drivers/md/raid1.h

   1 #ifndef _RAID1_H
   2 #define _RAID1_H
   3
   4 struct mirror_info {
   5         struct md_rdev  *rdev;
   6         sector_t        head_position;
   7 };
   8
   9 /*
  10  * memory pools need a pointer to the mddev, so they can force an unplug
  11  * when memory is tight, and a count of the number of drives that the
  12  * pool was allocated for, so they know how much to allocate and free.
  13  * mddev->raid_disks cannot be used, as it can change while a pool is active
  14  * These two datums are stored in a kmalloced struct.
  15  * The 'raid_disks' here is twice the raid_disks in r1conf.
  16  * This allows space for each 'real' device can have a replacement in the
  17  * second half of the array.
  18  */
  19
  20 struct pool_info {
  21         struct mddev *mddev;
  22         int     raid_disks;
  23 };
  24
  25 struct r1conf {
  26         struct mddev            *mddev;
  27         struct mirror_info      *mirrors;       /* twice 'raid_disks' to
  28                                                  * allow for replacements.
  29                                                  */
  30         int                     raid_disks;
  31
  32         /* When choose the best device for a read (read_balance())
  33          * we try to keep sequential reads one the same device
  34          * using 'last_used' and 'next_seq_sect'
  35          */
  36         int                     last_used;
  37         sector_t                next_seq_sect;
  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         spinlock_t              device_lock;
  45
  46         /* list of 'struct r1bio' that need to be processed by raid1d,
  47          * whether to retry a read, writeout a resync or recovery
  48          * block, or anything else.
  49          */
  50         struct list_head        retry_list;
  51
  52         /* queue pending writes to be submitted on unplug */
  53         struct bio_list         pending_bio_list;
  54         int                     pending_count;
  55
  56         /* for use when syncing mirrors:
  57          * We don't allow both normal IO and resync/recovery IO at
  58          * the same time - resync/recovery can only happen when there
  59          * is no other IO.  So when either is active, the other has to wait.
  60          * See more details description in raid1.c near raise_barrier().
  61          */
  62         wait_queue_head_t       wait_barrier;
  63         spinlock_t              resync_lock;
  64         int                     nr_pending;
  65         int                     nr_waiting;
  66         int                     nr_queued;
  67         int                     barrier;
  68
  69         /* Set to 1 if a full sync is needed, (fresh device added).
  70          * Cleared when a sync completes.
  71          */
  72         int                     fullsync;
  73
  74         /* When the same as mddev->recovery_disabled we don't allow
  75          * recovery to be attempted as we expect a read error.
  76          */
  77         int                     recovery_disabled;
  78
  79
  80         /* poolinfo contains information about the content of the
  81          * mempools - it changes when the array grows or shrinks
  82          */
  83         struct pool_info        *poolinfo;
  84         mempool_t               *r1bio_pool;
  85         mempool_t               *r1buf_pool;
  86
  87         /* temporary buffer to synchronous IO when attempting to repair
  88          * a read error.
  89          */
  90         struct page             *tmppage;
  91
  92
  93         /* When taking over an array from a different personality, we store
  94          * the new thread here until we fully activate the array.
  95          */
  96         struct md_thread        *thread;
  97 };
  98
  99 /*
 100  * this is our 'private' RAID1 bio.
 101  *
 102  * it contains information about what kind of IO operations were started
 103  * for this RAID1 operation, and about their status:
 104  */
 105
 106 struct r1bio {
 107         atomic_t                remaining; /* 'have we finished' count,
 108                                             * used from IRQ handlers
 109                                             */
 110         atomic_t                behind_remaining; /* number of write-behind ios remaining
 111                                                  * in this BehindIO request
 112                                                  */
 113         sector_t                sector;
 114         int                     sectors;
 115         unsigned long           state;
 116         struct mddev            *mddev;
 117         /*
 118          * original bio going to /dev/mdx
 119          */
 120         struct bio              *master_bio;
 121         /*
 122          * if the IO is in READ direction, then this is where we read
 123          */
 124         int                     read_disk;
 125
 126         struct list_head        retry_list;
 127         /* Next two are only valid when R1BIO_BehindIO is set */
 128         struct bio_vec          *behind_bvecs;
 129         int                     behind_page_count;
 130         /*
 131          * if the IO is in WRITE direction, then multiple bios are used.
 132          * We choose the number when they are allocated.
 133          */
 134         struct bio              *bios[0];
 135         /* DO NOT PUT ANY NEW FIELDS HERE - bios array is contiguously alloced*/
 136 };
 137
 138 /* when we get a read error on a read-only array, we redirect to another
 139  * device without failing the first device, or trying to over-write to
 140  * correct the read error.  To keep track of bad blocks on a per-bio
 141  * level, we store IO_BLOCKED in the appropriate 'bios' pointer
 142  */
 143 #define IO_BLOCKED ((struct bio *)1)
 144 /* When we successfully write to a known bad-block, we need to remove the
 145  * bad-block marking which must be done from process context.  So we record
 146  * the success by setting bios[n] to IO_MADE_GOOD
 147  */
 148 #define IO_MADE_GOOD ((struct bio *)2)
 149
 150 #define BIO_SPECIAL(bio) ((unsigned long)bio <= 2)
 151
 152 /* bits for r1bio.state */
 153 #define R1BIO_Uptodate  0
 154 #define R1BIO_IsSync    1
 155 #define R1BIO_Degraded  2
 156 #define R1BIO_BehindIO  3
 157 /* Set ReadError on bios that experience a readerror so that
 158  * raid1d knows what to do with them.
 159  */
 160 #define R1BIO_ReadError 4
 161 /* For write-behind requests, we call bi_end_io when
 162  * the last non-write-behind device completes, providing
 163  * any write was successful.  Otherwise we call when
 164  * any write-behind write succeeds, otherwise we call
 165  * with failure when last write completes (and all failed).
 166  * Record that bi_end_io was called with this flag...
 167  */
 168 #define R1BIO_Returned 6
 169 /* If a write for this request means we can clear some
 170  * known-bad-block records, we set this flag
 171  */
 172 #define R1BIO_MadeGood 7
 173 #define R1BIO_WriteError 8
 174
 175 extern int md_raid1_congested(struct mddev *mddev, int bits);
 176
 177 #endif