lustre/kernel_patches/patches/raid6-stripe-by-stripe-handling.patch

   1 diff -pur linux-2.6.9.orig/drivers/md/raid6main.c linux-2.6.9/drivers/md/raid6main.c
   2 --- linux-2.6.9.orig/drivers/md/raid6main.c     2008-01-10 13:47:18.000000000 +0800
   3 +++ linux-2.6.9/drivers/md/raid6main.c  2008-01-10 13:49:06.000000000 +0800
   4 @@ -1571,6 +1571,11 @@ static int make_request (request_queue_t
   5         sector_t new_sector;
   6         sector_t logical_sector, last_sector;
   7         struct stripe_head *sh;
   8 +       sector_t stripe, sectors, block, r_sector, b_sector;
   9 +       int sectors_per_chunk;
  10 +       int stripes_per_chunk, sectors_per_block;
  11 +       int sectors_per_stripe;
  12 +       int i, j;
  13
  14         atomic_inc(&conf->in_reqs_in_queue);
  15
  16 @@ -1596,30 +1601,69 @@ static int make_request (request_queue_t
  17         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
  18         if ( bio_data_dir(bi) == WRITE )
  19                 md_write_start(mddev);
  20 -       for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
  21
  22 -               new_sector = raid6_compute_sector(logical_sector,
  23 -                                                 raid_disks, data_disks, &dd_idx, &pd_idx, conf);
  24 -
  25 -               PRINTK("raid6: make_request, sector %Lu logical %Lu\n",
  26 -                      (unsigned long long)new_sector,
  27 -                      (unsigned long long)logical_sector);
  28 +       sectors_per_chunk = conf->chunk_size >> 9;
  29 +       stripes_per_chunk = conf->chunk_size / STRIPE_SIZE;
  30 +       sectors_per_stripe = STRIPE_SECTORS * data_disks;
  31 +       sectors_per_block = stripes_per_chunk * sectors_per_stripe;
  32 +
  33 +       block = logical_sector & ~((sector_t)sectors_per_block - 1);
  34 +       sector_div(block, sectors_per_block);
  35 +       sectors = bi->bi_size >> 9;
  36 +
  37 + repeat:
  38 +       stripe = block * (sectors_per_block / data_disks);
  39 +       b_sector = stripe * data_disks;
  40 +       /* iterate through all stripes in this block,
  41 +        * where block is a set of internal stripes
  42 +        * which covers chunk */
  43 +       for (i = 0; i < stripes_per_chunk && sectors > 0; i++) {
  44 +               r_sector = b_sector + (i * STRIPE_SECTORS);
  45 +               sh = NULL;
  46 +               /* iterrate through all pages in the stripe */
  47 +               for (j = 0; j < data_disks && sectors > 0; j++) {
  48 +                       if (r_sector + STRIPE_SECTORS <= bi->bi_sector ||
  49 +                           r_sector >= last_sector) {
  50 +                               r_sector += sectors_per_chunk;
  51 +                               continue;
  52 +                       }
  53 +                       new_sector = raid6_compute_sector(r_sector, raid_disks,
  54 +                                                       data_disks, &dd_idx,
  55 +                                                       &pd_idx, conf);
  56 +                       if (sh == NULL)
  57 +                               sh = get_active_stripe(conf, new_sector, pd_idx,
  58 +                                                       (bi->bi_rw&RWA_MASK));
  59 +                       if (sh) {
  60 +                               add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK));
  61 +                       } else {
  62 +                               /* cannot get stripe for read-ahead, just give-up */
  63 +                               clear_bit(BIO_UPTODATE, &bi->bi_flags);
  64 +                               sectors = 0;
  65 +                               break;
  66 +                       }
  67 +
  68 +                       BUG_ON (new_sector != stripe);
  69 +                       sectors -= STRIPE_SECTORS;
  70 +                       if (bi->bi_sector > r_sector)
  71 +                               sectors += bi->bi_sector - r_sector;
  72 +                       if (r_sector + STRIPE_SECTORS > last_sector)
  73 +                               sectors += r_sector + STRIPE_SECTORS - last_sector;
  74 +                       r_sector += sectors_per_chunk;
  75 +               }
  76
  77 -               sh = get_active_stripe(conf, new_sector, pd_idx, (bi->bi_rw&RWA_MASK));
  78                 if (sh) {
  79 -
  80 -                       add_stripe_bio(sh, bi, dd_idx, (bi->bi_rw&RW_MASK));
  81 -
  82                         raid6_plug_device(conf);
  83                         handle_stripe(sh);
  84                         release_stripe(sh);
  85 -               } else {
  86 -                       /* cannot get stripe for read-ahead, just give-up */
  87 -                       clear_bit(BIO_UPTODATE, &bi->bi_flags);
  88 -                       break;
  89 +                       sh = NULL;
  90                 }
  91
  92 +               stripe += STRIPE_SECTORS;
  93         }
  94 +       block++;
  95 +       if(sectors > 0)
  96 +               goto repeat;
  97 +
  98         spin_lock_irq(&conf->device_lock);
  99         if (--bi->bi_phys_segments == 0) {
 100                 int bytes = bi->bi_size;