bcache: Stripe size isn't necessarily a power of two

Originally I got this right... except that the divides didn't use
do_div(), which broke 32 bit kernels. When I went to fix that, I forgot
that the raid stripe size usually isn't a power of two... doh

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

1 files changed, 5 insertions, 3 deletions

diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h
index c91f61bb95b6..34961888b5a9 100644
--- a/drivers/md/bcache/writeback.h
+++ b/drivers/md/bcache/writeback.h
@@ -18,16 +18,18 @@ static inline bool bcache_dev_stripe_dirty(struct bcache_device *d,
                                            uint64_t offset,
                                            unsigned nr_sectors)
 {
-        uint64_t stripe = offset >> d->stripe_size_bits;
+        uint64_t stripe = offset;
+
+        do_div(stripe, d->stripe_size);
 
         while (1) {
                 if (atomic_read(d->stripe_sectors_dirty + stripe))
                         return true;
 
-                if (nr_sectors <= 1 << d->stripe_size_bits)
+                if (nr_sectors <= d->stripe_size)
                         return false;
 
-                nr_sectors -= 1 << d->stripe_size_bits;
+                nr_sectors -= d->stripe_size;
                 stripe++;
         }
 }