[PATCH] bcache: let the writeback thread run at least once at startup

["Darrick J. Wong" <darrick.wong@oracle.com>]

Change bch_cached_dev_attach() to always wake up the writeback thread,
because the newly created wb thread remains in uninterruptible sleep
state until something explicitly wakes it up.  This wakeup allows the
thread to call bch_writeback_thread(), whereupon it will most likely
end up in interruptible sleep.  In theory we could just let the first
write take care of this, but there's really no reason not to do the
transition quickly.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 drivers/md/bcache/super.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 24a3a15..3ffe970 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -1048,8 +1048,8 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
 		bch_sectors_dirty_init(dc);
 		atomic_set(&dc->has_dirty, 1);
 		atomic_inc(&dc->count);
-		bch_writeback_queue(dc);
 	}
+	bch_writeback_queue(dc);
 
 	bch_cached_dev_run(dc);
 	bcache_device_link(&dc->disk, c, "bdev");