[PATCH] md: avoid possible BUG_ON in md bitmap handling

[linux-2.6-omap-h63xx.git] / drivers / md / bitmap.c

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 11108165e26420a6f8a3eabb8794e1e0ad833754..059704fbb753ada7df4f97da979071de1cac073a 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1160,6 +1160,22 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
                        return 0;
                }
 
+               if (unlikely((*bmc & COUNTER_MAX) == COUNTER_MAX)) {
+                       DEFINE_WAIT(__wait);
+                       /* note that it is safe to do the prepare_to_wait
+                        * after the test as long as we do it before dropping
+                        * the spinlock.
+                        */
+                       prepare_to_wait(&bitmap->overflow_wait, &__wait,
+                                       TASK_UNINTERRUPTIBLE);
+                       spin_unlock_irq(&bitmap->lock);
+                       bitmap->mddev->queue
+                               ->unplug_fn(bitmap->mddev->queue);
+                       schedule();
+                       finish_wait(&bitmap->overflow_wait, &__wait);
+                       continue;
+               }
+
                switch(*bmc) {
                case 0:
                        bitmap_file_set_bit(bitmap, offset);
@@ -1169,7 +1185,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
                case 1:
                        *bmc = 2;
                }
-               BUG_ON((*bmc & COUNTER_MAX) == COUNTER_MAX);
+
                (*bmc)++;
 
                spin_unlock_irq(&bitmap->lock);
@@ -1207,6 +1223,9 @@ void bitmap_endwrite(struct bitmap *bitmap, sector_t offset, unsigned long secto
                if (!success && ! (*bmc & NEEDED_MASK))
                        *bmc |= NEEDED_MASK;
 
+               if ((*bmc & COUNTER_MAX) == COUNTER_MAX)
+                       wake_up(&bitmap->overflow_wait);
+
                (*bmc)--;
                if (*bmc <= 2) {
                        set_page_attr(bitmap,
@@ -1431,6 +1450,7 @@ int bitmap_create(mddev_t *mddev)
        spin_lock_init(&bitmap->lock);
        atomic_set(&bitmap->pending_writes, 0);
        init_waitqueue_head(&bitmap->write_wait);
+       init_waitqueue_head(&bitmap->overflow_wait);
 
        bitmap->mddev = mddev;