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 };
  13
  14 /*
  15  * memory pools need a pointer to the mddev, so they can force an unplug
  16  * when memory is tight, and a count of the number of drives that the
  17  * pool was allocated for, so they know how much to allocate and free.
  18  * mddev->raid_disks cannot be used, as it can change while a pool is active
  19  * These two datums are stored in a kmalloced struct.
  20  * The 'raid_disks' here is twice the raid_disks in r1conf.
  21  * This allows space for each 'real' device can have a replacement in the
  22  * second half of the array.
  23  */
  24
  25 struct pool_info {
  26         struct mddev *mddev;
  27         int     raid_disks;
  28 };
  29
  30 struct r1conf {
  31         struct mddev            *mddev;
  32         struct raid1_info       *mirrors;       /* twice 'raid_disks' to
  33                                                  * allow for replacements.
  34                                                  */
  35         int                     raid_disks;
  36
  37         /* During resync, read_balancing is only allowed on the part
  38          * of the array that has been resynced.  'next_resync' tells us
  39          * where that is.
  40          */
  41         sector_t                next_resync;
  42
  43         spinlock_t              device_lock;
  44
  45         /* list of 'struct r1bio' that need to be processed by raid1d,
  46          * whether to retry a read, writeout a resync or recovery
  47          * block, or anything else.
  48          */
  49         struct list_head        retry_list;
  50
  51         /* queue pending writes to be submitted on unplug */
  52         struct bio_list         pending_bio_list;
  53         int                     pending_count;
  54
  55         /* for use when syncing mirrors:
  56          * We don't allow both normal IO and resync/recovery IO at
  57          * the same time - resync/recovery can only happen when there
  58          * is no other IO.  So when either is active, the other has to wait.
  59          * See more details description in raid1.c near raise_barrier().
  60          */
  61         wait_queue_head_t       wait_barrier;
  62         spinlock_t              resync_lock;
  63         int                     nr_pending;
  64         int                     nr_waiting;
  65         int                     nr_queued;
  66         int                     barrier;
  67
  68         /* Set to 1 if a full sync is needed, (fresh device added).
  69          * Cleared when a sync completes.
  70          */
  71         int                     fullsync;
  72
  73         /* When the same as mddev->recovery_disabled we don't allow
  74          * recovery to be attempted as we expect a read error.
  75          */
  76         int                     recovery_disabled;
  77
  78
  79         /* poolinfo contains information about the content of the
  80          * mempools - it changes when the array grows or shrinks
  81          */
  82         struct pool_info        *poolinfo;
  83         mempool_t               *r1bio_pool;
  84         mempool_t               *r1buf_pool;
  85
  86         /* temporary buffer to synchronous IO when attempting to repair
  87          * a read error.
  88          */
  89         struct page             *tmppage;
  90
  91
  92         /* When taking over an array from a different personality, we store
  93          * the new thread here until we fully activate the array.
  94          */
  95         struct md_thread        *thread;
  96 };
  97
  98 /*
  99  * this is our 'private' RAID1 bio.
 100  *
 101  * it contains information about what kind of IO operations were started
 102  * for this RAID1 operation, and about their status:
 103  */
 104
 105 struct r1bio {
 106         atomic_t                remaining; /* 'have we finished' count,
 107                                             * used from IRQ handlers
 108                                             */
 109         atomic_t                behind_remaining; /* number of write-behind ios remaining
 110                                                  * in this BehindIO request
 111                                                  */
 112         sector_t                sector;
 113         int                     sectors;
 114         unsigned long           state;
 115         struct mddev            *mddev;
 116         /*
 117          * original bio going to /dev/mdx
 118          */
 119         struct bio              *master_bio;
 120         /*
 121          * if the IO is in READ direction, then this is where we read
 122          */
 123         int                     read_disk;
 124
 125         struct list_head        retry_list;
 126         /* Next two are only valid when R1BIO_BehindIO is set */
 127         struct bio_vec          *behind_bvecs;
 128         int                     behind_page_count;
 129         /*
 130          * if the IO is in WRITE direction, then multiple bios are used.
 131          * We choose the number when they are allocated.
 132          */
 133         struct bio              *bios[0];
 134         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 135 };
 136
 137 /* bits for r1bio.state */
 138 #define R1BIO_Uptodate  0
 139 #define R1BIO_IsSync    1
 140 #define R1BIO_Degraded  2
 141 #define R1BIO_BehindIO  3
 142 /* Set ReadError on bios that experience a readerror so that
 143  * raid1d knows what to do with them.
 144  */
 145 #define R1BIO_ReadError 4
 146 /* For write-behind requests, we call bi_end_io when
 147  * the last non-write-behind device completes, providing
 148  * any write was successful.  Otherwise we call when
 149  * any write-behind write succeeds, otherwise we call
 150  * with failure when last write completes (and all failed).
 151  * Record that bi_end_io was called with this flag...
 152  */
 153 #define R1BIO_Returned 6
 154 /* If a write for this request means we can clear some
 155  * known-bad-block records, we set this flag
 156  */
 157 #define R1BIO_MadeGood 7
 158 #define R1BIO_WriteError 8
 159
 160 extern int md_raid1_congested(struct mddev *mddev, int bits);
 161
 162 #endif