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

* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
  block: Range check cpu in blk_cpu_to_group
  scatterlist: prevent invalid free when alloc fails
  writeback: Fix lost wake-up shutting down writeback thread
  writeback: do not lose wakeup events when forking bdi threads
  cciss: fix reporting of max queue depth since init
  block: switch s390 tape_block and mg_disk to elevator_change()
  block: add function call to switch the IO scheduler from a driver
  fs/bio-integrity.c: return -ENOMEM on kmalloc failure
  bio-integrity.c: remove dependency on __GFP_NOFAIL
  BLOCK: fix bio.bi_rw handling
  block: put dev->kobj in blk_register_queue fail path
  cciss: handle allocation failure
  cfq-iosched: Documentation help for new tunables
  cfq-iosched: blktrace print per slice sector stats
  cfq-iosched: Implement tunable group_idle
  cfq-iosched: Do group share accounting in IOPS when slice_idle=0
  cfq-iosched: Do not idle if slice_idle=0
  cciss: disable doorbell reset on reset_devices
  blkio: Fix return code for mkdir calls

17 files changed, 238 insertions, 46 deletions

diff --git a/Documentation/block/cfq-iosched.txt b/Documentation/block/cfq-iosched.txt
new file mode 100644
index 000000000000..e578feed6d81
--- /dev/null
+++ b/Documentation/block/cfq-iosched.txt
@@ -0,0 +1,45 @@
+CFQ ioscheduler tunables
+========================
+
+slice_idle
+----------
+This specifies how long CFQ should idle for next request on certain cfq queues
+(for sequential workloads) and service trees (for random workloads) before
+queue is expired and CFQ selects next queue to dispatch from.
+
+By default slice_idle is a non-zero value. That means by default we idle on
+queues/service trees. This can be very helpful on highly seeky media like
+single spindle SATA/SAS disks where we can cut down on overall number of
+seeks and see improved throughput.
+
+Setting slice_idle to 0 will remove all the idling on queues/service tree
+level and one should see an overall improved throughput on faster storage
+devices like multiple SATA/SAS disks in hardware RAID configuration. The down
+side is that isolation provided from WRITES also goes down and notion of
+IO priority becomes weaker.
+
+So depending on storage and workload, it might be useful to set slice_idle=0.
+In general I think for SATA/SAS disks and software RAID of SATA/SAS disks
+keeping slice_idle enabled should be useful. For any configurations where
+there are multiple spindles behind single LUN (Host based hardware RAID
+controller or for storage arrays), setting slice_idle=0 might end up in better
+throughput and acceptable latencies.
+
+CFQ IOPS Mode for group scheduling
+===================================
+Basic CFQ design is to provide priority based time slices. Higher priority
+process gets bigger time slice and lower priority process gets smaller time
+slice. Measuring time becomes harder if storage is fast and supports NCQ and
+it would be better to dispatch multiple requests from multiple cfq queues in
+request queue at a time. In such scenario, it is not possible to measure time
+consumed by single queue accurately.
+
+What is possible though is to measure number of requests dispatched from a
+single queue and also allow dispatch from multiple cfq queue at the same time.
+This effectively becomes the fairness in terms of IOPS (IO operations per
+second).
+
+If one sets slice_idle=0 and if storage supports NCQ, CFQ internally switches
+to IOPS mode and starts providing fairness in terms of number of requests
+dispatched. Note that this mode switching takes effect only for group
+scheduling. For non-cgroup users nothing should change.
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 48e0b21b0059..6919d62591d9 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -217,6 +217,7 @@ Details of cgroup files
 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
@@ -243,6 +244,33 @@ 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.
+This happens because CFQ idles on a single queue and single queue might not
+drive deeper request queue depths to keep the storage busy. In such scenarios
+one can try setting slice_idle=0 and that would switch CFQ to IOPS
+(IO operations per second) mode on NCQ supporting hardware.
+
+That means CFQ will not idle between cfq queues of a cfq group and hence be
+able to driver higher queue depth and achieve better throughput. That also
+means that cfq provides fairness among groups in terms of IOPS and not in
+terms of disk time.
+
+/sys/block/<disk>/queue/iosched/group_idle
+------------------------------------------
+If one disables idling on individual cfq queues and cfq service trees by
+setting slice_idle=0, group_idle kicks in. That means CFQ will still idle
+on the group in an attempt to provide fairness among groups.
+
+By default group_idle is same as slice_idle and does not do anything if
+slice_idle is enabled.
+
+One can experience an overall throughput drop if you have created multiple
+groups and put applications in that group which are not driving enough
+IO to keep disk busy. In that case set group_idle=0, and CFQ will not idle
+on individual groups and throughput should improve.
+
 What works
 ==========
 - Currently only sync IO queues are support. All the buffered writes are
diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index a6809645d212..2fef1ef931a0 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -966,7 +966,7 @@ blkiocg_create(struct cgroup_subsys *subsys, struct cgroup *cgroup)
 
 	/* Currently we do not support hierarchy deeper than two level (0,1) */
 	if (parent != cgroup->top_cgroup)
-		return ERR_PTR(-EINVAL);
+		return ERR_PTR(-EPERM);
 
 	blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL);
 	if (!blkcg)
diff --git a/block/blk-core.c b/block/blk-core.c
index ee1a1e7e63cc..32a1c123dfb3 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1198,9 +1198,9 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 	int el_ret;
 	unsigned int bytes = bio->bi_size;
 	const unsigned short prio = bio_prio(bio);
-	const bool sync = (bio->bi_rw & REQ_SYNC);
-	const bool unplug = (bio->bi_rw & REQ_UNPLUG);
-	const unsigned int ff = bio->bi_rw & REQ_FAILFAST_MASK;
+	const bool sync = !!(bio->bi_rw & REQ_SYNC);
+	const bool unplug = !!(bio->bi_rw & REQ_UNPLUG);
+	const unsigned long ff = bio->bi_rw & REQ_FAILFAST_MASK;
 	int rw_flags;
 
 	if ((bio->bi_rw & REQ_HARDBARRIER) &&
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 001ab18078f5..0749b89c6885 100644
--- a/block/blk-sysfs.c
+++ b/block/blk-sysfs.c
@@ -511,6 +511,7 @@ int blk_register_queue(struct gendisk *disk)
 		kobject_uevent(&q->kobj, KOBJ_REMOVE);
 		kobject_del(&q->kobj);
 		blk_trace_remove_sysfs(disk_to_dev(disk));
+		kobject_put(&dev->kobj);
 		return ret;
 	}
 
diff --git a/block/blk.h b/block/blk.h
index 6e7dc87141e4..d6b911ac002c 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -142,14 +142,18 @@ static inline int queue_congestion_off_threshold(struct request_queue *q)
 
 static inline int blk_cpu_to_group(int cpu)
 {
+	int group = NR_CPUS;
 #ifdef CONFIG_SCHED_MC
 	const struct cpumask *mask = cpu_coregroup_mask(cpu);
-	return cpumask_first(mask);
+	group = cpumask_first(mask);
 #elif defined(CONFIG_SCHED_SMT)
-	return cpumask_first(topology_thread_cpumask(cpu));
+	group = cpumask_first(topology_thread_cpumask(cpu));
 #else
 	return cpu;
 #endif
+	if (likely(group < NR_CPUS))
+		return group;
+	return cpu;
 }
 
 /*
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index eb4086f7dfef..f65c6f01c475 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -30,6 +30,7 @@ static const int cfq_slice_sync = HZ / 10;
 static int cfq_slice_async = HZ / 25;
 static const int cfq_slice_async_rq = 2;
 static int cfq_slice_idle = HZ / 125;
+static int cfq_group_idle = HZ / 125;
 static const int cfq_target_latency = HZ * 3/10; /* 300 ms */
 static const int cfq_hist_divisor = 4;
 
@@ -147,6 +148,8 @@ struct cfq_queue {
 	struct cfq_queue *new_cfqq;
 	struct cfq_group *cfqg;
 	struct cfq_group *orig_cfqg;
+	/* Number of sectors dispatched from queue in single dispatch round */
+	unsigned long nr_sectors;
 };
 
 /*
@@ -198,6 +201,8 @@ struct cfq_group {
 	struct hlist_node cfqd_node;
 	atomic_t ref;
 #endif
+	/* number of requests that are on the dispatch list or inside driver */
+	int dispatched;
 };
 
 /*
@@ -271,6 +276,7 @@ struct cfq_data {
 	unsigned int cfq_slice[2];
 	unsigned int cfq_slice_async_rq;
 	unsigned int cfq_slice_idle;
+	unsigned int cfq_group_idle;
 	unsigned int cfq_latency;
 	unsigned int cfq_group_isolation;
 
@@ -378,6 +384,21 @@ CFQ_CFQQ_FNS(wait_busy);
 			&cfqg->service_trees[i][j]: NULL) \
 
 
+static inline bool iops_mode(struct cfq_data *cfqd)
+{
+	/*
+	 * If we are not idling on queues and it is a NCQ drive, parallel
+	 * execution of requests is on and measuring time is not possible
+	 * in most of the cases until and unless we drive shallower queue
+	 * depths and that becomes a performance bottleneck. In such cases
+	 * switch to start providing fairness in terms of number of IOs.
+	 */
+	if (!cfqd->cfq_slice_idle && cfqd->hw_tag)
+		return true;
+	else
+		return false;
+}
+
 static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq)
 {
 	if (cfq_class_idle(cfqq))
@@ -906,7 +927,6 @@ static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
 			slice_used = cfqq->allocated_slice;
 	}
 
-	cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u", slice_used);
 	return slice_used;
 }
 
@@ -914,19 +934,21 @@ static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg,
 				struct cfq_queue *cfqq)
 {
 	struct cfq_rb_root *st = &cfqd->grp_service_tree;
-	unsigned int used_sl, charge_sl;
+	unsigned int used_sl, charge;
 	int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg)
 			- cfqg->service_tree_idle.count;
 
 	BUG_ON(nr_sync < 0);
-	used_sl = charge_sl = cfq_cfqq_slice_usage(cfqq);
+	used_sl = charge = cfq_cfqq_slice_usage(cfqq);
 
-	if (!cfq_cfqq_sync(cfqq) && !nr_sync)
-		charge_sl = cfqq->allocated_slice;
+	if (iops_mode(cfqd))
+		charge = cfqq->slice_dispatch;
+	else if (!cfq_cfqq_sync(cfqq) && !nr_sync)
+		charge = cfqq->allocated_slice;
 
 	/* Can't update vdisktime while group is on service tree */
 	cfq_rb_erase(&cfqg->rb_node, st);
-	cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
+	cfqg->vdisktime += cfq_scale_slice(charge, cfqg);
 	__cfq_group_service_tree_add(st, cfqg);
 
 	/* This group is being expired. Save the context */
@@ -940,6 +962,9 @@ 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);
+	cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u disp=%u charge=%u iops=%u"
+			" sect=%u", used_sl, cfqq->slice_dispatch, charge,
+			iops_mode(cfqd), cfqq->nr_sectors);
 	cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl);
 	cfq_blkiocg_set_start_empty_time(&cfqg->blkg);
 }
@@ -1587,6 +1612,7 @@ static void __cfq_set_active_queue(struct cfq_data *cfqd,
 		cfqq->allocated_slice = 0;
 		cfqq->slice_end = 0;
 		cfqq->slice_dispatch = 0;
+		cfqq->nr_sectors = 0;
 
 		cfq_clear_cfqq_wait_request(cfqq);
 		cfq_clear_cfqq_must_dispatch(cfqq);
@@ -1839,6 +1865,9 @@ static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq)
 	BUG_ON(!service_tree);
 	BUG_ON(!service_tree->count);
 
+	if (!cfqd->cfq_slice_idle)
+		return false;
+
 	/* We never do for idle class queues. */
 	if (prio == IDLE_WORKLOAD)
 		return false;
@@ -1863,7 +1892,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 {
 	struct cfq_queue *cfqq = cfqd->active_queue;
 	struct cfq_io_context *cic;
-	unsigned long sl;
+	unsigned long sl, group_idle = 0;
 
 	/*
 	 * SSD device without seek penalty, disable idling. But only do so
@@ -1879,8 +1908,13 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 	/*
 	 * idle is disabled, either manually or by past process history
 	 */
-	if (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
-		return;
+	if (!cfq_should_idle(cfqd, cfqq)) {
+		/* no queue idling. Check for group idling */
+		if (cfqd->cfq_group_idle)
+			group_idle = cfqd->cfq_group_idle;
+		else
+			return;
+	}
 
 	/*
 	 * still active requests from this queue, don't idle
@@ -1907,13 +1941,21 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
 		return;
 	}
 
+	/* There are other queues in the group, don't do group idle */
+	if (group_idle && cfqq->cfqg->nr_cfqq > 1)
+		return;
+
 	cfq_mark_cfqq_wait_request(cfqq);
 
-	sl = cfqd->cfq_slice_idle;
+	if (group_idle)
+		sl = cfqd->cfq_group_idle;
+	else
+		sl = cfqd->cfq_slice_idle;
 
 	mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
 	cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg);
-	cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
+	cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl,
+			group_idle ? 1 : 0);
 }
 
 /*
@@ -1929,9 +1971,11 @@ static void cfq_dispatch_insert(struct request_queue *q, struct request *rq)
 	cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq);
 	cfq_remove_request(rq);
 	cfqq->dispatched++;
+	(RQ_CFQG(rq))->dispatched++;
 	elv_dispatch_sort(q, rq);
 
 	cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++;
+	cfqq->nr_sectors += blk_rq_sectors(rq);
 	cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq),
 					rq_data_dir(rq), rq_is_sync(rq));
 }
@@ -2198,7 +2242,7 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 			cfqq = NULL;
 			goto keep_queue;
 		} else
-			goto expire;
+			goto check_group_idle;
 	}
 
 	/*
@@ -2226,8 +2270,23 @@ static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd)
 	 * flight or is idling for a new request, allow either of these
 	 * conditions to happen (or time out) before selecting a new queue.
 	 */
-	if (timer_pending(&cfqd->idle_slice_timer) ||
-	    (cfqq->dispatched && cfq_should_idle(cfqd, cfqq))) {
+	if (timer_pending(&cfqd->idle_slice_timer)) {
+		cfqq = NULL;
+		goto keep_queue;
+	}
+
+	if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) {
+		cfqq = NULL;
+		goto keep_queue;
+	}
+
+	/*
+	 * If group idle is enabled and there are requests dispatched from
+	 * this group, wait for requests to complete.
+	 */
+check_group_idle:
+	if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1
+	    && cfqq->cfqg->dispatched) {
 		cfqq = NULL;
 		goto keep_queue;
 	}
@@ -3375,6 +3434,7 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
 	WARN_ON(!cfqq->dispatched);
 	cfqd->rq_in_driver--;
 	cfqq->dispatched--;
+	(RQ_CFQG(rq))->dispatched--;
 	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));
@@ -3404,7 +3464,10 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
 		 * the queue.
 		 */
 		if (cfq_should_wait_busy(cfqd, cfqq)) {
-			cfqq->slice_end = jiffies + cfqd->cfq_slice_idle;
+			unsigned long extend_sl = cfqd->cfq_slice_idle;
+			if (!cfqd->cfq_slice_idle)
+				extend_sl = cfqd->cfq_group_idle;
+			cfqq->slice_end = jiffies + extend_sl;
 			cfq_mark_cfqq_wait_busy(cfqq);
 			cfq_log_cfqq(cfqd, cfqq, "will busy wait");
 		}
@@ -3850,6 +3913,7 @@ static void *cfq_init_queue(struct request_queue *q)
 	cfqd->cfq_slice[1] = cfq_slice_sync;
 	cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
 	cfqd->cfq_slice_idle = cfq_slice_idle;
+	cfqd->cfq_group_idle = cfq_group_idle;
 	cfqd->cfq_latency = 1;
 	cfqd->cfq_group_isolation = 0;
 	cfqd->hw_tag = -1;
@@ -3922,6 +3986,7 @@ SHOW_FUNCTION(cfq_fifo_expire_async_show, cfqd->cfq_fifo_expire[0], 1);
 SHOW_FUNCTION(cfq_back_seek_max_show, cfqd->cfq_back_max, 0);
 SHOW_FUNCTION(cfq_back_seek_penalty_show, cfqd->cfq_back_penalty, 0);
 SHOW_FUNCTION(cfq_slice_idle_show, cfqd->cfq_slice_idle, 1);
+SHOW_FUNCTION(cfq_group_idle_show, cfqd->cfq_group_idle, 1);
 SHOW_FUNCTION(cfq_slice_sync_show, cfqd->cfq_slice[1], 1);
 SHOW_FUNCTION(cfq_slice_async_show, cfqd->cfq_slice[0], 1);
 SHOW_FUNCTION(cfq_slice_async_rq_show, cfqd->cfq_slice_async_rq, 0);
@@ -3954,6 +4019,7 @@ STORE_FUNCTION(cfq_back_seek_max_store, &cfqd->cfq_back_max, 0, UINT_MAX, 0);
 STORE_FUNCTION(cfq_back_seek_penalty_store, &cfqd->cfq_back_penalty, 1,
 		UINT_MAX, 0);
 STORE_FUNCTION(cfq_slice_idle_store, &cfqd->cfq_slice_idle, 0, UINT_MAX, 1);
+STORE_FUNCTION(cfq_group_idle_store, &cfqd->cfq_group_idle, 0, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_sync_store, &cfqd->cfq_slice[1], 1, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_async_store, &cfqd->cfq_slice[0], 1, UINT_MAX, 1);
 STORE_FUNCTION(cfq_slice_async_rq_store, &cfqd->cfq_slice_async_rq, 1,
@@ -3975,6 +4041,7 @@ static struct elv_fs_entry cfq_attrs[] = {
 	CFQ_ATTR(slice_async),
 	CFQ_ATTR(slice_async_rq),
 	CFQ_ATTR(slice_idle),
+	CFQ_ATTR(group_idle),
 	CFQ_ATTR(low_latency),
 	CFQ_ATTR(group_isolation),
 	__ATTR_NULL
@@ -4028,6 +4095,12 @@ static int __init cfq_init(void)
 	if (!cfq_slice_idle)
 		cfq_slice_idle = 1;
 
+#ifdef CONFIG_CFQ_GROUP_IOSCHED
+	if (!cfq_group_idle)
+		cfq_group_idle = 1;
+#else
+		cfq_group_idle = 0;
+#endif
 	if (cfq_slab_setup())
 		return -ENOMEM;
 
diff --git a/block/elevator.c b/block/elevator.c
index ec585c9554d3..205b09a5bd9e 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -1009,18 +1009,19 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 {
 	struct elevator_queue *old_elevator, *e;
 	void *data;
+	int err;
 
 	/*
 	 * Allocate new elevator
 	 */
 	e = elevator_alloc(q, new_e);
 	if (!e)
-		return 0;
+		return -ENOMEM;
 
 	data = elevator_init_queue(q, e);
 	if (!data) {
 		kobject_put(&e->kobj);
-		return 0;
+		return -ENOMEM;
 	}
 
 	/*
@@ -1043,7 +1044,8 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 	__elv_unregister_queue(old_elevator);
 
-	if (elv_register_queue(q))
+	err = elv_register_queue(q);
+	if (err)
 		goto fail_register;
 
 	/*
@@ -1056,7 +1058,7 @@ static int elevator_switch(struct request_queue *q, struct elevator_type *new_e)
 
 	blk_add_trace_msg(q, "elv switch: %s", e->elevator_type->elevator_name);
 
-	return 1;
+	return 0;
 
 fail_register:
 	/*
@@ -1071,17 +1073,19 @@ fail_register:
 	queue_flag_clear(QUEUE_FLAG_ELVSWITCH, q);
 	spin_unlock_irq(q->queue_lock);
 
-	return 0;
+	return err;
 }
 
-ssize_t elv_iosched_store(struct request_queue *q, const char *name,
-			  size_t count)
+/*
+ * Switch this queue to the given IO scheduler.
+ */
+int elevator_change(struct request_queue *q, const char *name)
 {
 	char elevator_name[ELV_NAME_MAX];
 	struct elevator_type *e;
 
 	if (!q->elevator)
-		return count;
+		return -ENXIO;
 
 	strlcpy(elevator_name, name, sizeof(elevator_name));
 	e = elevator_get(strstrip(elevator_name));
@@ -1092,13 +1096,27 @@ ssize_t elv_iosched_store(struct request_queue *q, const char *name,
 
 	if (!strcmp(elevator_name, q->elevator->elevator_type->elevator_name)) {
 		elevator_put(e);
-		return count;
+		return 0;
 	}
 
-	if (!elevator_switch(q, e))
-		printk(KERN_ERR "elevator: switch to %s failed\n",
-							elevator_name);
-	return count;
+	return elevator_switch(q, e);
+}
+EXPORT_SYMBOL(elevator_change);
+
+ssize_t elv_iosched_store(struct request_queue *q, const char *name,
+			  size_t count)
+{
+	int ret;
+
+	if (!q->elevator)
+		return count;
+
+	ret = elevator_change(q, name);
+	if (!ret)
+		return count;
+
+	printk(KERN_ERR "elevator: switch to %s failed\n", name);
+	return ret;
 }
 
 ssize_t elv_iosched_show(struct request_queue *q, char *name)
diff --git a/drivers/block/cciss.c b/drivers/block/cciss.c
index 31064df1370a..6124c2fd2d33 100644
--- a/drivers/block/cciss.c
+++ b/drivers/block/cciss.c
@@ -297,6 +297,8 @@ static void enqueue_cmd_and_start_io(ctlr_info_t *h,
 	spin_lock_irqsave(&h->lock, flags);
 	addQ(&h->reqQ, c);
 	h->Qdepth++;
+	if (h->Qdepth > h->maxQsinceinit)
+		h->maxQsinceinit = h->Qdepth;
 	start_io(h);
 	spin_unlock_irqrestore(&h->lock, flags);
 }
@@ -4519,6 +4521,12 @@ static __devinit int cciss_kdump_hard_reset_controller(struct pci_dev *pdev)
 	misc_fw_support = readl(&cfgtable->misc_fw_support);
 	use_doorbell = misc_fw_support & MISC_FW_DOORBELL_RESET;
 
+	/* The doorbell reset seems to cause lockups on some Smart
+	 * Arrays (e.g. P410, P410i, maybe others).  Until this is
+	 * fixed or at least isolated, avoid the doorbell reset.
+	 */
+	use_doorbell = 0;
+
 	rc = cciss_controller_hard_reset(pdev, vaddr, use_doorbell);
 	if (rc)
 		goto unmap_cfgtable;
@@ -4712,6 +4720,9 @@ static int __devinit cciss_init_one(struct pci_dev *pdev,
 	h->scatter_list = kmalloc(h->max_commands *
 						sizeof(struct scatterlist *),
 						GFP_KERNEL);
+	if (!h->scatter_list)
+		goto clean4;
+
 	for (k = 0; k < h->nr_cmds; k++) {
 		h->scatter_list[k] = kmalloc(sizeof(struct scatterlist) *
 							h->maxsgentries,
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index f3c636d23718..91797bbbe702 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -477,7 +477,7 @@ static int do_bio_filebacked(struct loop_device *lo, struct bio *bio)
 	pos = ((loff_t) bio->bi_sector << 9) + lo->lo_offset;
 
 	if (bio_rw(bio) == WRITE) {
-		bool barrier = (bio->bi_rw & REQ_HARDBARRIER);
+		bool barrier = !!(bio->bi_rw & REQ_HARDBARRIER);
 		struct file *file = lo->lo_backing_file;
 
 		if (barrier) {
diff --git a/drivers/block/mg_disk.c b/drivers/block/mg_disk.c
index b82c5ce5e9df..76fa3deaee84 100644
--- a/drivers/block/mg_disk.c
+++ b/drivers/block/mg_disk.c
@@ -974,8 +974,7 @@ static int mg_probe(struct platform_device *plat_dev)
 	host->breq->queuedata = host;
 
 	/* mflash is random device, thanx for the noop */
-	elevator_exit(host->breq->elevator);
-	err = elevator_init(host->breq, "noop");
+	err = elevator_change(host->breq, "noop");
 	if (err) {
 		printk(KERN_ERR "%s:%d (elevator_init) fail\n",
 				__func__, __LINE__);
diff --git a/drivers/s390/char/tape_block.c b/drivers/s390/char/tape_block.c
index b7de02525ec9..85cf607fc78f 100644
--- a/drivers/s390/char/tape_block.c
+++ b/drivers/s390/char/tape_block.c
@@ -217,8 +217,7 @@ tapeblock_setup_device(struct tape_device * device)
 	if (!blkdat->request_queue)
 		return -ENOMEM;
 
-	elevator_exit(blkdat->request_queue->elevator);
-	rc = elevator_init(blkdat->request_queue, "noop");
+	rc = elevator_change(blkdat->request_queue, "noop");
 	if (rc)
 		goto cleanup_queue;
 
diff --git a/fs/bio-integrity.c b/fs/bio-integrity.c
index 612a5c38d3c1..4d0ff5ee27b8 100644
--- a/fs/bio-integrity.c
+++ b/fs/bio-integrity.c
@@ -413,10 +413,10 @@ int bio_integrity_prep(struct bio *bio)
 
 	/* Allocate kernel buffer for protection data */
 	len = sectors * blk_integrity_tuple_size(bi);
-	buf = kmalloc(len, GFP_NOIO | __GFP_NOFAIL | q->bounce_gfp);
+	buf = kmalloc(len, GFP_NOIO | q->bounce_gfp);
 	if (unlikely(buf == NULL)) {
 		printk(KERN_ERR "could not allocate integrity buffer\n");
-		return -EIO;
+		return -ENOMEM;
 	}
 
 	end = (((unsigned long) buf) + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 7d9d06ba184b..81e086d8aa57 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -808,7 +808,7 @@ int bdi_writeback_thread(void *data)
 			wb->last_active = jiffies;
 
 		set_current_state(TASK_INTERRUPTIBLE);
-		if (!list_empty(&bdi->work_list)) {
+		if (!list_empty(&bdi->work_list) || kthread_should_stop()) {
 			__set_current_state(TASK_RUNNING);
 			continue;
 		}
diff --git a/include/linux/elevator.h b/include/linux/elevator.h
index 2c958f4fce1e..926b50322a46 100644
--- a/include/linux/elevator.h
+++ b/include/linux/elevator.h
@@ -136,6 +136,7 @@ extern ssize_t elv_iosched_store(struct request_queue *, const char *, size_t);
 
 extern int elevator_init(struct request_queue *, char *);
 extern void elevator_exit(struct elevator_queue *);
+extern int elevator_change(struct request_queue *, const char *);
 extern int elv_rq_merge_ok(struct request *, struct bio *);
 
 /*
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index a5ec42868f99..4ceb05d772ae 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -248,8 +248,18 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
 		left -= sg_size;
 
 		sg = alloc_fn(alloc_size, gfp_mask);
-		if (unlikely(!sg))
-			return -ENOMEM;
+		if (unlikely(!sg)) {
+			/*
+			 * Adjust entry count to reflect that the last
+			 * entry of the previous table won't be used for
+			 * linkage.  Without this, sg_kfree() may get
+			 * confused.
+			 */
+			if (prv)
+				table->nents = ++table->orig_nents;
+
+ 			return -ENOMEM;
+		}
 
 		sg_init_table(sg, alloc_size);
 		table->nents = table->orig_nents += sg_size;
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index eaa4a5bbe063..c2bf86f470ed 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -445,8 +445,8 @@ static int bdi_forker_thread(void *ptr)
 		switch (action) {
 		case FORK_THREAD:
 			__set_current_state(TASK_RUNNING);
-			task = kthread_run(bdi_writeback_thread, &bdi->wb, "flush-%s",
-					   dev_name(bdi->dev));
+			task = kthread_create(bdi_writeback_thread, &bdi->wb,
+					      "flush-%s", dev_name(bdi->dev));
 			if (IS_ERR(task)) {
 				/*
 				 * If thread creation fails, force writeout of
@@ -457,10 +457,13 @@ static int bdi_forker_thread(void *ptr)
 				/*
 				 * The spinlock makes sure we do not lose
 				 * wake-ups when racing with 'bdi_queue_work()'.
+				 * And as soon as the bdi thread is visible, we
+				 * can start it.
 				 */
 				spin_lock_bh(&bdi->wb_lock);
 				bdi->wb.task = task;
 				spin_unlock_bh(&bdi->wb_lock);
+				wake_up_process(task);
 			}
 			break;