
 173 /* If a write for this request means we can clear some
 174  * known-bad-block records, we set this flag
 175  */
 176 #define R1BIO_MadeGood 7
 177 #define R1BIO_WriteError 8
 178 #endif