3 files changed, 156 insertions, 35 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index f84cce42fc58..f0640d7f800f 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1149,13 +1149,10 @@ void init_request_from_bio(struct request *req, struct bio *bio)
         else
                 req->cmd_flags |= bio->bi_rw & REQ_FAILFAST_MASK;
 
-        if (unlikely(bio_rw_flagged(bio, BIO_RW_DISCARD))) {
+        if (bio_rw_flagged(bio, BIO_RW_DISCARD))
                 req->cmd_flags |= REQ_DISCARD;
-                if (bio_rw_flagged(bio, BIO_RW_BARRIER))
-                        req->cmd_flags |= REQ_SOFTBARRIER;
-        } else if (unlikely(bio_rw_flagged(bio, BIO_RW_BARRIER)))
+        if (bio_rw_flagged(bio, BIO_RW_BARRIER))
                 req->cmd_flags |= REQ_HARDBARRIER;
-
         if (bio_rw_flagged(bio, BIO_RW_SYNCIO))
                 req->cmd_flags |= REQ_RW_SYNC;
         if (bio_rw_flagged(bio, BIO_RW_META))
@@ -1586,7 +1583,7 @@ void submit_bio(int rw, struct bio *bio)
          * If it's a regular read/write or a barrier with data attached,
          * go through the normal accounting stuff before submission.
          */
-        if (bio_has_data(bio)) {
+        if (bio_has_data(bio) && !(rw & (1 << BIO_RW_DISCARD))) {
                 if (rw & WRITE) {
                         count_vm_events(PGPGOUT, count);
                 } else {
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 5ff4f4850e71..7982b830db58 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -14,7 +14,7 @@
 #include <linux/rbtree.h>
 #include <linux/ioprio.h>
 #include <linux/blktrace_api.h>
-#include "blk-cgroup.h"
+#include "cfq.h"
 
 /*
  * tunables
@@ -879,7 +879,7 @@ cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
         if (!RB_EMPTY_NODE(&cfqg->rb_node))
                 cfq_rb_erase(&cfqg->rb_node, st);
         cfqg->saved_workload_slice = 0;
-        blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
+        cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1);
 }
 
 static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
@@ -939,8 +939,8 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
 
         cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime,
                                         st->min_vdisktime);
-        blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
-        blkiocg_set_start_empty_time(&cfqg->blkg);
+        cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
+        cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
 }
 
 #ifdef CONFIG_CFQ_GROUP_IOSCHED
@@ -995,7 +995,7 @@ cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
 
         /* Add group onto cgroup list */
         sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
-        blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
+        cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
                                         MKDEV(major, minor));
         cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev);
 
@@ -1079,7 +1079,7 @@ static void cfq_release_cfq_groups(struct cfq_data *cfqd)
                  * it from cgroup list, then it will take care of destroying
                  * cfqg also.
                  */
-                if (!blkiocg_del_blkio_group(&cfqg->blkg))
+                if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg))
                         cfq_destroy_cfqg(cfqd, cfqg);
         }
 }
@@ -1421,10 +1421,10 @@ static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq)
 {
         elv_rb_del(&cfqq->sort_list, rq);
         cfqq->queued[rq_is_sync(rq)]--;
-        blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq),
-                                                rq_is_sync(rq));
+        cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
+                                        rq_data_dir(rq), rq_is_sync(rq));
         cfq_add_rq_rb(rq);
-        blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
+        cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
                         &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq),
                         rq_is_sync(rq));
 }
@@ -1482,8 +1482,8 @@ static void cfq_remove_request(struct request *rq)
         cfq_del_rq_rb(rq);
 
         cfqq->cfqd->rq_queued--;
-        blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(rq),
-                                                rq_is_sync(rq));
+        cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
+                                        rq_data_dir(rq), rq_is_sync(rq));
         if (rq_is_meta(rq)) {
                 WARN_ON(!cfqq->meta_pending);
                 cfqq->meta_pending--;
@@ -1518,8 +1518,8 @@ static void cfq_merged_request(struct request_queue *q, struct request *req,
 static void cfq_bio_merged(struct request_queue *q, struct request *req,
                                 struct bio *bio)
 {
-        blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, bio_data_dir(bio),
-                                        cfq_bio_sync(bio));
+        cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg,
+                                        bio_data_dir(bio), cfq_bio_sync(bio));
 }
 
 static void
@@ -1539,8 +1539,8 @@ cfq_merged_requests(struct request_queue *q, struct request *rq,
         if (cfqq->next_rq == next)
                 cfqq->next_rq = rq;
         cfq_remove_request(next);
-        blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, rq_data_dir(next),
-                                        rq_is_sync(next));
+        cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg,
+                                        rq_data_dir(next), rq_is_sync(next));
 }
 
 static int cfq_allow_merge(struct request_queue *q, struct request *rq,
@@ -1571,7 +1571,7 @@ static int cfq_allow_merge(struct request_queue *q, struct request *rq,
 static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 {
         del_timer(&cfqd->idle_slice_timer);
-        blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
+        cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg);
 }
 
 static void __cfq_set_active_queue(struct cfq_data *cfqd,
@@ -1580,7 +1580,7 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
         if (cfqq) {
                 cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d",
                                 cfqd->serving_prio, cfqd->serving_type);
-                blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
+                cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg);
                 cfqq->slice_start = 0;
                 cfqq->dispatch_start = jiffies;
                 cfqq->allocated_slice = 0;
@@ -1911,7 +1911,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
         sl = cfqd->cfq_slice_idle;
 
         mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
-        blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
+        cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
         cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
 }
 
@@ -1931,7 +1931,7 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
         elv_dispatch_sort(q, rq);
 
         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
-        blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
+        cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
                                         rq_data_dir(rq), rq_is_sync(rq));
 }
 
@@ -1986,6 +1986,15 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
         int process_refs, new_process_refs;
         struct cfq_queue *__cfqq;
 
+        /*
+         * If there are no process references on the new_cfqq, then it is
+         * unsafe to follow the ->new_cfqq chain as other cfqq's in the
+         * chain may have dropped their last reference (not just their
+         * last process reference).
+         */
+        if (!cfqq_process_refs(new_cfqq))
+                return;
+
         /* Avoid a circular list and skip interim queue merges */
         while ((__cfqq = new_cfqq->new_cfqq)) {
                 if (__cfqq == cfqq)
@@ -1994,17 +2003,17 @@ static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq)
         }
 
         process_refs = cfqq_process_refs(cfqq);
+        new_process_refs = cfqq_process_refs(new_cfqq);
         /*
          * If the process for the cfqq has gone away, there is no
          * sense in merging the queues.
          */
-        if (process_refs == 0)
+        if (process_refs == 0 || new_process_refs == 0)
                 return;
 
         /*
          * Merge in the direction of the lesser amount of work.
          */
-        new_process_refs = cfqq_process_refs(new_cfqq);
         if (new_process_refs >= process_refs) {
                 cfqq->new_cfqq = new_cfqq;
                 atomic_add(process_refs, &new_cfqq->ref);
@@ -3248,7 +3257,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
                                 cfq_clear_cfqq_wait_request(cfqq);
                                 __blk_run_queue(cfqd->queue);
                         } else {
-                                blkiocg_update_idle_time_stats(
+                                cfq_blkiocg_update_idle_time_stats(
                                                 &cfqq->cfqg->blkg);
                                 cfq_mark_cfqq_must_dispatch(cfqq);
                         }
@@ -3276,7 +3285,7 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
         rq_set_fifo_time(rq, jiffies + cfqd->cfq_fifo_expire[rq_is_sync(rq)]);
         list_add_tail(&rq->queuelist, &cfqq->fifo);
         cfq_add_rq_rb(rq);
-        blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
+        cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg,
                         &cfqd->serving_group->blkg, rq_data_dir(rq),
                         rq_is_sync(rq));
         cfq_rq_enqueued(cfqd, cfqq, rq);
@@ -3364,9 +3373,9 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
         WARN_ON(!cfqq->dispatched);
         cfqd->rq_in_driver--;
         cfqq->dispatched--;
-        blkiocg_update_completion_stats(&cfqq->cfqg->blkg, rq_start_time_ns(rq),
-                        rq_io_start_time_ns(rq), rq_data_dir(rq),
-                        rq_is_sync(rq));
+        cfq_blkiocg_update_completion_stats(&cfqq->cfqg->blkg,
+                        rq_start_time_ns(rq), rq_io_start_time_ns(rq),
+                        rq_data_dir(rq), rq_is_sync(rq));
 
         cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]--;
 
@@ -3730,7 +3739,7 @@ static void cfq_exit_queue(struct elevator_queue *e)
 
         cfq_put_async_queues(cfqd);
         cfq_release_cfq_groups(cfqd);
-        blkiocg_del_blkio_group(&cfqd->root_group.blkg);
+        cfq_blkiocg_del_blkio_group(&cfqd->root_group.blkg);
 
         spin_unlock_irq(q->queue_lock);
 
@@ -3798,8 +3807,8 @@ static void *cfq_init_queue(struct request_queue *q)
          */
         atomic_set(&cfqg->ref, 1);
         rcu_read_lock();
-        blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg, (void *)cfqd,
-                                        0);
+        cfq_blkiocg_add_blkio_group(&blkio_root_cgroup, &cfqg->blkg,
+                                        (void *)cfqd, 0);
         rcu_read_unlock();
 #endif
         /*
diff --git a/block/cfq.h b/block/cfq.h
new file mode 100644
index 000000000000..93448e5a2e41
--- /dev/null
+++ b/block/cfq.h
@@ -0,0 +1,115 @@
+#ifndef _CFQ_H
+#define _CFQ_H
+#include "blk-cgroup.h"
+
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+static inline void cfq_blkiocg_update_io_add_stats(struct blkio_group *blkg,
+        struct blkio_group *curr_blkg, bool direction, bool sync)
+{
+        blkiocg_update_io_add_stats(blkg, curr_blkg, direction, sync);
+}
+
+static inline void cfq_blkiocg_update_dequeue_stats(struct blkio_group *blkg,
+                        unsigned long dequeue)
+{
+        blkiocg_update_dequeue_stats(blkg, dequeue);
+}
+
+static inline void cfq_blkiocg_update_timeslice_used(struct blkio_group *blkg,
+                        unsigned long time)
+{
+        blkiocg_update_timeslice_used(blkg, time);
+}
+
+static inline void cfq_blkiocg_set_start_empty_time(struct blkio_group *blkg)
+{
+        blkiocg_set_start_empty_time(blkg);
+}
+
+static inline void cfq_blkiocg_update_io_remove_stats(struct blkio_group *blkg,
+                                bool direction, bool sync)
+{
+        blkiocg_update_io_remove_stats(blkg, direction, sync);
+}
+
+static inline void cfq_blkiocg_update_io_merged_stats(struct blkio_group *blkg,
+                bool direction, bool sync)
+{
+        blkiocg_update_io_merged_stats(blkg, direction, sync);
+}
+
+static inline void cfq_blkiocg_update_idle_time_stats(struct blkio_group *blkg)
+{
+        blkiocg_update_idle_time_stats(blkg);
+}
+
+static inline void
+cfq_blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg)
+{
+        blkiocg_update_avg_queue_size_stats(blkg);
+}
+
+static inline void
+cfq_blkiocg_update_set_idle_time_stats(struct blkio_group *blkg)
+{
+        blkiocg_update_set_idle_time_stats(blkg);
+}
+
+static inline void cfq_blkiocg_update_dispatch_stats(struct blkio_group *blkg,
+                                uint64_t bytes, bool direction, bool sync)
+{
+        blkiocg_update_dispatch_stats(blkg, bytes, direction, sync);
+}
+
+static inline void cfq_blkiocg_update_completion_stats(struct blkio_group *blkg, uint64_t start_time, uint64_t io_start_time, bool direction, bool sync)
+{
+        blkiocg_update_completion_stats(blkg, start_time, io_start_time,
+                                direction, sync);
+}
+
+static inline void cfq_blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+                        struct blkio_group *blkg, void *key, dev_t dev) {
+        blkiocg_add_blkio_group(blkcg, blkg, key, dev);
+}
+
+static inline int cfq_blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+        return blkiocg_del_blkio_group(blkg);
+}
+
+#else /* CFQ_GROUP_IOSCHED */
+static inline void cfq_blkiocg_update_io_add_stats(struct blkio_group *blkg,
+        struct blkio_group *curr_blkg, bool direction, bool sync) {}
+
+static inline void cfq_blkiocg_update_dequeue_stats(struct blkio_group *blkg,
+                        unsigned long dequeue) {}
+
+static inline void cfq_blkiocg_update_timeslice_used(struct blkio_group *blkg,
+                        unsigned long time) {}
+static inline void cfq_blkiocg_set_start_empty_time(struct blkio_group *blkg) {}
+static inline void cfq_blkiocg_update_io_remove_stats(struct blkio_group *blkg,
+                                bool direction, bool sync) {}
+static inline void cfq_blkiocg_update_io_merged_stats(struct blkio_group *blkg,
+                bool direction, bool sync) {}
+static inline void cfq_blkiocg_update_idle_time_stats(struct blkio_group *blkg)
+{
+}
+static inline void
+cfq_blkiocg_update_avg_queue_size_stats(struct blkio_group *blkg) {}
+
+static inline void
+cfq_blkiocg_update_set_idle_time_stats(struct blkio_group *blkg) {}
+
+static inline void cfq_blkiocg_update_dispatch_stats(struct blkio_group *blkg,
+                                uint64_t bytes, bool direction, bool sync) {}
+static inline void cfq_blkiocg_update_completion_stats(struct blkio_group *blkg, uint64_t start_time, uint64_t io_start_time, bool direction, bool sync) {}
+
+static inline void cfq_blkiocg_add_blkio_group(struct blkio_cgroup *blkcg,
+                        struct blkio_group *blkg, void *key, dev_t dev) {}
+static inline int cfq_blkiocg_del_blkio_group(struct blkio_group *blkg)
+{
+        return 0;
+}
+
+#endif /* CFQ_GROUP_IOSCHED */
+#endif