Merge branch 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block

* 'for-2.6.39/core' of git://git.kernel.dk/linux-2.6-block: (65 commits)
  Documentation/iostats.txt: bit-size reference etc.
  cfq-iosched: removing unnecessary think time checking
  cfq-iosched: Don't clear queue stats when preempt.
  blk-throttle: Reset group slice when limits are changed
  blk-cgroup: Only give unaccounted_time under debug
  cfq-iosched: Don't set active queue in preempt
  block: fix non-atomic access to genhd inflight structures
  block: attempt to merge with existing requests on plug flush
  block: NULL dereference on error path in __blkdev_get()
  cfq-iosched: Don't update group weights when on service tree
  fs: assign sb->s_bdi to default_backing_dev_info if the bdi is going away
  block: Require subsystems to explicitly allocate bio_set integrity mempool
  jbd2: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  jbd: finish conversion from WRITE_SYNC_PLUG to WRITE_SYNC and explicit plugging
  fs: make fsync_buffers_list() plug
  mm: make generic_writepages() use plugging
  blk-cgroup: Add unaccounted time to timeslice_used.
  block: fixup plugging stubs for !CONFIG_BLOCK
  block: remove obsolete comments for blkdev_issue_zeroout.
  blktrace: Use rq->cmd_flags directly in blk_add_trace_rq.
  ...

Fix up conflicts in fs/{aio.c,super.c}

Author: torvalds

Documentation/block/biodoc.txt

@@ -963,11 +963,6 @@ elevator_dispatch_fn*		fills the dispatch queue with ready requests.
 
 elevator_add_req_fn*		called to add a new request into the scheduler
 
-elevator_queue_empty_fn		returns true if the merge queue is empty.
-				Drivers shouldn't use this, but rather check
-				if elv_next_request is NULL (without losing the
-				request if one exists!)
-
 elevator_former_req_fn
 elevator_latter_req_fn		These return the request before or after the
 				one specified in disk sort order. Used by the

Documentation/cgroups/blkio-controller.txt

@@ -140,7 +140,7 @@ Proportional weight policy files
 	- Specifies per cgroup weight. This is default weight of the group
 	  on all the devices until and unless overridden by per device rule.
 	  (See blkio.weight_device).
-	  Currently allowed range of weights is from 100 to 1000.
+	  Currently allowed range of weights is from 10 to 1000.
 
 - blkio.weight_device
 	- One can specify per cgroup per device rules using this interface.
@@ -343,34 +343,6 @@ Common files among various policies
 
 CFQ sysfs tunable
 =================
-/sys/block/<disk>/queue/iosched/group_isolation
------------------------------------------------
-
-If group_isolation=1, it provides stronger isolation between groups at the
-expense of throughput. By default group_isolation is 0. In general that
-means that if group_isolation=0, expect fairness for sequential workload
-only. Set group_isolation=1 to see fairness for random IO workload also.
-
-Generally CFQ will put random seeky workload in sync-noidle category. CFQ
-will disable idling on these queues and it does a collective idling on group
-of such queues. Generally these are slow moving queues and if there is a
-sync-noidle service tree in each group, that group gets exclusive access to
-disk for certain period. That means it will bring the throughput down if
-group does not have enough IO to drive deeper queue depths and utilize disk
-capacity to the fullest in the slice allocated to it. But the flip side is
-that even a random reader should get better latencies and overall throughput
-if there are lots of sequential readers/sync-idle workload running in the
-system.
-
-If group_isolation=0, then CFQ automatically moves all the random seeky queues
-in the root group. That means there will be no service differentiation for
-that kind of workload. This leads to better throughput as we do collective
-idling on root sync-noidle tree.
-
-By default one should run with group_isolation=0. If that is not sufficient
-and one wants stronger isolation between groups, then set group_isolation=1
-but this will come at cost of reduced throughput.
-
 /sys/block/<disk>/queue/iosched/slice_idle
 ------------------------------------------
 On a faster hardware CFQ can be slow, especially with sequential workload.

Documentation/iostats.txt

@@ -1,8 +1,6 @@
 I/O statistics fields
 ---------------
 
-Last modified Sep 30, 2003
-
 Since 2.4.20 (and some versions before, with patches), and 2.5.45,
 more extensive disk statistics have been introduced to help measure disk
 activity. Tools such as sar and iostat typically interpret these and do
@@ -46,11 +44,12 @@ the above example, the first field of statistics would be 446216.
 By contrast, in 2.6 if you look at /sys/block/hda/stat, you'll
 find just the eleven fields, beginning with 446216.  If you look at
 /proc/diskstats, the eleven fields will be preceded by the major and
-minor device numbers, and device name.  Each of these formats provide
+minor device numbers, and device name.  Each of these formats provides
 eleven fields of statistics, each meaning exactly the same things.
 All fields except field 9 are cumulative since boot.  Field 9 should
-go to zero as I/Os complete; all others only increase.  Yes, these are
-32 bit unsigned numbers, and on a very busy or long-lived system they
+go to zero as I/Os complete; all others only increase (unless they
+overflow and wrap).  Yes, these are (32-bit or 64-bit) unsigned long
+(native word size) numbers, and on a very busy or long-lived system they
 may wrap. Applications should be prepared to deal with that; unless
 your observations are measured in large numbers of minutes or hours,
 they should not wrap twice before you notice them.
@@ -96,11 +95,11 @@ introduced when changes collide, so (for instance) adding up all the
 read I/Os issued per partition should equal those made to the disks ...
 but due to the lack of locking it may only be very close.
 
-In 2.6, there are counters for each cpu, which made the lack of locking
-almost a non-issue.  When the statistics are read, the per-cpu counters
-are summed (possibly overflowing the unsigned 32-bit variable they are
+In 2.6, there are counters for each CPU, which make the lack of locking
+almost a non-issue.  When the statistics are read, the per-CPU counters
+are summed (possibly overflowing the unsigned long variable they are
 summed to) and the result given to the user.  There is no convenient
-user interface for accessing the per-cpu counters themselves.
+user interface for accessing the per-CPU counters themselves.
 
 Disks vs Partitions
 -------------------

block/blk-cgroup.c

@@ -371,12 +371,14 @@ void blkiocg_update_io_remove_stats(struct blkio_group *blkg,
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_io_remove_stats);
 
-void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time)
+void blkiocg_update_timeslice_used(struct blkio_group *blkg, unsigned long time,
+				unsigned long unaccounted_time)
 {
 	unsigned long flags;
 
 	spin_lock_irqsave(&blkg->stats_lock, flags);
 	blkg->stats.time += time;
+	blkg->stats.unaccounted_time += unaccounted_time;
 	spin_unlock_irqrestore(&blkg->stats_lock, flags);
 }
 EXPORT_SYMBOL_GPL(blkiocg_update_timeslice_used);
@@ -604,6 +606,9 @@ static uint64_t blkio_get_stat(struct blkio_group *blkg,
 		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
 					blkg->stats.sectors, cb, dev);
 #ifdef CONFIG_DEBUG_BLK_CGROUP
+	if (type == BLKIO_STAT_UNACCOUNTED_TIME)
+		return blkio_fill_stat(key_str, MAX_KEY_LEN - 1,
+					blkg->stats.unaccounted_time, cb, dev);
 	if (type == BLKIO_STAT_AVG_QUEUE_SIZE) {
 		uint64_t sum = blkg->stats.avg_queue_size_sum;
 		uint64_t samples = blkg->stats.avg_queue_size_samples;
@@ -1125,6 +1130,9 @@ static int blkiocg_file_read_map(struct cgroup *cgrp, struct cftype *cft,
 			return blkio_read_blkg_stats(blkcg, cft, cb,
 						BLKIO_STAT_QUEUED, 1);
 #ifdef CONFIG_DEBUG_BLK_CGROUP
+		case BLKIO_PROP_unaccounted_time:
+			return blkio_read_blkg_stats(blkcg, cft, cb,
+						BLKIO_STAT_UNACCOUNTED_TIME, 0);
 		case BLKIO_PROP_dequeue:
 			return blkio_read_blkg_stats(blkcg, cft, cb,
 						BLKIO_STAT_DEQUEUE, 0);
@@ -1382,6 +1390,12 @@ struct cftype blkio_files[] = {
 				BLKIO_PROP_dequeue),
 		.read_map = blkiocg_file_read_map,
 	},
+	{
+		.name = "unaccounted_time",
+		.private = BLKIOFILE_PRIVATE(BLKIO_POLICY_PROP,
+				BLKIO_PROP_unaccounted_time),
+		.read_map = blkiocg_file_read_map,
+	},
 #endif
 };
 

block/blk-cgroup.h

@@ -49,6 +49,8 @@ enum stat_type {
 	/* All the single valued stats go below this */
 	BLKIO_STAT_TIME,
 	BLKIO_STAT_SECTORS,
+	/* Time not charged to this cgroup */
+	BLKIO_STAT_UNACCOUNTED_TIME,
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	BLKIO_STAT_AVG_QUEUE_SIZE,
 	BLKIO_STAT_IDLE_TIME,
@@ -81,6 +83,7 @@ enum blkcg_file_name_prop {
 	BLKIO_PROP_io_serviced,
 	BLKIO_PROP_time,
 	BLKIO_PROP_sectors,
+	BLKIO_PROP_unaccounted_time,
 	BLKIO_PROP_io_service_time,
 	BLKIO_PROP_io_wait_time,
 	BLKIO_PROP_io_merged,
@@ -114,6 +117,8 @@ struct blkio_group_stats {
 	/* total disk time and nr sectors dispatched by this group */
 	uint64_t time;
 	uint64_t sectors;
+	/* Time not charged to this cgroup */
+	uint64_t unaccounted_time;
 	uint64_t stat_arr[BLKIO_STAT_QUEUED + 1][BLKIO_STAT_TOTAL];
 #ifdef CONFIG_DEBUG_BLK_CGROUP
 	/* Sum of number of IOs queued across all samples */
@@ -240,7 +245,7 @@ static inline char *blkg_path(struct blkio_group *blkg) { return NULL; }
 
 #endif
 
-#define BLKIO_WEIGHT_MIN	100
+#define BLKIO_WEIGHT_MIN	10
 #define BLKIO_WEIGHT_MAX	1000
 #define BLKIO_WEIGHT_DEFAULT	500
 
@@ -293,7 +298,8 @@ extern int blkiocg_del_blkio_group(struct blkio_group *blkg);
 extern struct blkio_group *blkiocg_lookup_group(struct blkio_cgroup *blkcg,
 						void *key);
 void blkiocg_update_timeslice_used(struct blkio_group *blkg,
-					unsigned long time);
+					unsigned long time,
+					unsigned long unaccounted_time);
 void blkiocg_update_dispatch_stats(struct blkio_group *blkg, uint64_t bytes,
 						bool direction, bool sync);
 void blkiocg_update_completion_stats(struct blkio_group *blkg,
@@ -319,7 +325,9 @@ blkiocg_del_blkio_group(struct blkio_group *blkg) { return 0; }
 static inline struct blkio_group *
 blkiocg_lookup_group(struct blkio_cgroup *blkcg, void *key) { return NULL; }
 static inline void blkiocg_update_timeslice_used(struct blkio_group *blkg,
-						unsigned long time) {}
+						unsigned long time,
+						unsigned long unaccounted_time)
+{}
 static inline void blkiocg_update_dispatch_stats(struct blkio_group *blkg,
 				uint64_t bytes, bool direction, bool sync) {}
 static inline void blkiocg_update_completion_stats(struct blkio_group *blkg,