Merge branch 'for-linus' of git://git.kernel.dk/linux-2.6-block

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  cdrom: support devices that have check_events but not media_changed
  cfq-iosched: Don't wait if queue already has requests.
  blkio-throttle: Avoid calling blkiocg_lookup_group() for root group
  cfq: rename a function to give it more appropriate name
  cciss: make cciss_revalidate not loop through CISS_MAX_LUNS volumes unnecessarily.
  drivers/block/aoe/Makefile: replace the use of <module>-objs with <module>-y
  loop: queue_lock NULL pointer derefence in blk_throtl_exit
  drivers/block/Makefile: replace the use of <module>-objs with <module>-y
  blktrace: Don't output messages if NOTIFY isn't set.

2 files changed, 16 insertions, 4 deletions

diff --git a/block/blk-throttle.c b/block/blk-throttle.c
index 381b09bb562b..a89043a3caa4 100644
--- a/block/blk-throttle.c
+++ b/block/blk-throttle.c
@@ -168,7 +168,15 @@ static struct throtl_grp * throtl_find_alloc_tg(struct throtl_data *td,
          * tree of blkg (instead of traversing through hash list all
          * the time.
          */
-        tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
+
+        /*
+         * This is the common case when there are no blkio cgroups.
+         * Avoid lookup in this case
+         */
+        if (blkcg == &blkio_root_cgroup)
+                tg = &td->root_tg;
+        else
+                tg = tg_of_blkg(blkiocg_lookup_group(blkcg, key));
 
         /* Fill in device details for root group */
         if (tg && !tg->blkg.dev && bdi->dev && dev_name(bdi->dev)) {
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 501ffdf0399c..7be4c7959625 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -599,7 +599,7 @@ cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg)
 }
 
 static inline unsigned
-cfq_scaled_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
+cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
         unsigned slice = cfq_prio_to_slice(cfqd, cfqq);
         if (cfqd->cfq_latency) {
@@ -631,7 +631,7 @@ cfq_scaled_group_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 static inline void
 cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
-        unsigned slice = cfq_scaled_group_slice(cfqd, cfqq);
+        unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq);
 
         cfqq->slice_start = jiffies;
         cfqq->slice_end = jiffies + slice;
@@ -1671,7 +1671,7 @@ __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq,
          */
         if (timed_out) {
                 if (cfq_cfqq_slice_new(cfqq))
-                        cfqq->slice_resid = cfq_scaled_group_slice(cfqd, cfqq);
+                        cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq);
                 else
                         cfqq->slice_resid = cfqq->slice_end - jiffies;
                 cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid);
@@ -3432,6 +3432,10 @@ static bool cfq_should_wait_busy(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
         struct cfq_io_context *cic = cfqd->active_cic;
 
+        /* If the queue already has requests, don't wait */
+        if (!RB_EMPTY_ROOT(&cfqq->sort_list))
+                return false;
+
         /* If there are other queues in the group, don't wait */
         if (cfqq->cfqg->nr_cfqq > 1)
                 return false;