cfq-iosched: Fix update_vdisktime logic

The update_vdisktime logic is broken since commit
b54ce60eb7f61f8e314b8b241b0469eda3bb1d42, st->min_vdisktime never makes
a progress. Fix it.

Thanks Vivek for pointing it out.

Signed-off-by: Gui Jianfeng <guijianfen@cn.fujitsu.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 135b1a4..938ae52 100644 (file)
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -557,15 +557,13 @@ static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime)
 
 static void update_min_vdisktime(struct cfq_rb_root *st)
 {
-       u64 vdisktime = st->min_vdisktime;
        struct cfq_group *cfqg;
 
        if (st->left) {
                cfqg = rb_entry_cfqg(st->left);
-               vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
+               st->min_vdisktime = max_vdisktime(st->min_vdisktime,
+                                                 cfqg->vdisktime);
        }
-
-       st->min_vdisktime = max_vdisktime(st->min_vdisktime, vdisktime);
 }
 
 /*