bcache/md: Use raid stripe size

Now that we've got code for raid5/6 stripe awareness, bcache just needs
to know about the stripes and when writing partial stripes is expensive
- we probably don't want to enable this optimization for raid1 or 10,
even though they have stripes. So add a flag to queue_limits.

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

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 63ebef78df4a..e363efcf2b76 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1134,6 +1134,12 @@ static int cached_dev_init(struct cached_dev *dc, unsigned block_size)
                 hlist_add_head(&io->hash, dc->io_hash + RECENT_IO);
         }
 
+        dc->disk.stripe_size = q->limits.io_opt >> 9;
+
+        if (dc->disk.stripe_size)
+                dc->partial_stripes_expensive =
+                        q->limits.raid_partial_stripes_expensive;
+
         ret = bcache_device_init(&dc->disk, block_size,
                          dc->bdev->bd_part->nr_sects - dc->sb.data_offset);
         if (ret)