lustre/kernel_patches/patches/md-avoid-bug_on-when-bmc-overflow.patch

   1 diff .prev/drivers/md/bitmap.c ./drivers/md/bitmap.c
   2 --- .prev/drivers/md/bitmap.c   2007-02-07 13:03:56.000000000 +1100
   3 +++ ./drivers/md/bitmap.c       2007-02-07 21:34:47.000000000 +1100
   4 @@ -1160,6 +1160,22 @@ int bitmap_startwrite(struct bitmap *bit
   5                         return 0;
   6                 }
   7
   8 +               if (unlikely((*bmc & COUNTER_MAX) == COUNTER_MAX)) {
   9 +                       DEFINE_WAIT(__wait);
  10 +                       /* note that it is safe to do the prepare_to_wait
  11 +                        * after the test as long as we do it before dropping
  12 +                        * the spinlock.
  13 +                        */
  14 +                       prepare_to_wait(&bitmap->overflow_wait, &__wait,
  15 +                                       TASK_UNINTERRUPTIBLE);
  16 +                       spin_unlock_irq(&bitmap->lock);
  17 +                       bitmap->mddev->queue
  18 +                               ->unplug_fn(bitmap->mddev->queue);
  19 +                       schedule();
  20 +                       finish_wait(&bitmap->overflow_wait, &__wait);
  21 +                       continue;
  22 +               }
  23 +
  24                 switch(*bmc) {
  25                 case 0:
  26                         bitmap_file_set_bit(bitmap, offset);
  27 @@ -1169,7 +1185,7 @@ int bitmap_startwrite(struct bitmap *bit
  28                 case 1:
  29                         *bmc = 2;
  30                 }
  31 -               BUG_ON((*bmc & COUNTER_MAX) == COUNTER_MAX);
  32 +
  33                 (*bmc)++;
  34
  35                 spin_unlock_irq(&bitmap->lock);
  36 @@ -1207,6 +1223,9 @@ void bitmap_endwrite(struct bitmap *bitm
  37                 if (!success && ! (*bmc & NEEDED_MASK))
  38                         *bmc |= NEEDED_MASK;
  39
  40 +               if ((*bmc & COUNTER_MAX) == COUNTER_MAX)
  41 +                       wake_up(&bitmap->overflow_wait);
  42 +
  43                 (*bmc)--;
  44                 if (*bmc <= 2) {
  45                         set_page_attr(bitmap,
  46 @@ -1431,6 +1450,7 @@ int bitmap_create(mddev_t *mddev)
  47         spin_lock_init(&bitmap->lock);
  48         atomic_set(&bitmap->pending_writes, 0);
  49         init_waitqueue_head(&bitmap->write_wait);
  50 +       init_waitqueue_head(&bitmap->overflow_wait);
  51
  52         bitmap->mddev = mddev;
  53
  54 diff .prev/include/linux/raid/bitmap.h ./include/linux/raid/bitmap.h
  55 --- .prev/include/linux/raid/bitmap.h   2007-02-07 13:03:56.000000000 +1100
  56 +++ ./include/linux/raid/bitmap.h       2007-02-07 20:57:57.000000000 +1100
  57 @@ -247,6 +247,7 @@ struct bitmap {
  58
  59         atomic_t pending_writes; /* pending writes to the bitmap file */
  60         wait_queue_head_t write_wait;
  61 +       wait_queue_head_t overflow_wait;
  62
  63  };
  64